[Congenital aneurysm of the membranous interventricular septum].

In a 50-year-old patient with complex ventricular arrhythmia (monotopic ventricular extrasystoles in bigeminy and triplet form), coronary angiography with ventriculography revealed an aneurysm of about 2-3 cm diameter that bulged visibly into the right ventricle during the systole. Electrophysiology was able to localise the earliest excitation during the ventricular extrasystoles at the septal border of the aneurysm. Hence, the congenital aneurysm was definitely identified as the source of the arrhythmia. Surgery or drug therapy were not indicated since there was no haemodynamically effective ventricular tachycardia in the patient who was largely free from complaints.