Congenital Heart Disease Student Notes PDF

CONGENITAL HEART DISEASE NRAN 80413 SPRING 2024 RON ANDERSON, M.D. 1 OUTLINE TRANSITION FROM FETAL TO NEONATAL CIRCULATION ACYANOTIC LESIONS ASD VSD PATENT DUCTUS ARTERIOSUS AORTIC STENOSIS PULMONIC STENOSIS COARCTATION OF THE AORTA CYANOTIC LESIONS TETROLOGY OF FALLOT TRANSPOSITION OF THE GREAT ART...

CONGENITAL HEART DISEASE NRAN 80413 SPRING 2024 RON ANDERSON, M.D. 1 OUTLINE TRANSITION FROM FETAL TO NEONATAL CIRCULATION ACYANOTIC LESIONS ASD VSD PATENT DUCTUS ARTERIOSUS AORTIC STENOSIS PULMONIC STENOSIS COARCTATION OF THE AORTA CYANOTIC LESIONS TETROLOGY OF FALLOT TRANSPOSITION OF THE GREAT ARTERIES TRUNCUS ARTERIOSUS 2 THE FETAL CIRCULATION Ductus venosus Allows majority of oxygenated placental blood to bypass liver and enter IVC Foramen ovale Allows oxygenated blood from placenta to pass from RA to LA and into the systemic circulation Ductus arteriosus Deoxygenated blood from SVC passes into RV and pumped into PA where much of it travels via DA into descending aorta to placenta to be oxygenated 3 GUYTON TRANSITION FROM FETAL TO NEONATAL CIRCULATION Increased SVR – Loss of low pressure placental circulation Decreased PVR – Expansion of lungs – Vasodilation due to aeration Closure of foramen ovale – Due to flow reversal as SVR increases and PVR decreases Closure of ductus arteriosus – Flow reversal followed by constriction of the muscular wall Closure of ductus venosus – Due to muscular constriction of vessel wall 4 CONGENITAL HEART DISEASE Incidence 7-10 / 1000 live births Most common form of congenital disease Chromosomal abnormalities – 10% – Majority of these associated with Trisomy 21 Multifactorial origin – 90% – Genetic + external factors » Maternal diabetes » Rubella » ETOH abuse » Lithium use 5 INCIDENCE OF CONGENITAL HEART DISEASE DISEASE INCIDENCE (%) Ventricular septal defect 35 Atrial septal defect 9 Patent ductus arteriosus 8 Pulmonary stenosis 8 Aortic stenosis 6 Coarctation of the aorta 6 Atrioventricular septal defect 3 Tetralogy of Fallot 5 Transposition of the great arteries 4 ADAPTED FROM HINES 6 SHUNTING VERSUS OBSTRUCTIVE VERSUS “OTHER” LESIONS SHUNTING OBSTRUCTIVE OTHER ASD AORTIC STENOSIS TRANSPOSITION OF GREAT VESSELS VSD PULMONIC STENOSIS TRUNCUS ARTERIOSUS PDA AORTIC COARCTATION TAPVR TOF TOF HYPOPLASTIC LEFT HEART TRICUSPID ATRESIA DOUBLE AORTIC ARCH 7 Cardiac Conditions Associated With the Highest Risk of Adverse Outcome From Endocarditis – Prophylaxis is Reasonable Prosthetic cardiac valve or prosthetic material used for cardiac valve repair Previous IE Congenital Heart Disease (CHD) – Unrepaired cyanotic CHD, including palliative shunts and conduits – Completely repaired congenital heart defect with prosthetic material or device, whether placed by surgery or by catheter intervention, during the first six months after the procedure – Repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device (which inhibit endotheliazation) Cardiac transplant recipients who develop cardiac valvulopathy 8 2007 AHA Guideline Prevention of Infective Endocarditis ACYANOTIC LESIONS ASD VSD PATENT DUCTUS ARTERIOSUS AORTIC STENOSIS PULMONIC STENOSIS COARCTATION OF THE AORTA 9 ACYANOTIC DISEASE Left-to-Right shunt Results in: Increased pulmonary blood flow Pulmonary hypertension Right ventricular hypertrophy Heart failure Repair is best done at an early age Once PVR > 1/3 SVR corrective surgery may not produce significant benefit 10 11 ATRIAL SEPTAL DEFECT Typically result from spontaneous genetic mutations Small lesions may remain asymptomatic throughout life Threshhold for closure Pulmonary blood flow > 1.5 x systemic blood flow Procedure Percutaneous or open Symptoms of a large ASD HINES DOE Supraventricular dysrythmias Right heart failure Paradoxical air embolus Recurrent pulmonary infection ATRIAL SEPTAL DEFECT Systemic vs. Pulmonary Vascular Resistance Increase left-to-right shunt – Increased SVR – Decreased PVR Decrease left-to-right shunt – Decreased SVR – Increased PVR Systemic vs. Pulmonary Blood Flow Increased pulmonary blood flow – Possible dilution of IV drugs Decreased systemic blood flow – Possible delay in inhalational induction 12 13 VENTRICULAR SEPTAL DEFECT Most common congenital heart defect But often close spontaneously in infancy Percutaneous or open procedure Large VSD Initial Left-to-Right shunt Over time RVH occurs May become