Congenital Heart Disease Conrad Cheung, MD Marie Sankaran, MD Department of Anesthesiology Boston University Medical Center Faculty Advisor: Elena Brasoveanu, MD March 9, 2006
Classification Acyanotic – Interrupted Aortic Arch – Aortic Stenosis – Ventricular Septal Defect – Atrial Septal Defect Cyanotic Defects – Hypoplastic Ventricle – Pulmonary Stenosis – Tetralogy of Fallot – D transposition of the great vessels – Tricuspid atresia
Plan We will discuss few topics that are important from the anesthesiologist point of view – Septal Defects – Atrial Septal Defects – Patent Ductus Arteriosus – Interrupted Aortic Arch – Tetralogy of Fallot – Single ventricle
The Cyanotic Neonate Ductus Arteriosus closes within 6 hours of birth so any congenital heart disease that relies on it for perfusion of oxygenated blood will present early To prevent death from inadequate oxygenation, the duct has to be maintained open with prostaglandines Any neonate with a congenital heart disorder that relies on an open ductus arteriosus for oxygenation will deteriorate rapidly and requires immediate transfer to a specialty center
Ventricular Septal Defect I Defect in the septum separating the left and right ventricles Most common type of congenital heart disease accounting for 21% of all cases Can occur singly or in multiples anywhere along the ventricular septum Small defects often close spontaneously in the first 2 years of life while large defects require surgical repair within the 1st year
Ventricular Septal Defect II Prevalence equal between boys and girls Due to increased pressures in the left ventricle, left to right shunting of oxygenated blood occurs With the increased pulmonary blood flow, pulmonary hypertension can occur with large defects
Symptoms of Ventricular Septal Defects Rapid breathing Irritability Excessive Sweating Poor weight gain Congestive Heart Failure, usually within 6 to 8 weeks of life if defect is large Pulmonary Hypertension if defect is large
Treatments for Ventricular Septal Defects Lasix and Aldactone to decrease symptoms of CHF Digoxin to increase effectiveness of myocardial function If surgery needed, patching or suturing the defect can be done Mortality from surgery is low
Atrial Septal Defect I Defect in the septum separating the left and right atria Accounts for 5-10% of congenital heart disease Twice as frequent in girls versus boys Three types of atrial septal defects
Atrial Septal Defect II Ostium Primum: Defect located in the lower part of septum near tricuspid valve which separates the right atrium and right ventricle Ostium Secundum: Defect located near center of atria septum (most common accounting for 50-70% of atrial defect) Sinus Venosus: Located near the SVC or IVC’s entrances to the heart
Atrial Septal Defect IV Due to increased pressures, there is left to right shunting of oxygenated blood If large defect, can cause enlarged right atria, right ventricle, and pulmonary artery resulting in abnormal arrhythmias CHF can occur if left untreated till adulthood
Symptoms of Atrial Septal Defects Slender build Heart murmur resulting from increased blood flow through pulmonary valve Usually no significant exercise restriction unless defect is large. SOB or palpitations are possible.
Treatment of Atrial Septal Defects If defect is small (less than 2mm), will usually resolves spontaneously If defect is large, surgical correction is needed Minimally invasive procedures available Transcatheter devices, such as a septal occluder may be used
Patent Ductus Arteriosus The ductus arteriosus connects the pulmonary artery to the descending aorta during fetal life. PDA results when the ductus fails to close after birth.Picture: www.lpch.org
Patent Ductus ArteriosusPathophysiology: – Blood flows from aorta to the pulmonary artery, creating a left to right shunt, resulting in left atrium and ventricle overload. – Increased pulmonary blood flow can result in pulmonary hypertension and reversal of the shunt, which is known as Eisenmenger’s Syndrome. This results in flow of desaturated blood to the lower extremities. Picture: www.lpch.org
Patent Ductus Arteriosus Symptoms: – Children with small patent ductus are usually asymptomatic. – Large left to right shunts develop symptoms of congestive heart failure such as tachypnea, tachycardia, poor feeding and slow growth Physical exam: – Continuous murmur heard best at the left sternal border.
Patent Ductus Arteriosus Lab Studies: – CXR: enlarged cardiac silhouette secondary to left atrial and ventricular enlargement with prominent pulmonary vascular markings. – EKG: left atrial enlargement, LVH – ECHO: doppler flow through the ductus Treatment: – Surgical division or ligation of the PDA
Patent Ductus Arteriosus Anesthetic Management: -Maintain high arterial pressures as low diastolic pressure and pulmonary steal can result in decreased organ perfusion. Concerns After Repair: – Rarely, recanalization or incomplete ligation of the ductus occur. – Post repair, these patients can be treated as healthy patients and do not require endocarditis prophylaxis.
Interrupted Aortic Arch I Relatively rare occurs in 2 cases per 100,000 live births Consists of 2 different defects: divided aortic arch and ventricular septal defect Divided Aortic arch results in continued blood flow to the upper extremities, but none to the lower extremities
Interrupted Aortic Arch II Lower extremities oxygenated due to the combination of patent ductus arteriosus and ventricular septal defect PDA connects lower portion of the aortic to the pulmonary artery VSD allows travel of oxygenated blood to the right ventricle which in turns travels to the pulmonary artery.
