Background
Echocardiographic imaging assessment of left ventricular mechanics is a new technology that is offered by various vendors. Different software algorithms have at times yielded conflicting results. The aim of this study was to determine normal myocardial mechanical parameters in a healthy population using Velocity Vector Imaging.
Methods
One hundred twenty subjects were selected for this study, including healthy subjects referred for echocardiography to evaluate minor symptoms or murmurs, who had normal echocardiographic findings and healthy volunteers. Study subjects were recruited in Haifa, Israel and Toronto, Canada. Echocardiography was performed using commercially available systems to analyze archived studies. Endocardial and epicardial longitudinal and circumferential strain and strain rate were calculated as well as rotational mechanical parameters. Age and gender differences were evaluated.
Results
Average endocardial longitudinal, circumferential, and radial strains and twist were −19.6 ± 2.0%, −27.6 ± 3.9%, +30.1 ± 7.5%, and 9.6 ± 3.9°, respectively. Epicardial circumferential strain and twist were −11.3 ± 2.2% and 4.0 ± 1.9°, respectively. Shortening increased from base to apex longitudinally (10%) and circumferentially (33%). Thickening at the apex was 16% lower than at the base. Men and older subjects had increased endocardial circumferential strain and apical rotation.
Conclusions
Mechanical parameters differ with location (endocardial vs epicardial, basal vs apical strain gradients), age, and gender. Care should be taken when comparing regional strain measurements between systems, and gender and age should be matched between and within two-dimensional strain systems.
Echocardiographic assessment of left ventricular (LV) mechanics uses relatively new technology that is now offered by various vendors. Although methodology has been validated, processing algorithms differ among vendors, and results may not be comparable and at times have even yielded conflicting findings. Thus, system-specific standards measured in a normal population are required. Such a study was recently published for longitudinal strain using EchoPAC (GE Vingmed Ultrasound AS, Horten, Norway), but results have not been published for Velocity Vector Imaging (VVI; Siemens Medical Solutions USA, Inc., Mountain View, CA). An advantage of VVI software is its ability to analyze myocardial mechanics from any ultrasound system stored in Digital Imaging and Communications in Medicine format. This substantially enlarges the number of studies available for analysis in echocardiography laboratories with machines from multiple vendors, provided that no machine-specific differences are found. A new version of VVI that allows selective measurement of both subendocardial and subepicardial strain parameters was available to us. Our goals were to describe endocardial and epicardial longitudinal and circumferential mechanics analyzed by VVI in a normal population, exploring age and gender differences as well as acquisition and storage (machine source and frame rates) differences.
Methods
Study Population
Subjects selected for this study included consecutive patients referred for elective echocardiography to evaluate minor symptoms or benign murmurs during 2009. Conventional echocardiographic studies had to be reported as having normal results, and clinically, patients had to be healthy, without major illnesses, and free of cardiovascular risk factors. A second group of patients included healthy volunteers free of cardiovascular risk factors. Study subjects were recruited in Haifa, Israel, and Toronto, Canada.
Conventional Echocardiography
Echocardiography was performed using Sequoia (Siemens Medical Solutions USA, Inc.), iE33 (Philips Medical Systems, Best, The Netherlands), and Vivid 7 (GE Vingmed Ultrasound AS) systems. Studies were done and reported according to accepted guidelines of the American Society of Echocardiography and saved for further analysis in the laboratory Digital Imaging and Communications in Medicine archive.
LV Mechanics
Measurements were performed using VVI software version 2.5.1 from archived studies ( Figures 1 and 2 ). Using VVI’s clip editor, QRS frames were marked and two or three consecutive cycles were selected for analysis for each view. Endocardial and epicardial contours were then traced and processed. Averaged endocardial and epicardial circumferential strain, strain rate (SR), and rotation velocities and angles and radial strain and SR were measured at three parasternal short-axis planes (basal, mid, and apical) in six segments per short-axis section. Endocardial and epicardial longitudinal strain and SR were measured from the apical four-chamber, two-chamber, and three-chamber views in six segments per view.
Ventricular Twist
Averaged myocardial rotation angles were used to calculate LV twist, defined as the maximal instantaneous basal-to-apical angle difference. Rotation and twist timing was standardized to cycle length.
