CVM W11 – Congenital Heart Defects PDF

DONE INTRODUCTORY SESSION Contact Dr Anupama Bangrakulur Congenital Heart Defects Contact Hours Via email and during the GLS session.. Key Words Development of the heart Septation Septum primum Septum secondum Truncus arteriosus Foetal circulation Foramen ovale Ductus arteriosus Cyanosis Obstruction...

DONE INTRODUCTORY SESSION Contact Dr Anupama Bangrakulur Congenital Heart Defects Contact Hours Via email and during the GLS session.. Key Words Development of the heart Septation Septum primum Septum secondum Truncus arteriosus Foetal circulation Foramen ovale Ductus arteriosus Cyanosis Obstructions and shunt Acyanotic defects Cyanotic defects Congenital aortic stenosis Atrial septal defect Ventricular septal defect Coarctation of the Aorta Eisenmenger syndrome Patent ductus arteriosus Prostaglandins Congenital Pulmonic stenosis Jatene procedure Tetrology of Fallot Tet spells Transposition of the great vessels Persistent truncus arteriosus.. Preparation. Review the general anatomy, development of heart, foetal circulation and physiology of the heart and circulation (Weeks 1-9). Introduction to Congenital Heart Defects is covered in two parts. Please watch ‘Introductory lecture part – 1’ posted on LearnJCU in the week 11 CVM folder before you attend the lecture on Wednesday May 8th... Learning Overview Congenital heart defects occur due to the abnormalities during the development of the heart. While the primary pathologies of congenital heart defects are abnormal shunting of the blood or obstruction to the normal blood flow, the presence or absence of cyanosis is a useful clinical detection. Most common congenital defects observed clinically include septal defects, patent ductus arteriosus, Tetrology of Fallot, Transposition of the great vessels, aortic stenosis, pulmonary stenosis and coarctation of the aorta. Though some of the mild to moderate congenital heart defects may heal over the time many defects require correction either by invasive or non-invasive methods.... GUIDED LEARNING SESSION Contact Dr Anupama Bangrakulur Congenital Heart Defects Contact Hours Via email and during the GLS session... Preparation Review Cardiovascular material from previous weeks. In this session you will work through your workbook which provides questions to a number of cases relevant to congenital heart defects.. Learning Overview  The cases provided in this week’s workbook are designed to help your understanding of congenital heart defects. In addition to being able to define the various congenital heart defects discussed in this week’s lecture, it is important for you to consider how each defect might affect the cardiac cycle and as such cardiac output. The main point is for you to understand the physiological implication of each of the defects discussed. Please keep in mind; due to time constraints we have only scraped the surface in terms of the different congenital heart defects. Over the course of your profession you will come across defects that have not been discussed in this weeks lecture as such it is important for you to readthrough the literature familiarising yourself with other potential defects. We have addressed those which are most common. Organisation Review questions on the cases given in GLS workbook using Introductory Session material and the relavant textbooks. Utilise this session as an opportunity to seek clarification on any concepts from the ‘Introductory Session’ that may not have been fully understood. SYNTHESISING SESSION Contact Dr Anupama Bangrakulur Congenital Heart Defects Contact Hours Via email and during the GLS session... Preparation Review the development of heart, foetal circulation and changes at birth. Revise Introductory Lecture and GLS.. Please send any questions or inquerries you have regarding the common ‘Congenital Heart Defects’ that were not clarified during the lecture sessions or in the GLS sessions prior to this session via email. These will be addressed and discussed during this session. Learning Overview Clarification of Eisenmenger’s Syndrome, clinical manifestations of congenital defects, approaches to the treatment of congenital heart defects.. Organisation A Power Point slide presentation will incorporate responses to GLS workbook, responses to common queries of students during the GLS session and answers to questions received via email. Learning Activities Discussion/question session. After we conclude this session, please don’t hesitate to email any questions or querries you have regarding concepts that weren’t clear this week... MD2011 Cardiovascular Medicine Pathophysiology of Congenital Heart Defects Anu [email protected] Learning Objectives o describe briefly the development of the heart and great vessels during organogenesis o explain the fetal circulation and the changes that occur to establish postpartum circulation o discuss congenital heart defects that arise from shunts, explaining why a right-to-left shunt is more serious than a left-to-right shunt o describe how congenital heart defects with left-to-right shunt left untreated could result in Eisenmenger’s Syndrome (including its common symptoms) o discuss congenital heart defects that arise from obstructions o explain how a child could become cyanotic due to the congenital heart defect Learning Objectives  for each of the following congenital heart defects, describe the pathology, explain how the symptoms arise, and the basis for the specific treatment(s) to address the symptoms and/or the pathology.  