High-yield review for quiz #6, CVS system

Published on June 12, 2018

Lectures:

Congenital heart disease (Embryology and Pathology)

Epidemiology of CVS diseases (Screening schedule, statistics of CVS diseases, modifiable risk factors with a focus on atherosclerosis and dyslipidemias {biochemistry and pharmacology} )

Patent Ductus Arteriosus

A 6-week-old female is brought to the pediatrician because of poor feeding and lack of weight gain. While feeding, she is noted to be diaphoretic and tires easily. On PE, she is tachypneic and quickly loses interest in feeding. It is clear that feeding elicits increased work of breathing. On cardiac auscultation, she has a grade IV continuous murmur heard in the left infraclavicular area. Her pulses are bounding and her liver edge is 3 cm below the costal margin. Her chest X-ray shows an enlarged heart with a prominent main pulmonary artery and increased pulmonary markings.

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Talking Points

  • Describe the role of the ductus arteriosus in the fetal circulation

The ductus arteriosus is a vascular connection that links the arch of the aorta and the pulmonary tract.

In order to understand the purpose of the ductus arteriosus, you must have an understanding of fetal circulation. The placenta acts as the source of oxygen, nutrients, and waste disposal for the fetus. The single umbilical vein arises from the placenta and runs in the umbilical cord. It joins the inferior vena cava, via ductus venosus. Hence, the blood going to the fetus is able to bypass the liver. The inferior vena cava then empties into the right atrium. In fetal life the lungs are not functional yet. This makes logical sense, as the fetus is surrounded by amniotic fluid, and not air, which humans require for effective gas exchange.

The blood flows from the pulmonary artery to the aortic arch via the ductus arteriosus. This blood then supplies the body with oxygen and nutrients. The two umbilical arteries (branches of the internal iliac arteries in fetal life), then flow into the umbilical cord, to the placenta. Here the waste and carbon dioxide is removed by the placenta.

The fetal heart is very different from the adult heart. In order for the blood entering the right atrium to bypass the lungs, there is a large atrial septal defect. Blood is then able to shunt into the left atrium. During fetal life, there are different atrial septal defects at varying times.

Initially there is a single interatrial septum (the septum primum) which forms during the fourth week of gestation. At this point there is a small opening in the septum called the ostium primum. The septum primum grows and causes the ostium primum to narrow and it is obliterated. There is also a widely believed theory that the ostium secundum results from predetermined apoptosis. The ostium secundum is able to provide communication between the atria after the septum primum closes off. After the septum primum has closed, the septum secundum, a second wall of tissue grows to cover the ostium secundum (in the right atrium). At this point the blood is able to flow from the right atrium to the left by way of a small opening in the septum secundum, and through the ostium secundum. Both openings together constitute the foramen ovale.

  • Describe the defects in the wall of the PDA in a term infant and the wall in a premature infant

Before a baby is born, the fetus’s blood does not need to go to the lungs to get oxygenated. The ductus arteriosus is a hole that allows the blood to skip the circulation to the lungs. However, when the baby is born, the blood must receive oxygen in the lungs and this hole is supposed to close. If the ductus arteriosus is still open (or patent) the blood may skip this necessary step of circulation. The open hole is called the patent ductus arteriosus.

Patent ductus arteriosus
Patent ductus arteriosus.svg
Heart cross-section with PDA
Specialty Cardiac surgery

Patent ductus arteriosus (PDA) is a condition wherein the ductus arteriosus fails to close after birth.

Early symptoms are uncommon, but in the first year of life include increased ‘work of breathing’ and poor weight gain. An uncorrected PDA may lead to congestive heart failure with increasing age.

The ductus arteriosus is a fetal blood vessel that closes soon after birth. In a PDA, the vessel does not close and remains “patent” (open), resulting in irregular transmission of blood between the aorta and the pulmonary artery. PDA is common in newborns with persistent respiratory problems such as hypoxia, and has a high occurrence in premature newborns. Premature newborns are more likely to be hypoxic and have PDA due to underdevelopment of the heart and lungs.

A PDA allows a portion of the oxygenated blood from the left heart to flow back to the lungs by flowing from the aorta (which has higher pressure) to the pulmonary artery. If this shunt is substantial, the neonate becomes short of breath: the additional fluid returning to the lungs increases lung pressure, which in turn increases the energy required to inflate the lungs. This uses more calories than normal and often interferes with feeding in infancy. This condition, as a constellation of findings, is called congestive heart failure.

In some congenital heart defects (such as in transposition of the great vessels) a PDA may need to remain open, as it is the only way that oxygenated blood can mix with deoxygenated blood. In these cases, prostaglandins are used to keep the DA open until surgical correction of the heart defect is completed.

 

  • Discuss the situation in which a PDA persists beyond the first week of life in a term infant

(3rd paragraph)

 

Why is PDA a concern?

When the ductus arteriosus stays open, oxygen-rich (red) blood passes from the aorta to the pulmonary artery, mixing with the oxygen-poor (blue) blood already flowing to the lungs. The blood vessels in the lungs have to handle a larger amount of blood than normal. How well the lung vessels are able to adapt to the extra blood flow depends on how big the PDA is and how much blood is able to pass through it from the aorta.

Extra blood causes higher pressure in the blood vessels in the lungs. The larger the volume of blood that goes to the lungs at high pressure, the more the lungs have to cope with this extra blood at high pressure.

Children may have difficulty breathing because of this extra blood flow to the lungs at high pressure. They may remain on the ventilator for a longer period of time if they are premature. The support from the ventilator also may be high, due to this extra blood flow to the lungs.

Rarely, untreated PDA may lead to long-term lung damage. This is uncommon, however, since most children will have been treated for their PDA before the lungs get damaged.

Often, the PDA may be “silent,” that is, causing no symptoms. This is especially true in older patients (beyond the first few months of life) with small PDAs.

  • Compare the chance of spontaneous closure in a premature infant

The likelihood of PDA spontaneous closure in VLBW infants is extremely high.

Although spontaneous ductal closure occurs eventually in nearly a third of extremely premature neonates, more than 60% of all preterm infants born prior to 28 weeks’ gestation receive medical or surgical treatment to prevent complications associated with persistent PDA such as exacerbation of respiratory distress syndrome (RDS) [], pulmonary hemorrhage [], prolonged use of assisted ventilation [], bronchopulmonary dysplasia (BPD) [], intraventricular hemorrhage (IVH)[], renal dysfunction [], necrotizing enterocolitis (NEC) [], periventricular leukomalacia (PVL) [], cerebral palsy [], and mortality [].

Because the ductus does undergo spontaneous closure in some premature infants, improved and early identification of infants most likely to develop a symptomatic PDA could help in directing treatment to the at-risk infants and allow others to receive expectant management.