Diastolic Mechanics
Systolic and early diastolic peak SR were measured in the longitudinal and circumferential axes. We showed in a previous report that peak systolic and early diastolic SR were both lower longitudinally and higher circumferentially. Assuming that systolic and diastolic function are interrelated, we needed a new parameter to identify systolic-independent diastolic abnormalities. The ratio of peak early diastolic to peak systolic SR ratio (SR E/S ratio) was calculated ( Figure 2 A) to assess whether the diastolic and systolic extent of changes were disproportionate.
We used fractional early apical reverse rotation (FEARR) to assess early LV relaxation. We measured the fractional decrease in rotation angle from its peak value to its value 10% of the cycle length later, using the equation shown in Figure 2 B. The threshold of 10% diastolic time was selected because it was previously reported to demonstrate the largest decrease in fractional reverse rotation for moderate compared with mild LV hypertrophy.
Reproducibility
For intraobserver variability, 10 randomly assigned patients were reanalyzed by the same observer (S.C.) several months after the initial analysis. For interobserver variability, the same patients and the exact same loops were analyzed by a second observer (P.B.).
Statistical Analysis
Continuous data are reported as mean ± SD. Assuming a non-normal distribution, nonparametric tests were used. Gender subgroups as well as strain gradients (endocardial and epicardial) were compared using Wilcoxon’s rank-sum test. Differences among age subgroups, segments, short-axis strain gradients (basal, mid, and apical), and images from various echocardiographic machines were assessed using analysis of variance with Tukey’s post hoc test. P values < .05 were considered statistically significant. For test performance, intraobserver and interobserver variability, intraclass correlation coefficients with 95% confidence intervals (CIs) were calculated, because they take the bias between observations into account. Statistical analyses were performed using SPSS release 11.0 (SPSS, Inc., Chicago, IL).
Results
Patients
Patients were consecutively recruited during 2009. Of a potential 142 normal subjects who met the inclusion criteria, 120 patients had VVI-analyzable studies. Their age ranged from 19 to 84 years (median, 39 years), and 55% were men. The distribution of referral diagnoses is shown in Figure 3 A. Assignment to echocardiographic machines was random and reflected machine availability ( Figure 3 B), except for a group of Canadian volunteers who were imaged on the Vivid 7 system but analyzed using VVI software. Most of the subjects ( n = 88) were enrolled in Israel and the rest in Canada.
Two-Dimensional (2D) Doppler Echocardiography
All conventional echocardiographic parameters were within the accepted normal ranges for gender, age, and heart rate ( Table 1 ). Women demonstrated significantly lower LV mass of about 10%, while ejection fraction, Doppler, and tissue Doppler parameters were similar. Age was not associated with 2D echocardiographic changes. Expected age-related significant changes in the mitral inflow parameters and annular velocities were demonstrated.
