Captopril renography and duplex Doppler sonography in the diagnosis of renovascular hypertension

Background. The purpose of this prospective study was to determine the clinical usefulness of captopril renal scintigraphy and duplex Doppler sonography in detecting haemodynamically significant renal artery stenosis (⩾60%) and predicting cure or improvement of hypertension following revascularisation. Methods. Twenty-eight patients with moderate or high index of clinical suspicion of renovascular hypertension underwent both captopril renal scintigraphy and duplex Doppler sonography before undergoing renal angiography. Patients with angiographically proved (⩾60%) RAS were treated by percutaneous transluminal renal angioplasty unless it was contraindicated. Results. The results of captopril renal scintigraphy and duplex Doppler sonography were compared by renal angiography of 45 renal arteries in 28 patients. Eleven renal arteries were excluded from further comparison, because no accurate Doppler signal could be obtained. The sensitivity and specificity of captopril renal scintigraphy in the identification of RAS (⩾60%) was 78% and 81% respectively. The sensitivity of duplex Doppler sonography was 83% and the specificity was 81%. Positive predictive values of both tests for blood pressure cure or improvement after PTRA were 86% for CRS and 85% for DDS. Conclusions. Captopril renal scintigraphy and duplex Doppler sonography are comparable tests for detection of patients with haemodynamically significant renal artery stenosis (⩾60%). Positive predictive values of both tests for cure or improvement of hypertension after percutaneous transluminal renal angioplasty are good and comparable.     

Intraoperative duplex sonography during renal artery reconstruction

To assess renal duplex sonography as an intraoperative study to detect technical defects during repair, 57 renal artery reconstructions in 35 patients were studied. Sixteen men and 19 women (mean age, 62 years) underwent unilateral (13 patients) or bilateral (22 patients) renal artery repair to 57 kidneys. Methods of repair included aortorenal bypass grafting in 29 cases (20 saphenous vein, 5 polytetrafluoroethylene, 4 Dacron), reimplantation in 7, transrenal thromboendarterectomy with patch angioplasty in 13, and transaortic extraction thromboendarterectomy in 8. Branch renal artery repair was required in six cases (five in vivo, one ex vivo). Fourteen patients had combined aortic replacement (11 patients: 8 abdominal aortic aneurysms, 3 aortic occlusions) or visceral artery reconstruction (three patients: three superior mesenteric artery thromboendarterectomies, one inferior mesenteric artery thromboendarterectomy). Intraoperative renal duplex sonography (mean scan time, 4.5 minutes) was complete in 56 of 57 repairs (98%), and renal duplex sonography was normal in 44 repairs (77%). Overall, B-scan defects were present in 13 repairs (23%). Six of these (11%) were defined as major B-scan defects by Doppler spectra with focal increases in peak systolic velocity greater than or equal to 2.0 meters/sec (major defect, mean renal artery peak systolic velocity, 3.1 m/sec), which prompted immediate operative revision. Seven B-scan defects were defined as minor by Doppler spectra (minor defect, mean renal artery, peak systolic velocity, 0.7 m/sec) and were not revised. Postoperative evaluation (range, 1 to 22 months; mean follow-up, 12.4 months) of 55 renal artery repairs in 34 operative survivors (surface renal duplex sonography, 33 patients; renal angiography, 9 patients) demonstrated 42/43 renal artery repairs with normal intraoperative renal duplex sonography, and 6/6 repairs with minor B-scan defects were patent and free of critical stenosis. Of the 6 renal artery revisions prompted by major B-scan defects, 4 remained patent, 1 stenosed, and 1 occluded. Our experience suggests that intraoperative renal duplex sonography during renal artery repair provides valuable anatomic and physiologic information. Renal artery repairs with normal renal duplex sonography and minor B-scan defects without Doppler spectral changes demonstrated 98% patency without critical stenosis at 12.4 months of mean follow-up. However, major B-scan defects defined by a focal increase in renal artery peak systolic velocity should be considered for immediate correction.     

