L6. Congenital Heart Diseases PDF

06 Clinical Sciences Dr. Amer Chaikhouni Congenital Heart Diseases 15th January 2020 Basant Moustafa Elsayed Nosaiba Yakti This document resorted to: 1. “Congenital Heart Diseases” Lecture Slides. 2. “Pathophysiology of Heart Diseases 6th” chapter 16 Overview: This sheet will cover the clinical aspe...

06 Clinical Sciences Dr. Amer Chaikhouni Congenital Heart Diseases 15th January 2020 Basant Moustafa Elsayed Nosaiba Yakti This document resorted to: 1. “Congenital Heart Diseases” Lecture Slides. 2. “Pathophysiology of Heart Diseases 6th” chapter 16 Overview: This sheet will cover the clinical aspects of patients with congenital heart diseases. First, we will talk about CHD in general (definition, epidemiology, causes, general pathophysiology, classification signs & symptoms, diagnosis and management). Then, will discuss each type in detail. Congenital heart diseases: Definition: Con (=join) genital (=genesis or development or embryological formation), so CHD are diseases of the heart that come in conjunction with the development of the heart during the embryonic period. Development of the heart: The heart basically is a pump with two inlet valves: the tricuspid and the mitral, two outlet valves: the pulmonary and the aortic valves, two pistons that pump the blood (ventricles) and two reservoirs (atria). The embryonic development of the heart is very complex and early, by week six of gestation, the heart basic structures are completed and at day 21 of gestation the heart starts beating. Figure 1 summarizes the heart development. Epidemiology: Even though the development of the heart is very complex, the congenital heart diseases’ incidence is very rare. The incidence of CHD in different studies varies from about 4/1,000 to 50/1,000 live births, it also varies based on what CHD are we looking at. CHD is approximately 60 times more prevalent than childhood cancer “with both being rare”. Figure 2 covers most of congenital heart diseases that vary in their incidence with ventricle septal defect (VSD) being the most common followed by atrial septal defect (ASD) then patent ductus arteriosus (PDA). Figure 1 Figure 2 CHD general pathophysiology: To know the underlying pathophysiology of the CHD, we can think about the normal embryological stages of development of the heart and predict what would happen if something went wrong during those stages. 1 For example: 1) The developmental stage: septation, which is the process of formation of septum that separate one tube into two, involving the rotation of that tube in two planes resulting in septation vertically and valve formation transversely. The problem: - Malformation of the septum that results in an incomplete separation of the one tube into two causing a communication between the left and the right chambers. For example, the common atria may fail to separate into right and left atrium resulting in Atrial Septal Defect, the same may happen in the ventricles causing Ventricle Septal Defect. 2) The developmental stage: the formation of the valves by the septation of the upper and lower champers. The problem: - Malformation of the inlet valves such as; tricuspid atresia, that happens when the valve doesn’t form or mitral stenosis which is the narrowing of the mitral valve. - Malformation of the outlet valves such as, pulmonary and aortic stenosis; the narrowing of the pulmonary trunk and the aorta respectively. 3) The developmental stage: the formation of aorticopulmonary septum that divides the truncus arteriosus into ascending aorta and pulmonary trunk. The Problem: - Persistent truncus arteriosus: failure of the formation of the aorticopulmonary septum. - Transposition of the great vessels: when the rotation (forming spiral septum) of the septum doesn’t occur, instead of the pulmonary trunk being anterior to the aorta, the opposite will happen and hence the aorta will arise from the RV while the pulmonary trunk from the LV. - Tetralogy of fallot: improper alignment of the aorticopulmonary septum resulting in 1) overriding aorta 2) pulmonary stenosis 3) VSD 4) RV hypertrophy. Now, you can easily understand the following classification of CHD: ▸ Septal Defects: atrial septal defect (ASD), ventricle septal defect (VSD), atrioventricular septal defect (AVSD). ▸ Obstruction: aortic stenosis (AS), pulmonary stenosis (PS), coarctation of aorta (COAO), mitral valve stenosis (MS/MV). ▸ Shunt: teratology of Fallot (TOF), Transposition of the Great Arteries (TGA), truncus arteriosus (TA), Total Anomalous Pulmonary Venous Connection (TAPVC) ▸ Hypoplasia (incomplete/ less development of one side of the heart): hypoplastic left heart syndrome (HLHS), hypoplastic right heart syndrome (HLRS). ▸ Conduction (problems of the conducting system of the heart that regulates the electrical impulses and the heart beats): heart block (HB), Wolff–Parkinson–White syndrome (WPW), Prolonged QT Syndrome. ▸ Complex → combination of the above. 