Whereas this ductal shunt closes spontaneously within a few hours of birth in full-term infants, this process is frequently delayed/ interrupted in premature infants and is associated with increased risk of clinical complications []. I

What are the risk factors for a patent ductus arteriosus?

Persistent patency of the DA is more common among infants born at early gestational age (particularly <28 weeks gestation) and with extremely low birth weight (<1000 grams) who have respiratory disease, particularly those who require mechanical ventilation.

What causes the ductus arteriosus to remain patent?

Closure of the DA occurs in two steps. Initially, the DA constricts in response to increased arterial PaO2 and decreased circulating prostaglandins (particularly E2) following birth. Thereafter, hypoxia from ischemia develops in the wall of the DA. The DA then undergoes transformation into a fibrotic ligamentous structure under the influence of a variety of growth factors.

  • Describe the postnatal pathophysiology of a large PDA

? Above?

  • What is the course of blood flow in a large PDA?

What happens when the ductus arteriosus stays open?

When the ductus arteriosus stays open, blood goes in the opposite direction than it does in the fetus: from the aorta to the lungs. This extra blood, along with the normal flow of blood from the heart to the lungs, can cause a build-up of blood in the baby’s lungs. If the PDA is large, this extra blood flow is too much for the baby to handle and makes it harder for him or her to breathe. Because PDA increases the amount of work for the heart, the baby can have heart failure.

In many cases, the PDA is not large enough to cause symptoms of heart failure in infancy. However, if there is enough blood flow to cause a heart murmur (an abnormal noise), the PDA should be closed. A heart murmur can be heard with a stethoscope when the baby has a PDA.

In some cases, symptoms can occur later in life because of the increased blood flow into the lungs over many years. These symptoms include heart rhythm abnormalities, pulmonary hypertension (high blood pressure in the lung’s blood vessels), and heart failure. Another important reason to close a PDA in children is to prevent bacterial endocarditis, an infection of the blood vessels surrounding the PDA.

  • Describe the clinical manifestations of a large PDA

Patients can present at any age. The typical child with a patent ductus arteriosus (PDA) is asymptomatic. At times, the patient may report decreased exercise tolerance or pulmonary congestion in conjunction with a murmur.

Three-week to 6-week-old infants can present with tachypnea, diaphoresis, inability or difficulty with feeding, and weight loss or no weight gain.

A ductus arteriosus with a moderate-to-large left-to-right shunt may be associated with a hoarse cry, cough, lower respiratory tract infections, atelectasis, or pneumonia. With large defects, the patient may have a history of feeding difficulties and poor growth during infancy, described as failure to thrive (FTT). However, frank symptoms of congestive heart failure (CHF) are rare.

Adults whose patent ductus arteriosus (PDA) has gone undiagnosed may present with signs and symptoms of heart failure, atrial arrhythmia, or even differential cyanosis limited to the lower extremities, indicating shunting of unoxygenated blood from the pulmonary to systemic circulation.

  • Explain why pulses are bounding and there is a wide pulse pressure in a large PDAPeripheral pulses are bounding as the run-off into the pulmonary circulation drops the diastolic pressure and causes a wide pulse pressure.

Physical examination commonly reveals bounding peripheral pulses, a hyperactive precordium, and tachycardia with or without gallop rhythm

pulse pressure is considered abnormally low if it is less than 25% of the systolic value.

A widened pulse pressure could be a sign of a patent ductus arteriosus in an infant. This is defined as a difference between systolic and diastolic blood pres- sure of greater than 15 to 25 mm Hg, in premature infants and greater than 25 mm Hg in term infants [1].

  • Describe the classic continuous murmur of a PDA

A patent ductus arteriosus causes a continuous murmur since there is a constant pressure gradient in both systole and diastole forcing blood from the aorta into the pulmonary artery. The normal aortic systolic/diastolic pressure is 120/80 mmHg and the normal pulmonary arterial pressure is 25/5 mmHg. Thus in systole there is an average of a 95 mmHg gradient causing a left to right shunt and during diastole there is a 75 mmHg gradient causing a similar shunt.

The murmur of a patent ductus arteriosus is continuous throughout systole and diastole. Often the S2 heart sound is difficult to detect. The murmur begins just after S1 and crescendos peaking at S2, the decrescendos to S1.

PDA

  • Describe radiographic and echocardiographic findings of a PDA

Chest radiographic features may vary depending on whether it is isolated or associated with other cardiac anomalies and with the direction of shunt flow (right to left or left to right). Can have cardiomegaly (predominantly left atrial and left ventricular enlargement if not complicated). Obscuration of the aortopulmonary window and features of pulmonary oedema may be evident.

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Direct visualisation of PDA. Colour Doppler can provide information of the direction of flow.

MDCT can non-invasively provide detailed anatomical information 1.

Krichenko classification based on CT angiography:

  • type A: conical ductus, prominent aortic ampulla with narrowing at pulmonary artery end
  • type B: window, short and wide ductus with blending of pulmonary artery
  • type C: long tubular ductus with no constrictions
  • type D: multiple constrictions with complex ductus
  • type E: elongated ductus with remote constriction

A ductus may have a tortuous morphology that does not fit in the Krichenko classification. This ductus type is usually observed in premature children and some authors proposed to classify it as type F or fetal type. Compared to types A to E, a type F ductus is larger, longer, tapers minimally from the aortic to pulmonary end, with a tortuous connection to the pulmonary artery giving a hockey-stick appearance 9.

  • List potential complications of a PDA

One possible complication of untreated moderate or severe patent ductus arteriosus (PDA) is irreversible damage to the blood vessels of the lungs as a result of prolonged high blood pressure. If the PDA remains untreated, this damage can lead to death, typically in the fourth or fifth decade of life. Another potential complication of PDA is an infection of the blood vessels or heart structures called subacute bacterial endocarditis, which can be life threatening.

  • Describe transcathether PDA closure with a an umbrella-like device or a sac containing several intravascular coils

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Procedure is usually done under general anesthesia, except in adult patient, where sedation with local anesthesia is given. Access in the femoral vein is obtained with placement of a 5-7 F sheath. A 5-F sheath is placed in the femoral artery. Heparin is used according to the operators’ preference. All of our patients were done without heparin.

Main PA pressure and aortic pressure is recorded with pall back gradient from ascending to descending aorta obtained to rule out any obstruction. Angiogram in the lateral projection is then performed with a catheter in the proximal descending aorta to calcify the PDA. The PDA size is measured and the PDA is classified by its shape.[]

The device is selected so that the smaller end is at least 2 mm larger than the narrowest portion of the PDA. An end-hole catheter is passed from the main PA through the PDA into the descending aorta. A stiff exchange guide wire is placed with the tip in the distal descending aorta.

