[en] OBJECTIVE: The aim of this study was to investigate left ventricular contractility and energetic cost of cardiac ejection under conditions of acute increase in aortic compliance. METHODS: In six anaesthetized pigs, ascending aortic compliance was increased by adding a volume chamber in parallel to the ascending aorta. Systemic vascular parameters, including characteristic impedance, peripheral resistance, total vascular compliance, and inertance, were estimated with a four-element windkessel model. Arterial elastance was derived from these parameters. Left ventricular systolic function was assessed by end-systolic pressure-volume relationship (end-systolic elastance), and stroke work. Pressure-volume area was used as a measure of myocardial oxygen consumption. Heart rate remained constant during the experimentation. RESULTS: Adding the aortic volume chamber significantly increased vascular compliance from 0. 95+/-0.08 to 1.17+/-0.06 ml/mmHg (P<0.01), while inductance, characteristic impedance, peripheral resistance, and arterial elastance remained statistically at basal values, respectively 0. 0020+/-0.0003 mmHg.s(2)/ml, 0.105+/-0.009 mmHg.s/ml, 1.27+/-0.12 mmHg.s/ml, and 2.43+/-0.21 mmHg/ml. During the same interval, stroke work and pressure-volume area decreased respectively from 2700+/-242 to 2256+/-75 mmHg.ml (P<0.01), and from 3806+/-427 to 3179+/-167 mmHg.ml (P<0.01). Stroke work and pressure-volume area decreased at matched end-diastolic volumes. In contrast, end-systolic elastance, ejection fraction, and stroke volume remained statistically unchanged, respectively at 2.29+/-0.14 mmHg/ml, 48.1+/-2.1 %, and 32. 4+/-1.7 ml. CONCLUSIONS: These data suggest that, when facing an increased aortic compliance, the left ventricle displays unchanged contractility, but the energetic cost of cardiac ejection is significantly decreased. These data may be of clinical importance when choosing an artificial prosthesis for ascending aortic replacement.
Disciplines :
Cardiovascular & respiratory systems
Author, co-author :
Kolh, Philippe ; Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Service de biochimie et de physiologie humaines, normale et pathologique
D'Orio, Vincenzo ; Université de Liège - ULiège > Département des sciences cliniques > Médecine d'urgence - bioch. et phys. hum. normales et path.
Lambermont, Bernard ; Centre Hospitalier Universitaire de Liège - CHU > Frais communs médecine
Gérard, Paul ; Université de Liège - ULiège > Département de mathématique > Statistique (aspects expérimentaux)
Gommes, Cédric ; Université de Liège - ULiège > Département de chimie appliquée > Génie chimique - Génie catalytique
Limet, Raymond ; Université de Liège - ULiège > Département des sciences cliniques > Chirurgie cardio-vasculaire et thoracique
Language :
English
Title :
Increased Aortic Compliance Maintains Left Ventricular Performance at Lower Energetic Cost
Sunagawa K., Maughan W.L., Sagawa K. Optimal arterial resistance for the maximal stroke work studied in isolated canine left ventricle. Circ Res. 56:1985;586-595.
Kelly R.P., Tunin R., Kass D.A. Effect of reduced aortic compliance on cardiac efficiency and contractile function of in situ canine left ventricle. Circ Res. 71:1992;490-502.
Randall O., Van Den Bos G., Westerhof N. Systemic compliance: Does it play a role in the genesis of essential hypertension? Cardiovasc Res. 18:1984;455-462.
Burkhoff D., De Tombe P.P., Hunter W.C., Kass D.A. Contractile strength and mechanical efficiency of left ventricle are enhanced by physiological afterload. Am J Physiol. 260:1991;H569-H578.
Baan J., van der Velde E.T., De Bruin H.G., Smeenk G., Koops J., van Dijk A., Temmerman D., Senden J., Buis B. Continuous measurement of left ventricular volume in animals and humans by conductance catheter. Circulation. 70:1984;812-823.
Steendijk P., van der Velde E.T., Baan J. Left ventricular stroke volume by single and dual excitation of conductance catheter in dogs. Am J Physiol. 264:1993;H2198-H2207.
Baan J., van der Velde E.T. Sensitivity of left ventricular end-systolic pressure-volume relation to type of loading intervention in dogs. Circ Res. 62:1988;1247-1258.
Suga H., Kitabatake A., Sagawa K. End-systolic pressure determines stroke volume from fixed end-diastolic volume in the isolated canine left ventricle under a constant contractile state. Circ Res. 44:1979;238-249.
Sagawa K., Maughan L., Suga H., Sunagawa K. Cardiac contraction and the pressure-volume relationship. 1988;Oxford University Press, New York.
Suga H. External mechanical work from relaxing ventricle. Am J Physiol. 236:1979;H494-H497.
Suga H. Total mechanical energy of a ventricle model and cardiac oxygen consumption. Am J Physiol. 236:1979;H498-H505.
Denslow S. Relationship between PVA and myocardial oxygen consumption can be derived from thermodynamics. Am J Physiol. 270:1996;H730-H740.
Westerhof N., Elzinga G., Sipkema P. An artificial arterial system for pumping hearts. J Appl Physiol. 31:1971;776-781.
Grant B., Paradowski L. Characterization of pulmonary arterial input impedance with lumped parameter models. Am J Physiol. 252:1987;H585-H593.
Lambermont B., Kolh P., Detry O., Gerard P., Marcelle R., D'Orio V. Analysis of endotoxin effects on the intact pulmonary circulation. Cardiovasc Res. 41:1999;275-281.
Winer B.J. Statistical principles in experimental design. 1971;McGraw-Hill, New York.
O'Rourke M.F. Arterial function in health and disease. 1982;Churchill and Livingstone, Edinburgh.
Yin F., Liu Z. Arterial compliance-physiological viewpoint. Westerhof N., Gross D.R. Vascular dynamics: physiological perspectives. 1989;9-22 Plenum, New York.
Elzinga G., Westerhof N. Pressure and flow generated by the left ventricle against different impedances. Circ Res. 32:1973;178-186.
Sunagawa K., Maughan W.L., Sagawa K. Stroke volume effect of changing arterial input impedance over selected frequency ranges. Am J Physiol. 248:1985;H477-H484.