2 Classification of CHD: If you suspect that a newborn has CHD, the following four basic questions should come to your mind to reach the correct diagnosis: Is the baby Cyanotic or Not Cyanotic? Cyanosis (described later in this sheet) is a clinical sign where the lips, ear lopes and the tips of the nose, fingers and toes look bluish in color. The bluish color that appear in cyanosis is a result of the increased concentration of the deoxygenated hemoglobin, hence decreased oxygen saturation. When both oxygenated and deoxygenated Hb mix at the capillary bed, the bluish color appear especially at the tongue, lips, ear lopes and the tips of the nose, fingers and toes because those areas have high vascularity and thin skin. Important notable clinical feature especially when the baby cries because the demand for oxygen increase and as a result the bluish color increases. Is this defect with Shunt or without?/ Is there a pathological murmur or not? This is detected using a stethoscope because any abnormal communication like ASD, VSD and PDA produce a sound. As the blood is flowing in a laminar smooth flow, no sounds are produced, we will only be able to listen to the valve closure sounds (heart sounds). However, if there is a narrowing or abnormal communication (shunt), the blood flow will be disturbed (turbulent blood flow) and we can hear murmurs. Auscultation is an important way of knowing whether a shunt is present or not because it is easy and clear to detect its producing sound (murmur) through the baby’s thin chest wall or even at the back. As the baby’s chest wall is so sensitive, the stethoscope and the physician ear is sensitive, and the room is quiet we can hear the normal blood flow in the heart, and this is known as functional murmur that is not due to pathologies. In most of the baby, this murmur is distinguished from the shunt murmur based on some features. For example, functional murmur is soft and not radiating while the shunt or obstruction murmur is harsh, loud and radiating to the neck and back. Also, the general health status of the baby may help in the differentiation, for example, a murmur associated with cyanosis is most likely a shunt murmur. With other Symptoms or not? As the baby cannot tell whether he has other symptoms or not or he feels unwell, there are some indirect ways of detecting those symptoms or ensuring his wellness. For example, the mother can be asked about her baby’s feeding, does the baby have breastfeeding or bottle-feeding? Does he feed continuously without interruption or he take breaks and start to huff and puff? Tachypnea, abnormal rapid breathing, is another symptom that can be noted. With Lung Congestion or Without? Lung congestion is the distention of blood vessels in the lungs and filling of the alveoli with blood which affect the gas exchange process. This happens when more blood is diverted to the lung because of a shunt or abnormal communication. So, we need to know whether the baby’s lungs are wet and over flooded with blood or they are dry and clean with no crepitation or wheezes. 3 Causes of CHD: ▸ Most of the time the cause of the CHD is Unknown and in most of the cases the CHD is not hereditary and doesn’t run in the families. ▸ Genetic defect: genes or chromosomes abnormalities may be associated with CHD. Most commonly, Down syndrome is associated with VSD, and Turner syndrome is associated with Coarctation of Aorta. Recall from Genes To Community everything becomes clear when it is too late :‘( Most congenital malformations occur when the mother is exposed to some problems early in the development of the embryo (first trimester). Problems such as: ▸ Smoking and Alcohol abuse. The main reasons how smoking and alcohol are correlated with CHD is not known. However, statistically they are associated. ▸ Infectious diseases: Rubella, Toxoplasmosis ▸ Drugs: Thalidomide (used to treat morning sickness), Hydantoin (used by epileptic mothers) Warfarin (an anticoagulant used for example in mothers had valve replacment that increase the likelihood of having baby with CHD by 5 or 7 folds. Therefore, following pregnant women who take warfarin is very important) ▸ Maternal illness: diabetes mellitus (DM), systemic lupus erythematosus (SLE) and obesity. ▸ Premature birth, Twins Symptoms of CHD: ▸ Cyanosis: low oxygen level in the blood cause the lips, fingers and toes to look blue. Cyanosis can be seen in tip of the nose, lips, tongue, ear lobes, tips and nails of fingers and toes. ▸ ▸ ▸ ▸ Tachypnea: abnormal rapid breathing, especially during feeding. Difficult Feedings Sweating (mainly during feeding). Growth Retardation: it happens because most of the energy will be diverted to support an adequate circulation, that is abnormal because of the CHD, causing energy loss and growth retardation. Growth retardation is an indication to interfere and fix the abnormal heart defect to allow baby to grow normally. 