| By gender | By age (y) | |||||
|---|---|---|---|---|---|---|
| Variable | All patients ( n = 120) | Men ( n = 66) | Women ( n = 54) | <40 ( n = 62) | 40–59 ( n = 37) | >60 ( n = 21) |
| Male gender | 66 (55%) | 36 (50%) | 21 (57%) | 9 (43%) | ||
| Age (y) | 41 ± 13 | 41 ± 14 | 45 ± 14 | 32 ± 6 | 48 ± 5 † | 66 ± 6 ‡ |
| Body surface area (m 2 ) | 1.85 ± 0.19 | 1.94 ± 0.16 | 1.71 ± 0.14 ∗ | 1.86 ± 0.19 | 1.87 ± 0.18 | 1.81 ± 0.20 |
| 2D echocardiography | ||||||
| LV diastolic diameter (cm) | 4.8 ± 0.4 | 4.9 ± 0.4 | 4.7 ± 0.3 ∗ | 4.9 ± 0.4 | 4.8 ± 0.3 | 4.6 ± 0.3 † |
| LV systolic diameter (cm) | 3.1 ± 0.4 | 3.1 ± 0.3 | 2.9 ± 0.3 ∗ | 3.0 ± 0.4 | 3.1 ± 0.2 | 2.8 ± 0.3 †,‡ |
| Septal thickness (cm) | 0.8 ± 0.1 | 0.9 ± 0.1 | 0.8 ± 0.1 ∗ | 0.8 ± 0.1 | 0.9 ± 0.1 | 1.0 ± 0.1 †,‡ |
| Posterior wall thickness (cm) | 0.8 ± 0.1 | 0.8 ± 0.1 | 0.7 ± 0.1 | 0.7 ± 0.1 | 0.8 ± 0.1 | 0.8 ± 0.1 |
| Ejection fraction (%) | 66 ± 9 | 65 ± 10 | 67 ± 6 | 66 ± 7 | 65 ± 11 | 67 ± 4 |
| LV mass (g) | 128 ± 25 | 138 ± 25 | 114 ± 20 ∗ | 128 ± 26 | 126 ± 24 | 136 ± 28 |
| LV mass index (g/m 2 ) | 69 ± 11 | 71 ± 12 | 65 ± 9 | 69 ± 12 | 67 ± 11 | 76 ± 12 † |
| LA size (cm) | 3.5 ± 0.3 | 3.5 ± 0.3 | 3.4 ± 0.3 | 3.4 ± 0.3 | 3.5 ± 0.3 | 3.7 ± 0.4 † |
| Mitral inflow | ||||||
| E/A ratio | 1.3 ± 0.4 | 1.4 ± 0.5 | 1.3 ± 0.4 | 1.5 ± 0.4 | 1.3 ± 0.3 | 1.0 ± 0.3 †,‡ |
| Mitral E velocity (cm/sec) | 77 ± 19 | 75 ± 18 | 80 ± 20 | 78 ± 22 | 79 ± 15 | 73 ± 17 |
| Mitral E deceleration time (msec) | 196 ± 47 | 202 ± 54 | 190 ± 35 | 186 ± 44 | 191 ± 30 | 231 ± 57 †,‡ |
| Tissue Doppler | ||||||
| E′ septal velocity (cm/sec) | 11 ± 3 | 10 ± 3 | 11 ± 3 | 14 ± 3 | 10 ± 2 † | 8 ± 1 †,‡ |
| E′ lateral velocity (cm/sec) | 13 ± 4 | 13 ± 4 | 13 ± 4 | 16 ± 5 | 12 ± 3 † | 10 ± 3 †,‡ |
| Mitral E/E′ ratio | 7.4 ± 2.9 | 7.5 ± 2.8 | 7.2 ± 3 | 4.5 ± 2 | 8.8 ± 2.2 † | 9.0 ± 2.3 † |
| Pulmonary pressure (mm Hg) | 25 ± 4 | 25 ± 4 | 25 ± 3 | 25 ± 4 | 25 ± 4 | 28 ± 4 † |
† P < .05 versus age < 40 years.
Two-Dimensional Strain Imaging
Acquired clips had 14 to 57 frames per heart cycle (median, 24 frames per heart cycle), corresponding to a heart rate ranging from 41 to 90 beats/min (median, 64 beats/min). Of 2,160 potential segments, 2,061 (95%), 2,021 (94%), 1,990 (92%), and 1,945 (90%) were analyzable for longitudinal, endocardial circumferential, epicardial circumferential, and radial strain assessment, respectively.
Longitudinal Mechanics
The average longitudinal strain was −20 ± 2.0% and demonstrated a small yet significant apical-to-basal gradient that was similar by gender and age ( Table 2 , Figure 4 A). Basal inferior septal and inferior wall strain were lowest (−16 ± 3%). Women had a slightly higher average longitudinal strain. Systolic and early diastolic SR followed the same pattern, with a significant decrease in the early diastolic to systolic SR ratio (SR E/S) with older age. There was also a significant increase in the late diastolic SR (SR A) with age. Epicardial longitudinal strain was significantly lower than endocardial strain only in apical segments (up to 50% lower; Figure 4 ), resulting in a nonsignificantly lower average epicardial strain (−20 ± 2% vs −18 ± 4% for endocardial and epicardial strain, respectively, P > .10).
