Reversal of cardiac and large artery structural abnormalities induced by long-term antihypertensive treatment with trandolapril

Aortic remodelling following the treatment and regression of hypertensive left ventricular hypertrophy: a cardiovascular magnetic resonance study

BACKGROUND

Increased arterial stiffness independently predicts adverse prognosis. While different antihypertensive strategies produce different magnitudes of left ventricular hypertrophy (LVH) regression, there are no comparative data on how these strategies affect arterial stiffness. The aim was to determine the longitudinal change in aortic stiffness following the treatment of essential hypertension with two mechanistically different antihypertensive treatment strategies.

METHODS AND RESULTS

Forty-two patients with essential hypertension and CMR confirmed with LVH were randomly assigned to antihypertensive regimes for 6 months. Treatment strategies were designed either to inhibit the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) (valsartan and moxonidine, group VM) or to have neutral effect on these systems (bendroflumethiazide and amlodipine, group BA). Both treatment groups underwent identical baseline and a 6-month follow-up CMR and were compared with a healthy age-matched control group. Baseline aortic distensibility (AD) was lower in both hypertensive groups compared with controls (2.8 × 10(-3 )mmHg(-1) in group VM (p = 0.001) and 3.3 × 10(-3 )mmHg(-1) group BA (p = 0.039) compared with 4.5 × 10(-3 )mmHg(-1) in the control group). AD increased after antihypertensive therapy (VM: 2.8 × 10(-3 )mmHg(-1)-4.2 × 10(-3 )mmHg(-1) (p = 0.001); BA 3.3 × 10(-3 )mmHg(-1)-4.6 × 10(-3 )mmHg(-1) (p < 0.01)). In both treatment groups AD returned to a level comparable with the normal control group (p = 0.81) after 6 months.

CONCLUSIONS

In patients with essential hypertension and LVH, AD was lower than in matched normal controls. Despite the opposing pharmacological mechanisms utilised across the treatment groups, the improvement in AD was similar, suggesting that blood pressure reduction per se may be more important than RAAS and SNS inhibition for the improvement of aortic remodelling.

Update on the use of trandolapril in the management of cardiovascular disorders

Trandolapril is a well known angiotensin converting enzyme (ACE) inhibitor with many cardiovascular (CV) indications. The objectives of this article are to review the pharmacokinetics and pharmacodynamics properties of trandolapril and to focus on its clinical relevance in cardiovascular medicine. Various populations have been studied in large clinical trials including patients with congestive heart failure (CHF) after an acute myocardial infarction (AMI), diabetics, patients with hypertension (HTN), stable coronary artery disease (CAD) and prevention of proteinuria. Long-term treatment with trandolapril in patients with reduced left ventricular function soon after AMI significantly reduced the risk of overall mortality, mortality from CV causes, sudden death, and the development of severe CHF. Treatment with trandolapril after AMI complicated by left ventricular dysfunction appears to be of considerable importance in patients with diabetes mellitus by saving lives and substantially reducing the risk of progression to severe CHF as well. Moreover, trandolapril reduces progression to proteinuria in high-risk patients. Some of the advantages of trandolapril over other ACE inhibitors are the wide spectrum of patient populations studied, the well established dosage and its proven trough-to-peak effect ratios permitting a safe once-a-day administration.

Ramipril reduces large-artery stiffness in peripheral arterial disease and promotes elastogenic remodeling in cell culture