Clinical implications of power Doppler three-dimensional ultrasonography

Power Doppler ultrasonography displays an estimate of the entire power contained in that part of the received radiofrequency ultrasound signal for which a phase shift corresponding to the motion of the target is detected. In contrast, conventional color Doppler imaging displays Doppler frequency shift information. Few reports have been published on the clinical utility of three-dimensional power Doppler ultrasonography in vascular patients. This study analyzed our experience of the clinical utility of this technology. Fifty-three patients selected out of 281 who were referred to our vascular laboratory underwent both conventional color duplex ultrasonography and power Doppler ultrasonography for the following indications: the question of subtotal versus total arterial occlusion, tortuous artery with limited imaging on color duplex ultrasonography, the presence of significant disease by Doppler ultrasonography with limited imaging, deep-lying arteries with an obscure orifice (e.g., renal artery), and heavily calcified arteries. The power Doppler ultrasonography portion of the examination was considered of positive diagnostic value if the final impression was different from that of conventional color duplex ultrasonography. A positive diagnostic value was achieved in 22 of 29 (76%) carotid artery examinations, 10 of 14 (71%) peripheral artery examinations, 4 of 5 (80%) renal artery examinations, and 3 of 5 (60%) aortoiliac examinations. Overall, positive diagnostic value was achieved by adding power Doppler ultrasonography in 39 of 53 patients (74%). Five of six patients (83%) who were felt to have carotid occlusion by color duplex ultrasonography were confirmed to have subtotal occlusion by power Doppler ultrasonography. Similarly, 6 of 8 patients (75%) with questionable subtotal versus total peripheral arterial occlusion by color duplex ultrasonography were confirmed to have subtotal occlusion by power Doppler ultrasonography. Four of five patients' (80%) renal examinations had a positive diagnostic value, which included three patients in whom the orifice of renal arteries was not seen by color duplex ultrasonography. Three-dimensional power Doppler ultrasonography can be more readily applied to clinical practice. Power Doppler ultrasonography is capable of defining the severity or extent of vascular disease, particularly in differentiating subtotal from total arterial occlusion.     

Evaluation of renal transplant dysfunction by duplex Doppler sonography: a prospective study and review of the literature

A disconcertingly wide variation exists in the literature as to the accuracy of duplex Doppler sonography in the detection of acute renal transplant rejection. Sensitivities range from 9% to 76%. In an attempt to explain the disparity of results, we undertook a double-blind prospective study of the accuracy of duplex Doppler ultrasound in the detection of acute rejection in renal transplants. We scanned 49 consecutive patients with a total of 65 biopsies; 46 biopsies in 33 consecutive patients were included in our study. In our population, the prevalence of acute rejection was 61% (28/46). Using a resistive index (RI) cutoff of greater than 0.90 based on the main renal artery flow pattern, the sensitivity of our test was 43%, with a 67% specificity. The positive predictive value was 67%. Our results are contrasted and compared with the published data from other groups in a critical survey of the literature. We conclude that duplex Doppler sonography alone is inadequate to evaluate acute rejection in renal transplants.     

Noninvasive radiological diagnosis of renal vein thrombosis in renal transplantation.

Thrombosis of the allograft renal vein is a rare complication of renal transplantation. Of 557 consecutive renal transplants performed between January 1, 1985 and November 30, 1989, 3 cases occurred for an over-all incidence of 0.4%. In 2 cases the diagnosis was made preoperatively with renal scintigraphy and duplex Doppler sonography. No graft was salvaged, despite timely diagnosis in 2 patients. We conclude that the diagnosis of renal vein thrombosis in the renal allograft recipient should be suspected clinically and by the radiographic findings of absent perfusion on renal scintigraphy, and the detection of an arterial signal, albeit abnormal, on duplex Doppler sonography. When diagnosed, nephrectomy appears to be the only treatment.     

Comparison of selective internal iliac pharmaco-angiography, penile brachial index and duplex sonography with pulsed Doppler analysis for the evaluation of vasculogenic (arteriogenic) impotence

Between July 1987 and February 1988 selective internal iliac angiography was performed before and after intracavernous injection of papaverine plus phentolamine in 43 patients with erectile dysfunction. In 63% of the patients stenosis or occlusion of the pudendal artery was found. The penile brachial index was calculated and duplex sonography with pulsed Doppler analysis was performed in 23 patients. Angiography and penile brachial index correlated in only 39% of the patients, whereas selective internal iliac angiography and duplex sonography correlated in 91% (21 of 23). In 2 patients duplex sonography with pulsed Doppler analysis rendered better information about penile arterial perfusion than did angiography.     

