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Biomedical subjects

R E Zierler

Publications and source records attributed to R E Zierler.

At least 19 recordsLinked to original sources
PubMed1998

Carotid and lower extremity arterial disease in patients with renal artery atherosclerosis.

BACKGROUND: Atherosclerotic lesions of the carotid and lower extremity arteries may be associated with renal artery stenosis and influence the management of patients with renal artery disease. OBJECTIVE: To document the prevalence and clinical features of carotid and lower extremity arterial disease in patients with renal artery atherosclerosis. METHODS: An analysis of baseline data on 149 patients enrolled in a prospective natural history study of atherosclerotic renal artery stenosis. Patients with at least 1 abnormal renal artery by duplex scanning were eligible. Carotid artery disease was evaluated by duplex scanning, and ankle/brachial indices were used to assess the lower extremity arteries. Disease at each of the 3 arterial sites was classified as mild, moderate, or severe based on the extent of involvement on both sides. Serum urea nitrogen, creatinine, and lipid levels were also measured. RESULTS: Severe renal, carotid, or lower extremity arterial disease was present in 44%, 19%, and 21% of the patients, respectively. There was a trend for patients with increasing degrees of renal artery disease to have increasing degrees of carotid and lower extremity arterial disease. The prevalence of severe carotid artery disease increased from 7% in the mild renal artery group to 28% in the severe renal artery group. Clinical factors that were most predictive of severe disease were elevated apolipoprotein B levels for the renal arteries, high serum urea nitrogen or creatinine levels for the carotid arteries, and smoking for the lower extremity arteries. CONCLUSIONS: There was a strong association between severe renal artery atherosclerosis and severe carotid artery disease. Patients with renal artery disease also had a high prevalence of lower extremity arterial disease. In this patient population, screening for lower extremity arterial disease can be reserved for those with signs or symptoms of peripheral ischemia. Noninvasive carotid screening is justified in patients with renal artery disease to detect asymptomatic lesions that require either immediate surgical treatment or serial follow-up for disease progression.

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PubMed1998

Clinical evidence of contralateral renal parenchymal injury in patients with unilateral atherosclerotic renal artery stenosis.

It has been postulated that the kidney contralateral to a significant renal artery stenosis may be at risk for accelerated arteriolar nephrosclerosis. Duplex ultrasound is capable of detecting and classifying renal artery stenosis and examining parenchymal flow. Renal flow patterns are a reflection of resistance, which increases with parenchymal pathology. One-hundred fifty-one patients with atherosclerotic renal artery stenosis (ARAS) were prospectively studied with duplex ultrasonography. Renal arteries were classified as normal, <60% stenosis, > or =60% stenosis, or occluded. The renal artery end-diastolic ratio (EDR) (end-diastolic velocity/peak systolic velocity) was measured. EDR decreases as resistance to flow increases. There were 81 patients with a unilateral > or =60% ARAS. The EDR was significantly lower in the kidney contralateral to the > or =60% ARAS (0.27 +/- 0.08 versus 0.30 +/- 0.08; p = 0.001, paired t-test). The absolute difference in EDR was even more pronounced in the subgroup of 15 diabetic patients with a > or =60% ARAS (0.22 +/- 0.08 versus 0.27 +/- 0.08; p = 0.004). This study offers clinical evidence that a unilateral hemodynamically significant ARAS is associated with the development of arteriolar nephrosclerosis in the contralateral kidney. These results have important implications on blood pressure control, renal function, and response to renal revascularization in this patient population.

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PubMed1998

Risk of atrophy in kidneys with atherosclerotic renal artery stenosis.