| By gender | By age (y) | |||||
|---|---|---|---|---|---|---|
| Variable | All patients ( n = 120) | Men ( n = 66) | Women ( n = 54) | <40 ( n = 62) | 40–59 ( n = 37) | >60 ( n = 21) |
| Strain (%) | −19.6 ± 2 | −19.1 ± 1.9 | −20.0 ± 2.4 ∗ | −19.6 ± 2.1 | −19.5 ± 1.9 | −19.4 ± 2.7 |
| Base | −19.2 ± 2.3 | −18.7 ± 2.1 | −19.7 ± 2.5 ∗ | −19.2 ± 2.2 | −19.3 ± 2.6 | −18.8 ± 2.6 |
| Mid | −18.1 ± 2.5 | −17.7 ± 2.3 | −18.5 ± 2.6 | −18.5 ± 2.5 | −17.6 ± 2.0 | −17.5 ± 3.0 |
| Apex | −21.3 ± 3.2 § | −21.0 ± 2.6 ‡ | −21.8 ± 3.8 § | −21.1 ± 3.0 § | −21.5 ± 3.4 § | −21.7 ± 3.5 § |
| Systolic SR (sec −1 ) | −1.02 ± 0.12 | −1.02 ± 0.12 | −1.01 ± 0.13 | −1.02 ± 0.12 | −1.04 ± 0.11 | −1.01 ± 0.15 |
| Base | −1.00 ± 0.13 | −1.00 ± 0.13 | −1.03 ± 0.12 | −1.00 ± 0.12 | −1.03 ± 0.14 | −0.97 ± 0.15 |
| Mid | −0.93 ± 0.14 | −0.92 ± 0.12 | −0.94 ± 0.15 | −0.95 ± 0.13 | −0.92 ± 0.11 | −0.90 ± 0.17 |
| Apex | −1.14 ± 0.20 § | −1.13 ± 0.19 § | −1.14 ± 0.21 § | −1.11 ± 0.19 ‡ | −1.17 ± 0.21 § | −1.16 ± 0.19 § |
| Early diastolic SR (sec −1 ) | 1.04 ± 0.28 | 1.01 ± 0.32 | 1.09 ± 0.2 | 1.06 ± 0.32 | 1.09 ± 0.23 | 0.93 ± 0.17 ‡ |
| Base | 0.98 ± 0.28 | 0.94 ± 0.33 | 1.04 ± 0.19 | 1.00 ± 0.32 | 1.02 ± 0.24 | 0.87 ± 0.16 ‡ |
| Mid | 0.94 ± 0.27 | 0.90 ± 0.30 | 0.99 ± 0.22 | 0.98 ± 0.31 | 0.94 ± 0.20 | 0.80 ± 0.17 ‡ |
| Apex | 1.21 ± 0.36 § | 1.18 ± 0.38 § | 1.26 ± 0.33 § | 1.19 ± 0.39 ‡ | 1.30 ± 0.36 § | 1.13 ± 0.25 ‡,§ |
| SR E/S ratio | 1.04 ± 0.13 | 1.02 ± 0.13 | 1.05 ± 0.12 | 1.07 ± 0.1 | 1.04 ± 0.14 | 0.93 ± 0.11 § |
| Late diastolic SR (sec −1 ) | 0.37 ± 0.12 | 0.36 ± 0.12 | 0.39 ± 0.13 | 0.31 ± 0.09 | 0.42 ± 0.13 † | 0.46 ± 0.10 † |
| Base | 0.40 ± 0.14 | 0.40 ± 0.15 | 0.42 ± 0.14 | 0.34 ± 0.12 | 0.46 ± 0.16 † | 0.48 ± 0.11 † |
| Mid | 0.37 ± 0.13 | 0.35 ± 0.13 | 0.38 ± 0.13 | 0.31 ± 0.10 | 0.41 ± 0.15 † | 0.45 ± 0.11 † |
| Apex | 0.35 ± 0.14 § | 0.33 ± 0.12 § | 0.37 ± 0.16 § | 0.28 ± 0.10 ‡ | 0.38 ± 0.14 §,† | 0.45 ± 0.15 † |
† P < .05 versus age < 40 years.
‡ P < .05 versus age 40 to 59 years.
Circumferential Endocardial Mechanics
The average endocardial circumferential strain was −28 ± 4%, with a large and significant apical-to-basal gradient (−32 ± 6% vs −24 ± 4% at the apex and base, respectively; Table 3 ). Here again, basal inferior and inferior septal segments demonstrated the lowest strain (−22 ± 5%). Women had mildly but significantly lower systolic strain values, and larger reductions were observed in SR S and SR E, with an unchanged SR E/S ratio. With older age, systolic strain and SR S increased, resulting in a significant decrease in the SR E/S ratio, similar to its longitudinal value. SR A was similar in all the subgroups analyzed.