Intraoperative renal duplex sonography: a valuable method for evaluating renal artery reconstructions.

OBJECTIVES: to determine the ability of duplex sonography to intraoperatively detect technical problems with renal artery reconstructions. DESIGN: retrospective evaluation of a standard protocol. PATIENTS AND METHODS: the outcome of intraoperative duplex was compared with postoperative angiography, surface duplex, MRA, echo or direct inspection in case of re-exploration in 77 renal artery reconstructions in 62 patients. These included six extracorporeal reconstructions, eight and 17 reconstructions with an artery and autogenous vein respectively, 10 renal artery re-implantations in the aorta (prosthesis), 32 endarterectomies and four reconstructions of kidney transplant vessels. RESULTS: intraoperative duplex was normal in 67/73 reconstructions with sufficient data. In six cases technical problems were revealed by intraoperative duplex and the reconstruction was re-explored. After re-exploration intraoperative duplex was normal in all cases. Confirmatory studies demonstrated normal results in 61/64 reconstructions with normal intraoperative duplex and abnormal results in 6/6 reconstructions with technical problems revealed by intraoperative duplex. Three reconstructions with normal intraoperative duplex occluded as demonstrated by angiography less than 2 weeks after surgery. CONCLUSIONS: renal duplex sonography is a valuable method available for intraoperative detection of technical problems. Haemodynamic duplex data were less important than B-mode imaging in discriminating between normal and abnormal reconstruction.     

Evaluation of the vertebral arteries with duplex sonography

Using duplex sonography, we have routinely evaluated the vertebral arteries as part of the carotid artery examination in 453 consecutive patients over a 6-month period. Sixty-two of these 906 vessels could not be adequately evaluated, primarily because these vessels lay too deep within the vertebral structures, resulting in a technical failure rate of 6.8%. For the remaining 844 vessels, 74.4% were considered normal by Doppler flowmeter spectral analysis. Angiographic correlation was available for 224 vessels; of 155 judged normal by duplex sonography, 144 (93%) were shown to be normal or have only mild atherosclerotic disease. Eleven vessels were considered either occluded or to have severe disease by duplex sonography, and angiography showed this to be the case in 10 (91%) vessels. Unusually strong vertebral artery flow was associated with hemodynamically significant carotid or contralateral vertebral atherosclerotic disease or subclavian steal 82% of the time. Twelve cases of subclavian steal, only one of which was symptomatic, were identified by duplex sonography; four of these were confirmed by angiography. Angiographic correlation was available for 229 vessels in which duplex evaluation showed vertebral artery flow to be moderately damped. In 11 of these (38%), angiography showed greater than 50% stenosis. Angiography judged the remaining 18 vessels in this group normal; these vessels may represent a small subgroup of patients with normal anatomy or only mild atherosclerotic disease, but with hemodynamic dysfunction that can be identified with the duplex technique.     

Detection of significant renal artery stenosis with color Doppler sonography: combining extrarenal and intrarenal approaches to minimize technical failure

BACKGROUND: Renal artery disease can cause both hypertension and renal failure, and color Doppler sonography (CDS) may be a good screening method to detect it. Presently reported techniques of Doppler sonography have either a high rate of technical failure (4-42%), or low sensitivity and specificity, or detect only stenoses greater than 70%, or exclude patients with renal failure from analysis. In previous studies Doppler detection of renal artery stenosis (RAS) was based either on increased intrastenotic velocity or on the detection of post-stenotic Doppler phenomena. In the present prospective study these two approaches were combined to detect RAS (> or = 50% diameter reduction) in 226 consecutive patients (144 with normal and 82 with impaired renal function). METHODS: Stenosis of 50% or more was diagnosed if the maximal systolic velocity in the main renal artery was more than 180 cm/sec and velocity in the distal renal artery less than one quarter of the maximum velocity. When these velocities could not be determined a diagnosis of RAS was made when the acceleration time in intrarenal segmental arteries exceeded 70 msec. All patients subsequently underwent arteriography as the gold standard for the detection of RAS. RESULTS: With this combined approach, the technical failure rate of CDS was 0% in both patients with normal and those with impaired renal function. The mean time required for the Doppler investigation was 17 minutes. The sensitivity and specificity for detection of a significant stenosis in a given vessel (including accessory arteries), as compared to angiography, were 96.7% and 98.0%. CONCLUSION: Color Doppler sonography, evaluating both main renal and intrarenal arteries is an ideal screening method for detection of RAS of 50% or more because it allows accurate and rapid detection of stenosis in all patients, irrespective of renal function.     

