Left Ventricular Posterior Wall Diameter Research Articles

Effectiveness of Angiotensin-Converting Enzyme Inhibitors in Pediatric Patients with Mid to Severe Aortic Valve Regurgitation

The long-term benefit of angiotensin-converting enzyme inhibitors in pediatric patients with aortic valve regurgitation is under consideration. Eighteen patients with mid to severe aortic valve regurgitation were retrospectively evaluated. Echocardiographic parameters (left ventricular end-diastolic diameter, shortening fraction, left ventricular posterior wall thickness, and grade of aortic valve regurgitation) were analyzed before and during therapy with angiotensin-converting enzyme inhibitors. Data are given as standard deviation scores (Z-scores) derived from body surface-adjusted normal values. Median (interquartile range) age at start of therapy was 8.4 (5.4 to 10.0) years, and total follow-up 2.3 (0.9 to 5.4) years. Left ventricular end-diastolic diameter increased from 3.6 (2.3 to 4.5) to 3.7 (2.4 to 4.8), and left ventricular posterior wall diameter decreased from 1.9 (1.1 to 3.0) to 1.1 (0.5 to 2.3). Grade of aortic valve regurgitation increased from 3.5 (2.3 to 4.0) to 4.0 (2.0 to 4.0), and shortening fraction decreased from 39% (34% to 43%) to 37% (34% to 42%). No significant effect of angiotensin-converting enzyme inhibitors on left ventricular dimensions or function was found in our population of patients with mid to severe aortic valve regurgitation. Angiotensin-converting enzyme inhibitors may not alter left ventricular overload in pediatric patients with aortic valve regurgitation.

Abstract 512: Cardiac Metabolic Adaptation during Chronic Exercise is Independent of PGC-1 Signaling

PGC-1alpha is a transcriptional coactivator that regulates gene expression of mitochondrial proteins and energy metabolic enzymes. In skeletal muscle, PGC-1alpha is induced by endurance training and thought to mediate the energy metabolic adaptation to exercise. We investigated the role of PGC-1alpha signaling in metabolic adaptation of the heart in response to exercise. Male Sprague Dawley rats were trained on treadmills for 10 weeks, resulting in increased left ventricular posterior wall diameter (1.84±0.13 vs. 2.35±0.15 mm, p<0.05), indicating physiological hypertrophy. Gene expression of PGC-1alpha and beta and their transcription factors (NRF1&2, ERRalpha, TFAm) was not different compared to controls. Similarly, expression of OXPHOS genes (Ndufa10, Uqcrc2, COXIV) was unchanged in treadmill-trained hearts. In accordance with gene expression, state 3 respiration of isolated mitochondria was not different from controls, using palmitoyl-carnitine, pyruvate, or glutamate as substrates (natomsO/min/mg protein: Control PC 121±30, Pyr 58±6, Glu 203±42). In contrast, mitochondrial state 3 respiration of the oxidative soleus muscle was tripled with all substrates (natomsO/min/mg protein: PC 150±18 vs. 453±125, Pyr 95±23 vs. 310±37, Glu 115±12 vs. 280±23, p<0.05). Since PGC-1alpha signaling may also regulate substrate oxidation, we investigated oxidation of fatty acids (FAO) and glucose (GO) in the isolated working rat heart using 0.4mM oleate and 5mM glucose. FAO was not different between groups (μmol/min/gdw: 0.99±0.07 vs. 0.92±1.10). While expression of PPARalpha was increased in treadmill trained rats (+49%, p<0.05), FAO genes were not differentially expressed (MCAD, LCAD, CPT1). GO was 40% lower in trained hearts (0.38±0.08 vs. 0.23±0.06 μmol/min/g dry, n.s.) and was accompanied by a trend towards increased PDK4 expression (+90%, p=0.059). The response to insulin was normal. Cardiac power in trained working hearts was also normal. We conclude that PGC-1 signaling may not mediate the cardiac hypertrophic response to exercise. In contrast to skeletal muscle, respiratory capacity is not increased in heart muscle after exercise. The metabolic phenotype of hypertrophied hearts in response to exercise is surprisingly normal.

Is Plasma Concentration of NT-Pro-Brain Natriuretic Peptide Associated with Left Ventricle Hypertrophy among Hemodialysis Patients?

OBJECTIVE To determine the association of plasma amino terminal pro-brain natriuretic peptide (NT-proBNP) level with left ventricle hypertrophy (LVH) among hemodialysis (HD) patients. METHODS We evaluated 65 patients on maintenance HD (28 women, 37 men) treated thrice weekly by low-flux hollow-fiber dialyzers for at least 6 months. Patients were divided into 2 groups according to whether they had LVH. NT-proBNP concentration of the patients was measured before and after the HD session. Cardiac parameters were detected by echocardiography after the day of HD after the session. RESULTS In group 1 were the 34 patients who were LVH(−) (19 women and 15 men) and in group 2 were the 31 patients who were LVH(+) (9 women and 22 men). Mean left ventricular posterior wall diameter (LVPWd) was 0.87 ± 0.16 cm in group 1 and 1.28 ± 0.16 cm in group 2 (p < .001). Men were predominant in group 2 (p = .029). The patients in group 2 were older than those in group 1 (p = .033). There were no significant differences between the groups in pre-HD and post-HD NT-proBNP levels (p = .163 and p = .327, respectively). We did not find any significant relationship between mean concentration of pre-HD NT-proBNP and LVPWd (r = 0.064, p = 0.612). A positive correlation was found between mean concentration of pre-HD NT-proBNP with age (r = 0.281, p = 0.023), MAP (r = 0.469, p < 0.001), and left atrial diameter (r = 0.322, p = 0.009). CONCLUSION Although increased serum levels of NT-proBNP in HD patients was found to be related to LAd, an indicator of hypervolemia, there was no association between NT-proBNP and LVH. Elevation of NT-proBNP is affected by multiple factors such as age, sex, arterial blood pressure, and dialyzer membrane.