Ramipril improves cardiovascular outcome in patients with peripheral arterial disease; however, the precise mechanisms of benefit remain to be elucidated. The effect of ramipril on large-artery stiffness in patients with peripheral arterial disease was examined. In addition, we determined the effect of ramiprilat on extracellular matrix from human aortic smooth muscle cell culture. Forty patients with peripheral arterial disease were randomized to receive ramipril, 10 mg once daily or placebo for 24 weeks. Arterial stiffness was assessed globally via systemic arterial compliance and augmentation index (carotid tonometry and Doppler velocimetry), and regionally via carotid-femoral pulse wave velocity. Angiotensin-converting enzyme inhibition increased arterial compliance by 0.10+/-0.02 mL/mm Hg, (P<0.001, all probability values relative to placebo) and reduced pulse wave velocity by 1.7+/-0.2 m/s (P<0.001), augmentation index by 4.1+/-0.3% (P<0.001), and systolic blood pressure by 5+/-1 mm Hg (P<0.001). Ramipril did not reduce mean arterial pressure significantly compared with placebo (P=0.59). In cell culture, ramiprilat decreased collagen deposition by >50% and increased elastin and fibrillin-1 deposition by >3- and 4-fold respectively (histochemistry and immunohistochemistry). Fibrillin-1 gene expression was increased 5-fold (real-time reverse-transcriptase polymerase chain reaction). Ramiprilat also reduced gene and protein (Western) expression of both matrix metalloproteinase (MMP)-2 and MMP-3. In conclusion, ramipril promoted an elastogenic matrix profile that may contribute to the observed clinical reduction in large-artery stiffness and carotid pressure augmentation, which occurred independently of mean arterial blood pressure reduction in patients with peripheral arterial disease.

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.

Arterial stiffness and the renin-angiotensin-aldosterone system

Arterial stiffness has recently been recognised as an independent risk factor for cardiovascular morbidity and mortality in hypertension. Many of the complications seen with angiotensin II (Ang II) excess or hyperaldosteronism--an increased event rate, left ventricular hypertrophy, endothelial dysfunction and target organ damage--are also associated with arterial stiffness. It is possible that reduced arterial compliance may be one mechanism whereby increased activity of the renin-angiotensin-aldosterone system (RAAS) produces adverse vascular effects. Common pathophysiological processes, altered collagen turnover and increased fibrosis may underlie both arterial stiffness and RAAS-associated vascular damage. While it is recognised that patients with hyperaldosteronism have increased arterial stiffness, the role of the RAAS in modulating arterial compliance in essential hypertension and in normotensive subjects is less clear cut. There is, however, more consistent data which show that drugs that interfere with Ang II or aldosterone, namely angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and aldosterone antagonists, all reduce arterial stiffness. In many cases, this is to a greater extent than predicted from the extent of reduction in blood pressure (BP), suggesting a role for RAAS in vascular stiffness in hypertensive subjects. There is also evidence that combined ACE inhibitors (ACE-Is) and ARBs may have an additive effect in reducing stiffness. The reduction in cardiovascular mortality in end-stage renal disease patients treated with ACE-Is was preferentially seen in those who had reduced arterial stiffness. These data suggest that, in addition to regulation of vascular biology and BP, the RAAS is an important determinant of arterial stiffness in health and, more particularly, in disease.

Trandolapril: a newer angiotensin-converting enzyme inhibitor

BACKGROUND

Trandolapril is a newer angiotensin-converting enzyme (ACE) inhibitor that is approved by the US Food and Drug Administration for the treatment of hypertension and for use in stable patients who have evidence of left ventricular (LV) systolic dysfunction or symptoms of chronic heart failure within the first 2 days after an acute myocardial infarction (AMI). The fixed-dose combination of trandolapril and verapamil extended release (ER) is approved for the treatment of hypertension only.

OBJECTIVE

The purpose of this article was to review the pharmacology, pharmacokinetics, clinical efficacy, and safety profile of trandolapril as monotherapy and in fixed-dose combination with verapamil ER.

METHODS

Relevant studies were identified through a MEDLINE/PubMed search of the English-language literature published between January 1983 and August 2002 and a review of the bibliographies of identified articles.

