Mean Isovolumic Relaxation Time Research Articles

English

BACKGROUND Diabetes mellitus (DM) single-handedly accounts for 75 – 90 % of excess coronary artery disease (CAD) risk seen in persons suffering from it and it also enhances and amplifies the effects of other traditional cardiovascular risk factors. After adjusting for concomitant risk factors such as hypertension and hyperlipidemia, there still remains an excess risk for cardiovascular disease (CVD) in people with diabetics. In this study, we wanted to evaluate left ventricular (LV) systolic and diastolic dysfunction in normotensive diabetic patients. METHODS A cross sectional comparative study was performed from January 2016 to September 2017 on 50 diabetics and 50 age and sex matched healthy controls. Adult patients of both sexes with diabetes mellitus who are normotensive were included as cases. Patients with known heart disease, chronic kidney disease, thyroid disorders were excluded from the study. 2D transthoracic echocardiogram (ECHO) with M mode was used for assessing systolic and diastolic function. RESULTS Mean ejection fraction was lower in patients group (59.76) as compared to control group (64.74) with 8 % of cases with a value of< 50 %. Fractional shortening was also lower in patients (29.14) compared to controls (34.86) with 12 % patients having a value of < 25 %. E/A ratio was 1.12 in patients when compared to 1.36 in controls with 32 % of patients having value < 1. Mean isovolumic relaxation time was 96.52 in patients when compared to 87.42 in controls with 24 % patients having value > 100 msec. CONCLUSIONS Normotensive diabetics are prone to left ventricular dysfunction. Diastolic dysfunction is more common than systolic dysfunction. KEYWORDS Diabetes Mellitus, Systolic Dysfunction, Diastolic Dysfunction, Cardiovascular Disease

Pulsed tissue Doppler imaging of the left ventricular septal mitral annulus in healthy dogs

This study evaluated pulsed TDI variables including the isovolumic time interval and duration of the major wave in a population of large healthy dogs. Longitudinal myocardial motion at the septal mitral annulus was evaluated with pulsed TDI in 45 healthy adult dogs. Maximal myocardial velocities, isovolumic time intervals, and duration of the myocardial waves were measured. The correlation between time intervals and velocity variables was also investigated. The mean maximal systolic velocity was 6.92 ± 1.78 cm/sec, the mean early diastolic velocity (Em) was 6.58 ± 1.81 cm/sec, the mean late diastolic velocity (Am) was 5.10 ± 2.00 cm/sec, the mean isovolumic contraction time (IVCT) was 53.61 ± 95.13 msec, and the mean isovolumic relaxation time (IVRT) was 26.74 ± 57.24 msec. The early diastolic mitral inflow velocity (E)/Em ratio was 10.94 ± 3.27 while the Em/Am ratio was 1.40 ± 0.40. There was a negative correlation between Am duration and Am amplitude, and a positive correlation between the IVRT and Em/Am ratio (p < 0.05). The normal LV parameter using pulsed TDI method could be used as the reference range for identifying myocardial dysfunction in dogs.

Acute and chronic hypothyroidism are associated with similar left ventricular diastolic dysfunction relative to the euthyroid state: results of doppler echocardiographic comparisons.