The goal of this study was to determine the incidence of and risk factors for renal atrophy among kidneys with atherosclerotic renal artery stenosis (ARAS). Participants with at least one ARAS were followed prospectively with duplex scans performed every six months. Renal atrophy was defined as a reduction in renal length of greater than 1 cm. A total of 204 kidneys in 122 subjects were followed for a mean of 33 months. The two-year cumulative incidence (CI) of renal atrophy was 5.5%, 11.7%, and 20.8% in kidneys with a baseline renal artery disease classification of normal, <60% stenosis, and > or = 60% stenosis, respectively (P = 0.009, log rank test). Other baseline factors associated with a high risk of renal atrophy included a systolic blood pressure > 180 mm Hg (2-year CL = 35%, P = 0.01), a renal artery peak systolic velocity > 400 cm/second (2-year CI = 32%, P = 0.02), and a renal cortical end diastolic velocity < or = 5 cm/second (2-year CI = 29%, P = 0.046). The number of kidneys demonstrating atrophy per participant was correlated with elevations in the serum creatinine concentration (P = 0.03). In patients with ARAS, there is a significant risk of renal atrophy among kidneys exposed to elevated systolic blood pressure and among those with high-grade ARAS and low renal cortical blood flow velocity as assessed by renal duplex scanning. The occurrence of renal atrophy is well-correlated with changes in the serum creatinine concentration.

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PubMed1997

Results of percutaneous transluminal angioplasty for atherosclerotic renal artery stenosis: a follow-up study with duplex ultrasonography.

PURPOSE: The short and long-term anatomic results of percutaneous transluminal renal angioplasty (PTRA) in the treatment of atherosclerotic renovascular disease have been poorly documented because of a lack of follow-up arteriography. The purpose of this study was to evaluate the anatomic results of PTRA with serial duplex examinations. METHODS: The records of 41 patients who underwent 52 primary PTRA procedures and had subsequent duplex follow-up of at least 6 months were reviewed. After PTRA, renal arteries were classified as normal, < 60% stenosis, > or = 60% stenosis, or occluded on the basis of previously validated duplex criteria. RESULTS: The study group included 26 men and 15 women with a mean age of 65 years, who were observed for a mean interval of 34 months. Endovascular stents were placed in 12 of the 52 arteries. The initial post-PTRA renal artery stenosis classification (based on arteriography or duplex scan) was normal in 23, < 60% in 19, and > or = 60% in 10. The cumulative incidence of restenosis from normal to > or = 60% was 13% at 1 year and 19% at 2 years. The cumulative incidence of restenosis from < 60% to > or = 60% was 44% at 1 year and 55% at 2 years. The cumulative incidence of progression from > or = 60% to occlusion was 10% at 2 years. Although 83% of the 12 stented arteries and only 33% of the 40 nonstented arteries were normal immediately after PTRA, after 1 year the stented renal arteries showed a 44% restenosis rate, whereas the nonstented renal arteries showed a 18% restenosis rate (p = 0.087). CONCLUSIONS: Restenosis after PTRA for atherosclerotic disease is relatively common and correlates with the initial anatomic result. Although PTRA with stent placement yields superior immediate technical results, the high early restenosis rate is disturbing.

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PubMed1997

Duplex sonography of lower extremity arteries.

Although indirect noninvasive tests continue to play a role in the evaluation of patients with lower extremity arterial disease, the direct approach of duplex scanning provides both anatomic and physiological information directly from the involved arterial sites. Experience has shown that the results of duplex scanning are comparable with those of arteriography. The addition of color Doppler imaging to standard duplex scanning expedites the examination by helping to identify vessels and localize flow disturbances. However, precise classification of disease severity still requires spectral waveform analysis. Initial screening of patients with duplex scanning can determine the severity of arterial occlusive disease, the location of the lesions, and which interventional techniques are most appropriate. Arteriography can then be reserved for those patients who are being considered for therapeutic interventions. Duplex scanning has become the primary diagnostic test for follow-up of patients after radiological or surgical procedures and should be considered as an essential component of care for patients with infrainguinal bypass grafts. It has also proven to be valuable for intraoperative assessment and the initial evaluation of suspected vascular trauma in the extremities. Finally, new applications such as compression therapy for pseudoaneurysms continue to evolve and expand the role of duplex scanning in the management of patients with vascular problems.

Aneurysm, False↗
PubMed1996

A prospective study of disease progression in patients with atherosclerotic renal artery stenosis.

