Stephen H. Smyth

Contrast-induced nephrotoxicity: The effects of vasodilator therapy☆

The increasingly frequent use of contrast-enhanced imaging for diagnosis or intervention in patients with peripheral vascular disease has generated concern about the incidence and avoidance of contrast-induced nephrotoxicity (CIN). In this prospective study, we sought to identify those patients at greater risk of developing CIN and to evaluate the efficacy of vasodilator therapy with dopamine in limiting this complication. Baseline serum creatinine (Cr) concentrations were obtained on admission and daily for up to 72 hr after angiography in 222 patients undergoing 232 angiographic procedures. The preangiographic treatment was varied at 2-month intervals for 1 year. All patients received an intravenous infusion of 5% dextrose and 0.45% normal saline at a rate of 75 to 125 ml/hr. During the first interval patients received 12.5 g of 25% mannitol immediately prior to their contrast load, in addition to intravenous fluids. During the next 2-month period the patients were given renal dose dopamine intravenously (3 micrograms/kg/min) commencing the evening before angiography and continued to the next morning. During the latter half of the study the treatment regimens were modified so that the use of mannitol was restricted to patients with diabetes mellitus and dopamine to patients with serum creatinine concentrations of > or = 2 mg/dl. Postangiographic elevation in Cr occurred in 2, 10.4, and 62% of studies in patients with baseline creatinine levels of < or = 1.2 mg/dl, 1.3 to 1.9 mg/dl, and > or = 2.0 mg/dl, respectively. None of the patients receiving dopamine experienced an elevation in creatinine. There was no statistical correlation between age, diabetes, or medication with calcium channel blockers and CIN.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary Embolism Following Hemodialysis Access Thrombolysis/Thrombectomy

PURPOSE The increased use of thrombectomy with deliberate pulmonary embolization of thrombus following initial thrombolysis for occluded hemodialysis fistulas prompted the authors to measure the prevalence of pulmonary embolism (PE) due to the procedure. PATIENTS AND METHODS Thirty-one patients with 43 acutely thrombosed polytetrafluoroethylene hemodialysis fistulas were treated with thrombolysis/thrombectomy. Perfusion lung scans were obtained in 22 patients. Patients were also continuously monitored for clinical signs or symptoms of PE. RESULTS Perfusion scans were interpreted as consistent with PE in 59% of those studied, but no clinical signs or symptoms were present in 41 of the 43 cases (95%). However, two patients developed both signs and symptoms of acute PE in the postprocedural period and died. One had underlying pulmonary disease and had undergone thrombectomy before. The other had chronic heart disease. CONCLUSION Thrombolysis/thrombectomy is usually safe and effective, even though many patients develop subclinical PE. The authors urge extreme caution in patients who have underlying pulmonary or cardiac disease and/or have undergone the procedure before.

Abdominal wall hernias in patients with abdominal aortic aneurysmal versus aortoiliac occlusive disease

BACKGROUND This study was undertaken to determine the incidence of ventral incisional hernias (VIHs) and inguinal hernias (IHs) in patients with abdominal aortic aneurysmal (AAA) versus those with aortoiliac occlusive disease (AIOD). PATIENTS AND METHODS The medical records of 193 patients (128 with AAA and 65 with AIOD) who had undergone elective aortic reconstruction were reviewed to determine the number and location of abdominal wall hernias (AWHs). RESULTS Forty-one AWHs (28 IHs and 13 VIHs) were detected in patients with AAA compared to 13 (11 IHs and 2 VIHs) in patients with AIOD. There was a significantly greater incidence of VIHs in patients with AAA versus patients with AIOD (10% versus 3%, P < 0.05) and recurrent AWHs (28% versus 19%, P < 0.01), but not of IHs (22% versus 17%). CONCLUSION Patients with AAA have a higher incidence of VIHs and recurrent AWHs--without a corresponding increase in patient-related risk factors--than patients without aneurysm, suggesting that as yet unidentified etiologic factors may contribute to the development of AWHs in these patients.

CT Findings of Rupture, Impending Rupture, and Contained Rupture of Abdominal Aortic Aneurysms

OBJECTIVE With the increasing use of cross-sectional imaging for a variety of medical and surgical conditions affecting the abdomen and pelvis, familiarity with the imaging features of aneurysm rupture--and the findings suspicious for impending or contained aneurysm rupture--is crucial for all radiologists. This pictorial essay will review the imaging findings of rupture of abdominal aortic aneurysms and of complicated aneurysms. CONCLUSION Prompt detection of abdominal aortic aneurysm rupture or impending rupture is critical because emergent surgery may be required and patient survival may be at stake.

Bradyarrhythmias During Use of the AngioJet System

The AngioJet system is an effective thrombectomy device, but it may cause chest discomfort and provoke bradyarrhythmias that range from mild bradycardia to asystole. The cause of AngioJet-induced bradyarrhythmia is unknown, although several hypotheses have attempted to explain the phenomenon. Herein several cases will be described, followed by a review of the relevant literature. The literature review suggests that the cause may be related to the effects of the hydrodynamic jets on stretch-activated receptors present on the vascular endothelium, and that pretreatment with gadolinium or streptomycin might prevent activation of these receptors.

