Cannulation of a Persistent Left Superior Vena Cava
A Clue Given by ECG Guidance
Electrocardiographically guided central venous catheter (CVC) placement is a well-established method in Europe. Atypical P-wave forms may indicate special anatomic variations.
This case report demonstrates the P-wave pattern during insertion of a CVC in a patient with unknown persistent left superior vena cava. Knowledge of variations in P-wave patterns increases the understanding on ECG-guided CVC placement and will enable safer placement of CVCs and pacemakers.
A 42-year-old man was scheduled for reconstruction of the aortic valve. A CVC and a pulmonary artery catheter were inserted through the left internal jugular vein. The CVC was advanced under ECG guidance (Einthoven lead II). An unusual pattern of P-wave changes with advancement of the CVC was noted.
Instead of a positive P wave that was expected with an insertion depth of 10 cm, a negative deflection was observed. During further advancement, the P-wave amplitude increased significantly and became biphasic; it never turned positive. The maximal deflection was noted at an insertion depth of 19 cm (Figure 1). An abnormal cardiac anatomy was suspected, and the persistence of a left superior vena cava (incidence, ±0.2% to 0.4%; in patients with congenital heart disease, ±4%) was confirmed during surgery.
On a postoperative chest radiography (Figure 2) and computed tomography scan (Figure 3), the course of the catheters through the persistent left superior vena cava and the coronary sinus opening into the right atrium is visible. Figure 3 demonstrates 2 catheters in the coronary sinus. In general, a persistent left superior vena cava does not cause medical problems, but its existence may cause confusion during central venous access procedures or placement of pacemakers.