SYSTOLIC TIME INTERVALS (STI) AS INDICATORS OF MYOCARDIAL THYROID HORMONE EFFECT

1978 ◽  
Vol 87 (3) ◽  
pp. 507-515 ◽  
Author(s):  
J. Chakravarty ◽  
A. R. Guansing ◽  
S. Chakravarty ◽  
C. V. Hughes
Keyword(s):  
Thyroid Hormone ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Left Ventricular Ejection Time ◽  
Hormone Effect ◽  
Systolic Time ◽  
Ventricular Ejection Time

ABSTRACT Systolic time intervals consisting of indices of electromechanical systole (QS2-I), left ventricular ejection time (LVET-I) and pre-ejection period (PEP-I) were calculated serially during therapy in 12 euthyroid, 9 hypothyroid and 9 hyperthyroid individuals. These parameters were analyzed sequentially together with the changes in serum thyroxine (T4), triiodothyronine (T3) and thyrotrophin (TSH) in order to determine the sensitivity of these non-invasive procedures in monitoring peripheral thyroid hormone effect. The results are expreseed in mean ± sem. QS2-I (506.3 ± 8.2 ms) and PEP-I (102.9 ± 4.2) were shortened (P < 0.02 and P < 0.001, respectively) in hyperthyroidism and prolonged (579.3 ± 7.3 and 169.6 ± 3.6 ms) in hypothyroidism (P < 0.01 and P < 0.001, respectively) compared to euthyroid controls (538.1 ± 8.8 and 130.3 ± 5.3 ms), while LVET-I did not change significantly in either condition. Simultaneous determinations of circulating T4, T3 and TSH showed changes appropriate to both hypo- and hyperthyroid states. In 2 patients with T3-thyrotoxicosis, PEP-I was decreased to an average of 103.1 ms, while in 2 patients with compensated hypothyroidism (normal T4 but elevated TSH) this was prolonged to 163.7 ms (average) compared to euthyroid controls. During treatment the hypothyroid group showed significant sequential correlation of TSH and PEP-I. In the hyperthyroid individuals, PEP-I correlated significantly with T4 and T3. PEP-I may be a useful, sensitive, quantitative biologic indicator of thyroid hormone effect on myocardial function.

Reliability of noninvlasive methods for measuring cardiac function in exercise

1978 ◽  
Vol 44 (1) ◽  
pp. 55-58 ◽  
Author(s):  
L. A. Wolfe ◽  
D. A. Cunningham ◽  
G. M. Davis ◽  
P. A. Rechnitzer
Keyword(s):  
Cardiac Output ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Left Ventricular Ejection Time ◽  
Ejection Rate ◽  
Systolic Time ◽  
Ventricular Ejection Time

Externally recorded systolic time intervals (STI's), indirect (CO2 re-breathing) cardiac output, and auscultatory blood pressures were measured during upright bicycle ergometer work in 20 healthy men, aged 24–56 yr. The subjects were studied on 2 separate days at steady-state work loads chosen to represent light (mean heart rate (HR) = 96 beats.min-1), moderate (HR = 118 beats.min-1) and heavy (HR = 147 beats.min-1) exercise. In addition to determinations of cardiac output, systolic time intervals, and blood pressure, the individual's mean systolic ejection rate (stroke volume/left ventricular ejection time) was calculated as a measure of left ventricular function. In general, heart-rate-corrected STI's were found to be reliable and reproducible. Reliability coefficients for total electromechanical systole and left ventricular ejection time ranged from 0.93 to 0.96 while those for the preejection period and its subcomponents were between 0.63 and 0.88. The reliability of cardiac output, stroke volume, mean systolic ejection rate, and systolic blood pressure was also considered to be acceptable but tended to be higher during moderate and heavy work (r = 0.85–0.95) compared to light exercise (r = 0.60–0.83).

Systolic Time Intervals before and after Maximal Exercise in Adolescents with Insulin-Dependent Diabetes Mellitus

1992 ◽  
Vol 4 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Barbara N. Campaigne ◽  
Kyle W. Landt ◽  
Frederick W. James ◽  
Joan Reimar ◽  
Wayne Mays ◽  
...  
Keyword(s):  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Dependent Diabetes Mellitus ◽  
Ejection Time ◽  
Time Intervals ◽  
Left Ventricular Ejection Time ◽  
Before And After ◽  
Systolic Time ◽  
Ventricular Ejection Time

Systolic time intervals (STI) were measured before and after exercise in 18 diabetic adolescents (D) and 18 age- and sex-matched nondiabetic controls (C). At similar heart rates, pre-exercise pre-ejection period (PEP) and left ventricular ejection time (LVET) were significantly shorter in D compared to C (p<0.05). There was no difference between the two groups in the PEP/LVET ratio. Following exercise there were no differences in STIs between groups. However, the change in PEP and LVET from pre- to postexercise was significantly less in D compared to C (delta PEP 38 vs. 53±3 msec, p<0.01; delta LVET 120 vs. 134±4 msec, p<0.05). These data suggest a hypercontractile state at rest in D and a blunted response to exercise when compared to C. This study provides data that may be relevant to the early identification of individuals at risk for premature diabetic cardiomyopathy.