A 5-7F long sheath is then passed over the wire into the descending aorta. The appropriate-sized device is then screwed onto the delivery cable and pulled into the loader under water to prevent air entry into the device or sheath.

The device is then advanced to the tip of the sheath in the descending aorta without rotation of the cable. The sheath and device are then pulled back into a position just distal to the ampulla. The position of the device is confined with repeated angiograms in the descending aorta and adjusted until the retention skirt is well seated in the ampulla.

When good position is achieved, the sheath is retracted further and the tubular part of the device is opened within the PDA.

Another angiogram is performed in the descending aorta to confirm final device position up to this step, the device can be repositioned or retrieved if the angiogram showed significant residual flow; sometime a repeated angiogram is performed in the descending aorta ten minutes after. If device position is satisfactory, the pin vise is then fixed onto the delivery cable, and the device is released with counter-clockwise rotation.

Repeat pull back pressures are obtained from the left PA to the main PA and ascending to descending aorta to evaluate for possible pressure gradient.

The patient receives intravenous antibiotics for 24 hours and usually discharged on second day after evaluation by CXR, and echo-doppler study and kept on oral antibiotic for 5 days.

Observation of subacute bacterial endocarditis prophylaxis is recommended for six months or until complete closure is obtained. Patients are instructed to avoid contact sports for one month.

Follow-up the patient includes clinical evaluation, transthoracic echocardiography and CXR done after one month, six months, and one year after occlusion.

 

Ventricular Septal Defect (VSD)

A 4-month-old infant who has a systolic murmur begins to develop shortness of breath and to perspire while feeding. Weight gain since birth has been poor. Physical examination reveals a holosystolic murmur at the left sternal border and signs of heart failure, including enlargement of the liver and easy fatigability. In addition, there is a diastolic flow murmur caused by increased flow across the mitral valve.

Talking Points

  • Describe VSDs

A ventricular septal defect (VSD) is a hole or a defect in the septum that divides the 2 lower chambers of the heart, resulting in communication between the ventricular cavities. A VSD may occur as a primary anomaly, with or without additional major associated cardiac defects. It may also occur as a single component of a wide variety of intracardiac anomalies, including tetralogy of Fallot (TOF), complete atrioventricular (AV) canal defects, transposition of great arteries, and corrected transpositions.

The term ventricular septal defect refers to an isolated VSD, or a defect in a heart with AV concordance. That is, the atria are attached to the correct ventricle and the normally related arteries (great arteries arising from the appropriate ventricle [ie, an otherwise normal heart]), with no other major lesions. An isolated VSD occurs in approximately 2-6 of every 1000 live births and accounts for more than 20% of all congenital heart diseases. After bicuspid aortic valves, VSDs are the most commonly encountered congenital heart defects.

The symptoms and physical findings associated with ventricular septal defects (VSDs) depend on the size of the defect and the magnitude of the left-to-right shunt, which, in turn, depends on the relative resistances of the systemic and pulmonary circulations (see Presentation).

Children with small VSDs are asymptomatic and have an excellent long-term prognosis. Neither medical therapy nor surgical therapy is indicated. In children with moderate or large VSDs, medical therapy is indicated to manage symptomatic congestive heart failure (CHF) because some VSDs may become smaller with time, although uncontrolled CHF symptoms with growth failure is an indication for surgical repair. Neither the age nor the size of the patient is prohibitive in considering surgery (see Treatment).

For patient education resources, see the Heart Health Center, as well as Tetralogy of Fallot and Ventricular Septal Defect.

  • Discuss the embryologic development of the heart

Image result for embryologic development of the heart

In human embryos the heart begins to beat at about 22-23 days, with blood flow beginning in the 4th week. The heart is therefore one of the earliest differentiating and functioning organs.

The heart begins very early in mesoderm within the trilaminar embryonic disc. The heart forms initially in the embryonic disc as a simple paired tube inside the forming pericardial cavity, which when the disc folds, gets carried into the correct anatomical position in the chest cavity.

A key aspect of heart development is the septation of the heart into separate chambers. As the embryonic/fetal circulation is different to the neonatal circulation (lung/pulmonary activation), several defects of heart septation may only become apparent on this transition. One septal “defect” occurs in us all, the foramen ovale (between the 2 atria) which in general closes in the neonate over time.

  • Describe the influence of the size of the VSD and the level of pulmonary vascular resistance in relation to systemic vascular resistance in determining the magnitude of the shunt

 

 

  • Describe the various pathophysiologic paths that a large VSD may follow, especially if pulmonary blood flow is at least two times systemic blood flow

During ventricular contraction, or systole, some of the blood from the left ventricle leaks into the right ventricle, passes through the lungs and reenters the left ventricle via the pulmonary veins and left atrium. This has two net effects. First, the circuitous refluxing of blood causes volume overload on the left ventricle. Second, because the left ventricle normally has a much higher systolic pressure (~120 mmHg) than the right ventricle (~20 mmHg), the leakage of blood into the right ventricle therefore elevates right ventricular pressure and volume, causing pulmonary hypertension with its associated symptoms.

In serious cases, the pulmonary arterial pressure can reach levels that equal the systemic pressure. This reverses the left to right shunt, so that blood then flows from the right ventricle into the left ventricle, resulting in cyanosis, as blood is by-passing the lungs for oxygenation.[7]

This effect is more noticeable in patients with larger defects, who may present with breathlessness, poor feeding and failure to thrive in infancy. Patients with smaller defects may be asymptomatic. Four different septal defects exist, with perimembranous most common, outlet, atrioventricular, and muscular less commonly.[8]

 

  • Discuss normal cardiac blood flow and chamber pressure profiles

 

  • Describe the clinical manifestations of small and large VSDs

Ventricular septal defects have a very characteristic murmur, to the point where a cardiologist may be able to pinpoint the location and estimate the size of a ventricular septal defect just by how it sounds.

However, a murmur is often not heard at birth. It is only with time and pressure changes that flow across the hole between the pumping chambers can be heard as a murmur.

A smaller hole may actually make a louder noise than a large hole, and the murmur may get louder as the ventricular septal defect closes.

Think of a garden hose. If the water flows freely, it makes a soft sound. If you make the outlet of the hose smaller with your finger, the noise will get louder. It is important to remember a loud murmur does not necessarily mean a large hole.

Babies who do have moderate or large ventricular septal defects with excessive blood flow to the lungs will have signs of congestive heart failure. The most important sign will be the baby’s growth.

Babies who have significant congestive heart failure will have failure to thrive and will have difficulty maintaining a normal weight gain in the first few months of life.

Babies with some extra flow to the lungs may grow well because their ability to feed remains unaffected. They may have some subtle signs of congestive heart failure such as continuous fast breathing.