The natural history of renal artery stenosis (RAS) has been difficult to document because serial arteriography is rarely justified. Duplex scanning is a noninvasive technique that is ideally suited for both screening and follow-up of RAS. In this approach, renal arteries are classified as normal, < 60% stenosis, > or = 60% stenosis, or occluded, and disease progression is defined as a change in the duplex classification. The purpose of this study was to determine the rate of disease progression in atherosclerotic RAS by serial duplex scanning. At least one abnormal renal artery was identified in each of 76 patients being screened for RAS. Of the 152 renal arteries, 20 were excluded (14 prior interventions, 5 occlusions, 1 technically inadequate duplex scan), leaving 132 for the natural history follow-up protocol. The patient group included 36 men and 40 women, with a mean age of 67 years, who were followed for a mean of 32 months (maximum 55 months). The initial status of the 132 renal arteries was normal in 36, < 60% stenosis in 35, and > or = 60% stenosis in 61. The cumulative incidence of progression from normal to > or = 60% RAS was 0% at 1 year, 0% at 2 years, and 8% at 3 years. The cumulative incidence of progression from < 60% to > or = 60% RAS was 30% at 1 year, 44% at 2 years, and 48% at 3 years. All 4 renal arteries that progressed to occlusion had > or = 60% stenoses at the initial visit, and for those arteries with a > or = 60% stenosis, the cumulative incidence of progression to occlusion was 4% at 1 year, 4% at 2 years, and 7% at 3 years. Progression of RAS occurred at an average rate of 7% per year for all categories of baseline disease combined. Progression of atherosclerotic RAS is relatively common, particularly from < 60% to > or = 60% stenosis.

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PubMed1995

The relationship between arm-ankle pressure difference and peak systolic velocity in patients with stenotic lower extremity vein grafts.

The relationship between the measured arm-ankle pressure difference (AAPD), or the ankle/arm index (AAI), and the focal peak systolic velocity (PSV) at stenotic sites of infrainguinal vein grafts has not been determined. We attempted to relate these two parameters. We used Doppler systolic pressures and duplex ultrasonography to study 35 infrainguinal vein bypass grafts followed in a surveillance protocol. The following graft groups were identified: grafts in nondiabetic patients (n = 26), grafts in diabetic patients (n = 9), nonrevised stenotic grafts (n = 14), revised stenotic grafts (n = 14), and normal grafts (n = 7). AAPD and AAI were measured in both lower extremities. Pressure gradients across graft stenoses were indirectly estimated using the modified Bernoulli equation (delta P =4V2). Measured AAPDs and estimated pressure gradients showed moderate correlation in nondiabetic (r = 0.58) and diabetic (r = 0.63) patients. Correlation was fair (r = 0.3) prior to graft revision. There was no correlation (r = 0.1) in the nonrevised stenotic grafts. For individual patients with stenotic grafts who were followed in consecutive visits, the correlation varied from none to good (r range 0.01 to 0.71). We conclude that there is a lack of consistent correlation between the measured AAPD, or AAI, and the estimated stenotic graft pressure gradient. This finding illustrates the limitation of the AAI as a monitoring test to predict failure of stenotic infrainguinal vein grafts.

Ankle↗
PubMed1995

Hemodynamics of stenotic infrainguinal vein grafts: theoretic considerations.

We developed a theoretic model of arterial stenosis to study the relationship between perfusion pressure and regional hemodynamics in stenotic infrainguinal vein grafts in an attempt to identify grafts at high risk for failure. Our model was based on the concept of energy and mass conservation of the flowing blood. We used the modified Bernoulli equation (delta P = 4 delta V2) to calculate the maximum possible intrastenotic peak systolic velocity (PSV) from the systolic blood pressure. PSV was measured by means of duplex ultrasonography in infrainguinal bypasses up to the time of revision (nine grafts) or spontaneous thrombosis (two grafts). We related arm systolic blood pressure, intrastenotic PSV, and prestenotic PSV obtained from duplex examinations conducted prior to graft thrombosis or revision and applied our model to these stenotic vein grafts. Intrastenotic PSV was consistently lower than maximum PSV predicted from the Bernoulli equation. The highest measured intrastenotic PSV of 600 cm/sec would require a minimum perfusion pressure of 144 mm Hg. The lowest measured PSV (20 cm/sec) was considered the minimum "thrombotic threshold velocity." This model predicts that for parabolic profile flow in an 80% diameter-reducing axisymmetric stenosis (96% cross-sectional area reduction), a prestenotic PSV of 20 cm/sec would produce an intrastenotic PSV of 500 cm/sec requiring the equivalent potential energy of 100 mm Hg systolic blood pressure. Our theory implies that in patients with nocturnal hypotension thrombosis of stenotic vein grafts may occur.

