Search

Systemic thromboembolism is a severe complication in patients undergoing electrical cardioversion (ECV) for atrial fibrillation (AF). Vitamin K antagonists greatly reduce the risk of thromboembolic events, but the administration scheme before ECV is troublesome as difficulties in reaching and maintaining the target therapeutic range for 3 weeks often delay the restoration and likelihood of maintaining sinus rhythm. Low molecular weight heparins (LMWHs) do not need dose adjustment, and may be preferable in this clinical setting. In this multicentre study, the LMWH parnaparin was used at a dose of 85 anti-factor Xa U/kg b.i.d. 2 weeks before and 3 weeks after ECV of AF. In an intention to treat analysis of 102 patients, there was no systemic thromboembolism or major bleeding (0%, 95% CI 0-3.6). Two clinically relevant non-major bleeds (2.5%, 95% CI 0.7-8.8) and three minor bleeds (3.8%, 95% CI 1.3-10.6) were recorded. No heparin-induced thrombocytopenia or other major adverse events were recorded. Parnaparin appears effective and safe for thromboprophylaxis of elective ECV in patients with AF.

Purpose: To evaluate videoscopic ultrasonography (VUS) as a guiding method for endovascular aortic stent placement., Methods: Eight pigs were prepared for a videoscopic approach to the abdominal aorta. Through the trocarts, a VUS probe was placed in contact with the infrarenal aorta and iliacs. In the first 4 animals, a standard surgical approach was used to gain access to the right femoral artery. In the last 4 animals, 1 extra 5-mm port was positioned to provide a right arterial iliac access; thus, the approach for the endovascular procedure and for perioperative VUS guidance were therefore, totally videoscopic. In both approaches, under continuous perioperative VUS guidance, a guidewire was positioned upstream to the renal arteries. Then, a balloon expandable stent was deployed just below the lowest renal artery. All the VUS dynamic images were recorded on video. The pigs were euthanized and the infrarenal aorta was harvested to check that the stent had been positioned correctly., Results: The endovascular procedures were completed successfully in all animals. There were no bleeding complications in the 2 groups of animals and no mismatch between the aortic diameters and the selected balloon/stent sizes. All the stents were deployed 1 to 3 mm below the lowest renal artery., Conclusions: VUS proved an excellent imaging technique for guiding abdominal endovascular procedures on pigs. After further evaluation, this method could be applied in human beings during videoscopic vascular interventions or as a specific imaging method in the future with the development of endovascular procedures by videoscopic approaches.

Post-myocardial infarction left ventricular pseudoaneurysm resulting from free wall rupture is a rare finding and its recognition during life is uncommon. The diagnosis is difficult since symptoms, clinical evaluation and electrocardiographic and X-ray findings are usually non-specific. We herein present a case of a pseudoaneurysm manifesting after a silent myocardial infarction and diagnosed at echocardiography in a patient who, at the time of hospitalization, had a history and clinical and laboratory findings suggestive of pulmonary embolism. The patient was successfully operated. The present report underlines the diagnostic and prognostic value of two-dimensional transthoracic echocardiography. The clinical and laboratory findings are also discussed in the light of the recent literature.

Purpose: To develop laparoscopic techniques for aortic stent-graft placement as an alternative to the femoral approach., Methods: Endovascular stent-grafts were placed in 8 pigs via a totally laparoscopic retroperitoneal approach. After needle puncture, a guidewire was inserted into the abdominal aorta, followed by an 18-F sheath through which a Talent stent-graft was deployed in the descending thoracic aorta without aortic clamping. All the endovascular tools were inserted into the retroperitoneal area via the ports. After the sheath was withdrawn, hemostasis was achieved by suturing the aortic puncture under aortic cross-clamping. After sacrificing the animals, the thoracic aorta was removed to verify the position and deployment of the stent-grafts., Results: Seven (87.5%) of 8 procedures were successfully completed; the first animal died from hemorrhage due to inadvertent injury to the posterior infrarenal aortic wall. The accurate deployment and position of the stent-grafts were verified visually after sacrifice. Mean (+/- SD) procedural, implantation, and aortic cross-clamping times were 205 +/- 56, 22 +/- 9, and 30 +/- 19 minutes, respectively. Mean blood loss was 120 +/- 56 mL., Conclusions: Thoracic aortic stent-grafting using a laparoscopic approach to the infrarenal aorta is feasible. More studies will be required to define the place of combined endovascular and laparoscopic procedures as an alternative to the femoral surgical approach for stent-graft placement.