atrial and ventricular septal defects  patent ductus arteriosus  congenital pulmonary valve stenosis and congenital aortic valve stenosis  coarctation of the aorta  tetralogy of Fallot  transposition of the great arteries  persistent truncus arteriosus Congenital Heart Defects o abnormalities present from birth (≈ 8 out of 1,000 live births) o most common heart disorder in children o clinical manifestations depends on the severity of defect o survival of children with congenital heart disease has improved dramatically o prenatal diagnosis and early intervention now possible o may require lifelong guidance regarding physical activity, pregnancy and employment Congenital Heart Defects  most abnormalities are due to problems associated with:  development of the atrial septum  development of the ventricular septum  division of the main outflow tract - the truncus arteriosus into the pulmonary artery and aorta  development of the valves  common for multiple defects to be present in one child Development of the Heart Sinus venosus Development of Heart - Septation Septation Defects include Septal development of the heart Diagrammatic representation: flap-type valve of the foramen ovale. o atrial septal defects o ventricular septal defects o atrioventricular valve defects Development of Major Arteries Defects in the development of major arteries results in, o o o persistent truncus arteriosus transposition of the great arteries congenital aortic and pulmonic valve defects Figure 18-24, Copstead and Banasik Key points in Cardiogenesis o The heart is the first functioning organ in the embryo - starts functioning by the end of 3 rd week o Cardiogenesis: Begins with the mesodermal cells forming pair of endocardial tubes. Tubes fuse to form a single tube (Atrioventricular canal). From inside to outside, the layers of this tube are an endothelial lining that becomes the endocardium, a layer of gelatinous connective tissue and a thick mesodermal origin mesenchymal layer that develops into the myocardium. o By approximately the 28th day - series of constrictions and looping of this tube result in primitive heart structures that include a common atrium; a common ventricle; the sinus venosus, which eventually evolves into the superior and inferior venae cavae; the bulbus cordis, which eventually evolves into the ventricular outflow tracts; and the truncus arteriosus, which eventually yields the main pulmonary artery and aorta  Development of valves, septation of atria, ventricles and ventricular outflow tracts occurs between 4 th to 7th week of embryonic life. Key points in Cardiogenesis  Endocardial cushions begin as swellings of the gelatinous connective tissue layer within the atrioventricular canal play important role in the development of heart's valves and septa critical to the proper formation of a four-chambered heart.  Atrial septation includes development of septum primum and septum secondum. Septum secondum has an oval shaped opening –foramen ovale i.e., covered by septum primum that act as a valve allowing blood flow from right to left in foetal life.  Primitive muscular interventricular septum located in the median region of the primitive ventricle grows to meet the membranous portion of the endocardial cushions to form interventricular septum.  Subendocardial mesenchymal tissue proliferates and develops to form atrioventricular and semilunar valves  A pair of mesenchymal derived bulbar ridges fuse and undergo spiraling process, divides bulbus cordis and the truncus arteriosus into pulmonary artery and the aorta Foetal Circulation  lungs are collapsed, offering high resistance to pulmonary blood flow (low arterial PO 2 = 30 to 35 mmHg)  oxygenation is via the placenta  blood shunts from the right atrium (RA) to the left atrium (LA) by the foramen ovale  blood shunts from the pulmonary artery to the aorta by the ductus arteriosus (PGE1 or PGE2 keeps this open) Changes at Birth  on birth, the lungs inflate, pressure decreases on the right side of the heart, and the foramen ovale swings shut  postpartum, the ductus arteriosus constricts and becomes fibrotic  pulmonary vascular resistance decreases due to stretch of lungs, loss of hypoxia induced vasoconstriction and gradual thinning of pulmonary vessels Foetal Circulation Congenital Heart Defects (CHD)  Mild defects of septum, stenosis asymptomatic, may become apparent in adulthood  Moderate to large CHDs (in around 1/3rd) prone to develop dyspnea with exertion, exercise intolerance (easy fatigability), poor