Ventricular Septal Defect

VSD

1. VENTRICULAR SEPTAL DEFECT PART-I DR DHANESH KUMAR

2. Ventricular Septal Defect Henri Roger was the first man to describe a ventricular septal defect, in 1879 he wrote: “ A developmental defect of the heart occurs from which cyanosis does not ensue in spite of the fact that a communication exists between the cavities of the two ventricles and in spite of the fact that the admixture of venous blood and arterial blood occurs. This congenital defect, which is even compatible with long life, is a simple one. It comprises a defect in the interventricular septum”

3. . INTRODUCTION 2- per 1000 live birth Forms 20 % of all CHD 50 % when associated with other major defect 10-15% of large VSD’s close spontaneously 60% of defects close before age 3, and 90% before age 8

4. . Roger in 1879 - First described Eisenmenger – 1897 - Autopsy finding Pathophysiology by Abbott (1936) & Selzer (1949) 1952 – Muller and Danman - Pulmonary artery band 1954 - Lillehei and associates – First VSD repair 1956 – Dushane – Transventricular / Stirling – Transatrial 1961 – Kirklin - Repair of VSD in infants 1976 - Baratt-Boyes – Deep hypothermia & circulatory arrest HISTORICAL ASPECT

5. Formation of IV septum IV septum grows upwards from floor of the bulboventricular cavity,division into R and L . IVS meets fused AV cushions and partially fuses with them. Two ridges R and L arise in conical upper part of bulboventricular cavity , fuse with each other to form bulbar septum. Gap between the two is filled by proliferation of tissue from the AV cushions.

6. Membranous IV septum Anterior part separates RV and LV. Post. part separates RA and LV. This is because the IAS and IVS don’t meet in the midline.

7. Associated Defects Left Heart Defects Aortic stenosis (2%) Coarctation of the aorta (5%) Right Heart Defects TOF DORV Truncus Arteriosus PDA (6%) Single ventricle (e.g. Tricuspid atresia , double inlet left ventricle)

8. Chromosomal Disorders associated with VSD Trisomy 21 Trisomy 13, 18 22q11 deletion: Di George syndrome TOF is most common anomaly VSD with or without aortic arch anomaly is second most common Holt- Oram (Hand-heart syndrome): TBX5 gene found on Chromosome 12 Recurrence risk for VSD based on parental VSD Paternal 2% Maternal 6-10%

9. Ventricular Septum The membranous septum -The septal leaflet of the TV divides membranous septum into: 1. pars atrioventricularis 2) pars interventricularis . The muscular septum is a nonplanar structure that can be divided into: 1) inlet 2.) trabecular 3.) infundibular components.

10. An inlet VSD has no muscular rim between defect and AV valve annulus. The trabecular septum is largest part of IVS. Defects in the trabecular septum can be classified as anterior, midmuscular , apical, and posterior. The infundibular septum separates RV and LV outflow tracts. On the right , it is bordered by a line from the membranous septum to the papillary muscle of the conus inferiorly and the semilunar valves superiorly.

11. The Ventricular Septum

12. CLASSIFICATION ROBERT ANDERSON Perimembranous Muscular Doubly committed Juxta arterial defects VAN PRAGH AV canal type Muscular VSDs Conoventricular Conal

13. The Ventricular Septum Membranous Outflow Trabecular septum Inflow Subarterial / Supracristal

14. VSD Size(based on shunt) Restrictive VSD(Small to Moderate shunt) < 0.5 cm 2 (Smaller than AVA) Small shunt Normal RV output 75% spontaneously close < 2yrs Qp /Qs= 1.4-2.2 Psp /Asp <0.66 Non-restrictive VSD(Large shunt) > 1.0 cm 2 (Equal to or greater than to AVA) Equal RV and LV pressures Large hemodynamically significant shunt Rarely close spontaneously Qp /Qs >2.2 Psp /Asp >o.66

15. Based on size(Anatomic) 1) Large : 2/3 rd of aortic annular dia. or > 15 mm or > 1cm/sq. m of BSA Peak RV sys = LV sys pressure 2) Moderate : Half of aortic annular dia. 5 to 15 mm RV pressure to ½ of LV Qp /Qs>2.0 3) Small : One third of aortic annular dia. insufficient size to raise RV pressure & Qp /Qs < 1.75

16. Expanded Morphological Classification of VSD CLASSIFICATION EXTENSION Perimembranous Inlet, Anterior,Outlet Muscular Outlet, Trabecular , Inlet, Anterior,Apical Doubly committed subarterial Inlet septal Atrioventricular septal type Malalignment Anterior (TOF) Posterior (Interrupted arch or Coarctation ) Rotational ( Taussig -Bing)

17. Nomenclature / Classification TYPE I- Conal , Supracristal , Infundibular , Subarterial TYPE II – Perimembranous TYPE III- Inlet/ AV canal type Type IV – Muscular

18. TYPE I VSD Conal , Supracristal , Infundibular , Subarterial Maldevelopment of bulbotruncal system Located within infundibular portion of RVOT Superior margin – no muscular tissue Inferior margin – defect is muscular Can extend upto right or sometimes NCC of the aortic valve Conduction system is not in surgical proximity

19. Doubly committed subarterial VSD

20. TYPE II VSD Perimembranous type Most common (80%) Margins include membranous septum or remnant May have extensions into inlet, outlet or trabecular septum Postero -inferior margin very close to the antero-septal commissure of the TV Can extend upto non-coronary cusp of aortic valve Danger area- inferior and posterior region of defect