RESULTS

Trandolapril has a sufficient duration of inhibition of plasma ACE activity to allow once-daily dosing. It is converted by esterases to the active trandolaprilat metabolite, with mean terminal disposition half-lives of < 1 and approximately 75 hours for the prodrug and metabolite, respectively. In comparative trials in the management of hypertension, trandolapril 1 to 4 mg/d was statistically indistinguishable from or superior to captopril 100 mg/d, enalapril 10 or 20 mg/d, hydrochlorothiazide (HCTZ) 25 mg/d, nifedipine ER 30 or 40 mg/d, nitrendipine 20 mg/d, perindopril 4 mg/d, and verapamil ER 120 to 240 mg/d. In the Trandolapril Cardiac Evaluation, trandolapril also significantly reduced all-cause mortality, cardiovascular mortality, sudden death, and progression to severe chronic heart failure in patients with evidence of LV systolic dysfunction after AMI. In comparative trials in the management of hypertension, the combination of trandolapril 1 or 2 mg/d and verapamil ER 180 mg/d was statistically indistinguishable from or superior to the combinations of atenolol 50 or 100 mg/d plus chlorthalidone 12.5 or 25 mg/d, captopril 50 mg/d plus HCTZ 25 mg/d, lisinopril 20 mg/d plus HCTZ 12.5 mg/d, and metoprolol 100 mg/d plus HCTZ 12.5 mg/d. The most common adverse effects of trandolapril monotherapy in clinical trials of < or = 1 year's duration included cough, dizziness, and diarrhea (frequency < or = 1.9%). The most common adverse effects of trandolapril/verapamil ER therapy in clinical trials of < or = 1 year's duration included first-degree atrioventricular block, bradycardia, constipation, cough, diarrhea, dizziness, fatigue, and dyspnea (frequency < or = 4.6%). Based on the literature search, there are no published pharmacoeconomic evaluations of trandolapril alone or combined with verapamil ER in the US health care setting.

CONCLUSIONS

Based on the literature, trandolapril is a well-tolerated and effective antihypertensive agent, whether used alone or in combination with verapamil ER. These products may be valuable in patients with LV systolic dysfunction after AMI, although the combination product is approved for the management of hypertension only.

Early carotid atherosclerosis in normotensive severe obese premenopausal women with low DHEA(S)

The aim of this study was to investigate the direct involvement of hyperinsulinaemia, DHEA and DHEA-S [DHEA(S)] in severe obesity in early carotid atherosclerosis, measured as intima-media thickness (IMT). Seventeen normotensive premenopausal women with very high BMI (43.5 +/- 1.6 kg/m2) were recruited for the study. Six women were also evaluated 12 months after laparoscopic adjustable silicone gastric banding (LASGB). Dietary intake, fasting plasma lipid profile, glycemic and insulinemic response to the OGTT, adrenal secretion, at baseline and after ACTH stimulation test, were measured. IMT, common carotid diameter (CD) and left ventricular mass index (LVMi) were measured by B-mode echotomography. All obese subjects showed higher fasting and stimulated insulin levels, but lower DHEA(S) levels than controls, showing a negative correlation between both fasting and stimulated insulin and DHEA(S), either at baseline or after ACTH testing. IMT was higher (p < 0.05) than controls, with a positive correlation with stimulated insulin (p < 0.05) and a strong negative correlation with DHEA(S) (p < 0.001). In a multiple linear regression analysis, insulin response to OGTT maintained an association with DHEA(S) independent of fasting insulin, while DHEA maintained the association with IMT independent of stimulated insulin (p < 0.0001). In the six patients evaluated 12 months after LASGB, fasting insulin levels decreased, while DHEA(S) levels increased (p < 0.05). In conclusion, an early cardiovascular involvement was detected in this group of severe obese with hyperinsulinaemia and low DHEA(S), even in the absence of other well known CVD risk factors.

