Assessment of captopril and nicardipine effects on chronic occlusive arterial disease of the lower extremity using Doppler ultrasound

Improved survival with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in chronic limb-threatening ischemia

OBJECTIVE

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) reduce the risk of cardiovascular events in patients with peripheral artery disease. However, their effect on limb-specific outcomes is unclear. The objective of this study was to assess the effect of ACE inhibitors/ARBs on limb salvage (LS) and survival in patients undergoing peripheral vascular intervention (PVI) for chronic limb-threatening ischemia (CLTI).

METHODS

The Vascular Quality Initiative registry was used to identify patients undergoing PVI for CLTI between April 1, 2010, and June 1, 2017. Patients with complete comorbidity, procedural, and follow-up limb and survival data were included. Propensity score matching was performed to control for baseline differences between the groups. LS, amputation-free survival (AFS), and overall survival (OS) were calculated in matched samples using Kaplan-Meier analysis.

RESULTS

A total of 12,433 limbs (11,331 patients) were included. The ACE inhibitors/ARBs group of patients had significantly higher prevalence of coronary artery disease (31% vs 27%; P < .001), diabetes (67% vs 57%; P < .001), and hypertension (94% vs 84%; P < .001) and lower incidence of end-stage renal disease (7% vs 12%; P < .001). Indication for intervention was tissue loss in 64% of the ACE inhibitors/ARBs group vs 66% in the no ACE inhibitors/ARBs group (P = .005). Postmatching survival analysis at 5 years showed improved OS (81.8% vs 79.9%; P = .01) and AFS (73% vs 71.5%; P = .04) with ACE inhibitors/ARBs but no difference in LS (ACE inhibitors/ARBs, 88.3%; no ACE inhibitors/ARBs, 88.1%; P = .56). After adjustment for multiple variables in a Cox regression model, ACE inhibitors/ARBs were associated with improved OS (hazard ratio, 0.89; 95% confidence interval, 0.80-0.99; P = .03) and AFS (hazard ratio, 0.92; 95% confidence interval, 0.84-0.99; P = .04).

CONCLUSIONS

ACE inhibitors/ARBs are independently associated with improved survival and AFS in patients undergoing PVI for CLTI. LS rates remained unaffected. Further research is required to investigate the use of ACE inhibitors/ARBs in this population of patients, especially CLTI patients with other indications for therapy with ACE inhibitors/ARBs.

Angiotensin Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers (ACEI/ARB) are Associated with Improved Limb Salvage after Infrapopliteal Interventions for Critical Limb Ischemia

BACKGROUND

Angiotensin-converting enzyme Inhibitors and Angiotensin II Receptor Blockers (ACEI/ARB) reduce the risk of cardiovascular events and mortality in patients with peripheral arterial disease (PAD). However, their effect on limb-specific outcomes is unclear. The objective of this study is to assess the effect of ACEI/ARB on patency and limb salvage in patients undergoing interventions for critical limb ischemia (CLI).

METHODS

Patients undergoing infrainguinal revascularization for CLI (Rutherford 4-6) between 06/2001 and 12/2014 were retrospectively identified. Primary Patency (PP), Secondary Patency (SP), Limb Salvage (LS), major adverse cardiac events (MACE), and survival rates were calculated using Kaplan-Meier. Multivariate analysis was performed using Cox regression.

RESULTS

A total of 755 limbs in 611 patients (311 ACEI/ARB, 300 No ACEI/ARB) were identified. Hypertension (86% vs. 70%, P < 0.001), diabetes (68% vs. 55%, P = 0.001) and statin use (61% vs. 45%, P < 0.001) were significantly greater in the ACEI/ARB group. Interventions were performed mostly for tissue loss (83% ACEI/ARB vs. 84% No ACEI/ARB, P = 0.73). Comparing ACEI/ARB versus No ACEI/ARB, in femoropopliteal interventions, 60-month PP (54% vs. 55%, P = 0.47), SP (76% vs. 75%, P = 0.83) and LS (84% vs. 87%, P = 0.36) were not significantly different. In infrapopliteal interventions, 60-month PP (45% vs. 46%, P = 0.66) and SP (62% vs. 75%, P = 0.96) were not significantly different. LS was significantly greater in ACEI/ARB (75%), as compared to No ACEI/ARB (61%) (P = 0.005). Cox regression identified diabetes (HR 2.4 (1.4-4.1), P = 0.002), ESRD (HR 3.5 (2.1-5.7), P < 0.001), hypertension (HR 0.4 (0.2-0.6), P < 0.001), and ACEI/ARB (HR 0.6 (0.4-0.9), P = 0.03), as factors independently associated with LS after infrapopliteal interventions. Freedom from MACE (ACEI/ARB 37% vs. 32%, P = 0.82) and overall survival (ACEI/ARB 42% vs. 35% No ACEI/ARB, P = 0.84) were not significantly different.

