Validity, reliability and feasibility of a new observation rating tool and a post encounter rating tool for the assessment of clinical reasoning skills of medical students during their internal medicine clerkship: a pilot study

BACKGROUND

Systematic assessment of clinical reasoning skills of medical students in clinical practice is very difficult. This is partly caused by the lack of understanding of the fundamental mechanisms underlying the process of clinical reasoning.

METHODS

We previously developed an observation tool to assess the clinical reasoning skills of medical students during clinical practice. This observation tool consists of an 11-item observation rating form (ORT). In the present study we verified the validity, reliability and feasibility of this tool and of an already existing post-encounter rating tool (PERT) in clinical practice among medical students during the internal medicine clerkship.

RESULTS

Six raters each assessed the same 15 student-patient encounters. The internal consistency (Cronbach's alfa) for the (ORT) was 0.87 (0.71-0.84) and the 5-item (PERT) was 0.81 (0.71-0.87). The intraclass-correlation coefficient for single measurements was poor for both the ORT; 0.32 (p < 0.001) as well as the PERT; 0.36 (p < 0.001). The Generalizability study (G-study) and decision study (D-study) showed that 6 raters are required to achieve a G-coefficient of > 0.7 for the ORT and 7 raters for the PERT. The largest sources of variance are the interaction between raters and students. There was a consistent correlation between the ORT and PERT of 0.53 (p = 0.04).

CONCLUSIONS

The ORT and PERT are both feasible, valid and reliable instruments to assess students' clinical reasoning skills in clinical practice.

Observable phenomena that reveal medical students' clinical reasoning ability during expert assessment of their history taking: a qualitative study

BACKGROUND

During their clerkships, medical students are meant to expand their clinical reasoning skills during their patient encounters. Observation of these encounters could reveal important information on the students' clinical reasoning abilities, especially during history taking.

METHODS

A grounded theory approach was used to analyze what expert physicians apply as indicators in their assessment of medical students' diagnostic reasoning abilities during history taking. Twelve randomly selected clinical encounter recordings of students at the end of the internal medicine clerkships were observed by six expert assessors, who were prompted to formulate their assessment criteria in a think-aloud procedure. These formulations were then analyzed to identify the common denominators and leading principles.

RESULTS

The main indicators of clinical reasoning ability were abstracted from students' observable acts during history taking in the encounter. These were: taking control, recognizing and responding to relevant information, specifying symptoms, asking specific questions that point to pathophysiological thinking, placing questions in a logical order, checking agreement with patients, summarizing and body language. In addition, patients' acts and the course, result and efficiency of the conversation were identified as indicators of clinical reasoning, whereas context, using self as a reference, and emotion/feelings were identified by the clinicians as variables in their assessment of clinical reasoning.

CONCLUSIONS

In observing and assessing clinical reasoning during history taking by medical students, general and specific phenomena to be used as indicators for this process could be identified. These phenomena can be traced back to theories on the development and the process of clinical reasoning.

The impact of the implementation of physician assistants in inpatient care: A multicenter matched-controlled study

BACKGROUND

Medical care for admitted patients in hospitals is increasingly reallocated to physician assistants (PAs). There is limited evidence about the consequences for the quality and safety of care. This study aimed to determine the effects of substitution of inpatient care from medical doctors (MDs) to PAs on patients' length of stay (LOS), quality and safety of care, and patient experiences with the provided care.

METHODS

In a multicenter matched-controlled study, the traditional model in which only MDs are employed for inpatient care (MD model) was compared with a mixed model in which besides MDs also PAs are employed (PA/MD model). Thirty-four wards were recruited across the Netherlands. Patients were followed from admission till one month after discharge. Primary outcome measure was patients' LOS. Secondary outcomes concerned eleven indicators for quality and safety of inpatient care and patients' experiences with the provided care.

RESULTS

Data on 2,307 patients from 34 hospital wards was available. The involvement of PAs was not significantly associated with LOS (β 1.20, 95%CI 0.99-1.40, p = .062). None of the indicators for quality and safety of care were different between study arms. However, the involvement of PAs was associated with better experiences of patients (β 0.49, 95% CI 0.22-0.76, p = .001).

CONCLUSIONS

This study did not find differences regarding LOS and quality of care between wards on which PAs, in collaboration with MDs, provided medical care for the admitted patients, and wards on which only MDs provided medical care. Employing PAs seems to be safe and seems to lead to better patient experiences.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01835444.

[Assessment of physicians with a foreign diploma; results of 10 years of testing of physicians with a foreign diploma]

OBJECTIVE

To determine the result of the assessment procedure, initiated on 1 December 2005, for physicians with a foreign diploma who wish to practice in the Netherlands.

DESIGN

Retrospective, descriptive study.

METHOD

The Commission for Foreign Healthcare Graduates (CBGV) collected data on physicians with a foreign diploma who followed the procedure for requesting a declaration of professional competence and admission to the Dutch Individual Healthcare Professions (BIG) register between December 2005 - December 2015. The procedure comprises a language and communication test, followed by tests of professional competence. On the grounds of the test results, the CBGV can decide if a physician should follow a specific training course. The number of physicians who ultimately obtained BIG registration was determined.

RESULTS

During the study period, 183 of the 206 physicians with a foreign diploma passed the general knowledge and skills tests. A total of 176 of the 183 physicians took the professional competence tests. In 43 (25%) of them no shortcomings in knowledge and skills were seen. They were registered in the BIG register for a period of supervision. In 129 (73%), shortfalls were made up by means of focused training programme. In 4 (2%) of them no training was possible. On the date of assessment, 137 (78%) physicians were registered. This number is expected to rise to 151 (86%).

CONCLUSION

The provision of a further course of training that is focused on the elimination of identified shortcomings in physicians with a foreign diploma, increases the percentage of foreign physicians that are successfully admitted to the BIG register.

The Use of the Ambulatory Arterial Stiffness Index in Patients Suspected of Secondary Hypertension

The ambulatory arterial stiffness index (AASI) is a marker of arterial stiffness and is derived from ambulatory 24-h blood pressure registration. We studied whether the AASI could be used as a predictive factor for the presence of renal artery stenosis (RAS) in patients with a suspicion of secondary hypertension and as such as a diagnostic tool for RAS. We included 169 patients with difficult-to-treat hypertension. They all underwent 24-h ambulatory blood pressure monitoring registration, imaging of the renal arteries, and cardiovascular risk measurement, including smoking, history, biometrics, blood pressure, renal function, lipids, and glucose metabolism. Performing univariate and multivariate analyses, we investigated if AASI and the other cardiovascular risk factors were related to the presence of RAS. Of the 169 patients (49% women), 31% had RAS. The mean AASI was 0.44 (0.16). The presence of RAS showed no significant correlation with AASI (r = 0.14, P = 0.06). Age (r = 0.19, P = 0.01), hypercholesterolemia (r = 0.26, P = 0.001), history of CVD (r = 0.22, P = 0.004), and creatinine clearance (r = -0.34, P < 0.001) all demonstrated a correlation with RAS. Although AASI is higher in patients with RAS, AASI does not independently predict the presence of RAS in hypertensive subjects.