feeding, slow growth, congestive heart failure, cyanosis, endocarditis, arrhythmia, reduced peripheral perfusion, pulmonary congestion, tachycardia and recurrent lower respiratory tract infections depending on the type of defect – require early intervention CHD - Etiology o Multifactorial influence is said to be the cause in majority of cases o Currently, about 20% of CHD cases can be attributed to known causes such as genetic syndromes and teratogens. o Many appear to have a genetic basis – (e.g., trisomy) o Environmental factors associated with increased risk of CHD include -teratogens – such as alcohol ingestion, certain drugs, maternal rubella infection in the first trimester, maternal radiation, maternal diabetes, maternal age > 40 Classification of CHDs Cyanosis  Cyanosis refers to a blue-purple discoloration of the skin and mucous membranes caused by an elevated arterial blood concentration of deoxygenated hemoglobin (> 4 g/dL) Blood oxygenation is compromised in some CHDs, producing cyanosis (blue tinge to nails, lips, oral mucosa) CHD commonly divided as cyanotic or acyanotic Congenital Heart Defects Right to left shunt Obstructions – abnormal narrowing's in vessel or valves Cardiac Shunts – abnormal path of blood flow through heart or great vessels; could be right to left or left to right Obstructions  restricted openings or narrowing's on great vessels (coarctation of the aorta)  atresia or stenosis of valves: valves poorly formed or do not form and path may be completely blocked or reduce blood flow  workload is greatly increased to heart chamber proximal to the obstruction and heart failure may occur Shunt - Left-to-right shunt  oxygenated blood to flow back to the right side of the heart, to be sent to the lungs again. oxygenation of the systemic blood isn’t compromised initially (acyanotic defect)  left to right shunt increases pulmonary blood flow – left untreated large shunt causes Eisenmenger’s syndrome  right ventricle workload enhanced - RV hypertrophy - high right-heart pressure, may progress to a right-toleft shunt and cyanosis at advanced stages Shunt - Right-to-left shunt allow deoxygenated blood to flow from the right side of the heart into the left side of the heart and the systemic circulation, causing cyanosis Mixing of deoxygenated blood with oxygenated blood Murmurs  Hemodynamic and/or structural changes in congenital heart disease often produce turbulent flow and produce an audible noise – murmur – assist in the diagnosis of CHDs Medical Physiology - Guyton Classification of Congenital Heart Defects Acyanotic and Cyanotic Defects  atrial and ventricular septal defects  patent ductus arteriosus  congenital pulmonary valve stenosis & aortic valve stenosis Left to right shunt in early stages ≈ 40% incidence Acyanotic Obstructive lesions ≈ 25% incidence  coarctation of the aorta  tetralogy of Fallot  dextro-transposition of the great arteries Have right to left shunts or mixing  persistent truncus arteriosus ≈ 20% incidence Cyanotic lesions Atrial Septal Defect  Occur 1 in 1,500 live births  Persistent opening in the interatrial septum after birth, blood can shunt from the left atrium to the right atrium (high to low pressure)  Size of the defect determines the degree of shunting  Most infants asymptomatic (may have dyspnea on exertion, fatigue and recurrent lower respiratory tract infections) Atrial Septal Defect o systolic murmur (due to increased blood flow across pulmonary valve) on routine physical examination o volume overload causes enlargement of right atrium (RA) and right ventricle (RV) (diagnostic - on chest radiography, Echocardiography)  may lead to pulmonary hypertension (Eisenmenger’s syndrome), RV hypertrophy & RV high pressure - right-to-left shunt (cyanosis) and heart failure  large atrial septal defects are repaired by surgery or via transcatheter closure prior to the development of pulmonary complications Ventricular Septal Defect (VSD)  Most common (1.5 to 3.5 per 1,000 live births) and often associated with atrial septal defect, tetralogy of Fallot, & transposition of the great arteries  Small VSD asymptomatic (may close spontaneously by age 2)  Hemodynamic changes similar to atrial septal defect - shunt is at first from left-to-right, increasing right heart workload Figure 18-27, Copstead and Banasik, 3E  Large shunt causes volume overload in the right ventricle, pulmonary circulation, left atrium, and left ventricle Ventricular Septal Defect  moderate to large defects have physical Initial stage finding - systolic thrill and holosystolic murmur, and most likely to develop early right-sided heart failure  may lead to pulmonary hypertension, RV hypertrophy and shift to right-to-left shunt (and develop cyanosis)  surgical repair of large defects prior to pulmonary hypertension is appropriate Over time Patent Ductus Arteriosus  in utero, ductus arteriosus allows blood to bypass the lungs by flowing from the pulmonary artery to the aorta; normally closes shortly after birth  if persists (1 in 2,500 to 