CONCLUSIONS

ACEI/ARB is associated with improved limb salvage in CLI patients undergoing infrapopliteal interventions, but not after femoropopliteal interventions. ACEI/ARB had no impact on patency rates. They were also associated with a trend toward improved survival and freedom from MACE. Our findings suggest that the use of ACEI/ARB may improve outcomes in the high-risk CLI patient population.

The potential role of angiotensin-converting enzyme inhibition in peripheral arterial disease

Peripheral arterial disease (PAD) is associated with significant morbidity and mortality, and yet remains under-recognized and under-treated. Atherosclerosis is the most common cause of lower extremity PAD and pharmacological interventions that alter this central pathogenic role of atherosclerosis may alter the natural history of PAD. There is growing evidence that the renin-angiotensin system (RAS) is a significant mediator of this disease process and that treatment with angiotensin-converting enzyme (ACE) inhibitors is associated with vasculoprotective effects that are independent of the antihypertensive properties of these agents. Numerous lines of evidence suggest that ACE inhibitors directly inhibit the atherosclerotic process and improve vascular endothelial function. In patients with PAD, ACE inhibitors have been shown to improve peripheral circulation as measured by peripheral arterial blood pressure and by increases in peripheral blood flow. Preliminary evidence suggests that ACE inhibitors might improve clinical symptoms in patients with PAD. Recent evidence has confirmed that ACE inhibition is associated with a decrease in morbidity and mortality in patients with arterial disease without left ventricular dysfunction; this benefit was at least as great for the subset of patients with PAD. Overall, these data support a significant role for the RAS in the pathogenesis of all atherosclerotic diseases (including PAD) and suggest that the benefit is independent of the blood pressure lowering properties of these agents. These studies suggest that ACE inhibitor therapy should be considered in the routine management of individuals with PAD, regardless of whether they have hypertension or left ventricular dysfunction.

Angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use is associated with reduced major adverse cardiovascular events among patients with critical limb ischemia

Angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) are recommended for secondary prevention in peripheral artery disease, but their effectiveness in patients with critical limb ischemia (CLI) is uncertain. We reviewed 464 patients with CLI who underwent diagnostic angiography or endovascular intervention from 2006–2013 at a multidisciplinary vascular center. ACEI or ARB use was assessed at the time of angiography. Major adverse cardiovascular events (MACE), mortality, and major adverse limb events (MALE) were assessed during three-year follow-up. Propensity weighting was used to adjust for baseline differences between patients taking and not taking ACEIs or ARBs. ACEIs or ARBs were prescribed to 269 (58%) patients. Patients prescribed ACEIs or ARBs had more baseline comorbidities including diabetes and hypertension ( p<0.05). Patients prescribed ACEIs or ARBs had lower three-year unadjusted rates of MACE (40% versus 47%) and mortality (33% versus 43%). After propensity weighting, ACEI or ARB use was associated with significantly lower rates of MACE (hazard ratio [HR] 0.76, 95% confidence interval [CI] 0.58–0.99, p=0.04) and overall mortality (HR 0.71, 95% CI 0.53–0.95, p=0.02). There was no significant association between ACEI or ARB use and MALE (HR 0.97, 95% CI 0.69–1.35, p=0.2) or major amputation (HR 0.74, 95% CI 0.47–1.18, p=0.1). ACEI/ARB use is associated with lower MACE and mortality in patients with CLI, but there was no effect on limb-related outcomes.