[Hypertension due to fibromuscular dysplasia: look for additional disease sites]

Fibromuscular dysplasia (FMD) is a non-inflammatory, non-atherosclerotic vasculopathy that can lead to arterial stenosis, occlusion, aneurysms, and dissection. FMD of the renal arteries can lead to renovascular hypertension. Percutaneous angioplasty of the renal arteries (PTRA) can lead to normalization of blood pressure in 45% of patients with renal artery stenosis caused by FMD, particularly in younger patients and patients with a short history of hypertension. A considerable number of the patients with renovascular FMD also have cervical FMD, which can lead to ischaemic or haemorrhagic stroke. In this article we discuss diagnostic and therapeutic options, illustrated by two cases of patients with renovascular and carotid FMD. Most of the recommendations are based on data from retrospective studies and expert opinion; prospective studies on the optimal diagnostic strategy and treatment are therefore, urgently required.

Analysis of the level of general clinical skills of physician assistant students using an objective structured clinical examination

RATIONALE, AIMS AND OBJECTIVES

The physician assistant (PA) is trained to perform clinical tasks traditionally performed by medical doctors (MDs). Previous research showed no difference in the level of clinical skills of PAs compared with MDs in a specific niche, that is the specialty in which they are employed. However, MDs as well as PAs working within a specialty have to be able to recognize medical problems in the full scope of medicine. The objective is to examine PA students' level of general clinical skills across the breadth of clinical cases.

METHOD

A cross-sectional study was conducted. PA students and recently graduated MDs in the Netherlands were observed on their clinical skills by means of an objective structured clinical examination comprising five stations with common medical cases. The level of mastering history taking, physical examination, communication and clinical reasoning of PA students and MDs were described in means and standard deviation. Cohen's d was used to present effect sizes.

RESULTS

PA students and MDs score about equal on history taking (PA 5.8 ± 0.8 vs. MD 5.7 ± 0.7), physical examination (PA 4.8 ± 1.3 vs. MD 5.4 ± 0.8) and communication (PA: 8.2 ± 0.8 vs. MD: 8.6 ± 0.5) in the full scope of medicine. In the quality of the report, including the patient management plan, PA students scored a mean of 6.0 ± 0.6 and MDs 6.8 ± 0.6.

CONCLUSIONS

In this setting in the Netherlands, PA students and MDs score about equal in the appraisal of common cases in medical practice. The slightly lower scores of PA students' clinical reasoning in the full scope of clinical care may have raise attention to medical teams working with PAs and PA training programmes.

Reliability and validity of an extended clinical examination

INTRODUCTION

An extended clinical examination (ECE) was administered to 85 final year medical students at the Radboud University Medical Centre in the Netherlands. The aim of the study was to determine the psychometric quality and the suitability of the ECE as a measurement tool to assess the clinical proficiency of eight separate clinical skills.

METHODS

Generalizability studies were conducted to determine the generalizability coefficient and the sources of variance of the ECE. An additional D-study was performed to estimate the generalizability coefficients with altering numbers of stations.

RESULTS

The largest sources of variance were found in skill difficulties (36.18%), the general error term (26.76%) and in the rank ordering of skill difficulties across the stations (21.89%). The generalizability coefficient of the entire ECE was above the 0.70 lower bound (G = 0.74). D studies showed that the separate skills could yield sufficient G coefficients in seven out of eight skills, if the ECE was lengthened from 8 to 14 stations.

DISCUSSION

The ECE proved to be a reliable clinical assessment that enables examinees to compose a clinical reasoning path through self-obtained data. The ECE can also be used as an assessment tool for separate clinical skills.

Student performance of the general physical examination in internal medicine: an observational study

BACKGROUND

Many practicing physicians lack skills in physical examination. It is not known whether physical examination skills already show deficiencies after an early phase of clinical training. At the end of the internal medicine clerkship students are expected to be able to perform a general physical examination in every new patient encounter. In a previous study, the basic physical examination items that should standardly be performed were set by consensus. The aim of the current observational study was to assess whether medical students were able to correctly perform a general physical examination regarding completeness as well as technique at the end of the clerkship internal medicine.

METHODS

One hundred students who had just finished their clerkship internal medicine were asked to perform a general physical examination on a standardized patient as they had learned during the clerkship. They were recorded on camera. Frequency of performance of each component of the physical examination was counted. Adequacy of performance was determined as either correct or incorrect or not assessable using a checklist of short descriptions of each physical examination component. A reliability analysis was performed by calculation of the intra class correlation coefficient for total scores of five physical examinations rated by three trained physicians and for their agreement on performance of all items.

RESULTS

Approximately 40% of the agreed standard physical examination items were not performed by the students. Students put the most emphasis on examination of general parameters, heart, lungs and abdomen. Many components of the physical examination were not performed as was taught during precourses. Intra-class correlation was high for total scores of the physical examinations 0.91 (p <0.001) and for agreement on performance of the five physical examinations (0.79-0.92 p <0.001).

CONCLUSIONS

In conclusion, performance of the general physical examination was already below expectation at the end of the internal medicine clerkship. Possible causes and suggestions for improvement are discussed.

A core physical examination in internal medicine: what should students do and how about their supervisors?

BACKGROUND

Performance of a focused physical examination will induce a high cognitive load for medical students in the early phase of the clinical clerkships.

AIM

To come to a workable and clinically applicable standard physical examination for medical students to be used in every new patient in the daily clinical practice of internal medicine.

METHOD

A questionnaire held among physicians that supervise students during the clerkship of internal medicine in one Dutch training region.

RESULTS

Of the complete list of physical examination 55 items were considered to be an integral part of the standard general physical examination for medical students. Most emphasized were elements of the physical examination aimed at general parameters, thorax and abdomen, vascular status, lymph nodes, spinal column, skin and some parts of the neurological examination. The standard physical examinations performed by supervisors themselves contain fewer items than they expected from the students. The expectations a supervisor has towards the student correlates with the frequency with which they apply the various components in their own physical examination.

CONCLUSION

This study provides us with a 'core' physical examination for medical students that can be applied in the early phase of the clinical clerkships.

[Renal artery stenosis: do not toss the stent aside]

Primary stent placement for atherosclerotic renal artery stenosis (ARAS) has become a subject of considerable debate. It even seems that the indication has been cast aside altogether, maybe as a result of prospective trials seeking to define the role of renal revascularisation, which failed to establish a compelling benefit for endovascular stenting when added to effective medical regimens. Various explanations for these disappointing results have been offered. However, it could be that the currently accepted belief, i.e. that only stenoses greater than 50-70% of the luminal surface result in ischaemic changes leading to hypertension and renal insufficiency, needs rethinking. There is ample experimental evidence that ischaemia per se does not fully explain the clinical sequelae accompanying ARAS. Treatment of advanced stenosis and renal derangement might be unsuccessful because the changes resulting from these conditions are already irreversible. Perhaps treatment should be initiated earlier in the disease process when stenosis and renal impairment are less advanced.

[Task shifting and quality of care in practice; physician assistants compared with anaesthesiology residents in the preoperative anaesthesiology outpatient clinic]

OBJECTIVE

To compare the clinical competencies of second-year anaesthesiology residents and physician assistants (PA) in the preoperative anaesthesiology outpatient clinic.

