Normal reference values of diastolic strain rate in healthy individuals: Chronological trends and the comparison according to genders

Evaluation of Intraoperative Left-Ventricular Diastolic Function by Myocardial Strain in On-Pump Coronary Artery Bypass Surgery

OBJECTIVES

Left ventricular (LV) diastolic function strongly predicts outcomes after cardiac surgery, but there is no consensus about appropriate intraoperative assessment. Recently, intraoperative diastolic strain-based measurements assessed by transesophageal echocardiography (TEE) have shown a strong correlation with LV relaxation, compliance, and filling, but there are no reports about evaluation through the entire perioperative period. Therefore, the authors describe the intraoperative course of this novel assessment technique in patients who underwent coronary artery bypass grafting, and compare it with conventional echocardiographic measures and common grading algorithms of LV diastolic dysfunction (LVDD).

DESIGN

Prospectively obtained data.

SETTING

A single university hospital.

PARTICIPANTS

Thirty adult patients scheduled for isolated on-pump coronary artery bypass grafting surgery with preoperative preserved left and right ventricular systolic function, without significant heart valve disease and pulmonary hypertension, and an uneventful intraoperative course were included.

INTERVENTIONS

Transesophageal echocardiography was performed after induction of anesthesia (T1), after termination of cardiopulmonary bypass (T2), and after sternal closure (T3). Echocardiographic evaluation was performed in stable hemodynamic conditions, in sinus rhythm or atrial pacing, and vasopressor support with norepinephrine ≤0.1 µg/kg/min.

MEASUREMENTS AND MAIN RESULTS

Strain-based measurements of peak longitudinal strain rate during isovolumetric relaxation (SR-IVR) and during early (SR-E) and late (SR-A) LV filling were assessed using EchoPAC v204 software (GE Vingmed Ultrasound AS, Norway). Evaluation of conventional echocardiographic parameters included transmitral Doppler measures of early (E) and late (A) LV filling, as well as lateral-tissue Doppler velocity assessed during early (e´) and late (a´) LV filling, tricuspid regurgitation, and left atrial dilatation. Evaluation and grading of LV diastolic function by myocardial strain was feasible in all included patients at all time points of assessment. Using conventional grading algorithms, however, a substantial number of patients could not be sufficiently graded, falling into an indeterminate zone and not reliably estimating LVDD (T1, 40%; T2, 33%; T3, 36%). There was significant impairment of LV diastolic function after bypass, as measured by SR-IVR (T1 v T2, 0.28 s-1 [IQR 0.23; 0.31) v 0.18 s-1 [IQR 0.14; 0.22]; p < 0.001), SR-E (T1 v T2, 0.95 ± 0.34 s-1v 1.28 ± 0.36 s-1; p < 0.001), and E/SR-IVR (T1 v T2, 2.3 ± 1.0 m v 4.5 ± 2.1 m; p < 0.001]. Conventional echocardiographic measures remained unchanged during the same period (E/A T1 v T2, 1.27 [IQR 0.94; 1.59] v 1.21 [IQR 1.03; 1.47] [p = 1] and E/e´ T1 v T2, 7.0 [IQR 5.3; 9.6] v 6.35 [IQR 5.7; 9.9] [p = 0.9]). There were no significant changes in the values of SR-IVR, SR-E, SR-A, E/SR-IVR, E/A, and E/e´ before and after sternal closure (T2 v T3).

CONCLUSION

Intraoperative assessment of strain-based measurements of LV diastolic function and strain-based LVDD grading was feasible in this group of selected patients, whereas conventional parameters failed to describe LVDD sufficiently in a substantial number of patients. Diastolic strain-based measurements showed impairment of LV relaxation and compliance after bypass, which was not detected by conventional echocardiographic parameters. Therefore, diastolic myocardial strain analysis might be more sensitive in detecting myocardial diastolic dysfunction by TEE in the perioperative setting, with its dynamic changes of loading conditions, and might provide valuable and additional information on the perioperative changes of LV diastolic function.

Normal Values and Reference Ranges for the Ratio of Transmitral Early Filling Velocity to Early Diastolic Strain Rate: The Copenhagen City Heart Study

BACKGROUND

The ratio of transmitral early filling velocity to early diastolic strain rate (E/e'sr) has recently emerged as a measure of left ventricular filling pressure. Reference values are needed for this new parameter for it to be used clinically.

METHODS

Healthy participants from a prospective general population study, the Fifth Copenhagen City Heart Study, were assessed to establish reference values for E/e'sr derived from two-dimensional speckle-tracking echocardiography. The prevalence of abnormal E/e'sr was assessed in participants with cardiovascular risk factors or specific diseases.