Purpose: To examine the structure and healing characteristics of chronically implanted Stentor endografts that were explanted due to migration, endoleak, thrombosis, or aneurysm expansion., Methods: The devices were harvested following reoperation (n = 5) or autopsy (n = 1) with implantation times ranging from 13 to 53 months. Structural modifications to the metal components were examined using radiography, endoscopy, and magnetic resonance imaging (MRI). Specimens taken from components of the modular stent-grafts were examined histologically and with scanning electron microscopy (SEM) to assess healing behavior. Physical and chemical stability of the nitinol wires and woven polyester graft material was evaluated using SEM and electron spectroscopy for chemical analysis., Results: Although the endografts were retrieved for a variety of reasons, they exhibited similar healing and structural modifications. The woven polyester sleeve showed evidence of yarn shifting and distortion, yarn damage, and filament breakage leading to the formation of openings in the fabric. The luminal surface endografts showed incomplete healing characterized by a poorly organized, nonadherent thrombotic matrix of variable thickness. Radiographic and endoscopic observations indicated that structural failure of the grafts, particularly in the main aortic component, was related to severe compaction and dislocation of the metallic frame due to suture breaks. Corrosion marks were observed on some nitinol wires in all devices. Chemical analysis and ion bombardment of the nitinol wires revealed that the surface concentrations of titanium and nickel were not homogenous. The first layer was composed of carbon or organic elements, followed by a stratum of highly oxidized titanium with a low nickel concentration; the titanium-nickel alloy lay beneath these layers., Conclusions: Although the materials selected for construction of endovascular grafts appears judicious, the assembly of these biomaterials into various interrelated structures within the device requires further improvement.

Purpose: To report the emergent endovascular management of an external iliac artery (EIA) rupture after standard guidewire recanalization and balloon angioplasty., Method and Results: A 54-year-old diabetic male presented with an occlusion of the EIA associated with severe stenotic lesions of the femoral bifurcation. Guidewire recanalization of the lumen was followed by balloon angioplasty, but evidence of EIA rupture was detected on the intraoperative arteriogram. Temporary homeostasis was achieved using the angioplasty balloon, and a Cragg EndoPro System 1 stent-graft was inserted transluminally to repair the injury. At 18 months poststenting, routine color Doppler confirmed continued patency of the vessel repair., Conclusions: While rupture of the EIA during angioplasty usually demands open surgical correction, an endovascular procedure can provide a fast, efficient, and less aggressive method of treating this serious complication.

The intraluminal elastase perfusion model has been proved to be potentially effective in producing abdominal aortic aneurysm in rodents, but it produced unpredictable results in larger animals. The purpose of this study was to explore the potential ability of such a model to produce experimental aneurysm consistently in the Yucatán miniature swine. Six Yucatán miniature swine received infusion with porcine elastase into an isolated segment of the infrarenal aorta. The excised arterial segments were examined macroscopically to assess the luminal surface characteristics and histologically to describe the different pathologic injuries induced by the elastase treatment on the intima, media, and adventitia of the arterial wall. Histologic examination revealed that the elastic network of the media was destroyed. In the first week after perfusion, altered smooth muscle cells were located in the intima and innermost layer of the media in juxtaposition with the occlusive thrombus. Infiltration of inflammatory cells was observed in these regions of elastic network and smooth muscle cell alterations. In the arterial segments of swine sustained for 3 weeks, a reduction of smooth muscle cells was noted in some areas. An important number of necrotic lesions was observed, and they were associated with the development of calcium deposits. Significant intimal hyperplasic reaction was identified at day 19 and again at day 21. However, no aneurysmal development was observed. This study constituted the first experiment with infusion of porcine elastase in the Yucatán miniature swine infrarenal aorta. The present experimental protocol induced important elastic network and smooth muscle cell alterations leading to severe necrotic lesions associated with calcium deposition, but it produced no aneurysmal dilatation. This model requires further testing to obtain a more complete degradation of the elastic network in both the media and adventitia and more significant collagenolysis without early thrombotic events.