DESIGN

Comparative qualitative observational study.

METHOD

The two study groups were compared using 5 test stations representing 5 different cases of varying degrees of complexity with standardized patients. For each case, the patients and two anaesthesiologists assessed the results of the PAs and the residents using a quantitative scoring system for 4 clinical skills relevant to the preoperative anaesthesiology outpatient clinic. These skills were history-taking, physical examination, communication, and reporting. At each station, a score was calculated for each skill. The groups' scores were subsequently compared.

RESULTS

9 PAs and 11 residents carried out the station tests. There were no significant differences between the two groups of participants.

CONCLUSION

In this study in a preoperative anaesthesiology outpatient clinic no difference in clinical competencies was found between PAs and second-year anaesthesiology residents.

The prevalence of renal artery stenosis among patients with diabetes mellitus

BACKGROUND

Patients with diabetes mellitus (DM) have a high prevalence of atherosclerotic vascular lesions. It is therefore reasonable to assume that also the rate of renal artery stenosis (RAS) is higher. The presence of a RAS can have implications for the treatment of patients with diabetes mellitus and hypertension and renal impairment. Therefore it is important to be informed about the chance that a RAS is present among such patients.

METHODS

We prospectively studied the prevalence of atherosclerotic renal artery stenosis (RAS) among patients with diabetes mellitus. Patients were included if they were diagnosed with DM and hypertension with or without impairment of renal function. If causes of renal disease other than DM or hypertension were more probable on the basis of biochemical data, then such patients were excluded. A magnetic resonance angiography (MRA) of the renal arteries was made in 54 included successive patients.

PATIENT CHARACTERISTICS

mean age 59 ± 8.5 years (range 35 to 80). Eight patients had DM 1 and 46 DM 2. Mean BMI was 31.4 ± 5.6 kg/m(2). A RAS was present in 18 of the 54 (33%) patients, 3 patients had bilateral stenoses. Factors related to the presence of RAS were diastolic blood pressure, glomerular filtration rate and dyslipidaemia.

CONCLUSION

In this group of diabetic patients with hypertension and or renal impairment the prevalence of RAS was 33%.

['You may go ahead and get undressed now']

For an experienced physician, it is common practice that the patient undresses for a physical examination. Medical students and young doctors can be more restrained. Unfamiliarity, feelings of shame and fear of being accused of sexual intimidation can prevent them from having the patient undress. This can lead to an incomplete performance of the physical examination by young doctors, and to missed diagnoses. This article's aim is to offer educators guidance to help young doctors in dealing with this subject.

Checking the checklist: a content analysis of expert- and evidence-based case-specific checklist items

OBJECTIVES

Research on objective structured clinical examinations (OSCEs) is extensive. However, relatively little has been written on the development of case-specific checklists on history taking and physical examination. Background information on the development of these checklists is a key element of the assessment of their content validity. Usually, expert panels are involved in the development of checklists. The objective of this study is to compare expert-based items on OSCE checklists with evidence-based items identified in the literature.

METHODS

Evidence-based items covering both history taking and physical examination for specific clinical problems and diseases were identified in the literature. Items on nine expert-based checklists for OSCE examination stations were evaluated by comparing them with items identified in the literature. The data were grouped into three categories: (i) expert-based items; (ii) evidence-based items, and (iii) evidence-based items with a specific measure of their relevance.

RESULTS

Out of 227 expert-based items, 58 (26%) were not found in the literature. Of 388 evidence-based items found in the literature, 219 (56%) were not included in the expert-based checklists. Of these 219 items, 82 (37%) had a specific measure of importance, such as an odds ratio for a diagnosis, making that diagnosis more or less probable.

CONCLUSIONS

Expert-based, case-specific checklist items developed for OSCE stations do not coincide with evidence-based items identified in the literature. Further research is needed to ascertain what this inconsistency means for test validity.

Clinical significance of low-grade renal artery stenosis

BACKGROUND

Patients with a renal artery stenosis (RAS) >50% carry an increased risk for future cardiovascular (CV) events. Experimental literature on this topic suggests that this might as well be true for subjects with lower-grade RAS.

METHODS

Recruitment in this longitudinal cohort study was conducted from 1982 to 2002 in a Dutch University Hospital. Included in this study were 301 hypertensive patients clinically suspected of having RAS. Study participants were radiologically classified as having no, a low-grade (<50% lumen narrowing) or high-grade (> or =50%) RAS. A predetermined composite CV end-point was defined as one of the following: myocardial infarction or 'objectified' angina pectoris, ischaemic stroke or death from any CV cause. Other end-points were the occurrence of CV complications, all-cause plus CV mortality and decline in renal function.

RESULTS

During a median follow-up of 8.2 years, the incidence of the composite end-point totalled 79 events. After full adjustment in Cox models, a significant risk increase in high-grade [hazard ratio (HR) 2.81; P = 0.002] and low-grade RAS (HR 2.32; P = 0.038) was observed. Other end-points did not differ significantly between study groups.

CONCLUSION

Hypertensive subjects with RAS of any extent, compared with hypertensives without RAS, carry a substantially increased risk for future CV events. Therefore, even in patients with low-grade RAS, aggressive pharmacological treatment strategies should be adopted as a preventive measure.

The clinical skills assessment for international medical graduates in The Netherlands

AIM

A need was felt to improve the quality of admission and licensing procedures for international medical graduates in The Netherlands.

METHOD

A clinical skills assessment was designed as part of a new procedure to realize a high-stakes, fair, transparent, and a time-limited path of admission for international medical graduates to the Dutch health care system. Additionally, it should provide a well-founded advice about length and content of additional medical training, should this be indicated by the outcome of the assessment.

RESULTS

The clinical skills assessment procedure was developed as a Dutch variant of the "Step 2 Clinical Skills examination" of the Educational Commission for Foreign Medical Graduates (ECFMG) in collaboration with the United States National Board of Medical Examiners, which has a well-documented validity and reliability. The experience with the new procedure is yet limited, but enough to warrant a report.

DISCUSSION

Worldwide, a number of countries have developed such high-stake assessment procedures, but they show little uniformity and transparency. By describing the design and development of our procedure, we do not pretend to set a standard, but we hope to contribute to more fair, accurate and uniform approaches for doctors moving from one country to another.

Stent placement in patients with atherosclerotic renal artery stenosis and impaired renal function: a randomized trial

BACKGROUND

Little is known about the efficacy and safety of renal artery stenting in patients with atherosclerotic renal artery stenosis (ARAS) and impaired renal function.

OBJECTIVE

To determine the efficacy and safety of stent placement in patients with ARAS and impaired renal function.

DESIGN

Randomized clinical trial. Randomization was centralized and computer generated, and allocation was assigned by e-mail. Patients, providers, and persons who assessed outcomes were not blinded to treatment assignment.

SETTING

10 European medical centers.

PARTICIPANTS

140 patients with creatinine clearance less than 80 mL/min per 1.73 m(2) and ARAS of 50% or greater.

INTERVENTION

Stent placement and medical treatment (64 patients) or medical treatment only (76 patients). Medical treatment consisted of antihypertensive treatment, a statin, and aspirin.

