1. A miniature solid-state mercuric iodide (HgI2) nuclear probe detector has been developed in conjunction with a computerized nuclear probe (Nuclear Stethoscope) to enable continuous noninvasive monitoring of left ventricular function using 99Tc-labelled equilibrium blood pool techniques.
2. Left ventricular ejection fraction was measured in 54 patients undergoing radionuclide angiography with a gamma-camera and with the Nuclear Stethoscope and a good correlation was obtained between both techniques (r = 0.94, n = 54, P < 0.001).
3. The prototype mercuric iodide detector was compared with the sodium iodide detector of the Nuclear Stethoscope and a study in 41 consecutive patients demonstrated a good correlation for the measurement of ejection fraction, ejection rate, peak filling rate and time to peak filling rate (r = 0.94, 0.89, 0.90 and 0.78 respectively).
4. It may be possible to adapt the mercuric iodide detector for continuous non-invasive monitoring of left ventricular performance in critically ill patients and during physiological or pharmacological interventions.