a Right-to-Left shunt Surgical correction HINES Prior to PVR reaching 0.7 SVR VENTRICULAR SEPTAL DEFECT Systemic vs. Pulmonary Vascular Resistance Left-to-right shunt (as described for ASD) – Volatile anesthetics and positive pressure ventilation may improve condition Late-stage cyanotic Right-to-Left shunt – Volatile anesthetics and positive pressure ventilation may worsen shunt – Increased FiO2 and sympathetic stimulation may reduce shunting However: – If right ventricular infundibular hypertrophy exists, sympathetic stimulation may increase right ventricular outflow obstruction and worsen a Right-to-Left shunt 14 15 PATENT DUCTUS ARTERIOSUS Failure of spontaneous closure Function of ductus arteriosus in fetus Allows PA blood to bypass lungs and travel to placenta via aorta Most children remain asymptomatic until adolescence, then develop: HINES Pulmonary hypertension Heart failure PATENT DUCTUS ARTERIOSUS Medical treatment Non-selective inhibition of prostaglandin synthesis – Indomethacin – Ibuprophen Procedure Neonate – Typically open, but off pump via left thoracotomy Adolescent, young adult – More commonly by interventional cardiology Anesthesia Minimize Left-to-Right shunt – Volatile anesthetics – Positive pressure ventilation Avoid – Increased SVR – Decreased PVR 16 AORTIC STENOSIS Bicuspid aortic valve in 2-3% of population Often associated with other CV abnormalities Severe stenosis may present as heart failure in infancy, however symptoms typically do not develop until adulthood Angina Syncope Heart failure HINES 17 PULMONIC STENOSIS Symptoms Initially – Dyspnea on exertion With development of right heart failure – Peripheral edema – Ascites If foramen ovale is patent – Cyanosis can develop due to Rightto-Left shunting Management Avoid decreases in systemic blood pressure Maintain sinus rhythm with a normal heart rate Changes in PVR not typically a problem HINES 18 COARCTATION OF THE AORTA Anatomic location Preductal – Just proximal to ductus arteriosus Postductal – Most common – Just distal to ductus arteriosus Signs and symptoms BP difference between upper and lower body Hypertension, CHF, aortic dissection Proximal to lesion – Headache, dizziness, epistaxis, palpitations Distal to lesion – Claudication in LEs 19 COARCTATION OF THE AORTA Treatment Resection or balloon dilation and stenting when pressure gradient reaches 30 mmHg Anesthetic Management Measure BP above and below lesion Cross-clamp concerns Post-operative concerns – Paradoxical HTN – Effects of decreased spinal cord blood flow during cross-clamp – Abdominal pain 20 CYANOTIC LESIONS TETRALOGY OF FALLOT TRICUSPID ATRESIA TRANSPOSITION OF THE GREAT ARTERIES TRUNCUS ARTERIOSUS TOTAL ANOMALOUS PULMONARY VENOUS RETURN HYPOPLASTIC LEFT HEART 21 CYANOTIC LESIONS Right to Left shunt Results in: – Decreased pulmonary blood flow – Arterial hypoxemia Risks – Thromboembolism 20 erythrocytosis due to hypoxemia – Brain abscess Survival Very limited in the absence of surgical correction Requires communication of the systemic and pulmonary circulations 22 23 TETRALOGY OF FALLOT Most common cyanotic congenital lesion Components Large, single VSD Overriding aorta Right ventricular outflow obstruction Right ventricular hypertrophy HINES PATHOPHYSIOLOGY OF TOF Large VSD results in equalization of left and right ventricular pressures, resulting in RVH Right-to-Left shunting occurs due to VSD, RVH, and obstruction to the right ventricular outflow tract (PA) Resulting decrease in pulmonary blood flow produces arterial hypoxemia Effects of change in SVR Decreased SVR increases R-to-L shunt, worsening hypoxemia Increased SVR reduces R-to-L shunt 24 TETRALOGY OF FALLOT Signs and Symptoms Systolic ejection murmur Cyanosis Increased hemoglobin and hematocrit Squatting Hypercyanotic attacks CVA Cerebral abscess Infective endocarditis 25 RIGHT-TO-LEFT SHUNT REDUCE SHUNT Increased SVR Ketamine Alpha agonism Decreased PVR Increased FiO2 Increased pulmonary blood flow Beta-blockade if outflow obstruction due to infundibular spasm WORSEN SHUNT Decreased SVR Volatile anesthetics Histamine release Alpha-blockade Increased PVR Positive pressure ventilation PEEP Opening the chest Increased contractility Increases infundibular outflow obstruction Hypovolemia 26 ANESTHETIC MANAGEMENT OF TOF Preoperatively – Maintain hydration – Continue beta-blockers – Avoid precipitation