Symptoms of Interrupted Aortic Arch I Often discovered 3-4 days after birth when the patent ductus arteriosus closes Symptoms of shock develops very rapidly as no oxygenated blood flows to the lower extremities Rapid breathing, clammy sweating, and poor feeding often develops during the first week
Symptoms of Interrupted Aortic Arch II Most babies born at term with normal length and weight Heart murmur usually heard Liver may be enlarged Left arm/leg pulses may be diminished or absent Echocardiogram for diagnosis
Treatment of Interrupted Aortic Arch Before surgery, try to keep the PDA open to provide oxygenated blood to the lower extremities Surgery to suture together the two ends of the aorta, patch the VSD, and ligate the PDA 85-90% patients survive the hospital stay
Long Term Prospects for Interrupted Aortic Arch Patients are at increased risk for subacute bacterial endocarditis requiring antibiotics before surgery and dental work Restriction from vigorous or competitive sports. Emphasis placed on child to self- limit their level of exertion
Tetralogy of Fallot Pathophysiology:Increased resistance by the pulmonary stenosis causes deoxygenated systemic venous return to be diverted from RV, through VSD to the overriding aorta and systemic circulation systemic hypoxemia and cyanosisPicture: www.lpch.org
Tetralogy of Fallot Symptoms: – Dyspnea on exertion or when crying – Tet spells: irritability, cyanosis, hyperventilation and sometimes syncope or convulsions due to cerebral hypoxemia. – Patients learn to alleviate symptoms by squatting which increases systemic resistance and decreases the right-to-left shunt and directs more blood to the pulmonary circulation.
Tetralogy of Fallot Physical exam: – Clubbing of the fingers and toes – Systolic ejection murmur heard at the upper left sternal border created by turbulent blood flow through stenotic RV outflow tract Lab Studies: – CXR: prominent RV – EKG: RVH, right axis deviation – ECHO: displays and quantifies extent of RV outflow tract obstruction
Tetralogy of Fallot Treatment: – Surgical closure of the VSD and enlargement of the pulmonary outflow tract Anesthetic Management: -The goal is to control the magnitude of the right to left intracardiac shunt, which is increased by: 1) Decreased SVR 2) Increased PVR 3) Increased myocardial contractility -Patient given beta blockers for prophylaxis against Tet spells -Inhalation induction can be employed in an attempt to avoid Tet spells while placing an intravenous line. -Physiologic monitoring includes standard ASA monitors and an arterial line. Echocardiography and EEG may also be employed.
Tetralogy of Fallot Concerns After Surgical Repair: – Endocarditis prophylaxis – Residual VSD secondary to incomplete closure – Residual RV outflow tract obstruction – Chronic pulmonary valve regurgitation results in a large volume load on the right ventricle that can lead to cardiomegaly and increased incidence of arrhythmias. – Right ventriculotomy during the repair leads to scarring which increases the risk of dysrhythmias and conduction abnormalities. Overall incidence of sudden death in TOF patients after surgical repair is about 0.3%.
Single Ventricle Physiology Group of congenital heart disease Instead of 2 separate ventricles, there is essentially 1 ventricle pumping blood to the aortic and pulmonary artery Complete mixing of oxygenated and deoxygenated blood occurs
Examples of Single Ventricle Congenital Processes Tricuspid atresia: Narrowed pulmonary arteries. At Birth patent PDA allows sufficient oxygenation to occur, however after closure of PDA cyanosis results Hypoplastic Left heart: Blood flow to the body severely restricted. Once PDA close, patient has profound shock
Treatment of Tricuspid Atresia Blalock-Taussig shunt placed to form a conduit between pulmonary artery and aorta to maintain oxygenation Prior to surgery, maintain PDA patency
Treatment of Hypoplastic Left Heart Keep PDA patent prior to procedure to prevent patient from going into shock Aorta is formed from the base of the pulmonary artery and narrowed aorta Modified Blalock-Taussig shunt formed to maintain adequate oxygenation
Long Term outlook of Single Ventricle Activity limitations Prophylactic antibiotics prior to surgery and dental work Life-long checkups and medications Prone to rhythm disturbances, fluid retention, and increased risk of CHF
Anesthetic Considerations for Non-Cardiac Surgery in Patients with Congential Heart Disease Has the heart defect been corrected? If so, what kind of follow-up has the patient had? Should the surgery be done at a specialized center with expertise in congential heart disease? Will a cardiology consult be needed to help plan the anesthetic management?
Anesthetic Considerations for Non-Cardiac Surgery in Patients with Congential Heart Disease II Pre-op the patient as you would any other with special emphasis on the heart What is the patient’s functional capacity? Any recent echos or EKGs? Patients with a history of ASD or VSD repairs are prone to arrhythmias and endocarditis