Introduction: Atrial tachycardia and chronic heart failure (CHF) are associated with elevated levels of atrial natriuretic peptide (ANP) and its amino terminal part NT-ANP. Chronic high atrial rates may cause CHF due to a rapid ventricular response. The aim of this study was to establish the contribution of elevated atrial rate and of high ventricular rate, resulting in CHF, on ANP and NT-ANP levels during chronic atrial tachycardia. Methods and Results: Thirteen goats (AV-paced group) were subjected to 4 weeks of rapid AV pacing with an atrial and ventricular rate of 240 beats/min. Another five goats (A-paced group) were subjected to 4 weeks of atrial pacing at 240 beats/inin while the ventricular rate was kept low and regular at 80 beats/min. Pacing was interrupted only for measurement of right atrial (RA) and left ventricular (LV) diameter and sampling for ANP, NT-ANP, and renin. In the AV-paced group, RA and LV diameter reached 152% and 109% of baseline values, respectively. Both ANP and NT-ANP (8.3 ± 9.2 pmol/L and 0.5 ± 0.4 nmol/L at baseline, respectively) increased progressively (53.1 ± 37.9 pmol/L and 2.0 ± 0.9 nmol/L, respectively, after 4 weeks). There was a significant correlation between the magnitude of atrial dilation and natriuretic peptide levels after 3 days. In A-paced goats, however, RA and LV diameters did not change. Furthermore, ANP and NT-ANP levels (9.1 ± 6.0 pmol/L and 0.8 ± 0.2 nmol/L at baseline, respectively) were unchanged after 4 weeks (5.3 ± 3.4 pmol/L and 0.6 ± 0.2 nmol/L, respectively). Conclusion: Elevated levels of ANPs during chronic atrial tachycardia are related to a high ventricular rate rather than a high atrial rate alone. Rather than atrial tachycardia, the atrial hemodynamic burden is an important determinant of the sustained ANP response.

Fibrillation, Heart failure, Natriuretic peptides, Pacing,
Journal of Cardiovascular Electrophysiology
Department of Internal Medicine

Schoonderwoerd, B.A, Crijns, H.J, van Veldhuisen, D.J, Boomsma, F, van den Berg, M.P, Bel, K.J, & van Gelder, I.C. (2004). Atrial natriuretic peptides during experimental atrial tachycardia: Role of developing tachycardiomyopathy. Journal of Cardiovascular Electrophysiology, 15(8), 927–932. doi:10.1046/j.1540-8167.2004.04093.x