Treatment of hypertension in peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) causes considerable morbidity and mortality. Hypertension is a risk factor for PAD. Treatment for hypertension must be compatible with the symptoms of PAD. Controversy regarding the effects of beta-adrenoreceptor blockade for hypertension in patients with PAD has led many physicians to stop prescribing beta-adrenoreceptor blockers. Little is known about the effects of other classes of anti-hypertensive drugs in the presence of PAD. This is the second update of a Cochrane review first published in 2003.

OBJECTIVES

To determine the effects of anti-hypertensive drugs in patients with both raised blood pressure and symptomatic PAD in terms of the rate of cardiovascular events and death, symptoms of claudication and critical leg ischaemia, and progression of atherosclerotic PAD as measured by ankle brachial index (ABI) changes and the need for revascularisation (reconstructive surgery or angioplasty) or amputation.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Cochrane Peripheral Vascular Diseases Group Specialised Register (last searched March 2013) and CENTRAL (2013, Issue 2).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of at least one anti-hypertensive treatment against placebo or two anti-hypertensive medications against each other, with interventions lasting at least one month. Trials had to include patients with symptomatic PAD.

DATA COLLECTION AND ANALYSIS

Data were extracted by one author (DAL) and checked by the other (GYHL). Potentially eligible studies were excluded when the results presentation prevented adequate extraction of data and enquiries to authors did not yield raw data.

MAIN RESULTS

Eight RCTs were included with a total of 3610 PAD patients. Four studies compared a recognised class of anti-hypertensive treatment with placebo and four studies compared two anti-hypertensive treatments with each other. Studies were not pooled due to the variation of the comparisons and the outcomes presented. Overall the quality of the available evidence was unclear, primarily as a result of a lack of detail in the study reports on the randomisation and blinding procedures and incomplete outcome data. Two studies compared angiotensin converting enzyme (ACE) inhibitors against placebo. In one study there was a significant reduction in the number of cardiovascular events in patients receiving ramipril (odds ratio (OR) 0.72, 95% confidence interval (CI) 0.58 to 0.91; n = 1725). In the second trial using perindopril (n = 52) there was a marginal increase in claudication distance but no change in ABI and a reduction in maximum walking distance. A trial comparing the calcium antagonist verapamil versus placebo in patients undergoing angioplasty (n = 96) suggested that verapamil reduced restenosis (per cent diameter stenosis (± SD) 48.0% ± 11.5 versus 69.6% ± 12.2; P < 0.01), although this was not reflected in the maintenance of a high ABI (0.76 ± 0.10 versus 0.72 ± 0.08 for verapamil versus placebo). Another study (n = 80) demonstrated no significant difference in arterial intima-media thickness (IMT) in men receiving the thiazide diuretic hydrochlorothiazide (HCTZ) compared to those receiving the alpha-adrenoreceptor blocker doxazosin (-0.12 ± 0.14 mm and -0.08 ± 0.13 mm, respectively; P = 0.66). A study (n = 36) comparing telmisartan to placebo found a significant improvement in maximum walking distance at 12 months with telmisartan (median (interquartile range (IQR)) 191 m (157 to 226) versus 103 m (76 to 164); P < 0.001) but no differences in ABI (median (IQR) 0.60 (0.60 to 0.77) versus 0.52 (0.48 to 0.67)) or arterial IMT (median (IQR) 0.08 cm (0.07 to 0.09) versus 0.09 cm (0.08 to 0.10)). Two studies compared the beta-adrenoreceptor blocker nebivolol with either the thiazide diuretic HCTZ or with metoprolol. Both studies found no significant differences in intermittent or absolute claudication distance, ABI, or all-cause mortality between the anti-hypertensives. A subgroup analysis of PAD patients (n = 2699) in a study which compared a calcium antagonist-based strategy (verapamil slow release (SR) ± trandolapril) to a beta-adrenoreceptor blocker-based strategy (atenolol ± hydrochlorothiazide) found no significant differences in the composite endpoints of death, non-fatal myocardial infarction or non-fatal stroke with or without revascularisation (OR 0.90, 95% CI 0.76 to 1.07 and OR 0.96, 95% CI 0.82 to 1.13, respectively).