4 ▸ Clubbing: Definition: bulbous enlargement of the ends of one or more fingers or toes. Mechanism: Proliferation and edema of connective tissue result in loss of the normal angle between the skin and nail plate and excessive sponginess of the nail base. The underling mechanism is not well understood; however, the most likely ones are circulating vasodilator, tissue hypoxia, a neurocirculatory reflex, and genetic factors. Causes: unknown, but it is associated with severe hypoxia (cyanosis). Clubbing is seen in patients with CHD, but also it is associated with lung cancer, chronic pulmonary diseases such as; emphysema and asthma and gastrointestinal disorders like cirrhosis. Time: clubbing appears at later stages in babies with CHD, for example when the baby is 4 or 5 years old or even older. ▸ Asymptomatic because of the wide spectrum of the CHD. Signs of CHD: ▸ Tachycardia: fast heart beats because the heart needs to work beyond its capacity to compensate for the present defect and maintain adequate circulation. ▸ Heart Murmur. ▸ Other Abnormal Heart Sounds. ▸ Congested Lungs. ▸ Associated Anomalies. Diagnosis of CHD: ▸ Clinical examination: it gives you a clue of which CHD the patient may be having. ▸ Chest X-ray: it shows the lungs (clear/congested) and the heart shadow (normal/abnormal). ▸ Electrocardiogram: it detects the enlargement of ventricles or if they are dilated. ▸ Echocardiography: it shows the anatomy and function of the heart (the best to use if you need to choose only one test). ▸ Cardiac CT scan ▸ Cardiac MRI ▸ Cardiac catherization: - Measure the oxygenation in various champers and vessels. - Done by injecting a contrast and taking images to visualize the blood flow. - Can be done to fetus through the umbilical vessels. - The ultimate test to show the detailed anatomy of the heart. - Essential before any surgical correction of the defect to ensure the safety of the operation. 5 General notes about CHDs: ▸ They have a wide spectrum of presentation and severity. In other words, some defects may not be detected until the age of forty or sixty although they are present since birth. For example, a patient (more common in females) may be born with pulmonary stenosis and remains asymptomatic until later age. The reason is that PS was mild that the heart was able to accommodate for it. ▸ They undergo progressive changes. For example, in VSD and ASD the shunt may be reversed leading to cyanosis and Eisenmenger syndrome. ▸ Another congenital defects may be present along with CHDs as all systems are developed in the same embryonic period parallel to each other. Management of CHDs: ▸ Follow up. If the defect is mild (e.g.: small ASD), we will just wait and follow up the child. If he/she maintains a normal growth rate, then we will keep following. However, if the defect leads to growth retardation, we must correct it. ▸ Medications. For example; diuretics to manage the flooded lungs ▸ Cardiac catheterization intervention. It is used to close some defects (e.g.: ASD, VSD and PDA) with certain devices and without surgery. ▸ Surgical repair (if cardiac catheterization doesn’t work) ▸ Transplantation of the heart (in complex CHD) Types (classification depending on the presence of cyanosis): Congenital Heart Diseases Cyanotic "5Ts" Acyanotic With Shunt L to R Without Shunt With Shunt R to L Without Shunt Tertalogy Of Fallot Atrial Septal Defect Ventricular Septal Defect Coarcetation of the Aorta Truncus Arteriosus Aortic Stenosis Transposition of Great Vessels* Pulmonic Stenosis *it can also be classified as Cyanotic with shunt if associated with ASD, VSD and PDA. Patent Ductus Arteriosus 6 Acyanotic CHDs “with shunt” 1# Atrial Septal Defect (ASD) Pathophysiology Def Definition: an abnormal opening in the atrial septum. Epidemiology: relatively common, occurring with an incidence of 1 in 1,500 live births. Types: 1. True ASD: A true atrial septal defects is a persistent opening in the interatrial septum after birth that allows direct communication between the left and right atria. And based on where the opening in the atrial septum is, we will have: Ostium primum Ostium secundum Description When the opening appears in the When the opening is at the region of foramen ovale. inferior portion of the interatrial septum, adjacent to the AV valves. Causes Failure of the septum primum to ▸ Inadequate formation of the septum secundum. fuse with the endocardial cushions. ▸ Excessive resorption of the septum primum. ▸ Combination. Picture 2. Defects associate with ASD: Those are defects that are not a true ASD as they are morphologically distinct and not associated with absent of the anatomic atrial septum