How the duration of hypothyroidism affects left ventricular diastolic function is not well-characterized. We sought to compare left ventricular diastolic function in acutely vs chronically hypothyroid patients vs euthyroid controls, and within individuals while on vs off T4. We prospectively performed such comparisons measuring pulsed-wave and color M-mode Doppler echocardiographic variables: early or late mitral peak velocities (E wave or A wave, respectively), E wave/A wave ratio, E wave deceleration time, isovolumic relaxation time (IVRT), mitral flow propagation velocity (Vp), E wave/Vp ratio. Subjects comprised the acute HYPO group, 10 patients undergoing T4 withdrawal ≥ 6 months post-primary treatment for differentiated thyroid cancer (DTC); the chronic HYPO group, 23 treatment-naïve Hashimoto thyroiditis patients; and 21 healthy euthyroid controls. Subjects were adults aged ≤ 60 yr, predominantly female, with sinus rhythm; exclusion criteria were cardiovascular or thyroid disorder besides DTC (Hashimoto thyroiditis) in acute (chronic) HYPO patients or medication (besides thyroid hormone) affecting cardiac or thyroid function. Mean IVRT was significantly delayed and mean Vp, significantly slowed in both HYPO groups vs controls (p<0.0005), but did not differ between HYPO groups. These variables also were significantly impaired (p<0.05) within individuals when off vs on T4 (no.=8 acute, 10 chronic HYPO patients). Both HYPO groups had elevated mean E wave/Vp ratios vs controls, but the elevation reached significance (p<0.05) only in the larger chronic HYPO group. Left ventricular diastolic dysfunction is largely similar in acutely or chronically hypothyroid patients off T4 vs healthy controls or the same patients on T4.

Metformin is associated with improved left ventricular diastolic function measured by tissue Doppler imaging in patients with diabetes

To examine the association between selected glucose-lowering medications and left ventricular (LV) diastolic function in patients with diabetes. Retrospective cohort study (years 2005-2008). Echocardiograms of 242 patients with diabetes undergoing coronary angiography were analyzed. All patients had an LV ejection fraction (LVEF) ≥20% and were without atrial fibrillation, bundle branch block, valvular disease, or cardiac pacemaker. Patients were grouped according to the use of metformin (n=56), sulfonylureas (n=43), insulin (n=61), and combination treatment (n=82). Mean age (66±10 years) and mean LVEF (45±11%) were similar across the groups. Mean isovolumic relaxation time (IVRT) was 66±31, 79±42, 69±23, and 66±29 ms in metformin, sulfonylureas, insulin, and combination treatment groups respectively (P=0.4). Mean early diastolic longitudinal tissue velocity (e') was 5.3±1.6, 4.6±1.6, 5.3±1.8, and 5.4±1.7 cm/s in metformin, sulfonylureas, insulin, and combination treatment groups (P=0.04). In adjusted linear regression models, the use of metformin was associated with a shorter IVRT (parameter estimate -9.9 ms, P=0.049) and higher e' (parameter estimate +0.52 cm/s, P=0.03), compared with no use of metformin. The effects of metformin were not altered by concomitant use of sulfonylureas or insulin (P for interactions >0.4). The use of metformin is associated with improved LV relaxation, as compared with no use of metformin.

Echocardiographic evaluation of systolic and diastolic heart function in patients suffering from beta-thalassemia major aged 5-10 years at the Zahedan Research Center for

Cardiac complications are the major cause of morbidity and mortality in beta-thalassemia major. The aim of the study was to evaluate right (RV) and left (LV) ventricular systolic and diastolic functions using myocardial performance index in young, asymptomatic children suffering from thalassemia major, for early detection of cardiac function impairment, preventing further cardiac damage by modifying disease progression and treatment. A case-controlled, cross-sectional study involving 80 patients suffering from beta- thalassemia major and 80 children adjusted in terms of age and sex served as a control group were studied in Research Center for Children and Adolescent Health Zahedan. The relevant echocardiographic parameters were measured in both subject groups: myocardial performance index (MPI), isovolumic relaxation time (IRT), isovolumic contraction time (ICT), pre-ejection period (PEP), ejection time (ET), PEP/ET ratio, deceleration time (DT) and acceleration time (AT). Data were analyzed by unpaired Student t test. The left ventricular mean IRT in the patient group was 114+/-21 and in the control group 94+/-10 msec (p=0.05). The mean MPI (LV) in the patient group was 0.58+/-0.18 and in the control group 0.41+/-0.08 (p=0.05). The mean ET (LV) in the patient group was 237+/-36 msec and in the control group 266+/-25 msec (p=0.05). The mean ET (RV) in the patient group was 237+/-39 msec and in the control group 261+/-36 msec (p=0.05). There is an early systolic and diastolic dysfunction in children younger than 10 years with beta-thalassemia major. Even in young asymptomatic children with beta-thalassemia major, serial echocardiography seems warranted in order to adjust cardioprotective therapy.