The effect of antihypertensive drugs on vascular compliance

Measurement of vascular compliance has assumed increasing importance as a marker of early disease of the vascular wall, a predictor of future vascular disease, and a way to monitor the effects of vasoactive agents on arterial wall stiffness. Vascular compliance can be estimated by several methods: measurement of the pulse pressure, or pulse pressure-stroke volume ratio; analysis of the systolic pulse wave augmentation index and the diastolic pulse wave contour; ultrasonic echo-tracking; and MRI. Because few comparative studies have been done, the physiologic significance of the measures of compliance obtained by each method is uncertain. Antihypertensive drugs may improve vascular compliance by reducing blood pressure, relaxing vascular smooth muscle, or promoting long-term effects on vascular smooth muscle and cardiomyocyte growth and remodeling. Angiotensin converting enzyme (ACE) inhibitors have been reported to improve vascular compliance in nearly all studies, suggesting a beneficial class effect independent of blood pressure reduction. Favorable changes in the vascular wall-lumen ratio of small vessels from subcutaneous gluteal biopsy specimens after treatment with ACE inhibitors and the persistence of improved vascular compliance after withdrawal of therapy indicate that these agents may produce long-term vascular remodeling. Although few studies have been done, angiotensin II receptor antagonists improve vascular compliance, possibly by blocking angiotensin II-mediated cell proliferation and increasing apoptosis via unopposed AT1 receptor stimulation. In contrast, calcium antagonists and beta-blockers have variable effects on vascular compliance, although beta-blockers with intrinsic sympathomimetic activity improve vascular compliance. Diuretics have little effect on vascular compliance beyond their blood pressure-lowering actions, except for spironolactone, which by improving vascular compliance may have contributed to the reduction in heart failure mortality seen in the Randomized Aldactone Evaluation Study.

Reversal of pathophysiologic changes with long-term lisinopril treatment in isolated systolic hypertension

The purpose of this study was to evaluate in a prospective, double-blind, placebo-controlled study the effect of long-term (2-year) lisinopril treatment on cardiovascular end-organ damage in patients with previously untreated isolated systolic hypertension (ISH). All patients with ISH were derived from a population screening program. End-organ damage measurements, done initially and after 6 and 24 months of treatment, included measurements of aortic distensibility and echocardiographic left ventricular mass index (LVMI) and diastolic function. Blood pressure was measured by office and ambulatory measurements. Of the 97 subjects with ISH selected from the screening, 62 (30 lisinopril) completed the study according to protocol. Office blood pressure decreased in both groups, but ambulatory results significantly decreased with lisinopril-treatment only. Aortic distensibility increased significantly with lisinopril, as opposed to a decrease in placebo-treated subjects. The main effect of increased distensibility occurred between 6 and 24 months, whereas ambulatory blood pressure changed mainly in the first 6 months of treatment. LVMI decreased in both treatment groups, with a significantly higher reduction in lisinopril-treated subjects. Left ventricular diastolic function showed no significant changes in either group. The vascular pathophysiologic alterations of ISH-a decreased aortic distensibility-can be improved with long-term lisinopril treatment, whereas values deteriorate further in placebo-treated subjects. These results, in one of the first studies including subjects with previously untreated ISH only, indicate that lisinopril treatment might favorably influence the cardiovascular risk of ISH.

Effects of antihypertensive agents on the left ventricle: clinical implications

Hypertensive heart disease (HHD) is characterized by left ventricular hypertrophy (LVH), alterations of cardiac function, and coronary flow abnormalities. LVH is an independent cardiovascular risk factor related to cardiovascular complications in patients with hypertension. Therefore, a decrease in left ventricular mass is a therapeutic goal in these patients. The effect of the different antihypertensive agents on LVH regression has been studied in nearly 500 clinical trials. Most studies conclude that there is regression of LVH after significant decrease in blood pressure with most commonly prescribed antihypertensive agents. However, the ability to regress LVH is different between antihypertensive drug classes. ACE inhibitors and calcium channel antagonists are more potent in reducing left ventricular mass than beta-blockers, with diuretics falling in the intermediate group. Recent data suggest that angiotensin AT(1) receptor antagonists reduce left ventricular mass to a similar extent as ACE inibitors or calcium channel antagonists. Although a large number of studies have established that reversal of LVH decreases the occurrence of adverse cardiovascular events in patients with hypertension, the hypothesis that LVH regression is beneficial has not yet been conclusively proven. On the other hand, the time has come to revisit the current management of HHD simply focused on controlling blood pressure and reducing left ventricular mass. In fact, it is necessary to develop new approaches aimed to repair myocardial structure and protect myocardial perfusion and function and, in doing so, to reduce in a more effective manner, adverse risk associated with HHD. The identification of genes involved in both the process of HHD and the response to therapy may be critical for the development of these new approaches. This article will review briefly the available data on the effects of antihypertensive agents on HHD. In addition, the emerging new concepts on the pharmacology of hypertensive myocardial remodeling and the pharmacogenetic basis of the treatment of HHD will be also considered.