If a baby grows well in the first few months, it is likely that the ventricular septal defect will not lead to congestive heart failure and the baby can be observed. If the baby does show significant signs of congestive heart failure, the ventricular septal defect may need to be surgically closed.

  • Discuss laboratory procedures used to diagnose VSD, including chest radiography, echocardiography, and color Doppler examination

Most ventricular septal defects can be diagnosed on physical exam, due to their characteristic murmur. The murmur can change with time either due to the hole closing, or in the case of large ventricular septal defects, due to more blood flow across the hole.

The heart can sometimes be seen or felt to be beating hard because of the extra work it is performing. Babies can be continuously breathing fast or hard and have a fast heart rate.

An electrocardiogram can help determine the sizes of the chambers to see if there is strain on the heart due to the ventricular septal defect. However, the electrocardiogram can be normal at birth and change with time as congestive heart failure worsens. It can also suggest if there are other heart defects associated with the ventricular septal defect.

chest X-ray can help follow the progression of congestive heart failure by looking at the size of the heart and the amount of blood flow to the lungs. This may be normal at birth and change with time.

An echocardiogram may need to be performed if the diagnosis is unclear or if there is suspicion of other effects on the heart.

Most small ventricular septal defects will not require an echocardiogram as they tend to close, but often infants with moderate or large ventricular septal defects will need to have at least one echocardiogram to provide the cardiologist with a complete picture of the defect.

Although rare, in some children with ventricular septal defects a cardiac catheterization will need to be performed. This can help the cardiologist determine more accurately how much blood flow is going out to the lungs. This can be very useful in determining the need for surgery in children who have had subtle signs of congestive heart failure but who do not have clear-cut evidence of the need for surgical repair.

 Color flow imaging provides safe, rapid diagnosis of VSD complicating AMI, and may alleviate the need for diagnostic right-sided heart catheterization and preoperative cine ventriculography in these seriously ill patients.

  • Discuss the two goals of treatment for large VSDs

Children with small ventricular septal defects (VSDs) are asymptomatic and have an excellent long-term prognosis. Neither medical therapy nor surgical therapy is indicated. Prophylactic antibiotic therapy against endocarditis is no longer indicated in most cases. Maintenance of good oral hygiene is of paramount importance in reducing the risk of endocarditis.

In children with moderate or large VSDs, medical therapy is indicated to manage symptomatic congestive heart failure (CHF) because some VSDs may become smaller with time.

Uncontrolled CHF with growth failure and recurrent respiratory infection is an indication for immediate surgical repair. Neither the age nor the size of the patient is prohibitive in considering surgery.

Large, asymptomatic defects associated with elevated pulmonary artery (PA) pressure are often repaired when infants are younger than age 6-12 months. Surgical repair is indicated in older asymptomatic children with a normal pulmonary pressure if the pulmonary-to-systemic flow ratio (Qp:Qs) is large enough to result in left ventricular dilatation on echocardiography.

Prolapse of an aortic valve cusp is an indication for surgery even if the VSD is small. Early repair may prevent progression of the aortic valve insufficiency.

Early surgical repair (younger than age 1 year) of VSD appears to lead to a significant postsurgical acceleration of growth within 3-6 months in term and preterm infants and, thus, a favorable growth pattern. [15However, patients who undergo a rapid postsurgery catch-up growth after a period of failure to thrive may have an increased risk of insulin resistance, metabolic syndrome, obesity, and cardiovascular disease. [15]

Elevated pulmonary vascular resistance may be maintained in some patients despite VSD closure and may, in fact, represent a primary disease of the pulmonary vessels.

  • Discuss Eisenmenger syndrome

Eisenmenger syndrome refers to any untreated congenital cardiac defect with intracardiac communication that leads to pulmonary hypertension, reversal of flow, and cyanosis. [123The previous left-to-right shunt is converted into a right-to-left shunt secondary to elevated pulmonary artery pressures and associated pulmonary vascular disease. (See EtiologyTreatment, and Medication.)

Lesions in Eisenmenger syndrome, such as large septal defects, are characterized by high pulmonary pressure and/or a high pulmonary flow state. Development of the syndrome represents a point at which pulmonary hypertension is irreversible and is an indication that the cardiac lesion is likely inoperable (see the image below). (See EtiologyTreatment, and Medication.) Cardiac arrhythmias and sudden cardiac death are important late complications of this syndrome. Conservative management with medications and/or lung and cardiac transplantation are therapeutic approaches that can offer quality-of-life improvement.

  • Describe the prognosis of VSD after surgical repair

 Long-term results of ventricular septal defect (VSD) repair are favorable. In the absence of pulmonary vascular disease, infants who undergo VSD repair within the first 1-2 years of life are considered cured and demonstrate improved physical development (growth and weight gain), as well as normal long-term ventricular function. Most long-term survivors are asymptomatic and lead normal lives. Vasoactive-inotropic score (VIS) after surgery may be useful as a predictor of outcomes. One prospective study of 70 infants undergoing cardiothoracic surgery found that a higher VIS is associated with increased length of ventilation, and prolonged ICU and total hospital stay. [19]

Exercise tolerance may be diminished. If congestive heart failure and cardiomegaly are well established and repair has been undertaken late in life, postoperative symptoms, including exercise intolerance, are more common. Premature late death is rare (< 2.5%) in patients with low preoperative pulmonary vascular resistance. Patients with preoperative pulmonary vascular disease may develop severe, life-threatening pulmonary hypertension.

 

Week six, Day two:

 

Coarctation of the Aorta

A newborn infant is noted to develop respiratory distress 2 days after birth. On examination, her skin is mottled and she has weak upper extremity pulses and no femoral pulses. Arterial blood gases show a profound metabolic acidosis, which is predominantly due to accumulation of lactic acid.

Image result for aortic coarctationImage result for aortic coarctation

Talking Points

  • Describe the three types of aortic coarctation

 

There are three types of aortic coarctations:
  • Preductal coarctation: The narrowing is proximal to the ductus arteriosus. …
  • Ductal coarctation: The narrowing occurs at the insertion of the ductus arteriosus.
  • Postductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus.
  • Image result for Ductal coarctation

Image result for Preductal coarctation

  • Discuss metabolic acidosis

Metabolic acidosis is a condition that occurs when the body produces excessive quantities of acid or when the kidneys are not removing enough acid from the body. If unchecked, metabolic acidosis leads to acidemia, i.e., blood pH is low (less than 7.35) due to increased production of hydrogen ions by the body or the inability of the body to form bicarbonate (HCO3) in the kidney. Its causes are diverse, and its consequences can be serious, including coma and death. Together with respiratory acidosis, it is one of the two general causes of acidemia.

