Left ventricular hypertrophy: pathogenesis, detection, and prognosis

Regression of left ventricular hypertrophy with moexipril, an angiotensin-converting enzyme inhibitor, in hypertensive patients

Left ventricular hypertrophy (LVH) is a common complication of essential hypertension and an independent risk factor for the development of cardiovascular disease. Therefore, antihypertensive treatment should decrease blood pressure (BP) and reverse LVH. However, antihypertensive drugs have been shown to have different effects on LVH despite similar effects on BP reduction. Although lowering BP produces a beneficial effect on LVH per se, meta-analyses of clinical trials have indicated that angiotensin-converting enzyme (ACE) inhibitors decrease left ventricular mass (LVM) to a greater extent than do some other antihypertensives. The aim of this study was to evaluate the effect of a 24-week treatment with the ACE inhibitor moexipril (15 mg once daily) on the regression of LVH in hypertensive patients. This was a multicenter, international, single-blind, single-group, nonrandomized study. After a wash-out placebo period of 2 weeks, 15 mg moexipril once daily was administered for 24 weeks followed by a 2-week follow-up placebo period. Subjects with mild to moderate essential hypertension were screened; those with LVH [defined as an LVM indexed for body surface area (LVMIs) >111 g/m in men and LVMIs >106 g/m in women] were eligible to participate in this study. Echocardiograms were recorded on videotape and sent to a centralized laboratory for reading by 2 independent experts blinded for treatment, center, and visit; the mean values of these readings were calculated and used for analysis. Valid echocardiographic data were obtained from 72 patients (50 males, 22 females) with a mean age of 49 +/- 11 years. Analysis showed significant decrease of LVMIs (121 +/- 20 versus 103 +/- 17 g/m; P < 0.001) and BP (152 +/- 12/96 +/- 9 versus 140 +/- 13/86 +/- 9 mm Hg; P < 0.001) with moexipril. For patients who met LVMI inclusion criteria after centralized, blinded readings, the decrease from baseline in LVMIs was 23.4 g/m. The decrease in LVMIs was independent from the regression to the mean phenomenon as observed from the follow-up placebo period. Moexipril 15 mg once daily administered for 24 weeks resulted in a significant reversal of LVH in patients with essential hypertension. The result compares favorably with results previously obtained in trials of similar duration with other ACE inhibitors.

Atorvastatin improves peroxisome proliferator-activated receptor signaling in cardiac hypertrophy by preventing nuclear factor-kappa B activation

Nuclear factor (NF)-kappa B signaling pathway plays a pivotal role in cardiac hypertrophy. Although it has been reported that statins inhibit cardiac hypertrophy by reducing generation of reactive oxygen species, it is not yet known whether statins prevent NF-kappa B activation and whether this effect can be related to the reduction in the peroxisome proliferator-activated receptor (PPAR) pathway. In this study, we examined the role of atorvastatin on NF-kappa B activity and PPAR signaling in pressure overload-induced cardiac hypertrophy. Our findings indicate that atorvastatin inhibits cardiac hypertrophy and prevents the fall in the protein levels of PPAR alpha and PPAR beta/delta. Further, atorvastatin treatment avoided NF-kappa B activation during cardiac hypertrophy, reducing the protein-protein association between these PPAR subtypes and the p65 subunit of NF-kappa B. These findings indicate that negative cross-talk between NF-kappa B and PPARs may interfere with the transactivation capacity of the latter, leading to a fall in the expression of genes involved in fatty acid metabolism, and that these changes are prevented by statin treatment.

Sildenafil citrate increases myocardial cGMP content in rat heart, decreases its hypertrophic response to isoproterenol and decreases myocardial leak of creatine kinase and troponin T

BACKGROUND

Cardiac hypertrophy is a major risk factor for morbidity and mortality in a number of cardiovascular diseases. Consequently, the signaling pathways that inhibit cardiac hypertrophy are currently receiving much interest. Among them, nitric oxide (NO), signaling via cGMP and cGMP-dependent protein kinase I, has been recognized as a negative regulator of cardiac hypertrophy. The present study investigated the in-vivo effect of sildenafil as a phosphodiestrase-5A (PDE-5A) inhibitor on the hypertrophic response of rat heart to isoproterenol and the relation of this effect to the level of myocardial cGMP and integrity of the constitutive nitric oxide synthase (cNOS) activity.

RESULTS

The results showed that daily intraperitoneal administration of sildenafil per se for 10 days was without noticeable adverse effects on survival or myocardium. Conversely, daily subcutaneous administration of isoproterenol for 10 days caused significant myocardial hypertrophy, cell injury and decline in survival. When sildenafil was injected daily, one hour before isoproterenol, survival was significantly improved and the myocardium didn't show significant hypertrophy or cell injury. Interestingly, sildenafil was accompanied by significant rise in myocardial cGMP level, a parameter which was found in the present study to possess a significant negative correlation with cardiac hypertrophy and leak of cardiac troponin T into serum. At the same time, cGMP was found to possess a positive correlation with myocardial creatine kinase activity that reflects the efficiency of the energy utilization processes in the myocardium. However, in rats given Nomega-nitro-L-arginine (L-NNA) as a competitive inhibitor of cNOS, sildenafil failed to show any favorable effect on survival or the myocardial injury parameters used to assess isoproterenol-induced injury.

CONCLUSION

The present study suggests that increased cardiac cGMP level by sildenafil have a cardioprotective effect probably through acting as a post-receptor negative regulator of cardiac sympathetic responsiveness. Integrity of NOS function was an essential prerequisite for sildenafil's mediated cardioprotection encountered in the present study.

Hypertensive heart disease

Hypertensive heart disease encompasses anatomical changes and altered physiology of heart muscle, coronary arteries, and great vessels. Left ventricular hypertrophy is not only a target organ response to increased afterload, but is also the most potent cardiovascular risk factor. Regression of hypertrophy reduces morbidity and mortality. Heart failure may be present in the absence of a reduction of myocardial contractility. Ischemic heart disease occurs in the absence of epicardial coronary disease. Left atrial size and atrial fibrillation are associated. Potentially lethal ventricular arrhythmias and sudden cardiac death are more common in hypertensive patients. The relationship of aortic root size to blood pressure is weaker than expected; however, the relationship to aortic dissection is stronger. Careful attention and treatment of left ventricular hypertrophy, heart failure, ischemic heart disease, and atrial fibrillation will improve survival.

Impact of Body Mass Index on Markers of Left Ventricular Thickness and Mass Calculation: Results of a Pilot Analysis

Specific correlations between body mass index (BMI) and left ventricular (LV) thickness have been conflicting. Accordingly, we investigated if a particular correlation exists between BMI and echocardiographic markers of ventricular function.

METHODS

A total of 122 patients, referred for routine transthoracic echocardiography, were included in this prospective pilot study using a 3:1 randomization approach. Patient demographics were obtained using a questionnaire.

RESULTS

Group I consisted of 80 obese (BMI was >30 kg/m2), Group II of 16 overweight (BMI between 26 and 29 kg/m2), and Group III of 26 normal BMI (BMI < 25 kg/m2) individuals. No difference was found in left ventricular wall thickness, LV end-systolic cavity dimension, fractional shortening (FS), or pulmonary artery systolic pressure (PASP) among the groups. However, mean LV end-diastolic cavity dimension was greater in Group I (5.0 +/- 0.9 cm) than Group II (4.6 +/- 0.8 cm) or Group III (4.4 +/- 0.9 cm; P < 0.006). LV mass indexed to height(2.7) was also significantly larger in Group I (61 +/- 21) when compared to Group III (48 +/- 19; P < 0.001). Finally, left atrial diameter (4.3 +/- 0.7 cm) was also larger (3.8 +/- 0.6 and 3.6 +/- 0.7, respectively; P < 0.00001).

DISCUSSION

We found no correlation between BMI and LV wall thickness, FS, or PASP despite the high prevalence of diabetes and hypertension in obese individuals. However, obese individuals had an increased LV end-diastolic cavity dimension, LV mass/height(2.7), and left atrial diameter. These findings could represent early markers in the sequence of cardiac events occurring with obesity. A larger prospective study is needed to further define the sequence of cardiac abnormalities occurring with increasing BMI.

Carvedilol prevents cardiac hypertrophy and overexpression of hypoxia-inducible factor-1α and vascular endothelial growth factor in pressure-overloaded rat heart

The use of beta-blockers has emerged as a beneficial treatment for cardiac hypertrophy. Hypoxia-inducible factor-1alpha (HIF-1alpha) is tightly regulated in the ventricular myocardium. However, the expression of HIF-1alpha in cardiac hypertrophy due to pressure overload and after treatment with beta-blocker is little known. To evaluate the effect of carvedilol on both myocardial HIF-1alpha expression and cardiac hypertrophy, infra-renal aortic banding was performed for 4 weeks in adult Sprague-Dawley rats to induce cardiac hypertrophy. Carvedilol at 50 mg/kg body weight per day after surgery was given. Heart weight and the ratio of heart weight and body weight increased significantly after aortic banding for 4 weeks in the absence of drug treatment. Mean arterial pressure increased from 80 +/- 9 mmHg in the sham group to 94 +/-5 mmHg (p < 0.001) in the banding group. Echocardiography showed concentric hypertrophy after aortic banding. Mean arterial pressure decreased after treatment with carvedilol. The increased wall thickness and heart weight was reversed to normal by carvedilol. Western blot showed that HIF-1alpha, vascular endothelial growth factor (VEGF) and brain natriuretic peptide (BNP) proteins were up-regulated and nerve growth factor-beta (NGF-beta) down-regulated in the banding group. Treatment with valsartan, doxazosin, or N-acetylcysteine did not significantly affect HIF-1alpha and VEGF proteins expression in the banding groups. Real-time polymerase chain reaction showed that mRNA of HIF-1alpha, VEGF and BNP increased and mRNA of NGF-beta decreased in the banding group. Treatment with carvedilol reversed both protein and mRNA of HIF-1alpha, VEGF, BNP, and NGF-beta to the baseline values. Increased immunohistochemical labeling of HIF-1alpha, VEGF, and BNP in the ventricular myocardium was observed in the banding group and carvedilol again normalized the labeling. In conclusion, HIF-1alpha, VEGF, and BNP mRNA and protein expression were up-regulated, while NGF-beta mRNA and protein was downregulated in the rat model of pressure-overloaded cardiac hypertrophy. Treatment with carvedilol is associated with a reversal of abnormal regulation of HIF-1alpha, VEGF, BNP, and NGF-beta in the hypertrophic myocardium.

