Cardiodynamic and neurohormonal importance of atrial contribution in rate-responsive pacing

• Published in: The American journal of cardiology Vol. 72; no. 1; pp. 36 - 40
• Main Authors: Seino, Yoshihiko, Shimai, Shinichiro, Nagae, Yasuhiro, Ibuki, Chikao, Takano, Teruo, Tanaka, Shigeo, Hayakawa, Hirokazu
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-07-1993; Elsevier; Elsevier Limited
• Subjects: Aged; Atrial Function; Atrial Natriuretic Factor - blood; Biological and medical sciences; Cardiac dysrhythmias; Cardiac Pacing, Artificial - methods; Cardiology. Vascular system; Circulatory system; Cyclic AMP - blood; Cyclic GMP - blood; Epinephrine - blood; Equipment Design; Exercise; Female; Heart; Hormones; Humans; Male; Medical research; Medical sciences; Middle Aged; Norepinephrine - blood; Pacemaker, Artificial; Sick Sinus Syndrome - blood; Sick Sinus Syndrome - physiopathology; Sick Sinus Syndrome - therapy; Ventricular Function, Left; Physical exercise; Human; Atrium; Arrhythmia; Synchronism; Instrumentation therapy; Cardiovascular disease; Heart ventricle; Catecholamine; Excitability disorder; Sick sinus syndrome; Instrumental stimulation; Pacemaker; Heart disease; Norepinephrine; Hormonal investigation; Left ventricle performance
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/0002-9149(93)90215-X

To elucidate the physiologic importance of atrial contribution in recently developed rate-responsive pacing, changes in cardiodynamics and neurohormonal factors were analyzed during exercise in patients with respiratory rate-dependent, rate-responsive atrial (AAIR; n = 6) and ventricular (VVIR; n = 9) demand mode pacemakers implanted for sick sinus syndrome. With increasing pacing rate during bicycle ergometer exercise, the AAIR group had significant increases in cardiac index (p < 0.05), left ventricular ejection fraction (p < 0.05), and ejection (p < 0.05) and peak filling (p < 0.05) rates; however, the VVIR group had a significant decrease in ejection fraction (p < 0.05), and an increase in cardiac index (p < 0.05) that was significantly less than in the AAIR group. At rest, the mean plasma concentrations of atrial natriuretic peptide (p < 0.005) and cyclic guanosine monophosphate (p < 0.05) were significantly greater in the VVIR group than in the AAIR group and normal subjects (n = 8). Atrial natriuretic peptide, norepinephrine, and cyclic adenosine and guanosine monophosphates were significantly greater (p < 0.05) during exercise, and atrial natriuretic peptide was significantly greater in the VVIR group (207.5 ± 8.3 pg/ml) than in the AAIR group (116.4 ± 51.5) and normal subjects (30.8 ± 19.2; p < 0.05); this suggested a further increase in the nonphysiologic atrial overload with VVIR pacing. The data show both the neurohormonal and cardiodynamic importance of atrioventricular synchrony in rate-responsive pacing.