Imaging of renal artery stenosis

Renal artery stenosis is the cause of progressive ischemic nephropathy and of renovascular hypertension. Due to the invasiveness of arteriography, which is claimed to be the gold standard at the present time, several noninvasive imaging techniques are available. Colour Doppler sonography is cost-effective, but magnetic resonance angiography and computer tomography are more expensive; however, both are potential candidates for the definition of a new gold standard. Evaluation of renal vasculature by means of Doppler sonography includes intra- and extrarenal scanning as well as power Doppler and the use of contrast agents for enhancement of the Doppler signals. Computed tomography angiography is a minimally invasive method for the diagnosis of renal artery stenosis. There is high diagnostic accuracy that is not significantly different from that of angiography with respect to main and accessory renal arteries and detection of clinically significant renal artery stenoses. The main advantages over angiography are the use of an intravenous approach, and direct information provided about the vessel wall and adjacent structures. However, the nephrotoxicity of contrast material remains a major concern. Magnetic resonance angiography of the abdominal aorta and renal arteries has advanced considerably over the past few years. Recently developed breath-hold three-dimensional magnetic resonance angiography provides a new promising, noninvasive technique to evaluate the abdominal aorta and its large branch vessels. Using this technique, high sensitivity and specificity is achieved. The improved image quality and the ability to detect vascular lesions is due to short acquisition time with elimination of respiratory artifacts over an entire imaged volume by single breath-hold acquisition. Computed tomography angiography with its fast acquisition time and high spatial resolution compares favorably with magnetic resonance angiography and colour Doppler sonography. However, as compared with Doppler sonography and magnetic resonance angiography, computed tomography angiography images display only anatomic information and lack of flow sensitivity.     

Duplex and transcranial sonography in the preoperative evaluation of cerebrovascular circulation before heart operations

Fifty unselected patients undergoing open heart surgery (OHS) were examined by duplex and transcranial Doppler sonography. Two high degree (greater than 75%) carotid stenosis were found in 70 carotid arteries of 35 patients with coronary artery disease. Fourteen vessels had unmistakable signs of extracranial vascular disease whilst 54 carotid arteries were identified as normal. Two high degree (greater than 75%) carotid stenosis were found in 30 vessels of 15 patients with valvular disease. Seven other vessels had a low grade stenosis or excessive atheroma, whereas 21 were identified as normal. The rate of about 5-10% asymptomatic high grade carotid stenosis in patients undergoing OHS justifies routine noninvasive examination of the cerebral circulation by duplex and transcranial Doppler sonography. Patients with high grade stenosis are offered a follow-up preventive programme against cerebral infarction, which consists of 3 steps: 1. anti-platelet aggregating drugs, 2. periodic control examinations by duplex and transcranial Doppler sonography, and 3. continued evaluation of indication for carotid endarterectomy.     

Karotisstenose als Zusatzbefund bei koronarer Herzkrankheit

Carotid stenosis is frequent in patients with coronary artery disease (CAD). In the literature, 9-28% of patients with CAD have additional carotid artery stenosis, predictors of which are advanced age, smoking, diabetes mellitus, arterial hypertension, coronary multivessel disease, and peripheral arterial disease. Moreover, patients with unstable coronary syndromes and those with elevated inflammatory markers such as C-reactive protein or fibrinogen more often have concomitant CAD and carotid artery stenosis. The long-term prognosis of these patients is worse than with CAD only. Therefore, patients with CAD should be screened for additional carotid artery stenosis, especially if coronary artery bypass grafting is planned. Continuous wave Doppler sonography and color-coded duplex sonography are suitable methods to screen for carotid artery stenosis.     

