Process for measuring the cardiac volume

Claim 2

A process for the measurement of cardiac volumes of the beating heart, in pulsed flow conditions by dilution of a quantity Q i of tracer injected upstream of a ventricle, at controlled injection flow D i and during a controlled time t i comprising the steps of: recording the stepwise tracer concentration Δ n during a number N of complete cardiac periods n, by means of a transducer downstream of the injection site; and determining the cycle M at which maximum step concentration value Δ M occurs, as well as the mean cardiac cycling intervals, i.e. the cardiac period τ n , whereby forming the following summation products: ##EQU13## where m is any cycle corresponding to or occurring after the M th cardiac cycle but before the N th cycle (M≦m<N), where M is the cycle at which the maximum step concentration value Δ M 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 τ(1;N) is the mean cardiac period over N cardiac cycles ##EQU14## and τ(m;N) is the mean cardiac period over the (N-(m-1)) cardiac cycles ##EQU15## thereby determining the cardiac volumes are determined from the measured values (Δ n , τ n ) and from the aforementioned relationships (S,S').

Claim 3

A process according to claim 1, further comprising the step of computing the end-diastolic or pre-systolic cardiac volume V T and end-systolic or residual volume V R from the equation: ##EQU16## where D is the cardiac output determined by a classical method, Δ m and Δ m-1 being the tracer step concentration values at the m th and (m-1) th cardiac cycles.

Claim 4

The process according to claim 1, further comprising the step of computing the end-diastolic or pre-systolic cardiac volume V T and the end-systolic or residual volume V R from the equations: ##EQU17##

Claim 5

A process according to claim 1, further comprising the step of computing the end-diastolic or pre-systolic cardiac volume V T and the end-systolic or residual volume V R , using any pair of cardiac cycles n and n-1 occurring between the first cardiac cycle of the onset of the dilution curve (1) and the M th cardiac cycle at which the maximum step concentration Δ M occurs, from the equations: ##EQU18## where Δ n is the step concentration value at the n th cardiac cycle, where φ n is the fraction of the n th cardiac cycle during which injection takes place (0<φ n <1), where Δ n and Δ n-1 are chosen such that ##EQU19## Δ n-1 ≧0 and Δ n >0, τ being the mean cardiac cycle and where v is the injectate-volume-per-heartbeat quantity defined by the relationship: v=D i ·τ n .

Claim 6

A process according to claim 1, further comprising the step of computing the end-diastolic and pre-systolic volume V T and the end-systolic or residul volume V R from the m th cardiac cycle included between the M th cardiac cycle needed to reach the maximum step concentration Δ M and the N th cardiac cycle at which the value reached by the step concentration Δ m is sufficiently small, from the equations: ##EQU20## where Δ m is the step concentration value at the m th cardiac cycle and where τ is the mean cardiac cycle.

Claim 7

Apparatus for measuring cardiac volume of the beating heart, in pulsed flow conditions by dilution of a quantity Q i of tracer injected upstream of a ventricle, at controlled injection flow D i and during a controlled time t i by recording the stepwise tracer concentration Δ n during a number N of complete cardiac periods n downstream of the injection site, and by determining the cycle M at which maximum step concentration value Δ M occurs, as well as the mean cardiac cycle period obtained by the recording of the cardiac cycling intervals, i.e. the cardiac period τ n , whereby forming the following summation products: ##EQU21## where m is any cycle corresponding to or occuring after the M th cardiac cycle but before the N th cycle (M≦m<N), where M is the cycle at which the maximum step concentration value Δ M 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 τ(1;N) is the mean cardiac period over N cardiac cycles ##EQU22## where τ(m;N) is the mean cardiac period over the (N-(m-1)) cardiac cycles ##EQU23## whence the cardiac volumes are determined from the measured values (Δ n , τ n ) and from the aforementioned relationships (S,S'), said apparatus comprising: an injector for controlling the injectate flow rate; a transducer for measuring the variation in concentration downstream of the injection site; means for sampling values of the tracer curve Δ at a fixed rate and for recording the sample values; means for determining and for recording the step concentration value Δ n of each cardiac cycle n; means of recording the duration τ n of each cardiac cycle; means for determining the cardiac cycle M at which the step tracer concentration is maximum Δ M ; means for summing the tracer concentration Δ n in the first case between the first and the last (N) cardiac cycles of the tracer curve and, in the second case, between a cardiac cycle corresponding to or occurring after the cardiac cycle M, at which the maximum step concentration Δ M occurs, and the last cardiac cycle N of the dilution curve which is reached when the step concentration Δ n drops below a preset fraction of the maximum step concentration Δ M ; means for determining the average value of the period τ n of the cardiac cycle between the aforementioned same two time intervals; and means for computing the cardiac volumes from the aforementioned determined and stored values.

Claim 8

Apparatus for measuring cardiac volume of the beating heart, in pulsed flow conditions by dilution of a quantity Q i of tracer injected upstream of a ventricle, at controlled injection flow D i and during a controlled time t i by recording the stepwise tracer concentration Δ n during a number N of complete cardiac periods n downstream of the injection site, and by determining the cycle M at which maximum step concentration value Δ M occurs, as well as the mean cardiac cycle period obtained by the recording of the cardiac cycling intervals, i.e. the cardiac period τ n , whereby forming the following summation products: ##EQU21## where m is any cycle corresponding to or occuring after the M th cardiac cycle but before the N th cycle (M≦m<N), where M is the cycle at which the maximum step concentration value Δ M 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 τ(1;N) is the mean cardiac period over N cardiac cycles ##EQU22## where τ(m;N) is the mean cardiac period over the (N-(m-1)) cardiac cycles ##EQU23## whence the cardiac volumes are determined from the measured values (Δ n , τ n ) and from the aforementioned relationships (S,S'), said apparatus comprising: an injector for controlling the injectate flow rate; a transducer for measuring the variation in concentration downstream of the injection site; means for sampling values of the tracer curve Δ at a fixed rate and for recording the sample values; means for determining and for recording the step concentration value Δ n of each cardiac cycle n; means of recording the duration τ n of each cardiac cycle; means for determining the cardiac cycle M at which the step tracer concentration is maximum Δ M ; means for summing the tracer concentration Δ n in the first case between the first and the last (N) cardiac cycles of the tracer curve and, in the second case, between a cardiac cycle corresponding to or occurring after the cardiac cycle M, at which the maximum step concentration Δ M occurs, and the last cardiac cycle N of the dilution curve which is reached when the step concentration Δ n drops below a preset fraction of the maximum step concentration Δ M ; means for determining the average value of the period τ n of the cardiac cycle between the aforementioned same two time intervals; and means for computing the cardiac volumes from the aforementioned determined and stored values.

Claim 9

Apparatus according to claim 6, further including: a converter associated with said transducer for converting the output of the transducer into an electrical signal; an amplifier; means for applying said electrical signal to the input of said amplifier; a sequence generator for controlling the injector; an analog-digital converter; a data analyzer including a step detector; a step analyzer; a curve analyzer; a calcuator; and means for controlling said analog-digital converter, said data analyzer, said step analyzer, said curve analyzer, and said calculator from said sequence generator.