Nuclear factor-kappaB activation leads to down-regulation of fatty acid oxidation during cardiac hypertrophy

Little is known about the mechanisms responsible for the fall in fatty acid oxidation during the development of cardiac hypertrophy. We focused on the effects of nuclear factor (NF)-kappaB activation during cardiac hypertrophy on the activity of peroxisome proliferator-activated receptor (PPAR) beta/delta, which is the predominant PPAR subtype in cardiac cells and plays a prominent role in the regulation of cardiac lipid metabolism. Phenylephrine-induced cardiac hypertrophy in neonatal rat cardiomyocytes caused a reduction in the expression of pyruvate dehydrogenase kinase 4 (Pdk4), a target gene of PPARbeta/delta involved in fatty acid utilization, and a fall in palmitate oxidation that was reversed by NF-kappaB inhibitors. Lipopolysaccharide stimulation of NF-kappaB in embryonic rat heart-derived H9c2 myotubes, which only express PPARbeta/delta, caused both a reduction in Pdk4 expression and DNA binding activity of PPARbeta/delta to its response element, effects that were reversed by NF-kappaB inhibitors. Coimmunoprecipitation studies demonstrated that lipopolysaccharide strongly stimulated the physical interaction between the p65 subunit of NF-kappaB and PPARbeta/delta, providing an explanation for the reduced activity of PPARbeta/delta. Finally, we assessed whether this mechanism was present in vivo in pressure overload-induced cardiac hypertrophy. In hypertrophied hearts of banded rats the reduction in the expression of Pdk4 was accompanied by activation of NF-kappaB and enhanced interaction between p65 and PPARbeta/delta. These results indicate that NF-kappaB activation during cardiac hypertrophy down-regulates PPARbeta/delta activity, leading to a fall in fatty acid oxidation, through a mechanism that involves enhanced protein-protein interaction between the p65 subunit of NF-kappaB and PPARbeta/delta.

Plasma B-type natriuretic peptide reflects left ventricular hypertrophy and diastolic function in hypertension

BACKGROUND

Hypertension is associated with changes in concentrations of vasoactive peptides and procollagen propeptides, but their relationships with left ventricular hypertrophy and cardiac function are unclear.

METHODS

We measured plasma levels of atrial natriuretic peptide (ANP), its amino terminal propeptide (NT-proANP), B-type natriuretic peptide (BNP), endothelin-1 (ET-1), and serum levels of the aminoterminal propeptide of type I procollagen (PINP) and the aminoterminal propeptide of type III procollagen (PIIINP) and echocardiographic parameters in 97 patients with hypertension in the Anglo-Scandinavian Cardiac Outcomes Trial.

RESULTS

Median values (reference values) of the peptides were: ANP 11.2 (6.9-14.9) pmol/l, NT-proANP 351 (143-311) pmol/l, BNP 1.1 (0.4-7.2) pmol/l, ET-1 8.7 (1.2-5.0) pmol/l, PIIINP 2.8 (1.7-4.2) microg/l and PINP 29 (19-84) microg/l. Plasma BNP levels in patients with left ventricular hypertrophy (1.2 pmol/l) and patients with echocardiographic signs of diastolic dysfunction (1.5 pmol/l) were greater than those in patients without hypertrophy (0.7 pmol/l) and normal diastolic parameters (0.9 pmol/l) (p<0.05). BNP was the only biochemical parameter that independently predicted interventricular septal diastolic diameter (p<0.05), left ventricular mass index (p<0.01) and ratio of the velocity-time integrals of the E and A waves of the mitral inflow in a stepwise logistic regression analysis (p<0.05).

CONCLUSIONS

The results show that BNP reflects the remodelling process in hypertension.

Interaction between vascular dysfunction and cardiac mass increases the risk of cardiovascular outcomes in essential hypertension

AIMS

To investigate the additive prognostic impact of both forearm endothelial dysfunction and left ventricular mass (LVM) for future cardiovascular events.

METHODS AND RESULTS

We enrolled 324 Caucasian, never treated, hypertensive outpatients. Endothelial function, by intra-arterial infusion of acetylcholine (ACh), and echocardiographic LVM were investigated. Patients were divided into tertiles on the basis of their increase in ACh-stimulated forearm blood flow (FBF) and LVM indexed by body surface area (LVMI). Cardiovascular events assessed were: fatal and non-fatal myocardial infarction, fatal and non-fatal stroke, transient cerebral ischaemic attack, unstable angina, coronary revascularization procedures, and symptomatic aorto-iliac occlusive disease. During a mean follow-up of 45.2+/-23.6 months, there were 47 new cardiovascular events (3.8 events/100 patient-years). The event rate was 6.8, 2.8, and 1.6% in the tertiles of ACh-stimulated FBF (log-rank test, P=0.0009), and 1.4, 3.4, and 6.6% in the tertiles of LVMI (log-rank test, P=0.0002), respectively. Besides, a significant interaction was documented between FBF and LVMI. In fact, the cardiovascular risk increases up to 11.4% in patients with low FBF and high LVMI.

CONCLUSION

For the first time, we demonstrate that the co-existence of LVH and endothelial dysfunction in hypertensive patients increases significantly the risk of subsequent cardiovascular events.

How much echo left ventricular hypertrophy would be missed in diabetics by applying the Losartan Intervention For Endpoint Reduction electrocardiogram criteria to select patients for angiotensin receptor blockade?

OBJECTIVE

The Losartan Intervention For Endpoint Reduction (LIFE) study demonstrated a clear mortality benefit in treating hypertensive patients with electrocardiogram (ECG) evidence of left ventricular hypertrophy (LVH) with losartan rather than atenolol. Previous studies have also shown that identifying and treating echo LVH is associated with prognostic benefits in hypertensive subjects, and is independent of the presence of ECG LVH. We sought to determine how many cases of echo LVH would be missed by applying the ECG criteria for LVH used in the LIFE study.

DESIGN

A prospective study of 219 patients with type 2 diabetes recruited from the hospital diabetic clinic.

METHODS

Fifteen ECG criteria were assessed on each subject and compared with the presence or absence of LVH on echocardiography.

RESULTS

All the proposed ECG criteria are poor at identifying echo LVH in people with diabetes.

CONCLUSION

Using ECG LVH to select patients for angiotensin receptor blockade would lead to many diabetics with echo LVH missing out on the benefits of treatment. This assumes that the benefits seen in the LIFE study would also occur if the LIFE strategy were extended to echo LVH patients as well as to ECG LVH patients.

Additional impact of electrocardiographic over echocardiographic diagnosis of left ventricular hypertrophy for predicting the risk of ischemic stroke

BACKGROUND

Patients with left ventricular hypertrophy (LVH) have an increased risk of ischemic stroke. Although echocardiography is commonly used for the diagnosis of LVH, there is little information about the potential role of electrocardiography in providing additional prognostic information. The purpose of this study is to determine if electrocardiographically derived criteria for LVH provide additional prognostic value over echocardiography for predicting ischemic stroke in a multiethnic population.

METHODS

A population-based, case-control study was conducted in 177 patients who had had a first ischemic stroke and in 246 control patients matched for age, gender, and race or ethnicity. Left ventricular mass was measured by using 2-dimensional transthoracic echocardiography. Logistic regression analysis was performed to assess the risk of stroke associated with the presence of LVH diagnosed by electrocardiography (defined by 4 established criteria) after adjustment for the presence of other stroke risk factors and for echocardiographically determined LVH.

RESULTS

After adjustment for the presence of other established stroke risk factors, ECG-LVH was associated with ischemic stroke, using Sokolow-Lyon (odds ratio [OR] 2.12, 95% CI 1.05-4.30), Cornell voltage (OR 2.06, 95% CI, 1.26-3.35), and Cornell product criteria (OR 2.12, 95% CI, 1.13-3.97). Cornell voltage criterion (men, >2.8 mV; women, >2.0 mV) was associated with ischemic stroke even after adjustment for echocardiographically determined LVH (OR 1.73, 95% CI, 1.04-2.88). The combination of echo-LVH and a positive Cornell voltage criterion was associated with a 3.5-fold increase in stroke risk.

