Constantinos G. Missouris

Renal artery stenosis: A common and important problem in patients with peripheral vascular disease

OBJECTIVE To study the prevalence, severity, vascular risk factors, and clinical implications of renal artery stenosis in patients with peripheral vascular disease. DESIGN Cross-sectional study of consecutive patients who were electively referred from the department of vascular surgery for lower limb digital subtraction angiography. SETTING St. Georges Hospital, London, United Kingdom. SUBJECTS One hundred twenty-seven patients presenting with intermittent claudication or lower limb ischemic ulceration. MAIN OUTCOME MEASURES Prevalence and clinical importance of renal artery stenosis in patients with peripheral vascular disease adjusted for the confounding effects of age and hypertension. RESULTS Of the 127 patients, 57 (44.9%) had renal artery disease, of whom 22 (17.3%) had mild disease, 20 (15.7%) had severe disease, and 15 (11.8%) had bilateral renal artery stenosis. There was a significant positive relationship between the presence of renal artery stenosis and the severity of peripheral vascular disease (p = 0.00015). The risk of having renal artery stenosis was nearly four times greater in those with three to four vessels affected and nearly seven times greater in those with five or more vessels affected as compared with those with a milder degree of peripheral vascular disease (one or two vessels affected). This association persisted when the confounding effect of age and hypertension was accounted for. Six patients (31.6%) with renal artery stenosis who underwent revascularization for peripheral vascular disease died during the early postoperative period of cardiac or renal complications. None of the patients with normal renal arteries who had similar surgery developed postoperative complications (p = 0.005). CONCLUSIONS Renal artery stenosis is a common independent feature in patients with peripheral vascular disease, and its prevalence increases with the increasing severity of the peripheral vascular disease. The postoperative risk following revascularization for peripheral vascular disease appears to be greater in those patients with renal artery stenosis. All patients studied with digital subtraction angiography for peripheral vascular disease should have an aortic flush performed to image the renal arteries. This information may be used to identify those patients likely to develop postoperative complications during peripheral revascularization.

Echocardiography overestimates left ventricular mass : a comparative study with magnetic resonance imaging in patients with hypertension

Objective To compare measurement of left ventricular mass (LVM) by M-mode echocardiography and magnetic resonance imaging (MRI) in hypertensive subjects. Design A prospective study. Subjects Twenty-four untreated hypertensive patients [19 men and five women, aged 51 ± 2 (mean ± SEM) years, supine blood pressure 159/101 ± 3/1 mmHg]. Setting The Blood Pressure Unit, St Georges Hospital Medical School and Magnetic Resonance Unit, Royal Brompton National Heart and Lung Hospital, London. Main outcome measures LVM estimated both by M-mode echocardiography and by MRI. Results Using three standard M-mode formulae, widely different values of LVM were obtained with echocardiography [American Society of Echocardiography (ASE) 319 ± 21 g, Penn 273 ± 19g, Teichholz 191 ± 11 g]. By MRI, the LVM was 232 ± 11 g. The differences between MRI and echocardiography could not be explained in terms of the timing of measurements in the cardiac cycle. When single-slice MRI measurements at the appropriate level were applied to the ASE and Penn formulae, the LVM was again overestimated. Conclusion Our study has shown major differences in LVM estimated using methods based on one-dimensional (echocardiography) compared with three-dimensional (MRI) data. These differences seem to be largely the result of the geometrical assumptions on which M-mode measurements are based. Our findings have important clinical implications for the assessment of the severity and response to treatment of left ventricular hypertrophy in hypertensive patients.

Angiotensin-Converting Enzyme Gene Polymorphism What to Do About All the Confusion?