tissue “frequently the atrial septum itself is fully intact” and they have the same pathophysiology. They are: Sinus venosus defect Patent foramen ovale (PFO) The absence of normal tissue between When the foramen ovale failed to close after birth by the the right pulmonary vein(s) and the RA. fusion of the atrial septa. When the defect is large that results in Clinically silent, why? flow from the right pulmonary veins The valve of the foramen ovale (which is originally part of and left atrium into the right atrium, septum primum), though not sealed, remains closed the pathophysiology is similar to that since the LA pressure > RA pressure. of a true ASD. Complications - Cyanosis: When the RA pressure increases due to pulmonary hypertension or Right heart failure, a R to L shunt appear and that will divert the deoxygenated blood to the arterial circulation. Paradoxical embolism: When a thrombus in the systemic vein travel to the RA then passes through the PFO to the LA then to systemic atrial circulation causing systemic embolism (e.g.: stroke). 7 Pathophysiology: In the case of an uncomplicated ASD, oxygenated blood from LA is shunted into the RA, but not vice versa. This is due to two reasons: 1. In perinatal life, the pulmonary resistance is equal to the systemic resistance. Therefore, the shunting will be minimized. However, after birth, the pulmonary (R sided circulation) resistant will drop and become 10 folds less than the systemic resistance. Hence, especially after 3rd month of life, the shunting will increase as the blood prefers to move toward the less resistant pulmonary circulation (R side). 2. The RV becomes more compliant than does the LV, owing to the regression of right ventricular wall thickness and an increase in LV thickness, facilitating the left-toright directed shunt at the atrial level. Keep in mind that: the fact that Vena cava has higher pressure than pulmonary veins doesn’t determine the direction of shunt and it is still a L to R shunt. Also, the pressure in both atria is almost equal (5 mmHg). Overtime, overload on the RA & RV, enlargement of both, ↓RV compliance and the L to R shunt will lessen. As a result, if severe pulmonary vascular disease develops (RV and RA pressure), the direction of the shunt will reverse. ASD is generally acyanotic with L to R shunt, however in complicated ASD, R to L shunt may develop causing deoxygenated blood to enter the systemic circulation, resulting in hypoxemia and cyanosis. “in adults” Symptoms: Most infants with ASD are Asymptomatic. But if symptoms present, they could be: ▸ Dyspnea on exertion. ▸ Fatigue. ▸ Recurrent lower respiratory tract infections because the lung are over flooded with blood and a “wet lung” is perfect environment for infection to happen. ▸ Decreased stamina (fatigue) refers to one's inability to exert physical activity over a prolonged period of time, or across a certain amount of repeated activity. ▸ RA enlargement → atrial tachyarrhythmias → Palpitations. 8 Physical Examination: Blood traversing the ASD itself does not produce a murmur because of the absence of a significant pressure gradient between the atria, but the following can be appreciated: ▸ A RV heave → is a prominent systolic pulse that can be palpated along the lower-left sternal border. Reason: contraction of the dilated RV. ▸ A systolic murmur → present at upper-left sternal border. Reason: the increased volume of blood flowing across the pulmonary valve. ▸ A mid-diastolic murmur → present at the lower-left sternal border. Reason: the increased volume of blood flowing across the tricuspid valve. Diagnostic Studies On chest radiograph: ▸ The heart is usually enlarged because of RA and RV dilatation. ▸ The pulmonary artery is prominent with increased pulmonary vascular markings. Echocardiography with Doppler studies determines: ▸ Right atrial and right ventricular enlargement ▸ The location of the ASD and the presence of transatrial shunt. ▸ The direction and magnitude of the shunt ▸ An estimation of right ventricular systolic pressure. Cardiac catheterization: ▸ In a normal person, the oxygen saturation measured in RA is similar to that in the superior vena cava. However, an ASD with left-to-right shunting of welloxygenated blood causes the saturation in RA to be much greater than SVC. Treatment: Indications: if the volume of shunted blood is hemodynamically significant (even in the absence of symptoms). Types: ▸ Surgery: it could be direct suture closure or Pericardial or synthetic patch. ▸ Percutaneous ASD repair: it is done by using a closure device deployed by IV catheter “less invasive than surgery”. 