Influence Diastolic
of Age, Body Size and Heart Indexes in Young Subjects
Shannon M. Holmgren,
Stanley J. Goldberg,
Rate on Left Ventricular
MD, and Richard
ecently, a number of echocardiographic measurements have been proposed to assessdiastolic . function. l,* Isovolumic relaxation time is closely correlated with early cardiac relaxation. Isovolumic relaxation time increases as relaxation becomes abnormal and with aging. Deceleration time provides a measure of the end of relaxation and the beginning of the diastolic compliance phase. Shortening of deceleration time occurs with restriction to ventricular flling. We selected these 2 measurements for study because both are easily obtained from a Doppler mitral tracing. However, some echocardiographic indexes of systolic function are known to be influenced by heart rate, body size or age, or a combination of all 3.3-s Our purpose in this study was to determine if isovolumic relaxation time and deceleration time are age-, heart rate- or body size-dependent in a pediatric and young adult group.
R
The study group consisted of 31 normal, healthy subjects, ages 1 day to 21 years (mean f standard deviation [SD] 9 f 5 years), with no evidence or history of heart disease. For each subject, age, height, weight and blood pressure were recorded and body surface area was calculated. Echocardiographic studies were performed with a Hitachi CVC 151 echocardiographic system (Hitachi Medical Inc., Tokyo, Japan) operating at 2.5, 3.5 or 5 MHz. M-mode tracings, acquired from the parasternal short-axis plane, were used to measure systolic and diastolic left ventricular diameter and posterior wall thickness according to criteria of the American Society of Echocardiography.6 Pulsed-wave Doppler echocardiography was performed to obtain isovolumic relaxation and deceleration times from a sample volume located at the tips of the mitral leaflets. Deceleration time was determined as the interval from peak mitral velocity to extrapolated or actual baseline crossing. Isovolumic relaxation time was identified as the interval between closure of the aortic valve and opening of the mitral valve as shown at commencement of mitral velocity (Figure 1). Aortic leaflet motion could be recorded simultaneously with the mitral velocity.
L. Donnerstein,
MD
Measurements were obtained at a video sweep speed of 100 mm/s using electronic calipers, and time resolution was 5 ms (new data sampling rate). The mean of >_3beats was reported for both isovolumic relaxation and deceleration times. Heart rate was determined for each isovolumic relaxation and deceleration time using the prior RR value of a simultaneously recorded electrocardiographic tracing. Influence of age, height, weight, body surface area, bloodpressure, heart rate and M-mode measurements on deceleration and isovolumic relaxation times was assessed using linear regression analysis. Isovolumic relaxation time ranged from 34 to 71 ms (mean f SD 55 f 1O), and deceleration time ranged from 48 to 139 ms (mean f SD 100 f 22). Isovolumic relaxation time correlated significantly with age (r = 0.79, p = O.OOOl), height (r = 0.72, p = 0.0001 ), body surface area (r = 0.70, p = 0.0001), weight (r = 0.66, p = O.OOOl),left ventricular cavity dimension in diastole (r = 0.56, p = 0.0014) and systolic blood pressure (r = 0.54, p = 0.0033). Deceleration time correlated significantly with height (r = 0.67, p = O.OOOl), body surface area (r = 0.66, p = O.OOl), age (r = 0.64, p = O.OOOl), weight (r = 0.64, p = 0.0001) and left ventricular posterior wall thickness in systole and diastole (r = 0.63, p = 0.0002; r = 0.60, p = 0.0005). Because many of the variables were interdependent, stepwise linear regression analysis was then performed. Results revealed
‘DT
FIGURE 1. Measurement method (IVRT) (feff panel) and deceleration
’
for isovohmk retaxation times (DT) (right pane/)
From the University of Arizona College of Medicine and Steele Memoon a digitixed and labeled mitral velocfty recording. lsovohunii rial Children’s Research Center, Department of Pediatrics, Tucson, relaxation time is recorded by lengthening the sample vohane Arizona. This study was supported in part by National Institutes of to include the aortic (Ao) valve motion in the Doppler range Health Grant T35HL07479-06-10, Bethesda, Maryland. Dr. Goldgate when the gate is centered on the left ventricular inflow berg’s address is: Department of Pediatrics (Cardiology), University of tract. Daceleration time is measured as a time interval beginArizona Health Sciences Center, Tucson, Arizona 857’24. Manuscript ning with the E point and ending at the point where an extrapreceived May 13, 1991; revised manuscript received and accepted July olated or actual line of decelerating velocity crosses the zero 8.1991.
velocity
basellne.