RESULTS

The population comprised 1,623 healthy participants (median age, 45; interquartile range, 32-56; 61% female). The upper reference limit for E/e'sr in the population was 79.6 cm. Following multivariable adjustment, male participants exhibited significantly higher E/e'sr than female participants (upper reference limit for male participants, 83.7 cm; for female participants, 76.5 cm). For both sexes, E/e'sr increased in a curvilinear fashion with age such that the largest increases in E/e'sr were observed in participants >45 years. In the entire CCHS5 population with E/e'sr available (n = 3,902), increasing age, body mass index, systolic blood pressure, male sex, estimated glomerular filtration rate, and diabetes were associated with E/e'sr (all P < .05). Total cholesterol was associated with a less steep increase in E/e'sr. Abnormal E/e'sr was seldomly observed in participants with normal diastolic function but became more frequent in participants with increasing grades of diastolic dysfunction (normal, mild, moderate, severe [abnormal E/e'sr for each grade: 4.4% vs 20.0% vs 16.2% vs 55.6%, respectively]).

CONCLUSION

The E/e'sr differs between sexes and is age dependent such that E/e'sr increases with advancing age. Therefore, we established sex- and age-stratified reference values for E/e'sr.

Normative values of non-invasively assessed RV function and pulmonary circulation coupling for pre-participation screening derived from 497 male elite athletes

BACKGROUND

Reference values for right ventricular function and pulmonary circulation coupling were recently established for the general population. However, normative values for elite athletes are missing, even though exercise-related right ventricular enlargement is frequent in competitive athletes.

METHODS

We examined 497 healthy male elite athletes (age 26.1 ± 5.2 years) of mixed sports with a standardized transthoracic echocardiographic examination. Tricuspid annular plane excursion (TAPSE) and systolic pulmonary artery pressure (SPAP) were measured. Pulmonary circulation coupling was calculated as TAPSE/SPAP ratio. Two age groups were defined (18-29 years and 30-39 years) and associations of clinical parameters with the TAPSE/SPAP ratio were determined and compared for each group.

RESULTS

Athletes aged 18-29 (n = 349, 23.8 ± 3.5 years) displayed a significantly lower TAPSE/SPAP ratio (1.23 ± 0.3 vs. 1.31 ± 0.33 mm/mmHg, p = 0.039), TAPSE/SPAP to body surface area (BSA) ratio (0.56 ± 0.14 vs. 0.6 ± 0.16 mm*m2/mmHg, p = 0.017), diastolic blood pressure (75.6 ± 7.9 vs. 78.8 ± 10.7 mmHg, p < 0.001), septal wall thickness (10.2 ± 1.1 vs. 10.7 ± 1.1 mm, p = 0.013) and left atrial volume index (27.5 ± 4.5 vs. 30.8 ± 4.1 ml/m2, p < 0.001), but a higher SPAP (24.2 ± 4.5 vs. 23.2 ± 4.4 mmHg, p = 0.035) compared to athletes aged 30-39 (n = 148, 33.1 ± 3.4 years). TAPSE was not different between the age groups. The TAPSE/SPAP ratio was positively correlated with left ventricular stroke volume (r = 0.133, p = 0.018) and training amount per week (r = 0.154, p = 0.001) and negatively correlated with E/E' lat. (r = -0.152, p = 0.005).

CONCLUSION

The reference values for pulmonary circulation coupling determined in this study could be used to interpret and distinguish physiological from pathological cardiac remodeling in male elite athletes.

The effect of kidney transplantation on left ventricular remodeling and global diastolic strain rate in end-stage renal disease

BACKGROUND

Diastolic dysfunction is an early marker of cardiac pathology in end-stage kidney disease (ESKD) patients. The ratio of transmitral filling velocity (E) to early diastolic strain rate (E/e'sr) is a novel non-invasive marker of early left ventricular (LV) filling pressure obtained using two-dimensional speckle tracking echocardiography (2DSTE).

METHODS

In a prospective cohort of kidney transplant (KTX) recipients with echocardiograms performed pre-transplant we obtained repeat echocardiograms at 6 months following transplant. All echocardiograms were analyzed using 2DSTE where E/e'sr and global longitudinal strain were obtained. Paired tests were used to assess changes to cardiac structure and function following KTX.