CONCLUSIONS

Our study indicates that the presence of ECG-LVH is associated with an increased risk of ischemic stroke after adjustment for other stroke risk factors. For Cornell voltage criteria, this relationship persisted even after adjustment for echocardiographic LVH. Electrocardiographic results can provide independent information for left ventricular myocardial changes and should be considered together with echocardiographic results to fully assess the risk of ischemic stroke.

Abnormal left ventricular mass and aortic distensibility in pediatric dialysis patients

There is ample evidence that the same pathophysiological processes that affect cardiovascular function in adults with end-stage renal disease (ESRD) also operate in children with ESRD. In adults undergoing hemodialysis (HD), a good correlation has been established between left ventricular mass (LVM) and aortic distensibility (AD) as markers of cardiovascular disease progression; however, this correlation has not been established in children. Therefore, in this retrospective study we investigated some aspects of cardiovascular damage (i.e., LVM, LVMI, and AD) in children with ESRD undergoing HD (n=9) or peritoneal dialysis (PD, n=9), and analyzed the relationship between AD, LVM, LVMI, pre-dialysis, post-dialysis blood pressure (BP), and demographic factors in children and adolescents with ESRD. Both LVM and AD were significantly greater in the dialysis population than in a control population derived from our institutional files (P=0.015, P=0.001). LVM and LVMI in children undergoing HD (92.9+/-83.7 g, 80.1+/-31.1 g/cm) were not statistically different from the values in children on PD (130.0+/-89.2 g, 89.6+/-35.9 g/cm), (P=0.3, P=0.5). AD in children on HD (2.2+/-0.55 cm2* dynes(-1*(10-6)) was significantly lower than in children on PD (2.7+/-0.54 cm2* dynes(-1*(10-6)), (P=0.01). The findings in this study confirm earlier studies that demonstrated that LVMI is greater in children on dialysis. This study also demonstrates that abnormal vascular stiffness, as defined by AD, is present in these children. The degree of vascular stiffness in children receiving HD is greater than in children receiving PD. However, further study is needed to address how control of BP, uremia, and other factors may affect these abnormalities in children with ESRD.

Muscle-specific RING finger 1 is a bona fide ubiquitin ligase that degrades cardiac troponin I

Muscle-specific RING finger protein 1 (MuRF1) is a sarcomere-associated protein that is restricted to cardiac and skeletal muscle. In skeletal muscle, MuRF1 is up-regulated by conditions that provoke atrophy, but its function in the heart is not known. The presence of a RING finger in MuRF1 raises the possibility that it is a component of the ubiquitin-proteasome system of protein degradation. We performed a yeast two-hybrid screen to search for interaction partners of MuRF1 in the heart that might be targets of its putative ubiquitin ligase activity. This screen identified troponin I as a MuRF1 partner protein. MuRF1 and troponin I were found to associate both in vitro and in vivo in cultured cardiomyocytes. MuRF1 reduced steady-state troponin I levels when coexpressed in COS-7 cells and increased degradation of endogenous troponin I protein in cardiomyocytes. The degradation of troponin I in cardiomyocytes was associated with the accumulation of ubiquitylated intermediates of troponin I and was proteasome-dependent. In vitro, MuRF1 functioned as a ubiquitin ligase to catalyze ubiquitylation of troponin I through a RING finger-dependent mechanism. In isolated cardiomyocytes, MuRF1 reduced indices of contractility. In cardiomyocytes, these processes may determine the balance between hypertrophic and antihypertrophic signals and the regulation of myocyte contractile responses in the setting of heart failure.

Interleukin-18 is a pro-hypertrophic cytokine that acts through a phosphatidylinositol 3-kinase-phosphoinositide-dependent kinase-1-Akt-GATA4 signaling pathway in cardiomyocytes

In patients with congestive heart failure, high serum levels of the proinflammatory cytokine interleukin (IL)-18 were reported. A positive correlation was described between serum IL-18 levels and the disease severity. IL-18 has also been shown to induce atrial natriuretic factor (ANF) gene expression in adult cardiomyocytes. Because re-expression of the fetal gene ANF is mostly associated with hypertrophy, a hallmark of heart failure, we hypothesized that IL-18 induces cardiomyocyte hypertrophy. Treatment of the cardiomyocyte cell line HL-1 with IL-18 induced hypertrophy as characterized by increases in protein synthesis, phosphorylated p70 S6 kinase, and ribosomal S6 protein levels as well as cell surface area. Furthermore, IL-18 induced ANF gene transcription in a time-dependent manner as evidenced by increased ANF secretion and ANF promoter-driven reporter gene activity. Investigation into possible signal transduction pathways mediating IL-18 effects revealed that IL-18 activates phosphoinositide 3-kinase (PI3K), an effect that was blocked by wortmannin and LY-294002. IL-18 induced Akt phosphorylation and stimulated its activity, effects that were abolished by Akt inhibitor or knockdown. IL-18 stimulated GATA4 DNA binding activity and increased transcription of a reporter gene driven by multimerized GATA4-binding DNA elements. Pharmacological inhibition or knockdown studies revealed that IL-18 induced cardiomyocyte hypertrophy and ANF gene transcription via PI3K, PDK1, Akt, and GATA4. Most importantly, IL-18 induced ANF gene transcription and hypertrophy of neonatal rat ventricular myocytes via PI3K-, Akt-, and GATA4-dependent signaling. Together these data provide the first evidence that IL-18 induces cardiomyocyte hypertrophy via PI3K-dependent signaling, defines a mechanism of IL-18-mediated ANF gene transcription, and further supports a role for IL-18 in inflammatory heart diseases including heart failure.

Swimming training increases cardiac vagal activity and induces cardiac hypertrophy in rats

The effect of swimming training (ST) on vagal and sympathetic cardiac effects was investigated in sedentary (S, N = 12) and trained (T, N = 12) male Wistar rats (200-220 g). ST consisted of 60-min swimming sessions 5 days/week for 8 weeks, with a 5% body weight load attached to the tail. The effect of the autonomic nervous system in generating training-induced resting bradycardia (RB) was examined indirectly after cardiac muscarinic and adrenergic receptor blockade. Cardiac hypertrophy was evaluated by cardiac weight and myocyte morphometry. Plasma catecholamine concentrations and citrate synthase activity in soleus muscle were also determined in both groups. Resting heart rate was significantly reduced in T rats (355 +/- 16 vs 330 +/- 20 bpm). RB was associated with a significantly increased cardiac vagal effect in T rats (103 +/- 25 vs 158 +/- 40 bpm), since the sympathetic cardiac effect and intrinsic heart rate were similar for the two groups. Likewise, no significant difference was observed for plasma catecholamine concentrations between S and T rats. In T rats, left ventricle weight (13%) and myocyte dimension (21%) were significantly increased, suggesting cardiac hypertrophy. Skeletal muscle citrate synthase activity was significantly increased by 52% in T rats, indicating endurance conditioning. These data suggest that RB induced by ST is mainly mediated parasympathetically and differs from other training modes, like running, that seems to mainly decrease intrinsic heart rate in rats. The increased cardiac vagal activity associated with ST is of clinical relevance, since both are related to increased life expectancy and prevention of cardiac events.

Regression of left ventricular hypertrophy and improvement of diastolic function in hypertensive patients treated with telmisartan

OBJECTIVES

The study was designed to test whether or not the angiotensin II receptor blocker telmisartan brings about regression of left ventricular (LV) concentric hypertrophy and whether or not these changes are associated with improved diastolic filling.

METHODS

An echocardiographic follow-up study was performed in 85 hypertensive patients (systolic blood pressure [SBP] >140 mmHg, diastolic blood pressure [DBP] >90 mmHg) and mild-to-moderate LV hypertrophy (LV mass index related to body surface area [LVMI] 117-150 g/m2 for men and 105-150 g/m2 for women) treated with telmisartan monotherapy 40-80 mg once daily for 1 year. Blood pressure, LVMI, left atrial (LA) volumes, and diastolic function were determined at baseline and after 3, 6, 9, and 12 months of treatment. Blood pressure was also monitored at all visits. Diastolic function was assessed by examination of transmitral inflow and pulmonary vein flow patterns.

RESULTS

Telmisartan reduced blood pressure; after 12 months, the mean+/-S.D. SBP and DBP were reduced from 144+/-10 to 126+/-8 mmHg (p<0.001) and from 98+/-8 to 86+/-7 mmHg (p<0.001), respectively. The LVMI was decreased from 119+/-7 to 109+/-3 g/m2 (p<0.001) after 12 months' telmisartan treatment. All patients had diastolic dysfunction at baseline. After 12 months' telmisartan treatment, a normal pattern of transmitral inflow was present in 21% of patients. The regression of LV hypertrophy observed after 12 months was associated with increased peak early diastolic velocity/peak late diastolic velocity ratio from 0.60+/-0.18 to 0.83+/-0.20 (p<0.001), shortened isovolumic relaxation time (IVRT) from 110+/-13 to 105+/-13 ms (p<0.001), and decreased deceleration time from 229+/-30 to 215+/-28 ms (p=0.002). Univariate analysis showed that shortened IVRT was related to a reduction in the LVMI and LA maximal and minimal volumes. In the multivariate analysis, the reduction in LVMI and the reduction in LA maximal and minimal volumes were independently associated with IVRT reduction.

CONCLUSIONS

Telmisartan 40-80 mg is effective in LV hypertrophy regression in hypertensive patients. The reduction in LVMI due to telmisartan monotherapy was associated with a significant improvement of diastolic filling parameters and with a significant reduction of LA volumes.