Terminology :

  • Acidosis refers to a process that causes a low pH in blood and tissues.
  • Acidemia refers specifically to a low pH in the blood.

In most cases, acidosis occurs first for reasons explained below. Free hydrogen ions then diffuse into the blood, lowering the pH. Arterial blood gas analysis detects acidemia (pH lower than 7.35). When acidemia is present, acidosis is presumed.

  • Discuss the hypertension associated with post-ductal coarctation

Postductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus. Even with an open ductus arteriosus, blood flow to the lower body can be impaired. This type is most common in adults. It is associated with notching of the ribs (because of collateral circulation), hypertension in the upper extremities, and weak pulses in the lower extremities. Postductal coarctation is most likely the result of the extension of a muscular artery (ductus arteriosus) into an elastic artery (aorta) during fetal life, where the contraction and fibrosis of the ductus arteriosus upon birth subsequently narrows the aortic lumen.[6]

  • Describe the classic sign of coarctation of the aorta

Signs and symptoms

  • Early life

    Depending on severity of the obstruction and associated cardiac lesions, patients with aortic coarctation may present with congestive heart failure, severe acidosis, or poor perfusion to the lower body. [10]

    Newborns typically present with severe narrowing of the upper thoracic aorta below the isthmus and adjacent to the arterial duct. [7]

    Beyond infancy

    Patients are usually asymptomatic. They may present with hypertension, headache, nosebleed, leg cramps, muscle weakness, cold feet, or neurologic changes.

    The diagnosis of coarctation generally can be made on the basis of physical examination. Blood pressure differential and pulse delay are pathognomonic. The following physical findings may be noted:

    • Frequently normal physical appearance (except when coarctation compromises the origin of the left subclavian artery or in cases of XO Turner syndrome)

    • Abnormal differences in upper- and lower-extremity arterial pulses and blood pressures; diminished and delayed pulses distal to obstruction

    • Characteristic murmurs and sounds on auscultation (eg, continuous or late systolic murmur posteriorly over the thoracic spine, bilateral collateral arterial murmurs, aortic ejection sound, short midsystolic murmur, or early diastolic murmur of aortic regurgitation)

    • Associated cardiac defects (eg, left-side obstructive or hypoplastic defects and ventricular septal defects, bicuspid aortic valve, aortic arch hypoplasia, and, rarely, various right-side cardiac obstructive lesions)

    • Extracardiac vascular anomalies (eg, aberrant subclavian artery, berry aneurysms of the circle of Willis, development of large upper-to-lower collateral arteries, or hemangiomas)

    • Extracardiac nonvascular anomalies (eg, head and neck, musculoskeletal, gastrointestinal, genitourinary, or respiratory)

  • Describe testing for radial-femoral delay

The coarctation typically occurs after the left subclavian artery. However, if situated before it, blood flow to the left arm is compromised and asynchronous or radial pulses of different “strength” may be detected (normal on the right arm, weak or delayed on the left), termed radio-radial delay. In these cases, a difference between the normal radial pulse in the right arm and the delayed femoral pulse in the legs (either side) may be apparent, whilst no such delay would be appreciated with palpation of both delayed left arm and either femoral pulses. On the other hand, a coarctation occurring after the left subclavian artery will produce synchronous radial pulses, but radio-femoral delay will be present under palpation in either arm (both arm pulses are normal compared to the delayed leg pulses).

  • Discuss the diagnosis of coarctation and notching of the interior border of the ribs from pressure exerted by enlarged collateral vessels

The enlarged left subclavian artery commonly produces a prominent shadow in the left superior mediastinum. Notching of the inferior border of the ribs from pressure erosion by enlarged collateral vessels is common by late childhood. In most instances, an area of poststenotic dilatation of the descending aorta is present.

  • Describe the use of prostaglandin E1 to reopen the ductus

Alprostadil (PGE1) is a naturally occurring prostaglandin that was approved by the Food and Drug Administration (FDA) in 1981 for use in infants with CHD that required maintenance of ductal patency until palliative or corrective surgery could be performed (Roehl 1982). PGE1 is often used in neonates with prenatally diagnosed ductus-dependent cardiac disease in the immediate postnatal period (Marino 2001Penny 2001Shivananda 2010). Since 60% to 80% of PGE1 is metabolized on first pass through the lungs, it must be administered by continuous infusion.

  • Describe surgical approaches to correct coarctation

The standard approach for coarctation – particularly when identified in neonates and younger patients – is surgical. On occasion, nonsurgical, catheter-based interventions are used.

There are no medications that can help resolve coarctation. Sometimes medicines are used to reduce the effects of coarctation, specifically to treat high blood pressure or related heart problems. Yet even in those circumstances, medical therapy is typically done in concert with surgical therapy. At the same time, less-invasive, catheter-based interventions have been developed to treat some cases of coarctation.

Typically, in the newborn period, if there is significant narrowing of the coarctation, immediate operation is recommended. If there are extenuating circumstances that increase the risk of surgery, and the child appears to have at most a mild to moderate degree of coarctation, we would consider delaying the operation until the risk is reduced. Alternatively, if there are other heart-related conditions that required surgical therapy, these might influence the decision to proceed with surgery.

The standard approach for discrete aortic narrowing is via an incision between the ribs on the left side of the chest. The aorta sits very far back in the chest cavity next to the spine. Surgeons spread the ribs apart, push the lung out of the way, open up the lining inside the chest that overlies the aorta and, after exposing the aorta, isolate the segment of narrowing between clamps. They then cut out the segment and sew the two ends of the aorta together, usually overlapping the segments to address any milder narrowing of the adjacent segments of the aorta.

The operation usually takes 2-3 hours. The portion of the operation in which the segment is cut out and the two ends are brought together is typically 15-20 minutes. A small amount of blood thinner called heparin is given to prevent clot formation downstream from where the aorta is clamped.

For the 15-20 minutes during which the segment of narrowing is isolated, there may be decreased perfusion to the lower part of the body and increased perfusion, or higher pressure, to the upper part of the body. The lower body is typically adequately supported with blood for this short period via the collateral blood vessels described previously.  Our anesthesiologists are trained in managing children’s cases and know how to ensure the patient is well protected during the operation.

There are variations of how the two portions of the aorta are connected depending on the degree of underdevelopment of the upstream portion of the aorta. If the narrowing is discrete, and the degree of underdevelopment is minimal, then the extent that the lower aorta is brought up and attached to the underside of the arch is pretty minimal. On the other hand, if there is more extensive narrowing, a larger portion of the aorta is opened up or sometimes the aorta is patched, typically with a native blood vessel that takes blood to the left arm.