There is great continuing interest in the link between a deletion variant of the gene for ACE and increased incidence of MI.1 Although some studies2 3 4 5 have failed to confirm this finding, many6 7 8 9 10 have reported an association between the ACE*D allele and CHD, including several recent articles published in Circulation . Other positive associations with the ACE*D allele include restenosis after coronary angioplasty,6 cardiac hypertrophy and remodeling,11 12 13 ischemic or idiopathic dilated cardiomyopathy,14 hypertrophic cardiomyopathy,15 atheromatous renal artery stenosis,16 lacunar stroke,17 and diabetic nephropathy.18 ### Controversy Regarding ACE*D and Ischemic Heart Disease The alu repeat is the most common family of repeats in the human genome. The insertion that gives rise to the ACE*I allele is an alu repeat in intron 16 of the ACE gene.19 The ACE*D allele results from the absence of the above insertion in the ACE gene. There is major disagreement about which individuals with the ACE*D allele are at greater risk of cardiovascular disease. The finding by Cambien et al1 that classically low-risk individuals (low body mass index and low apolipoprotein B) are more likely to develop MI was not confirmed by Ludwig and colleagues8 or Mattu and colleagues.9 Although Mattu et al9 reported an association of the ACE*D allele with CHD in low-risk patients, this association was lost when the data were corrected for body mass index. Ludwig et al8 showed no such correlation but found that the ACE*D allele predicts MI. However, their sample size was only adequate to detect an odds ratio of >3.2 for an association between the ACE*D allele and CAD in low-risk patients.8 In fact, the frequencies of ACE*D in patients with CAD, CAD/MI, and low-risk CAD/MI were 0.53, 0.59, and 0.64, respectively, …

Non-invasive screening for renal artery stenosis with ultrasound contrast enhancement.

Objective Our aim was to evaluate duplex ultrasound imaging in the identification of renal artery stenosis using a new technique to enhance the recorded Doppler signal. Design Colour Doppler studies of interlobar renal arteries were performed before and after enhancement using an intravenous contrast of galactose microparticle suspension containing microbubbles (Levovist, Schering) in patients with angiographically confirmed renal artery stenosis. Setting Blood Pressure Unit, St. Georges Hospital Medical School, and Department of Radiology, The Middlesex Hospital, London, UK. Participants Twenty-one consecutive hypertensive patients in whom the diagnosis of renal artery stenosis was made on digital subtraction angiography. Main outcome measures The diagnosis of haemodynamically significant renal artery stenosis (≥60% on angiography). Results With Levovist, there was a 20 db increase in the Doppler intensity and, as a result, intrarenal signals were much more clearly delineated and distinct spectral waveforms were obtained from all but one kidney, which was occluded. Significant associations were found between the degree of stenosis (as assessed by angiography) and the following Doppler parameters: diastolic velocity (F=7.6; P < 0.01), acceleration time (F=33.5, < 0.0001), peak systolic velocity (F=37.7, P < 0.0001) and acceleration (F=60.0; P < 0.0001). Without enhancement, there were five false-positive and two false-negative examinations (sensitivity 85%; specificity 79%) using the acceleration cut-off value of 3.5 m/s2 to identify haemodynamically significant renal artery stenosis (≥60% on angiography). After contrast enhancement, there were only three false-positive and one false-negative examinations (sensitivity 94% and specificity of 88%) using the acceleration cut-off value of 3.75 m/s2 and the examination time was reduced by approximately half (sensitivity and specificity of 90% using the acceleration cut-off value of 3.5 m/s2). Conclusions Our results suggest that renal duplex scanning using contrast enhancement is a promising new non-invasive technique in screening patients with suspected renal artery stenosis. Contrast enhancement produces more reproducible spectral waveforms, improves accuracy and halves the examination time.

Left ventricular mass in normotensive subjects with autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease increases the risk of premature cardiovascular disease and sudden death.1 One possible mechanism may be left ventricular hypertrophy, which exacerbates cardiac risk in patients with other types of disease. We assessed whether disproportionate cardiac hypertrophy occurs in polycystic kidney disease. Asymptomatic, untreated subjects with normal renal function and no history of hypertension were selected from our polycystic register. Fourteen out of 23 eligible white subjects were recruited (10 women and four men, mean age 32 (SD 12) years (range 16-55), mean supine blood pressure 122/76 mm Hg (range 144-103/86-59)). These were age and sex matched with 14 unrelated, white, healthy volunteers (mean age 33 (SD 13) years (range 18-58), mean blood pressure 116/ 70 mm Hg (range 140-89/86-60)). All subjects had a serum creatinine concentration below 120 μmol/l and a creatinine clearance above 80 ml/min. The study was approved by the hospital ethics committee. Subjects were studied on their usual …

Regression of atherosclerotic renal artery stenosis with aggressive lipid lowering therapy

Lipid lowering therapy has been shown to reduce the rate of progression and even cause the regression of atherosclerotic lesions in coronary, carotid and peripheral arteries. Moreover, recent work has confirmed that such therapy results in improved survival not only in patients with established coronary heart disease, but also in asymptomatic men with mild or moderate hypercholesterolaemia. We describe a case in which agressive lipid lowering therapy with an HMG CoA reductase inhibitor was associated with the regression of an atherosclerotic plaque of the renal artery.