5,000) leads to patent ductus arteriosus – left to right shunt – may have no clinical manifestation if shunt is less and remains left-to-right – large shunt may lead to left ventricle failure or pulmonary hypertension Patent Ductus Arteriosus  harsh, grinding systolic murmur and continuous murmur throughout diastole  if severe, without surgical correction, left heart failure (symptoms such as tachycardia, fatigue, dyspnea, slow growth) may ensue or pulmonary hypertension may cause right-to-left shunt may develop If PDA is large shunt – LA enlarges, LV hypertrophies  commonly referred for closure- could be achieved with prostaglandin synthesis inhibitors or ligation via trans-catheter techniques or via surgical repair Congenital Pulmonary Valve Stenosis o obstruction to right ventricular outflow (congenitally fused pulmonic valve cusps) - constitutes 7.5% to 9.0% of all CHDs o severity depends on degree of stenosis and if other congenital defects are also present o in severe anomaly, dyspnea on exertion, systolic ejection murmur o afterload is increased and right ventricle pressure rises - hypertrophies eventually right heart failure o corrected by transcatheter balloon pulmonary valvuloplasty Congenital Aortic Valve Stenosis  narrowed aortic outflow (5 of 10,000 live births, high in males) – mostly bicuspid leaflet  may be asymptomatic in infants if mild but may progress and become symptomatic in adults  high LV afterload - LV hypertrophy – LV failure  prominent systolic murmur  corrected by transcatheter balloon valvuloplasty or surgical replacement of the stenosed valve if severe Coarctation of the Aorta  coarctation (narrowing) may occur (1 in 6,000) anywhere along the aorta but is commonly Reduced blood flow to lower body next to the ductus arteriosus (juxta ductal) frequently associated with other anomalies (often in Turner’s syndrome) more often in males than females Pathophysiology of Heart Disease (LS Lilly), 6th Edition, p392  the resistance offered by severe coarctation increases LV workload (high afterload), cause leading to aortic rupture or congestive heart failure early in neonatal life, exhibit differential cyanosis, severe acidosis, and leads to rapid death without treatment Coarctation of the Aorta  upper extremities have high BP which may cause intracranial hemorrhage; lower extremities have low BP  femoral, popliteal, and dorsalis pedis pulsations are weak or delayed compared with the bounding pulses of the arms and carotid vessels  mid-systolic ejection murmur  treatment involves surgery or balloon angioplasty Cyanotic Defects Tetralogy of Fallot Four heart defects present at birth  most common form of cyanotic CHD (5 in 10,000 live births) after infancy  severity relates to degree of pulmonary stenosis  determines RV pressure  which determines how much deoxygenated blood shunts to the LV Figure 18-30, Copstead and Banasik, 3E Tetralogy of Fallot o acute changes in systemic and pulmonary vascular resistances can affect direction of shunt (increases during exertion) o harsh systolic ejection murmur o the overriding aorta receives the deoxygenated blood, producing cyanosis  increased risk of infectious endocarditis o infants with severe pulmonary stenosis may present with profound cyanosis in the first few days of life.  early repair is advocated closure of VSD & RV outflow obstruction relief by surgery Transposition of the Great Arteries  Affects 40 out of 100,000 live births  Cyanosis in neonatal period; extremely hypoxic  Separate pulmonary and systemic circulation - parallel Transposition of the Great Arteries  infants who survive always have a patent ductus arteriosus and almost always have an atrial septal defect or ventricular septal defect, allowing some oxygenated blood into the systemic circulation Treatment: o medical emergency - maintain ductus arteriosus & create interatrial communication o corrective surgery - attach the arteries to the correct ventricles (Jatene procedure), Persistent Truncus Arteriosus  pulmonary artery and aorta have a single origin – admixture of oxygenated and deoxygenated blood  occurs in less than one out of every 10,000 live births Persistent Truncus Arteriosus  abnormally high blood flow to the lungs causes pulmonary hypertension, which: shunts more deoxygenated blood from the pulmonary artery (high pressure) to the aorta (low pressure) producing cyanosis leads to congestive heart failure (develops in the first week or two of life)  surgical correction required for survival Summary o congenital defects may be shunts or obstructions o shunts may be left-to-right (less serious) or right-to-left (more serious) o disorders classified according to whether cyanosis is present o acyanotic congenital defects are less serious than cyanotic congenital defects MD2011 – CVM – Week 11 CVM - Guided Learning Session Congenital Heart Defects Case 1 ML, a 14-year old girl, visited the doctor with symptoms including fatigue, decreased urination, and marked mood swings, irritability, and restlessness. Her mother