  • Describe the prognosis for coarctation

The most significant risk of coarctation repair, although not a very high one, is that of re-coarctation, or re-narrowing. This can occur in anywhere from 2-10% of children after coarctation surgery, with statistics indicating the risk of re-narrowing is greater in younger children. Historical data suggest that babies under three months of age had a 25% incidence of re-coarctation. More current experience suggests a lower incidence of around 2-5%.

Fortunately, the vast majority of re-coarctations can be treated with a catheter-based approach (balloon angioplasty). This approach is typically not used as the primary treatment for significant coarctation because of the complications that can develop from using a catheter on a native coarctation. However, once a repair has been done, balloon angioplasty is quite effective in treating re-coarctations that occur at the site of the scar tissue.

  • Describe the PHACE syndrome

PHACE syndrome (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies, and eye anomalies) is an uncommon disorder of unknown etiology characterized by large segmental hemangiomas of the face and various developmental defects. The term “PHACE(S)” is sometimes used in the presence of ventral developmental defects, which include sternal cleft, supraumbilical raphe, or both.

Image result for PHACE syndrome

  • Describe serious complications of coarctation arising from systemic hypertension and the risk of infective endocarditis

Survival of patients with aortic coarctation improved dramatically after surgical repair became available and the number of patients who undergo surgery and reach adulthood is steadily increasing. However, life expectancy is still not as normal as in unaffected peers. Cardiovascular complications are frequent and require indefinite follow-up. Concern falls chiefly into five categories: recoarctation, endocarditis, stenotic and/or incompetent coexisting bicuspid aortic valve, aortic aneurysm formation and systemic hypertension.

In patients after repair of aortic coarctation, endocarditis
can occur either at the site of repair or – more
often – at an associated abnormal aortic valve. The
overall risk of infective endocarditis in the group of
operated and non operated patients together is moderate
to low and appears to increase with age or time after
surgery.’8″9 The cumulative incidence of infective
endocarditis in patients after successful surgical repair
of aortic coarctation is 0.8±0.4% at one year, slowly
increasing to 3.5±1.6% at 30 years of follow-up.8

 

 

Tetralogy of Fallot

One day after birth, a male infant is noted to have cyanosis of the oral mucosa and of the extremities. Pulses are normal. A grade III systolic murmur, best heard at the LSB, is believed to be caused by turbulence occurring in the right ventricular outflow tract. Two-dimensional echocardiography establishes the diagnosis of Tetralogy of Fallot.

Talking Points

  • Review the four components of the tetralogy of Fallot
  • A large ventricular septal defect (VSD)
  • Pulmonary (PULL-mun-ary) stenosis.
  • Right ventricular hypertrophy (hi-PER-tro-fe)
  • An overriding aorta.

The 4 abnormalities (tetralogy) of the heart described by Fallot include the following:

  • Right ventricular hypertrophy: Narrowing or blockage of the pulmonary valve and/or muscle under the pulmonary valve coming out of the right ventricle. This restriction to blood outflow causes an increase in right ventricular work and pressure, leading to right ventricular thickening or hypertrophy.
  • Ventricular septal defect (VSD): This is a hole in the heart wall (septum) that separates the 2 ventricles. The hole is usually large and allows oxygen-poor blood in the right ventricle to pass through, mixing with oxygen-rich blood in the left ventricle. This poorly oxygenated blood is then pumped out of the left ventricle to the rest of the body. The body gets some oxygen, but not all that it needs. This lack of oxygen in the blood causes cyanosis.
  • Abnormal position of the aorta: The aorta, the main artery carrying blood out of the heart and into the circulatory system, exits the heart from a position overriding the right and left ventricles. (In the normal heart, the aorta exits from the left ventricle.) This is not of major importance in infants.
  • Pulmonary valve stenosis (PS): The major issue with tetralogy of Fallot is the degree of pulmonary valve stenosis, since VSD is always present. If the stenosis is mild, minimal cyanosis occurs, since blood still mostly travels to the lungs. However, if the PS is moderate to severe, a smaller amount of blood reaches the lungs, since most is shunted right-to-left through the VSD.

Image result for components of the tetralogy of Fallot

  • Explain how blood is shunted when the right ventricle contracts in the presence of marked pulmonary stenosis

 

  • Discuss the systemic hypoxemia and cyanosis

Tet spells are cyanotic and hypoxic episodes that occur in patients with tetralogy of Fallot. The pathophysiology is thought to be related to a change in the balance of systemic-to-pulmonary vascular resistance. Spells may be initiated by events that cause a decrease in systemic vascular resistance (e.g., fever, crying, hypotension) or by events that cause an increase in pulmonary outflow tract obstruction. Both types of events lead to more right-to-left shunting and increased cyanosis. Hypoxia and cyanosis can result in metabolic acidosis and systemic vasodilation, which cause a further increase in cyanosis. Anemia may be a predisposing factor. Although most episodes are self-limited, a prolonged Tet spell can lead to stroke or death; therefore, a spell is an indication for surgery.

Hypertrophy of the right ventricular myocardium is secondary to pressure overload. The large, nonrestrictive VSD and the outflow obstruction result in a right ventricular pressure at systemic levels, while the pulmonary artery systolic pressure is low. Increasing severity of right ventricular outflow tract obstruction or decreases in systemic vascular resistance exacerbate right-to-left intracardiac shunting and systemic arterial desaturation, increasing the level of cyanosis. These are all features that characterize hypercyanotic episodes or “tetralogy (tet) spells” (discussed earlier).

  • Review the various clinical manifestations of tetralogy of Fallot

Image result for clinical manifestations of tetralogy of fallot

Image result for clinical manifestations of tetralogy of fallot

  • Discuss “tet” spells, also known as paroxysmal hypercyanotic attacks

Tet spells are cyanotic and hypoxic episodes that occur in patients with tetralogy of Fallot. The pathophysiology is thought to be related to a change in the balance of systemic-to-pulmonary vascular resistance. Spells may be initiated by events that cause a decrease in systemic vascular resistance (e.g., fever, crying, hypotension) or by events that cause an increase in pulmonary outflow tract obstruction. Both types of events lead to more right-to-left shunting and increased cyanosis. Hypoxia and cyanosis can result in metabolic acidosis and systemic vasodilation, which cause a further increase in cyanosis. Anemia may be a predisposing factor. Although most episodes are self-limited, a prolonged Tet spell can lead to stroke or death; therefore, a spell is an indication for surgery.

  • Explain how squatting relieves paroxysmal hypercyanotic attacks

Image result for clinical manifestations of tetralogy of fallot

  • Describe radiographic and echocardiographic findings of Tetralogy of Fallot

Tetralogy of Fallot is the most common type of cyanotic congenital heart disease. It consists of a right ventricular outflow tract obstruction, a malalignment ventricular septal defect, an overriding aorta, and right ventricular hypertrophy, as demonstrated in the image below.

