Long-term plasma catecholamines in patients with hypertension and left ventricular hypertrophy treated with losartan or atenolol: ICARUS, a LIFE substudy

Correlation between Serum Calcineurin Activity and Left Ventricular Hypertrophy in Hypertensive Patients and Its Clinical Significance

OBJECTIVE

The aim of this study is to investigate the correlation between calcineurin (CaN) and hypertension with left ventricular hypertrophy (HLVH) and to evaluate its potential clinical significance.

DESIGN

The study involved 160 patients diagnosed with hypertension and 42 controls. Based on the exclusion criteria, 42 were not eligible for this study. The remaining 118 hypertensive patients were categorized into 2 subgroups based on left ventricular mass index and relative ventricular wall thickness: a normal model subgroup with hypertension (HNM) and an HLVH subgroup. Serum CaN levels were determined by enzyme-linked immunosorbent assay, while serum CaN activity was determined by malachite green colorimetric assay.

RESULTS

Among the HNM and HLVH subgroups, a positive correlation was demonstrated between serum CaN activity, but not serum CaN level, and HLVH. Moreover, the HLVH subgroup displayed a remarkable increase in the levels of brain natriuretic peptide, cystatin C, urinary albumin/creatinine ratio, and left atrium diameter compared to the HNM subgroup and controls.

CONCLUSION

There was a positive correlation between serum CaN activity and LVH in hypertensive patients. Activated CaN could play an important role in the pathophysiologic mechanism of HLVH. Serum CaN activity could be a clinically useful diagnostic and prognostic biomarker for LVH.

Postural orthostatic tachycardia syndrome: diagnosis and treatment

BACKGROUND

Postural orthostatic tachycardia syndrome (POTS) is an autonomic disorder characterized by an exaggerated increase in heart rate that occurs during standing, without orthostatic hypotension. Women are most frequently affected, and may present with palpitations, chest discomfort, shortness of breath, weakness, exercise intolerance, lightheadedness, presyncope, and syncope.

METHODS

We present three cases of POTS in otherwise healthy women, and discuss the clinical management of different types of this orthostatic intolerance.

RESULTS AND CONCLUSION

The diagnosis was established with a tilt-table test in 1 patient who became symptom-free with β-blockade and nonpharmacologic treatment, including fluid therapy, liberal sodium intake, support hose, and a reconditioning exercise program. The other 2 were diagnosed through a standing test, serum norepinephrine levels, and red-cell volumes. One patient had neuropathic POTS and partially responded to b-blockade and nonpharmacotherapy. The other patient had hyperadrenergic POTS and responded well to nonpharmacotherapy, a dualacting b-blocker, and a vasoconstrictor agent. Postural orthostatic tachycardia syndrome is not an uncommon clinical entity and making a correct diagnosis is crucial in providing appropriate treatment to restore patients' functional capability and quality of life.

Efficacy of exercise, losartan, enalapril, atenolol and rilmenidine in subjects with blood pressure hyperreactivity at treadmill stress test and left ventricular hypertrophy

High levels of activity of the renin-angiotensin system (RAS) and sympathetic nervous system (SNS) are related to left ventricular hypertrophy (LVH). A percentage of subjects with hyperactivity to treadmill stress test show LVH to echocardiogram. This paper aims at evaluating neurohumoral influence over these subjects by comparing drugs that block both the RAS and the SNS. In a 1-year open protocol, 195 normotensive subjects, with hyperactivity to treadmill stress test and LVH, were randomly assigned to supervised physical exercise, rilmenidine 1 mg day(-1), atenolol 50 mg day(-1), enalapril 10 mg day(-1) or losartan 50 mg day(-1). Changes in left ventricular mass index (LVMI), measured by means of echocardiogram, were the primary end point. Changes in systolic blood pressure (SBP) at rest and peak effort were also evaluated. Enalapril significantly brought LVMI down in relation to the basal value (28.2%; n=36) similarly to losartan (26.9%; n=42); P>0.05. However, both were more efficient than physical exercise (2.9%; n=39), rilmenidine (5.1%; n=38) and atenolol (7.2%; n=40); P<0.001. There was no significant difference in SBP reduction at rest and peak effort in groups assigned to atenolol, enalapril and losartan; P>0.05. In such groups, reduction was greater than in groups assigned to physical exercise and rimenidine; P<0.001. In conclusion, drugs that block RAS were more efficient in reducing LVH than physical exercise and drugs that block SNS, and such reduction took place regardless of SBP level reduction at rest and peak effort.

Simulated microgravity produces attenuated baroreflex-mediated pressor, chronotropic, and inotropic responses in mice

Whether myocardial contractile impairment contributes to orthostatic intolerance (OI) is controversial. Accordingly, we used transient bilateral carotid occlusion (TBCO) to compare the in vivo pressor, chronotropic, and inotropic responses (parts 1 and 2) to open-loop selective carotid baroreceptor unloading in anesthetized mice. In part 3, in vitro myocyte responses to isoproterenol in mice exposed to hindlimb unweighting (HLU) for approximately 2 wk were determined. Heart rate (HR) and mean arterial pressure (MAP) responses to TBCO were measured. In control mice, TBCO increased HR (15 +/- 2 beats/min, P < 0.05) and MAP (17 +/- 2 mmHg, P < 0.05). These responses were markedly potentiated in denervated control (DC) mice, in which the aortic depressor nerve and sympathetic trunk were sectioned before measurement. Baroreflex responses to TBCO were eliminated by blockade with hexamethonium bromide (10 microg/kg). In HLU (denervated) mice, HR and MAP responses were reduced approximately 70% compared with DC mice. In part 2, myocardial contractile responses to TBCO were measured with a left ventricular micromanometer-conductance catheter. TBCO in DC mice increased the slope of the end-systolic pressure-volume relation (end-systolic elastance) by 86 +/- 13%. This inotropic response was attenuated (14 +/- 10%, P < 0.005) after HLU. In part 3, contractile responses to isoproterenol were impaired in myocytes isolated from HLU mice. In conclusion, selective carotid baroreceptor unloading stimulates HR, blood pressure, and myocardial contractility, and HLU attenuates each response. These findings have important implications for the management of OI in astronauts, the elderly, and individuals subjected to prolonged bed rest.