Assessment of Pacemaker Chronotropic Response: Implementation of the Wilkoff Mathematical Model

Abstract

There are few practical guidelines for proper adjustment of rate responsive pacemaker sensor parameters. This study describes the application of the chronotropic assessment exercise protocol (CAEP) and the Wilkoff model of chronotropic response to assess the adjustment of pacemaker sensor parameters. In 31 patients implanted 1 month previously with a dual sensor pacemaker, pacemaker sensor parameters were adjusted to yield a peak sensor rate of 100 beats/min on a simple 6-minute walk (low intensity treadmill exercise [LITE] protocol); the maximum sensor rate was set to the age predicted maximum heart rate (220-age). The rate response behavior of the pacemaker was then assessed using the slope of metabolic-chronotropic relation (MCR) during CAEP exercise. After adjustments based on the LITE protocol, CAEP exercise yielded MCR slopes of 0.92 +/- 0.25 for the entire study group, which compares well with the predicted normal slope of 1. However, 7 of the 31 patients had sensor MCR slopes during CAEP exercise that were 2 SD or more below expected. To test the sensitivity of this approach to suboptimal pacemaker programming or suboptimal exercise, simulations were performed with the maximum sensor rate programmed below age-predicted maximum heart rate or with exercise truncated before maximum exertion; with these conditions, MCR slopes were sharply lower for the entire group. The authors conclude that a simple treadmill walk (LITE) allowed for optimum programming of sensor parameters in most patients, but in a minority the chronotropic behavior was underresponsive. Failure to appropriately adjust pacemaker maximum sensor rate or failure to achieve peak exercise sharply limits the accuracy of this methodology.

Chronotropic incompetence and its relation to exercise intolerance in hypertrophic cardiomyopathy

“…Rateresponsive pacing has been shown to enhance functional capacity in patients with chronic heart failure and an inadequate chronotropic response, and in those meeting the definition of chronotropic incompetence [40,41]. There is no data to suggest that directly intervening on heart rate would improve exercise capacity in HCM.…”

The Incremental Benefit of Rate-Adaptive Pacing on Exercise Performance During Cardiac Resynchronization Therapy

“…Within four weeks before the study, all patients underwent a trial cardiopulmonary exercise test using DDD-OFF mode to familiarize them with the equipment. All patients then underwent symptom-limited cardiopulmonary exercise test on a treadmill (Q5000, Quinton, Seattle, Washington) using the chronotropic assessment exercise protocol (14). During the test, patients inspired room air through a low-resistance mask, and the expired O 2 and CO 2 partial pressures were measured with a gas analyzer (Cardiopulmonary Exercise Testing System, MedGraphics, St. Paul, Minnesota).…”

The Restoration of Chronotropic CompEtence in Heart Failure PatientS with Normal Ejection FracTion (RESET) Study: Rationale and Design

“…In this sense, the recent evidence in HFpEF patients of a similar correlation between HR response and exercise capacity is less surprising. Rate modulation or rate-adaptive pacing (RAP) via an implanted cardiac pacemaker can benefit patients with impaired chronotropic responses 24-26. However, whether or not RAP employed in HFpEF patients with chronotropic insufficiency would prove beneficial is unknown.…”