indicates that ML used to be a very active child, but now she just wants to lie around reading. ML complains that her fingers are often cold and pale and she can’t seem to get warm. The doctor explains to them that ML is showing symptoms of heart failure and ultrasound examination shows that she has a ventricular septal defect. ML and her mother are shocked to learn about this heart defect only now. Questions 1 – 6 are related to Miss ML. Question 1 Explain to ML and her mother what a ventricular septal defect (VSD) is, and describe in particular the direction of blood flow through the VSD. A ventricular septal defect is a hole in the wall between the sides of your heart. Normally, you have a right side that pumps into the lungs, and a left side which pumps into the body. Since there is a hole, your left side is pumping into the right side. This caused the right side to have to work harder, and your right side is normally weaker because it only has blood through the lungs, now that the right side became overflowed for 14 years, the right side is now beginning to fail. Question 2 How could ML’s VSD trigger symptoms of heart failure? The right side of your heart is normally very weak because it only needs to pump blood in through the lungs. It became overflowed with blood from the left side of the heart subsequently making it need to work much harder. You're right ventricle has now begun to fail, because it cannot keep up with how much blood is being pumped into it Question 3 Explain to Miss ML and her mother why this condition could have remained undiagnosed for so long. This condition has remained unnoticed for so long because your right ventricle has adapted. It gets bigger and stronger every time it gets a little bit overflowed. But this can only happen so much. 1 MD2011 – CVM – Week 11 Question 4 Despite being described as pale and cold, why aren’t Miss ML’s fingers blue (cyanosed)? Your fingers and toes and mouth do not show cyanosis. This is because your right ventricle is failing instead of hyper adapting. Right ventricle overflows and gets stronger, there is potential to become so strong that it will overpower the left side of your heart. This will mean that some blood skips the lungs and goes straight into your circulation. This means that there would be an increasingly large amount of blood skipping the lungs and causing everything to be blue because it is oxygenated. Question 5 If the oxyggen saturation of Miss ML’s right atrial and right ventricular blood is measured through cardiac catheterization, would you find any difference? Explain this. The right ventricle will be more oxygenated due to the addition of blood from the left ventricle through the ventricular septal defect Question 6 If ML’s condition worsens, she will begin to show signs of cyanosis. What will have changed in her condition to lead to the cyanosis? More and more blood will skip the lungs, and this ventricular septic defect will switch from being a left to right shunt to a right to left shunt and will become much more dangerous Case 2 Mrs T, a 30-year old pregnant woman, brings her son to see the doctor. The child, KT, is 2-years old and seems a bit listless and tires easily. On physical examination, the doctor notices that muscle development in KT’s legs appears reduced compared to the development in the upper body, but it’s just an impression. Pulse examination reveals weak femoral pulse compared to the carotid pulse. Systolic pressure measured in KT’s right arm found to be 20 mmHg greater than in his leg. After extensive testing, it is discovered that this child has a coarctation of the aorta. Questions 7 – 10 are related to KT. Question 7 Describe coarctation of the aorta. If KT also has a patent ductus arteriosus, what kind of shunt would you expect? Coarctation of the aorta is when the aorta gets pinched and constricted by the ductus arteriosus. If your ductus arteriosus is still open, PDA, then it may be providing the lower extremities with some blood, or you could end up with aortic blood going into the right side of the heart. 2 MD2011 – CVM – Week 11 Question 8 Explain why KT might have reduced muscle development in his lower body compared to his upper body. You might have reduced muscle development in the lower extremities because they are constantly hypotensive and have less blood delivery to them Question 9 Provide a reason for why KT’s femoral pulse is weaker when compared to his carotid pulse. The femoral pulses weaker partly because the carotid pulse will be strong due to upper extremity hypertension, and also partly because there is so much less blood going down the thoracic and abdominal aorta Question 10 Why does KT have an arm-leg systolic blood pressure gradient, with systolic pressure being greater in his right arm than in his legs? Has an arm leg systolic blood pressure gradient because of the COA. There is less blood going to the legs Case 3 Ms. M is a 28-year-old woman who has just given birth to her first child. The baby weighed 2.1kg at