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Biomedical subjects

K Craig Kent

Publications and source records attributed to K Craig Kent.

85 records · Page 5Linked to original sources

Bolus arterial-venous transit in the lower extremity and venous contamination in bolus chase three-dimensional magnetic resonance angiography.

RATIONALE AND OBJECTIVES: To investigate the phenomena and causes for undesired venous signal in the distal station of bolus chase 3D MRA. METHODS: Consecutive patients (in 8 months) undergoing peripheral MRA consisting of 2D projection MRA of the tibial trifurcation and 3D bolus chase MRA were retrospectively evaluated. Venous contamination in mid-calf in bolus chase 3D MRA was correlated to the arterial phase duration, the time between the contrast bolus arrival and venous return measured on time resolved 2D images. Statistical analyses were performed to identify the clinical parameters indicative of venous contamination. RESULTS: The arterial phase durations at the mid-calf were 49 +/- 8 seconds on 101 legs without venous signal in the bolus chase 3D MRA, 35 +/- 9 seconds on 13 legs with moderate venous signal, and 20 +/- 4 seconds on 40 legs with substantial venous signal; the differences were significant among different venous signal levels (P < 0.001 for all pairs). Legs with cellulitis had shorter arterial phase and more venous contamination than legs without cellulitis (P < 0.05). Patients with myocardial infarction had longer arterial phase and less venous contamination than patients without myocardial infarction (P < 0.01). CONCLUSION: Venous signal in the distal calf station of bolus chase 3D peripheral MRA is caused by fast arterial-venous transit. It is worse in legs with cellulitis and less in patients with a history of myocardial infarction.

Aged↗

Contrast material travel times in patients undergoing peripheral MR angiography.

PURPOSE: To retrospectively review time-resolved two-dimensional projection magnetic resonance (MR) angiographic data to characterize the passage of gadolinium-based contrast material down the leg arteries in patients undergoing peripheral MR angiography. MATERIALS AND METHODS: Data of 87 consecutive standardized peripheral MR angiographic examinations were retrospectively reviewed to determine contrast material arrival times to the common femoral artery (CFA), the popliteal and tibial arteries, and the corresponding veins. Travel times were correlated with clinical data obtained with retrospective chart review and predictive multiparameter models developed with stepwise linear regression. RESULTS: The mean travel time of contrast material to the CFA was 24 seconds +/- 6 (SD), with additional 5 seconds +/- 2 to reach the popliteal artery and 7 seconds +/- 4 to reach the ankle artery. The mean time window of arterial enhancement was 49 seconds +/- 10 in the pelvis, 45 seconds +/- 10 in the thigh, and 35 seconds +/- 14 in the calf. The travel time to CFA was correlated with aortic aneurysm (r = 0.41; P <.001), increasing age (r = 0.31; P =.003), male sex (r = 0.3; P =.005), myocardial infarction (r = 0.26; P =.016), and type 2 diabetes mellitus (r = -0.22; P =.041). Predicted travel time to CFA was 10.6 seconds, plus 0.143 seconds times patient age, plus 4.8 seconds if aneurysm was present, plus 3.8 seconds if male sex, plus 2.8 seconds if history of myocardial infarction. CONCLUSION: Contrast material injected intravenously traveled rapidly down the peripheral arteries at approximately 6 seconds per station, but a long arterial phase time window allowed bolus-chase peripheral MR angiography to function with slower table stepping. Patient-to-patient variations in contrast material kinetics may be anticipated on the basis of age, sex, and clinical parameters.

Adult↗

Recent advances in peripheral angioplasty and stenting.

Utilization of percutaneous interventions for arterial and venous occlusive lesions continue to increase. With the progression of the technology supporting these therapeutic measures, the results of these interventions may be expected to improve. In general, a comparison of techniques for revascularization demonstrates similar initial technical success rates for surgery and percutaneous transluminal angioplasty. Angioplasty is often associated with lower procedural morbidity and mortality rates. Conversely, surgery frequently provides greater long-term patency. Late failure of percutaneous therapies may often be treated successfully with reintervention, however. The continued accumulation of experience with PTA and stenting will ultimately define its role in the management of occlusive disease.

Angioplasty, Balloon↗

Rupture of excluded popliteal artery aneurysm: implications for type II endoleaks--a case report.

The fate of popliteal artery aneurysms after ligation and bypass is believed to be relatively innocuous. The patient presented in this report, however, experienced spontaneous rupture of a popliteal aneurysm 11 years after ligation and bypass. Magnetic resonance angiography was used to establish the diagnosis of rupture, which was subsequently confirmed at surgery. Intraoperative arteriography demonstrated persistent collateral arterial perfusion of the excluded popliteal aneurysm sac. The collateral arterial flow originated from the superior and inferior lateral genicular arteries. The persistent arterial perfusion resulted in growth of the aneurysm from 4.2 to 7.0 cm over the 11-year period. The ruptured aneurysm was successfully treated by direct arterial exposure and suture ligation of the collateral vessels performed from within the aneurysm sac. The development of popliteal aneurysm expansion and rupture as a result of collateral arterial perfusion suggests that persistent collateral perfusion of abdominal aortic aneurysms after endovascular repair (type II endoleak) may lead to aneurysm rupture. Therefore, close observation and intervention for aneurysm expansion to prevent rupture of the excluded aneurysm are warranted.

Aged↗

Postcarotid endarterectomy pseudoaneurysm treated with combined stent graft and coil embolization--a case report.