Calcium-calcineurin signaling in the regulation of cardiac hypertrophy

Cardiac hypertrophy is a leading predicator of progressive heart disease that often leads to heart failure and a loss of cardiac contractile performance associated with profound alterations in intracellular calcium handling. Recent investigation has centered on identifying the molecular signaling pathways that regulate cardiac myocyte hypertrophy, as well as the mechanisms whereby alterations in calcium handling are associated with progressive heart failure. One potential focal regulator of cardiomyocyte hypertrophy that also responds to altered calcium handling is the calmodulin-activated serine/threonine protein phosphatase calcineurin (PP2B). Once activated by increases in calcium, calcineurin mediates the hypertrophic response through its downstream transcriptional effector nuclear factor of activated T cells (NFAT), which is directly dephosphorylated by calcineurin resulting in nuclear translocation. While previous studies have convincingly demonstrated the sufficiency of calcineurin to mediate cardiac hypertrophy and progressive heart failure, its necessity remains an area of ongoing investigation. Here we weigh an increasing body of literature that suggests a causal link between calcineurin signaling and the cardiac hypertrophic response and heart failure through the use of pharmacologic inhibitors (cyclosporine A and FK506) and genetic approaches. We will also discuss the manner in which calcineurin-NFAT signaling is negatively regulated in the heart through a diverse array of kinases and inhibitory proteins. Finally, we will discuss emerging theories as to the mechanisms whereby alterations in intracellular calcium handling might stimulate calcineurin within the context of a contractile cell continually experiencing calcium flux.

Functional effects of C-type natriuretic peptide and nitric oxide are attenuated in hypertrophic myocytes from pressure-overloaded mouse hearts

Increases in the myocardial level of cGMP usually exert negative inotropic effects in the mammalian hearts. We tested the hypothesis that the negative functional effects caused by nitric oxide (NO) or C-type natriuretic peptide (CNP) through cGMP would be blunted in hypertrophied cardiac myocytes. Contractile function, guanylyl cyclase activity, cGMP-dependent protein phosphorylation, and calcium transients were assessed in ventricular myocytes from aortic stenosis-induced hypertrophic and age-matched control mice. Basal percentage shortening was similar in control and hypertrophic myocytes. S-nitroso-N-acetyl-penicillamine (SNAP, an NO donor, 10(-6) and 10(-5) M) or CNP (10(-8) and 10(-7) M) reduced percentage shortening in both groups, but their effects were blunted in hypertrophic myocytes. Maximal rates of shortening and relaxation were depressed at the basal level, and both reagents had attenuated effects in hypertrophy. Similar results were also found after treatment with guanylin and carbon monoxide, other stimulators of particulate, and soluble guanylyl cyclase, respectively. Guanylyl cyclase activity was not significantly changed in hypertrophy. Addition of Rp-8-[(4-chlorophenyl)thio]-cGMPS triethylamine (an inhibitor of cGMP-dependent protein kinase, 5 x 10(-6) M) blocked SNAP or the effect of CNP in control mice but not in hypertrophy, indicating the cGMP-dependent kinase (PKG) may not mediate the actions of cGMP induced by NO or CNP in the hypertrophic state. Calcium transients after SNAP or CNP were not significantly changed in hypertrophy. These results suggest that in hypertrophied mice, diminished effects of NO or CNP on ventricular myocyte contraction are not due to changes in guanylyl cyclase activity. The data also indicated that PKG-mediated pathways were diminished in hypertrophied myocardium, contributing to blunted effects.

Genes for left ventricular hypertrophy

Left ventricular (LV) hypertrophy is very common, particularly among hypertensives. The presence of LV hypertrophy profoundly affects morbidity and mortality from cardiovascular diseases and stroke, and is now recognized as the most important predictor of chronic heart failure. Hypertension, obesity, and diabetes are important determinants of LV hypertrophy, but they fail to identify many individuals with the condition, suggesting that other factors, likely genetic in origin, play a role. Although much research has been undertaken to understand the causes of hypertrophy and the medical treatments that can lead to its regression, much remains unknown about its genetic basis. LV hypertrophy is considered a complex genetic disease, likely representing an interaction of several genes with the environment. The heritability of LV mass, measured as a quantitative trait, falls between 0.3 and 0.7 in different populations, suggesting it has a familial component. Genes encoding proteins involved in LV structure, as well as genes encoding cell signal transduction, hormones, growth factors, calcium homeostasis, substrate metabolism, and blood pressure are likely candidates for the development of common forms of LV hypertrophy. An overview of the pathophysiology of LV hypertrophy and dysfunction is provided, in addition to evidence of the genetic basis for LV hypertrophy in humans and animal models.

Factors associated with mitral annular systolic and diastolic velocities in healthy adults

BACKGROUND

Measurements of systolic mitral annular velocity (S'), early diastolic mitral annular velocity (E'), and late diastolic mitral annular velocity (A') are used to assess left ventricular (LV) function.

OBJECTIVE

We sought to investigate the relationship between septal and lateral annular velocities and determine whether these velocities are related to body size (including body mass index [BMI]), heart rate (HR), blood pressure, or LV mass.

METHODS

A total of 60 healthy participants who were normotensive, between age 20 and 52 years, underwent standard echocardiography and measurement of septal and lateral S', E', and A'.

RESULTS

The lateral velocity exceeded the septal velocity for S', E', and A'. There was only weak to moderate correlation between the velocities at the two sites (r = 0.43-0.60). Septal S' was positively correlated with height and HR, and lateral S' was correlated with HR. Septal E' was negatively correlated with age, BMI, LV mass, and diastolic blood pressure, but lateral E' was only negatively correlated with age and BMI. Septal A' was positively correlated with age, HR, and BMI, whereas lateral A' was only positively associated with age.

CONCLUSIONS

S', E', and A' are not only of different magnitudes at the septal and lateral sites, but are not closely correlated. There are relationships between annular velocities and body size, HR, blood pressure, and LV mass that differ between the septal and lateral annulus, providing a possible explanation for the lack of close correlation in these velocities and suggesting that these variables may need to be considered when interpreting annular velocities.

NF-κB activation is required for the development of cardiac hypertrophy in vivo

In the present study, we examined whether NF-κB activation is required for cardiac hypertrophy in vivo. Cardiac hypertrophy in rats was induced by aortic banding for 1, 3, and 5 days and 1–6 wk, and age-matched sham-operated rats served as controls. In a separate group of rats, an IκB-α dominant negative mutant (IκB-αM), a superrepressor of NF-κB activation, or pyrrolidinedithiocarbamate (PDTC), an antioxidant that can inhibit NF-κB activation, was administered to aortic-banded rats for 3 wk. The heart weight-to-body weight ratio was significantly increased at 5 days after aortic banding, peaked at 4 wk, and remained elevated at 6 wk compared with age-matched sham controls. Atrial natriuretic peptide and brain natriuretic peptide mRNA expressions were significantly increased after 1 wk of aortic banding, reached a maximum between 2 and 3 wk, and remained increased at 6 wk compared with age-matched sham controls. NF-κB activity was significantly increased at 1 day, reached a peak at 3 wk, and remained elevated at 6 wk, and IKK-β activity was significantly increased at 1 day, peaked at 5 days, and then decreased but remained elevated at 6 wk after aortic banding compared with age-matched sham controls. Inhibiting NF-κB activation in vivo by cardiac transfection of IκB-αM or by PDTC treatment significantly attenuated the development of cardiac hypertrophy in vivo with a concomitant decrease in NF-κB activity. Our results suggest that NF-κB activation is required for the development of cardiac hypertrophy in vivo and that NF-κB could be an important target for inhibiting the development of cardiac hypertrophy in vivo.

Sudden death in congenital heart disease

Sudden cardiac death is a common mechanism of demise in association with congenital cardiac abnormalities. The varied mechanisms may include failure of the transitional circulation, arrhythmias, postoperative or perioperative complications in the neonate and coronary ischaemia, arrhythmias, sepsis, thrombosis, or pulmonary hypertensive crisis in the older child. Knowledge of the natural history of unoperated and operated forms of congenital heart disease and long term follow up with the detection and treatment of underlying hemodynamic abnormalities should improve outcomes. There are few patients with congenital cardiac anomalies that are cured and most require long term care.

Emerging roles of urotensin-II in cardiovascular disease

Urotensin-II (UII) is a highly potent endogenous peptide within the cardiovascular system. Through stimulation of Galphaq-coupled UT receptors, UII mediates contraction of vascular smooth muscle and endothelial-dependent vasorelaxation, and positive inotropy in human right atrium and ventricle. A pathogenic role of the UT receptor system is emerging in cardiovascular disease states, with evidence for up-regulation of the UT receptor system in patients with congestive heart failure (CHF), pulmonary hypertension, cirrhosis and portal hypertension, and chronic renal failure. In vitro and in vivo studies show that under pathophysiological conditions, UII might contribute to cardiomyocyte hypertrophy, extracellular matrix production, enhanced vasoconstriction, vascular smooth muscle cell hyperplasia, and endothelial cell hyper-permeability. Single nucleotide polymorphisms of the UII gene may also impart a genetic predisposition of patients to diabetes. Therefore, the UT receptor system is a potential therapeutic target in the treatment of cardiac, pulmonary, and renal diseases. UT receptor antagonists are currently being developed to prevent and/or reverse the effects of over-activated UT receptors by the endogenous ligand. This review describes UII peptide and converting enzymes, and UT receptors in the cardiovascular system, focusing on pathophysiological roles of UII in the heart and blood vessels.