birth and measured 40cm in length but emerged as a blue baby, indicating severe cyanosis. An ultrasound was promptly conducted, revealing that the baby has transposition of the great arteries (TGA). Questions 11 – 15 are related to Ms M’s baby. Question 11 Explain what TGA is and why this neonate is born blue. This neonate is born blue because the pulmonary artery and aorta have swapped positions. Or rather they have been transposed. This means that the left side of the heart receives blood from the lungs, and instead of pumping through the aorta to the body, they pump through the pulmonary artery back into the lungs. This means the body cannot get oxygenated blood, and the oxygenated blood cannot escape the lungs Question 12 The doctor informs Ms. M that they want to maintain the ductus arteriosus and enhance the size of the foramen ovale in the baby. What are these structures, and why does the doctor intend to keep them open? The duct arteriosus is a small vessel that links the aorta to the pulmonary artery. The foreman ovale is a hole in the atrial septum. Specifically a purposeful defect in the septum primum, with a one way valve on the septum secundum. Both of these structures allow to pass from the right side of the heart to be left side of the heart. In this case, this baby who has TGA, the foramen ovale and the ductus arteriosus are the only things supplying the baby with oxygenated blood to the peripheral tissues3 MD2011 – CVM – Week 11 Question 13 One method of maintaining the patency of the ductus arteriosus is to administer PGE1 to the baby. What is PGE1, and what is its role in fetal life and in the management of a baby with TGA? Additionally, mention other congenital heart defects in which PGE1 treatment might be beneficial. PGE1 is a prostaglandin and a vasodilator. It has a specific function in that when it drops that ductus arteriosus will close. This normally happens soon after birth naturally. When we administer it, this ductus arteriosus will remain open and even enlarge, allowing for greater blood flow to shunt between the right and left sides of the heart. Infusion of PGE1 will aid in any condition where the aorta is compromised, like COA Question 14 The doctor informs Ms. M that her baby will require surgery but it won’t be performed for at least two weeks. Based on what you know about Ms. M’s baby, what is the MOST LIKELY reason for the delay in surgery? the baby is small, and may not have finished developing??? Question 15 The Jatene procedure, or arterial switch, is an open-heart surgical intervention used to correct dextro-transposition of the great arteries. How does this surgical procedure bring the child’s heart and circulation back to normalcy? In the Jatene procedure, both the aorta and the pulmonary arteries are sliced just above the level of the coronary arteries, after the valves have been covered with caps to prevent more blood flow. The coronary arteries are then cut out of the base of the aorta. The aorta is then moved and sewn with the coronary arteries onto of the embryological pulmonary valve, which is attached to the left ventricle. The pulmonary artery, which was originally in the left ventricle, is attached to the former base of the aorta, which is attached to the right ventricle. Be careful with the right and left. Essentially, we swap everything. Case 4 An ambulance brings a 23-day-old baby boy to the emergency department. His parents report that over the past few days, he has had poor feeding and recurrent episodes of ‘turning blue’ associated with crying or feeding. Upon arrival, the baby appears agitated, with tachycardia, tachypneia, and profound cyanosis. He receives a diagnosis of Tetralogy of Fallot. Questions 16 – 20 are related to Case 4 4 MD2011 – CVM – Week 11 Question 16 What defects are present in the heart of a child born with Tetralogy of Fallot? There are four defects: a ventricular septal defect, hypertrophy of the right ventricle, an overriding aorta taking blood from both ventricles, and pulmonic stenosis. Question 17 Among the listed defects above, if present in a severe form, which one is likely to cause early symptoms? The one that causes early symptoms will be the ventricular septal defect, depending on activity of the baby. This can be a left to right shunt or a right to left shunt. Question 18 Why is systemic hypoxemia common in Tetrology of Fallot? This is extremely common because the overriding aorta can take blood from both ventricles, leading to a right to left shunt with some blood skipping the lungs. Question 19 What is the most likely reason for the cyanosis associated with crying or feeding? When feeding and or crying the baby would experience less ventilation leading to worsening cyanosis Question 20 Which cardiac murmur would you expect to hear in Tetralogy of Fallot? What causes the murmur in this congenital heart defect? I would expect to hear a systolic murmur and thrill. 