E

Absence of septum secundum

Septum primum

Atrial septal defect

Septum primum

Atrial septal defect

Septum primum

Absence of septum primum and septum secundum

Figure 11.19 A. Normal atrial septum formation. B and C. Ostium secundum defect caused by excessive resorption of the septum primum. D and E. Similar defect caused by failure of development of the septum secundum. F. Common atrium, or cor trilocu-lare biventriculare, resulting from complete failure of the septum primum and septum secundum to form.

component, separated by abnormal valve leaflets in the single atrioventricular orifice (Fig.11.20C).

Occasionally, endocardial cushions in the atrioventricular canal partially fuse. The result is a defect in the atrial septum, but the interventricular septum is closed (Fig. 11.20, D and E). This defect, the ostium primum defect, is usually combined with a cleft in the anterior leaflet of the tricuspid valve (Fig. 11.20C).

Tricuspid atresia, which involves obliteration of the right atrioventricular orifice (Fig. 11.21 B), is characterized by the absence or fusion of the tricuspid valves. Tricuspid atresia is always associated with (a) patency of the oval foramen, (b) ventricular septal defect, (c) underdevelopment of the right ventricle, and (d) hypertrophy of the left ventricle.

Was this article helpful?

0 0
Peripheral Neuropathy Natural Treatment Options

Peripheral Neuropathy Natural Treatment Options

This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.

Get My Free Ebook


Post a comment