Multicenter experiences with a single lead electrode for dual chamber ICD systems

Monitoring of atrial signals improves the accuracy in identifying supravent ricular tachyarrhythmias to prevent inappropriate therapies in patients wit h implantable ICDs. Since difficulties due to the additional atrial lead we re found in dual chamber ICD systems with two leads, the authors designed a single pass VDD lead for use with dual chamber ICDs. After a successful an imal study, the prototype VDD lead (single coil defibrillation lead with tw o additional fractally coated rings for bipolar sensing in the atrium) was temporarily used in 30 patients during a German multicenter study. Atrial a nd ventricular signals were recorded during sinus rhythm (SR), atrial flutt er, AF, and VT or VF. The implantation of the lead was successful in 27 of 30 patients. Mean atrial pacing threshold was 2.5 +/- 0.9 V/0.5 ms, mean at rial impedance was 213 +/- 31 Omega. Atrial amplitudes were greater during SR (2.7 +/- 1.6 mV) than during atrial flutter (1.46 +/- 0.3 mV, P < 0.05) or AF (0.93 +/- 0.37 mV, P < 0.01). During VF atrial "sinus" signals had si gnificantly (P < 0.01) lower amplitudes (1.4 <plus/minus> 0.52 mV) than dur ing SR. The mean ventricular sensing was 13.3 +/- 7.9 mV and mean ventricul ar impedance was 577 +/- 64 Omega. Defibrillation was successful with a 20- J shock in all patients. In addition, 99.6% of P waves could be detected in SR and 84.4% of flutter waves during atrial flutter. During AF, 56.6% of a trial signals could be detected without modification of the signal amplifie r. In conclusion, a new designed VDD dual chamber lead provides stable dete ction of atrial and ventricular signals during SR and atrial flutter. Relia ble detection of atrial signals is possible without modification of the ICD amplifier.