Radiography

On radiographs, the cardiac silhouette in patients with tetralogy of Fallot is normal in size; however, right ventricular hypertrophy can elevate the left ventricle. Combined with a small or absent main pulmonary artery segment, the heart can have the classic boot-shaped appearance (as seen in the image below). Most children with tetralogy of Fallot do not have boot-shaped heart.

Radiograph of a boot-shaped heart in an infant wit

Radiograph of a boot-shaped heart in an infant with tetralogy of Fallot.

Typically, the appearance of the vascularity of the pulmonary artery is reduced, but it can also be normal. Decreased pulmonary vascularity is frequently difficult for the general radiologist to appreciate. Large collaterals may give the appearance of normal vascularity.

The enlarged aorta in children with a right-sided arch can cause airway compression that can be identified on chest radiographs, as demonstrated in the images below. A right-sided arch is present in 25% of children with tetralogy of Fallot, and it can be identified by means of direct visualization, with displacement of the trachea to the left or with increased opacity of the spinal pedicles on the ipsilateral side of the aortic arch. The position of the aortic arch influences surgical planning because Blalock-Taussig shunts are more easily placed on the contralateral side of the aortic arch. Modified Blalock-Taussig shunts can be placed bilaterally.

Radiograph of an infant with tetralogy of Fallot aRadiograph of an infant with tetralogy of Fallot and a right-sided aortic arch.

Radiograph of an infant with tetralogy of Fallot (Radiograph of an infant with tetralogy of Fallot (same patient as in the previous image). Note the anterior compression of the trachea by the large ascending aorta.

  • Review potential serious complications of tetralogy, which used to occur with increased frequency before the age of corrective surgery

Untreated, tetralogy of Fallot rapidly results in progressive right ventricular hypertrophy due to the increased resistance caused by narrowing of the pulmonary trunk. This progresses to heart failure which begins in the right ventricle and often leads to left heart failure and dilated cardiomyopathy. Mortality rate depends on the severity of the tetralogy of Fallot. If left untreated, TOF carries a 35% mortality rate in the first year of life, and a 50% mortality rate in the first three years of life. Untreated TOF also causes delayed growth and development, including delayed puberty.[citation needed]

  • Describe steps one can take to prevent premature closure of the ductus arteriosus in a neonate with marked right ventricular outflow tract obstruction

 

  • Briefly describe corrective surgical therapy and palliation with a Blalock-Taussig shunt

he Blalock–Thomas–Taussig shunt (commonly called the Blalock–Taussig shunt) is a surgical procedure used to increase pulmonary blood flow for palliation-(alleviation) in duct dependent cyanotic heart defects like pulmonary atresia, which are common causes of blue baby syndrome. In modern surgery, this procedure is temporarily used to direct blood flow to the lungs and relieve cyanosis while the infant is waiting for corrective or palliative surgery.

One branch of the subclavian artery or carotid artery is separated and connected with the pulmonary artery. The first area of application was tetralogy of Fallot.

  • Describe prognosis after total correction

Untreated, tetralogy of Fallot rapidly results in progressive right ventricular hypertrophy due to the increased resistance caused by narrowing of the pulmonary trunk. This progresses to heart failure which begins in the right ventricle and often leads to left heart failure and dilated cardiomyopathy. Mortality rate depends on the severity of the tetralogy of Fallot. If left untreated, TOF carries a 35% mortality rate in the first year of life, and a 50% mortality rate in the first three years of life. Untreated TOF also causes delayed growth and development, including delayed puberty.[citation needed]

Patients who have undergone total surgical repair of tetralogy of Fallot have improved hemodynamics and often have good to excellent cardiac function after the operation with some to no exercise intolerance (New York Heart Association Class I-II). Surgical success and long-term outcome greatly depend on the particular anatomy of the patient and the surgeon’s skill and experience with this type of repair.[citation needed]

Ninety percent of people with total repair as babies develop a progressively leaky pulmonary valve later in life. It is recommended that they follow up at a specialized adult congenital heart disease center.[citation needed]

 

 

Transposition of the great arteries (TGA)

Talking Points

  • Describe the abnormal anatomy in transposition of the great arteries (TGA)

Transposition of the great vessels (TGV) is a group of congenital heart defects involving an abnormal spatial arrangement of any of the great vesselssuperior and/or inferior venae cavaepulmonary arterypulmonary veins, and aorta. Congenital heart diseases involving only the primary arteries (pulmonary artery and aorta) belong to a sub-group called transposition of the great arteries.

Image result for transposition of the great arteries

  • Discuss the circuitry of TGA

 

  • Discuss the course of blood flow in TGA

See above

In the most common form of TGA (d-TGA, complete transposition, or simple transposition), the aorta arises from the right ventricle anteriorly and slightly rightward of the pulmonary artery, which arises from the left ventricle. Desaturated blood returns to the right ventricle and is recirculated to the body via the aorta, while oxygenated blood returns to the left ventricle and is recirculated to the lungs. The end result is separate, parallel circulations (Figure 55-5). Survival is dependent on communication between the two circulations, typically in the form of bidirectional shunting at the patent foramen ovale (PFO) and PDA. With absent or small communications between the circulations, severe systemic acidosis and hypoxia develop after birth, resulting in death.

  • Describe the use of prostaglandin E1 to maintain patency of the ductus arteriosus

Prostaglandins and the ductus arteriosus.

Abstract

Fetal patency of the ductus arteriosus is an active state maintained by the relaxant action of a prostaglandin, most probably prostaglandin E2. This PG mechanism is most active in the immature ductus and decreases toward term. The ductus closes when this prostaglandin effect if withdrawn. Indomethacin may induce closure of the patent ductus arteriosus of prematurity. It is most likely to be successful if given intravenously and early in postnatal life. Prostaglandin E1, to maintain patency of the ductus, is now established in the emergency management of several congenital heart defects causing problems in the newborn.

  • Describe the Rashkind balloon atrial septostomy

Atrial septostomy is a surgical procedure in which a small hole is created between the upper two chambers of the heart, the atria. This procedure is primarily used to treat dextro-Transposition of the great arteries or d-TGA (often imprecisely called transposition of the great arteries), a life-threatening cyanotic congenital heart defect seen in infants. Atrial septostomy has also seen limited use as a surgical treatment for pulmonary hypertension.[1]One common technique was developed in 1966 by American cardiologist William Rashkind at the Children’s Hospital of Philadelphia. The first atrial septectomy was developed by Vivien Thomas in a canine model and performed in humans by Alfred Blalock.

The Rashkind balloon atrial septostomy is performed during cardiac catheterization (heart cath), in which a balloon catheter is used to enlarge a foramen ovalepatent foramen ovale (PFO), or atrial septal defect (ASD) in order to increase oxygen saturation in patients with cyanotic congenital heart defects (CHDs). It was developed in 1966 by American surgeons William Rashkind and William Miller at the Children’s Hospital of Philadelphia.

  • Describe the arterial switch (Jatene) procedure, and why it is usually performed within the first 2 weeks of life

The Jatene procedurearterial switch operation or arterial switch, is an open heart surgical procedure used to correct dextro-transposition of the great arteries (d-TGA);

This surgery may be used in combination with other procedures for treatment of certain cases of double outlet right ventricle (DORV) in which the great arteries are dextrotransposed.

 

  • Describe transposition of the great arteries with small and large ventricular septal defects and the role of echocardiography in diagnosis

The successful diagnosis, surgical planning, and long-term care of children with transposition of the great arteries require high-quality cardiac imaging with echocardiography. Echocardiography must identify the relevant anatomic variants of transposition of the great arteries, such as of ventricular septal defects and aortic arch anomalies. Methodical and detailed imaging of the coronary arteries is particularly important, as translocation of the coronary arteries is a critical component of the arterial switch procedure. Familiarity with the potential coronary artery variants and the ideal imaging planes is essential for an echocardiographer. Knowledge of both the early and late complications following the arterial switch procedure is essential to optimise post-operative echocardiography. These complications can include residual lesions leading to haemodynamic compromise or progressive late phenomena, such as aortic root dilatation and aortic insufficiency. Echocardiography will continue to be the cornerstone to the lifelong management of transposition of the great arteries, and improvements in technology and increased familiarity with modalities such as stress echocardiography will enhance the role of advanced imaging even further.

  • Assessment of the atrial septum and ductus arteriosus

Determining the adequacy of cardiac mixing is one of the most important components of the initial evaluation in the neonate with TGA. The atrial septum is optimally examined on subxiphoid imaging to assess the presence and size of the communication. Color flow imaging provides information on the direction and magnitude of the atrial level shunting (Video 9), and spectral Doppler allows for the determination of the mean pressure gradient across the interatrial septum. The PDA can be examined from parasternal and suprasternal notch imaging to determine its patency, size, and flow (Video 10).

  • Describe l-transposition of the great arteries, with the RA connected to the LV and the LA to the RV (ventricular inversion)

Levo- or L-looped transposition of the great arteries (L-TGA) is a rare form of congenital heart disease characterized by atrioventricular and ventriculoarterial discordance. It is also commonly referred to as congenitally corrected TGA, double discordance, or ventricular inversion.

L-TGA usually does not present with cyanosis unless there are associated cardiac defects. Isolated L-TGA is “physiologically corrected” because systemic deoxygenated venous blood returns to the pulmonary circulation and oxygenated pulmonary venous blood returns to the systemic circulation. Patients with L-TGA are at increased risk for heart failure as adults due to progressive decline in systemic right ventricular function.

  • Describe total anomalous pulmonary venous return in which there is no direct pulmonary venous connection into the LA

 

  • Describe truncus arteriosus, in which a single trunk arises from the heart and supplies the systemic, pulmonary, and coronary circulations

Truncus arteriosus is a rare type of heart disease in which a single blood vessel (truncus arteriosus) comes out of the right and left ventricles, instead of the normal 2 vessels (pulmonary artery and aorta). It is present at birth (congenital heart disease).

There are different types of truncus arteriosus.

Causes

In normal circulation, the pulmonary artery comes out of the right ventricle and the aorta comes out of the left ventricle, which are separate from each other.

With truncus arteriosus, a single artery comes out of the ventricles. There is most often also a large hole between the 2 ventricles (ventricular septal defect). As a result, the blue (without oxygen) and red (oxygen-rich) blood mix.

Some of this mixed blood goes to the lungs, and some goes to the rest of the body. Often, more blood than usual ends up going to the lungs.

If this condition is not treated, two problems occur:

  • Too much blood circulation in the lungs may cause extra fluid to build up in and around them. This makes it hard to breathe.
  • If left untreated and more than normal blood flows to the lungs for a long time, the blood vessels to the lungs become permanently damaged. Over time, it becomes very hard for the heart to force blood to them. This is called pulmonary hypertension, which can be life threatening.
  • Describe clinical manifestations and echocardiographic findings of truncus arteriosus

 

  • Describe hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped. It may affect the left ventricleaortaaortic valve, or mitral valve.[1

At birth, the ductus arteriosus is still open, and there is higher than normal resistance to blood flow in the lungs. This allows for adequate oxygenation via mixing between the atria and a normal appearance at birth. When the ductus begins to close and pulmonary vascular resistance decreases, blood flow through the ductus is restricted and flow to the lungs is increased, reducing oxygen delivery to the systemic circulation. This results in cyanosis and respiratory distress which can progress to cardiogenic shock. The first symptoms are cyanosis that does not respond to oxygen administration or poor feeding. Peripheral pulses may be weak and extremities cool to the touch.[2]

  • Describe the clinical manifestations of hypoplastic left heart syndrome

Image result for clinical manifestations of hypoplastic left heart syndrome

Image result for clinical manifestations of hypoplastic left heart syndrome

Hypoplastic Left Heart Syndrome (HLHS) | Symptoms & Causes
  • rapid breathing or shortness of breath.
  • rapid heartbeat or pounding heart.
  • poor suckling and feeding.
  • cold extremities (poor perfusion)
  • blue color of the skin, lips and nailbeds (cyanosis)
  • weakness.
  • Briefly describe the three stages of the Norwood procedure

Stage 1

This procedure is performed shortly after birth. It converts the right ventricle into the main ventricle pumping blood to both the lungs and the body. The main pulmonary artery and the aorta are connected and the main pulmonary artery is cut off from the two branching pulmonary arteries that direct blood to each side of the lungs. Instead, a connection called a shunt is placed between the pulmonary arteries and the aorta to supply blood to the lungs.

Stage 2 (Bi-directional Glenn Operation)

This operation usually is performed about six months after the Norwood to divert half of the blood to the lungs when circulation through the lungs no longer needs as much pressure from the ventricle. The shunt to the pulmonary arteries is disconnected and the right pulmonary artery is connected directly to the superior vena cava, the vein that brings deoxygenated blood from the upper part of the body to the heart. This sends half of the deoxygenated blood directly to the lungs without going through the ventricle.

Stage 3 (Fontan Operation)

This is the third stage, usually performed about 18 to 36 months after the Glenn. It connects the inferior vena cava, the blood vessel that drains deoxygenated blood from the lower part of the body into the heart, to the pulmonary artery by creating a channel through or just outside the heart to direct blood to the pulmonary artery. At this stage, all deoxygenated blood flows passively through the lungs.

Image result for three stages of the Norwood procedure

 

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