| By gender | By age (y) | |||||
|---|---|---|---|---|---|---|
| Variable | All patients ( n = 120) | Men ( n = 66) | Women ( n = 54) | <40 ( n = 62) | 40–59 ( n = 37) | >60 ( n = 21) |
| Strain (%) | −27.9 ± 4.0 | −28.3 ± 4.2 | −27.2 ± 3.7 | −26.9 ± 3.7 | −27.9 ± 4.2 | −31.2 ± 4.3 †,‡ |
| Base | −24.4 ± 4.1 | −24.4 ± 4.4 | −24.3 ± 3.8 | −24.0 ± 3.9 | −24.6 ± 3.6 | −26.1 ± 5.4 |
| Mid | −26.2 ± 4.6 | −26.5 ± 4.9 | −25.9 ± 4.4 | −25.3 ± 3.6 | −25.4 ± 4.7 | −30.6 ± 5.1 †,‡ |
| Apex | −32.4 ± 6.2 § | −33.5 ± 6.2 § | −31.2 ± 5.8 ∗,§ | −30.9 ± 5.7 § | −33.3 ± 6.5 † | −35.9 ± 6.2 ‡,§ |
| Systolic SR (sec −1 ) | −1.66 ± 0.33 | −1.71 ± 0.36 | −1.58 ± 0.28 ∗ | −1.58 ± 0.28 | −1.67 ± 0.34 | −1.90 ± 0.39 †,‡ |
| Base | −1.40 ± 0.27 | −1.42 ± 0.29 | −1.38 ± 0.24 | −1.38 ± 0.26 | −1.38 ± 0.26 | −1.50 ± 0.31 |
| Mid | −1.50 ± 0.33 | −1.55 ± 0.5 | −1.38 ± 0.25 ∗ | −1.45 ± 0.27 | −1.45 ± 0.33 | −1.78 ± 0.38 †,‡ |
| Apex | −2.01 ± 0.54 § | −2.12 ± 0.56 § | −1.82 ± 0.44 ∗,§ | −1.88 ± 0.44 § | −2.12 ± 0.62 †,§ | −2.27 ± 0.61 †,§ |
| Early diastolic SR (sec −1 ) | 1.66 ± 0.34 | 1.71 ± 0.37 | 1.57 ± 0.28 ∗ | 1.62 ± 0.3 | 1.72 ± 0.41 | 1.74 ± 0.46 |
| Base | 1.34 ± 0.29 | 1.38 ± 0.31 | 1.30 ± 0.27 | 1.34 ± 0.27 | 1.36 ± 0.32 | 1.30 ± 0.31 |
| Mid | 1.50 ± 0.36 | 1.56 ± 0.35 | 1.44 ± 0.29 | 1.46 ± 0.3 | 1.52 ± 0.46 | 1.64 ± 0.39 |
| Apex | 2.09 ± 0.61 § | 2.16 ± 0.58 ‡ | 1.83 ± 0.44 ∗,§ | 2.01 ± 0.52 § | 2.20 ± 0.73 § | 2.09 ± 0.57 § |
| SR E/S ratio | 1.01 ± 0.12 | 0.99 ± 0.13 | 1.02 ± 0.12 | 1.03 ± 0.11 | 1.03 ± 0.14 | 0.90 ± 0.09 †,‡ |
| Late diastolic SR (sec −1 ) | 0.42 ± 0.16 | 0.40 ± 0.15 | 0.46 ± 0.16 | 0.36 ± 0.13 | 0.45 ± 0.13 † | 0.56 ± 0.31 †,‡ |
| Base | 0.42 ± 0.19 | 0.41 ± 0.17 | 0.45 ± 0.19 | 0.38 ± 0.17 | 0.43 ± 0.17 | 0.55 ± 0.19 †,‡ |
| Mid | 0.39 ± 0.15 | 0.37 ± 0.15 | 0.44 ± 0.19 ∗ | 0.34 ± 0.16 | 0.41 ± 0.15 † | 0.52 ± 0.18 †,‡ |
| Apex | 0.46 ± 0.22 | 0.44 ± 0.20 | 0.49 ± 0.24 | 0.37 ± 0.16 | 0.52 ± 0.23 † | 0.57 ± 0.24 † |
† P < .05 versus age < 40 years.
‡ P < .05 versus age 40 to 59 years.