RESULTS

A total of 33 patients were included in the study (mean age was 46.6 ± 13.7 years and 42% were males). The primary causes of ESKD in the cohort were glomerular disease (33%), hypertension (30%), and polycystic kidney disease (12%). The median (IQR) time spent on dialysis was 5.4 years [2.9, 7.7 years]. A reverse remodeling of the LV was observed following KTX as LV mass decreased (189.2 ± 57.5 g vs 171.1 ± 56.8 g, P = 0.014). LV filling pressure decreased as assessed by E/e'sr (103.7 ± 51.1 cm vs 72.6 ± 35.5 cm, P = 0.009). E to early diastolic mitral annular tissue velocity (E/e') did not change following KTX (9.9 ± 4.5 vs 10.3 ± 4.1, P = 0.54). Additionally, both LV internal diastolic and systolic diameter decreased significantly.

CONCLUSION

Reverse cardiac remodeling following KTX was observed as improvements in LV mass and LV dimensions. LV filling pressure improved as assessed by E/e'sr decreased following KTX, whereas E/e' did not change.

Normal Reference Values for Left Atrial Strain and Its Determinants from a Large Korean Multicenter Registry

BACKGROUND

Left atrial (LA) strain is a novel parameter of LA function. However, its reference value has not been established, and the determining factors for LA strain remain elusive. We aimed to present LA strain with reservoir, conduit, and contractile components and associated parameters in a large-sized group of healthy individuals.

METHODS

The present study was from a prospective multicenter registry in South Korea. Subjects who had no history of cardiovascular disease with adequate images were eligible for inclusion. LA reservoir, conduit, and contractile strains (LAS_RES, LAS_CD and LAS_CT, respectively) were measured. Left ventricular global longitudinal strain (LV GLS) and early and late diastolic strain rates (DSR_e and DSR_a, respectively) were also evaluated.

RESULTS

Among a total of 324 subjects (mean age: 49 ± 16 years, 167 females), the mean LAS_RES, LAS_CD, and LAS_CT values were 35.9% ± 10.6%, 21.9% ± 9.3%, and 13.9% ± 3.6%, respectively. Mean LV GLS was -20.4% ± 2.2%, and mean DSR_e and DSR_a were 1.6 ± 0.4 s^-1 and 0.8 ± 0.3 s^-1, respectively. With aging, LAS_RES and LAS_CD showed significant decreases. Factors showing independent associations with LAS_RES were age (B = -0.425, p < 0.001), DSR_e (B = 4.706, p = 0.001), and LV GLS (B = -1.081, p < 0.001). Age (B = -0.319, p < 0.001), DSR_e (B = 4.140, p = 0.002), DSR_a (B = -3.409, p = 0.018), and LV GLS (B = -0.783, p < 0.001) showed associations with LAS_CD. With LAS_CT, only DSR_a showed a correlation (R = 0.277, p < 0.001).

CONCLUSIONS

We presented LA strain in a large-sized group of healthy subjects. Age is a significant determinant of LA function. Associations of LA strain with diastolic strain rates and LV GLS reflect cardiac mechanics.

Diastolic strain imaging: a new non-invasive tool to detect subclinical myocardial dysfunction in early cardiac allograft rejection

Acute cellular rejection (ACR) remains a significant contributor to increased morbidity and mortality in heart transplant recipients. Early detection of ACR by non-invasive imaging is of potential clinical benefit. This study sought to investigate the use of non-invasive early global diastolic strain rate (GDSRe) and global longitudinal strain (GLS) in the detection of biopsy proven ACR. We retrospectively analysed 31 heart transplant patients (Mean age 52 ± 14 years) with biopsy proven ACR who underwent serial transthoracic echocardiographic examination and 2D strain analysis. Traditional echocardiographic systolic and diastolic parameters and novel systolic and diastolic strain imaging were measured during (1) early rejection free period (0R); (2) pre-rejection period (pre-1R); and (3) grade 1R acute cellular rejection (1R-ACR). GDSRe was significantly reduced (p = 0.0001) during the pre-rejection period (pre-1R) (0.74/s) when compared with 0R (0.97/s). GLS was only significantly reduced during 1R-ACR (17.7%), p = 0.001 but could not detect pre-1R (19.9%). Global diastolic strain rate at isovolumic relaxation showed no significant differences between any of the rejection periods. Traditional systolic and diastolic indices showed no significant differences. In conclusion, early global diastolic strain rate is the most sensitive parameter to detect subclinical myocardial dysfunction during early periods of pre-1R prior to biopsy confirmed 1R-ACR. GDSRe is a potential new tool for non-invasive screening of early post-transplant cardiac allograft rejection.