Persistent Left Cranial Vena Cava and Its Association with Cardiac Conduction Abnormalities in Five Dogs
Persistent left cranial vena cava (PLCVC) is an uncommon congenital anomaly of the thoracic venous system both in dogs and humans, which causes dilatation of coronary sinus (CS).
This report describes PLCVC in a series of five brachycephalic dogs, including history, concurrent cardiopulmonary (CP) diseases, and diagnostic imaging findings.
The report evaluates PLCVC with different cardiac disease status associated with difference in CS dilatation and cardiac conduction abnormalities.
Inclusion criteria of PLCVC were met by confirmation through contrast echocardiography and computed tomography (CT) in five dogs. Three of five PLCVC dogs had pulmonary hypertension (PH) and tricuspid valve insufficiency (TVI). In contrast, two PLCVC dogs had mitral valve degeneration (MVD) or mitral valve insufficiency (MVI). All cases underwent ECG, contrast echocardiography and CT scan.
The size of CS was significantly dilated at least three times more in PLCVC dogs with PH and TVI than from the other two PLCVC dogs with MVD or MVI. In addition, arrhythmias, second-degree AV block, occurred in three PLCVC dogs concurrent with PH or TVI in contrast to a normal sinus rhythm in a PLCVC dog with MVD or MVI.
Coronary sinus dilatation resulting from PLCVC could be aggravated by concurrent CP diseases which could cause right atrium enlargement such as TVI or PH, resulting in disturbance of cardiac conduction as varying degrees of AV block. Also, as presence of PLCVC is related to genetic factors, all five dogs in this case suggest that brachycephalic breeds could be predisposed.