Cardiac and vascular function in adolescents and young adults with type 1 diabetes.

The objective was to prospectively define cardiac and vascular function in adolescents and young adults with type 1 diabetes over a 3-year period. Thirty-three subjects with type 1 diabetes were studied in 1998, and 28 returned for follow-up in 2001. There were 28 controls without diabetes. All subjects underwent ultrasonography of the carotid artery to determine distensibility, compliance, and intimal-medial thickness, as well as echocardiographic studies, lipid profile, and measurement of hemoglobin A1c (HbA1c) levels and urinary albumin excretion rate. The diabetes group showed no significant change over the 3-year follow-up in lipid profile, HbA1c level, or albumin excretion rate, but a significant increase in body mass index. The diabetes and control groups were similar in age, lipid profile, and albumin excretion rate. Carotid artery distensibility and compliance in the diabetes group increased significantly from baseline to follow-up but did not differ significantly from controls. The intimal-medial thickness of the diabetes group remained unchanged over time but tended to be higher than controls. Echocardiographic studies showed no difference between the diabetes and control groups, but there was a small change in left ventricular posterior diastolic wall diameter in the subjects with diabetes over the 3-year period. There was an overall improvement in carotid function and no change in cardiac measures in subjects with diabetes over the 3 years, such that cardiac and vascular function were similar to those of controls. The reason for the improvement is uncertain, but may relate to the improvement of insulin sensitivity at the end of the pubertal growth period, rather than to changes in metabolic control or lipid profiles.

Maternal left ventricular mass and diastolic function during pregnancy.

To evaluate changes in left ventricular mass and diastolic function during normal pregnancy. This was a cross-sectional study of 125 pregnant women at 9-42 weeks of gestation and 19 non-pregnant female controls. Two-dimensional and M-mode echocardiography of the maternal left ventricle and left atrium was performed. During pregnancy left ventricular mass increased by 52%. There was an increase in left ventricular end-diastolic and end-systolic diameters (12% and 20%, respectively), left ventricular posterior wall diameter during diastole and systole (22% and 13%, respectively) and left intraventricular septum during diastole and systole (15% and 19%, respectively). Mitral valve A-wave maximum velocity increased during pregnancy by 19%, while mitral valve E-wave maximum velocity and the ratio of E-wave/A-wave velocities increased early in pregnancy by about 14% and 6%, respectively, with a subsequent decline to 4% and 10%, respectively, below non-pregnant levels. Left ventricular mass increases during pregnancy, while left ventricular diastolic function, as demonstrated by the changes in mitral valve flow velocities, increases in the first two trimesters but declines in the third trimester.

Echocardiographic dimensions and function in adults with primary growth hormone resistance (Laron Syndrome)

Patients with primary growth hormone (GH) resistance—Laron Syndrome (LS)—have no GH signal transmission, and thus, no generation of circulating insulin-like growth factor-I (IGF-I), and should serve as a unique model to explore the controversies concerning the long-term effect of GH/IGF-I deficiency on cardiac dimension and function. We assessed 8 patients with LS (4 men, 4 women) with a mean ( ± SD) age of 38 ± 7 years (range 22 to 45), and 8 aged-matched controls (4 men, 4 women) with a mean age of 38 ± 9 years (range 18 to 47) by echocardiography at rest, following exercise, and during dobutamine administration. Left ventricular (LV) septum, posterior wall, and end-diastolic diameter were significantly reduced in untreated patients with LS compared with the control group (p <0.05 for all). Systolic Doppler-derived parameters, including LV stroke volume, stroke index, cardiac output, and cardiac index, were significantly lower (p <0.05 for all) than in the control subjects, whereas LV diastolic Doppler parameters, including mitral valve waves E, A, E/A ratio, and E deceleration time, were similar in both groups. LV ejection fraction at rest as well as the stress-induced increment of the LV ejection fraction were similar in both groups. Our results show that untreated patients with long-term IGF-I deficiency have reduced cardiac dimensions and output but normal LV ejection fraction at rest and LV contractile reserve following stress.

Influence of humoral and neurohormonal factors on cardiovascular hypertrophy in untreated essential hypertensives.

In essential hypertension, cardiovascular structure is believed to be influenced by hormonal and by hemodynamic factors. The objective of the present study was, in essential hypertensives, to investigate the relationship between blood pressure (BP) level as well as circulating hormones on the one hand and cardiovascular structure on the other. Seventy-nine untreated essential hypertensives were examined by 24-h ambulatory BP monitoring, echocardiography, microscopy of subcutaneous resistance vessels and analyzes of plasma for angiotensin II (P-Ang II), aldosterone, atrial natriuretic factor and 24-h urinary excretion of catecholamines. Multiple regression analysis showed a statistically significant correlation between P-Ang II and the end diastolic interventricular septal diameter (IVSDd) (R = 0.32, P = .005) and a weak correlation between P-Ang II and the left ventricular posterior wall diameter (R = 0.22, P = .049). These correlations were closer in the subgroup of patients (N = 54) who had never received antihypertensive treatment (R = 0.42/0.32, respectively). A weak, though statistically significant, correlation was found between the catecholamine excretion and systolic BP (R = 0.26, P = .03). A statistically negative correlation existed between catecholamines and end-diastolic left ventricular internal diameter index (R = -0.36, P = .001). No significant relationship was found between hormonal levels and the tunica media structure of the resistance arteries. In conclusion, P-Ang II was in this study significantly correlated to IVSDd, but not to resistance artery structure. In essential hypertension a complex relationship exists between humoral and hemodynamic factors and cardiovascular remodeling.