Purpose: Recent advances in magnetic resonance imaging (MRI) technology may provide a safer and more sensitive monitoring modality than X-ray imaging for endovascular surgical procedures. The purpose of this study was to investigate the feasibility of using MRI to monitor the insertion of endoprostheses., Methods: The endoprostheses we studied were composed of a nitinol stent encased in a polyester sheath. These were characterized with four different MRI techniques: the fast spin-echo; spin-echo; gradient-recalled echo; and the spoiled gradient-recalled echo. The deployment of the endoprosthesis into an artery was simulated in an in vitro model and viewed using a fast spin-echo MRI technique., Results: Image artifacts produced by the nitinol framework in these endoprostheses were minimal when fast spin-echo or spin-echo imaging techniques were used, improving the visibility of the device. In in vitro tests, the catheters and endoprostheses were visualized by MRI with sufficient clarity to guide the placement of a device in the model artery., Conclusions: Insertion of this type of endoprosthesis under interventional MRI guidance is feasible. The convenience and improved safety provided by interventional MR systems and "real-time" imaging capabilities are expected to make this technology an attractive alternative to X-ray imaging techniques.

Objective: To test the hypothesis that chelation therapy with deferoxamine would prevent alterations in left ventricular systolic and diastolic function due to transfusional iron overload in patients with thalassemia major., Design: A consecutive series of patients receiving chronic transfusional and chelation therapy were studied by two-dimensional and Doppler echocardiography., Setting: Primary clinic., Patients: Eight thalassemic patients (four men and four women), mean age 22 years (range 14 to 28) and seven age and sex matched control subjects., Interventions: All patients had received transfusional therapy since birth, with mean annual load of red blood cells of 200 mL/kg. Iron chelation therapy with deferoxamine, using a subcutaneous infusion pump, was administered from age two years in the younger patients and from age 16 years in the two older cases. Doses were 25 mg/kg/day in children and 1.5 to 4 g per 12 h in adults to maintain ferritin blood levels at 1000 to 1500 ng/L., Main Results: No significant differences were found in the following Doppler diastolic indexes: isovolumic relaxation time, early flow velocity (E wave), late flow velocity (A wave), E:A ratio, rate of deceleration of flow velocity in early diastole (EF slope), flow velocity deceleration time and end-diastolic volume. Ejection fraction was similar in the two groups (59 +/- 7 versus 64 +/- 5%), but contractility, expressed as end-systolic pressure/end-systolic volume index, appeared slightly depressed (4.6 +/- 1 versus 6.7 +/- 0.8) in the thalassemic group., Conclusions: Deferoxamine prevents alteration of left ventricular diastolic function in chronic transfusional therapy for thalassemia major. Depression of contractility, in spite of a normal ejection fraction, may be an early sign of worsening systolic performance, unavoidable even with chelation therapy.

We report the case of a 79-year-old woman with severe aortic stenosis and alteration of left ventricular diastolic filling demonstrated by Doppler echocardiography, with inverted early/end diastolic flow profile. A sixteen month prospective follow-up study demonstrated progression of the illness, with further augmentation in transvalvular gradient and increased wall hypertrophy, but with apparent concomitant normalization of transmitral flow velocity profile. We conclude that a "normal" velocity pattern does not exclude an altered diastolic filling pattern, and must be interpreted with caution, in the light of all clinical and technical data.

