CARDIOVASCULAR ENGINEERING Journal for Extracorporeal Circulation, Assist Devices,Transplantation and Artificial Organs
	Volume 2, 1997, No 3

Comparison of Three Indexes of Contractility in the Neonatal Left Ventricle

M. J. Davies, R. L. Quarterman, S. S. L. Tsui, M. T. Jacobs, J. W. Davis, M. J. Elliott, R. M. Ungerleider, J. W. Gaynor

Abstract:
Background: There are many differences between the neonatal and adult myocardium. Indices of contractile performance which are useful in the adult may not be applicable in the neonate. Thus, three indices commonly utilised in the adult (the stroke work-end diastolic volume relation, also termed the preload recruitable stroke work (PRSW) relation, the maximum dP/dt-end-diastolic volume (dP/dtmax-EDV ) relation, and the end-systolic pressure-volume (ESPV) relation), were compared in neonatal swine. Methods: Following autonomic blockade, twenty-nine one week old piglets were assessed under steady state conditions and during preload reduction by transient vena caval occlusion. Data were collected under control conditions and over a range of paced heart rates; under a range of physiological afterload conditions produced by infusions of phenylephrine and nitroprusside; after calcium infusion and following five minutes of global myocardial ischemia. Results: The dP/dtmax-EDV relation was more variable and thus less reproducible than the PRSW and ESPV relations. All three relations were linear, and insensitive to heart rate and afterload in the physiological range. The slope of the PRSW relation was the most sensitive to inotropic status, increasing 69 75% after calcium and falling 23 19% after ischemia (both p <0.05). in contrast, the slopes of the dp/dtmax-edv and espv relations did not change significantly despite changes in inotropic state (p > 0.05). conclusions: the prsw relation is the preferred index of contractile performance in the neonatal left ventricle. it is stable, relatively insensitive to afterload and heart rate, and yet it accurately measures changes in inotropic state. this would validate its use in perioperative clinical studies of myocardial contractility in the neonatal heart.

Keywords:
neonate, ventricular function, contractility, preload recruitable stroke work relation, dP/dtmax-end-diastolic volume relation, end-systolic pressure-volume relation

Address for Correspondence:

Reference:
(CVE. 1997; 2 (3): 180-190)

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