The A‐R Interval as Exercise Indicator: A New Option for Rate Adaptation in Single and Dual Chamber Pacing

Abstract

We investigated the possibility to use the interval from an atrial stimulus to the ventricular R wave (A-R interval) as an indicator of physical stress, in 16 patients with pacemakers implanted for severe atrial bradycardia but with intact AV conduction. The A-R interval was studied during incremental atrial pacing at rest and during exercise with a constant workload. In addition, the atrial pacing rate was kept constant just above spontaneous sinus rate and the dynamics of the A-R interval were studied during exercise with a low constant workload and during a maximal exercise test with increasing workload. Incremental atrial pacing prolonged the A-R interval and this response was blunted during exercise (P less than 0.003). Atrial pacing at a constant rate and during a constant workload resulted in an almost direct shortening of the A-R interval. When the workload was increased but the atrial rate kept constant, a pronounced shortening of the A-R interval was noted (P less than 0.0001). It is concluded that changes of the A-R interval during different kinds of exercise were prompt and predictable in patients with sinus node dysfunction but intact AV conduction. In these patients the shortening of the A-R interval during exercise may be a suitable indicator for rate adaptive atrial pacing.

Sensorgesteuerte Herzschrittmacher-Systeme

“…Im Kreislauf lassen sich funktionell und morphologisch Arterien (elastisches Hochdrucksystem), Arteriolen (Widerstandsgefäße), Kapillaren (Gas-und Stoffaustausch), Venolen und Venen (Niederdrucksystem) unterscheiden. 516 at -Automatisierungstechnik 46 (1998) 11 Bereits realisierte oder in der Entwicklung befindliche Systeme nutzen andere physiologische Sensorsignale und nähern sich vom systemtechnischen Konzept her in sehr unterschiedlicher Weise der Zielsetzung, die ursprüngliche physiologische Regelung wiederherzustellen (Bild 6). Es lassen sich im wesentlichen folgende Kategorien unterscheiden: Steuerung (Open-loop-Systeme), geschlossene Systeme durch Nutzung der Kopplung der Herz/Kreislauf-Regulation mit anderen physiologischen Systemen (wobei die Kopplung teilweise so schwach ist, daß der Übergang in offene Systeme fließend ist) und Regelungen mit Hilfe "inotroper" oder "dromotroper" Schrittmacher, die durch Si- …”

“…Diese Tatsache führte zu der Überlegung, die AV-Überleitungszeit durch einen Zwei-Kammer-Schrittmacher zu messen und als Steuersignal für einen "dromotropen" Schrittmacher (vgl. Bild 8) zu nutzen, der dem Ideal des "chronotropen" Schrittmachers sehr nahe käme, da er den eingetretenen SSS-Block ebenfalls durch Überbrückung kompensieren würde [10][11][12].…”

Rate-responsive pacing using the atrio-ventricular conduction time: Design and test of a new algorithm

“…Provided that the atrio-ventrictflar conduction is regular and there is no atrial fibrillation, AVCT can be used for heart rate control in an implanted pacemaker, and it can be assumed that the original physiological control loop can be restored to a great extent. Consequently, it was proposed that this sensor was used for rateresponsive pacing (IRN~CH and CONP, ADY, 1986;IRNICH, 1988;BAKER, 1989;RUITER et al, 1990;STOOP and BEGEMANN, 1994).…”