Process for measuring the cardiac volume

Details Process for measuring the cardiac volume Process for measuring the cardiac volume

1980-03-27

1982-04-27

Michell, Robert W.

Surgery

Truss

Pad

364415, 73204, A61D 502

Patent

active

043265391

ABSTRACT:
The invention relates to a process for the measurement of cardiac volumes of the beating heart, in pulsed flow conditions, by means of a tracer injected upstream of or in the ventricle at a controlled injection flow D.sub.i during a controlled injection time t.sub.i. The variation of concentration .DELTA. of the tracer with respect to time, in a pulsed flow regime varies in a steplike manner, the concentration at each cardiac cycle n being .DELTA.n.
According to the invention, after acquiring the concentration .DELTA. of the tracer during a number N of complete cardiac periods and computing the step concentration .DELTA.n, the mean cardiac period .tau. from the number of recorded cardiac cycling intervals n, the following summated concentration products can be formed: ##EQU1## where m is any cycle corresponding to or occurring after the M.sup.th cardiac cycle but before the N.sup.th cycle (M.ltoreq.m<N), where M is the cycle at which at maximum step concentration of tracer occurs, where N is a conveniently great number of cycles encompassing the measurement process and where 1 is the cardiac cycle corresponding to the first step of the tracer curve, where .tau.(l;N) is the mean cardiac period over N cardiac cycles, and .tau.(m;N) is the mean cardiac period over the (N-(m-l)) cardiac cycles, whence the cardiac volumes are determined from the measured values (.DELTA..sub.n, .tau..sub.n) and from the aforementioned relationships (S, S').

REFERENCES:
patent: 4035622 (1977-07-01), Obermajer
patent: 4137910 (1979-02-01), Murphy
Ellis, R. J. et al., "Computerized Monitoring of Cardiac Output by Thermal Dilution," Jourl. Assn. Adv. Med. Instrum. v. 6#2, Mar.-Apr. 1972 pp. 116-121.

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