Complete heart block during central venous catheter placement in a patient with pre-existing left bundle branch block.

Heart block and arrhythmia are complications of pulmonary artery and cardiac catheterization. Injury to the conducting system of the heart often involves the right bundle causing right bundle branch block (RBBB). If patients already have left bundle branch block (LBBB), complete heart block (CHB) may result. After trauma, impairment of the right bundle is usually transient with recovery in hours, but complete heart block can lead to symptoms requiring invasive treatment. Similar complications are rare with insertion of central venous catheters, as they should not enter the heart. Injury to the right bundle during central venous catheter insertion can be by trauma from the guide wire or from the catheter itself. The function of the AV node and bundle of His in these patients has not been studied before. We report a patient with LBBB who developed CHB during insertion of a central venous cannula. Conduction through the AV node and His-Purkinje system was intact, showing that the transient RBBB was caused by traumatic injury rather than by other disease of the conduction system.

Torsades de pointes in 3 patients with leukemia treated with arsenic trioxide.

Arsenic trioxide is used in clinical trials in the treatment of relapsed and resistant cases of acute promyelocytic leukemia. Adverse effects from arsenic in these studies have been multisystemic. Arsenic is known to cause corrected QT-interval prolongation and T-wave changes, but the potential for serious ventricular arrhythmias is less well understood. Torsades de pointes, a form of ventricular tachycardia, has been reported with arsenic poisoning but not at therapeutic doses used in protocols for hematologic malignancies. We describe 3 patients in whom this arrhythmia developed while they were treated with arsenic trioxide. Early recognition of the arrhythmia or correction of contributory factors is important because arsenic induced ventricular arrhythmias are known to be resistant to most chemical methods and electrical cardioversion.