Direct Correlation of External Systolic Time Intervals with Internal Indices of Left Ventricular Function in Man

Abstract

Direct correlation of externally measured systolic time intervals with internally measured indices was obtained using catheter-tip micromanometers in six patients who had normal coronary arteriograms. Simultaneous recordings were made of central aorta and left ventricular pressure, maximum rate of rise in left ventricular pressure (dp/dt), external carotid pulse, external and internal sound, and electrocardiogram. Acute interventions were used to vary the indices by a variety of mechanisms including changes in contractility, preload, afterload, and heart rate. The initial values and the changes in these values produced by acute interventions are identical for left ventricular ejection time (LVET) whether measured externally (range 175 to 385 msec) or internally (range 169 to 392), r = 0.99. Although the absolute values differed for internally measured isovolumic contraction time (internal ICT), externally measured ICT, and preejection time (PEP), there was good linear correlation between the changes observed in these values following the interventions. Changes in PEP and internal ICT showed excellent linear correlation (r = 0.94) and were also alike in absolute value following the interventions. The interval from the Q wave of the electrocardiogram to rise in left ventricular pressure (electrical-mechanical delay) did not change significantly during these interventions. During a period of spontaneous isorhythmic dissociation there was close tracking between beat-to-beat changes in PEP and internal ICT and between externally and internally measured LVET. Following acute interventions PEP and left ventricular dp/dt changed inversely. Externally measured systolic time intervals have therefore been shown in man to correlate well with directly measured internal indices, both in steady-state conditions and during a series of acute interventions. This convenient and atraumatic method has been shown to be a valid and sensitive measure of myocardial performance.

On the Reliability of Systolic Time Intervals

“…The same conclusions were reached by Martin et al [15]: the STI have been shown in man to correlate well with directly mea sured internal indices both under steady state conditions and during a series of interven tions including changes in contractivity, pre load. afterload and heart rate.…”

Clinical and phonocardiographic evaluation of left ventricular function in patients with chronic obstructive pulmonary disease

“…5,6,8 The internally measured systolic time intervals (PEP and LVET) correlate closely with the externally recorded PEP and LVET. 23,24 In addition, a highly significant correlation between the PEP/LVET and LV ejection fraction as measured by angiography has been demonstrated in a variety of cardiac diseases. 5 PEP prolongation, LVET shortening and an increase in PEP/LVET ratio is a characteristic pattern observed in patients with LV dysfunction, provided the patients are in sinus rhythm and do not have conduction defects or valvular heart diseases.…”

Enflurane-Induced Hypotension Modifies Transmural Blood Flow Distribution in the Canine Left Ventricle

“…As these parameters measured internally and externally were reported to correlate quite well with each other under various conditions (Martin et al 1971), the authors have tried to find out correlations mentioned above. As shown in Table 3, PEP and ICT were significantly prolonged from the control values by the inhalation of enflurane.…”