The expanded polytetrafluoroethylene (ePTFE) vascular prostheses are widely used as small and medium diameter blood conduits when an autologous venous material is not available or is not suitable. The long-term performance of a prosthesis is dependent on several factors, including its healing characteristics and its stability in vivo. This study was undertaken to assess whether chemical degradation of ePTFE occurs when such arterial substitutes are implanted in humans. Seventy-nine ePTFE grafts excised for complications were analysed using the following techniques: measurement of the contact angle (theta), electron spectroscopy for chemical analysis (ESCA or XPS), Fourier transform infra-red spectroscopy (FTIR) and differential scanning calorimetry (DSC). The results were compared with those obtained from virgin ePTFE and virgin ePTFE washed prostheses. The measurement of the contact angle (theta) permits the comparison of the level of hydrophobicity of material after in vivo residency. The contact angles of explanted ePTFE grafts are greater than those of virgin ones but remain close to those of washed virgin prostheses. The ESCA method allowed investigation of the chemical changes which occur on the surface of ePTFE prostheses after implantation because of the low penetration of the X-ray (about 50 A). This study did not reveal any chemical degradation of the ePTFE with time of implantation for periods up to 6.5 yr. Changes in the surface composition were probably related to lipid and/or protein uptake. The FTIR spectroscopy provides information about the chemical composition of material. Compared with the virgin ePTFE prostheses, the FTIR spectra of explanted prostheses showed specific bands which are characteristic of lipid and/or protein absorptions. The bulk properties of ePTFE studied by DSC did not show any significant changes with time of implantation. It is concluded that ePTFE grafts remain stable in vivo for periods up to 6.5 yr.

To determine the etiology of anastomotic false aneurysms (AFAs), 26 textile graft specimens, removed because of AFA, were studied morphologically, histologically and by scanning electron microscopy. No cases of suture-related failures leading to AFA were found. Nine cases of frayed grafts were documented but were not the cause of AFA formation. In three cases, chemical degradation of the fibres, which may have been secondary to lipid infiltration, may have contributed to AFA formation. There were no cases of overt clinical infection, but the presence of bacteria was documented by scanning electron microscopy in 20 cases. The role of bacteria is not well defined, but they may be a factor in host arterial-wall degeneration as a cause for AFA formation.

Using a conical dilator as support during closure of arteriotomy improves the caliber of the vessel and makes its wall much more regular. This improvement has been confirmed by routine per-operative arteriography.

Twenty-one prosthetic explants were analysed after being surgically excised from 19 patients whose average age at implantation was 54.8 years. The arterial prosthesis was implanted 19 times for an advanced arteriopathy (stage III and stage IV) and twice for a stage II. The average time that the implants were in place was 14.8 months (with extremes of 19 days and 4 years). Surgical reintervention was caused by thrombosis (18 cases), infection (twice) and one case of degeneration of the prosthesis. The explanted prostheses displayed an irregular capsule, an uneven filling of the wall and a fibrous proliferation adhering to the internal surface. The role of the latter appeared essential to the prevention of the invasion of the prosthesis wall by fibrous tissues. The destruction of the structure of the microporous teflon is also prevented. Furthermore, this prosthesis seemed adversely affected when creased by flexion: the reduction in the caliber of the internal lumen caused thrombosis and a detachment of the external capsule. When such a material is implanted, everything must be done to prevent twisting or damaging the prostheses.

Through collaboration of surgeons, pathologists and bioengineers at five centers in Canada and France, this study analyzed the late pathology and structural changes in 73 expanded PTFE arterial prostheses harvested from patients at autopsies and reoperations. The degree of tissue encapsulation increased with the duration of implantation but was reduced by the presence of infection. In several cases, the fibrous tissue penetrated the wall of the prosthesis and partitioned off the thin outer layer, thus disrupting the delicate microporous structure of the wall. The presence of aneurysms was observed in models that had no external reinforcing layer and among grafts that apparently suffered from surgical trauma. Wrinkling of grafts was noted at areas of flexion and was often associated with thickening of the external capsule and reduced luminal diameters. Endothelialization was found within only a few millimeters of the anastomoses. The luminal surfaces were generally not well healed. The PTFE structure was usually readily visible under a thin covering of loosely adhering thrombotic deposits. Bacteria were observed in 46% of the cases, even though only 29% were considered clinically infected. The incidence of lipid or cholesterol deposits was high. Avoiding iatrogenic trauma to the external wall of the prosthesis during implantation is important. Those features where design improvements are required to provide longer term structural integrity and dimensional stability in future models of expanded PTFE prostheses should be identified.