MEASUREMENTS

The primary end point was a 20% or greater decrease in creatinine clearance. Secondary end points included safety and cardiovascular morbidity and mortality.

RESULTS

Forty-six of 64 patients assigned to stent placement had the procedure. Ten of the 64 patients (16%) in the stent placement group and 16 patients (22%) in the medication group reached the primary end point (hazard ratio, 0.73 [95% CI, 0.33 to 1.61]). Serious complications occurred in the stent group, including 2 procedure-related deaths (3%), 1 late death secondary to an infected hematoma, and 1 patient who required dialysis secondary to cholesterol embolism. The groups did not differ for other secondary end points.

LIMITATION

Many patients were falsely identified as having renal artery stenosis greater than 50% by noninvasive imaging and did not ultimately require stenting.

CONCLUSION

Stent placement with medical treatment had no clear effect on progression of impaired renal function but led to a small number of significant procedure-related complications. The study findings favor a conservative approach to patients with ARAS, focused on cardiovascular risk factor management and avoiding stenting.

Validation of a prediction rule for renal artery stenosis

OBJECTIVES

We previously developed a prediction rule to estimate the probability of renal artery stenosis. This rule should be validated before it can be used reliably to select hypertensive patients for renal angiography. We determined the validity of the prediction rule in recent patients and in other settings.

DESIGN

We studied three aspects of validity (agreement between predicted and observed probability of stenosis, discriminative ability, and clinical usefulness) in 180 consecutive patients with drug-resistant hypertension and normal or mildly impaired renal function, who visited six hypertension clinics of academic and community hospitals in the Netherlands. Thirty-five patients (19%) had a significant stenosis.

RESULTS

The clinical characteristics in the rule (age, sex, vascular disease, recent onset of hypertension, smoking, body mass index, abdominal bruit, serum creatinine concentration, and hypercholesterolemia) had similar predictive value in the validation sample and development sample. The predicted probabilities of stenosis agreed well with the observed frequencies (Hosmer-Lemeshow goodness-of-fit test, P = 0.87). The prediction rule discriminated reasonably between patients with and without stenosis in the validation sample with an area under the receiver operating characteristic curve of 0.71. If only patients with predicted probabilities of stenosis of 5% or more were referred for renal angiography, the number of referrals was reduced by 20%, while 9% of patients with a stenosis were missed.

CONCLUSIONS

The prediction rule was valid in more recently treated patients in other settings. If used conservatively, the rule can reliably exclude a small proportion of patients from angiography.

Mechanisms of adenosine-induced renal vasodilatation in hypertensive patients

BACKGROUND

Adenosine is an endogenous nucleoside with potent vasodilatory capacities, released under ischaemic conditions in particular. Its mechanisms of action, however, remain elusive.

OBJECTIVE

To evaluate the role of adenosine, using a non-selective purinergic receptor antagonist, and the possible involvement of nitric oxide in this mechanism. In addition, the production of renin and catecholamines was studied during infusion of adenosine, caffeine, or both.

METHODS

Thirty-three hypertensive patients who underwent diagnostic renal angiography received intrarenal infusions of adenosine either alone or in combination with caffeine or the nitric oxide synthase inhibitor, N-monomethyl-L-arginine (L-NMMA). The effects on renal blood flow (RBF) were assessed by the xenon-133 washout technique and both arterial and renal venous blood samples were taken for measurement of renin and catecholamine concentrations. Intra-arterial blood pressure and heart rate were monitored continuously.

RESULTS

Adenosine induced a dose-dependent vasodilatation. Caffeine alone did not change RBF, but shifted the dose-response curve of adenosine to the right during concomitant infusion of caffeine. RBF during combined infusion of L-NMMA and adenosine was not different from that during adenosine alone, but the decrease in renal vascular resistance was less pronounced during this combination. Renin secretion did not change during the infusion of either adenosine alone or adenosine in combination with caffeine. Catecholamine concentrations also did not change during any of the experiments.

CONCLUSIONS

Adenosine induces vasodilatation in the human hypertensive kidney and this effect is mediated by the adenosine receptor. Nitric oxide plays, at most, a minor part in the adenosine-induced vasodilatation. Furthermore, renin secretion is not affected by adenosine and caffeine.

The effect of arginine vasopressin on endothelin production in the human forearm vascular bed

OBJECTIVES

To study whether arginine vasopressin (AVP) can stimulate endothelin production and/or release in vivo, in the human forearm vasculature.

DESIGN

The effect of the infusion of AVP into the brachial artery on endothelin production across the human forearm vascular bed was studied in healthy male volunteers, and was compared with intra-arterial infusion of placebo. In another group the effects of AVP on endothelin production were studied after a prior infusion of L-NG-monomethyl-arginine (L-NMMA), a nitric oxide-synthase inhibitor. In a fourth group the effect of L-NMMA alone, without AVP infusion, on endothelin production was studied.

METHODS

We measured the effects of AVP, placebo, L-NMMA followed by AVP and L-NMMA followed by placebo on arterial and venous endothelin concentrations in the forearm of four groups, each consisting of five healthy male volunteers. Forearm blood flow was measured by strain gauge plethysmography. The endothelin production was calculated as forearm blood flow times (venous - arterial) endothelin concentration.

RESULTS

The group infused with L-NMMA followed by infusion of 8 ng AVP/min per dl forearm volume showed a significant rise in endothelin production from 1.3 (1.8) to 5.0 (2.0) pg/min/dl at 15 minutes (p<0.05, ANOVA). This rise in endothelin production was also significantly different from the endothelin production at 15 minutes in the other three groups (p<0.01, ANOVA).

CONCLUSION

In healthy male volunteers intra-arterial infusion of AVP induced a rise in endothelin production in the forearm within 15 minutes, but only after prior infusion of L-NMMA. This observation suggests that the AVP-induced production of nitric oxide offsets AVP-mediated release of endothelin.

Accuracy of computed tomographic angiography and magnetic resonance angiography for diagnosing renal artery stenosis

BACKGROUND

Timely, accurate detection of renal artery stenosis is important because this disorder may be a potentially curable cause of hypertension and renal impairment.

OBJECTIVE

To determine the validity of computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) compared with digital subtraction angiography (DSA) for detection of renal artery stenosis.

DESIGN

Prospective multicenter comparative study conducted from 1998 to 2001. Two panels of 3 observers judged CTA and MRA image data and were blinded to all other results. Digital subtraction angiography images were evaluated by consensus.

SETTING

3 large teaching hospitals and 3 university hospitals in the Netherlands.

PATIENTS

402 hypertensive patients with suspected renal artery stenosis were included. A group of 356 patients who underwent all 3 diagnostic tests was used for analysis.

MEASUREMENTS

Reproducibility was assessed by calculating interobserver agreement. Diagnostic performance was evaluated in terms of sensitivity, specificity, and other diagnostic variables. Atherosclerotic stenoses of 50% or greater and fibromuscular dysplasia were considered clinically relevant.