Renal arterial duplex Doppler ultrasound in dogs with urinary obstruction

Recent clinical studies using duplex Doppler sonography identified an alteration in renal arterial blood flow in obstructed hydronephrotic kidneys that reportedly can be used to distinguish obstructive from nonobstructive collecting system dilatation. We attempted to verify these clinical findings and establish the temporal relationship of the alteration in the Doppler spectrum to the onset of urinary obstruction by evaluating surgically induced urinary obstruction in dogs. We performed laparotomies on 11 dogs, with the left ureter isolated and ligated in five dogs, and left intact in six dogs (control group). Duplex Doppler examination of the left renal arteries performed nine times during the first postoperative month identified a statistically significant difference (p less than .05) in the Doppler resistive index calculation between the two groups on days 1, 2, 4, and week 4. A resistive index discriminatory threshold of 0.7 (greater than 0.7, obstructed; less than 0.7, nonobstructed) produced a test sensitivity of 74% and specificity of 77%. We conclude from our study that renal arterial duplex Doppler sonography can detect a change in renal perfusion as a result of urinary obstruction and that this change can be detected as early as 24 hours after obstruction. However, high false-positive and false-negative rates may limit the ability of this modality to reliably distinguish obstructive from nonobstructive collecting system dilatation.     

Renal duplex sonography: evaluation of clinical utility

With the exception of conventional angiography, no previously proposed screening test has the necessary sensitivity/specificity to guide further evaluation for correctable renovascular disease. Recently, renal duplex sonography has been suggested as a useful substitute in such screening for renovascular disease. This report analyzes our data collected over the past 10 months in evaluation of renal duplex sonography to examine its diagnostic value. The study population for renal duplex sonography validity analysis consisted of 74 consecutive patients who had 77 comparative renal duplex sonography and standard angiographic studies of the arterial anatomy to 148 kidneys. Renal duplex sonography results from six kidneys (4%) were considered inadequate for interpretation. This study population contained 26 patients (35%) with severe renal insufficiency (mean 3.6 mg/dl) and 67 hypertension (91%). Fourteen patients (19%) had 20 kidneys with multiple renal arteries. Bilateral disease was present in 22 of the 44 patients with significant renovascular disease. Renal duplex sonography correctly identified the presence of renovascular disease in 41 of 44 patients with angiographically proven lesions, and renovascular disease was not identified in any patient free of disease. When single renal arteries were present (122 kidneys), renal duplex sonography provided 93% sensitivity, 98% specificity, 98% positive predictive value, 94% negative predictive value, and an overall accuracy of 96%. These results were adversely affected when kidneys with multiple (polar) renal arteries were examined. Although the end diastolic ratio was inversely correlated with serum creatinine (r = -0.3073, p = 0.009), low end diastolic ratio in 35 patients submitted to renovascular reconstruction did not preclude beneficial blood pressure or renal function response. We conclude from this analysis that renal duplex sonography can be a valuable screening test in the search for correctable renovascular disease causing global renal ischemia and secondary renal insufficiency (ischemic nephropathy). Renal duplex sonography does not, however, exclude polar vessel renovascular disease causing hypertension alone nor does it predict hypertension or renal function response after correction of renovascular disease.     

彩色多普勒血流定量技术评价系统性红斑狼疮患者肾皮质血流

目的探讨多普勒超声血流定量技术评价系统性红斑狼疮（SLE）患者肾脏皮质血流灌注的临床价值。方法选取SLE患者21例（SLE组）,22名健康人作为正常对照组。采用Philips IU22超声诊断仪测量肾叶间动脉、小叶间动脉阻力指数（RI）;以定量分析软件计算反映。肾脏皮质血流灌注的各项指数：血管指数（VI）、血流指数（FI）和血管一血流指数（VFI）。并对SLE组与正常对照组各指标进行比较分析。结果SLE患者肾皮质彩色血流信号较对照组稀疏,血流束纤细,到达皮质边缘的彩色血流信号较正常组减少;SLE患者叶间动脉、小叶间动脉R1值与正常对照组差异无统计学意义（P〉0．05）,VI、FI、VFI值均低于正常对照组,差异有统计学意义（VI、VFI,P〈0．01;FI,P=0．01）。结论SLE患者的肾血流灌注显著低于正常对照组;彩色多普勒超声血流定量技术为诊断SLE肾损害提供了一种便捷、实时、无创的新方法。     

