Impaired central hemodynamic response and exaggerated vasoconstriction during muscle metaboreflex activation in heart failure patients.
The muscle metaboreflex is enhanced in chronic heart failure (CHF) patients, and this fact has been associated with the early fatigue shown by these patients in response to exercise. In animal studies of CHF, it was found that the limited capacity to enhance ventricular performance is responsible for a functional shift from a cardiac output to a systemic vascular resistance (SVR) increase in the mechanism by which the cardiovascular system raises blood pressure in response to the metaboreflex. However, the existence of this functional shift is still unknown in humans. The present study was undertaken to test the hypothesis that a similar hemodynamic response was also present in humans with CHF. The hemodynamic response to metaboreflex activation obtained through postexercise ischemia was assessed in nine patients with CHF and nine healthy controls (CTL) by means of impedance cardiography. The main results were that 1) the blood pressure rise due to the metaboreflex was similar in the two groups; 2) the CTL group achieved the blood pressure response via cardiac output increase, and the CHF group, via SVR increase; and 3) stroke volume was enhanced in the CTL group and decreased in the CHF group. This study demonstrates that in CHF patients, metaboreflex recruitment causes a functional shift from flow increase to peripheral vasoconstriction in the mechanism through which blood pressure is increased. The incapacity to enhance cardiac performance and stroke volume is probably the primary cause of this cardiovascular alteration.
Crisafulli
Antonio
A
Department of Science Applied to Biological Systems, University of Cagliari, Via Porcell 4, 09124 Cagliari, Italy. crisafulli@tiscali.it
Salis
Enrico
E
Tocco
Filippo
F
Melis
Franco
F
Milia
Raffaele
R
Pittau
Gianluigi
G
Caria
Marcello A
MA
Solinas
Roberto
R
Meloni
Luigi
L
Pagliaro
Pasquale
P
Concu
Alberto
A
D001794:Blood Pressure; D002302:Cardiac Output; D002303:Cardiac Output, Low / Q000378:metabolism / Q000503:physiopathology*; D002307:Cardiography, Impedance; D016022:Case-Control Studies; D002908:Chronic Disease; D015444:Exercise; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000098:blood supply / Q000294:innervation / Q000378:metabolism*; D009200:Myocardial Contraction; D012018:Reflex; D012039:Regional Blood Flow; D012720:Severity of Illness Index; D013318:Stroke Volume; D014655:Vascular Resistance; D014661:Vasoconstriction; D016277:Ventricular Function, Left