RESULTS

Twenty percent of patients who underwent all 3 tests had clinically relevant renal artery stenosis. Moderate interobserver agreement was found, with kappa values ranging from 0.59 to 0.64 for CTA and 0.40 to 0.51 for MRA. The combined sensitivity and specificity were 64% (95% CI, 55% to 73%) and 92% (CI, 90% to 95%) for CTA and 62% (CI, 54% to 71%) and 84% (CI, 81% to 87%) for MRA.

LIMITATIONS

Eighteen percent of the patients were included nonconsecutively. Digital subtraction angiography may be an imperfect reference test.

CONCLUSION

Computed tomographic angiography and MRA are not reproducible or sensitive enough to rule out renal artery stenosis in hypertensive patients. Therefore, DSA remains the diagnostic method of choice. *For a list of the other investigators and research coordinators who participated in RADISH, see the Appendix.

The structure of medical competence and results of an OSCE

BACKGROUND

Medical competence is a central concept in medical education. Educational efforts in medical training are directed at the achievement of a maximal medical competence. The concept of the structure of medical competence (multidimensional or one-dimensional with strongly interrelated competences) therefore affects the educational developments and assessment procedures.

PURPOSE

To examine the applicability of a one or more dimensional character of medical competence in student assessments, by analysing the results of 356 students in the history taking station of an objective structured clinical examination (OSCE), in relation to other assessment procedures.

METHODS

The performances of 356 students in a history taking station of an OSCE were analysed. Analyses of the checklist scores were aimed at the dimensionality of history taking skills. External criteria were used to test the validity of the scores on the checklist.

RESULTS

The analyses of the scores on the history taking checklist indicated at least five dimensions of history taking skills: the frequency of patient-centred skills, the quality of performance of patient-centred skills, complaint-oriented skills, general social skills, and the provision of procedural information.

CONCLUSION

Medical competence, as a subject of assessment, can be seen as a multifaceted construct. This study shows that history taking alone might be composed of five different dimensions, suggesting that medical competence in respect of assessment might be viewed as a multifaceted construct which in that sense has implications for the assessment of medical competence.

The benefit of STent placement and blood pressure and lipid-lowering for the prevention of progression of renal dysfunction caused by Atherosclerotic ostial stenosis of the Renal artery. The STAR-study: rationale and study design

BACKGROUND

Atherosclerotic renal artery stenosis (ARAS) is associated with progressive loss of renal function and is one of the most important causes of renal failure in the elderly. Current treatment includes restoration of the renal arterial lumen by endovascular stent placement. However, this treatment only affects damage caused by ARAS due to the stenosis and ensuing post-stenotic ischemia. ARAS patients have severe general vascular disease. Atherosclerosis and hypertension can also damage the kidney parenchyma causing renal failure. Medical treatment focuses on the latter. Lipid-lowering drugs (statins) could reduce renal failure progression and could reduce the overall high cardiovascular risk. The additional effect on preserving renal function of stent placement as compared to medical therapy alone is unknown. Therefore, the STAR-study aims to compare the effects of renal artery stent placement together with medication vs. medication alone on renal function in ARAS patients.

METHOD

Patients with an ARAS of > or = 50% and renal failure (creatinine (Cr) clearance < 80 mL/min/1.73 m2) are randomly assigned to stent placement with medication or to medication alone. Medication consists of statins, anti-hypertensive drugs and antiplatelet therapy. Patients are followed for 2 yrs with extended follow-up to 5 yrs. The primary outcome of this study is a reduction in Cr clearance > 20% compared to baseline. This trial will include 140 patients.

Resistance to antihypertensive medication as predictor of renal artery stenosis: comparison of two drug regimens

BACKGROUND

Renal artery stenosis is among the most common curable causes of hypertension. The definitive diagnosis is made by renal angiography, an invasive and costly procedure. The prevalence of renal artery stenosis is less than 1% in non-selected hypertensive patients but is higher when hypertension is resistant to drugs.

OBJECTIVE

To study the usefulness of standardised two-drug regimens for identifying drug-resistant hypertension as a predictor of renal artery stenosis.

DESIGN AND SETTING

Prospective cohort study carried out in 26 hospitals in The Netherlands.

PATIENTS

Patients had been referred for analysis of possible secondary hypertension or because hypertension was difficult to treat. Patients < or =40 years of age were assigned to either amlodipine 10 mg or enalapril 20 mg, and patients >40 years to either amlodipine 10 mg combined with atenolol 50 mg or to enalapril 20 mg combined with hydrochlorothiazide 25 mg. Renal angiography was performed: (1) if hypertension was drug-resistant, ie if diastolic pressure remained > or =95 mm Hg at three visits 1-3 weeks apart or an extra drug was required, and/or (2) if serum creatinine rose by > or =20 micromol/L (> or =0.23 mg/dL) during ACE inhibitor treatment.

RESULTS

Of the 1106 patients with complete follow-up, 1022 had been assigned to either the amlodipine- or enalapril-based regimens, 772 by randomisation. Drug-resistant hypertension, as defined above, was identified in 41% of the patients, and 20% of these had renal artery stenosis. Renal function impairment was observed in 8% of the patients on ACE inhibitor, and this was associated with a 46% prevalence of renal artery stenosis. In the randomised patients, the prevalence of renal artery stenosis did not differ between the amlodipine- and enalapril-based regimens.

CONCLUSIONS

In the diagnostic work-up for renovascular hypertension the use of standardised medication regimens of maximally two drugs, to identify patients with drug-resistant hypertension, is a rational first step to increase the a priori chance of renal artery stenosis. Amlodipine- or enalapril-based regimens are equally effective for this purpose.

The effect of balloon angioplasty on hypertension in atherosclerotic renal-artery stenosis. Dutch Renal Artery Stenosis Intervention Cooperative Study Group

BACKGROUND

Patients with hypertension and renal-artery stenosis are often treated with percutaneous transluminal renal angioplasty. However, the long-term effects of this procedure on blood pressure are not well understood.

METHODS

We randomly assigned 106 patients with hypertension who had atherosclerotic renal-artery stenosis (defined as a decrease in luminal diameter of 50 percent or more) and a serum creatinine concentration of 2.3 mg per deciliter (200 micromol per liter) or less to undergo percutaneous transluminal renal angioplasty or to receive drug therapy. To be included, patients also had to have a diastolic blood pressure of 95 mm Hg or higher despite treatment with two antihypertensive drugs or an increase of at least 0.2 mg per deciliter (20 micromol per liter) in the serum creatinine concentration during treatment with an angiotensin-converting-enzyme inhibitor. Blood pressure, doses of antihypertensive drugs, and renal function were assessed at 3 and 12 months, and patency of the renal artery was assessed at 12 months.

RESULTS

At base line, the mean (+/-SD) systolic and diastolic blood pressures were 179+/-25 and 104+/-10 mm Hg, respectively, in the angioplasty group and 180+/-23 and 103+/-8 mm Hg, respectively, in the drug-therapy group. At three months, the blood pressures were similar in the two groups (169+/-28 and 99+/-12 mm Hg, respectively, in the 56 patients in the angioplasty group and 176+/-31 and 101+/-14 mm Hg, respectively, in the 50 patients in the drug-therapy group; P=0.25 for the comparison of systolic pressure and P=0.36 for the comparison of diastolic pressure between the two groups); at the time, patients in the angioplasty group were taking 2.1+/-1.3 defined daily doses of medication and those in the drug-therapy group were taking 3.2+/-1.5 daily doses (P<0.001). In the drug-therapy group, 22 patients underwent balloon angioplasty after three months because of persistent hypertension despite treatment with three or more drugs or because of a deterioration in renal function. According to intention-to-treat analysis, at 12 months, there were no significant differences between the angioplasty and drug-therapy groups in systolic and diastolic blood pressures, daily drug doses, or renal function.

