Roberto D. Cervera

Contemporary Relevancy of Carotid–Subclavian Bypass Defined by an Experience Spanning Five Decades

BACKGROUND The contemporary impact of and indications for carotid-subclavian bypass (CSB) are essential considerations in decision making for brachiocephalic reconstruction. METHODS We analyzed operative outcomes, long-term graft patency, and the extended epidemiological impact of the primary disease process in 287 consecutive patients (mean age, 60.6 years; 43.2% male) who received CSB for symptomatic brachiocephalic disease. RESULTS Technical success was achieved in each patient. Operative mortality was 1.0% (3/287) and total (ipsilateral [1.4%, 4/287] plus contralateral [0.7%, 2/287]) stroke rate was 2.1% (6/287). Primary patency rates at 5, 10, and 15 years were 94.2 ± 1.9%, 88.6 ± 3.2%, and 86.5 ± 3.8%, respectively. Kaplan-Meier freedom from specific events at 15 years was as follows: restenosis, 86.5 ± 3.8%; death, 67.5 ± 5.2%; coronary revascularization, 59.6 ± 6.3%; myocardial infarction, 82.8 ± 3.9%; stroke, 85.6 ± 4.9%; other vascular procedure, 60.0 ± 5.5%; adverse cardiac outcome (death, myocardial infarction, or coronary revascularization), 44.5 ± 5.5%; and adverse vascular outcome (restenosis, stroke, or other vascular procedure), 48.7 ± 5.3%. CONCLUSIONS CSB produces excellent long-term patency and extended symptom relief, with acceptably low operative morbidity and mortality. Despite the durability and success of CSB, the primary disease process has an adverse impact on long-term prognosis and significantly influences decision making with regard to management. The proven durability may offer extended symptom relief to the relatively younger patient, a survival advantage associated with preservation of internal mammary artery perfusion in patients at risk for myocardial revascularization, optimal durability in patients requiring a concomitant open procedure, and preservation of limb function in patients who require aortic endovascular graft placement.

Preclinical assessment of a trileaflet mechanical valve in the mitral position in a calf model.

BACKGROUND The bileaflet valve is currently the mechanical replacement valve of choice. Though durable, it does not closely mimic native valve hemodynamics and remains potentially thrombogenic. METHODS Prototype trileaflet valves (T1 and T2) were implanted in the mitral position in calves. Group I calves received either a T1 valve (n = 12) or a control bileaflet valve (n = 5); Group II, either a T2 valve (n = 7) or a control bileaflet valve (n = 5). Valve function, perivalvular leakage, and transvalvular pressure gradients were evaluated. Also, long-term prototype leaflet wear was evaluated in vivo in one Group I calf (502 days) and two Group II calves (385 and 366 days). Calves were euthanized and necropsied at study termination, and major organs weighed and examined. RESULTS Valve function was excellent and hematologic parameters remained normal in all calves that survived to study termination. Mean peak transvalvular pressure gradients were 10 +/- 7 mm Hg for T1 valves, 6 +/- 3 mm Hg for T2 valves, and 12 +/- 4 mm Hg for bileaflet control valves. Clinically insignificant valvular regurgitation was observed in both prototypes. Explanted valves showed no thrombus-impaired leaflet motion, except in two T1-fitted calves and one T2-fitted calf. Major organs showed no evidence of clinically significant thromboembolic events. There were no other significant differences between the results of experimental and control groups. CONCLUSIONS Prototype trileaflet valves performed safely and effectively in the mitral position in calves, even without long-term anticoagulation. This warrants their evaluation as an equivalent alternative to bileaflet valves.

Thrombogenicity of mechanical aortic valves in an animal model: site specific testing is crucial.

We evaluated a new trileaflet prosthesis and a control bileaflet prosthesis in the mitral and aortic positions in 27 calves. The prototype trileaflet valve (TV1) functioned satisfactorily in the mitral position (TV1m, n = 7) but later yielded thrombogenic complications in the aortic position (TV1a, n = 4). The valve was redesigned (TV2) and retested in the mitral (TV2m, n= 4) and aortic (TV2a, n= 5) positions, along with control valves (Cm, n= 4; Ca, n= 3). At necropsy, the valves were graded on a scale of 0 (no visible thrombi) to 4 (thrombi greater than 5 mm and/or obstructed leaflets). The TV1m, TV2m, and Cm animals, respectively, had implant durations of 215 ± 112, 140 ± 63, and 159 ± 89 days and thrombus grades of 0.71 ± 0.76, 0.33 ± 0.58, and 1.50 ± 0.58. The TV1a, TV2a, and Ca animals had implant durations of 18 ± 12, 159 ± 61, and 108 ± 62 days and thrombus grades of 2.75 ± 1.00, 0.50 ± 0.58, and 0.67 ± 0.58 (p < .005; TV2avs. TV1a). Three TV1a calves died early of valve related complications. A design irregularity, undetected in the mitral position but revealed in the aortic position, caused a high early mortality in the TV1a animals. Redesigning the prosthesis eliminated valve related mortality and significantly reduced the thrombus grade. Because satisfactory performance in the mitral position does not guarantee safety or efficacy in the aortic position, site specific preclinical testing is crucial for mechanical heart valves.

Preocclusive Carotid Artery Thrombosis: Pathogenesis and Management

In this report, the authors review the presentations, angiographic findings, and outcomes of eight cases involving patients who had atherosclerotic compromise of the proximal internal carotid artery and were developing distal thrombosis. They discuss the pathogenesis and implications of such lesions and review the management strategy used at this institution. Between 1994 and 1995, 606 consecutive patients underwent carotid endarterectomy (CEA) at this institution. Among this group, four consecutive patients (0.66%, 4/606) were identified by angiography to have preocclusive carotid artery thrombosis. An additional four patients with the same radiologic finding who had presented between 1980 and 1993 were also identified and included in this series. All eight patients were treated with anticoagulation and emergent CEA and thrombectomy. Complete resolution of presenting symptoms and freedom from perioperative stroke and death were achieved in seven patients (88%, 7/8). In one patient (12%, 1/8) the perioperative course was complicated by development of a carotid artery-cavernous sinus fistula and stroke. The catastrophic potential of preocclusive carotid artery thrombosis mandates immediate intervention. Anticoagulation, CEA, and thrombectomy can result in freedom from the adverse outcomes of stroke and death. However, special care must accompany thrombectomy in order to avoid complications and their associated morbidity.