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.

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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