Neonatal Circulatory Changes: An Echocardiographic Study

PEDIATRICS ◽  
1977 ◽  
Vol 59 (3) ◽  
pp. 338-344
Author(s):  
Thomas Riggs ◽  
Stephen Hirschfeld ◽  
Connie Bormuth ◽  
Avroy Fanaroff ◽  
Jerome Liebman
Keyword(s):  
Right Ventricular ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Systolic Time ◽  
The Right ◽  
Ventricular Ejection Time

Serial echocardiograms were performed in the first three days of life on 38 normal full-term infants. Right ventricular systolic time intervals were measured from the pulmonic valve echogram and left ventricular systolic time intervals were determined from the aortic valve echogram. The heart rate, left ventricular pre-ejection period (LPEP), left ventricular ejection time (LVET), and LPEP/LVET ratio showed insignificant variation with increasing postnatal age. The right ventricular pre-ejection period (RPEP) shortened, the right ventricular ejection time (RVET) lengthened, and the RPEP/RVET ratio decreased with increasing age. The findings suggested that alterations in the RPEP/RVET ratio reflected the decreasing pulmonary artery diastolic pressure and pulmonary vascular resistance of the early neonatal period and may be valuable in the noninvasive evaluation of the newborn's pulmonary vascular bed.

Systolic time intervals during +Gz acceleration

1976 ◽  
Vol 41 (1) ◽  
pp. 52-56 ◽  
Author(s):  
T. B. Graboys ◽  
E. D. Michaelson
Keyword(s):  
Recovery Period ◽  
Systolic Time Intervals ◽  
Cardiovascular Function ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Physiological Variables ◽  
Systolic Time ◽  
Ventricular Ejection Time

Systolic time intervals (STI) were recorded in 8 healthy male volunteersbefore, during, and after 30-s exposures to +3 Gz, +5 Gz, and +7 Gz acceleration. Heart rate (HR) increased at all +Gz levels, as did the HR correctedQSIc interval, left ventricular ejection time (LVETc), preejection period (PEPc) and PEP/LVET. These changes in STI were also proportional to the +Gz level. At the higher +Gz levels, PEPc and PEP/LVET continued to increase early in the recovery period, but HR and all STI returned to control after 60s of recovery. Although physiological variables other than myocardial contractility, such as preload and afterload may influence STI during +Gz the effects of +Gz on stroke volume (SV) and cardiac output (CO) were estimated using previously described relationships between STI and invasively determined indices of cardiovascular function. In general CO increased as SV decreased. During recovery, HR and CO fell and CO remained slightly below controllevels, primarily because estimated SV remained low. This study demonstrates the feasibility of using STI to estimate noninvasively the transient changes in cardiovascular function during +Gz acceleration.

Value of Systolic Time Intervals in the Diagnosis of Large Patent Ductus Arteriosus in Fluid-Restricted and Mechanically Ventilated Preterm Infants

PEDIATRICS ◽  
1984 ◽  
Vol 74 (6) ◽  
pp. 1069-1074
Author(s):  
François Heitz ◽  
Jean-Claude Fouron ◽  
Nicolaas H. van Doesburg ◽  
Harry Bard ◽  
François Teasdale ◽  
...  
Keyword(s):  
Patent Ductus Arteriosus ◽  
Right Ventricular ◽  
Ductus Arteriosus ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Ejection Time ◽  
Time Intervals ◽  
Systolic Time ◽  
Ventricular Ejection Time ◽  
Patent Ductus

M-mode echocardiographic features suggesting a patent ductus arteriosus are based on two groups of indirect criteria: dilation of the left cardiac cavities and changes of systolic time intervals. The reliability of the first group of criteria has been questioned in fluidlimited, mechanically ventilated preterm infants. The sensitivity of the systolic time intervals in the same circumstances is investigated. Twenty-three patients with a large patent ductus arteriosus were selected. Review of their echocardiograms shows that the sensitivity of the various criteria (expressed as percentage of positivity) was as follows: inversion of the ratio of left ventricular preejection period to right ventricular preejection period, 91.3%; left ventricular preejection period to left ventricular ejection time over right ventricular preejection period to right ventricular ejection time &lt; 1, 83%; left atrium dilation, 74%; shortening of left ventricular preejection period, 70%; dilation of left ventricular internal dimensions in diastole, 65%; increase in left atrium/aorta, 52%; and decrease of left ventricular preejection period to left ventricular ejection time, 48%. Three criteria involving time intervals (left ventricular preejection period to right ventricular preejection period, left ventricular preejection period, and left ventricular preejection period to left ventricular ejection time) had 100% specificity. The lowest specificity was found with criteria involving the left atrium (left atrial to aortic root ratio 75% and left atrium 63%). It is concluded that study of systolic time intervals is a reliable means of detecting preterm infants with hemodynamically significant left-to-right shunt through a patent ductus arteriosus even if the infants are mechanically ventilated and fluid restricted.