Sex-differences in prevalence of electrocardiographic left ventricular hypertrophy in Type 2 diabetes: the Casale Monferrato Study

AIMS Although left ventricular hypertrophy (LVH) defined by either standard 12-lead ECG or echocardiography strongly predicts cardiovascular mortality, its prevalence in Type 2 diabetes is largely unknown. We have assessed prevalence of ECG-LVH and its relationship with clinical and metabolic variables in an Italian population-based cohort of subjects with Type 2 diabetes. METHODS The study-base was 965 (61.3%) subjects with Type 2 diabetes of the population-based cohort living in Casale Monferrato (Italy). LVH was defined by ECG Cornell voltage-duration product. All measurements were centralized. RESULTS ECG-LVH was diagnosed in 165/965 subjects, giving a prevalence of 17.1% (95% CI 14.7-19.5). Large sex differences were found, with higher prevalence in women (23.5%, 19.9-27.0) than in men (8.4%, 5.6-11.0), even after adjustment for age, BMI and hypertension (OR 3.83, 95% CI 2.5-5.9). At the examination, subjects with ECG-LVH were older than those without it. Similar age- and sex-adjusted values of HbA(1c), plasma lipids, fibrinogen, uric acid and creatinine were found in the two subgroups. No differences in prevalence of hypertension, CHD, increased QT duration or dispersion, micro- and macro-albuminuria were found between subjects with ECG-LVH and those without it. In logistic regression analysis, variables independently associated with ECG-LVH, after age-adjustment, were sex and diastolic blood pressure.

CONCLUSIONS

This population-based study shows: (i) a high prevalence of ECG-LVH in Type 2 diabetic subjects; (ii) 3-fold higher risk in women than in men, independently of age, BMI, and blood pressure; (iii) an independent association between ECG-LVH and diastolic blood-pressure. Screening for ECG-LVH in diabetic subjects is therefore recommended, particularly in diabetic women.

Nitric oxide and the enigma of cardiac hypertrophy

In pathological conditions associated with persistent increases in hemodynamic workload (old myocardial infarction, high blood pressure, valvular heart disease), a number of signalling pathways are activated in the heart, all of which promote hypertrophic growth of the heart, characterised at the cellular level by increases in individual cardiac myocyte size. Some of these pathways are required for a successful adaptation to cardiac injury. Other pathways are maladaptive, however, as they lead to progressive contractile dysfunction and heart failure. The free radical gas nitric oxide and natriuretic peptides, both of which are produced in the heart, have emerged as endogenous inhibitors of maladaptive hypertrophy signalling. Overall, it appears that cardiac hypertrophy is controlled by an interplay of pro- and antihypertrophic signalling networks. This delicate balance can tip towards adaptation or heart failure. In the future, patients living with cardiac disease may benefit from therapeutic strategies targeting maladaptive hypertrophy signalling pathways.

Multivariable prediction of in-hospital mortality associated with aortic and mitral valve surgery in Northern New England

BACKGROUND

Predicting risk for aortic and mitral valve surgery is important both for informed consent of patients and objective review of surgical outcomes. Development of reliable prediction rules requires large data sets with appropriate risk factors that are available before surgery.

METHODS

Data from eight Northern New England Medical Centers in the period January 1991 through December 2001 were analyzed on 8943 heart valve surgery patients aged 30 years and older. There were 5793 cases of aortic valve replacement and 3150 cases of mitral valve surgery (repair or replacement). Logistic regression was used to examine the relationship between risk factors and in-hospital mortality.

RESULTS

In the multivariable analysis, 11 variables in the aortic model (older age, lower body surface area, prior cardiac operation, elevated creatinine, prior stroke, New York Heart Association [NYHA] class IV, congestive heart failure [CHF], atrial fibrillation, acuity, year of surgery, and concomitant coronary artery bypass grafting) and 10 variables in the mitral model (female sex, older age, diabetes, coronary artery disease, prior cerebrovascular accident, elevated creatinine, NYHA class IV, CHF, acuity, and valve replacement) remained independent predictors of the outcome. The mathematical models were highly significant predictors of the outcome, in-hospital mortality, and the results are in general agreement with those of others. The area under the receiver operating characteristic curve for the aortic model was 0.75 (95% confidence interval [CI], 0.72 to 0.77), and for the mitral model, 0.79 (95% CI, 0.76 to 0.81). The goodness-of-fit statistic for the aortic model was chi(2) [8 df] = 11.88, p = 0.157, and for the mitral model it was chi(2) [8 df] = 5.45, p = 0.708.

CONCLUSIONS

We present results and methods for use in day-to-day practice to calculate patient-specific in-hospital mortality after aortic and mitral valve surgery, by the logistic equation for each model or a simple scoring system with a look-up table for mortality rate.

Mitogen-activated Protein Kinases p38 and ERK 1/2 Mediate the Wall Stress-induced Activation of GATA-4 Binding in Adult Heart

The zinc finger transcription factor GATA-4 has been implicated as a critical regulator of inducible cardiac gene expression and as a potential mediator of the hypertrophic program. However, the precise intracellular mechanisms that regulate the DNA-binding activity of GATA-4 are not fully understood. The aim of the present study was to examine the role of mitogen-activated protein kinases (p38 kinase, extracellular signal-regulated protein kinase, and c-Jun N-terminal protein kinase) in the left ventricular wall stress-induced activation of GATA-4 DNA binding in adult heart. Isolated perfused rat hearts were subjected to increased left ventricular wall stress by inflating a balloon in the ventricle. Gel mobility shift assays were used to analyze the transacting factors that interact with the GATA motifs of the B-type natriuretic peptide promoter. The left ventricular wall stress rapidly activated GATA-4 DNA binding and significantly increased the levels of phosphorylated p38 kinase, extracellular signal-regulated protein kinase, and c-Jun N-terminal protein kinase. The wall stress-induced increase in the DNA-binding activity of GATA-4 was abolished both in the presence of the p38 inhibitor SB239063 and MEK1/2 inhibitor U0126. In contrast, the inhibition of c-Jun N-terminal protein kinase by CEP11004 had no effect on the baseline or stretch-induced GATA-4 DNA binding. Moreover, GATA-4 DNA binding was up-regulated by mechanical stretch in the isolated rat atria via p38 and extracellular signal-regulated protein kinase. In conclusion, the present study demonstrates that both p38 and extracellular signal-regulated protein kinase are required for the stretch-induced GATA-4 binding in intact heart.

Adrenomedullin modulates hemodynamic and cardiac effects of angiotensin II in conscious rats

We examined whether adrenomedullin, a vasoactive peptide expressed in the heart, modulates the increase in blood pressure, changes in systolic and diastolic function, and left ventricular hypertrophy produced by long-term administration of ANG II or norepinephrine in rats. Subcutaneous administration of adrenomedullin (1.5 μg·kg−1·h−1) for 1 wk inhibited the ANG II-induced (33.3 μg·kg−1·h−1 sc) increase in mean arterial pressure by 67% ( P < 0.001) but had no effect of norepinephrine-induced (300 μg·kg−1·h−1 sc) hypertension. Adrenomedullin enhanced the ANG II-induced improvement in systolic function, resulting in a further 9% increase ( P < 0.01) in the left ventricular ejection fraction and 19% increase ( P < 0.05) in the left ventricular fractional shortening measured by echocardiography, meanwhile norepinephrine-induced changes in systolic function were remained unaffected. Adrenomedullin had no effect on ANG II- or norepinephrine-induced left ventricular hypertrophy or expression of hypertrophy-associated genes, including contractile protein and natriuretic peptide genes. The present study shows that adrenomedullin selectively suppressed the increase in blood pressure and augmented the improvement of systolic function induced by ANG II. Because adrenomedullin had no effects on ANG II- and norepinephrine-induced left ventricular hypertrophy, circulating adrenomedullin appears to act mainly as a regulator of vascular tone and cardiac function.

Activation of AMP-activated protein kinase inhibits protein synthesis associated with hypertrophy in the cardiac myocyte

A necessary mediator of cardiac myocyte enlargement is protein synthesis, which is controlled at the levels of both translation initiation and elongation. Eukaryotic elongation factor-2 (eEF2) mediates the translocation step of peptide-chain elongation and is inhibited through phosphorylation by eEF2 kinase. In addition, p70S6 kinase can regulate protein synthesis by phosphorylating eEF2 kinase or via phosphorylation of ribosomal protein S6. We have recently shown that eEF2 kinase is also controlled by phosphorylation by AMP-activated protein kinase (AMPK), a key regulator of cellular energy homeostasis. Moreover, the mammalian target of rapamycin has also been shown to be inhibited, indirectly, by AMPK, thus leading to the inhibition of p70S6 kinase. Although AMPK activation has been shown to modulate protein synthesis, it is unknown whether AMPK could also be a regulator of cardiac hypertrophic growth. Therefore, we investigated the role of AMPK activation in regulating protein synthesis during both phenylephrine- and Akt-induced cardiac hypertrophy. Metformin and 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside were used to activate AMPK in neonatal rat cardiac myocytes. Activation of AMPK significantly decreased protein synthesis induced by phenylephrine treatment or by expression of constitutively active Akt. Activation of AMPK also resulted in decreased p70S6 kinase phosphorylation and increased phosphorylation of eEF2, suggesting that inhibition of protein synthesis involves the eEF2 kinase/eEF2 axis and/or the p70S6 kinase pathway. Together, our data suggest that the inhibition of protein synthesis by pharmacological activation of AMPK may be a key regulatory mechanism by which hypertrophic growth can be controlled.