Blood Flow Velocity↗
PubMed1995

Hemodynamic parameters of failing infrainguinal bypass grafts.

PURPOSE: To assess the relationship of duplex ultrasound hemodynamic parameters in stenotic vein grafts with events such as graft thrombosis or surgical revisions. PATIENTS AND METHODS: We studied 35 patent infrainguinal bypass grafts that were observed by means of color duplex graft mapping using a surveillance protocol. RESULTS: During the 11.2 month mean follow-up interval, 10 grafts developed complications. Two stenotic grafts (1 already revised) thrombosed spontaneously, and arteriography was obtained on the basis of either clinical indications or a decreased ankle/brachial index of greater than 0.15 on 9 bypasses, leading to 12 procedures (multiple procedures on 2 grafts). The 14 duplex examinations preceding an event showed these bypasses had increased focal peak systolic velocities that ranged from 250 to 600 cm/s and velocity ratios that ranged from 3.4 to 25.0 at the stenotic segment of the graft, anastomosis, or outflow artery. None of the grafts with a stenotic peak systolic velocity less than 250 cm/s or a velocity ratio less than 3.4 thrombosed spontaneously or required revision. CONCLUSION: We conclude that stenotic vein grafts with a focal peak systolic velocity of at least 250 cm/s or a velocity ratio of at least 3.4 are at increased risk for thrombosis or need for revision. Asymptomatic stenotic vein grafts with focal peak systolic velocities and ratios less than the above values may be safely observed without immediate risk for thrombosis.

Adult↗
PubMed1994

Natural history of atherosclerotic renal artery stenosis: a prospective study with duplex ultrasonography.

PURPOSE: Although the prevalence of renal artery stenosis in patients with peripheral arterial disease is in the range of 30% to 40%, the role of renal revascularization in patients without severe hypertension or kidney failure is controversial. Duplex scanning is a noninvasive technique that is ideally suited for screening and follow-up of renal artery disease. The purpose of this study was to document the natural history of renal artery stenosis in patients who were not candidates for immediate renal revascularization. METHODS: Eighty-four patients with at least one abnormal renal artery detected by duplex scanning were recruited from patients being screened for renal artery stenosis. Of the 168 renal artery/kidney sides, 29 were excluded (15 prior interventions, 6 nondiagnostic duplex scans, 8 presumed nonatherosclerotic lesions), leaving 80 patients with 139 sides for the follow-up protocol. Renal arteries were classified as normal, less than 60% stenosis, 60% or greater stenosis, or occluded by use of previously validated criteria. RESULTS: The study group included 36 men and 44 women with a mean age of 66 years who were monitored for a mean interval of 12.7 months. The initial status of the 139 renal arteries was normal in 36, less than 60% stenosis in 35, 60% or greater stenosis in 63, and occluded in 5. Although none of the initially normal renal arteries showed disease progression, the cumulative incidence of progression from less than 60% to 60% or greater renal artery stenosis was 23% +/- 9% at 1 year and 42% +/- 14% at 2 years. All four renal arteries that progressed to occlusion had 60% or greater stenoses at the initial visit, and for those sides with a 60% or greater stenosis, the cumulative incidence of progression to occlusion was 5% +/- 3% at 1 year and 11% +/- 6% at 2 years. The mean decrease in kidney length associated with progression of renal artery stenosis to occlusion was 1.8 cm. CONCLUSIONS: Progression of renal artery stenosis, as defined in this study, occurs at a rate of approximately 20% per year. Progression to occlusion is associated with a marked decrease in kidney length. Whether this natural history can be improved by earlier intervention for renal artery stenosis remains to be determined.