9 2# Ventricle Septal Defect (VSD): Definition: an abnormal opening in the interventricular septum. Epidemiology: VSDs are the most common among the CHD, having an incidence of 1.5 to 3.5 per 1,000 live births. Pathophysiology: 1. The hemodynamic changes and magnitude of the shunt that accompany VSDs depend on: 1) The size of the defect: - In small VSDs, the defect itself offers more resistance to flow than the pulmonary or systemic vasculature, thereby preventing a significant quantity of left-to-right shunting. - Conversely, with larger “nonrestrictive” defects, the volume of the shunt is determined by the relative pulmonary and systemic vascular resistances. 2) The relative resistances of the pulmonary and systemic vasculatures: - In the perinatal period, the pulmonary vascular resistance approximates the systemic vascular resistance, and minimal shunting occurs between the two ventricles. - After birth, however, as the pulmonary vascular resistance falls, an increasing left-to-right shunt through the defect develops. 2. When this shunt is large, the RV, pulmonary circulation, left atrium, and LV experience a relative volume overload. - Initially, the increased blood return to the LV increases the stroke volume (via the Frank–Starling mechanism). - Over time, the increased volume load can result in progressive chamber dilatation, systolic dysfunction, and symptoms of heart failure. As in ASD, the pulmonary vascular resistance will eventually approach or exceed the systemic resistance. Therefore, the intracardiac shunt may reverse its direction (i.e., Eisenmenger syndrome), leading to systemic hypoxemia and cyanosis. Pulmonary and systemic vascular resistances Perinatal period Neonatal period Pulmonary resistance = systemic Pulmonary resistanca < systemic The shunting will be minimized The L to R shunt will increase causing: Hemodynamic changes and shunt magnitude Depends on Depends on Size of defect Small VSDs Overloaded of RV, pulmonary circulation, LA and LV Large VSDs More resistance to flow Nonrestrictive defect Decreases the L to R shunt Do not affect the volume of the shunt 1. Initially 2. Overtime The overlaod will be compensated by LV causing high stroke volume The compensation will decrease resulting in: Progressive chamber dilatation Systolic dysfunction Symptoms of heart failure 10 Types: Membranous Muscular ▸ Excessive diverticulation of the muscular septum perforations in the muscular IVS. Causes ▸ Failure of muscular IVS to fuse with the free edge of conus septum. ▸ Deficient development the proximal conus swelling. ▸ Failure of ECs fusion. Symptoms: The symptoms vary depending on the severity of the VSDs and the complications: Patients with Small VSD Remain symptoms free Complicated VSD Tachypnea Poor feeding Faliure to thrive Large VSD + pulmonary vascular disease and reversed shunts All pt regardless of the VSD size Bacterial endocarditis Dyspnea Cyanosis Frequent LRTI Physical Examination: The most common physical Finding are: 1) A harsh holosystolic murmur that is best heard at the left sternal border. Smaller defects → the loudest murmurs because of the great turbulence that they cause. 2) A systolic thrill can commonly be palpated over the region of the murmur. 3) A mid-diastolic rumbling murmur can often be heard at the apex owing to the increased flow across the mitral valve. Diagnostic Studies: On chest radiographs: ▸ Patients with small defects→ normal cardiac shape ▸ Patients with large shunts→ cardiomegaly and prominent pulmonary vascular markings are present. The ECG shows: ▸ LA enlargement and LV hypertrophy in those with a large shunt. ▸ RV hypertrophy if pulmonary vascular disease has developed. Echocardiography with Doppler studies determines: ▸ The location of the VSD ▸ The direction and magnitude of the shunt ▸ An estimation of right ventricular systolic pressure. Treatment: ▸ By age 2, at least 50% of small and moderate-sized VSDs undergo sufficient partial or complete spontaneous closure to make intervention unnecessary. ▸ Moderate-sized defects without pulmonary vascular disease but with significant left-toright shunting can be corrected later in childhood. ▸ Children with accompanying heart failure or pulmonary vascular hypertension will undergo surgical correction of the defect at first few months of life. 11 3# Patent Ductus Arteriosus (PDA): Definition: the failure of ductus arteriosus, a vessel that connects the pulmonary artery to the descending aorta during fetal life, to close after birth. Epidemiology: It has an overall incidence of about 1 in 2,500 to 5,000 live term births. Risk actors: 1st trimester maternal rubella infection, prematurity and birth at high altitude. Pathophysiology: PDA results in a persistent shunt between the descending aorta and the left pulmonary artery. The magnitude of flow through the shunt depends on: ▸ The cross-sectional area and length of the ductus itself ▸ The relative resistances of the systemic and pulmonary vasculatures “described earlier”. 1. Prenatally, when the pulmonary vascular resistance is high, blood is diverted away from the immature lungs to the aorta. 