Valvular and Congenital Heart Disease

Patients that have valvular or some form of congenital heart disease have an excess strain situation that is particularly susceptible to the effects of increased exercise and blood shifting into the heart and lungs due to water immersion.

Atrial or ventricular septal defects.

In divers with atrial or ventricular septal defects, during decompression, there is a risk of bubbles getting into the arterial circulation without the filtering effect of the lungs, causing cerebral embolization and cerebral stroke. Since intra-atrial and intraventricular shunts can be bidirectional at different phases of the cardiac cycle, presence of an atrial or ventricular septal defect is a contraindication to diving.

Aortic stenosis, mitral stenosis, aortic coarctation, or pulmonic stenosis

Patients with circulatory obstruction such as aortic stenosis, mitral stenosis, aortic coarctation, or pulmonic stenosis have limitations to exercise because of the narrowed segment of the circulation.

When the circulatory demand and cardiac output differs, blood pressure will fall and the patient will develop syncope (fainting). This is the probable mechanism for sudden death in patients with narrowed aortic valve (aortic stenosis). These patients should not be approved for diving.