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Congenital Heart Defects Functional Overview Dr. Yasser Salem Objectives • • • • • Obstructive lesions right or left Mixing lesions Shunt lesions left to right or right to left Univentricular physiology Miscellaneous – Anomalies of coronary arteries – Vascular ring Obstructive cardiac lesions Cyanotic Acyanotic Obstructive cardiac lesions • low OXYGEN Enough blood, just not enough oxygen in the blood COMPLEX CARDIAC LESIONS = MIXING LESIONS • low BLOOD Enough oxygen, just not enough blood flow OBSTRUCTIVE CARDIAC LESIONS • COMBINATION Left sided obstructive lesions Left sided obstructive lesions Increased flow Backward effects Pulmonary venous congestion Increase RV afterload RV hypertrophy and failure Systemic venous congestion Forward effects Decrease peripheral tissue perfusion Decrease coronary perfusion Myocardial ischemia Left sided obstructive lesion • Aortic stenosis – Subvalvular (SAM, Pompe) – Valvular congenital stenosis – Supravalvular (Aortic coarc., hypoplastic arch) • Mitral stenosis – Subvalvular (Shone’s) – Valvular congenital stenosis – Supravalvular (core triatriatum) Shone’s anomaly Core triatriatum Left sided obstructive lesion • Hypoplastic left heart syndrome (HLHS) • Tricuspid atresia with transposed great arteries • Double-inlet left ventricle • IAA • DORV (some variations) Right sided obstructive lesions Right sided obstructive lesions Backward effects Pulmonary venous congestion Increase RV afterload RV hypertrophy and failure Systemic venous congestion Forward effects Decrease peripheral tissue perfusion Decrease coronary perfusion Myocardial ischemia Decrease pulmonary perfusion (lung oligemia) CYANOSIS Right sided obstructive lesions • • • • Tricuspid atresia Pulmonary atresia with IVS TOF with pulmonary atresia Severe Ebstein’s anomaly of the tricuspid valve • Critical PS • DORV (some variations) Right Left sided obstructive lesion • Aortic stenosis Pulmonary stenosis –Subvalvular (SAM, Pompe) –Valvular congenital stenosis –Supravalvular (Aortic coarc., hypoplastic arch) Tricuspid stenosis • Mitral stenosis –Subvalvular (Shone’s) –Valvular congenital stenosis –Supravalvular (core triatriatum) Right sided obstructive lesion • Pulmonary stenosis – Subvalvular (Fallot’s tetralogy) – Valvular congenital stenosis or atresia – Supravalvular (hypoplastic pulmonary arteries) • Tricuspid stenosis – Subvalvular (DCRV, Ebestien) – Valvular congenital stenosis – Supravalvular (eustachian valve) Eustachian valve Double Chamber Right Ventricle (DCRV) Mixing lesions • Defects with mixing of oxygenated and deoxygenated blood • Partial desaturation lead to compensatory in red cell mass and increase 2,3 DPG with increase in blood viscosity. Left sided obstructive lesions • Hypoplastic left heart syndrome (HLHS) • Tricuspid atresia with transposed great arteries • Double-inlet left ventricle • IAA • DORV (some variations) Left sided obstructive lesions • Complete mixing of systemic and pulmonary venous return • Ventricular outflow directed primarily to the PA • Systemic blood flow (Qs) – Largely by right-to-left ductal shunting – Dependent on the relative PVR and SVR • Systemic outflow obstruction is poorly tolerated • Usually accompanied by signs or symptoms of shock Left sided obstructive lesions • • • • • Maintain preload at maximum Maintain afterload at maximum Maintain contractility in neonates at maximum Maintain below maximum contractility in older patients Relative bradycardia is preferred not in neonates Quick guide to pediatric cardiopulmonary care, edwards Right sided obstructive lesions Right sided obstructive lesions • • • • Tricuspid atresia Pulmonary atresia with IVS TOF with pulmonary atresia Severe Ebstein’s anomaly of the tricuspid valve • Critical PS • DORV (some variations) Right sided obstructive lesions • Complete mixing of systemic and pulmonary venous return • Ventricular outflow predominantly directed out the aorta • Low pulmonary blood flow (Qp) in singleventricle patients implies an obligate right-to-left shunt (generally atrial level) • Clinical consequences of low Qp are variable Mixing lesions • Qp/Qs dependent upon PVR SVR balance • Hypoxemia and its consequences Adjust PVR SVR balance to gain optimal oxygen delivery Obstructive lesions • • • • • • • • • Qs decreased Low CO Hypotension Coronary perfusion decreased • LV failure Qp decreased Hypoxemia RV hypertrophy RV dysfunction TR • Avoid increase PVR • Hyperoxia • Hypoventilation Avoid SVR decrease Maintain preload Maintain PDA patency • Avoid decrease PVR • Relative hypoxia • Relative hypercarbia Objectives • • • • • Obstructive lesions right or left Mixing lesions Shunt lesions left to right or right to left Univentricular physiology Miscellaneous – Anomalies of coronary arteries – Vascular ring Shunt lesions • Shunts may intracardiac or extracardiac • Large shunts are non restrictive with low pressure gradient across • Small shunts are restrictive with high pressure gradient across Left to right shunt Factors affecting shunt flow Ventricular or Great artery level Atrial level Relative compliance Size of defect Right vs Left ventricle Pressure gradient between chambers or arteries Ratio of Blood viscosity PVR to SVR Left to right shunt Pathology of shunt flow Atrial or ventricular shunts Great artery shunts All shunts ↑RV filling ↑Pulmonary blood flow ↑RVEDV and ↑RVEDP Pulmonary edema RV failure ↑LA and LV blood flow ↓Diastolic BP ↑LVEDV and ↑LVEDP ↓Coronary perfusion pressure LV failure Myocardial ischemia ↑PVR Pulmonary hypertension Shunt reversal RV hypertrophy Pressure RV > LV Eisenmenger’s syndrome Left to right shunt Pathology of shunt flow • • • • Avoid decrease increase ininpulmonary PVR flow Enhance Avoid decrease the useinofsystemic vasoconstrictors flow Avoid extensive diastolic hypotension Avoid increase in total blood volume Pulmonary artery banding Pulmonary artery banding • Good banding – High pressure gradient across band by echo – Non-congested lung fields Objectives • • • • • Obstructive lesions right or left Mixing lesions Shunt lesions left to right or right to left Univentricular physiology Miscellaneous – TGA – Anomalies of coronary arteries – Vascular ring Transposition of great arteries • Mixing is mandatory for life • Left ventricle mass and function • Coronary anatomy Coronary Anomalies ALCAPA Vascular ring Vascular ring A I R Determinants of cardiac output preload Afterload Heart rate CNTRACTILITY CARDIAC OUTPUT OXYGEN DELIVERY Arterial O2 content OXYGEN extraction Venous saturation Angels Demons • Septal aneurysm • Atralization of the RV • Persistent left SVC • Parachute mitral valve • Interrupted IVC • Interrupted aortic arch • Restrictive VSD • Non-restrictive VSD • High pressure gradient across VSD • Law pressure gradient across VSD • Law pressure gradient across left or right obstructive lesions • High pressure gradient across left or right obstructive lesions