Congenital Anomalies of Heart

Congenital anomalies of the heart and blood vessels arise during the 1st 10 wk of embryonic development

Present at birth.

The incidence is 1/120 live births;

Estimated risk is 2 to 3% in children with an affected 1st-degree relative.

Aetiology

About 5% of patients have a chromosomal abnormality (eg, trisomy 13, 18, or 21, Turner's syndrome);

May be part of a genetic syndrome (eg, Holt-Oram syndrome).

Maternal illnesses (eg, diabetes mellitus, SLE, rubella),

Environmental exposure (eg, to thalidomide)

Usually, no specific cause is identified.

The anomalies

Atrial Septal Defect

A defect in the interatrial septum.

Enables blood flow between the left and right atria.

The mixing of arterial and venous blood may become hemodynamically significant.

This mixing of oxygenated and deoxygenated blood may result in a "shunt". The amount of shunting present dictates hemodynamic significance.

A "right-to-left-shunt" typically poses the more dangerous scenario.

In the intrauterine life , the interatrial septum develops and separates the left and right atria. The foramen ovale remains open during fetal development to allow blood from the venous system to bypass the lungs directly and enter the circulatory system. This is because the oxygen content of the fetal arterial system is provided by the placenta, as the lungs of the fetus are nonfunctional.

A layer of tissue begins to cover the foramen ovale during fetal development, in which typically, after birth, the pressure in the pulmonary circulatory system drops, thus causing the foramen ovale to close entirely. In a few, the foramen ovale does not entirely seal. This is known as a patent foramen ovale (PFO).

This extra blood from the left atrium may cause a volume overload of both the right atrium and the right ventricle, which if left untreated, can result in enlargement of the right side of the heart and ultimately heart failure.

There are many types of ASD. Ostium secundum atrial septal defect is the most common type of atrial septal defect

ostium primum atrial septal defect is commonly known as atrioventricular septal defect.

Symptoms and signs

Dyspnea on exertion

Congestive heart failure

Cerebrovascular accident (stroke).

Atrial fibrillation.

Ejection systolic murmur due to the increased flow of blood through the pulmonic.

Fixed splitting of S2.

Investigations

In transthoracic echocardiography, an atrial septal defect may be seen on color flow imaging as a jet of blood from the left atrium to the right atrium.

Transoesophsgeal echocardiography may also be done.

The ECG findings: prolonged PR interval (a first degree heart block)

Primum ASD - a left axis deviation of the QRS complex

Secundum ASD - a right axis deviation of the QRS complex.

Sinus venosus ASD - a left axis deviation of the P wave (not the QRS complex).

Treatment

Surgical mortality is lowest when the procedure is performed prior to the development of significant pulmonary hypertension.

pulmonary artery systolic pressure of less than 40 mmHg - the lowest mortality

Surgical closure of an ASD with a patch under direct visualization.

Percutaneous closure of an ASD - only secundum ASDs with a sufficient rim of tissue around the septal defect

Percutaneous closure is the method of choice in most centres.[12]

Ventricular Septal Defect