Left Ventricular Diastolic Function in Trained Male Weightlifters at Rest and During Isometric Exercise

Individuals involved in intense resistance training present with increased absolute left ventricular (LV) wall thickness and mass and show good systolic responses to isometric exercise. There is no consensus regarding diastolic features and no available information regarding diastolic function in athletes during isometric exertion itself. Therefore, the main aim of this study was to assess diastolic LV function at baseline and during exercise in athletes. The population consisted of 96 men (mean age 29 +/- 7 years): 48 weight lifters who trained for 15 to 20 hours/week and 48 sedentary men. All weight lifters had been active for >6 years, including the 6 months before the study. Ultrasound was performed using a commercially available Doppler echocardiographic system. Isometric exercise was performed in the supine position using a standard 2-hand bar dynamometer. The man end-diastolic volumes at rest were 97 +/- 6 ml in sedentary subjects and 101 +/- 5 ml in weight lifters, increasing to 100 +/- 6 and 118 +/- 11 ml during exercise (p = 0.06 and p <0.01, respectively). End-systolic volumes at rest were similar in the 2 groups, showing significantly greater reductions during exercise in the weight lifters. The mean absolute LV mass was 167 +/- 30 g in sedentary subjects and 202 +/- 32 g in weight lifters (p <0.0001). The mean stroke volume increased from 65 +/- 7 to 86 +/- 7 ml in sedentary subjects and from 70 +/- 6 to 107 +/- 11 ml in weight lifters (intergroup significance p = 0.05 and p <0.01, respectively). A similar pattern of response was documented for the ejection fraction (i.e., significantly greater increases during exercise in weight lifters). Regarding diastolic indexes, in the weight lifters, the mean peak early velocity at rest was 68 +/- 7 cm/s, the mean acceleration rate was 1,242 +/- 176 cm/s/s, and the mean deceleration rate was 414 +/- 44 cm/s/s. All these values were significantly higher than in sedentary subjects, with further increases during exercise (p <0.0001). In weight lifters, the mean peak atrial velocity at rest was 37 +/- 6 cm/s, the mean acceleration time was 55 +/- 4 ms, the mean isovolumic relaxation time was 63 +/- 3 ms, and the mean deceleration time was 164 +/- 4 ms; these values were lower than in sedentary subjects (p <0.0001 for all). In conclusion, intense resistance training leads to enhanced LV diastolic function at rest and during isometric exercise despite the markedly increased LV mass.

Evaluation of Cardiac Global Function Using the Myocardial Performance Index by Tissue Doppler Echocardiography in Patients With Uremia

The purpose of this study was to assess global ventricular function in patients with uremia by means of the myocardial performance index (MPI) derived from tissue Doppler echocardiography. According to the left ventricular mass index and pericardial effusion, 45 patients with uremia were classified into 2 groups: a uremia group and a uremia with pericardial effusion group. To calculate left ventricular MPI (LVMPI) and right ventricular MPI (RVMPI) by tissue Doppler echocardiography, the isovolumic contraction time (ICT), isovolumic relaxation time (IRT), and ejection time (ET) were measured at different sites in the mitral and tricuspid annuli. The mean ICT and IRT were longer, the ET was shorter, and the LVMPI and RVMPI were higher in the 2 disease groups than in a control group, and the indices were higher in the uremia with pericardial effusion group than in the uremia group. The increase of the LVMPI was more obvious than that of the RVMPI. There was a significant difference in the mean LVMPI and RVMPI among the 3 groups (P<.01). The MPI was positively correlated with the IRT and the sum of the ICT and IRT and negatively correlated with the ET. Both left and right ventricular systolic and diastolic function are impaired in patients with uremia. The MPI could be measured by tissue Doppler echocardiography, and we suggest that this index provides a novel, noninvasive method for clinical research on global myocardial performance in patients with uremia.