CONCLUSIONS

In the treatment of patients with hypertension and renal-artery stenosis, angioplasty has little advantage over antihypertensive-drug therapy.

Accuracy of normal-dose contrast-enhanced MR angiography in assessing renal artery stenosis and accessory renal arteries

OBJECTIVE

The purpose of this study was to evaluate the accuracy of breath-hold contrast-enhanced MR angiography in the assessment of renal artery stenosis and accessory renal arteries using a standard dose of gadolinium.

SUBJECTS AND METHODS

Thirty-eight patients suspected of having renal artery stenosis underwent MR angiography and intraarterial digital subtraction angiography, which was the method of reference. Three-dimensional gradient-echo MR subtraction angiography (TR/TE, 5.8/1.8 msec) was performed on a 1.5-T imager using a phased array body coil. Before imaging, a separate timing bolus sequence was used, administering 1.0 ml of contrast agent. Gadopentetate dimeglumine (15 ml) was injected using an MR power injector. Two observers, who were unaware of each other's interpretation and of MR findings, assessed digital subtraction angiography. Likewise, two other observers assessed MR angiography.

RESULTS

Digital subtraction angiography depicted 75 main and 17 accessory renal arteries (n = 92). All main renal arteries and 13 accessory renal arteries were identified on MR angiography. Compared with digital subtraction angiography, MR imaging correctly classified 57 of 66 arteries without a hemodynamically significant stenosis (0-49%), 22 of 22 arteries as significantly stenotic (50-99%), and four of four occluded arteries; five stenoses were overestimated. There was one false-positive finding of an accessory renal artery on MR angiography that was identified retrospectively on digital subtraction angiography. Interobserver agreement was high. Sensitivity and specificity for grading significant stenosis were 100% and 85%, respectively.

CONCLUSION

Contrast-enhanced MR angiography, using +/-0.1 mmol/kg of gadolinium, is an accurate method in the assessment of renal artery stenosis and accessory renal arteries.

[Malignant hypertension in a young man with renal artery occlusion diagnosed with magnetic resonance angiography]

A male aged 22 years developed a hypertensive crisis with encephalopathy after his antihypertensive medication had been discontinued with a view to extended diagnostics. Immediate intensive treatment led to rapid and complete recovery. By using gadopentetate acid enhanced magnetic resonance angiography it is possible to obtain a clear image of the morphology of the kidneys and the renal vasculature without the use of iodinated contrast media and arterial catheterisation. This technique revealed an occluded renal artery and a recent infarction that possibly had led to the serious and threatening events.

Adenosine-induced renal vasodilatation is prolonged in renal artery stenosis

OBJECTIVE

The objective of this study was to determine whether the response of renal blood flow (RBF) to adenosine infusions differs between hypertensive patients with and without renal artery stenosis (RAS).

DESIGN AND METHODS

Twenty-one hypertensive patients who underwent diagnostic angiography of the renal arteries were studied. Nine patients (median age 51 years; 45-61 interquartile ranges) were diagnosed as having essential hypertension (EH). Twelve patients (median age 52 years; 50-58) had hypertension and renal artery stenosis. In all patients three stepwise increasing doses of adenosine (1, 3 and 10 (microg/kg/min) were infused into the renal artery. RBF was measured before and during infusions by means of the 133xenon wash-out method. Arterial and venous plasma samples for renin concentration were obtained from the renal artery and renal vein. Intraarterial blood pressure and heart rate were monitored continuously.

RESULTS

Both groups were similar with respect to age, body mass index, mean arterial pressure and baseline RBF (EH: median 428; RAS 343 ml/min/100 g). Both groups showed a similar dose-related increase in RBF during adenosine infusions (normal kidneys: 9, 21 and 34% change vs baseline; stenotic kidneys: 16, 39 and 52% change vs baseline). Ten minutes after discontinuation of the adenosine infusion, RBF returned to baseline in the normal kidney group, but increased further in the stenotic kidney group (71% vs baseline; P = 0.033). Adenosine infusion did not affect the renin secretion in either group.

CONCLUSION

Both essential hypertensive patients and patients with renal artery stenosis show a dose-dependent vasodilatation following adenosine infusion. This vasodilatation is sustained after discontinuation of the adenosine infusion in patients with renal artery stenosis, suggesting a potentiated mechanism for vasodilatation induced by adenosine.

[Treatment of renal artery stenosis with intra-arterial stents]

In some patients with hypertension or renal insufficiency, renal artery stenosis can play a causative part. If fibromuscular dysplasia is the pathology of the stenosis, treatment of the stenosis by transluminal percutaneous renal angioplasty (TPRA) results in improvement of the concomitant hypertension in 80-90% of the patients. In case of atherosclerotic lesions 50% of the patients benefit by such treatment. In renal insufficiency TPRA of atherosclerotic lesions results in improvement of renal function in only one third of the patients. As restenosis and elastic recoil are seen as the prime determinants of this lack of success in atherosclerosis, intravascular stents were developed with the aim to accomplish a permanent dilation of the arterial lumen. In recent studies stent placement resulted in cure of high blood pressure in 0-16% of the patients and in improvement in 35-70%. The percentage of improvement must be viewed with caution because of the open design of these studies. Improvement of renal function was reported in 7-36% of the patients and worsening in 8-18%. Based on these outcomes stent placement in stenosed renal arteries should not be regarded as a routine clinical treatment.

Endothelin and active renin levels in essential hypertension and hypertension with renal artery stenosis before and after percutaneous transluminal renal angioplasty

OBJECTIVE

To determine whether active renin and endothelin levels in venous plasma differ between patients with renal artery stenosis and patients with primary hypertension. Among the patients with renal artery stenosis we also compared active renin and endothelin levels between subjects who had been cured or whose blood pressure had improved after treatment of the stenosis and those without a beneficial reaction after such treatment.

METHODS

We measured immunoreactive endothelin and active renin levels in peripheral venous plasma before and 1 h after angiotensin converting enzyme inhibition in 25 patients with primary hypertension and in 27 patients with hypertension and renal artery stenosis. Percutaneous transluminal angioplasty was performed in 21 patients of the latter group. For 11 patients of this group, hypertension was cured or there was an improvement, whereas 10 other patients did not respond to this treatment. Baseline active renin and endothelin levels were compared between these groups, as were the clinical characteristics of the patients.