Activation of IP prostanoid receptors prevents cardiomyocyte hypertrophy via cAMP-dependent signaling

The antihypertrophic action of angiotensin-converting enzyme inhibitors in the heart results partly from local potentiation of bradykinin. We have demonstrated that the antihypertrophic action of bradykinin is mediated by the release of nitric oxide from endothelium and elevation of cardiomyocyte cGMP. Whether other paracrine factors derived from the coronary endothelium, such as prostacyclin (PGI2), may act to prevent hypertrophy has not been explored. In the vasculature, activation by PGI2 of IP and EP1 prostanoid receptors elicits vasodilatation (via cAMP-dependent signaling) and vasoconstriction, respectively. The present objective was to determine whether IP prostanoid receptor activation has antihypertrophic actions in adult rat cardiomyocytes (ARCM). The selective IP agonist cicaprost (1 microM) virtually abolished the increase in [3H]phenylalanine incorporation (a marker of hypertrophy) induced either by endothelin-1 (ET-1; 60 nM, n = 10, P < 0.005) or by angiotensin II (1 microM, n = 6, P < 0.005). Cicaprost also inhibited ET-1 induction of c-fos mRNA expression, an additional marker of hypertrophy in ARCM (n = 5, P < 0.005). In the absence of hypertrophic stimuli, cicaprost alone did not significantly influence either marker. The antihypertrophic actions of cicaprost were mimicked by the dual IP/EP1 agonist iloprost (1 microM) in the presence of the EP1 antagonist AH-6809 (3 microM). Furthermore, cicaprost modestly but significantly increased cardiomyocyte cAMP content by 13 +/- 6% (P < 0.05, n = 4), and the antihypertrophic effect of cicaprost was lost in the presence of the cAMP-dependent protein kinase inhibitor H-89 (1 microM, n = 5, P < 0.05). However, ET-1 also induced increases in the activity of the intracellular growth signals ERK1 (by 3-fold) and ERK2 (by 5-fold) in ARCM, and these were not inhibited by cicaprost (P < 0.01, n = 5). Activation of IP receptors thus represents a novel approach to prevention of hypertrophy, and this effect is linked to cAMP-dependent signaling.

Left ventricular mass increases with deteriorating glucose tolerance, especially in women: independence of increased arterial stiffness or decreased flow-mediated dilation: the Hoorn study

OBJECTIVE

Type 2 diabetes and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease (CVD) risk. Increased left ventricular mass (LVM) is thought to increase CVD risk through several unfavorable cardiac changes. Type 2 diabetes and IGM are associated with increased LVM, but the underlying mechanism is unclear. We investigated the association between glucose tolerance status (GTS) and LVM and explored whether any such association could be mediated through increased arterial stiffness, impaired endothelial function, or the presence of atherosclerosis.

RESEARCH DESIGN AND METHODS

We used ultrasound to measure LVM, carotid and femoral stiffness, carotid-femoral transit time, and flow-mediated vasodilation (FMD) and tonometry to estimate compliance and augmentation index. The study population (n = 780) consisted of 287 individuals with normal glucose metabolism (NGM), 179 with IGM, and 314 with type 2 diabetes, and the mean age was 68.4 years.

RESULTS

In women, after adjusting for age, height, BMI, and mean arterial pressure, LVM increased significantly with deteriorating GTS (LVM 157 g in NGM, 155 g in IGM, and 169 g in type 2 diabetes; P for trend <0.018). Additional adjustment for arterial stiffness, FMD, or the presence of atherosclerosis did not materially alter the results, even though these variables were significantly associated with both GTS and LVM. Indexes of hyperglycemia/-insulinemia or insulin resistance explained at most 7% of the association between GTS and LVM. In men, no statistically significant associations were observed.

CONCLUSIONS

Our data expand the conceptual view of the pathogenesis of GTS-related changes in LVM because we show that the increase in LVM in women is independent of increased arterial stiffness, impaired FMD, or the presence of atherosclerosis. In addition, we show that this increase in LVM is only minimally explained by indexes of hyperglycemia/-insulinemia or insulin resistance. Our data may, in part, explain the increased CVD risk seen in women with deteriorating GTS.

Cardiac remodeling in systemic hypertension

Experimental and clinical studies provide evidence that hypertension is causally related to adverse cardiac structural changes, such as LA enlargement, LV hypertrophy and myocardial fibrosis, and functional changes inclusive of LV systolic and diastolic dysfunction. These changes are induced by both hemodynamic and nonhemodynamic factors. There is accumulating evidence from several small and large clinical trials that various classes of antihypertensive therapy prevent and regress LVH and myocardial fibrosis. Prevention and reversal of LVH are associated with an improvement in cardiac function and with a decline in risk of adverse cardiovascular outcomes. Prevention of LVH should be a priority in subjects with hypertension. In patients with hypertensive heart disease, the components of therapy must comprise optimization of BP and regression of LVH. Future targets of therapy in hypertensive heart disease may include regression of myocardial fibrosis, normalization of LA size, and improvement in LV diastolic function.

Duration-controlled swimming exercise training induces cardiac hypertrophy in mice

Exercise training associated with robust conditioning can be useful for the study of molecular mechanisms underlying exercise-induced cardiac hypertrophy. A swimming apparatus is described to control training regimens in terms of duration, load, and frequency of exercise. Mice were submitted to 60- vs 90-min session/day, once vs twice a day, with 2 or 4% of the weight of the mouse or no workload attached to the tail, for 4 vs 6 weeks of exercise training. Blood pressure was unchanged in all groups while resting heart rate decreased in the trained groups (8-18%). Skeletal muscle citrate synthase activity, measured spectrophotometrically, increased (45-58%) only as a result of duration and frequency-controlled exercise training, indicating that endurance conditioning was obtained. In groups which received duration and endurance conditioning, cardiac weight (14-25%) and myocyte dimension (13-20%) increased. The best conditioning protocol to promote physiological hypertrophy, our primary goal in the present study, was 90 min, twice a day, 5 days a week for 4 weeks with no overload attached to the body. Thus, duration- and frequency-controlled exercise training in mice induces a significant conditioning response qualitatively similar to that observed in humans.

c-Jun N-terminal kinases (JNK) antagonize cardiac growth through cross-talk with calcineurin-NFAT signaling

The c-Jun N-terminal kinase (JNK) branch of the mitogen-activated protein kinase (MAPK) signaling pathway regulates cellular differentiation, stress responsiveness and apoptosis in multicellular eukaryotic organisms. Here we investigated the functional importance of JNK signaling in regulating differentiated cellular growth in the post-mitotic myocardium. JNK1/2 gene-targeted mice and transgenic mice expressing dominant negative JNK1/2 were determined to have enhanced myocardial growth following stress stimulation or with normal aging. A mechanism underlying this effect was suggested by the observation that JNK directly regulated nuclear factor of activated T-cell (NFAT) activation in culture and in transgenic mice containing an NFAT-dependent luciferase reporter. Moreover, calcineurin Abeta gene targeting abrogated the pro-growth effects associated with JNK inhibition in the heart, while expression of an MKK7-JNK1 fusion protein in the heart partially reduced calcineurin-mediated cardiac hypertrophy. Collectively, these results indicate that JNK signaling antagonizes the differentiated growth response of the myocardium through direct cross-talk with the calcineurin-NFAT pathway. These results also suggest that myocardial JNK activation is primarily dedicated to modulating calcineurin-NFAT signaling in the regulation of differentiated heart growth.

Left ventricular hypertrophy is a common echocardiographic abnormality in severe obstructive sleep apnea and reverses with nasal continuous positive airway pressure

STUDY OBJECTIVES

To determine cardiac structural abnormalities by echocardiography in subjects with severe obstructive sleep apnea (OSA), and to determine the long-term effects of nasal continuous positive airway pressure (CPAP) on such abnormalities.

DESIGN

Polysomnography was conducted on oximetry-screened patients who showed a desaturation index > 40/h and > or = 20% cumulative time spent below 90%. From these, 25 patients with severe OSA but without daytime hypoxemia underwent echocardiography prior to, then 1 month and 6 months following initiation of CPAP treatment.

SETTING

Outpatient sleep disorders center.

RESULTS

Of the 25 patients, 13 patients (52%) had hypertension by history or on physical examination. Baseline echocardiograms showed that severe OSA was associated with numerous cardiovascular abnormalities, including left ventricular hypertrophy (LVH) [88%], left atrial enlargement (LAE) [64%], right atrial enlargement (RAE) [48%], and right ventricular hypertrophy (16%). In all patients (intent to treat) as well as those patients compliant with CPAP therapy (84% > 3 h nightly), there was a significant reduction in LVH after 6 months of CPAP therapy as measured by interventricular septal distance (baseline diastolic mean, 13.0 mm; 6-month mean after CPAP, 12.3 mm; p < 0.02). RAE and LAE were unchanged after CPAP therapy.

CONCLUSIONS

LVH was present in high frequency in subjects with severe OSA and regressed after 6 months of nasal CPAP therapy.

