Noninvasive measurement of retrograde conduction times in pacemaker patients.
Retrograde, or ventriculoatrial conduction (VAC) has been measured in 67% of pacemaker patients with SSS and 25% of patients with 3 degrees block. DDD pacers use the postventricular atrial refractory period (PVARP) to prevent sensing VAC. If the PVARP is too short, a pacer-mediated tachycardia (PMT) could occur. If too long, rapid atrial rates may not be sensed. To accurately set the PVARP, VAC must be measured. Five noninvasive methods are described: (1) Surface ECG during VVI pacing; (2) Atrial intracardiac electrograms during VVI pacing; (3) Initiating a PMT with long pacemaker AV interval; (4) Initiating a PMT at the maximum tracking rate; (5) DDI mode with electronic calipers. The description of these methods is intended to enable a physician to detect and measure VAC in patients with any manufacturer's DDD or VDD pacemaker.
Marco
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Siemens-Pacesetter, Inc., Sylmar, CA.
Gallagher
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D002304:Cardiac Pacing, Artificial / Q000379:methods; D004562:Electrocardiography; D006327:Heart Block / Q000628:therapy; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000628:therapy; D013997:Time Factors