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VENTRICULAR SEPTAL DEFECT

This is commonest congenital disorder which accounts for 30%, but when it is acquired, it may be due to postmyocardial infarction or the rupture of interventricular septum.

Anatomically interventricular septum can be divided into fibrous and muscular components. Fibrous components are termed as membranous septum, whereas, muscular components have three parts:
  • Inlet septum
  • Apical trabecular
  • Outlet septum
Circulatory disorders depend upon the size and duration of defect. If the defect is small Left-to-Right shunting occurs. If the defect is large, then interventricular connection develops, pressure gradient in left and right ventricles diminishes and even absent. Small defects are restrictive. Here the lung resistance rate has main importance. To start within smaller defects and low lung resistance, greater work is done by left ventricle. Due to increased pressure in the left ventricle, blood passes from left to right ventricle, later on, pulmonary hypertrophy. Here as the pressure increases in right ventricle, blood then flows from right to left i.e. reversal shunt. This causes appearance of cyanosis and clubbing.

If PAP is more than 10 units, blood flow in shunt changes its direction and becomes bidirectional. As pressure predominates, Eisenmenger’s phenomenon develops i.e. cyanosis polycythemia and weakness.

Clinical features:
Dyspnea and heart failure are prominent features.

General Physical Examination:
  • Child has retarded growth
  • Pulse is of high volume and bounding “Water-hammer” pulse may be present
  • Cyanosis and clubbing
  • Jugular venous pressure (JVP) may be raised in case of heart failure
Inspection of precordium:
This shows apex beat shifted outside the midclavicular line. Pulsations are visible at lower sternal angle.

Auscultation:
Pan-systolic murmur is heard along left lower sternal border.

Treatment:
is only surgical before pulmonary hypertension develops.
Sternostomy is done, where, heart should be opened via Right atrium and Left ventricle and then the appropriate prosthetics are applied.

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This article has been written by Dr. M. Javed Abbas.
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19:34 09/02/2003