RESULTS

Baseline endothelin levels were similar in members of the renal artery stenosis [median 3.6 pg/ml (range 1.4-11.7)] and in members of the no stenosis group [5.0 pg/ml (1.5-8.0)]. Also baseline endothelin levels did not differ between members of the successfully treated [3.6 pg/ml (1.8-8.9)] and unsuccessfully treated groups [3.75 pg/ml (1.4-8.3)]. Angiotensin converting enzyme (ACE) inhibition failed to cause a significant change in endothelin level in members of any of the patient groups. Although baseline renin levels differed significantly between members of the renal artery stenosis and no stenosis groups [40.2 microu/ml (0.9-543) versus 13.4 microu/ml (2.5-931), (P< 0.05)], there was no difference in baseline renin levels between the members of successful and unsuccessful groups [25.7 microu/ml (9.2-475.6) versus 65.3 microu/ml (12.3-542.6)]. ACE inhibition caused a significant increase in renin level in members of all groups except the unsuccessfully treated group.

CONCLUSIONS

Circulating endothelin levels did not differ significantly among patients with essential hypertension, hypertension with renal artery stenosis and proven renovascular hypertension and, although the renin-angiotensin system was clearly activated in members of the renovascular hypertension group, ACE inhibition did not affect their endothelin levels. These results suggest that endothelin does not play a direct role in the pathophysiology of renovascular hypertension.

Magnetic resonance angiography has a high reliability in the detection of renal artery stenosis

In this prospective study we examined the value of magnetic resonance angiography (MRA) in the imaging of the proximal renal arteries, with the main aim of detecting renal arterial stenosis, as compared with intraarterial digital subtraction angiography. The study was done among a group of 38 hypertensive patients seen in the outpatient department of the department of medicine of our university hospital. In all patients a magnetic resonance angiography and an intraarterial subtraction angiography of the renal arteries was made, and the outcomes of the investigations were compared. Clinical and biochemical data of the patients also were analyzed in relation to the presence or absence of a stenosis. In one patient, MRA resulted in technical failure because of unsuspected claustrophobia. Of the remaining 37 patients, 14 had renal artery stenosis. Of 12 patients in whom the stenoses were >50% of luminal surface on intraarterial digital subtraction angiography, eight were unilateral and four bilateral. All these stenoses were recognized by magnetic resonance angiography. There was also one false positive result by magnetic resonance. Thus, for the identification of stenoses >50%, magnetic resonance has a sensitivity of 100% and a specificity of 96%. Of the 12 accessory renal arteries seen on digital subtraction angiography, only three were identified by magnetic resonance angiography. We conclude that magnetic resonance angiography has great accuracy in depicting the main renal arteries and detecting clinically significant renal artery stenosis; however, the identification of accessory renal arteries is suboptimal and should be improved.

The place of renal scintigraphy in the diagnosis of renal artery stenosis. Fifteen years of clinical experience

BACKGROUND

Renal scintigraphy with radiolabeled pentetic acid (diethylenetriamine pentaacetic acid [DTPA]) or, more recently, mertiatide (mercaptoacetyltriglycine [MAG3]), with or without captopril challenge, is widely recommended as a diagnostic test for renal artery stenosis.

OBJECTIVES

To address (1) whether the diagnostic accuracy has been improved by the use of captopril and the introduction of mertiatide and (2) whether a renal scan that shows abnormalities is a useful criterion to select patients for renal arteriography.

PATIENTS AND METHODS

A standard diagnostic protocol, using both scintigraphy and arteriography, was followed in 505 consecutive high-risk hypertensive patients who were evaluated for renovascular hypertension at the University Hospital Dijkzigt, Rotterdam, the Netherlands, from 1978 to 1992.

RESULTS

Renal artery stenosis (> or = 50%) was present in 263 patients. When the single-kidney fractional uptake was used as a diagnostic criterion, a specificity of 0.90 was obtained at a cutoff value of 35% for the worst kidney in scintigraphy using pentetic acid without captopril challenge (n = 225) and at a cutoff value of 37% after captopril challenge (n = 280). This was associated with sensitivity levels of 0.65 and 0.68, respectively. The difference between the uptake of pentetic acid with and without captopril challenge in the 85 patients who were studied under both circumstances was no more accurate as a predictor of renal artery stenosis. In the 93 patients who were studied with mertiatide as well as with pentetic acid, both after captopril challenge, the diagnostic accuracy was no better with mertiatide than with pentetic acid; mertiatide failed to offer any advantage not only when the single-kidney fractional uptake was used as a criterion, but also with the use of other scintigraphic parameters (eg, time to peak, time to pyelum, overall shape of renographic curve, and kidney size).

CONCLUSIONS

The diagnostic accuracy of renal scintigraphy has not been improved by the introduction of mertiatide or by the use of captopril. The usefulness of scintigraphy as a diagnostic test for the presence of renal artery stenosis remains questionable. The physician will always confront either a substantial number of arteriograms that do not show abnormalities when renal scintigraphy is omitted as a screening step or a substantial number of missed diagnoses when a renal scan that shows abnormalities is used as a prerequisite for arteriography.

[Measurement of the body temperature of adults by rectal digital thermometer and the infrared tympanic thermometer: equally good results in the department of internal medicine]

OBJECTIVE

To examine whether, in clinical practice, the infrared tympanic thermometer shows temperature readings similar to those obtained with the rectal digital thermometer, so that the former can replace the latter.

DESIGN

Prospective comparative study.

SETTING

Academic Hospital, Nijmegen, the Netherlands.

METHOD

In 104 patients admitted to the department of medicine, body temperature was measured by both methods within approximately ten minutes. This was done on two successive days. The measurements were then analysed by plotting the difference between two measurements against their mean. Then the limits of agreement, which are the mean of the differences between the two measurements plus and minus 2 standard deviations, were determined. With both thermometers also duplicate measurements were made to study the repeatability.

RESULTS

The mean difference between the 2 methods in the first measurement was 0.15 degree C (SD: 0.56), in the second measurement it was 0.07 degree C (0.52). The limits of agreement were 1.27 degrees C and -0.97 degree C for the first comparisons and 1.13 degrees C and -0.99 degree C for the second comparisons. In the duplicate measurements, the mean difference between the first and the second measurement was 0.02 degree C (0.19) in the rectal measurement, and 0.09 degree C (0.23) in the tympanic measurement. The patients found the tympanic measurements significantly less painful and unpleasant than the rectal measurement. The mean time needed for the tympanic measurements (8 s) was ten times less than for the rectal measurements (79 s).

CONCLUSION

The results of this study show good agreement between the infrared tympanic thermometer and the rectal digital thermometer so that they may be regarded as interchangeable. The patients had a clear preference for the tympanic thermometer, which also took less time.

Clinical and biochemical criteria in the detection of renal artery stenosis

OBJECTIVE

To investigate methods to diagnose renal artery stenosis (RAS) among the general hypertensive population.

METHODS

We studied the value of clinical and biochemical characteristics at the outpatient clinic to identify subjects with a renal artery narrowing of more than 50% of the luminal surface among 1047 hypertensive patients. Included in the analysis were: blood pressure, age, sex, body mass index, endogeneous creatinine clearance, smoking and plasma renin activity.