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PubMed1994

Prevalence of carotid and lower extremity arterial disease in patients with renal artery stenosis.

Atherosclerosis is the most common cause of renovascular hypertension secondary to hemodynamically significant stenoses (> 60% diameter reduction). To assess the prevalence of atherosclerosis in the peripheral arteries and carotid bifurcation, we prospectively studied 60 patients who had renal artery stenosis documented by ultrasonic duplex scanning. Disease of the peripheral arterial circulation was assessed by the measurement of the ankle/brachial systolic pressure ratio. To evaluate the extracranial carotid artery, ultrasonic duplex scanning was employed. The prevalence of a 50-100% diameter reducing stenosis in the carotid artery was 46% in patients with a > 60% diameter reducing renal artery stenosis. The prevalence of severe peripheral arterial disease was 73% in those patients with a high grade renal artery lesion. The prevalence of severe disease in the peripheral and carotid arteries was less (50% and 25%, respectively) in patients with renal artery lesions that reduced the diameter of the renal artery less than 60%. The high prevalence of associated lesions in the carotid and peripheral circulation in patients with renovascular disease secondary to atherosclerosis should prompt investigation of these major arteries when renal artery disease is detected. Disease of the carotid and peripheral arteries is a common cause of morbidity and should be treated according to accepted guidelines.

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PubMed1994

Renal atrophy and arterial stenosis. A prospective study with duplex ultrasound.

Renal artery disease is an important cause of both renal failure and hypertension. Duplex ultrasound is a reliable noninvasive method for classifying the severity of renal artery lesions and can be repeated to follow the course of the disease over time. The purpose of this study was to determine the changes in kidney size associated with various degrees of renal artery disease. Serial kidney lengths were measured as part of a prospective duplex ultrasound study of patients with renal artery narrowing. Fifty-four patients (22 men, 32 women; mean age, 65.8 years) with 101 renal artery and kidney sides eligible for follow-up were evaluated at 6-month intervals for an average of 14.4 months (range, 4 to 24 months). No kidneys with renal arteries classified as normal or less than 60% diameter stenosis by duplex criteria were found to have a decrease in length of greater than 1 cm during follow-up. In kidneys with a high-grade renal artery stenosis (> or = 60% diameter reduction), 26% (13 of 49 sides) were found to have a decrease in length of greater than 1 cm. The average decrease in length was 1.9 cm (range, 1.2 to 3.4 cm). By life table analysis, the estimated risk of a decrease in length of greater than 1 cm for kidneys with 60% stenosis or greater was 19% at 1 year. Loss of renal mass, as documented by ultrasound measurement of kidney length, is an important consequence of high-grade renal artery stenosis.

Adult↗
PubMed1993

The role of duplex scanning and arteriography before carotid endarterectomy: a prospective study.

PURPOSE: This study examines the current role of diagnostic tests done before carotid endarterectomy and the need for routine arteriography. METHODS: We prospectively studied vascular surgeons' decision-making over a 29-month period during which 111 carotid arteries in 103 patients were considered for endarterectomy. For each case the surgeon's management plan was recorded after clinical evaluation and review of the duplex scan findings, but before arteriography. This plan was later compared with the patient's ultimate clinical management. RESULTS: Of 111 total cases in this period, 17 were excluded from analysis because arteriography was not done or it was performed before the surgeon's evaluation. Carotid duplex scans were diagnostic in 87 (93%) of the remaining 94 cases. The carotid lesion was incompletely assessed by duplex scanning in seven patients because the disease was not limited to the distal common or proximal internal carotid artery (n = 4); anatomic or pathologic features of the carotid artery interfered with imaging or accurate Doppler assessment (n = 1); or an internal carotid artery occlusion could not be distinguished from a high-grade stenosis (n = 2). When a technically adequate duplex scan showed significant disease of the carotid bifurcation, arteriography contributed information that affected clinical management in only a single case (1%). This patient had a middle cerebral artery occlusion distal to a high-grade carotid bifurcation stenosis. CONCLUSIONS: Clinical assessment and duplex scanning were sufficient for the preoperative evaluation of 93% of the candidates for carotid endarterectomy. Clinical circumstances or atypical duplex scan findings can be used to identify the minority of patients for whom arteriography is necessary. On the basis of this experience, we have developed practical guidelines for the selective use of arteriography before carotid endarterectomy.

