ISSN:
1741-0444
Keywords:
Cardiac energetics
;
Coronary sinus flow
;
Error analysis
;
Left ventricular mechanical efficiency
;
Thermodilution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract A system to measure left ventricular heat productionΦ Iv in conscious human subjects is described. UsingΦ Iv and the rate of energy supply to the myocardium, the mechanical efficiency of the left ventricle is calculated. Heat carriage in left ventricular myocardial blood flowΦ CS is calculated from coronary sinus flow and the transcoronary temperature difference. Diffusional heat lossΦ diff is derived from the ratio of areas under temperature/time curves recorded in the aorta and coronary sinus after a bolus injection of cold saline into the pulmonary artery. The sum ofΦ cs andΦ diff (the energy of endothermic reactions with haemoglobin) givesΦ Iv . The estimated errors in the derived values of heat production and mechanical efficiency are less than 17 per cent. At basal heart rates 17 patients with good left ventricular function had a transcoronary temperature difference of 0·16±0·03°C (mean ± standard deviation), left ventricular flow blood flow of 145·3±81·5 ml min−1, andΦ Iv of 3·1±1·8 W. Left ventricular oxygen extraction was strongly correlated withΦ Iv (r=0.925, p〈0·001). Left ventricular mechanical efficiency was 0·33±0·11, at basal heart rates, which fell to 0·18±0·15 (p〈0·001) on atrial pacing at 100 beats min−1.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02447100
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