Persistant left cranial vena cava

Persistent Left Cranial Vena Cava and Right Cranial Vena Cava Aplasia in a French Bulldog and a Cavalier King Charles Spaniel with Severe Pulmonic Stenosis

J. Huynh, E.J. Benjamin, K. Degarmo, R. Baumwart.

Background
Persistent left cranial vena cava (PLCVC) is a rare congenital vascular anomaly in dogs where the left cranial cardinal vein fails to regress, maintaining a connection to the right atrium through the coronary sinus (CS). This anomaly is usually asymptomatic but can complicate cardiovascular interventions, particularly catheter-based procedures. Right cranial vena cava (RCVC) aplasia, the absence of the right cranial vena cava, is even rarer and can further complicate procedures like pulmonary balloon valvuloplasty (PBV). This case report describes two dogs diagnosed with severe pulmonic stenosis, where unexpected PLCVC with RCVC aplasia was identified during attempted PBV.

Methods
Two dogs—a 7-month-old French Bulldog and a 1-year-old Cavalier King Charles Spaniel—were referred for PBV due to severe pulmonic stenosis. Both dogs underwent a full diagnostic workup, including transthoracic echocardiography (TTE), agitated saline contrast studies, and fluoroscopic angiography. The anatomical anomalies were only confirmed during catheterization attempts, highlighting challenges in preoperative diagnosis.

Results
In both cases, a dilated coronary sinus was identified on TTE, suggesting PLCVC. However, RCVC aplasia was not detected preoperatively and was discovered only when right jugular venous catheterization failed. Fluoroscopic angiography confirmed the absence of the RCVC and the presence of a large PLCVC draining into the CS. This altered the procedural approach, requiring a femoral vein catheterization instead of the traditional right jugular vein approach for PBV. Both procedures were completed successfully, and postoperative echocardiography showed improved pulmonary valve gradients (French Bulldog: 230 mmHg to 82 mmHg; Cavalier King Charles Spaniel: 83.5 mmHg to 66 mmHg).

Limitations
The study involved only two cases, limiting generalizability. The anomalies were only definitively diagnosed intraoperatively, indicating limitations in routine preoperative imaging techniques. Additionally, long-term follow-up was not available to assess clinical outcomes beyond the immediate postoperative period.

Conclusions
PLCVC with RCVC aplasia is a rare but clinically significant anomaly that can interfere with catheter-based interventions like PBV. A dilated coronary sinus on echocardiography should raise suspicion for PLCVC, and agitated saline contrast studies via bilateral cephalic veins may help detect RCVC aplasia. When these anomalies are present, a femoral vein approach may be preferable to avoid procedural complications. Preoperative recognition of these anomalies could reduce anesthetic time, procedural complications, and resource use.

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