Citations

BACKGROUND Recent studies have reported that asymptomatic left ventricular dysfunction (ALVD) in humans is characterized by early neurohumoral activation. Specifically, atrial natriuretic factor (ANF) and norepinephrine are activated without activation of the renin-angiotensin-aldosterone system (RAAS). The current study describes hemodynamic and renal function associated with this neurohumoral profile in a canine model of early and presumably "asymptomatic" ventricular dysfunction. We hypothesized that the neurohumoral profile observed in ALVD is associated with preservation of renal function despite significant hemodynamic compromise. METHODS AND RESULTS ALVD was produced by ventricular pacing at 180 beats per minute for 10 days. Intravascular volume expansion was performed before and after producing ALVD in eight conscious dogs. The model of ALVD was characterized by decreases in ejection fraction (48 +/- 2 to 29 +/- 4%), cardiac output (4.64 +/- 0.29 to 2.89 +/- 0.17 L/min), and mean arterial pressure (119 +/- 4 to 108 +/- 4 mm Hg). Atrial pressures and systemic vascular resistance were increased. ANF (60 +/- 19 to 165 +/- 27 pg/mL) and norepinephrine (382 +/- 127 to 690 +/- 211 pg/mL) were activated, whereas the RAAS was not. Creatinine clearance and sodium excretion (UNa V) were unchanged after producing ALVD. The natriuretic response to volume expansion in ALVD was completely intact, with increases in UNa V similar to that observed with volume expansion in ALVD was completely intact, with increases in UNa V similar to that observed with volume expansion before producing ALVD. CONCLUSIONS The current study demonstrates that significant ventricular dysfunction with peripheral vasoconstriction can be associated with normal renal function and thus suggests an important functional role for the neurohumoral profile of ALVD in preserving sodium balance.

Background— After acute myocardial infarction (AMI), diastolic function assessed by Doppler echocardiography provides important prognostic information that is incremental to systolic function. However, Doppler variables are affected by multiple factors and may change rapidly. In contrast, left atrial (LA) volume is less influenced by acute changes and reflects subacute or chronic diastolic function. This may be of importance when one assesses risk in patients with AMI. Methods and Results— Three hundred fourteen patients with AMI who had a transthoracic echocardiogram with assessment of left ventricular (LV) systolic and diastolic function and measurement of LA volume during admission were identified. The LA volume was corrected for body surface area, and the population was divided according to LA volume index of 32 mL/m 2 (2 SDs above normal). LA volume index was >32 mL/m 2 in 142 (45%). The primary study end point was all-cause mortality. During follow-up of 15 (range 0 to 33) months, 46 patients (15%) died. LA volume index was a powerful predictor of mortality and remained an independent predictor (hazard ratio 1.05 per 1-mL/m 2 change, 95% CI 1.03 to 1.06, P <0.001) after adjustment for clinical factors, LV systolic function, and Doppler-derived parameters of diastolic function. Conclusions— Increased LA volume index is a powerful predictor of mortality after AMI and provides prognostic information incremental to clinical data and conventional measures of LV systolic and diastolic function.