GATA-4 is a nuclear mediator of mechanical stretch-activated hypertrophic program

In overloaded heart the cardiomyocytes adapt to increased mechanical and neurohumoral stress by activation of hypertrophic program, resulting in morphological changes of individual cells and specific changes in gene expression. Accumulating evidence suggests an important role for the zinc finger transcription factor GATA-4 in hypertrophic agonist-induced cardiac hypertrophy. However, its role in stretch-induced cardiomyocyte hypertrophy is not known. We employed an in vitro mechanical stretch model of cultured cardiomyocytes and used rat B-type natriuretic peptide promoter as stretch-sensitive reporter gene. Stretch transiently increased GATA-4 DNA binding activity and transcript levels, which was followed by increases in the expression of B-type natriuretic peptide as well as atrial natriuretic peptide and skeletal alpha-actin genes. The stretch inducibility mapped primarily to the proximal 520 bp of the B-type natriuretic peptide promoter. Mutational studies showed that the tandem GATA consensus sites of the proximal promoter in combination with an Nkx-2.5 binding element are critical for stretch-activated B-type natriuretic peptide transcription. Inhibition of GATA-4 protein production by adenovirus-mediated transfer of GATA-4 antisense cDNA blocked stretch-induced increases in B-type natriuretic peptide transcript levels and the sarcomere reorganization. The proportion of myocytes with assembled sarcomeres in control adenovirus-infected cultures increased from 14 to 59% in response to stretch, whereas the values for GATA-4 antisense-treated cells were 6 and 13%, respectively. These results show that activation of GATA-4, in cooperation with a factor binding on Nkx-2.5 binding element, is essential for mechanical stretch-induced cardiomyocyte hypertrophy.

Left ventricular hypertrophy: virtuous intentions, malign consequences

Left ventricular hypertrophy (LVH) is currently the focus of intense cardiovascular research, with the resultant rapid evolution of novel concepts relating to its exceedingly complex pathophysiology. In addition to the alterations in signal transduction and disturbances in Ca(2+) homeostasis, there are structural changes in myofilaments, disorganization of the cytoskeletal framework and increased collagen synthesis. LVH is associated with progressive left ventricular remodeling that culminates to heart failure. The modern treatment of left ventricular hypertrophy is now largely based on the hypothesis that neuroendocrine activation is important in the progression of the disease and inhibition of neurohormones is likely to have long-term benefit with regard to morbidity and mortality. Drugs specifically designed to unload the left ventricle, such as diuretics and vasodilators, appears to be less effective in reducing LV mass and improving prognosis. Thus, the evolution of treatment for LVH itself has provided much enlightenment for our understanding of the fundamental biology of the disorder.

Targeted inhibition of p38 MAPK promotes hypertrophic cardiomyopathy through upregulation of calcineurin-NFAT signaling

The MAPKs are important transducers of growth and stress stimuli in virtually all eukaryotic cell types. In the mammalian heart, MAPK signaling pathways have been hypothesized to regulate myocyte growth in response to developmental signals or physiologic and pathologic stimuli. Here we generated cardiac-specific transgenic mice expressing dominant-negative mutants of p38alpha, MKK3, or MKK6. Remarkably, attenuation of cardiac p38 activity produced a progressive growth response and myopathy in the heart that correlated with the degree of enzymatic inhibition. Moreover, dominant-negative p38alpha, MKK3, and MKK6 transgenic mice each showed enhanced cardiac hypertrophy following aortic banding, Ang II infusion, isoproterenol infusion, or phenylephrine infusion for 14 days. A mechanism underlying this enhanced-growth profile was suggested by the observation that dominant-negative p38alpha directly augmented nuclear factor of activated T cells (NFAT) transcriptional activity and its nuclear translocation. In vivo, NFAT-dependent luciferase reporter transgenic mice showed enhanced activation in the presence of the dominant-negative p38alpha transgene before and after the onset of cardiac hypertrophy. More significantly, genetic disruption of the calcineurin Abeta gene rescued hypertrophic cardiomyopathy and depressed functional capacity observed in p38-inhibited mice. Collectively, these observations indicate that reduced p38 signaling in the heart promotes myocyte growth through a mechanism involving enhanced calcineurin-NFAT signaling.

Exercise blood pressure response is related to left ventricular mass

An exaggerated SBP response to exercise has been associated with increased left ventricular (LV) mass in some but not all studies. A total of 43 women and 34 men, aged 55-75 years, without evidence of cardiovascular disease, with a mean resting BP of 142+/-9/77+/-8 mmHg had their BP measured at rest and during maximal treadmill exercise. LV mass was measured using magnetic resonance imaging. LV mass was adjusted for lean body mass, which was assessed by dual energy X-ray absorptiometry. LV mass was within the normal range for the majority of the subjects. Among the resting and exercise BP indices, maximal SBP was the strongest correlate of LV mass (r=0.41, P<0.05). In multivariate analysis, maximal SBP was independently associated with LV mass after adjustment for lean body mass and gender, explaining 3% of the variance (P<0.05). Maximal exercise SBP is a modest but still independent predictor of LV mass in older persons with normal LV mass. These results raise the possibility that the SBP response to maximal exercise is an early marker of LV hypertrophy.

Analysis of cardiopulmonary transit times at contrast material-enhanced MR imaging in patients with heart disease

PURPOSE

To build a database of arm-to-aorta circulation times for contrast enhancement and to determine if measured transit times can help in discrimination between patients with and patients without heart disease.

MATERIALS AND METHODS

Findings at test-bolus examinations performed before acquisition of contrast material-enhanced magnetic resonance (MR) angiographic images of the head and neck were retrospectively reviewed. The times from test-bolus injection to first and peak enhancement in regions of interest were recorded in 77 patients with coronary artery disease, left ventricular hypertrophy, and/or impaired left ventricular function and 33 control subjects. Transit times in patients and control subjects were compared with Student t test. Linear regression was performed to measure the correlation coefficient.

RESULTS

Transit times in patients with heart disease, including those with a normal ejection fraction, were significantly prolonged compared with those in control subjects (P <.05). Mean time to peak enhancement in the carotid artery bifurcation was 16.6 seconds +/- 1.9 (SD) and 20.8 seconds +/- 3.9 in control subjects and patients, respectively. Threshold value of 18 seconds for time to peak signal intensity in the carotid artery bifurcation provided highest combination of sensitivity and specificity. All (11 of 11) patients with an ejection fraction less than 40% and only three (9%) of 33 control subjects had circulation times greater than this threshold. No significant correlation was found between transit times and age, sex, weight, and height.

CONCLUSION

Transit times measured with MR imaging may help in discrimination between patients with and patients without heart disease, independently of other cardiac functional parameters.

Pulse pressure responses to psychological tasks improve the prediction of left ventricular mass: 10 years of follow-up

OBJECTIVES

To examine the role of casual blood pressure measurements and blood pressure responses to psychological tasks in the prediction of future left ventricular mass index (LVMI), and to determine the importance of different components of blood pressure, and the predictive value of an individual's personal characteristics and antihypertensive medication on future LVMI.

METHODS

At baseline, blood pressure was recorded by casual measurements; during tests it was recorded by intra-arterial monitoring. The participants were healthy, untreated 35-45-year old men. Echocardiography data both at baseline and after 10 years of follow-up were available from 65 individuals, of whom 49 (75%) were not taking antihypertensive medication at follow-up. Those not taking antihypertensive medication were included in the prediction of LVMI (g/m2).

RESULTS

Baseline LVMI correlated significantly with future LVMI only among the 49 unmedicated individuals (r = 0.52, P < 0.0001). The predictive value of baseline LVMI on future LVMI among them (adjusted coefficient of determination = 0.26) was not improved by the inclusion of casual blood pressure. In contrast, blood pressure responses to the psychological tasks improved the prediction of future LVMI by 4-13%. Pulse pressure was the blood pressure variable that entered the final prediction models; the correlations with future LVMI were best for pulse pressure response to habituation task (r = 0.43, P < 0.05) and to relaxation (r = 0.37, P < 0.05).

CONCLUSIONS

To our knowledge, this is the longest prospective follow-up to show that blood pressure responses to psychological tasks improve the prediction of LVMI compared with casual blood pressure measurements. The pulse pressure, which reflects the properties of the arterial wall, is the most significant blood pressure variable in predicting future LVMI.

Endothelin-1-specific activation of B-type natriuretic peptide gene via p38 mitogen-activated protein kinase and nuclear ETS factors

Terminally differentiated cardiac myocytes adapt to mechanical and neurohumoral stress via morphological changes of individual cells accompanied by reactivation of fetal pattern of gene expression. Endothelin-1, a powerful paracrine mediator of myocyte growth, induces similar changes in cultured cardiac myocytes as those seen in hypertrophied heart in vivo. By using rat B-type natriuretic peptide promoter, we identified a novel ETS binding sequence, on which nuclear protein binding is activated in endothelin-1-treated cultured cardiac myocytes. This sequence binds ETS-like gene-1 transcription factor and mediates endothelin-1-specific activation of transcription, but not responses to increased calcium signaling via l-type calcium channels, angiotensin II treatment, or mechanical stretch of myocytes. Interestingly, endothelin-1 activated signaling converges via p38 mitogen-activated protein kinase-dependent mechanism on ETS binding site, whereas this element inhibits extracellular signal-regulated kinase activated transcription. In conclusion, given the fundamental role of the interaction of mitogen-activated protein kinases and ETS factors in regulation of eukaryotic cell differentiation, growth, and oncogenesis, these results provide the unique evidence of a endothelin-1- and mitogen-activated protein kinase-regulated ETS factor pathway for cardiac myocytes.