5 MD2011 Cardiovascular Medicine Pathophysiology of Congenital Heart Defects Synthesis Session Anu [email protected] Eisenmenger Syndrome Chronic left-to-right shunting through a congenital cardiac defect leads to progressive morphological changes in the pulmonary vasculature  Reduction in pulmonary arteriolar lumen – progressive increase in resistance - Hyperviscosity (Rise in RBC) - Exertional dyspnea - Fatigue - Headaches Media hypertrophy, - Stroke proliferation of intima - fibrosis - Haemoptysis - Right to left shunt - Cyanosis - Rarely right heart failure  Could develop in atrial septal defects, ventricular septal defect, patent ductus arteriosus, persistent truncus arteriosus and transposition of great arteries - prevented by early detection and correction Individuals with Eisenmenger Syndrome o Avoid activities that enhance pulmonary vascular resistance (strenuous activities, high altitudes, pregnancy) o Symptomatic relief by pulmonary vasodilator therapy & phlebotomy for patients with symptomatic erythrocytosis o Effective long-term strategy for severely affected Eisenmenger syndrome - ventricular septal defect in a 31-year-old pregnant woman - cyanosis patients is lung or heart–lung transplantation. o Advance in diagnostic techniques and early correction of severe congenital heart defects, Eisenmenger syndrome has become less common. Patent Ductus Arteriosus o Widened pulse pressure and bounding pulses in older infants o Harsh, grinding systolic murmur and continuous murmur throughout diastole o If severe, without correction, left heart failure occurs in majority or right-to- left shunt may occur (i.e. from Pulmonary artery into the aorta) due to the development of Eisenmenger’s syndrome Patent Ductus Arteriosus  Commonly referred for closure (with prostaglandin synthesis inhibitors or ligation via transcatheter techniques or via surgical repair) Case 1 – ML Ventricular Septal Defect (VSD) The hemodynamic changes that accompany VSDs depend on the size of the defect and the relative resistances of the pulmonary and systemic vasculatures; signs and symptoms vary from asymptomatic murmur to heart failure No significant shunt After birth low pulmonary resistance - shunt from left to right; RV, Pulmonary circulation, LA and LV overloaded Case 1 – ML-VSD  Moderate to large VSDs allow blood to flow from the left ventricle to the right ventricle and lead to increase in pressure and flow in the lung circulation; augmented pulmonary blood flow cause increase in pulmonary vascular resistance due to Eisenmenger's syndrome, high right ventricle pressure - reverse the shunt, leading to hypoxemia and cyanosis  With large VSD, right ventricle, pulmonary circulation, left atrium, left ventricle – volume overload – develop heart failure (mostly left heart failure and in few right heart failure) very early in life Case 1 – ML-Ventricular Septal Defect Why undiagnosed – shunt may have increased with growth, active and pubertal growth may have tipped the balance Pale, cold fingers –peripheral vasoconstriction No cyanosis – shunt still left to right or may be produced only during exertion - cyanosis If situation worsens – cyanosis at rest (heart failure or Eisenmenger’s Syndrome or) Case 1 – ML-Ventricular Septal Defect  Echocardiography is used to determine the size and position of the defect o Surgical closure of the defect - placement of a synthetic or autologous patch effectively to close the shunt across the ventricular septum  Right atrial blood will have greater oxygen saturation than in right ventricle o Surgical correction of the defect is recommended in the first few months of life for moderate to large sized VSDs Case 2 - KT case Coarctation of the aorta o If coarctation is severe, presents as neonatal collapse o Acidosis occurs in severe defect due to too low blood flow to the lower extremities (to kidneys) o If ductus arteriosus do not close – direction of shunting through the ductus, depends on the pressure difference between the Pulmonary artery and aorta - typically right to left shunt as low pressure in the narrowed region than in the pulmonary artery producing differential cyanosis * To prevent infant death due to severe defect, administer PGE1 Case 2 - KT case – Coarctation of aorta In older age group presentation, o unnoticed in KT case in neonatal life (may be mild to moderate) – narrowed region not grown o muscle underdeveloped due to reduced blood flow to lower region; fatigue easily Hypertension in upper extremities which may cause intracranial hemorrhage & lower extremities have low BP (reason for low systolic pressure in legs); pressure gradient across the coarctation > 20mmHg (diagnostic feature) Weak delayed femoral pulses – reduced transmission of pressure wave along the coarctation region Case 2 - KT case – Coarctation of aorta  In uncorrected mild to moderate coarctation of aorta, compensatory alterations develop (remain asymptomatic) (1) development of left ventricular hypertrophy (2) dilatation of collateral blood vessels from the intercostal arteries that bypass the coarctation and provide blood to the more distal descending aorta.  