2. Postnatally, as the pulmonary resistance drops, the shunt reverses direction, and blood flows from the aorta into the pulmonary circulation instead. 3. The left-to-right shunt causes the pulmonary circulation, LA and LV become volume overloaded leading to LV dilatation and left-sided heart failure. 4. The right heart remains normal. However, if pulmonary vascular disease develops (pulmonary resistant > systemic resistant), the shunt will be reversed and blood will flow from the pulmonary artery, through the ductus, to the descending aorta. Clinically, when the shunt is reversed, the resulting flow of unsaturated blood to the lower extremities causes cyanosis of the feet (and eventually clubbing); the upper extremities are not cyanotic, because they receive normally saturated blood from the aorta proximal to the ductus (see next Figure). Symptoms: Patients with Small PDA Asymptomatic “Children” Moderate-sized PDA Dyspnea Fatigue Palpations “Adolescence and adult life” Large PDA Congestive heart failure Poor feeding Other symptoms Atrial fibrilation slow growth "Due to LA dialataion" Frequent LRTI Endarteritis Physical Examination: The most common finding in a patient with a left-to-right shunt through a PDA is: ▸ A continuous, machine-like murmur→ heard best at the left subclavicular region. Reason: a pressure gradient exists between the aorta and pulmonary artery in both systole and diastole that is why it is a continuous murmur. Diagnostic Studies” Chest radiograph shows: ▸ Enlarged cardiac silhouette (LA & LV enlargement) with prominent pulmonary vascular markings. The ECG shows: ▸ LA enlargement and LV hypertrophy when a large shunt is present. Echocardiography with Doppler imaging can: ▸ Visualize the defect and demonstrate the flow through it. ▸ Estimate right-sided systolic pressures. 12 Acyanotic CHDs “without shunt” 2# Aortic stenosis 3# Pulmonic stenosis Definition Abnormal structural development of the aortic Dynamic or fixed anatomic obstruction to flow valve leaflets (bicuspid leaflet structure instead of from the RV to the pulmonary arterial vasculature. the normal 3 leaflet configuration). Pathophysiology AS causes LV hypertrophy. Reason: the valvular PS causes RV hypertrophy. Reason: the impaired orifice is significantly narrowed. Therefore, the right ventricular outflow leads to increased RV left ventricular systolic pressure must increase to pressures and chamber hypertrophy. pump blood across the valve into the aorta. So, Untreated severe pulmonic stenosis typically results in right-sided heart failure. pressure load → LV hypertrophy. In addition, pulmonary artery dilation will be In addition, dilatation of the aorta will be developed. Reason: The high-velocity jet of blood developed. Reason: the high-velocity jet of blood against the wall of the pulmonary artery. that passes through the stenotic valve. Symptoms in Infants < 1year Tachycardia Poor feeding Tachypnea Failure to thrive Older children Mostly asymptomatic “If they develop symptoms, they will be like adults’ ” Symptoms in Adults Exertional dyspnea Mild PS Moderate PS Dyspnea with exertion Exercise intolerance Fatigue Angina pectoris Sever PS Tachycardia Asymptomatic Syncope “Symptoms of heart failure” Pedal edema Abdomnal fullness “Symptoms of R-sided heart failure” Physical examination ▸ RV heave is palpated over the sternum. ▸ A harsh crescendo–decrescendo systolic murmur, loudest at the base of the heart with ▸ A loud, late-peaking, crescendo–decrescendo systolic ejection murmur is heard at the upper radiation toward the neck. left sternal border, often associated with a Present from birth because it does not depend palpable thrill. on the postnatal ↓pulmonary vascular resistance. ▸ Widened splitting of the S2 with a soft P2 ▸ Reversed splitting of the S2 “paradoxical component is caused by the delayed closure of splitting” caused by the delayed closure of the stenotic pulmonary valve. aortic valve not the pulmonary valve. Diagnostic studies X-ray Enlarged LV and dilated ascending aorta. Enlarged RA and RV + pulmonary artery dilation. ECG left ventricular hypertrophy. RV hypertrophy with right axis deviation. ECHO Abnormal structure of the aortic valve + The pulmonary valve morphology + the degree the degree of LV hypertrophy of RV hypertrophy Treatment Mild stenosis usually does not progress or require treatment. In sever obstruction, dilation of the stenotic valve is required, and it is done by Transcatheter Balloon Valvuloplasty, if failed, surgery is needed. Balloon 13 3# Coarctation of Aorta (CoA): Definition: discrete narrowing of the aortic lumen. Types: Preductal (infantile) or postductal (adult-type) based on the location of the aortic narrowing in relation to the ductus arteriosus. These terms have been largely not used because no etiologic differences between both are substantiated. Hence, the vast majority of coarctations are actually juxtaductal (i.e., “next to” the ductus). Possible mechanism “why CoA is happening?”: 1) Blood flow through the left side of the heart and ascending aorta during fetal life leads to hypoplastic development of the aorta (“no flow, no grow”). 