Time course of the effects of temocapril on cardiovascular structure and function in patients with essential hypertension

To investigate the time course of cardiovascular structural changes in patients with essential hypertension after angiotensin-converting enzyme (ACE) inhibition, we determined left ventricular structure, minimal vascular resistance in the forearm as an index of resistance vessel structure and stiffness beta of carotid artery in 15 essential hypertensive subjects during a placebo period and after 2, 6, and 12 months of temocapril treatment. Blood pressure decreased within 2 weeks, and the antihypertensive effects were noted throughout the 12-month administration period. Left ventricular mass index decreased significantly after 2 months (120+/-12 to 106+/-9 g/m2; p < 0.01) and was normalized after 12 months (88+/-6 g/m2). Postischemic minimal vascular resistance in the forearm decreased gradually from 2.1+/-0.5 to 1.6+/-0.4 PRU at month 12 of temocapril treatment. In contrast, increased stiffness index beta of carotid artery was not altered during a 1-year treatment period (11.4+/-4.9 to 11.6+/-3.8 at month 12 of treatment). These data indicated that the regression of structural changes of left ventricle and arterioles occurred gradually and progressively for 1-year treatment with ACE inhibition, but large arteries were not affected.

Distinct vasodilation, without reflex neurohormonal activation, induced by barnidipine in hypertensive patients

Barnidipine is a new 1,4-dihydropyridine calcium antagonist with a strong and long-lasting vasodilatory effect. In order to assess the haemodynamic profile of the antihypertensive effect of barnidipine, a randomized, double-blind study of barnidipine vs nitrendipine was performed in 24 patients with mild to moderate essential hypertension. Following an initial 4-week placebo period, patients whose sitting diastolic blood pressure (SiDBP) was between 95 and 114 mm Hg, and whose sitting systolic blood pressure was between 150 and 219 mm Hg, were randomized (2:1 ratio) to receive either barnidipine (10 mg) or nitrendipine (10 mg) once daily, for a 6-week double-blind period. Subsequently, patients with an SiDBP of less than 90 mm Hg continued for a second 6-week period with the same monotherapy, while patients with an SiDBP of 90 mm Hg or above received double the dose of antihypertensive treatment for the next 6 weeks. Two-dimensional M- and B-mode echocardiography with Doppler flowmetry was performed at the end of both the placebo and active treatment phases. Barnidipine and nitrendipine reduced blood pressure by the same degree (barnidipine: from 165 +/- 2/100 +/- 1 to 145 +/- 2/89 +/- 1 mm Hg, p < 0.01; nitrendipine: from 163 +/- 3/100 +/- 2 to 143 +/- 7/90 +/- 3 mm Hg, p < 0.01) as a result of peripheral vasodilation. This was not accompanied by reflex neurohormonal activation. Moreover, only in the group receiving barnidipine was a significant decrease in plasma noradrenaline observed, both when the patients were in the supine position (from 298 +/- 27 to 214 +/- 21 pg/ml, p < 0.05) and when they were upright (from 472 +/- 37 to 348 +/- 38 pg/ml, p < 0.05).

