Discussion
Cardiac pacemakers and defibrillators are cornerstones in the management
of patients with heart rate and/or rhythm problems. There is a steady
growth in the use of pacemaker and defibrillator therapy in the United
States and across the world (1-3). Although commonly inserted with
access through the left subclavian or cephalic vein, inadvertent entry
through the subclavian artery can lead to iatrogenic complications,
including thromboembolism. Quick diagnosis of this event is essential,
as leaving the lead is associated with an increased risk of
life-threatening thromboembolism. Thrombus formation on the lead can
occur within days, and fibrous tissue may begin developing in just a few
months (4).
There are several methods available to avoid the occurrence of such
events. When subclavian vein puncture is attempted, the subclavian
artery may also be punctured. Arteriography may be used to identify the
accessed vessel. In addition, successful venipuncture may be observed as
the guidewire advances into the inferior vena cava under fluoroscopy. If
there are ventricular premature beats with right bundle branch block
pattern soon after the guidewire enters the ventricular cavity, the
possibility of the guidewire entering through the artery must be
considered. After the pacemaker is implanted, correct positioning of the
pacemaker may also be seen through ECG. Right ventricular pacing is
indicated when ECG shows left bundle branch block appearance, while left
ventricular pacing is seen in right bundle branch block patterns (5).
Removal of the lead is one solution to avoid thromboembolic events but
comes with other complications. Extraction of transarterially placed
leads is associated with high thromboembolic risk as well as risk of
bleeding from the arterial entry site. Furthermore, lead removal can
lead to ventricular perforation or cardiac tamponade, and may cause
trauma to the aorta, aortic valve, and coronary arteries (6). Given the
direct connection to systemic circulation, any lead manipulation can
potentially lead to systemic embolization. Due to the unnecessary risks
pertaining to surgical removal, conservative management with lifelong
anticoagulation may be an acceptable alternative in chronically
implanted left ventricular cavity leads.