Correlation of transcranial Doppler and noninvasive tests with angiography in the evaluation of extracranial carotid disease

To evaluate the usefulness of transcranial Doppler sonography in determining severity of extracranial carotid disease, we compared transcranial Doppler, ocular pneumoplethysmography, Doppler spectral analysis, and duplex scanning data to information derived from cerebral angiography. Fifty-one consecutive patients with unilateral extracranial internal carotid artery stenosis or occlusion were selected. Transcranial Doppler indexes included the peak systolic flow velocity in the middle cerebral artery ipsilateral to the stenosed internal carotid artery (iMCAFV), the difference between the peak systolic flow velocities in the middle cerebral artery ipsilateral and contralateral to the stenosed internal carotid artery (dMCAFV), and the peak systolic flow velocity in the anterior cerebral artery contralateral to the stenosed internal carotid artery (cACAFV). The minimal residual lumen determined angiographically was used as the index of internal carotid artery stenosis. Linear regression analysis with minimal residual lumen as the dependent variable and transcranial Doppler and noninvasive tests as independent variables showed the following correlation coefficients: (1) dMCAFV and cACAFV, R2 = 0.3170; (2) ocular pneumoplethysmography, R2 = 0.4798; (3) dMCAFV, cACAFV, delta ocular pneumoplethysmography, duplex scanning, and spectral analysis R2 = 0.6382; (4) ocular pneumoplethysmography, duplex scanning, and spectral analysis, R2 = 0.6491; (5) iMCAFV, no association. These results were supported by sensitivity and specificity as well as bivariate analysis. We conclude that transcranial Doppler did not significantly add to the information obtained by our noninvasive battery of tests in the evaluation of unilateral extracranial carotid disease.     

彩色多普勒对肾血管病变诊断价值探讨

以双功能和彩色多普勒超声诊断５５例肾血管病变，包括肾动脉狭窄、肾小动脉硬化、肾动脉发育不良、肾动静脉畸形、急性肾静脉血肾静脉曲张。与其中３８例有完整肾血管造影检查资料的结果对照，超声诊断符合率９５％。结果认为综合多普勒定量指标、典型的多普勒频谱形态和征象各的彩色血流图象，能够对多种肾血管病变出准确诊断。     

Dilated renal collecting systems: differentiating obstructive from nonobstructive dilation using duplex Doppler ultrasound

Two patients with ileal loop urinary diversions, studied with real-time and Doppler sonography ("duplex sonography") of the kidneys, were shown to have dilated intrarenal collecting systems. Resistive index measurements calculated from the Doppler signal correctly identified obstructive dilatation in 1 case and nonobstructive dilatation in the other.     

Diagnosis of renal artery occlusion by duplex sonography and successful lysis therapy.

A case of partial renal artery occlusion in a 44-year-old man is reported. Diagnosis was established by Duplex sonography and confirmed by digital subtraction angiography. Subsequently performed local lysis therapy with recombinant tissue plasminogen activator achieved partial revascularization. Doppler evaluation of renal blood flow is useful to detect renal infarction.     

Diagnostic procedure in renovascular hypertension

Detection of a renal artery stenosis (RAS) as a cause of arterial hypertension is of great practical importance because dilatation of the stenosis frequently results in an improvement or cure of the hypertension. In recent years, a number of screening procedures aimed at diagnosing renovascular hypertension have been developed, e.g., duplex sonography of the renal arteries, determination of plasma renin activity, or renal scintigraphy following administration of captopril. The possibilities and limitations of these screening procedures are described here. The best method for detecting renal artery stenosis is angiography, which can now be performed on an outpatient basis, using thin catheters.