Differential responses of the heart and vasculature to chronic blood pressure reduction in essential hypertension

BACKGROUND

In subjects with hypertension, converting enzyme inhibitors and calcium entry blockers may decrease arterial stiffness independently of blood pressure changes, but the heterogeneity of response of the arterial tree has never been taken into account.

MATERIAL AND METHODS

In 31 subjects with hypertension, we determined through the use of Doppler echographic techniques the compliance and distensibility of the common carotid and femoral arteries and of the abdominal aorta, the radial artery wall thickness, and cardiac mass. In a double-blind randomized study, the converting enzyme inhibitor ramipril and the calcium entry blocker nitrendipine were studied and compared during 12 weeks treatment, then 4 weeks after treatment was stopped.

RESULTS

The two drugs caused significantly different plasma levels of active renin, angiotensin I, and norepinephrine but the same effects on blood pressure, cardiac mass, radial artery wall thickness, and stiffness indices. In contrast, the effect of treatment differed substantially according to the site of cardiovascular measurements. Although cardiac mass decreased significantly in parallel with blood pressure reduction, no change in radial artery wall thickness occurred. Carotid compliance and distensibility increased significantly, even after drug treatment was stopped, whereas little or no change was observed for the femoral artery and the abdominal aorta.

CONCLUSION

This study provides evidence that the changes in cardiovascular structure and function with ramipril and nitrendipine treatment are poorly influenced by their different mechanisms of action but highly dependent on the site of measurements. The results suggest that local autocrine-paracrine mechanisms act synergistically with blood pressure to produce cardiovascular changes.

Structure and in vitro function of human subcutaneous small arteries in mild heart failure

The structure and function of subcutaneous small arteries from patients with mild heart failure (n = 27) 6-43 mo after myocardial infarction were compared with vessels from healthy control subjects (n = 10). Patients were randomized to treatment with placebo or the angiotensin-converting enzyme inhibitor ramipril starting 3-10 days after myocardial infarction. Dissected arterial vessels were mounted on a wire myograph for measurement of morphology and isometric tension. Morphology was not different in arteries from the three groups. Responses to norepinephrine, angiotensin II, and electrical field stimulation were similar in arteries from placebo-treated patients with mild heart failure and control subjects. Similarly, endothelium-dependent and -independent relaxation was normal in arteries from patients with mild heart failure. Ramipril therapy was associated with functional alterations: vasoconstrictor responses to norepinephrine and angiotensin II were significantly enhanced compared with placebo (P < 0.001). These data suggest that vascular structure and function are not different in vitro in subcutaneous arteries from placebo-treated patients with mild heart failure. Angiotensin-converting enzyme inhibitor therapy is associated with enhanced vasoconstriction to norepinephrine and angiotensin II, which may reflect upregulation of receptor-mediated events.

The importance of arterial compliance in cardiovascular drug therapy

Arterial compliance, defined as a change in dimension in response to a given change in stress, is becoming an increasingly important clinical parameter. Related concepts, such as distensibility, elasticity, and stiffness, and more traditional concepts such as resistance, afterload, and impedance need to be differentiated from compliance, although they are frequently (inappropriately) used interchangably. Many studies cannot differentiate between compliance changes due to a drug's effect on blood pressure and those due to a drug's effect on vessel wall integrity. This differentiation is important because a more physiologic therapy, one that benefits pulsatile and nonpulsatile flow, should be of greater clinical benefit than a therapy that only lowers blood pressure. A number of methods have been used to estimate compliance, but to date there is no generally agreed-on best method. There also are no longitudinal studies that relate abnormal compliance and drug effects to outcome. Nonetheless, patients at risk from a variety of disease states, such as hypertension, diabetes mellitus, and hypercholesterolemia, may benefit from earlier recognition of abnormal compliance. Earlier recognition may lead to interventions that would reduce their risk. This review includes a discussion of compliance and related estimates of blood vessel function and attempts to summarize the data currently available regarding the effects of cardioactive drugs on arterial compliance.