Collateral vessels enlarge and can erode the under surface of the ribs (produce rib notching – diagnostic feature)  Left untreated, result in left ventricular (LV) pressure overload – LV hypertrophy and LV dysfunction Case 2 - KT case – Coarctation of aorta Treatment involves surgery or balloon angioplasty Resection and end to end anastomosis Balloon angioplasty Suitable for older age group Case 3 – Baby with transposition of arteries  Cyanosis in the first 24 hours of life  TGA is a lethal condition create mixing between the two circulations, maintain patency of ductus arteriosus create an inter-atrial communication using a balloon catheter PGE1 and Patent ductus arteriosus PGE1 administration is done for some congenital heart disease to maintain patency of ductus arteriosus After birth, PGE1 is given to keep the ductus arteriosus open in cases of transposition of the great arteries, aiding in oxygenated and deoxygenated blood mixing. PGE1 also used to treat severe pulmonary stenosis, critical aortic stenosis, severe coarctation of aorta, Tetralogy of Fallot with severe pulmonary stenosis Case 3 – Baby with transposition of arteries Palliative shunt created - Rashkind atrial balloon septostomy Increase blood admixture between two sides of heart Case 3 – Baby with transposition of arteries Curative surgery: Arterial switch – Jatene procedure preferably performed in the first 2 to 3 weeks of life 1. Procedure: Left 2. Coronary arteries and right coronary connected to neoaorta artery removed (reimplantation of coronary arteries) 3. Aorta and Pulmonary artery divided 4. Aorta and pulmonary artery reconstructed Case 4 – Tetralogy of Fallot (ToF)  Magnitude of shunt flow across the VSD is primarily a function of the severity of the pulmonary stenosis, but acute changes in systemic and pulmonary vascular resistances can affect it.  Cyanosis occurs,  soon after birth if severe obstruction to pulmonary blood flow.  whenever resistance in the pulmonary circulation becomes greater than systemic circulation if moderate obstruction or if obstruction gets worse Hypercyanotic or “Tet spells” o Respiratory distress or dyspnea and cyanosis during exertion such as crying, feeding or defecating – may lead to limpness, convulsions, cerebrovascular accidents, may lose consciousness, or even death o Crying –increased pulmonary vascular resistance o Feeding – decreased systemic resistance (vasodilation of blood vessels in GI tract) Greater pulmonary vascular resistance compared to systemic circulation - during spells Increased desaturated blood flow to the aorta – cyanosis Right to left shunt Methods for immediate relief from “Tet spells” o Hold baby in knee- chest position or squatting position - increases systemic resistance relative to pulmonary vascular resistance - reduces cyanosis o Toddlers or older children with Tetralogy of Fallot instinctively squat when they are short of breath – Fallot’s sign o Relief of hypoxia with O2 and morphine, intravenous propranolol reverses the cyanosis. Tetralogy of Fallot - Correction Shunt between branch of aorta and pulmonary artery Temporary shunt operation Palliative if severe: Modified Blalock-Taussig shunt- Artificial tube between Curative: Closure of the VSD and enlargement pulmonary artery and ipsilateral subclavian artery of the sub-pulmonary infundibulum “Something the Lord Made” film about the first attempts to surgically repair the Tetralogy of Fallot Image Source: www.hbo.com Alfred Blalock and Vivien Thomas Blue Baby Exhibition: www.medicalarchives.jhmi.edu/page1.htm Congenital Heart Defects Child with Congenital Heart Defects most often develop following  Poor feeding, failure to thrive, slow growth, slow weight gain  Susceptible for infective endocarditis, arrhythmias and frequent lower respiratory tract infections  Cyanosis or cyanosis with exertion (as during Tet spells), diaphoretic  If heart failure develops - present with fatigue, irritability, dyspnea, palpitations, exercise intolerance (in adults) and syncope in child having severe defect or develop later in adolescence or in adult life. Congenital Heart Defects Physical examination includes:  Auscultation, palpation, pulse examination  Chronic hypoxemia caused by the right-to-left shunt commonly results in clubbing of the fingers and toes Diagnosis:  Chest radiographs, ECG recording, Echocardiography, Cardiac catheterization , MRI, CT scan, pulse oximetry Treatment:  Pharmacological therapy (such as PGE1)  Surgical correction  Less-invasive catheter-based treatments Not for test purpose Cardiac Murmurs  The cause of murmur can be differentiated from their timing within the cardiac cycle.  Murmurs occur during systole, during diastole or during both systole & diastole  Helps the clinician narrow differential diagnosis Systolic Murmurs Atrial septal defect Ventral septal defect Pulmonary Stenosis Aortic Stenosis Tetralogy of Fallot Mid Systolic Coarctation of Aorta Systole and Diastole (or throughout cardiac cycle) Patent Ductus Arteriosus Murmurs