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Congenital Heart Disease: Causes, Types, and Management
Jul 17, 2024
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Congenital Heart Disease: Causes, Types, and Management
Factors Leading to Congenital Heart Disease
Genetic Predisposition
Children with trisomy 21 (Down syndrome) are more prone to congenital heart disease.
Environmental Risk Factors
Viral infections, drug toxins:
Taken by mothers, especially diabetic mothers, increase risk.
Higher incidence in heterozygous mothers in Finland.
Classifications of Congenital Heart Disease
Increased Pulmonary Blood Flow
Any communication from left side to right side: ASD (Atrial Septal Defect), VSD (Ventricular Septal Defect), PDA (Patent Ductus Arteriosus).
Transpositions of main vessels.
Decreased Pulmonary Blood Flow
Blood doesn’t reach pulmonary circulation, e.g., right-to-left shunt:
Tetralogy of Fallot (ToF).
Pulmonary atresia.
Tricuspid atresia.
Obstructive Lesions
Aorta:
Coarctation of the aorta.
Pulmonary artery:
Pulmonary stenosis.
Cardiomyopathy.
Fundamentals of Venous and Arterial Circulation
Normal Circulation
Venous Return:
IVC/SVC to Right Atrium (RA), then pulmonary artery.
Effective Pulmonary Blood Flow (QP):
Blood flow from venous system to arterial pulmonary system.
Effective Systemic Blood Flow (QS):
Blood flow from pulmonary vein to systemic artery (aorta).
In normal circulation, QP = QS (1:1 ratio).
Shunting
Left-to-Right Shunt:
E.g., ASD, VSD, PDA.
Increased pulmonary blood flow (QP > QS).
Symptoms: Volume overload, heart failure, increased pulmonary circulation.
Right-to-Left Shunt:
E.g., Tetralogy of Fallot (ToF).
Decreased pulmonary blood flow (QP < QS).
Symptoms: Cyanosis (poorly oxygenated blood in systemic circulation).
Tetralogy of Fallot (ToF)
Definition
Four components:
Large, non-restrictive VSD.
Right ventricular outflow obstruction (Infundibular stenosis).
Overriding aorta.
Right ventricular hypertrophy.
Classification
Pink ToF:
Minimal right ventricular obstruction.
Blue ToF:
Severe obstruction.
Profound Cyanosis:
Extreme obstruction or atresia of pulmonary valve.
Symptoms and Signs
Signs:
Central cyanosis, clubbing, single S2 sound, ejection systolic murmur.
Symptoms:
Dyspnea, poor feeding, sweating, tachycardia, cyanotic episodes (Tet spells).
Complications
Polycythemia:
Increased red blood cell count leading to sludging and thromboembolism.
Cerebral abscess:
Common non-cardiac surgical emergency.
Heart Failure:
Due to increased right ventricular pressure.
Management
Preoperative Care
Avoid Hypovolemia:
Maintain hydration.
Pre-medication:
Reduce anxiety and prevent catecholamine release.
Antibiotic Prophylaxis:
Prevent bacterial endocarditis.
Intraoperative Management
Anesthetic Choice:
Ketamine preferred for maintaining systemic vascular resistance (SVR); avoid reducing SVR.
Avoid Hypoxia, Hypercarbia, Acidosis:
Use oxygen and correct acidosis.
Right Ventricular Outflow Tract Function:
Monitor with echocardiography.
Avoid Air Bubbles:
Prevent paradoxical embolism.
Treating Tet Spells
Calm the child.
Squatting or knee-chest position.
Oxygen administration.
Fluid bolus:
Increase RV stroke volume.
Phenylephrine:
Increase SVR.
Beta-blockers:
Reduce infundibular spasm.
Sedation as needed:
Morphine or ketamine.
Postoperative Management
Pain Management:
Avoid regional blocks that decrease SVR.
Hydration:
Maintain adequate fluid balance.
Monitor for Arrhythmias:
Common post-surgical complication.
Conclusion
Key management strategies for congenital heart diseases, focusing on Tetralogy of Fallot.
Always aim to balance systemic and pulmonary vascular resistances, particularly note the differences between left-to-right and right-to-left shunts.
Important to control right ventricular pressure and ensure proper blood flow to the lungs.
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