Lukas C. van Dijk

Inter-observer variability in the angiographic assessment of renal artery stenosis

OBJECTIVEnTo assess inter-observer agreement in the interpretation of renal angiograms.nnnDESIGNnComparison of the assessment of renal angiograms by three experienced radiologists, who evaluated the number of renal arteries and the presence, location, aspect and severity of a renal artery stenosis.nnnSETTINGnGeneral hospital and university hospital serving urban and rural populations.nnnPATIENTSnPatients with difficult-to-treat hypertension referred for diagnostic work-up; 312 angiograms with the intra-arterial digital subtraction technique were obtained from 289 consecutive patients.nnnMAIN OUTCOME MEASURESnInter-observer agreement was tested for the following parameters: number of arteries per kidney, presence of stenosis, location of stenosis (truncal, ostial), aspect of stenosis (concentric, eccentric, post-stenotic dilatation), severity of stenosis (reduction of lumen diameter in categories of 30%, 40%, etc. to 100%), and overall quality of the angiographic images. Kappa (kappa) values and weighted kappa between the three pairs of radiologists were used as estimates of inter-observer agreementnnnRESULTSnAgreement about the number of renal arteries was reasonable (kappa = 0.50-0.72), as was agreement about the presence of stenosis (kappa = 0.68-0.86). Agreement about stenosis location and aspect was poor (kappa = 0.26-0.47 and kappa = 0.15-0.26, respectively). There was general agreement about the severity of stenosis (weighted kappa = 0.65-0.70), but it was not possible to distinguish between 50 and 60% stenosis or between 60 and 70% stenosis (kappa < 0.40). No correlation was found between agreement on severity of stenosis and the quality of the images.nnnCONCLUSIONSnIt is not realistic to make statements about what degree of renal artery stenosis is clinically significant, as long as the intra-arterial angiogram with digital subtraction remains the gold standard. It is likewise risky to rely too strongly on stenosis morphology as visualized by renal angiography in choosing between balloon angioplasty and stent deployment.

Endovascular versus Conventional Open Repair of Acute Abdominal Aortic Aneurysm: Feasibility and Preliminary Results

PURPOSEnTo evaluate the feasibility of endovascular treatment of acute abdominal aortic aneurysm (AAA) with commercially prepared bifurcated systems.nnnMETHODSnFrom January through July 2001, 22 patients (17 men; mean age 73.6 years, range 59-89) were referred with an acute (symptomatic/ruptured) AAA. Six patients were treated with emergent open surgery because of hemodynamic instability, but the other 16 patients underwent computed tomographic angiography with multidirectional reconstruction. Six (27%) aneurysms were suitable for endovascular repair (EVR) and were successfully treated. Procedural variables, morbidity, and mortality were compared between the EVR group and 6 patients of equivalent hemodynamic status from among the conventionally treated patients.nnnRESULTSnThere was no mortality in either group. The median aneurysm diameter in the EVR group was 63 mm (range 48-84) versus 80 mm (45-82) in the matched surgically treated AAAs (p=0.628). Procedural duration was 193 minutes (150-265) for the EVR group compared to 203 minutes (130-270) for the matched group (p=0.630). Median blood loss was significantly less (p=0.010) in the EVR group (125 versus 3400 mL). Median length of stay (LOS) in intensive care was 8 hours (0-21) versus 62 hours (48-112) for the surgical group (p=0.004). Hospital LOS was significantly reduced (p=0.024) for the EVR patients (7.5 [2-16] versus 15.5 [10-34] days).nnnCONCLUSIONSnEndovascular treatment of acute aneurysm is feasible, and preliminary results are promising.

Embolization with the Amplatzer Vascular Plug in TIPS Patients

Vessel embolization can be a valuable adjunct procedure in transjugular intrahepatic portosystemic shunt (TIPS). During the creation of a TIPS, embolization of portal vein collaterals supplying esophageal varices may lower the risk of secondary rebleeding. And after creation of a TIPS, closure of the TIPS itself may be indicated if the resulting hepatic encephalopathy severely impairs mental functioning. The Amplatzer Vascular Plug (AVP; AGA Medical, Golden Valley, MN) is well suited for embolization of large-diameter vessels and has been employed in a variety of vascular lesions including congenital arteriovenous shunts. Here we describe the use of the AVP in the context of TIPS to embolize portal vein collaterals (nxa0=xa08) or to occlude the TIPS (nxa0=xa02).

