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Biomedical subjects

David P Slovut

Publications and source records attributed to David P Slovut.

9 recordsLinked to original sources
PubMed2006

Correlation between noninvasive and endovascular Doppler in patients with atherosclerotic renal artery stenosis: a pilot study.

Considerable interest exists in using endovascular techniques for assessing the renal circulation. The vasomotor response of the renal circulation in patients with hypertension and severe atherosclerotic renal artery stenosis was evaluated. Sixteen patients (5 men and 11 women) with a mean age of 73.2+/-7.1 years (range, 59-82 years) underwent noninvasive renal duplex ultrasonography and endovascular flow wire evaluation. The flow wire was positioned in the main renal artery distal to the stenosis and used to examine the reactivity of the renal circulation in response to intra-arterial papaverine before and after percutaneous revascularization. Resistive index was computed as (MPV - EDV)/MPV, where MPV is the maximum peak velocity and EDV is the end-diastolic velocity. Renal flow reserve was defined as the ratio of peak hyperemic response to baseline flow. Intervention was technically successful in 18/18 arteries. Heart rate (69+/-11 vs. 65+/-10 beats/min; P=NS) and systolic blood pressure (168+/-19 vs. 163+/-24 mm Hg; P=NS) remained constant following injection of intrarenal papaverine, while diastolic blood pressure decreased (77+/-13 vs. 65+/-11 mm Hg; P<0.006). Papaverine injection resulted in significant increases in average peak velocity (APV; 148% of baseline; P=0.0003), MPV (146% of baseline; P=0.001), and EDV (161% of baseline; P=0.0026), but had no effect on the endovascular resistive index (0.81+/-0.12 vs. 0.84+/-0.08; P=NS). Renal artery stenting produced no effect on APV or EDV, but a small increase in MPV (123% of baseline; P<0.05). In contrast, renal stenting resulted in a significant increase in the endovascular resistive index (0.77+/-012 vs. 0.84+/-0.08; P=0.003), pulsatility index (1.84+/-0.61 vs. 2.23+/-0.70; P<0.014), and renal flow reserve (1.49+/-0.44 vs. 1.86+/-0.73; P<0.0071). A correlation was found between the noninvasive and endovascular measures diastolic/systolic ratio (r=0.73; P<0.0009) and resistive index (r=0.63; P<0.0053). Patients with atherosclerotic renal artery stenosis have preserved vasomotor response to papaverine, as well as marked increases in renal flow and resistive index following successful renal artery stenting. Endovascular flow wire measurements are safe, easy to perform, and correlate well with noninvasive Doppler measurements.

Aged↗
PubMed2005

Fibromuscular Dysplasia.

The most common clinical manifestations of fibromuscular dysplasia (FMD) are hypertension due to renal artery involvement and transient ischemic attack or stroke due to carotid or vertebral artery involvement. Patients with renal artery FMD and hypertension should undergo primary angioplasty with the goal of curing the hypertension. If the blood pressure fails to normalize following angioplasty, the physician should institute antihypertensive medications according to the recommendations of the Joint National Committee on the Prevention, Detection, and Treatment of High Blood Pressure VII. In patients with cerebrovascular FMD, antiplatelet agents represent the cornerstone of therapy. Percutaneous angioplasty has emerged as the preferred treatment for symptomatic cerebrovascular FMD.

Journal Article↗
PubMed2005

Endovascular treatment of an occluded axillofemoral bypass graft.

Unsuspected subclavian or axillary disease may cause failure of axillofemoral bypass grafts. A 52-year-old woman who underwent left axillofemoral bypass grafting 5 years ago presented with 24 h of left foot pain. Routine duplex ultrasonography 2 months previously demonstrated velocities throughout the graft > 80 cm/s. Emergent angiography revealed thrombotic occlusion of the axillofemoral bypass graft. Both rheolytic thrombectomy and pulse spray thrombolysis using tissue plasminogen activator were used to restore graft patency. Arterial pressure waveform and pressure remained damped throughout the graft; a 50 mmHg gradient was found from the descending thoracic aorta to the mid-left subclavian artery. Angiography revealed a 70% diameter stenosis at the origin of the left subclavian artery. Following balloon angioplasty and stent placement, the pressure gradient was eliminated. In conclusion, careful evaluation of arterial inflow to bypass grafts is critical for ensuring long-term graft patency.

Angiography, Digital Subtraction↗
PubMed2004

Increased vascular sensitivity and connexin43 expression after sympathetic denervation.

OBJECTIVE: Following denervation, arteries demonstrate a heightened sensitivity to alpha-adrenergic agonists and increased oscillatory contractions that may partly result from increased gap junction expression. Hence, we wanted to study the effect of sympathetic denervation on connexin43 (Cx43) expression and agonist-induced contractility in the vascular smooth muscle (VSM). METHODS: Effects of denervation with reserpine (3 mg/kg/day, i.p.) or topical 5% phenol-glycerol on VSM contractions and expression of the gap junction Cx43 mRNA by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting for Cx43 protein were examined. Wistar-Kyoto (WKY) rat tail arteries were exposed to norepinephrine (NE) (10(-9)-10(-5) M). Reactivity was also examined in the carotid arteries and thoracic aortas from Cx43 heterozygote deficient (KO) mice. RESULTS: The concentration for NE-induced contraction was lower in reserpine- and phenol-treated vessels than controls (p<0.05). NE-induced oscillatory activity (OA) was seen in 5/5 reserpine- and 5/8 phenol-treated vessels vs. 0/12 controls (p<0.05). Spontaneous OA was observed more frequently in carotid and aortic rings from WT than Cx43 KO rings. Cumulative OA in response to alpha-adrenergic stimulation was significantly greater in WT carotid (429+/-101 vs. 128+/-7 mN s, p<0.05) and aortic rings (337+/-85 vs. 134+/-11 mN s, p<0.05) than in Cx43 KO rings. Following denervation, RT-PCR showed significantly increased levels of Cx43 mRNA (p<0.05). Western blot analysis revealed near doubling of Cx43 protein (p<0.05). CONCLUSION: We conclude that sympathetic denervation results in increased expression of Cx43, which in turn, contributes to increased spontaneous and agonist-induced OA in VSM.