Screening for treatable left ventricular abnormalities in diabetic patients

Cardiovascular disease is the leading cause of death in patients with diabetes mellitus. Attempts to improve this statistic tend to focus primarily on the prevention of coronary artery disease. However, coronary artery disease is not the sole cause of cardiac death in diabetic patients; left ventricular dysfunction (LVD) and left ventricular hypertrophy (LVH) are also implicated and, unlike coronary artery disease, are ideal targets for screening. The treatment of left ventricular abnormalities, even when these are asymptomatic, is associated with prognostic benefit. Prescreening diabetic patients with plasma B-type natriuretic peptide (BNP) may permit identification of those who are likely to have left ventricular abnormalities, so that they may be put forward for echocardiography and receive targeted therapy.

Relation of coronary artery calcium to left ventricular mass and geometry in patients with essential hypertension

BACKGROUND

There is a close relationship between left ventricular hypertrophy and cardiovascular diseases that are observed in hypertension. In this study, the amount of coronary artery calcium, which is an indicator of atherosclerosis, has been measured and its relationship with left ventricular hypertrophy and geometry and other traditional risk factors has been investigated.

DESIGN

A total of 249 (104 females, 145 males) hypertensive asymptomatic patients, without diabetes with an average age of 55.09 +/- 11.32 years were included in the study. Left ventricular mass of the patients was measured with M-mode echocardiography and coronary artery calcium with electron beam tomography. The average age of the patients who had calcium in their coronary arteries (CAC+) was 59.99 +/- 9.85 years, and the average age of the ones without calcium (CAC-) was 49.29 +/- 10.19 years.

RESULTS

Mean left ventricular mass index (LVMI) was measured as 130.18 +/- 43.24 g/m2 in CAC+ patients and as 108.47 +/- 29.09 g/m2 in CAC- patients. These two groups did not differ in terms of the parameters such as total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride and uric acid levels, the presence of early coronary disease in the family and smoking. Patients who had calcium in their coronary arteries (CAC+) were more obese (P < 0.004). In the logistic regression analysis, we demonstrated that body mass index and age were the factors affecting the presence and amount of calcification seen in coronary arteries in left ventricular hypertrophy. In the analysis performed by taking left ventricular hypertrophy into consideration, mean calcium scores of the patients with normal remodeling, concentric remodeling, eccentric hypertrophy and concentric hypertrophy were 50.9 +/- 187.4, 68.6 +/- 159.3, 92.2 +/- 160.2 and 315.4 +/- 760.6, respectively. In the patients with concentric left ventricular hypertrophy (LVH), the mean calcium scores of the coronary arteries and the rate of being CAC+ were significantly high, although these patients were also older. After linear regression, the relationship between concentric LVH and coronary artery calcium (CAC) was still significant.

CONCLUSION

In conclusion, left ventricular hypertrophy that is observed in hypertension is an important risk factor for sub-clinical atherosclerosis. Concentric left ventricular hypertrophy is a more important risk factor than other geometric patterns.

Determinants of left atrial size in patients with newly diagnosed untreated hypertension

The present study determined the relationships between ambulatory blood pressure, left ventricular mass, body mass index, and other clinical and demographic variables to left atrial size in previously untreated hypertensive and normotensive subjects. Left atrial size was measured uni-dimensionally using M-mode echocardiography in 58 newly diagnosed never-treated hypertensive patients (office blood pressure 149/96 +/- 15/7 mmHg) and 28 normotensive control subjects (office blood pressure, 122/78 +/- 8/8 mmHg). Left ventricular mass, septal and posterior wall thickness were significantly increased in hypertensive compared to normotensive subjects (230 +/- 63 g versus 181 +/- 45 g, 1.1 +/- 0.2 cm versus 0.94 +/- 0.2 cm, and 1.04 +/- 0.2 cm versus 0.92 +/- 0.2 cm respectively; all p < 0.001). Left ventricular internal diameter (4.9 +/- 0.6 versus 4.8 +/- 0.4 cm, = 0.54) and left atrial size (3.74 +/- 0.48 versus 3.70 +/- 0.34 cm, p = 0.86) were not different between the two groups respectively. Body mass index, weight, left ventricular mass, wall thickness, and 24-h pulse pressure were significant correlates of left atrial size in the entire group and in the hypertensive subgroup. In the normotensive subgroup, body weight, body mass index, 24-h systolic and pulse pressure, and left ventricular mass were significant correlates. Multiple regression analyses in the entire group and the hypertensive subgroup alone showed that body mass index and left ventricular mass were the two best predictors of left atrial dimension. These data demonstrate that body mass index and left ventricular mass were the main correlates of left atrial size in patients with previously untreated stage I-II hypertension.

Sex dependence and temporal dependence of the left ventricular genomic response to pressure overload

To characterize responses of the left ventricle (LV) to pressure overload at the genomic level, we performed high-density microarray analysis on individual mouse LVs. Male and female mice underwent transverse aortic constriction. At 1 day and 30 wk, the LV free wall was harvested and RNA isolated from 27 individual ventricles was analyzed on Mu74Av2 GeneChips, which contain approximately 12,483 distinct genes. Interestingly, a greater number of genes was regulated in response to acute overload than in response to chronic overload. Hierarchical cluster analysis revealed the presence of several distinct expression profiles. Of these clusters, the majority contained genes that were regulated either in response to acute overload or both acute and chronic overload. In addition, clusters revealing sex-specific responses to overload were detected. In summary, the acute and chronic genomic responses to pressure overload are distinct. Moreover, sex modifies these responses. Furthermore, these studies have uncovered several novel and potentially important genes that are regulated in response to overload and may open unrecognized avenues for further functional analysis.

Value of rilmenidine therapy and its combination with perindopril on blood pressure and left ventricular hypertrophy in patients with essential hypertension (VERITAS)

OBJECTIVES

The primary objective was to assess the effects of rilmenidine monotherapy and in combination with perindopril on blood pressure (BP) in patients assessed with grade 1 or 2 essential hypertension. The study also examined the effects of 2-year rilmenidine monotherapy on left ventricular hypertrophy (LVH) and on diastolic function of the left ventricle, along with the effects of rilmenidine on left ventricular mass index in hypertensive patients with no LVH, and the relationship between BP reduction and any change in LVH.

RESEARCH DESIGN AND METHODS

Mild-to-moderate hypertensive patients (n = 500) were enrolled in a multicentre 2-year open study and treated with rilmenidine (1-2 mg per day) monotherapy or rilmenidine plus perindopril (2, 4 or 8 mg per day) if control of hypertension was not achieved with rilmenidine monotherapy within 12 weeks. Blood pressure was recorded at regular intervals by the investigators and LVH measured by centralised single-blind echocardiographic reading.

RESULTS

Rilmenidine monotherapy (average dose 1.42 mg) produced a significant decrease in BP from the baseline of 163 +/- 10/100 +/- 5 mmHg to 134 +/- 10/86 +/- 7 mmHg at 1 year and to 136 +/- 10/84 +/- 7 mmHg at 2 years (p < 0.001 for both). In 188 patients with LVH, the left ventricular mass index was significantly reduced from 161.4 +/- 30.5 to 131.3 +/- 26.5 at 1 year and to 134.1 +/- 26.0 g/m(2) at 2 years (p < 0.001 for both). Addition of perindopril to those patients whose BP was not normalised by rilmenidine monotherapy after 12 weeks further decreased BP significantly from 150 +/- 13/93 +/- 8 mmHg to 142 +/- 14/89 +/- 7 mmHg at the end of the 2nd year.

CONCLUSIONS

Long-term rilmenidine monotherapy was shown to be efficient in controlling BP and in reducing LVH. The addition of perindopril to rilmenidine monotherapy proved to be effective and well tolerated in those patients who did not respond to rilmenidine alone.

Requirement of nuclear factor of activated T-cells in calcineurin-mediated cardiomyocyte hypertrophy

The calcium-activated phosphatase calcineurin has been implicated as a critical intracellular signal transducer of cardiomyocyte hypertrophy. Although previous data suggested the nuclear factor of activated T-cells (NFAT) as its sole transcriptional effector, the absolute requirement of NFAT as a mediator of calcineurin signaling has not been examined in the heart. We therefore investigated the expression and activation profile of NFAT genes in the heart. Four members (NFATc1-c4) are expressed in cardiomyocytes, elicit nuclear translocation upon calcineurin activation, and are able to drive transactivation of cardiac promoter luciferase constructs. To define the necessary function of NFAT factors as hypertrophic transducers, a dominant negative NFAT construct was created, encompassing part of the N-terminal region of NFATc4 containing a conserved calcineurin-binding motif. Cotransfection of this construct dose-dependently abrogated promoter activation, irrespective of the NFAT isoform used, whereas a control construct with the calcineurin-binding motif mutated displayed no such effects. Adenoviral gene transfer of dominant negative NFAT rendered cardiomyocytes resistant toward all aspects of calcineurin or agonist-induced cardiomyocyte hypertrophy, whereas adenoviral gene transfer of the control construct had no discernable effect on these parameters. These results indicate that multiple NFAT isoforms are expressed in cardiomyocytes where they function as necessary transducers of calcineurin in facilitating cardiomyocyte hypertrophy.