Circumferential Epicardial Mechanics
Epicardial strain was about 40% lower than endocardial circumferential strain, averaging 11 ± 2% ( Table 4 ). There were no differences related to gender. Epicardial strain and SR followed the endocardial pattern of changes that were not statistically significant.
| By gender | By age (y) | |||||
|---|---|---|---|---|---|---|
| Variable | All patients ( n = 120) | Men ( n = 66) | Women ( n = 54) | <40 ( n = 62) | 40–59 ( n = 37) | >60 ( n = 21) |
| Strain (%) | −11.2 ± 2.3 | −11.2 ± 2.5 | −11.1 ± 1.9 | −11.6 ± 2.2 | −10.9 ± 2.2 | −10.6 ± 2.5 |
| Base | −11.3 ± 2.9 | −11.2 ± 3.1 | −11.3 ± 2.8 | −11.9 ± 2.9 | −10.7 ± 2.8 | −10.5 ± 2.9 |
| Mid | −10.6 ± 3.0 | −10.6 ± 3.1 | −10.5 ± 3.0 | −11.0 ± 3 | −9.8 ± 2.9 | −10.6 ± 3.4 |
| Apex | −11.8 ± 3.4 | −12.1 ± 3.6 | −11.5 ± 3.1 | −11.9 ± 3 | −12.3 ± 4 § | −10.7 ± 3.0 |
| Systolic SR (sec −1 ) | −0.62 ± 0.12 | −0.64 ± 0.14 | −0.59 ± 0.1 ∗ | −0.65 ± 0.12 | −0.60 ± 0.13 | −0.52 ± 0.12 †,‡ |
| Base | −0.62 ± 0.16 | −0.63 ± 0.17 | −0.60 ± 0.14 | −0.65 ± 0.16 | −0.57 ± 0.15 † | −0.57 ± 0.14 |
| Mid | −0.58 ± 0.16 | −0.59 ± 0.18 | −0.57 ± 0.14 | −0.61 ± 0.15 | −0.55 ± 0.15 | −0.56 ± 0.19 |
| Apex | −0.66 ± 0.19 | −0.70 ± 0.20 § | −0.62 ± 0.17 ∗ | −0.68 ± 0.17 | −0.70 ± 0.22 ‡ | −0.57 ± 0.17 |
| Early diastolic SR (sec −1 ) | 0.60 ± 0.13 | 0.61 ± 0.14 | 0.62 ± 0.12 | 0.63 ± 0.12 | 0.59 ± 0.13 | 0.55 ± 0.15 |
| Base | 0.61 ± 0.17 | 0.62 ± 0.18 | 0.60 ± 0.17 | 0.63 ± 0.17 | 0.61 ± 0.18 | 0.52 ± 0.15 |
| Mid | 0.57 ± 0.16 | 0.57 ± 0.18 | 0.57 ± 0.15 | 0.61 ± 0.16 | 0.54 ± 0.16 | 0.52 ± 0.16 |
| Apex | 0.63 ± 0.21 | 0.64 ± 0.20 | 0.62 ± 0.22 | 0.65 ± 0.18 | 0.66 ± 0.26 | 0.52 ± 0.16 †,‡ |
| SR E/S ratio | 0.97 ± 0.12 | 0.94 ± 0.12 | 1.02 ± 0.12 | 0.98 ± 0.11 | 0.97 ± 0.12 | 0.92 ± 0.11 †,‡ |
| Late diastolic SR (sec −1 ) | 0.20 ± 0.07 | 0.20 ± 0.15 | 0.21 ± 0.13 | 0.18 ± 0.05 | 0.23 ± 0.09 † | 0.22 ± 0.05 † |
| Base | 0.19 ± 0.08 | 0.19 ± 0.09 | 0.20 ± 0.07 | 0.20 ± 0.09 | 0.17 ± 0.07 | 0.21 ± 0.08 |
| Mid | 0.19 ± 0.09 | 0.18 ± 0.1 | 0.19 ± 0.07 | 0.16 ± 0.06 | 0.20 ± 0.11 † | 0.23 ± 0.07 † |
| Apex | 0.22 ± 0.14 § | 0.22 ± 0.14 | 0.24 ± 0.13 § | 0.18 ± 0.06 | 0.30 ± 0.19 †,§ | 0.21 ± 0.11 ‡ |
† P < .05 versus age < 40 years.
‡ P < .05 versus age 40 to 59 years.