RESULTS

Among the 1047 patients, 355 were selected for angiography. In this subgroup 104 patients (29%) had RAS. The subjects with RAS had significantly higher diastolic and systolic blood pressures than did those without stenosis. Forward stepwise logistical regression analysis showed that systolic blood pressure, stimulated plasma renin activity and smoking were the most predictive independent screening variables for the presence of RAS. Yet, none of these characteristics or their combinations were sufficiently sensitive to distinguish reliably between patients with essential hypertension and those with RAS. Sytolic blood pressure > 160 mmHg or diastolic blood pressure > 100 mmHg on automatic (Dinamap) recording as criteria selected a subgroup of patients with a RAS prevalence of 30%.

CONCLUSIONS

By using blood pressure screening criteria a subgroup of hypertensive patients with a high prevalence of RAS can be formed in whom further invasive tests for RAS are indicated and efficient.

Pattern recognition of loss of early systolic peak by Doppler ultrasound has a low sensitivity for the detection of renal artery stenosis

In a group of 57 hypertensive patients seen in the out-patient department, the authors did a prospective study to the value of pattern recognition of changes in early systolic peak by Doppler ultrasound (DU) in the examination of renal arteries, as compared with intra-arterial digital subtraction angiography. In five patients (8.7%) DU resulted in technical failure, in one because of the inability to hold breath long enough, in one because the Doppler signals from one part of the kidney were unclear and in three because overlying adipose tissue hindered the examination. Among the remaining 52 patients, 13 had unilateral and six bilateral stenoses greater than 50% of the luminal surface on angiography. By DU 10 patients with a stenosis were identified, one of which was a false positive result. Of the remaining nine, six patients had a unilateral stenosis and three a bilateral stenosis that was identified as unilateral by ultrasound. Therefore, none of the bilateral stenosis was identified as such by DU. Thus, for the detection of renal artery stenoses greater than 50% visual waveform analysis of DU signals has a sensitivity of 47% and a specificity of 97%. The conclusion is therefore that the DU procedure employed in this study has a limited value in the examination of the renal arteries of hypertensive patients with the aim to detect renal arterial stenosis.

Urinary prostaglandin and prostaglandin metabolite excretion in patients with essential hypertension or hypertension with renal artery stenosis

BACKGROUND

Recent studies have reported elevated prostaglandin levels in patients with renal artery stenosis and hypertension. To investigate whether a distinction between essential hypertension and hypertension with renal artery stenosis is possible by measuring eicosanoid excretion, we studied the excretion of these compounds in patients with essential hypertension and in hypertensives with concomitant renal artery stenosis.

METHODS

The 24-h urinary excretion of metabolites of prostaglandin I2, prostaglandin E2 and metabolites of thromboxane A2 was sampled under standardised conditions, in 15 patients with essential hypertension and in 15 patients with unilateral renal artery stenosis with hypertension. Also clinical and biochemical characteristics of the subjects were analysed.

RESULTS

The patients with renal artery stenosis had significantly lower excretion of prostaglandin I2 than did the essential hypertensive patients. However, the overlap in the values was large, thus not allowing a diagnostic differentiation according to urinary prostaglandin I2 levels. The excretion of prostaglandin E2 and of metabolites of thromboxane A2 showed no significant differences among the groups.

CONCLUSIONS

Measurement of urinary prostaglandin or prostaglandin metabolite excretion did not contribute to the non-invasive detection of the presence of a renal artery stenosis in the patients in this study.

Doppler ultrasound scanning in the detection of renal artery stenosis in hypertensive patients

The diagnostic accuracy of Doppler ultrasound in the detection of renal arterial disease has been assessed in a prospective study of 61 hypertensive patients. The findings of Doppler ultrasound were compared with the results of renal angiography. In 15 patients (24.5%) no accurate Doppler signs could be obtained and the Doppler ultrasound examination was considered a technical failure. Of the remaining 46 patients, 24 had renal artery stenosis. Nine of the stenoses were not detected by Doppler ultrasound and in three patients a false positive diagnosis of renal artery stenosis was made. The sensitivity of Doppler ultrasound was 62.5%, the specificity 86.4% and the overall diagnostic accuracy was 73.9%. By comparing the 15 patients in whom Doppler ultrasound failed with the 46 in whom it was successful, age appeared to be higher and creatinine clearance lower in the failure group. By comparing the 34 patients with true positive and true negative results with the 12 patients with false results, no significant differences were found. In a multivariate analysis, higher age showed a significant relation to failure of Doppler ultrasound. Doppler ultrasound has limited value in the screening of hypertensive patients for renal artery stenosis.

First dose hypotension after captopril; can it be predicted? A study of 240 patients

We have studied prospectively the acute blood pressure lowering effect on an oral dose of captopril, 25 mg in 240 hypertensive patients. The mean relative reduction of systolic and diastolic BP was 16 and 15% respectively and the mean time to the mean arterial pressure nadir was 59 minutes. Systolic BP fell by more than 30% in 4.6% of patients and diastolic BP and mean arterial pressure dropped by more than 30% in 4.2 and 3.3% of patients respectively. Patients over 60 years of age showed a significantly larger fall in systolic and diastolic BP. Patients with renal artery stenosis reached the BP nadir in a significantly shorter time compared with patients with essential hypertension (50.5 vs. 59.7 minutes, P less than 0.05) and showed a significantly larger fall in systolic BP (20.7 vs. 15.4%, P less than 0.05). A forward stepwise regression analysis showed that only baseline plasma renin activity had a significant relation to the fall in BP (P less than 0.01, R = 0.57). We conclude that according to our definition of a greater than 30% decrease of the mean arterial pressure, a first dose hypotension after captopril was seen in 3.3% of 240 patients. Captopril treatment should be introduced carefully since not all those patients at risk of hypotension can be identified in advance.

The effect of caffeine on renal vein renin concentration in patients with renal arterial disease

The aim of this study was to investigate whether caffeine stimulates selectively renal vein renin levels at the side of unilateral stenosis in patients with renovascular hypertension. In this study seven of the involved patients had renal arterial stenosis and four had no stenosis. Four of the seven patients with a stenosis had retrospectively-proven renovascular hypertension. Renal vein renin sampling was performed before and after intravenous administration of caffeine. Caffeine did not induce any consistent effect on plasma renin activity in the renal veins, either on the stenotic side or on the contralateral side in patients with renovascular hypertension. There were no consistent caffeine mediated changes in systemic plasma renin activity.

The value of tests predicting renovascular hypertension in patients with renal artery stenosis treated by angioplasty

The aim of this study was to evaluate tests predicting renovascular hypertension. This was done by relating the results of renal vein renin tests, the captopril test, and renal scintigraphic tests to the blood pressure outcome 12 months after relief of renal artery stenosis by percutaneous transluminal renal angioplasty in 31 patients. Cure was seen in eight (26%). Improved blood pressure was obtained in 12 patients (39%), and in 11 patients (35%), the result for blood pressure was a failure. The accuracies of the two mathematical models used to analyze the renal vein renin assays were 44% and 60%. The captopril test showed a sensitivity of 36% and an accuracy of 43%. Renal captopril technetium Tc 99m-labeled pentetic acid scintigraphy gave a sensitivity of 60%. Stepwise logistic regression analysis of clinical variables in relation to blood pressure response revealed age as the only factor significantly related to blood pressure outcome. We conclude that the tests used are unfit for helping select patients for percutaneous transluminal renal angioplasty and that age may have an important influence on outcome.