Dual chamber pacing with a single-lead DDD pacing system.
The successful application of single-lead VDD pacing during the last few years has generated the idea of single-lead DDD pacing. Preliminary data from several single-lead VDD studies attempting to pace the atrium by a floating atrial dipole are unsatisfactory, causing an unacceptably high current drain of the device. We studied the feasibility as well as the short- and long-term stability of atrioventricular sequential pacing, using a new single-pass, tined DDD lead. In eight consecutive patients (age 73+/-16 years) with symptomatic higher degree AV block and intact sinus node function, this new single-pass DDD lead was implanted in combination with a DDDR pacemaker. Correct VDD and DDD function was studied at implantation; at discharge; and at 1, 3, and 6 months of follow-up. At implant, the atrial stimulation threshold was 0.6+/-0.1 V/0.5 ms. During follow-up, the atrial pacing thresholds in different every day positions averaged 2.1+/-0.5 V at discharge, 2.9+/-0.5 V at 1 month, 3.8+/-0.4 V at 3 months, and 3.4+/-0.4 V at 6 months (pulse width always 0.5 ms). The measured P wave amplitude at implantation was 4.5+/-2.2 mV; during follow-up the telemetered atrial sensitivity thresholds averaged 2.1+/-0.3 mV. Phrenic nerve stimulation at high output pacing (5.0 V/0.5 ms) was observed in three (38%) patients at discharge and in one (13%) patient during follow-up; an intermittent unmeasurable atrial lead impedance at 3 and 6 months follow-up was documented in one (13%) patient. This study confirms the possibility of short- and long-term DDD pacing using a single-pass DDD lead. Since atrial stimulation thresholds are still relatively high compared to conventional dual-lead DDD pacing, further improvements of the atrial electrodes are desirable, enabling lower pacing thresholds and optimizing energy requirements as well as minimizing the potential disadvantage of phrenic nerve stimulation.
Naegeli
B
B
Cardiac Unit, Department of Internal Medicine, Stadtspital Triemli, Zürich, Switzerland.
Straumann
E
E
Gerber
A
A
Schuiki
E
E
Kunz
M
M
Niederhäuser
U
U
Bertel
O
O
D000368:Aged; D000369:Aged, 80 and over; D001283:Atrioventricular Node / Q000503:physiopathology; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006327:Heart Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial