Die Methode der radiokardiographischen Funktionsanalyse

Beat-to-beat left ventricular performance assessed from the equilibrium cardiac blood pool using a computerized nuclear probe

The feasibility, accuracy and reproducibility of continuous beat-to-beat evaluation of left ventricular performance with a computerized nonimaging scintillation probe was assessed in 71 patients. This portable instrument has enough sensitivity to generate a real-time relative left ventricular volume curve using the labeled equilibrium blood pool without electrocardiographic gating. The probe was positioned at the left ventricular and background regions of interest using a systematic series of computerized algorithms and operator routines that were developed and standardized during the initial phase of this study. In each patient, left ventricular ejection fraction was calculated manually from the strip-chart recording in 10 consecutive sinus beats. Beat-to-beat left ventricular ejection fraction determined by the probe correlated well with first-pass studies obtained using a computerized multicrystal scintillation camera (r = 0.92). There was no systematic over- or underestimation, and the correlation was evident over a wide range of first-pass values (15-81%). There was excellent agreement between initial and repeat analyses (n = 58, r = 0.97) and between initial and repeat studies (n = 48, r = 0.94). The absolute variability of beat-to-beat ejection fraction measurements determined from all 710 beats was +/- 5.9% (expressed in ejection fraction units as +/- 2 SD). This technique should provide a reliable means of addressing pathophysiologic questions that require sampling of data directly on a beat-to-beat basis.

Radionuclide evaluation of left ventricular function with nonimaging probes

Portable nonimaging probes have been developed that can evaluate left ventricular function using radionuclide techniques. Two modes of data acquisition are possible with these probe systems, first-pass and gated. Precordial radiocardiograms obtained after a bolus injection can be used to determine cardiac output, pulmonary transit time, pulmonary blood volume, left ventricle ejection fraction, and left-to-right shunts. Gated techniques can be used to determine left ventricular ejection fraction and sytolic time intervals. Probe-determined indices of left ventricular function agree excellently with comparable measurements determined by conventional camera-computer methods as well as by invasive techniques. These have begun to be used in a preliminary manner in a variety of clinical problems associated with left ventricular dysfunction. This review discusses the types of probe systems available, the methods used in positioning them, and details the specifics of their data acquisition and processing capacity. The major criticisms of probe methods are that they are nonimaging and that they measure global rather than regional left ventricular function. In spite of these criticisms, probe systems, because of their portability, high sensitivity, and relatively low cost are useful supplements to conventional camera-computer systems for the measurement of parameters of left ventricular performance using radionuclide techniques.

[Quantitative gated nuclear cardiography for noninvasive evaluation of left ventricular function]

In 43 patients with angiographically proven coronary heart disease and in 24 patients without heart disease, gated blood pool scintigraphy was done under resting conditions with 15 mCi 99mTcHSA in LAO projection. Scintigraphic data were collected in list mode by means of a gamma camera connected to a computer system (Siemens 330). A cumulative scintigram sequence with a time resolution of 100 frames/s was constructed using several hundred heart cycles of equal duration. After background correction volume curves of the left ventricle were obtained and the following parameters were calculated: EF, dV/dt max,dV/dt min. In all patients with coronary heart disease, these parameters were reduced depending on the severity of the stenotic lesion. The changes of dV/dt min and to a greater extend of dV/dt max were more pronounced than those of the EF. These results are in keeping with invasively obtained data which show that a decrease of myocardial compliance is one of the earliest manifestations of CHD. Quantitative gated nuclear cardiography allows, therefore, noninvasive evaluation of left ventricular function even under resting conditions.