Pseudoaneurysm formation is a rare complication following carotid endarterectomy (CEA); however, its occurrence is associated with significant risk of morbidity. The patient in this report presented 2 years following CEA with headache and lateral neck mass. The diagnosis of a 3.5 x 3.0 cm carotid artery bifurcation pseudoaneurysm was made by using magnetic resonance angiography (MRA). Endovascular exclusion of the aneurysm was accomplished with coil embolization of the external carotid artery followed by deployment of a 7 x 50 mm wall stent graft into the common carotid artery-internal carotid artery (CCA-ICA). The patient's symptoms improved and at 6-months postexclusion, duplex ultrasound demonstrated a significant reduction in pseudoaneurysm size. This case highlights the feasibility and safety of using endovascular techniques in the treatment of post-CEA pseudoaneurysm.

Aged↗

Endoluminal recanalization in a patient with phlegmasia cerulea dolens using a multimodality approach-a case report.

Phlegmasia cerulea dolens is a limb-threatening form of deep venous thrombosis and should be treated aggressively. The authors report a patient who presented with iliocaval and femoral deep venous thrombosis and posed an additional therapeutic challenge based on a recent history of heparin-induced thrombocytopenia. Catheter-directed pharmacologic thrombolysis and balloon venoplasty were applied in treatment. The direct thrombin inhibitor argatroban was used in place of heparin for concurrent anticoagulation. This multimodality endovascular approach (chemical and mechanical interventions) was successful in relieving the venous occlusion and salvaging the limb, while maintaining appropriate treatment for heparin-induced thrombocytopenia.

Anticoagulants↗

Multimodal therapy for acute and chronic venous thrombotic and occlusive disease.

Critical deep venous thrombosis and occlusion constitutes a small percentage of patients with venous disease. However, these patients exhibit severe symptomatology including pain and extensive edema that may progress to limb- or life-threatening complications such as phlegmasia cerulea dolens and superior vena cava syndrome. This paper reviews the different multimodal percutaneous interventions currently available for the treatment of complex critical venous thrombotic and occlusive disease.

Acute Disease↗

Embolization of renal artery aneurysm and arteriovenous fistula-a case report.

A renal artery aneurysm with an associated arteriovenous fistula in a native kidney has been reported infrequently in the literature. Management depends on size, location, and the patient's physiological condition. We describe a case in which endovascular therapy was used to successfully exclude both aneurysm and fistula. This report describes a 13-centimeter renal artery aneurysm with arteriovenous fistula originating from an isolated branch of the renal artery. Coil-embolization resulted in thrombosis of the aneurysm and fistula while preserving parenchymal perfusion. Coil embolization is an alternative to surgery for coexistent renal artery aneurysm and arteriovenous fistula arising from a branch of adequate length for placement of embolic coils. Successful treatment is not limited by aneurysm size or presence of arteriovenous connection.

Aneurysm↗

Current management of extracranial carotid artery disease.

Stroke is the third most common cause of death in the United States. There are approximately 700,000 strokes/year; 80% are ischemic, and 20-30% of ischemic strokes are secondary to carotid disease. Carotid stenosis is traditionally treated by carotid endarterectomy (CEA). Multicenter, randomized, controlled trials have shown that surgery significantly reduces the risk of ipsilateral stroke in patients with severe symptomatic and asymptomatic carotid stenosis. Endovascular techniques for treating carotid stenosis have been developed over recent years. Carotid angioplasty and stenting (CAS) with cerebral protection has become an alternative to CEA for high-surgical-risk patients and the procedure of choice for stenoses inaccessible by surgery. In this review we summarize the existing data regarding the traditional state of management of extracranial carotid artery stenosis and compare these data to a critical analysis of the recent results of CAS.

Angioplasty↗

Experimental analysis of transvenous ultrasonography in localizing and grading renal artery stenosis.

This study evaluated the potential for transvenous ultrasonography to assess renal artery stenosis (RAS), the most common correctable cause of hypertension in the United States. We developed a porcine model for studying RAS using TVUS. An endovascular ultrasound probe was placed into the inferior vena cava and renal veins to image renal arteries in which stenoses had been surgically created in varied locations and to varied degrees. TVUS was then used to identify and assess these stenotic lesions. The accuracy of TVUS for determining the degree and location of the stenoses was then determined using contrast arteriography as the standard. When compared with arteriography, TVUS identified and properly located all six lesions and correctly quantified the degree of stenosis in five of the six lesions. TVUS is an effective means of assessing the presence, degree, and location of stenotic lesions of the renal arteries in this animal model. Study of this method in humans may be warranted.

Animals↗

Endoluminal recanalization in a patient with phlegmasia cerulea dolens using a multimodality approach.

Phlegmasia cerulea dolens, a rare complication of deep venous thrombosis, has traditionally been difficult to treat. The patient described in this report posed additional therapeutic challenges based on a history of heparin-induced thrombocytopenia. She presented with severe leg pain and swelling, and a venogram showed occlusion of both her inferior vena cava and right iliac vein. The use of a multimodality approach, both chemical and mechanical, was successful in removing the venous occlusion, thereby preventing further complications, such as circulatory shock, postphlebitic syndrome, and venous gangrene.

Catheterization↗

Models of abdominal aortic aneurysm: characterization and clinical applications.

Abdominal aortic aneurysms (AAAs) are responsible for considerable morbidity, mortality, and cost to society. The pathogenesis of AAA formation, however, remains poorly understood. Animal models have been used in a range of experiments designed to provide further objective scientific assessment of the pathogenesis as well as the treatment of AAA. The purpose of this manuscript is to review the current models of AAA and their potential clinical implications.

Animals↗