2) Ectopic muscular ductus arteriosus tissue extends into the aorta during fetal life and constricts following birth at the same time the ductus is caused to close. Pathophysiology: Narrowing of aorta causes high afterload on the LV. Therefore: - Branches of Aorta that are proximal to (before) the narrowing → supply head and upper limbs → high pressure. - Descending aorta is distal to (after) the narrowing → supply lower limbs → diminished pressure. If coarctation is not corrected, compensatory alterations include: - Development of left ventricular hypertrophy - Dilatation of collateral blood vessels from the intercostal arteries that bypass the coarctation and provide blood to the more distal descending aorta. Eventually, these collateral vessels enlarge and can erode the undersurface of the ribs (Fig. 3). Figure 3 Symptoms: This defect vary in severity that it may not appear in childhood but will be suspected in “hypertensive teens”. On the other hand, Patients with severe coarctation usually present very Figure 4a shortly after birth with symptoms of heart failure. So, the possible symptoms are: ▸ Differential cyanosis: CoA may be associated with PDA making it worse, and depending on the position of coarctation in relation to the PDA, the following two scenarios may happen: 1) Coarctation proximal to the PDA (Preductal): -The aorta before the narrowing will have high pressure, hence upper half of the body is perfused with well-oxygenated blood. - The pressure in the pulmonary artery will be higher than the aorta after the narrowing, hence right-to-left flow of poorly oxygenated blood will supply the lower half → cyanosis (Fig. 4a). 14 2) Coarctation distal to the PDA (Postductal): - The aortic arch before the narrowing will have high pressure compared to the pressure of the pulmonary artery (PA), hence the blood will flow rapidly through the PDA to the PA resulting in congested lungs (Fig. 4b). Physical Examination: 1) If the coarctation occurs distal to the takeoff of the left subclavian artery (Fig. 5a), the systolic pressure in the arms is greater than that in the legs. The femoral pulses are weak and Figure 4b delayed. “radio-femoral delay” A systolic pressure in the right arm that is 15 to 20 mm Hg greater than that in a leg is sufficient to suspect coarctation, because normally the systolic pressure in the legs is higher than that in the arms. 2) If the coarctation occurs proximal to the takeoff of the left subclavian artery (Fig. 5b), the systolic pressure in the right arm may exceed that in the left arm. Figure 5 Cyanotic CHD “with shunt” 1# Teratology of Fallot (ToF): Epidemiology: the most common form of cyanotic congenital heart disease after infancy. Cause: results from a single developmental defect: an abnormal anterior and cephalad displacement of the infundibular (outflow tract) portion of the interventricular septum. As a consequence, four anomalies arise that characterize this condition: Anomaly Cause VSD Anterior malalignment o the interventricular septum PS Subvalvular pulmonic stenosis because of obstruction from the displaced infundibular septum. Overriding aorta Receives blood from both ventricles RV hypertrophy The high-pressure load placed on the RV by the pulmonic stenosis. 15 Pathophysiology: Increased resistance by the subvalvular pulmonic stenosis causes deoxygenated blood returning from the systemic veins to be diverted from the RV, through the VSD to the LV, and into the systemic circulation, resulting in systemic hypoxemia and cyanosis. Symptoms: 1. Dyspnea on exertion. 2. Teratology spells: Definition: acute hypoxemic attacks represent a true emergency. Mechanism: Teratology spell occur when the right to left shunt increase due to: ▸ High obstruction to pulmonary flow so blood will be diverted through VSD. ▸ Decrease systemic resistance due to exercise or fever. ▸ After exertion, Feeding, or crying when systemic vasodilatation results in an increased right to- left shunt. Manifestation: irritability, cyanosis (because of high mixing through the VSD), hyperventilation, and occasionally syncope or convulsions. Management: Children learn to alleviate their symptoms by squatting down, why? - That is thought to increase systemic vascular resistance by “kinking” the femoral arteries, thereby decreasing the right-to-left shunt and directing more blood from the RV to the lungs. 