The impact of routine intraoperative carotid angiography was evaluated by comparing 206 procedures without such angiograms with our last consecutive 100 endarterectomies with completion angiography. No significant age or sex differences were observed between the two groups. Exploratory surgery was repeated in five cases for a stenosis greater than 40% or for an intimal flap. This protocol reduced operative mortality (2.9% to 1%), the permanent stroke rate (1.9% to 1%), and the temporary stroke rate (6.3% to 1%). Furthermore, a second angiogram was performed in these 100 cases (at a mean interval of 19.2 months later) and the incidence and evolution of both residual and recurrent carotid lesions were analyzed. Five internal carotid artery lesions that had been immediately repaired because of intraoperative angiographic defects remained normal. Of 58 normal internal carotid arteries at the completion of surgery, two became stenotic during the next year. In addition, three spastic internal carotid arteries became normal. Of 20 internal carotid arteries with modest irregularities, 16 became normal and four were stenosed. Of three internal carotid arteries with intimal flaps, two became normal and one was stenosed. Among 13 internal carotid arteries with modest stenosis (40%), eight became normal, two became severely stenotic, and three became thrombosed. Among 21 instances of a proximal common carotid artery "shelf," 17 resolved and four progressed to less than 50% stenosis. Of 67 normal external carotid arteries, late stenosis was seen in one case. Of 33 external carotid arteries with residual stenosis, 17 became normal, 14 remained unchanged, and two were thrombosed.(ABSTRACT TRUNCATED AT 250 WORDS)

Restenosis of carotid arteries after endarterectomy is a rare complication; in our series 1.2% (19 patients - 20 recurrences out of 1658 operations - Dec. 1985). It usually occurs early, i.e. in the first months (12 cases) with features of myointimal hyperplasia. Peroperative angiography should be routinely performed to rule out technical errors that might be mistaken for restenosis. At the time of reoperation, 12 patients were symptomatic. The operation consisted of 6 second endarterectomies, 13 saphenous vein grafts and 1 PTFE graft. The postoperative period was uneventful in 14 cases, but in the remaining patients there were 2 transient ischemic attacks, 2 monoplegias and 1 dysphasia (with immediate thrombosis of the bypass in 3 cases). Five patients were lost at follow-up. In the remaining 14 patients, the follow-up period varied between 3 and 84 months (mean: 20 months). Presently 11 carotid arteries are patent. In one case involving a venous patch, the artery is dilated. All 12 of these patients are asymptomatic. One thrombosed bypass is also asymptomatic. The two monoplegias occurred in patients whose bypasses occluded immediately. The recurrence rate varied according to the imaging technique. i.e. pulsed Doppler, B-mode scanning or angiography, used to detect restenosis. Restenosis usually remains asymptomatic even in patients with hemodynamically significant lesions. Restenosis due to myointimal hyperplasia does not carry the risk of embolism and atheromatous stenosis does not have the same prognosis. In our experience immediate and long term results of red are not as good the first endarterectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Two years before admission a 72-year-old woman received an aortobifemoral bypass graft. When the graft became infected it was replaced by an axillofemoral bypass graft. This also became infected. In another attempt at revascularization, a bypass was installed between the lower part of the thoracic aorta and the two distal parts of the superficial femoral arteries, passing through the obturator foramen. Access to the lower part of the thoracic aorta was made through an abdominal incision, lowering the risk factors associated with such an intervention. At 18-month follow-up, the results were satisfactory; the graft was patent and not infected.

Prior to clinical use, this new myocardial stimulating electrode was studied in animals in order to test its electrical and mechanical reliability. The Telectronics 030.168 electrode consists of a conductor constructed of 3 stainless steel wires. Its present surface area is 25 mm and its length is 10 mm. The device is easily inserted into the myocardium with a suture and needle and is held in place with a surgical clip. We report observations on 42 patients made over an average follow-up period of 14.6 months. There were no surgical complications and there was no operative mortality. Calculated as an average of recorded electrical measurements, the stimulating threshold was 1.03 volts and 2.40 mA at 500 ms. None of the patients have required further surgery and no malfunctions have been discovered.