Endovascular Treatment of Renal Artery Stenosis

Significant changes have occurred in the treatment of renal artery disease over the past few years. Although excellent clinical results can be obtained with surgery, percutaneous transluminal renal angioplasty has proved similarly efficacious and is now the treatment of choice for nonostial atherosclerotic stenoses and fibromuscular dysplasia. The introduction of stents has become a valuable adjunctive therapy for postangioplasty restenosis and dissection.

A case of donepezil-related torsades de pointes.

An 80-year-old woman with Alzheimers dementia presented with diarrhoea, vomiting and worsening confusion following an increase in donepezil dose from 5 to 10 mg. The ECG revealed prolongation of QTc interval. Soon after admission, she became unresponsive with polymorphic ventricular tachycardia (VT). Cardiopulmonary resuscitation with a 200 J shock was successful in establishing cardiac output. Following the discontinuation of donepezil, the QTc interval normalised and no further arrhythmias were recorded. Treatment with anticholinesterase inhibitors may result in life-threatening VT. Vigilance is required for the identification of this condition in patients presenting with presyncope, syncope or seizures.

Serotonin and heart rate in hypertensive and normotensive subjects

Plasma and platelet levels of 5-hydroxytryptamine (5 HT) may be altered in essential hypertension. To establish the determinants and correlates of 5 HT in plasma and platelets, we studied 53 untreated subjects with essential hypertension (26 men; 30 whites; mean supine blood pressure 172/101 mm Hg; mean age 49.3 +/- 1.5 years) and 61 normotensive subjects (37 men; 47 whites; mean supine blood pressure 128/78 mm Hg; mean age 42.8 +/- 1.6 years). Plasma and platelet 5 HT were assayed by reverse-phase high performance liquid chromatography with electrochemical detection. No significant difference was found in platelet-poor plasma or platelet 5 HT levels in hypertensive or normotensive subjects (plasma: 43.0 +/- 4.2 and 39.6 +/- 4.4 nmol/L; platelet: 1.65 +/- 1.22 and 1.70 +/- 1.39 nmol/10(9) cells in hypertensive and normotensive subjects, respectively). No significant correlation was found between plasma or platelet 5 HT and systolic or diastolic blood pressure (plasma: r = 0.01 and 0.01 in normotensive subjects and r = 0.01 and -0.14 in hypertensive subjects; platelet: r = 0.12 and 0.13 in normotensive subjects and r = 0.02 and -0.09 in hypertensive subjects). However, plasma 5 HT was associated with supine and standing pulse rates (supine: r = 0.27, p = 0.05 in normotensive subjects and r = 0.54, p < 0.001 in hypertensive subjects; standing: r = 0.19 and r = 0.46, p < 0.001, respectively). Significant relations were also found between platelet 5 HT levels and supine and standing heart rate in the subjects mentioned above (supine: r = 0.28, p = 0.05 in normotensive subjects and r = 0.64, p < 0.001 in hypertensive subjects; standing: r = 0.24 and r = 0.51, p < 0.001, respectively). These associations were stronger in the hypertensive group as a whole, and they held when adjustment was made for differences in age and total blood cholesterol. The present study showed that plasma and platelet 5 HT are not significantly altered in hypertensive subjects. However, plasma and platelet 5 HT levels showed a significant association with supine and standing pulse rate predominantly in hypertensive subjects. This is consistent with experimental evidence of a positive chronotropic effect of 5 HT on perfused hearts and it suggests a possible role of plasma serotonin in the regulation of heart rate.

Predictors of mortality in patients with peripheral vascular disease. A prospective follow-up study

Background P eripheral vascular disease is associated with increased cardiovascular mortality and reduced life expectancy. The main causes of death are due to concomitant coronary heart and cerebrovascular disease. Objective To assess the long-term survival of patients with PVD and to investigate the impact of the presence of risk factors on mortality. Design Cohort study of patients with intermittent claudication and angiographically established PVD. Baseline investigations were performed in 1990‐2; follow-up continued until 1999.