21. Membranous VSD

22. TYPE III VSD AV Canal type / Inlet VSDs ~5% of all VSDs Located posteriorly – subjacent to TV septal leaflet in inlet portion Superior border- may extend to the annulus of tricuspid valve Conduction system at risk – close proximity to AV node Guide- apical area of Triangle of K och Common bundle courses around inf. aspect of defect

23. Endocardial Cushion (Inlet VSD)

24. INLET VSD

25. TYPE IV VSD Muscle all around the defect May be either anterior, in the inlet septum, mid-muscular or apical Classification according to location is important because it determines the approach for surgical closure. Inlet and mid-muscular ----- RA approach Anterior ------- Rt. Ventriculotomy Apical ------ May require left ventriculotomy May be Single/ multiple Swiss Cheese VSD

26. MUSCULAR VSD

27. Pathophysiology Two determinants Size of defect PVR These determine Pressure gradient across VSD Shunt volume across VSD After birth PVR falls ------ Large flow across shunt if large VSD Causes increased PA pressure (initially flow related), increased PV return, hence LA enlargement and LV overload PAH initially flow related and reversible

28. Pathophysiology Later ----- Intimal proliferation and medial hypertrophy leads to fixed irreversible PAH Flow through the lungs decreases as PVR increases, hence shunt volume decreases Eventually PVR > SVR , hence R  L shunt across VSD  Cyanosis  Eisenmengerised VSD

29. Shunt calculated by Fick’s principle Q p /Q s Aortic O 2 % sat - Central Venous O 2 % sat Pulm . Vein O 2 % sat – Pulm . Art O 2 % sat Small VSDs - resistance to flow across the VSD hence Q p /Q s is rarely > 1.5 Moderate VSDs - Q p /Q s 1.5 - 2.5 , is less likely to cause pulmonary vascular disease

30. HEATH- EDWARD CLASSIFICATION Grade I  - hypertrophy of the media of small muscular arteries and arterioles. Grade II  - intimal cellular proliferation in addition to medial hypertrophy. Grade III  - progressive intimal proliferation and concentric fibrosis. Grade IV  - " plexiform lesions" Grade V   - angiomatous and cavernous lesions and hyalinization of intimal fibrosis. Grade VI  - necrotizing arteritis .

31. Natural History Spontaneous closure is known, primarily with perimembranous and muscular VSDs. Subarterial and inlet VSDs rarely close Chances differ with age at detection At 1 month = 80% of large VSDs close At 3 month=60% At 6 months =50 % At 12 months = 25 %

32. Natural History Patients with large VSD- symptom develop soon after birth. CHF manifested by- dyspnea on feeding/ rec. pulmonary infection / hepatomegaly /sweating/failure to thrive. Irreversible pulmonary vascular disease after 1-2 yrs of age. Some children with isolated VSD develop Subpulmonic stenosis - pt. not at risk of pulmonary vascular disease

33. CLINICAL FEATURES Grade I Small VSD (less than 1.5 cm) Patient is asymptomatic. Murmur can be present since a few days after birth.  Grade II    Frequent respiratory tract infections. CHF (rare). Cyanosis is absent even during exercise. Functional aerobic capacity is usually moderately reduced with early fatigability but unusual CHF. Grade III More frequent respiratory tract infections. Defective growth. Moderate cyanosis at times with exertion Congestive heart failure frequent in the first years of life (one of the most frequent causes of CHF during the first year of life). Functional capacity markedly reduced.  Grade IV or Eisenmenger Complex        

34. EISENMENGER COMPLEX • Infants with Eisenmenger may become easily fatigued,Cyanosed especially during crying spells and at feeding time • Low tolerance for extra exertion • Shortness of Breath ( dyspnea ) and/or rapid breathing • Fainting (syncope) • Difficulty eating, breathing or sucking • Poor weight gain • Slow growth or other physical retardation

35. CLINICAL FINDINGS Pulse pressure is relatively wide Precordium is hyperkinetic with a systolic thrill at LSB S1&S2 are masked by a PSM at LSB ,max. intensity of the murmur is best heard at 3 rd ,4 th &5 th Lt ICS . Also well heard at the 2 nd space but not conducted beyond apex Lt. 2 nd space –widely split &variable accentuated P2 Delayed diastolic murmur at the apex &S3 Presence of mid-diastolic ,low pitched rumble at the apex is caused by increased flow across the mitral valve & indicates Qp:Qs =2:1/greater Maladie de Roger –small VSD presenting in older children as a loud PSM w/o other significant hemodynamic changes

36. ECG CHEST X-RAY May show right/left or combined ventricular hypertrophy Presence of RAD represents elevated RVP and PAP Cardiomegaly : proportional to the volume overload. Mainly LV, LA and RV enlargement. Increased pulmonary blood flow , PAH. Unless LA is significantly enlarged its difficult to differentiate from ASD. RV may not be as enlarged as anticipated as it receives the shunt into its outflow tract.

37. Ventricular septal defect in a 7-month-old. Frontal(A)and lateral (B) views of the chest show moderate cardiac enlargement including right atrial , right ventricular, and left atrial enlargement with posterior displacement of the left main stem bronchus (arrow in B) and increased pulmonary vascularity

38. VSD IN ADULT PSVT & AF prevalent with increasing age. VSD+ AR – High risk of bacterial endocarditis Right sided failure- due to pulmonary stenosis Left sided failure- with assoc. aortic valve prolapse . Eisenmenger complex- 2 nd & 3 rd decade of life Pregnancy- spontaneous abortion/small-for-date babies Mortality- 27% by 20 years & 69% by 60 years.

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