AUTHORS' CONCLUSIONS

Evidence on the use of various anti-hypertensive drugs in people with PAD is poor so that it is unknown whether significant benefits or risks accrue. However, lack of data specifically examining outcomes in PAD patients should not detract from the overwhelming evidence on the benefit of treating hypertension and lowering blood pressure.

Randomized clinical trial of angiotensin-converting enzyme inhibitor, ramipril, in patients with intermittent claudication

Background

The aim was to investigate the effect of ramipril on clinical parameters in patients with peripheral arterial disease.

Methods

Patients with intermittent claudication were randomized to receive ramipril or placebo for 24 weeks in a double-blind study. Outcome measures were walking distance, arterial stiffness measurement and quality of life (QoL).

Results

A total of 33 patients were included (25 men; mean(s.d.) age 64·6(7.8) years); 14 received ramipril and 19 placebo. After 24 weeks, ramipril improved maximum treadmill walking distance by an adjusted mean (95 per cent confidence interval, c.i.) of 131 (62 to 199) m (P = 0·001), improved treadmill intermittent claudication distance by 122 (56 to 188) m (P = 0·001) and improved patient-reported walking distance by 159 (66 to 313) m (P = 0·043) compared with placebo. Ramipril reduced carotid femoral pulse wave velocity by –1·47 (95 per cent c.i. –2·40 to –0·57) m/s compared with placebo (P = 0·002). Resting ankle : brachial pressure index (ABPI) improved slightly in both ramipril and placebo groups (0·02 (95 per cent c.i. –0·08 to 0·11) versus 0·03 (–0·05 to 0·10); P = 0·830). Ramipril had a slight, non-significant effect on QoL physical domains compared with placebo.

Conclusion

Ramipril improved walking distance in patients with claudication; however, this improvement was not related to improved ABPI but might have been due to ramipril reducing arterial stiffness. Registration number: NCT01037530 (http://www.clinicaltrials.gov).

Treatment of hypertension in peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) causes considerable morbidity and mortality. Hypertension is a risk factor for PAD. Treatment for hypertension must be compatible with the symptoms of PAD. Controversy regarding the effects of beta-blockade for hypertension in patients with PAD has led many physicians to stop prescribing beta-blockers. Little is known about the effects of other classes of anti-hypertensive drugs in the presence of PAD. This is an update of a Cochrane review first published in 2003.

OBJECTIVES

To determine the effects of anti-hypertensive drugs on cardiovascular events and death, symptoms of claudication, critical leg ischaemia, progression of PAD and revascularisation or amputation in people with hypertension and PAD SEARCH STRATEGY: The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched May 2009) and the Cochrane Central Register of Controlled Trials (The Cochrane Library 2009, Issue 2). The authors studied abstracts of cardiology meetings.

SELECTION CRITERIA

Randomised controlled trials of at least one anti-hypertensive treatment against placebo, or two anti-hypertensive medications against each other, with interventions lasting at least one month. Trials had to include patients with symptomatic PAD.

DATA COLLECTION AND ANALYSIS

Data were extracted by one author (DAL) and checked by the other (GYHL). Eligible studies were excluded when results presentation prevented adequate extraction of data and enquiries to authors did not yield raw data.

MAIN RESULTS

Four studies were included. Two compared ACE inhibitors against placebo. In the HOPE study there was a significant reduction in the number of cardiovascular events in 168 patients receiving ramipril (OR 0.72, 95% confidence interval 0.58 to 0.91). In the second trial using perindopril in a small numbers of patients, there was a marginal increase in claudication distance but no change in ankle brachial pressure index (ABPI) and a reduction in maximum walking distance.The third trial in patients undergoing angioplasty suggested that the calcium antagonist verapamil reduced restenosis, although this was not reflected in the maintenance of a high ABPI. Another small study demonstrated no significant difference in arterial intima-media thickness with men receiving the thiazide diuretic hydrochlorathiazide compared to those receiving the alpha-adrenoreceptor blocker doxazosin.

AUTHORS' CONCLUSIONS

Evidence on various anti-hypertensive drugs in people with PAD is poor so that it is unknown whether significant benefits or risks accrue from their use. Lack of data specifically examining outcomes in PAD patients should not detract from the compelling evidence of the benefit of treating hypertension and lowering blood pressure.