Long-term treatment with angiotensin I-converting enzyme inhibitors attenuates the loss of cardiac beta-adrenoceptor responses in rats with chronic heart failure

BACKGROUND

Cardiac contractile force in response to beta-adrenoceptor agonists and beta-adrenergic receptor density are decreased in failing human hearts. The effects of angiotensin I-converting enzyme (ACE) inhibitor on cardiac responsiveness to beta-adrenergic stimulation in failing hearts are not established. The present study was undertaken to determine whether ACE inhibitor may improve cardiac beta-adrenergic responsiveness in animals with chronic heart failure (CHF).

METHODS AND RESULTS

CHF was induced by left coronary artery ligation in rats. Cardiac output and stroke volume indices decreased 12 weeks after the operation. In sham-operated rats, dobutamine and isoprenaline increased cardiac output and stroke volume indices. In contrast, cardiac output and stroke volume responses to dobutamine and isoprenaline were severely blunted in the CHF rat. Cardiac beta 1-adrenergic receptor density was decreased while its dissociation constant (Kd) was not altered in the viable tissue of the left ventricle of the CHF rat, which is consistent with beta-adrenergic receptor downregulation. Cardiac norepinephrine content decreased in the CHF rats. Rats were treated orally with ACE inhibitors, 3 mg/kg trandolapril or 10 mg/kg enalapril once daily, or 5 mg/kg captopril twice daily from the 2nd to the 12th weeks after the operation. Treatment with ACE inhibitors attenuated the reduction in cardiac output and stroke volume indices and improved the inotropic response to dobutamine and isoprenaline and reversed partially the cardiac norepinephrine content in the CHF rat. ACE inhibitor treatment also attenuated the reduction in beta 1-adrenergic receptor density in the viable tissue of the left ventricle of the CHF rat.

CONCLUSIONS

The results suggest that ACE inhibitor treatment attenuates the blunting of cardiac responses to beta-adrenergic agonists in the CHF rat and that one of the mechanisms underlying this effect is prevention of cardiac beta 1-adrenergic receptor downregulation.

Effects of one-year treatment with rilmenidine on systemic hypertension-induced left ventricular hypertrophy in hypertensive patients

In patients with essential hypertension, left ventricular hypertrophy (LVH) increases the risk for cardiovascular morbidity and mortality. Thus its reversal represents one of the principal end-points of antihypertensive treatment. We assessed the cardiovascular effects of 1-year antihypertensive treatment with rilmenidine (1 or 2 mg/day orally), a new oxazoline with a potent antihypertensive action that acts selectively through imidazoline-preferring receptors. In 11 hypertensive patients (mean age, 49 +/- 2 years) with LVH, we measured systemic hemodynamics, large artery compliance, cardiac anatomy, and endocrine function. Patients underwent M-mode and 2-dimensional echocardiography as well as Doppler and peripheral pulsed Doppler flowmetry, determination of plasma atrial natriuretic factor (ANF) levels and renin activity (PRA), and of 24-hour urinary electrolyte and creatinine excretion in control conditions (systolic/diastolic blood pressure, 148 +/- 3/102 +/- 1 mm Hg), 4 weeks after blood pressure normalization (131 +/- 2/84 +/- 2 mm Hg; p < 0.01), after 1 year of satisfactory antihypertensive treatment (142 +/- 3/90 +/- 1 mm Hg; p < 0.01) and, finally, 1 month after therapy withdrawal (155 +/- 3/106 +/- 2 mm Hg; difference not significant [NS]). One-year of rilmenidine treatment induced an improvement in brachial artery compliance (from 0.92 +/- 0.06 to 1.16 +/- 0.08 cm4/dyne; p < 0.05), which persisted after withdrawal of treatment (1.17 +/- 0.06 cm4/dyne; p < 0.05). LVH was reversed after 1 year of rilmenidine treatment (from 152 +/- 5 to 131 +/- 4 g/m2 body surface area; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of trandolapril on the sympathetic tone and reactivity in systemic hypertension

