Papillary muscle rupture of the mitral valve complicating removal of a permanent transvenous electrode

Extraction of implanted transvenous pacing leads: a review of a persistent clinical problem

Within a few months of implantation, permanent pacemaker leads become ensheathed in fibrocollagenous tissue. This tissue may anchor the lead so that it is difficult, dangerous, or impossible to remove it. Leads with bulbous or finned tips are particularly resistant to extraction. The risks of applying traction to an entrapped lead include induction of bradycardia or ventricular tachycardia and fibrillation, invagination of the right ventricle, avulsion of the right ventricular myocardium or tricuspid valve, hemopericardium, and cardiac tamponade. Forceful traction may result in uncoiling of the conductor, disruption of the insulation, or complete fracture, leaving an intravascular remnant that may embolize or be a source for thrombosis. Although fixation and abandonment of an inactive chronically implanted lead is frequently appropriate and is known to pose little long-term risk, the retained inactive lead may interact adversely with a new active lead and then increase the risk of venous thrombosis, serve as a potential nidus for infection, or produce spurious electrical sensing signals that may be sensed by the pulse generator. Absolute indications for lead removal are those in which there would be a life-threatening situation if the lead were to remain in situ. In the absence of an absolute indication, the decision to proceed with extraction must be made by weighing the potential for serious morbidity or mortality against risks of the extraction technique. Techniques for lead removal include traction and open cardiotomy operations. When a portion of the lead is intravascular, forceps, snares, baskets, countertraction, or lead-transection devices may be used to retrieve the fragment.

Cardiac pathology of transvenous pacemakers in dogs

Transvenous right ventricular pacemaker catheters were implanted in 18 mongrel dogs for periods of 2 to 18 months (average 4.9 months). Heart block was produced in 15 of these dogs by injection of 37 per cent formaldehyde into the interatrial septum. In the other three dogs which served as controls, no heart block was produced and no electrical stimulation was applied to the implanted catheters. After the animals had been put to death, gross and microscopic examination of the hearts revealed four categories of morphological changes: (1) connective tissue sheath formation around the catheters, (2) endocardial papillary thickening, (3) interatrial septal changes, and (4) myocardial damage. Changes 1, 2, and 4 occurred in one or more intracardiac locations in all 18 dogs. Change 3 occurred only in the 15 dogs in which heart block was produced. The most striking histologic findings were areas of cartilagenous metaplasia in endocardium an underlying myocardium and areas of marked cellular proliferation of the endocardial cells both in the endothelium and underlying stroma. Chronic implantation of transvenous intracardiac pacemaker catheters in dogs consistently produces morphologic changes which may interfere with cardiac and pacemaker function and may hinder attempts to remove nonfunctional or unneeded catheter electrodes. The changes observed appear to be related to the presence of foreign material per se and not external electrical stimulation of the heart.

Myocardial perforation by flexible Elema endocardial pacing catheters

Hurwitz, B. J., Zion, M. M., and Promund Obel, I. W. (1974).Thorax, 29, 678-684. Myocardial perforation by flexible Elema endocardial pacing catheters. Myocardial perforation as a complication of permanent endocardial pacing with flexible Elema catheters is described in nine patients. In eight patients pacing failed, but there were no other serious ill-effects. Diaphragmatic pacing occurred in five patients. Radiological evidence of movement, either posteriorly and/or laterally, of the electrode tip was detected in five patients. In only two of them was the electrode seen to be definitely extracardiac in position. A change in the pacing wave form aided the diagnosis in two patients. In a further two patients electrode tip electrocardiograms helped to confirm the diagnosis where, upon withdrawal of the perforating electrode, small Q waves disappeared, RS complexes enlarged, and the ST segments became more elevated, with deeply inverted T waves.

Withdrawal and repositioning of the electrode catheters was performed in seven patients. In one, a new catheter was inserted, and in another, where uninterrupted cardiac pacing was accompanied by intermittent diaphragmatic pacing, the pacing system was left unaltered. The follow-up is from six months to four and a half years with one late death apparently unrelated to pacing failure.