Congenital heart disease part 2.

Left to Right shunt (acyanotic initially - no central cyanosis in early stages of life)

1. Patent Ductus Arteriosus - connection between pulmonary artery and arch of aorta does not close after birth. normally closes due to increase O2 tension, decreased pulmonary vascular resistance and decreased PgE. ductal closure may be delayed due to hypoxia, prematurity or cardiac disease. treatment - surgery or Pg inhibitors. Machinary like murmur common.

2. Atrial Septal Defect (ASD) - abnormal opening in the interatrial septum. Asymptomatic till adulthood. 4 major types - Ostium primum type, ostium secundum type, patent foramen ovale and sinus venosus defect.

• 1. Ostium primum type - infrequent, involves region adjacent to endocardial cushions. there are clefts in the anterior leaflet of the mitral valve and the septal leaflet of the tricuspid valve.

• 2. Ostium Secundum type - most common. Is due to a true defieciency in interatrial septal wall (unlike patent foramen ovale) and varies in size. shunting of blood from ledt to right, increases the blood volume and blood pressure in the right side of the heart, leading to an increase in diameter of the pulmonary artery than the aorta.
  

• 3. patent foramen ovale - found in 25% of adults and is normally not functional. if it is, paradoxical embolism can occur. Paradoxical embolism is when a thrombus from DVT travels to the right side of the heart, travels through the ASD, where it enters the left atrium, left ventricle and aorta where it enters the systemic circulation.

• 4. sinus venosus defect - uncommon, upper part of interatrial septum is affected.

Complications of ASD - paradoxical embolism, pulmonary hypertension- eft to rght shunt - more blood into right side of heart, more blood to lungs, pressure in lungs increase), right ventricular hypertrophy (more blood, compensatory hypertrophy of RV), heart failure, bacterial endocarditis.

3. Ventricular Septal Defect - intraventricular muscular ridge grows from apex towards endocardial cushions, membraneous portion last to form and is the most common site for VSD. if large/ do not close, reversal of flow (R-L shunt) and cyanosis occurs

EISENMENGER COMPLEX - reversal of shunt.

4. AV septal defect

Mnemonic for Left to Right shunt - PAVA