BRIEF REPORTS
1245
160
I
160
_-+
140
A.---
--
__I- **--
C--
*---
40
D
...,.'.'.',"....'.,.'.',' 0.0 5.0
10.0
15.0
20""""."".'. 0.0
20.0
-
1.0
(years)
AGE
BSA
."I*
2.0
(M*)
FIGURE 2. Normal left ventricular diastolic function in young subjects with respect to age and body surface area (BSA). Isovolumic retaxation time (IVRT) correlates most strongly with (A) age (r = 0.79, p
of Age, Body Size and Heart Indexes in Young Subjects
Shannon M. Holmgren,
Stanley J. Goldberg,
Rate on Left Ventricular
MD, and Richard
ecently, a number of echocardiographic measurements have been proposed to assessdiastolic . function. l,* Isovolumic relaxation time is closely correlated with early cardiac relaxation. Isovolumic relaxation time increases as relaxation becomes abnormal and with aging. Deceleration time provides a measure of the end of relaxation and the beginning of the diastolic compliance phase. Shortening of deceleration time occurs with restriction to ventricular flling. We selected these 2 measurements for study because both are easily obtained from a Doppler mitral tracing. However, some echocardiographic indexes of systolic function are known to be influenced by heart rate, body size or age, or a combination of all 3.3-s Our purpose in this study was to determine if isovolumic relaxation time and deceleration time are age-, heart rate- or body size-dependent in a pediatric and young adult group.
R
The study group consisted of 31 normal, healthy subjects, ages 1 day to 21 years (mean f standard deviation [SD] 9 f 5 years), with no evidence or history of heart disease. For each subject, age, height, weight and blood pressure were recorded and body surface area was calculated. Echocardiographic studies were performed with a Hitachi CVC 151 echocardiographic system (Hitachi Medical Inc., Tokyo, Japan) operating at 2.5, 3.5 or 5 MHz. M-mode tracings, acquired from the parasternal short-axis plane, were used to measure systolic and diastolic left ventricular diameter and posterior wall thickness according to criteria of the American Society of Echocardiography.6 Pulsed-wave Doppler echocardiography was performed to obtain isovolumic relaxation and deceleration times from a sample volume located at the tips of the mitral leaflets. Deceleration time was determined as the interval from peak mitral velocity to extrapolated or actual baseline crossing. Isovolumic relaxation time was identified as the interval between closure of the aortic valve and opening of the mitral valve as shown at commencement of mitral velocity (Figure 1). Aortic leaflet motion could be recorded simultaneously with the mitral velocity.
L. Donnerstein,
MD
Measurements were obtained at a video sweep speed of 100 mm/s using electronic calipers, and time resolution was 5 ms (new data sampling rate). The mean of >_3beats was reported for both isovolumic relaxation and deceleration times. Heart rate was determined for each isovolumic relaxation and deceleration time using the prior RR value of a simultaneously recorded electrocardiographic tracing. Influence of age, height, weight, body surface area, bloodpressure, heart rate and M-mode measurements on deceleration and isovolumic relaxation times was assessed using linear regression analysis. Isovolumic relaxation time ranged from 34 to 71 ms (mean f SD 55 f 1O), and deceleration time ranged from 48 to 139 ms (mean f SD 100 f 22). Isovolumic relaxation time correlated significantly with age (r = 0.79, p = O.OOOl), height (r = 0.72, p = 0.0001 ), body surface area (r = 0.70, p = 0.0001), weight (r = 0.66, p = O.OOOl),left ventricular cavity dimension in diastole (r = 0.56, p = 0.0014) and systolic blood pressure (r = 0.54, p = 0.0033). Deceleration time correlated significantly with height (r = 0.67, p = O.OOOl), body surface area (r = 0.66, p = O.OOl), age (r = 0.64, p = O.OOOl), weight (r = 0.64, p = 0.0001) and left ventricular posterior wall thickness in systole and diastole (r = 0.63, p = 0.0002; r = 0.60, p = 0.0005). Because many of the variables were interdependent, stepwise linear regression analysis was then performed. Results revealed
‘DT
FIGURE 1. Measurement method (IVRT) (feff panel) and deceleration
’
for isovohmk retaxation times (DT) (right pane/)
From the University of Arizona College of Medicine and Steele Memoon a digitixed and labeled mitral velocfty recording. lsovohunii rial Children’s Research Center, Department of Pediatrics, Tucson, relaxation time is recorded by lengthening the sample vohane Arizona. This study was supported in part by National Institutes of to include the aortic (Ao) valve motion in the Doppler range Health Grant T35HL07479-06-10, Bethesda, Maryland. Dr. Goldgate when the gate is centered on the left ventricular inflow berg’s address is: Department of Pediatrics (Cardiology), University of tract. Daceleration time is measured as a time interval beginArizona Health Sciences Center, Tucson, Arizona 857’24. Manuscript ning with the E point and ending at the point where an extrapreceived May 13, 1991; revised manuscript received and accepted July olated or actual line of decelerating velocity crosses the zero 8.1991.
velocity
basellne.
BRIEF REPORTS
1245
160
I
160
_-+
140
A.---
--
__I- **--
C--
*---
40
D
...,.'.'.',"....'.,.'.',' 0.0 5.0
10.0
15.0
20""""."".'. 0.0
20.0
-
1.0
(years)
AGE
BSA
."I*
2.0
(M*)
FIGURE 2. Normal left ventricular diastolic function in young subjects with respect to age and body surface area (BSA). Isovolumic retaxation time (IVRT) correlates most strongly with (A) age (r = 0.79, p