Hemodynamic and autonomic evaluations were carried out after 2-3 weeks of treatment with placebo and at the end of 4 weeks of treatment with an angiotensin converting enzyme (ACE) inhibitor, trandolapril, 2 mg/day in 18 hypertensive patients (average age, 48 +/- 2 years) of either sex. This treatment lowered the mean arterial pressure in the whole group from 112 to 105 mm Hg (p < 0.05) without significant changes in basal heart rate or norepinephrine (NE) and epinephrine plasma levels. Based on daytime ambulatory blood pressure monitoring, the patients were separated into 2 equal groups of 9 patients: the better responders (R), with an average decrease in mean arterial pressure of 12 mm Hg, and the lesser responders (NR), with an average fall of mean arterial pressure of 2 mm Hg. Before treatment, the R group had a higher resting heart rate, a lower cardiac output (-16%), and a higher peripheral resistance (+22%) than the NR group (difference not significant). Moreover, the R group was also observed to have a 33% higher plasma NE level (p < 0.05) in the supine position, associated with a 52% higher NE response to standing (p < 0.05), and a 40% lower number of beta-adrenergic receptors on lymphocytes, suggesting a higher sympathetic tone and reactivity in that group. Following treatment with the ACE inhibitor, heart rate and plasma NE levels were not altered significantly in either group, suggesting a blunting of the baroreflex response concomitant with the lowered blood pressure, especially in the R group.(ABSTRACT TRUNCATED AT 250 WORDS)

Trandolapril in hypertension: overview of a new angiotensin-converting enzyme inhibitor

Trandolapril is a new angiotensin-converting enzyme (ACE) inhibitor that has been extensively investigated in vitro, in animals, in normal volunteers, and in hypertensive patients. It has been shown to exert all the effects typical for the class of ACE inhibitors, and has a marked impact on the reversal of structural hypertrophy of the myocardium and the arterial wall. Trandolapril is a prodrug that must be hydrolyzed to its active metabolite, trandolaprilat. This latter compound exhibits a particularly high affinity for converting enzyme, which results in a slow dissociation and one of the longest durations of action of any converting enzyme inhibitor known so far. Trandolapril reduces blood pressure consistently throughout the 24-hour period following intake. Accordingly, trandolapril, more than any other drug of its class, can be considered a true, once-a-day antihypertensive drug.

Effects of trandolapril on vascular morphology and function during the established phase of systemic hypertension in the spontaneously hypertensive rat

The aim of this study was to determine the morphologic and functional vascular changes occurring following 4 weeks of treatment with the angiotensin-converting enzyme inhibitor trandolapril in the spontaneously hypertensive rat (SHR) in the established phase of hypertension. At the dosage used, 0.4 mg/kg orally, trandolapril decreased blood pressure of the SHR by 15-18% compared with that of the control animals. Immediately before the end of treatment, the following changes from control values were observed: (1) 9, 11, and 12% reductions for myocardial hypertrophy and the media thickness of the thoracic aorta and femoral arteries, respectively; and (2) an increase in the compliance of the resistance arteries, demonstrated by a shift to the right of the in vitro tension-diameter curves and a significant 22% increase in their normalized internal diameter, while their maximum contractile ability was significantly decreased. Following discontinuation of treatment, blood pressure levels remained significantly lower in the treated versus the control groups for up to 4 weeks after the last administration. At that time measurement of the studied parameters showed: (1) a rapid reversion to control values of the compliance of the resistance vessels; and (2) a slower progression, but in the same direction, in the parameters of cardiac and vascular hypertrophy. Thus, trandolapril, administered for a short period in the adult SHR, was able to reverse the cardiac and vascular morphologic changes present in this model of hypertension. Like the effect on blood pressure, these effects were slowly reversible at the end of treatment, whereas the functional consequences at the resistance artery level seemed to display a more rapid reversibility.