Atrial natriuretic peptides during experimental atrial tachycardia: role of developing tachycardiomyopathy.
BACKGROUND
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.


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/min 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).


CONCLUSIONS
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.
Schoonderwoerd
Bas A
BA
Department of Cardiology, Thoraxcenter, University Hospital Groningen, Groningen, The Netherlands. B.A.Schoonderwoerd@thorax.azg.nl
Crijns
Harry J G M
HJ
van Veldhuisen
Dirk J
DJ
Boomsma
Frans
F
van den Berg
Maarten P
MP
Bel
Klaas J
KJ
van Gelder
Isabelle C
IC
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood*; D005260:Female; D006041:Goats; D006333:Heart Failure / Q000097:blood* / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D013612:Tachycardia, Ectopic Atrial / Q000097:blood* / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D017180:Tachycardia, Ventricular / Q000097:blood* / Q000150:complications / Q000503:physiopathology*
D009320:Atrial Natriuretic Factor