Transforming growth factor beta and myocardial dysfunction following heart transplantation.

We analyzed the role of transforming growth factor-beta (TGF-beta), a fibrogenic cytokine, in the development of left ventricular diastolic dysfunction following heart transplantation. We studied 152 heart transplant recipients who had survived for at least 24 months. We compared histopathological findings (staining of endomyocardial biopsy specimens using Hematoxylin Eosin and polyclonal antibodies), left ventricular function (Doppler echocardiography) and clinical course (NYHA status). Patients are classified into group A (n=56 recipients) with immunohistochemical TGF-beta staining score >7 and group B (n=96 recipients) with a staining score <7. Doppler echocardiographic evaluation demonstrated greater impairment of left ventricular diastolic function in recipients with higher TGF-beta staining score. The average mitral deceleration time was 129+/-6 ms for recipients group A compared to 167+/-15 ms in group B. While the mean isovolumic relaxation time was 65+/-8 ms for patients in group A compared with 82+/-6 ms for recipients in group B (P=0.0004 and 0.005, respectively). Immunohistochemical scoring correlated inversely with both mitral deceleration and isovolumic relaxation times (r=-0.74, P=0.0004 and r=-0.66, P=0.004, respectively). Mean NYHA status was 2.7+/-1.3 for group A compared to 1.17+/-0.4 in group B was (P=0.002). Five years follow-up revealed persistent left ventricular diastolic impairment for recipients with higher immunohistochemical staining score. Mitral deceleration time and isovolumic relaxation time were 118+/-11 and 62+/-7 ms for group A compared to 156+/-12 and 80+/-5 ms for group B, P=0.006 and P=0.01, respectively. The actuarial development of subsequent coronary artery disease (> 50% stenosis) was 17 and 29% for recipients in group A compared to 4 and 6% for recipients in group B at 3 and 5 years follow-up, respectively (P=0.01 and P=0.005, respectively). TGF-beta expression in cardiac allografts is associated with impaired graft function and limited survival. The pathogenesis of diastolic dysfunction may be an aberrant repair process following rejection due to increased TGF-beta expression in transplant recipients.

Assessment of the severity of mitral regurgitation from the dynamics of retrograde flow.

Sixty four consecutive patients with isolated mitral regurgitation referred for Doppler echocardiography were divided into three groups: group 1, 20 patients with severe mitral regurgitation that required operation; group 2, 22 patients with severe left ventricular dysfunction and secondary mitral regurgitation; and group 3, 22 patients with mild to moderate mitral regurgitation that did not require valve operation. M mode and continuous wave Doppler traces with a simultaneous electrocardiogram and phonocardiogram were analysed to identify time intervals that could be used to distinguish patients who needed valve operation from those who did not. An interval of less than 55 ms between the aortic component of the second heart sound (A2) and the cessation of mitral retrograde flow was a powerful predictor that the patient required operation (sensitivity 100% and specificity 86%). The mean (SD) value of this variable in group 1 (40(15) ms) was significantly lower than in group 2 (90(35)ms) and group 3 (75(20)ms). Mean isovolumic relaxation time was less than normal in group 1 but did not differ significantly between groups. Deceleration of regurgitant velocity at end ejection was greater in group 1. The pressure drop from the left ventricle to the left atrium at A2 of less than 50% of the peak gradient also identified patients who needed valve operation (sensitivity 75% and specificity 68%). These findings may help to identify patients who require operation. They suggest that there are significant differences in the dynamics of flow velocities in patients with mitral regurgitation, possibly related to the relative resistances to retrograde and anterograde and anterograde flow.