Stiffness of the distal tip of bipolar pacing leads.
The stiffness of a bipolar pacing lead, particularly between anode and cathode, may be responsible for myocardial penetration and perforation. Following an unprecedented 7% incidence of high threshold exit block with a single model bipolar ventricular endocardial lead, a study was undertaken to compare pacing lead stiffness between anode and cathode of six models of bipolar leads from two manufacturers; Telectronics (T) and Medtronics (M). Four leads had polyurethane insulation; T 030-284 (Laser Dish), T 329-259 (Cordis, Encor), M 4012 (Target Tip), and M 4004 (Capsure). Two leads had silicone rubber insulation; M 5026 (Capsure) and M 5024 (Capsure SP). All leads were subjected to two stiffness tests. The Tip Deflection Test involved securing the lead at 45 degrees at the indifferent electrode and applying a force to deflect the tip 5 mm. The three point bending test involved placing the lead over two fixed bars in contact with the anode and cathode. Midway a third bar was pushed onto the lead and the force to deflect the lead 2 mm was recorded. The results showed that pacing leads with polyurethane insulation were much stiffer than those with silicone rubber insulation. The T 030-284 because of its construction was found to be the stiffnest. The next stiffnest was the M 4012. Both these leads had an unacceptable incidence of high threshold exit block; 7% with the T 030-284 (89 implants) and 3% with the M 4012 (102 implants). No cases of high threshold exit block were documented with the other four pacing leads and in particular the silicone rubber M 5026 (344 implants).(ABSTRACT TRUNCATED AT 250 WORDS)
Cameron
J
J
Commonwealth Dept. of Community Services and Health, Royal Melbourne Hospital, Victoria, Australia.
Mond
H
H
Ciddor
G
G
Harper
K
K
McKie
J
J
D002304:Cardiac Pacing, Artificial / Q000009:adverse effects; D004548:Elasticity; D004567:Electrodes, Implanted; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D010138:Pacemaker, Artificial; D011140:Polyurethanes / Q000737:chemistry; D012189:Retrospective Studies; D012826:Silicone Elastomers / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
D011140:Polyurethanes; D012826:Silicone Elastomers