Congenital Heart Disease PDF

CONGENITAL HEART DISEASE THE FETAL CIRCULATION TRANSITION FROM FETAL TO NEONATAL CIRCULATION CONGENITAL HEART DISEASE 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 syst...

CONGENITAL HEART DISEASE THE FETAL CIRCULATION TRANSITION FROM FETAL TO NEONATAL CIRCULATION CONGENITAL HEART DISEASE 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 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 Incidence 7-10 / 1000 live births Most common form of congenital disease Chromosomal abnormalities – 10% o Majority of these associated with Trisomy 21 Multifactorial origin – 90% o Genetic + external factors § Maternal diabetes § Rubella § ETOH abuse § Lithium use INCIDENCE OF CONGENITAL HEART DISEASE SHUNTING VERSUS OBSTRUCTIVE VERSUS “OTHER” LESIONS 1 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 ACYANOTIC LESIONS ( 6 TYPES ) 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 ATRIAL SEPTAL DEFECT ATRIAL SEPTAL DEFECT 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 DOE Supraventricular dysrythmias Right heart failure Paradoxical air embolus Recurrent pulmonary infection Systemic vs. Pulmonary Vascular Resistance – Increase left-to-right shunt o Increased SVR o Decreased PVR – Decrease left-to-right shunt o Decreased SVR o Increased PVR Systemic vs. Pulmonary Blood Flow – Increased pulmonary blood flow o Possible dilution of IV drugs – Decreased systemic blood flow o Possible delay in inhalational induction 2 VENTRICULAR SEPTAL DEFECT VENTRICULAR SEPTAL DEFECT VSD SYSTEMIC VS. PULMONARY Most common congenital heart defect o But often close spontaneously in infancy o Percutaneous or open procedure Large VSD o Initial Left-to-Right shunt o Over time RVH occurs o May become a Right-to-Left shunt Surgical correction o Prior to PVR reaching 0.7 SVR 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 PATENT DUCTUS ARTERIOSUS PATENT DUCTUS ARTERIOSUS 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: Pulmonary hypertension Heart failure 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 3 AORTIC STENOSIS 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 PULMONIC STENOSIS PULMONIC STENOSIS Symptoms – Initially o Dyspnea on exertion – With development of right heart failure o Peripheral edema o Ascites – If foramen ovale is patent o Cyanosis can develop due to Right-to-Left shunting Management – Avoid decreases in systemic blood pressure – Maintain sinus rhythm with a normal heart rate – Changes in PVR not typically a problem COARCTATION OF THE AORTA COARCTATION OF THE AORTA TREATMENT & ANESTHETIC MANAGEMENT Anatomic location – Preductal o Just proximal to ductus arteriosus – Postductal o Most common o Just distal to ductus arteriosus Signs and symptoms – BP difference between upper and lower body – Hypertension, CHF, aortic dissection – Proximal to lesion o Headache, dizziness, epistaxis, palpitations – Distal to lesion o Claudication in LEs 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 o Paradoxical HTN o Effects of decreased spinal cord blood flow during cross-clamp o Abdominal pain 4 CYANOTIC LESIONS (6 TYPES) CYANOTIC LESIONS Right to Left shunt – Results in: o Decreased pulmonary blood flow o Arterial hypoxemia – Risks o Thromboembolism 20 erythrocytosis due to hypoxemia o Brain abscess Survival – Very limited in the absence of surgical correction – Requires communication of the systemic and pulmonary circulations TETRALOGY OF FALLOT TETRALOGY OF FALLOT Most common cyanotic congenital lesion Components Large, single VSD Overriding aorta Right ventricular outflow obstruction Right ventricular hypertrophy 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 SIGNS & SYMPTOMS Signs and Symptoms Systolic ejection murmur Cyanosis Increased hemoglobin and hematocrit Squatting Hypercyanotic attacks CVA Cerebral abscess Infective endocarditis RIGHT-TO-LEFT SHUNT 5 ANESTHETIC MANAGEMENT OF TOF Preoperatively – Maintain hydration – Continue beta-blockers – Avoid precipitation of a hypercyanotic attack Induction – Avoid reductions in SVR – IV Induction o May be more rapid, dosages may need to be reduced o Ketamine preferred choice – Mask Induction o May be slower o Potential for decrease in SVR o Sevoflurane vs. Halothane 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 EISENMENGER’S SYNDROME 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 o 50% – Untreated ASD o 10% Treatment – Lung transplant with repair of VSD / ASD – Heart-lung transplant TRICUSPID ATRESIA 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 6 TRANSPOSITION OF THE GREAT ARTERIES (D–TRANSPOSITION) 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 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 o Maintain patency of PDA – Balloon atrial septostomy o Increase atrial mixing – Oxygen o Decreases PVR – Diuretics and digoxin o If heart failure present SURGICAL REPAIR OF TRANSPOSITION SWITCH vs. MUSTARD Older adults – Mustard or Senning procedure o Creates a baffle of pericardium or atrial tissue that directs caval blood into the left atrium Children and young adults – Arterial switch o Transect and switch the aorta and pulmonary artery o Reimplant coronaries on aorta ANESTHETIC CONCERNS TRANSPOSITION OF THE GREAT ARTERIES (L-TRANSPOSITION) 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 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 7 TRUNCUS ARTERIOSUS 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 w/ a valve to feed the right & left PAs 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 HYPOPLASTIC LEFT HEART 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 Multiple surgeries required for repair DOUBLE AORTIC ARCH DOUBLE AORTIC ARCH Forms a vascular ring around the trachea and esophagus producing compression Symptoms – Stridor – Dysphagia Treatment – Resection of smaller side Postop concern – Tracheomalacia ALTERING PULMONARY AND SYSTEMIC VASCULAR RESISTANCE 8