Dynamics of cardiac output and systolic time intervals in supine and upright exercise

1983 ◽  
Vol 55 (6) ◽  
pp. 1674-1681 ◽  
Author(s):  
Y. Miyamoto ◽  
J. Higuchi ◽  
Y. Abe ◽  
T. Hiura ◽  
Y. Nakazono ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Response Times ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Upright Posture ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Supine Posture ◽  
Ventricular Ejection Time

Transient and steady-state responses of stroke volume (SV), heart rate (HR), cardiac output (Q), left ventricular ejection time (LVET), preejection period (PEP), and the ratio of LVET to PEP during bicycle exercises of 50 and 100 W were studied in four healthy male subjects in supine and upright postures. A computer-based system in which impedance cardiography was incorporated served to determine the above parameters on a 10-s interval basis. SV remained almost unchanged in response to exercises in a supine posture, whereas it increased significantly in an upright posture, although the individual differences among subjects were found to be large. The half-response times of variables to a step work load were determined. An approximate accordance was observed among the response times for HR, Q, and LVET/PEP. There was an inverse relationship between LVET and HR, the slope of which was found to be steeper in the supine posture than in the upright posture, reflecting the difference between the SV responses in both postures. LVET fell shortly after the cessation of exercise despite the decreasing HR. Inasmuch as the paradoxical reduction of LVET was also found in the case where SV remained unchanged in response to exercise, no changes in SV can be the cause thereof. Thus, a transient increase in ejection rate, which is due to either the increased myocardial contractility or decreased peripheral vascular resistance, may be responsible for the phenomenon.

Echographic Ventricular Systolic Time Intervals in Normal Term and Preterm Neonates

PEDIATRICS ◽  
1978 ◽  
Vol 62 (3) ◽  
pp. 317-321
Author(s):  
Henry Halliday ◽  
Stephen Hirschfeld ◽  
Thomas Riggs ◽  
Jerome Liebman ◽  
Avroy Fanaroff
Keyword(s):  
Right Ventricular ◽  
Preterm Infants ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Ejection Time ◽  
Time Intervals ◽  
Normal Term ◽  
Systolic Time ◽  
Ventricular Ejection Time

Right ventricular and left ventricular systolic time intervals (RVSTIs and LVSTIs) were measured in normal term and preterm infants from 1 hour to 90 days of life. LVSTIs in both term and preterm infants were similar in the first five days of life. The ratio of left pre-ejection period (LPEP) to left ventricular ejection time (LVET) was lower in preterm infants older than age 5 days. Estimated gestational age had no influence on LVSTI. The ratio of right preejection period (RPEP) to right ventricular ejection time (RVET) was lower in preterm infants (0.32) than in term newborns (0.37). The preterm RPEP/RVET ratio decreased with age, but at a slower rate than in term babies. This was consistent with the lower pulmonary vascular resistance present in preterm infants.

Higher exercise intensity delays postexercise recovery of impedance-derived cardiac sympathetic activity

2017 ◽  
Vol 42 (8) ◽  
pp. 834-840 ◽  
Author(s):  
Scott Michael ◽  
Ollie Jay ◽  
Kenneth S. Graham ◽  
Glen M. Davis
Keyword(s):  
Heart Rate ◽  
Neural Activity ◽  
Exercise Intensity ◽  
Systolic Time Intervals ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Natural Logarithm ◽  
Ventricular Ejection Time