Pharmacologic therapy for intermittent claudication

Peripheral artery disease, defined as atherosclerosis in the lower extremities, affects nearly 8.5 million people in the United States. Due to the frequent asymptomatic manifestation of peripheral artery disease, diagnosis may be delayed and its true incidence underestimated. However, some patients may experience aching pain, numbness, weakness, or fatigue, a condition termed intermittent claudication. Peripheral atherosclerosis is associated with cardiovascular risk and physical impairment; therefore, treatment goals are aimed at decreasing cardiovascular risk, as well as improving quality of life. Little debate exists regarding the management of cardiovascular risk reduction, which consists of both antiplatelet therapy and risk factor modification. Despite recently published guidelines, the treatment of intermittent claudication is less well established and the management remains controversial and uncertain. Exercise remains the first-line therapy for intermittent claudication; however, pharmacologic treatment is often necessary. Although only two prescription drugs have been approved by the U.S. Food and Drug Administration for the treatment of intermittent claudication, several supplements and investigational agents have been evaluated. Therapeutic optimization should balance the anticipated improvements in quality of life with the potential safety risks.

Angiotensin converting enzyme inhibition enhances collateral artery remodeling in rats with femoral artery occlusion

Evidence from experimental animal studies indicate that ACE inhibition expands collateral blood flow both in ischemic hearts and peripheral limbs. The present study evaluates whether ACE inhibitor induces collateral blood flow expansion and change of angiogenic gene expression profile in collateral arteries during remodeling. Male Sprague-Dawley rats, weighing 350 g were treated with vehicle (control) or quinapril (ACE inhibitor) at either low dose (3.0 mg/kg) or high dose (18 mg/kg) for 1, 3, 7, 14 days (gene expression) or 16 days (blood flow). All rats received bilateral occlusions of the femoral arteries. Collateral blood flow to the hind limb was assessed by 85Sr and 141Ce-labeled microspheres during treadmill running at 15 and 25 m/min speeds. Quinapril reduced plasma ACE activity by 58% and 88% for the low-dose and high-dose groups, respectively (P < 0.001). High-dose quinapril reduced exercising blood pressure (P < 0.05) and increased hind limb conductance. Collateral blood flows to calf muscles were 51 +/- 3.7, 73 +/- 5.0, and 68 +/- 1.9 mL/min per 100 g in control and quinapril low- and high-dose groups, respectively, during high-speed running (P < 0.001). Real-time RT-PCR revealed that ACE inhibition shifted gene expression to a proangiogenic phenotype in the newly developed collateral arteries. Our findings indicate that ACE inhibition could increase collateral-dependent blood flow and collateral vessel remodeling by promoting proangiogenic gene expression in newly developed collateral arteries. Our results support the potential utility of ACE inhibitor as a therapeutic agent in treating peripheral occlusive arterial disease.

Pharmacological interventions for peripheral artery disease

Peripheral arterial disease (PAD) encompasses the vascular diseases caused primarily by atherosclerosis and thromboembolic pathophysiological processes that alter the normal structure and function of the aorta, its visceral arterial branches and the arteries of the upper and lower extremities. PAD is associated with an increased risk for cardiovascular morbidity and mortality. The goals for pharmacological therapy in PAD should focus on reducing cardiovascular risk, improving walking distance and preventing critical limb ischaemia. Exercise training plays a key role in the therapeutic assessment, as well stopping smoking. Antiplatelet therapy (aspirin) should be given to every PAD patient if there are no contraindications. Neither their combination nor anticoagulant therapy has shown additional benefit in PAD patients. Several pharmacological agents have been developed to improve the functional state of the claudicant and to relieve the symptoms. Many studied drugs have shown either no, a small or a potential benefit. With future development of new drugs for PAD, there is an absolute need for very strict well-designed protocols in order to evaluate the claudication distance, the progression of the disease and the reduction in cardiovascular morbidity and mortality. New developments should focus on improvement of endothelial function, vascular repair and enhancement of collateral circulation.

