Quantitation of the motion of the cardiac base in normal subjects by Doppler echocardiography.

Because the motion of the base of the heart plays a central role in its filling and emptying, we developed an original method to characterize the base motion dynamics throughout each cycle by use of pulsed Doppler echocardiography. A 100 Hz wall filter and low gain settings were used to record the low-frequency, high-energy Doppler signals generated by the motion of the base. From the apical four-chamber view, the sample volume was placed at the lateral margin and at the common septal margin of the tricuspid and mitral annuli. These signals were differentiated from left and right atrioventricular flows by their opposite direction, higher energy, timing, and unique audio signal. The dynamics of the cardiac base were quantitated in 17 normal subjects (31 +/- 13 years). The time relationship between transvalvular flows and the motion of the base was studied in nine normal subjects by matching recordings at the same RR interval. The Doppler signal of the motion of the cardiac base showed a succession of positive (apically directed) and negative (atrially directed) velocity waves. Differences in the dynamics of the cardiac base were demonstrated between its left and right components, probably related to different loading conditions and different myocardial mechanical properties. The relationship between the motion of the base and mitral flow as shown in this study suggests that Doppler-measured mitral flow velocity underestimates relative left ventricular inflow velocity with respect to the atrium by about 17% at peak early flow and by 20% at peak late flow. The method reported in the present study allows a more informative noninvasive quantitation of the cardiac base motion derived from measurements of its velocity, excursion, and acceleration. This new method may provide unique information on the left ventricular and right ventricular performance in the meridional direction.

Diagnostic and prognostic value of ambulatory electrocardiographic monitoring.

To evaluate the diagnostic and prognostic value of continuous ambulatory ECG (AECG) monitoring, we studied 124 patients with chest pain syndromes by stress myocardial perfusion scintigraphy (MPS) and AECG. MPS was classified as normal or with fixed or reversible defects involving one or more than one vascular territory. Positive AECGs were divided into those with mild (< or = 1.5 mm), moderate (1.5 to 2.5 mm), and severe (> or = 2.5 mm) ST segment displacement. Among 61 patients with a negative AECG, 93% had limited ischemia or normal scintigraphic studies. All 24 patients with moderately or severely positive AECGs had reversible defects on MPS. Among those with severely positive AECGs, nine (75%) had multivessel scintigraphic ischemia. Severe ST segment depression on AECG was highly related to multivessel perfusion defects and to a large amount of myocardium in jeopardy. A negative AECG generally indicated limited or absent ischemia and thus a more benign prognosis. Induced symptoms and the daily ischemic burden were not related to the severity of induced AECG or MPS abnormalities. AECG may provide independent information as to the severity and related risk of ischemia.