Systolic time intervals (STIs) provide noninvasive insights into cardiac sympathetic neural activity (cSNA). As the effect of exercise intensity on postexercise STI recovery is unclear, this study investigated the STI recovery profile after different exercise intensities. Eleven healthy males cycled for 8 min at 3 separate intensities: LOW (40%–45%), MOD (75%–80%), and HIGH (90%–95%) of heart-rate (HR) reserve. Bio-impedance cardiography was used to assess STIs – primarily pre-ejection period (PEP; inversely correlated with cSNA), as well as left ventricular ejection time (LVET) and PEP:LVET – during 10 min seated recovery immediately postexercise. Heart-rate variability (HRV), i.e., natural-logarithm of root mean square of successive differences (Ln-RMSSD), was calculated as an index of cardiac parasympathetic neural activity (cPNA). Higher preceding exercise intensity elicited a slower recovery of HR and Ln-RMSSD (p < 0.001), and these measures did not return to baseline by 10 min following any intensity (p ≤ 0.009). Recovery of STIs was also slower following higher intensity exercise (p ≤ 0.002). By 30 s postexercise, higher preceding intensity resulted in a lower PEP (98 ± 14 ms, 75 ± 6 ms, 66 ± 5 ms for LOW, MOD, and HIGH, respectively, p < 0.001). PEP recovered to baseline (143 ± 11 ms) by 5 min following LOW (139 ± 13 ms, p = 0.590) and by 10 min following MOD (145 ± 17 ms, p = 0.602), but was still suppressed at 10 min following HIGH (123 ± 21 ms, p = 0.012). Higher preceding exercise intensity attenuated the recovery of indices for cSNA (from STIs) and cPNA (from HRV) in a graded dose–response fashion. While exercise intensity must be considered, acute recovery may be a valuable period during which to concurrently monitor these noninvasive indices, to identify potentially abnormal cardiac autonomic responses.

scholarly journals Improvement of Left Ventricular Ejection Time Measurement in the Impedance Cardiography Combined with the Reflection Photoplethysmography

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3036 ◽  
Author(s):  
Shing-Hong Liu ◽  
Jia-Jung Wang ◽  
Chun-Hung Su ◽  
Da-Chuan Cheng
Keyword(s):  
Impedance Cardiography ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Artificial Noise ◽  
Ejection Time ◽  
Left Ventricular Ejection Time ◽  
Noise Interference ◽  
Non Invasive ◽  
Ventricular Ejection Time

Cardiac stroke volume (SV) is an essential hemodynamic indicator that can be used to assess whether the pump function of the heart is normal. Non-invasive SV measurement is currently performed using the impedance cardiography (ICG). In this technology, left ventricular ejection time (LVET) is an important parameter which can be determined from the ICG signals. However, the ICG signals are inherently susceptible to artificial noise interference, which leads to an inaccurate LVET measurement and then yields an error in the calculation of SV. Therefore, the goal of the study was to measure LVETs using both the transmission and reflection photoplethysmography (PPG), and to assess whether the measured LVET was more accurate by the PPG signal than the ICG signal. The LVET measured by the phonocardiography (PCG) was used as the standard for comparing with those by the ICG and PPG. The study recruited ten subjects whose LVETs were simultaneously measured by the ICG using four electrodes, the reflection PPG using neck sensors (PPGneck) and the transmission PPG using finger sensors (PPGfinger). In each subject, ten LVETs were obtained from ten heartbeats selected properly from one-minute recording. The differences of the measured LVETs between the PCG and one of the ICG, PPGneck and PPGfinger were −68.2 ± 148.6 ms, 4.8 ± 86.5 ms and −7.0 ± 107.5 ms, respectively. As compared with the PCG, both the ICG and PPGfinger underestimated but the PPGneck overestimated the LVETs. Furthermore, the measured LVET by the PPGneck was the closest to that by the PCG. Therefore, the PPGneck may be employed to improve the LVET measurement in applying the ICG for continuous monitoring of SV in clinical settings.

Responses of peak ear-pulse derivative to changing left ventricular function

1980 ◽  
Vol 238 (3) ◽  
pp. H355-H359 ◽  
Author(s):  
Y. Nakamura ◽  
B. G. Haffty ◽  
D. H. Spodick ◽  
D. Paladino ◽  
K. Moreau ◽  
...  
Keyword(s):  
Ventricular Function ◽  
Cycle Length ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ejection Time ◽  
Pressure Derivative ◽  
Left Ventricular Ejection Time ◽  
Ejection Rate ◽  
Ventricular Ejection Time ◽  
Technical Reliability

The ear densitograph displacement pulse derivative (dD/dtear) is the analog of the arterial pressure derivative (dP/dt) and behaves comparably under a variety of cardiocirculatory challenges. Technical reliability and uniform application of the transducer are advantages that make it ideal for intrasubject monitoring. With atrial fibrillation as a model of functional variability in eight subjects, peak dD/dtear (P) tracked echocardiographic stroke volume, ejection fraction, ejection rate, and velocity of circumferential fiber shortening quite closely with the exception of some values in three subjects, two of whom had mitral regurgitation and one paradoxic septal movement. In all subjects, P showed good to excellent correlations with cycle length, preejection period (PEP), LVET (left ventricular ejection time), and PEP/LVET. The method appears to be ideally suited to intrasubject monitoring for changing ventricular function.

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