Angiotensin I-converting enzyme inhibitor improves reactive hyperemia in elderly hypertensives with arteriosclerosis obliterans

Endothelial function in elderly hypertensive patients with arteriosclerosis obliterans has not been evaluated. We examined whether antihypertensive drugs improve vasodilatory response to reactive hyperemia of the limbs in elderly hypertensive patients (83 +/- 8 [SD] years) without (n=46, 0.9 < or = ankle-brachial pressure index < or = 1.4) and with (n=24) arteriosclerosis obliterans (ankle-brachial pressure index < 0.2). Patients were randomized for treatment with monotherapy of either temocapril (14 with and 26 without arteriosclerosis obliterans) or amlodipine (10 with and 20 without arteriosclerosis obliterans) for 6 months. Blood flows of the forearms and legs were measured by strain-gauge plethysmography. The vasodilatory response to the release of compression of the forearms and thighs at 200 mmHg or 20 mmHg more than systolic blood pressure for 5 min and to sublingual administration of nitroglycerin (0.3 mg) was assessed. The maximum reactive hyperemic flow in 35 legs with arteriosclerosis obliterans was significantly (p < 0.001) decreased compared to the value in legs in the control hypertensive subjects. Moreover, maximum reactive hyperemic flow in the forearms of patients with arteriosclerosis obliterans was significantly (p = 0.002) decreased compared to that in the control subjects. Blood pressure was similarly decreased by treatment with temocapril or amlodipine. Response to nitroglycerin (0.3 mg) was not changed by either drug. Treatment with temocapril significantly improved maximum reactive hyperemic flow of not only the legs and forearms in control hypertensives but also the legs and forearms in patients with arteriosclerosis obliterans, and attenuated the worsening of activity of daily living in these patients, although treatment with amlodipine did not. These results suggest that the angiotensin-converting enzyme inhibitor temocapril has a beneficial effect on endothelial function in elderly patients with arteriosclerosis obliterans.

Treatment of hypertension in peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) causes considerable morbidity and mortality. Hypertension is a risk factor for PAD. Therefore, treatment for hypertension must be compatible with the symptoms of PAD. Controversy regarding the effects of beta blockade for hypertension in patients with PAD has led many physicians to stop prescribing beta-blockers. Little is known about the effects of other classes of anti-hypertensive drugs in the presence of PAD.

OBJECTIVES

To determine the effects of anti-hypertensive drugs on the: cardiovascular events and death in patients with hypertension and PAD; symptoms of claudication and critical leg ischaemia; progression of PAD, and revascularisation, or amputations.

SEARCH STRATEGY

Trials were sought via the Specialised Register of the Cochrane Peripheral Vascular Diseases Group (last searched July 2003), the Cochrane Central Register of Controlled Trials (CENTRAL) (last searched Issue 2, 2003), and the NHS Database of Abstracts of Reviews of Effectiveness (DARE) (last searched August 2002). There were no language restrictions. Abstracts of cardiology meetings were studied. Reference lists of papers were also examined.

SELECTION CRITERIA

Randomised controlled trials of at least one anti-hypertensive treatment against placebo, or two anti-hypertensive medications against each other, with interventions lasting at least one month. Trials had to include patients with symptomatic PAD. Trials of poor quality and execution were excluded, as were cross-over trials.

DATA COLLECTION AND ANALYSIS

Data were extracted by one reviewer and checked by the other. Eligible studies were excluded when presentation prevented adequate extraction of data, and enquiries to authors did not yield the raw data.

MAIN RESULTS

Two studies were included in the review. In one trial using perindopril in small numbers of patients with PAD, there was a marginal increase in claudication distance (weighted mean difference (WMD) 8.0, 95% confidence interval (CI) -30.66 to 46.66), but no change in ankle brachial pressure index (ABPI), (WMD 0, 95% CI -0.14 to 0.14), and a reduction in walking distance (WMD -46, 95 % CI -169.24 to 77.24). In patients undergoing angioplasty, a second trial suggested that the calcium antagonist verapamil reduced restenosis, although this was not reflected in the maintenance of a high ABPI.

REVIEWER'S CONCLUSIONS

The evidence for various anti-hypertensive drug classes in PAD is poor, so that it is unknown whether significant benefit or risk accrues from their use. In view of this, no definite recommendations on use or avoidance can be made from the available data.

