Left ventricular early diastolic filling and atrial contribution assessed by ECG-gated cardiac blood pool scintigraphy

This study evaluated early diastolic left ventricular (LV) filling and the atrial contribution to ventricular filling in patients (pts) with various heart diseases using ECG-gated cardiac blood pool scintigraphy. Conventional equilibrium list mode ECG-gated cardiac blood pool scintigraphy was performed for 19 normal subjects (N) as controls, 104 pts with old myocardial infarction (OMI), 19 pts with essential hypertension (HT), seven pts with idiopathic hypertrophic subaortic stenosis (IHSS), three pts with non-obstructive hypertrophic cardiomyopathy (HCM), 19 pts with pure mitral stenosis (MS) and one pt with both MS and aortic regurgitation to evaluate early diastolic LV filling. The LV stroke counts corresponding to stroke volume and the early diastolic LV peak filling rate (DdV/dt) were obtained from the LV time-activity curve and its first derivative. Then the DdV/dt was normalized by stroke counts. However, it has been difficult to assess the atrial contribution to ventricular filling by conventional ECG-gated cardiac blood pool scintigraphy. Therefore, to produce a more reliable late diastolic LV volume curve, a ''two-beat LV volume curve'' was constructed using a new method; namely, each cardiac cycle was divided into 20 msec segments in two different ways, i.e., backward and forward of the R wave, and the backward LV volume curve and forward LV volume curve (conventional method) were connected at the R wave. Then, to estimate the atrial contribution, an increment of counts after the beginning of the P wave divided by counts corresponding to the stroke volume (A(P)/SV) was calculated. DdV/dt obtained by conventional ECG-gated cardiac blood pool scintigraphy and A(P)/SV obtained by a ''two-beat LV volume curve'' are useful noninvasive parameters for assessing early diastolic LV filling and the atrial contribution to ventricular filling, respectively. (J.P.N.)