Accurate assessment of abdominal aortic aneurysm with intravascular ultrasound scanning: Validation with computed tomographic angiography☆☆☆★

PURPOSEnThe purpose of this study was to assess the accuracy of intravascular ultrasound (IVUS) parameters of abdominal aortic aneurysm, used for endovascular grafting, in comparison with computed tomographic angiography (CTA).nnnMETHODSnThis study was designed as a descriptive study. Between March 1997 and March 1998, 16 patients with abdominal aortic aneurysms were studied with angiography, IVUS (12.5 MHz), and CTA. The length of the aneurysm and the length and lumen diameter of the proximal and distal neck obtained with IVUS were compared with the data obtained with CTA. The measurements with IVUS were repeated by a second observer to assess the reproducibility. Tomographic IVUS images were reconstructed into a longitudinal format.nnnRESULTSnIVUS results identified 31 of 32 renal arteries and four of five accessory renal arteries. A comparison of the length measurements of the aneurysm and the proximal and distal neck obtained with IVUS and CTA revealed a correlation of 0.99 (P <.001), with a coefficient of variation of 9%. IVUS results tended to underestimate the length as compared with the CTA results (0.48 +/- 0.52 cm; P <.001). A comparison of the lumen diameter measurements of the proximal and distal neck derived from IVUS and CTA showed a correlation of 0.93 (P <.001), with a coefficient of variation of 9%. IVUS results tended to underestimate aneurysm neck diameter as compared with CTA results (0.68 +/- 1.76 mm; P =.006). Interobserver agreement of IVUS length and diameter measurements showed a good correlation (r = 1.0; P <.001), with coefficients of variation of 3% and 2%, respectively, and no significant differences (0.0 +/- 0.16 cm and 0.06 +/- 0.36 mm, respectively). The longitudinal IVUS images displayed the important vascular structures and improved the spatial insight in aneurysmal anatomy.nnnCONCLUSIONnIntravascular ultrasound scanning results provided accurate and reproducible measurements of abdominal aortic aneurysm. The longitudinal reconstruction of IVUS images provided additional knowledge on the anatomy of the aneurysm and its proximal and distal neck.

Endoscopic aneurysm sac fenestration as a treatment option for growing aneurysms due to type II endoleak or endotension

Purpose: To evaluate endoscopic fenestration as a treatment option for growing aneurysm due to a type II endoleak or endotension after endovascular aneurysm repair (EVAR). Methods: Eight patients (7 men; median age 69 years, range 55–79) who underwent “successful” EVAR were diagnosed with a growing aneurysm due to a type II endoleak (n = 4) or endotension (n=4). Surgical intervention consisted of endoscopic fenestration of the sac and removal of all the thrombus material, preceded by clipping of the inferior mesenteric and all lumbar arteries in cases of endoleak. Fluid samples from the fenestrated aneurysm sac were analyzed for the presence of microorganisms and fibrin degradation products (FDP) and/or D-dimers. Results: The median duration of operation was 220 minutes (range 111–333). There was no perioperative mortality. In one patient, the endoscopic procedure was converted to an open fenestration procedure. Seven patients had uncomplicated follow-up and a clear decrease in the diameter of the sac; one patient was converted to open repair owing to continued sac growth despite fenestration. Bacterial cultures were negative in all patients, but high levels of FDP and/or D-dimers were found in all available samples, indicating continued fibrinolysis. Conclusion: Endoscopic fenestration, with or without endoscopic clipping of all side branches, seems to be an effective, reliable and minimally invasive treatment option for patients with a growing aneurysm due to type II endoleak or endotension. The high levels of FDP and/or D-dimers in the aneurysm sac are suggestive of hyperfibrinolysis, which may play an important role in aneurysm growth after EVAR.