3. Clubbing due to extreme hypoxia. Physical examination: ▸ A palpable heave → best heard along the left sternal border. Reason: RV hypertrophy. ▸ The S2 is single, composed of a normal aortic component, but the pulmonary component is inaudible. ▸ A harsh systolic ejection murmur → heard best at the upper left sternal border. Reason: the turbulent blood flow through the stenotic right ventricular outflow tract. There is usually no distinct murmur related to the VSD, because it is typically large and thus generates little turbulence. Diagnostic studies: Chest radiography demonstrates: - Prominence of the RV and decreased size of the main pulmonary artery segment, giving the appearance of a “boot-shaped” heart. - Clear lung (washed out lungs) because there is no congestion of lungs, due to pulmonic stenosis, it looks pale and contains little blood. 16 Cyanotic CHD “without shunt” 1# Transposition of Great Arteries (TGA): Definition: a defect cause each great vessel to inappropriately arise from the opposite ventricle; that is, the aorta originates from the RV and the pulmonary artery originates from the LV. Cause: mostly it is unknown, but one theory contends that failure of the aorticopulmonary septum to spiral in a normal fashion during fetal development is the underlying problem. Pathophysiology: TGA separates the pulmonary and systemic circulations by placing the two circuits in parallel rather than in series. This arrangement forces: - Desaturated blood from the systemic venous system → RV → systemic circulation through the aorta “without undergoing normal oxygenation in the lungs. - Oxygenated pulmonary venous return → LV → pulmonary artery → lungs “without imparting oxygen to the systemic circulation”. The result is an extremely hypoxic, cyanotic neonate. TGA is compatible with life in utero because the oxygenated blood passes through the foramen ovale and ductus arteriosus to the systemic circulation. After birth, normal physiologic closure of the ductus and the foramen ovale eliminates the shunt between the parallel circulations that results in death because oxygenated blood does not reach the systemic tissues. However, if the ductus arteriosus and foramen ovale remain patent (either naturally or with exogenous prostaglandins or surgical intervention), communication between the parallel circuits is maintained, and sufficiently oxygenated blood may be provided to the brain and other vital organs. Symptoms: Generalized cyanosis is apparent on the first day of life. Diagnostic studies: chest x-ray is usually normal, although the base of the heart may be narrow owing to the more anterior–posterior orientation of the aorta and pulmonary artery. 17 2# Truncus Arteriosus (TA): It is a rare type of CHD that results from the incomplete formation of the aorticopulmonary septum causing incomplete sepeartion of the aorta and the pulmonary artery. It consists of a single great artery arising from the cardiac ventricles through a single arterial valve which is most often placed over a large VSD. Symptoms: They include: Tachypnea, Failure to thrive, Cyanosis, Flooded lungs and Poor development “often associated with DiGeorge syndrome” Diagnosis: (1) ▸ A pansystolic murmur → best detected at the left sternal border. (2) ▸ S2 is single and loud. (4) Pulmonary a. Common arterial trunk. Common arterial valve. Eisenmenger syndrome: It is a condition of severe pulmonary vascular obstruction that results from chronic left-to-right shunting through a congenital cardiac defect (ASD, VSD, PDA, AVSD and truncus arteriosus). The elevated pulmonary vascular resistance causes reversal of the original shunt (to the right-to-left direction) and systemic cyanosis. Pathophysiology: 1. The lungs are over flooded with blood because of the left to right shunt. 2. By time, the Histology of pulmonary arterioles that are used to be thin and soft with large lumen, will change. 3. The pulmonary arteriolar media hypertrophies and the intima proliferates, reducing the cross-sectional area of the pulmonary vascular bed (↓lumen). 4. By time, the vessels become thrombosed, and the resistance of the pulmonary vasculature rises by 10 folds exceeding the systemic vasculature and the direction of shunt flow reverses (becomes R to L). Signs and Symptoms: ▸ Hypoxemia ▸ Exertional dyspnea and fatigue. ▸ Hyperviscosity symptoms: They are fatigue, headaches, and stroke. Reason: Reduced Hb saturation stimulates the bone marrow to produce more RBCs (erythrocytosis), ▸ Hemoptysis. Reason: Infarction or rupture of the pulmonary vessels. Treatment: The syndrome could be managed by avoidance of strenuous activities and use of pulmonary vasodilators therapy. However, the only effective long-term strategy or severely affected patients is lung or heart–lung transplantation. Of course, detection and early correction of CHD makes Eisenmenger syndrome less common. Don’t hesitate to contact Basant Elsayed / Nosaiba Yakti regarding any clarification, concern or suggestion! 18