of a hypercyanotic attack Induction Avoid reductions in SVR IV Induction – May be more rapid, dosages may need to be reduced – Ketamine preferred choice Mask Induction – May be slower – Potential for decrease in SVR – Sevoflurane vs. Halothane 27 ANESTHETIC MANAGEMENT OF TOF Maintenance – Ketamine + nitrous oxide maintains SVR – + Volatile anesthetics – Gently titrated opioid or benzodiazepine Muscle relaxant – Avoid histamine release Ventilation – Avoid high inspiratory pressures and PEEP Avoid air embolism Hemodynamic management – Beta-blockers – Phenylephrine 28 EISENMENGER’S SYNDROME Reversal of a left-to-right shunt due to increases in pulmonary vascular resistance Once the pulmonary vascular resistance exceeds systemic vascular resistance, shunt reversal occurs Incidence Untreated VSD – 50% Untreated ASD – 10% Treatment Lung transplant with repair of VSD / ASD Heart-lung transplant 29 TRICUSPID ATRESIA Absence or non-patency of the tricuspid valve Prevents flow of blood from RA to RV Requires additional lesions for survival – RA to LA via ASD or PFO – LV to RV via VSD or LV to PA via PDA Symptoms dependent on degree of obstruction to pulmonary blood flow 30 31 TRANSPOSITION OF THE GREAT ARTERIES (D-TRANSPOSITION) Failure of spiraling of the truncus arteriosus during development Aorta arises from RV Pulmonary artery arises from LV Results in complete separation of the systemic and pulmonary circulations HINES Requires a VSD, ASD, patent foramen ovale or PDA to allow survival TRANSPOSITION OF THE GREAT ARTERIES Mortality without surgical treatment essentially 100% at 1 year Initial treatment is maintenance and/or expansion of communication between systemic and pulmonary circulations Prostaglandin E infusion – Maintain patency of PDA Balloon atrial septostomy – Increase atrial mixing Oxygen – Decreases PVR Diuretics and digoxin – If heart failure present 32 SURGICAL REPAIR OF TRANSPOSITION SWITCH vs. MUSTARD Older adults Mustard or Senning procedure – Creates a baffle of pericardium or atrial tissue that directs caval blood into the left atrium Children and young adults Arterial switch – Transect and switch the aorta and pulmonary artery – Reimplant coronaries on aorta 33 KAPLAN ANESTHETIC CONCERNS Intravenous drugs Reduced dosages due to lack of significant pulmonary circulation Inhaled drugs Delayed onset due to minimal transfer to the systemic circulation Goals Avoid myocardial depression Maintain high FiO2 Maintain hydration 34 TRANSPOSITION OF THE GREAT ARTERIES (L-TRANSPOSITION) Positions of ventricles are switched resulting in: the following blood flow – RA – mitral valve – LV – pulmonic valve – lungs – LA – tricuspid valve – RV – aortic valve – systemic Series circulation, as opposed to parallel circulation in D-Transposition allows survival and lack of symptoms for many years 35 36 TRUNCUS ARTERIOSUS Single arterial trunk overrides both ventricles Survival very low Treatment Band pulmonary arteries if pulmonary blood flow is too high Repair VSD so only LV ejects into arterial trunk Create an artificial pulmonary artery with a valve to feed the right and left PAs HINES TOTAL ANOMALOUS PULMONARY VENOUS RETURN All 4 pulmonary veins drain back into the RA or the vena cava, so oxygenated blood returns to the right heart rather than going to the systemic circulation – Requires a connection between left and right heart (VSD, ASD, PDA) for survival – Treatment involves reattachment of the pulmonary veins to the LA and closure of other defects Less severe form (partial anomalous pulmonary venous return) involves 1 or more veins rather than all 4 37 38 HYPOPLASTIC LEFT HEART Hypoplasia of: Mitral valve Left ventricle Aortic valve Blood ejected from RV into: Pulmonary arteries Systemic circulation via PDA PDA must be maintained with prostaglandin infusion HINES Multiple surgeries required for repair 39 DOUBLE AORTIC ARCH Forms a vascular ring around the trachea and esophagus producing compression Symptoms Stridor Dysphagia Treatment Resection of smaller side Postop concern HINES Tracheomalacia ALTERING PULMONARY AND SYSTEMIC VASCULAR RESISTANCE 40 SOURCES Anesthesia and Coexisting Disease. Hines, Marschall. 8th Edition. 2022 Anesthesia for Congenital Heart Disease. Andropoulos. 2nd Edition. Textbook of Medical Physiology. Guyton. 14th Edition. 2021 Kaplan’s Cardiac Anesthesia. Kaplan. 7th Edition. 2016 41