Analysis of the Factors that may Influence the Duration of Isotonic Systole in Normal Conditions

Gobbato, F; Meda, A

doi:10.1159/000165596

Cited by 13 publications

(3 citation statements)

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“…The slopes of the regression equations relating heart rate and duration of ejection over the whole range of stroke volumes in each patient (Table IV) are approximately the same as that found by several inyestigators (17,23), but less than that observed by others (20,24,25). Differences in the slope of this relationship noted by these workers can be explained by the extent to which the interventions used to alter heart rate changed stroke volume as well.…”

Section: Discussionsupporting

confidence: 69%

Pressure-flow studies in man. An evaluation of the duration of the phases of systole

Harley¹,

Starmer²,

Greenfield³

1969

J. Clin. Invest.

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A B S TR A C T This study was designed to assess the independent effects of stroke volume and heart rate on the phases of systole and other selected hemodynamic parameters. By means of the pressure gradient technique instantaneous blood pressure and flow were recorded in the ascending aorta at fixed ventricular rates in five patients with complete heart block and in four patients with atrio-ventricular dissociation induced by ventricular pacing. Because of the variable contribution of atrial systole to ventricular filling, a wide range of stroke volumes were observed at each heart rate. The results indicate that the duration of ejection bears a close direct linear relationship to stroke volume while heart rate has only a weak but independent relation. On the other hand, the duration of total systole is related chiefly to the heart rate but stroke volume exerts an important independent effect. In a given patient, both duration of ejection and pulse pressure reflect changes of stroke volume and the product of the duration of ejection and the pulse pressure shows a good correlation with the stroke volume. INTRODUCTIONPrevious studies in man of the relationships between heart rate, stroke volume, and other hemodynamic parameters such as the phases of systole, have been limited by the methodological difficulties encountered in measuring phasic blood flow. The recent development of the pres-

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Section: Discussionsupporting

confidence: 69%

Pressure-flow studies in man. An evaluation of the duration of the phases of systole

Harley¹,

Starmer²,

Greenfield³

1969

J. Clin. Invest.

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“…This is in agreement with the findings of others [7,17,34,42,48], Changing the position from supine to sitting, the LVET decreases. This agrees with the findings of other investigators [27,34,36,56].…”

Section: V E T Intervalsupporting

confidence: 93%

Systolic Time Intervals at Rest and during Exercise

Cardús¹,

Vera²

1974

Cardiology

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Measurements of the electromechanical systole (QS₂) and its components: electromechanical delay (QS₁), isovolumic contraction time (ICT), and left ventricular ejection time (LVET), were conducted on 30 healthy men at rest and during exercise of varying intensity. The measurements were performed through simultaneous, non-invasive recordings of the electrocardiogram, phonocardiogram, and carotidogram. The conclusions are: (1) QS₂ and its components are principally correlated to the duration of the cardiac cycle (RR); (2) in changing posture from supine to sitting, the mean QS_t and mean ICT tend to increase, but these changes are not statistically significant. LVET and QS₂ are both significantly shortened; (3) during exercise there is a decrease in the mean values of QS_1’ ICT, LVET, and QS₂. The degree of LVET shortening is not as great as predicted by the ‘resting’ regression equation; (4) variations in arterial blood pressure and work load do not significantly affect systolic time intervals; (5) the effect of age on systolic time intervals is difficult to assess and needs further investigation.

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“…Constant heart rate may be achieved mathematically by calculating the corrected flow time (Ftc). Numerous Ftc formulae have been proposed and fall generally into linear [16][17][18][19][20][21][22][23] and non-linear [24][25][26] varieties. Furthermore, these formulae may be categorized by whether they correct for electrical systole (i.e., the duration from the onset of the Q wave to the end of the T wave) or mechanical systole (i.e., the duration from the upstroke of the pulse to the closure of the aortic valve).…”

Section: Introductionmentioning

confidence: 99%

Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

Kenny

MacKenzie

Eibl

et al. 2020

ICMx

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Background Change of the corrected flow time (Ftc) is a surrogate for tracking stroke volume (SV) in the intensive care unit. Multiple Ftc equations have been proposed; many have not had their diagnostic characteristics for detecting SV change reported. Further, little is known about the inherent Ftc variability induced by the respiratory cycle. Materials and methods Using a wearable Doppler ultrasound patch, we studied the clinical performance of 11 Ftc equations to detect a 10% change in SV measured by non-invasive pulse contour analysis; 26 healthy volunteers performed a standardized cardiac preload modifying maneuver. Results One hundred changes in cardiac preload and 3890 carotid beats were analyzed. Most of the 11 Ftc equations studied had similar diagnostic attributes. Wodeys’ and Chambers’ formulae had identical results; a 2% change in Ftc detected a 10% change in SV with a sensitivity and specificity of 96% and 93%, respectively. Similarly, a 3% change in Ftc calculated by Bazett’s formula displayed a sensitivity and specificity of 91% and 93%. FtcWodey had 100% concordance and an R2 of 0.75 with change in SV; these values were 99%, 0.76 and 98%, 0.71 for FtcChambers and FtcBazetts, respectively. As an exploratory analysis, we studied 3335 carotid beats for the dispersion of Ftc during quiet breathing using the equations of Wodey and Bazett. The coefficient of variation of Ftc during quiet breathing for these formulae were 0.06 and 0.07, respectively. Conclusions Most of the 11 different equations used to calculate carotid artery Ftc from a wearable Doppler ultrasound patch had similar thresholds and abilities to detect SV change in healthy volunteers. Variation in Ftc induced by the respiratory cycle is important; measuring a clinically significant change in Ftc with statistical confidence requires a large sample of beats.

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Analysis of the Factors that may Influence the Duration of Isotonic Systole in Normal Conditions

Cited by 13 publications

References 0 publications

Pressure-flow studies in man. An evaluation of the duration of the phases of systole

Pressure-flow studies in man. An evaluation of the duration of the phases of systole

Systolic Time Intervals at Rest and during Exercise

Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

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