Peripheral vascular disease and hypertension: a forgotten association?

Peripheral vascular disease (PVD) is associated with a high cardiovascular morbidity and mortality. Intermittent claudication is the most common symptomatic manifestation of PVD, but is also an important predictor of cardiovascular death, increasing it by three-fold, and increasing all-cause mortality by two to five-fold. Hypertension is a common and important risk factor for vascular disorders, including PVD. Of hypertensives at presentation, about 2-5% have intermittent claudication, with this prevalence increasing with age. Similarly, 35-55% of patients with PVD at presentation also have hypertension. Patients who suffer from hypertension with PVD have a greatly increased risk of myocardial infarction and stroke. Apart from the epidemiological associations, hypertension contributes to the pathogenesis of atherosclerosis, the basic underlying pathological process underlying PVD. Hypertension, in common with PVD, is associated with abnormalities of haemostasis and lipids, leading to an increased atherothrombotic state. Nevertheless, none of the large antihypertensive treatment trials have adequately addressed whether a reduction in blood pressure causes a decrease in PVD incidence. There is therefore an obvious need for such outcome studies, especially since the two conditions are commonly encountered together.

Structural adaptation to ischemia in skeletal muscle: effects of blockers of the renin-angiotensin system

OBJECTIVE

To investigate the effects of long-term treatment with blockers of the renin-angiotensin system on capillarization and growth of fibers in ischemic hind-limb muscles and in muscles under normal growth conditions.

METHODS

Ischemia was induced by partial ligation of the left common iliac artery.

RESULTS

Ischemia resulted in a significant increase in capillary and fiber density in the soleus muscle, a significant decrease in mean fiber size and a decrease in muscle cross-sectional area after 4 weeks compared with the contralateral nonischemic muscle. Ischemia also significantly decreased the muscle: body weight ratio of the left soleus muscle. We observed no significant effect on total number of capillaries and capillary: fiber ratio, suggesting that ischemia did not result in an increase in capillarization in this muscle. Treatments with subhypotensive and with hypotensive doses of the angiotensin converting enzyme (ACE) inhibitor benazeprilat, the angiotensin (Ang) II AT1 antagonist valsartan, or the Ang II AT2 antagonist PD 123 319 for 4 weeks did not influence any of the above-described changes in the normal and ischemic muscles and treatment effects were also independent of the degree of reduction of blood pressure.

CONCLUSION

Treatments with an ACE inhibitor and with Ang II receptor antagonists in dose ranges that moderately lower blood pressure do not influence vessel density and any of the other structural adaptations after hind-limb ischemia. Administrations of ACE inhibitors and Ang II AT1 antagonists may therefore be adequate and beneficial therapies under ischemic conditions, such as in the treatment of hypertension complicated by intermittent claudication, for which treatment must not increase ischemia.

Angiotensin-converting enzyme inhibition increases exercise tolerance and muscle blood flow in rats with peripheral arterial insufficiency

To determine the effect of angiotensin-converting enzyme (ACE) inhibition on exercise tolerance and muscle blood flow (BF) to ischemic limbs, both femoral arteries of male Sprague-Dawley rats (approximately 325 g) were surgically stenosed. Rats were either active (treadmill run, 20 m/min (a) 15% grade, 5 d/wk for 3 wk) or sedentary (limited to cage activity), and assigned to one of three doses of zabicipril at 0.0 (zero), 0.3 (low), and 3.0 (high) mg.kg-1.d-1 administered via food intake (N = 14-15/group). After 3 weeks, the left carotid and caudal arteries were catheterized under anesthesia for BF measurement later in the day. Muscle BF was determined during exercise at two treadmill speeds (20 and 30 m/min) with 85Sr and 141Ce labeled microspheres to ensure a peak BF. Plasma ACE was inhibited 31%, 65% in the low- and high-dose sedentary rats and 75%, 74% in the low- and high-dose active animals, respectively (P < 0.001). Angiotensin-converting enzyme inhibition improved exercise tolerance by 3 weeks, at a low speed (20 m/min) in the sedentary groups (P < 0.025) and in a dose-dependent manner at a higher speed (25 m/min) in the active groups (P < 0.001). Blood pressures and heart rates during running were not different among groups. However, total hindlimb BF, reduced to approximately 33% of normal by femoral stenosis, was increased by ACE inhibition and chronic activity in a dose-dependent manner (P < 0.025). Blood flows to the plantar flexors were most improved (approximately 20-40%; to 124 mL.min-1 x 100 g-1) in the high-dose groups (P < 0.01). The higher run speed did not increase BF above the low speed. Training adaptation, indicated by an enhanced muscle mitochondrial content (P < 0.001), was similar for low- and high-dose active animals. Our results indicate that ACE inhibition improves BF to ischemic muscles and, together with chronic physical activity, improves exercise tolerance. The results from this study support those advocating ACE inhibition in managing appropriate patients with peripheral arterial insufficiency.

