Conduction tissue anomalies in absence of the right superior caval vein

Area of Science:

• Cardiology
• Cardiac Electrophysiology
• Congenital Heart Abnormalities

Background:

• Patients with absent right superior caval vein and persistent left superior caval vein exhibit high rates of cardiac electrical instability.
• A large coronary sinus has been hypothesized to increase susceptibility to arrhythmias.

Purpose of the Study:

• To investigate the conduction tissues, specifically the sinus node and atrioventricular junction, in hearts with persistent left superior caval vein and/or absent right superior caval vein.
• To determine if coronary sinus size influences cardiac conduction tissue histology and electrical stability.

Main Methods:

• Examination of conduction tissues from 8 hearts with congenital anomalies (persistent left superior caval vein, absent right superior caval vein).
• Histological evaluation of the sinus node and atrioventricular junctional area.
• Comparison of findings with known normal cardiac conduction tissue anatomy.

Main Results:

• Six specimens had a persistent left superior caval vein connecting to the coronary sinus.
• Four specimens had an absent right superior caval vein; 3 of these also had a persistent left superior caval vein.
• Coronary sinus size did not affect the histology of adjacent conduction tissues.
• The sinus node was abnormal in 3 out of 4 hearts with an absent right superior caval vein.

Conclusions:

• Absence of the right superior caval vein is associated with sinus node abnormalities.
• Sinus node dysfunction, secondary to absent right superior caval vein, is a potential cause of cardiac arrhythmias in these patients.
• Coronary sinus size is not a primary factor in the observed conduction tissue abnormalities.