Adult↗
PubMed1992

Color Doppler characteristics in normal lower extremity arteries.

The purpose of this study was to determine the normal characteristics of the lower extremity arterial system as seen with color Doppler. A total of 420 arterial segments from the level of the proximal abdominal aorta to the distal tibial and peroneal vessels were examined with a color ultrasound scanner in 10 normal volunteers. Each arterial segment was examined for the presence of triphasic flow, wall irregularities, calcification, bruits, collaterals, and post-stenotic flow patterns. Standard duplex spectral waveform data were also obtained at each site. As expected, triphasic flow was present and detected by color Doppler in the majority of arterial segments. Color patterns suggesting the presence of bruits, collaterals, or post-stenotic flow were absent in all cases.

Adult↗
PubMed1992

Color Doppler imaging of infrainguinal arterial occlusive disease.

Few reports in the literature validate the use of color Doppler imaging (CDI) for the evaluation of lower extremity arterial occlusive disease, particularly in the tibial and peroneal arteries. This prospective, blinded study compares CDI to arteriography to address the following questions: (1) how well does CDI visualize arterial segments, including those below the knee? and (2) can CDI alone accurately classify the degree of occlusive disease? Twenty-nine men undergoing arteriography before a lower extremity arterial reconstructive procedure were studied with a color ultrasound scanner from the level of the inguinal ligament to the ankle. Color images were examined for the presence or absence of triphasic flow, poststenotic turbulence, color bruits, and collateral vessels. Among 636 arterial segments adequately visualized by arteriography, > or = 90% were identified with color Doppler imaging, including the tibial and peroneal arteries. With color criteria only, specificity was > or = 92% for distinguishing < 50% from > = 50% lesions and > or = 93% for differentiating patent from occluded arteries. Sensitivity for detecting an occlusion was > or = 97% in the superficial femoral (SFA) and popliteal arteries and 83% in the tibial vessels. For identifying a > or = 50% stenosis, sensitivity was > or = 85% in the SFA and popliteal arteries but only 79% and 86% in the posterior and anterior tibial arteries, respectively. CDI reliably identifies vessel location from the level of the groin to the ankle. For the detection of occlusions, CDI is an accurate screening tool in the SFA and popliteal arteries but is less accurate in the tibial vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Intraabdominal paraanastomotic aneurysms after aortic bypass grafting.

Although the reported incidence of intraabdominal paraanastomotic aneurysms after abdominal aortic bypass grafting ranges from 1% to 15%, the true incidence is unknown because few studies have used routine, serial radiographic or sonographic imaging studies. Since July 1, 1988, we have used yearly abdominal sonography examinations to monitor our patients with aortic grafts. In the first 33 months we studied 138 patients. Medical records of 111 of these were available for review and form the basis of this report. Eleven patients (10%) were found to have intraabdominal paraanastomotic aneurysms ranging in overall size from 4.1 to 6.2 cm (mean, 5.0 +/- 0.7 cm). The mean time between operation and detection of an aneurysm was 144 +/- 101 months (range, 8 to 336 months). Three paraanastomotic aneurysms occurred within 3 years of operation, and the remaining eight occurred late (7 to 28 years). By life-table analysis, the incidence of paraanastomotic aneurysms was 27% at 15 years. Paraanastomotic aneurysms were classified as either pseudoaneurysms (presumed disruption of the anastomotic suture line, n = 7) or as true aneurysms (widening of the adjacent aorta, n = 4). True aneurysms occurred only after repair of an abdominal aortic aneurysm, whereas pseudoaneurysms were more frequent after bypass for occlusive disease. The finding of paraanastomotic aneurysms in 10% of our patients supports the use of yearly sonography for routine follow-up after aortic grafting.

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