Antihypertensive therapy and adaptive mechanisms in peripheral ischemia

In the present experiments the effect of long-term peripheral ischemia on the capillary of two hind limb skeletal muscles was investigated in spontaneously hypertensive rats. Furthermore, the effect of antihypertensive therapy on changes in capillarity and on the previously observed hyperreactivity of the ischemic vascular bed to vasoconstrictors was investigated in perfused hind limbs of rats after long-term treatment with the angiotensin I converting enzyme inhibitors captopril (0.5 mg/kg.h) or zabiciprilate (0.025 mg/kg.h), the angiotensin II type 1 receptor antagonist losartan (0.625 mg/kg.h), or the calcium antagonist felodipine (0.042 or 0.42 mg/kg.h). Skeletal muscle ischemia in the left hind limb was induced by partial ligation of the left common iliac artery. Long-term (4 weeks) ischemia increased significantly the capillary-to-fiber ratio in the soleus muscle, composed predominantly of type I fibers in spontaneously hypertensive rats, of the ischemic hind limb, whereas capillarity in the contralateral muscle was not affected. Furthermore, capillarity in the gastrocnemius muscle (type II muscle fiber part) of both the ischemic and contralateral hind limb did not change. Long-term treatment with the angiotensin I converting enzyme inhibitors during ischemia abolished the increase in the capillary-to-fiber ratio in the soleus muscle, whereas a comparable antihypertensive dose of felodipine had no effect. Greater blood pressure reductions by both losartan and felodipine prevented increases in capillarization in skeletal muscle ischemia. With respect to vascular hyperreactivity during ischemia, only treatment with losartan normalized reactivity of the ischemic vascular bed to vasoconstrictors.(ABSTRACT TRUNCATED AT 250 WORDS)

A multicenter study of doxazosin in the treatment of patients with mild or moderate essential hypertension and concomitant intermittent claudication

This study assessed the efficacy and safety of once-daily doxazosin in the treatment of patients (n = 19) with mild or moderate essential hypertension (sitting diastolic blood pressure [DBP] 95 to 114 mm Hg) and concomitant intermittent claudication (Doppler ankle/arm ratio of less than 0.80 and walking tolerance of less than 700 m on the treadmill). After 14 weeks of treatment with doxazosin, a significant (p less than 0.05) reduction in systolic blood pressure and DBP was observed. Mean blood pressures were reduced from 170/100 mm Hg at baseline to 161/93 mm Hg at the end of treatment. Minor changes in heart rate occurred, which with continued treatment were not statistically significant from baseline. In 12 of 16 (75.0%) efficacy-evaluable patients blood pressure was normalized (DBP to less than or equal to 90 mm Hg with an greater than or equal to 5 mm Hg reduction from baseline) with a mean daily dose of 7.6 mg/day. Doxazosin improved the hypertension severity category in 13 of 16 (81.3%) patients. The blood pressure ratios between both the thighs and arms and ankles and arms showed no statistically significant changes after treatment with doxazosin. Thigh blood flow at rest and the reactive hyperemia after 3 minutes of arterial occlusion did not change statistically. There was a tendency for pain-free distance to improve. Laboratory data were not significantly changed after treatment with doxazosin. Of the 19 patients studied, 5 reported mild or moderate side effects that were either tolerated or disappeared with continued treatment. No patient had therapy withdrawn and no patient required a dose reduction.(ABSTRACT TRUNCATED AT 250 WORDS)