Radial Mechanics
The average radial strain was 30 ± 7.5% and demonstrated a reversed apical-to-basal gradient (26 ± 10% vs 32 ± 12%, apical and basal, respectively; Table 5 ). The only other significant change was a decrease in the SR E/S ratio in the oldest subgroup, again similar to its longitudinal and circumferential values.
| By gender | By age (y) | |||||
|---|---|---|---|---|---|---|
| Variable | All patients ( n = 120) | Men ( n = 66) | Women ( n = 54) | <40 ( n = 62) | 40–59 ( n = 37) | >60 ( n = 21) |
| Strain (%) | 30.0 ± 7.5 | 29.9 ± 7.6 | 30.2 ± 7.7 | 30.3 ± 8 | 29.4 ± 6.9 | 30.4 ± 7.6 |
| Base | 31.7 ± 11.6 | 31.4 ± 10.8 | 31.7 ± 12.1 | 31.6 ± 11.2 | 32.2 ± 13.5 | 29.8 ± 7.4 |
| Mid | 33.4 ± 10.5 | 32.9 ± 10.2 | 34.7 ± 11.5 | 33.6 ± 11 | 31.0 ± 9.0 | 38.7 ± 11.6 ‡ |
| Apex | 25.4 ± 9.8 § | 26.3 ± 10.3 § | 24.5 ± 9.3 § | 26.5 ± 10.8 ‡ | 24.4 ± 9.1 § | 24.0 ± 7.3 § |
| Systolic SR (sec −1 ) | 1.33 ± 0.28 | 1.36 ± 0.28 | 1.30 ± 0.29 | 1.33 ± 0.28 | 1.35 ± 0.27 | 1.30 ± 0.31 |
| Base | 1.43 ± 0.44 | 1.42 ± 0.47 | 1.43 ± 0.41 | 1.42 ± 0.42 | 1.45 ± 0.54 | 1.40 ± 0.31 |
| Mid | 1.43 ± 0.41 | 1.46 ± 0.37 | 1.40 ± 0.47 | 1.45 ± 0.39 | 1.40 ± 0.32 | 1.43 ± 0.62 |
| Apex | 1.18 ± 0.38 § | 1.24 ± 0.39 § | 1.11 ± 0.36 § | 1.16 ± 0.23 ‡ | 1.21 ± 0.33 § | 1.17 ± 0.39 § |
| Early diastolic SR (sec −1 ) | −1.29 ± 0.29 | −1.32 ± 0.30 | −1.26 ± 0.28 | −1.32 ± 0.31 | −1.31 ± 0.28 | −1.18 ± 0.22 †,§ |
| Base | −1.29 ± 0.42 | −1.27 ± 0.40 | −1.32 ± 0.45 | −1.33 ± 0.37 | −1.30 ± 0.51 | −1.16 ± 0.36 |
| Mid | −1.37 ± 0.40 | −1.40 ± 0.44 | −1.34 ± 0.34 | −1.37 ± 0.47 | −1.39 ± 0.41 | −1.38 ± 0.31 |
| Apex | −1.23 ± 0.42 | −1.30 ± 0.44 | −1.15 ± 0.38 § | −1.28 ± 0.42 | −1.21 ± 0.35 | −1.05 ± 0.31 †,§ |
| SR E/S ratio | 0.97 ± 0.12 | 0.97 ± 0.15 | 0.98 ± 0.13 | 0.99 ± 0.11 | 0.96 ± 0.12 | 0.91 ± 0.11 † |
| Late diastolic SR (sec −1 ) | −0.51 ± 0.23 | −0.47 ± 0.21 | −0.56 ± 0.25 | −0.46 ± 0.22 | −0.53 ± 0.26 | −0.58 ± 0.21 |
| Base | −0.65 ± 0.37 | −0.62 ± 0.36 | −0.69 ± 0.37 | −0.58 ± 0.33 | −0.68 ± 0.45 | −078 ± 0.30 † |
| Mid | −0.49 ± 0.29 | −0.42 ± 0.32 | −0.57 ± 0.24 ∗ | −0.49 ± 0.27 | −0.46 ± 0.35 | −0.54 ± 0.27 |
| Apex | −0.41 ± 0.24 § | −0.39 ± 0.23 § | −0.43 ± 0.26 § | −0.36 ± 0.23 ‡ | −0.49 ± 0.26 § | −0.42 ± 0.21 †,§ |
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