Electrical impedance cardiogram in derivation of systolic time intervals.

Balasubramanian, Vijay; Mathew, O P; Behl, Ajay S.; Tewari, Saipriya; Hoon, R S

doi:10.1136/hrt.40.3.268

Cited by 50 publications

(24 citation statements)

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“…The onset of left ventricular ejection has been identified as 15% of the dZ/dt signal [11,12], the point of rapid upstroke of dZ/dt [3,9,10] and the zero crossing of dZ/dt [2,[4][5][6][7][8]. When comparing these methods (zero crossing, rapid upstroke and 15 % dZ/dt) of determining STI with the AP method under normal conditions, clearly the best relationships are demonstrated with the zero crossing and rapid upstroke methods.…”

Section: Resultsmentioning

confidence: 99%

“…The utility of having the means to accurately deter mine STI noninvasively has been examined, by many authors, in regards to specific factors or cardiac anoma lies that can influence fluctuations in timing [1,2,3,[17][18][19], Accuracy in determining these intervals is, therefore, of utmost importance. We used only healthy dogs in this study.…”

Section: Resultsmentioning

confidence: 99%

“…Fur ther, coefficients of variation between signals within dog and indi vidual were assessed. In addition, from the same dZ/dt signals, STI were determined from the zero crossing method [2,6,7], the rapid upstroke method [3,5,9] and 15% dZ/dt method [11,12]. AP, delta Z and dZ/dt were determined simultaneously (see text).…”

Section: Measurement Of Stimentioning

confidence: 99%

“…Although systolic time intervals (STI) have classically been determined noninvasively by the combined utiliza tion of phonocardiography, a carotid pulse tracing, and electrocardiography to assess ventricular function [1], other noninvasive bioelectric impedance methods [2][3][4][5] have also been utilized to make these determinations. The first derivative of the impedance waveform (dZ/dt) has been used by several workers in the attempt to deter tromechanical systole (EMS)) were determined from the impedance signals and were compared to those simulta neously ascertained from the ascending AP waveforms.…”

Section: Introductionmentioning

confidence: 99%

“…mine the onset of left ventricular ejection. The zero crossing of dZ/dt (the point where the dZ/dt waveform crosses the baseline) has been described by some authors [2,[4][5][6][7][8]. Others have used the point of the rapid up stroke of dZ/dt [3,9,10].…”

mentioning

confidence: 99%

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Noninvasive Measurement of Systolic Time Intervals in the Dog Through the Use of Bioelectric Impedance

Demeter¹,

Hamburger²,

Toth³

et al. 1988

Am J Noninvas Cardiol

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Systolic time intervals which include pre-ejection period (PEP), electromechanical systole (EMS), and left ventricular ejection time (LVET) were recorded from the ascending aortic pressure (AP) waveform, and these values were compared to simultaneously derived measurements from the impedance waveform. In 11 male hounds anesthetized with 25 mg/kg thiopental, the changes in impedance (delta Z) and the first derivation (dZ/dt) of the latter waveform were studied over a heart rate range of 149-208 beats/min. The onset of the AP and delta Z waveforms along with the ejection point (E point) of the dZ/dt waveform (point on dZ/dt waveform that occurs at the same point in time as the most rapid upstroke point of delta Z), occurred simultaneously. The dicrotic notch (termination of LVET) of the AP and delta Z waveforms and the major downward deflection of dZ/dt also occurred simultaneously. Derived from the above mentioned waveforms, PEP ranged from 0.045 to 0.090 s (r = 1.0 in each case), LVET ranged from 0.120 to 0.190 s (r = 0.998), and EMS ranged from 0.180 to 0.250 s (r = 0.998). These results indicate that noninvasive bioelectric impedance techniques may allow for accurate determination of systolic time intervals.

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