Incidence and histologic characteristics of blebs in patients with abdominal aortic aneurysms

PURPOSE Aortic blebs-focal outpouchings within aortic aneurysms-may contribute to their eventual rupture. In this study we determine the incidence of aortic blebs and describe their microscopic features. METHODS Computed tomographic scans of the abdominal aorta were obtained in 188 patients with aortic diameters measuring > or = 3 cm and were independently evaluated by a radiologist. The number and location of blebs were recorded, and each was measured with calipers. Sixteen blebs, with an adjacent uninvolved aneurysmal segment of aorta, and tissue from two patients with ruptured aneurysms were examined by light microscopy and immunohistochemical analysis. Specimens from six blebs and five aneurysms were examined for alpha 1 (I) procollagen messenger RNA by in situ hybridization. RESULTS Twenty blebs, ranging in size from 5 to 30 mm (mean, 12 +/- 7 mm), were detected in 11% (20 of 188) of computed tomographic scans. Blebs were observed in 10% (11 of 111) of patients with aortic diameters between 3.0 and 4.9 cm, 10% (6 of 61) of patients with aneurysms between 5.0 and 6.9 cm, and 19% (3 of 16) of patients with aortic diameters > or = 7 cm. Histologically, the major difference between the aneurysmal aortic wall and blebs was found in the media. In aneurysmal aortas, the media consisted of multiple layers of fragmented elastic lamellae, whereas the number of elastic tissue elements along the circumference of the blebs progressively decreased; only a few isolated fragments of elastic tissue were present at the apices. Histologic evidence of rupture was evident in two specimens. A chronic inflammatory cell infiltrate composed of T and B lymphocytes, plasma cells, and macrophages, common to both the aneurysmal and the blebs, was most prominent in the adventitia of aneurysmal tissue, but involved both the media and adventitia of the blebs. In situ hybridization demonstrated the presence of alpha 1 (I) procollagen messenger RNA in four of the five aneurysm segments that were evaluated, compared with only one of six blebs. CONCLUSIONS Blebs were discovered in aneurysms of all sizes; their frequency appeared to be unrelated to aneurysm size. The presence of inflammatory cell infiltrates and absence of alpha 1 (I) procollagen messenger RNA in five of six blebs suggest that a local imbalance of matrix degradation and repair plays a role in the cause of these lesions. Attenuation of the aortic wall accompanying the formation of blebs may predispose these sites to rupture.

Application of computed tomography for surveillance of aortic grafts.

BACKGROUND This study was undertaken to assess the application of computed tomography (CT) for surveillance of aortic grafts. METHODS Demographics, operative technique, and graft type and size at the time of implantation of aortic grafts in 178 patients were recorded. CT measurements of graft diameters were made with calipers. Data were analyzed by analysis of variance, multiple regression, and chi-squared methods. RESULTS One hundred twenty-eight (72%) bifurcated grafts and 50 (28%) tube grafts were placed for aneurysmal disease (49%), aortoiliac occlusive disease (47%), ruptured aneurysm (2.3%), anastomotic aneurysm (1%), and graft aneurysm (0.6%). Mean implant time was 43.3 +/- 3.2 months. A total of 143 Dacron prostheses (74 woven, 69 knitted) and 35 polytetrafluoroethylene prostheses were placed. Mean percentage dilation was 49.2 +/- 4.0 for knitted prostheses, 28.5 +/- 3.0 for woven prostheses, and 20.6 +/- 1.9 for polytetrafluoroethylene prostheses compared with the graft implant size. A significant correlation was seen between graft dilation (more than 50%) and graft construction with knitted prostheses (p < 0.01, Tukeys range test). Complications detected by CT occurred in 24 (13.5%) patients including supragraft aneurysms (seven), distal anastomotic aneurysms (five), proximal anastomotic aneurysms (three), graft infections (two), perigraft fluid collections (two), graft aneurysm with thrombus and distal embolization (two), and nonvascular complications (three). CONCLUSIONS CT is a useful modality for postoperative imaging of aortic prostheses. Routine surveillance may detect complications before they become clinically apparent.

Prospective Comparison of Plain Abdominal Radiography with Conventional and Digital Renal Tomography in Assessing Renal Extracorporeal Shock Wave Lithotripsy Patients

Most publications citing the effectiveness of renal extracorporeal shock wave lithotripsy have used plain abdominal radiography to assess residual calculi after treatment. We compared radiologist sensitivity and specificity in the detection of calculi on plain abdominal radiographs versus conventional film-screen and digital renal tomograms in extracorporeal shock wave lithotripsy patients. Of the patients 50 were imaged before and within 24 hours after lithotripsy. Six radiologists evaluated the resultant 300 studies for the presence and location of calculi. The mean sensitivity for digital tomograms was 83% for pre-lithotripsy and post-lithotripsy studies, which was significantly higher than for plain abdominal radiography and conventional tomography after lithotripsy. However, there were significantly more false positive stone diagnoses associated with digital tomogram interpretation. Signal detection analysis verified the over-all superiority of digital tomography for post-extracorporeal shock wave lithotripsy imaging. Calculus detection by conventional and digital tomography is superior to detection by plain abdominal radiography. However, because we did not perform delayed imaging, it is not possible to say what impact digital tomography might have on the management of extracorporeal shock wave lithotripsy patients.

Intravascular Papillary Endothelial Hyperplasia Sonographic Appearance With Histopathologic Correlation

Intravascular papillary endothelial hyperplasia (IPEH) is a benign vascular proliferative process characterized by papillary proliferation of endothelial cells located within a vascular lumen. The lesions occur most commonly in the extremities and in the head and neck region. 1,2 Reports of the imaging findings of these masses are scarce. We report a rare case of IPEH occurring in a dorsal wrist vein with demonstration of the sonographic appearance and pathologic correlation.

Reactivation of Herpes Zoster after Liver Biopsy

A patient developed reactivation of herpes zoster infection (shingles) after a routine liver biopsy. Reactivation of herpes is often related to trauma. This entity should be considered when patients report postbiopsy pain inappropriate to the procedure. If the typical rash of shingles develops, antiviral therapy should be considered.