Animals↗
PubMed2004

Aortic aneurysm repair with endovascular grafts: developing a graft surveillance program.

The objective of this study was to describe the development of a comprehensive surveillance program for monitoring the long-term follow-up of endoluminal stent graft (ELG) patients. Despite high procedural success rates, ELG patients remain at ongoing risk for aneurysm sac expansion, rupture, and other adverse events that make long-term surveillance imperative. As they perform more ELG, practitioners face increased logistical difficulty performing appropriate patient follow-up. A computer-based data ELG registry was created using Epi Info, a program developed by the Centers for Disease Control and Prevention that enables users to design a data entry form, enter data, and perform statistical analyses. The database has been used to track 259 patients (214 men and 45 women) who underwent ELG between November 1999 and October 2003. One-year follow-up was available for 182 patients, 2-year follow-up for 104 patients, and 3-year surveillance data for 40 patients, which represent follow-up rates of 89.6%, 78.8%, and 61.5%, respectively. There were 25 late deaths. The Kaplan-Meier estimate for 1-year survival was 92.5%. Twenty-one patients underwent 24 secondary angiographic procedures at a mean 8.6 +/- 10.3 months (range, 1-37.6) after stent-graft repair. No mortality was observed in association with a secondary intervention. There were no late conversions to open aneurysm repair. The Kaplan-Meier estimate for freedom from secondary intervention for all patients at 1 year was 91.0%. A computer-based registry facilitates appropriate and timely patient follow-up and may improve the long-term outcome from ELG.

Aged↗
PubMed2003

Endovascular therapies for vascular disease.

Endovascular techniques including angioplasty, stenting, and endoluminal stent grafts represent important therapeutic options for the treatment of vascular disease. Technologic advances have allowed for the treatment of aneurysmal disease as well as extra-cranial carotid disease that previously required surgical methods. The success of various endovascular therapies varies based on anatomic location and extent of disease. The clinical results in different arterial segments are increasingly recognized in the published literature. The aortoiliac arterial bed appears to respond most favorably, with less favorable results observed in the infra-inguinal and infrapopliteal locations. There is increasing evidence that stent-supported carotid angioplasty using cerebral protection will play an important future role in the treatment of carotid artery stenosis. Less invasive techniques to treat abdominal aortic aneurysms with endoluminal stent grafts have dramatically changed the available therapeutic options. Improved devices and delivery systems will likely increase the number of patients who can be successfully treated in this manner. The evolution of endovascular therapies will continue to change the way we treat vascular disease.

Aneurysm↗
PubMed2003

Endoluminal AAA repair using intravascular ultrasound for graft planning and deployment: a 2-year community-based experience.

PURPOSE: To examine the effectiveness of intravascular ultrasound (IVUS) and digital subtraction angiography (DSA) for preoperative planning and intraoperative deployment of stent-grafts to treat abdominal aortic aneurysms. METHODS: One hundred seventy patients (143 men; mean age 73.6+/-7.2 years, range 51-89) underwent successful DSA and IVUS to determine suitability for stent-graft repair. Patients subsequently received the AneuRx (n=157) or Ancure (n=13) device; intraprocedural IVUS was used to survey the proximal endograft for proper apposition to the aortic wall. RESULTS: Reliable preoperative IVUS measurements were obtained in all patients. Plaque morphology was assessed in 140 (82.3%) aortic necks; in 36 (25.7%), preoperative IVUS showed high-grade atherosclerotic plaque in the nonaneurysmal abdominal aortic neck. The procedure was successful in 168 (98.8%) cases (1 [0.6%] acute conversion and 1 access failure). There were 2 (1.2%) periprocedural deaths related to bowel ischemia. Four (2.3%) patients developed graft occlusion/kinking and 2 (1.2%) developed renal failure requiring dialysis within 30 days. Multivariate logistic regression analysis revealed that female gender (p=0.0247), a short nonaneurysmal aortic neck (p=0.0185), and presence of high-grade atherosclerotic plaque (p=0.0185) correlated with major acute complications. Over a mean 10.4-month follow-up (range 1-25), 11 patients died of unrelated causes; there was no known AAA rupture or device failure. The Kaplan-Meier estimate of survival at 1 year was 91.0%+/-2.8%. Sixteen (9.4%) patients underwent 17 secondary procedures for endoleak or graft limb occlusion at a mean 5.4 months after stent-graft repair (freedom from secondary intervention at 1 year 86.5%+/-3.2%). CONCLUSIONS: Our findings suggest that IVUS may identify patients at increased risk of major adverse complications following endovascular repair. The combination of IVUS and DSA for endoluminal stent-graft planning and placement provides excellent short- and mid-term patient outcomes.

Aged↗