Ventricular septal defect

Ventricular Septal Defect

1. Ventricular Septal Defect Dr. Abdullah Al Mamun Honorary Medical Officer Cumilla Medical College Hospital

2. Definition VSD is a developmental defect in the interventricular septum allowing shunt between the left & right ventricles.

3. Development At 4-8 weeks of gestation, the single ventricular chamber is effectively divided into two chambers. This division is accomplished with the fusion of the membranous portion of the interventricular septum, the endocardial cushions, and the bulbous cordis. Failure of development or fusion of one of the above components during morphogenesis of the embryonic heart results in a VSD in the corresponding component.

4. Epidemiology Most common cardiac malformation. It accounts for 25% of all congenital heart disease. VSDs are the most common lesion in many chromosomal syndromes, including trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome), trisomy 21 (Down syndrome).

5. Types According to location of the defect: Perimembranous (most common) Muscular or Trabecular Outlet VSD (Supracristal/ Infundibular) Inlet VSD (AV canal type)

6. Types According to size of the defect: Small (<5 mm) Moderate (5-10 mm) Large (>10 mm) According to haemodynamic status: Restrictive: Small defect, shunt is limited. Non-restrictive: Large defect, shunt is not limited.

7. Pathophysiology The pathophysiologic effects of a VSD derive from the effects of the left-to-right shunt. A left-to-right shunt at the ventricular level has following hemodynamic consequences: Increased LA & LV volume load > LA & LV hypertrophy Excessive pulmonary blood flow > Pulmonary HTN Reduced systemic cardiac output

8. Pathophysiology Eisenmenger’s syndrome Left to Right shunt Increased pulmonary blood flow Endothelial dysfunction & pulmonary vascular remodeling Increased pulmonary vascular resistance Inversion of shunt: Right to Left

9. Natural History Spontaneous closure occurs in about 50% of cases by 1 year. Congestive Cardiac Failure (CCF) develops in large VSD after 8 weeks of age. In a large VSD, the shunt may reverse as early as 6-12 months of age, but Eisenmenger’s syndrome does not get established till the teenage years. Rarely, Infective endocarditis develop in VSD patients.

10. Clinical Features: In small defect: Usually asymptomatic Normal growth and development. Incidental detection of a pansystolic murmur at left 3rd and 4th intercostal spaces.

11. Clinical Features: Symptoms appear in large defect: Dyspnoea Feeding difficulties Poor weight gain Easy fatigability Profuse perspiration Recurrent respiratory tract infections Cyanosis is usually absent in early stage

12. Clinical Features: General examination: Appearance: Sick looking, often malnourished. Tachypnoea Tachycardia Blood pressure: Normal JVP: May be raised in CCF Pedal oedema: May be present in Heart Failure

13. Clinical Features: Precordium examination: Inspection: Hyperdynamic May be bulged Palpation: Apex beat is thrusting, shifted to the left. Left parasternal heave may be present. Thrill may be present in tricuspid area. Palpable P2 may be present.

14. Clinical Features: Precordium examination: Auscultation: 1st & 2nd heart sounds are audible in all 4 areas A harsh, pansystolic murmur (Grade 4/6) best heard at lower left sternal border at the 3rd, 4th & 5th intercostal spaces. The murmur may radiate to the right lower sternal border. Intensity varies based on the size of the VSD and pulmonary vascular resistance.

15. Investigations: Chest X-ray: In small defects: May be normal. In large defects: Cardiomegaly. Increased pulmonary vascular markings.

16. Investigations: ECG: Normal in small defect. Left ventricular hypertrophy in large VSD Biventricular hypertrophy when associated with pulmonary hypertension. P wave may be notched when there is left atrial enlargement.

17. Investigations: Echocardiogram: Shows location & size of the defect. Shows direction of blood flow. Cardiac catheterization: Measurement of intracardiac & intravascular oxygen content defines the magnitude & direction of shunting.

18. Treatment: Counselling: For small defects: Reassurance of parents Encouraged to live a normal life No restrictions on physical activity For large defects: Parents should be counselled about its complications & prognosis.

19. Treatment: Medical Management: Adequate nutrition Maintenance of good dental hygiene Antibiotic prophylaxis against Infective Endocarditis Treatment of CCF: Loop diuretics: Frusemide ACE inhibitors: Enalapril, Captopril Inotropic agents: Digoxin

20. Treatment: Surgical Management: As 50% of VSD close spontaneously by 1st year, patients with small & moderate defects should be kept in regular follow-up to observe spontaneous closure. In patients with large defects, surgical repair has to be done before irreversible damage to the pulmonary vasculature occurs.

21. Treatment: Indication of surgery: At any age: Patients with large defect in whom clinical symptoms & failure to thrive can not be controlled medically. <6 months: If patient develops CCF which does not respond to decongestive therapy. After 6 months: Large defects with pulmonary hypertension, even if the symptoms are controlled by medication.

22. Indication of surgery: Significant L-R shunt with Qp : Qs > 2 : 1 Patients with a Supracristal VSD of any size should be operated because of high risk for aortic valve regurgitation. Contraindication of surgery: Large VSD with predominant Right to Left shunt Small VSD with no CCF and Qp : Qs < 1.5 : 1 Risk of surgery: The rate of surgical mortality is < 2%

23. Prognosis: The results of primary surgical repair are excellent and complications leading to long term problems are rare. After surgical obliteration of left to right shunt: The hyperdynamic heart becomes quiet Cardiac size decreases toward normal Thrills & murmurs are abolished Pulmonary arterial hypertension regresses The long term prognosis after surgery is excellent.

24. Complications Complications of VSD: Congestive cardiac failure Eisenmenger’s syndrome Aortic regurgitation Complications of surgery: Infection Post operative hemorrhage Pulmonary hypertension Valve injury AV block Residual VSD

25. VSD & Endocarditis According to the most recent recommendations of the American Heart Association - Unrepaired VSDs don't require endocarditis prophylaxis, After the VSD is successfully closed, preventive treatment is needed only during a six-month healing period.

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