Endovascular Repair of an Extracranial Internal Carotid Artery Aneurysm Complicated by Heparin-Induced Thrombocytopenia and Thrombosis

Purpose: To report the endovascular treatment of a symptomatic extracranial internal carotid artery (ICA) aneurysm that was complicated by heparin-induced thrombocytopenia and thrombosis. Methods and Results: After undergoing a coronary artery bypass graft procedure, a patient was diagnosed with a symptomatic, 3.5-cm ICA aneurysm by computed tomography and angiography. Via a semiclosed access, an Enduring vascular graft was inserted under controlled back bleeding from the ICA. The patient was recovering uneventfully when routine duplex scanning on the fifth postoperative day suggested multiple thrombi within the graft, which was confirmed by arteriography. Thrombectomy and local fibrinolysis were performed; however, the graft occluded the next day without causing neurological symptoms. Heparin-induced thrombocytopenia was diagnosed by enzyme-linked immunosorbent assay. Conclusions: Endovascular repair of high cervical extracranial ICA aneurysms is feasible, and protection against intracerebral embolization can be achieved using a semiclosed technique with controlled back bleeding from the ICA during endograft deployment. However, multiple thrombi or thrombotic occlusion during the postoperative period, particularly in a patient already sensitized to heparin, should direct attention toward possible heparin-induced thrombocytopenia.

Intravascular Ultrasound Evidence for Coarctation Causing Symptomatic Renal Artery Stenosis

BACKGROUNDnA recent study of human cadaveric renal arteries revealed that renal artery narrowing could be due not only to atherosclerotic plaque compensated for by adaptive remodeling, but also to hitherto undescribed focal narrowing of an otherwise normal renal arterial wall (ie, coarctation). The present study investigated whether vessel coarctation could be identified in patients with symptomatic renal artery stenosis (RAS).nnnMETHODS AND RESULTSnConsecutive symptomatic patients with angiographically proven atherosclerotic RAS who were referred for stent placement were studied by 30-MHz intravascular ultrasound before intervention (n=18) or after predilatation (n=18). Analysis included assessment of the media-bounded area and plaque area (PLA) at the most stenotic site and at a distal reference site (most distal cross-section in the main renal artery with normal appearance). Coarctation was considered present whenever the target/reference media-bounded area was </=85%. Before intervention, coarctation was observed in 9 of 18 patients and adaptive remodeling in 9 of 18 patients. Coarctation lesions had a significantly smaller PLA than adaptive remodeled lesions (P=0.001). Similarly, despite predilatation, coarctation was seen in 8 of 18 patients who had significantly smaller PLAs (P=0. 008) when compared with those patients who had adaptive remodeled lesions. No differences in severity of RAS or angiographic or clinical parameters were observed.nnnCONCLUSIONSnLow-plaque coarctation may cause a considerable proportion of symptomatic RAS, which is angiographically and clinically indistinguishable from plaque-rich RAS.

Comparison of catecholamine hormone release in patients undergoing carotid artery stenting or carotid endarterectomy.

Purpose: To investigate the pattern of catecholamine response in patients undergoing carotid endarterectomy (CEA) or carotid artery stenting (CAS). Methods: Adrenaline, noradrenaline, and renin levels were measured at 5 time points in 12 patients undergoing 13 CEAs (1 bilateral) and 13 patients undergoing unilateral CAS. Arterial blood samples were taken at the following time points: (1) after induction in CEA patients or 5 minutes following first contrast injection in CAS patients, (2) 5 minutes following ICA clamp release in surgical patients or deflation of the balloon in the CAS cohort, (3) 60 minutes following ICA clamp release in surgical patients or deflation of the balloon in the CAS cohort, and (4) 24 hours following the procedure. Intraoperative blood pressure and heart rate were recorded using radial arterial monitoring. Changes in adrenaline, noradrenaline, and renin levels are expressed as ratios versus baseline. Results: Patterns of adrenaline and noradrenaline release were significantly different in patients undergoing CAS and CEA, with much higher and more variable surges of adrenaline and noradrenaline occurring in CEA patients. Adrenaline and noradrenaline levels increased significantly over baseline following carotid artery clamping in patients undergoing CEA (noradrenaline ratio before clamping: 1.54±1.25, 24 hours after unclamping: 8.38±16.35 [p<0.001]; adrenaline ratio before clamping: 1.12±0.49, 60 minutes after unclamping: 17.59± 19.14 [p<0.001]). Conversely, in patients undergoing CAS, catecholamine levels remained unchanged (noradrenaline ratio before dilation: 0.96±0.23, 24 hours after the procedure: 0.92±0.32 [p = NS]; adrenaline ratio before dilation: 0.83±0.33, 60 minutes after balloon deflation: 0.56±0.32 [p = NS]). Conclusions: CAS is associated with a significantly less marked catecholamine response than CEA, which may reflect down-regulation of the sympathetic nervous system in response to carotid sinus stimulation during carotid angioplasty.