PREVALENCE AND MOLECULAR CHARACTERIZATION OF DIROFILARIA IMMITIS (FILARIOIDEA: ONCHOCERCIDAE) IN DOGS FROM ENDEMIC AREAS OF RIO DE JANEIRO STATE, BRAZIL.

Canine dirofilariasis is common in Brazil, but molecular diagnosis is rare even though molecular studies increase our knowledge about molecular epidemiology and circulating genotypes from helminths worldwide. This study aims to estimate the prevalence of infection with a modified Knott's test and to perform molecular characterization of Dirofilaria immitis (Leidy, 1856) Railliet and Henry, 1911, in dogs from endemic areas of Maricá and Niterói municipalities, Rio de Janeiro State, Brazil. Molecular characterization was performed in 33 blood samples from dogs positive for microfilariae and 4 adult worms obtained from 2 other dogs. DNA extraction followed by PCR for mitochondrial target 12S rDNA and cytochrome oxidase subunit 1 (COI) of D. immitis were performed, and the amplified products were sequenced. All sequences were identical for both gene targets and showed 100% identity with D. immitis sequences from different animal species from various countries. The study concluded that this genotype of D. immitis might be dispersed worldwide.

Limb ischemia during intra-aortic balloon pumping: indication for femorofemoral crossover graft.

Catheter insertion for intra-aortic balloon pumping (IABP) was successful in 91% of 332 candidates. Fifty-three patients (16.5%) had significant catheter-associated vascular complications, of which lower extremity ischemia with threatened limb loss was the most prevalent (70%). Thirty-six of these patients required an angioplastic repair or vascular grafting. Of the 36, 19 patients with ischemia who needed continued balloon support received femorofemoral (F-F) grafts to restore and maintain adequate limb perfusion. Wound infection occurred in six of the patients but there was no limb loss. F-F grafting is a simple procedure that requires little time and allows one to maintain IABP for prolonged periods without concern for critical obstruction to limb perfusion.

Iatrogenic entrapment of femoropopliteal saphenous vein bypass grafts by the gastrocnemius muscle.

Two patients are described in whom saphenous vein grafts placed distal to the knee joint were "entrapped" by the medial gastrocnemius tendon. In one, the superficial position of the graft was detected by postoperative angiography. In the other, a true aneurysm of the vein graft developed over a 3 year period. The similarity between the iatrogenic and congenital forms of the popliteal entrapment syndrome is noted.

Crossover femorofemoral grafts followed up five years or more. An analysis.

Crossover femorofemoral grafts continue to provide satisfactory long-term patency with low morbidity and mortality in the treatment of unilateral atherosclerotic iliac artery occlusion. In our series of patients, early failures were primarily a result of the inability to provide adequate runoff for the graft, and late failures were due to progressive atherosclerotic involvement of runoff vessels. Clear-cut progression of the atherosclerotic process in the donor iliac artery segment has not been observed in this series. In fact, there is evidence that suggests that this process may have been retarded when compared with other types of reconstructive procedures. There is a noticeably late mortality (33%) due to other disease processes and associated cardiovascular disorders. These facts continue to support the application of crossover femorofemoral grafts in the surgical treatment of unilateral atherosclerotic illiac artery occlusions.

Peripheral nerve division for relentless ischemic foot pain.

During a three-year interval, 12 multisensory peripheral nerve divisions in ten patients were performed for intractable ischemic foot pain. The two major indications, after concluding that revascularization was impossible, were (1) the presence of localized, dry, and contained acral gangrene in patients who were not candidates for a lesser amputation and (2) patient or family refusal of a limb amputation.

A 12-year experience with femorofemoral crossover grafts.

One hundred thirty-three patients with unilateral iliac artery obstruction were treated with crossover femorofemoral grafts and followed up for one to 12 years. Cumulative patency was 73.3% at five years and 63.6% at ten years. There were 17 early closures with ten unsuccessful revisions and 22 late failures between three and 122 months. Inability to establish adequate runoff was the primary cause of early failure, and the progression of distal disease was the major cause of late failures. In only five cases did progressive disease of the donor artery cause failure of the graft. Operative morbidity and mortality were low (6%), and the results compare favorably with alternative methods of treating unilateral iliac artery occlusions.

Infected aneurysms of the abdominal aorta.

Infected aneurysms of the abdominal aorta are relatively uncommon, but potentially lethal if improperly managed. Two case reports emphasize the importance of the preoperative aortogram for accurate diagnosis. We stress the principles of total excision of infected tissue and revascularization in uninfected tissue planes. A useful vascular reconstructive technique consisting of unilateral axillofemoral bypass and an ilioiliac anastomosis was used in both patients.

Vascular complications of intra-aortic balloon pumping.

Vascular injury or occlusion from intra-aortic balloon pumping (IABP) that results in actual or potential limb ischemia occurs more frequently than reported. In a series of 79 IABP patients, 36 lived long enough to have the balloon catheter removed; thirteen (36%) of them had vascular complications. The complications were in three patients with an injury at the insertion site, eight patients with arterial thromboses, and two with arterial occlusion by the large balloon catheter. Local artery revision, thrombectomy alone, or thrombectomy with femorofemoral cross-over grafting was required in 11 patients. Femorofemoral crossover graft was utilized when arterial occlusion would have ordinarily required premature balloon removal or when immediate arterial occlusion by the catheter was recognized at the time of balloon insertion. This was preferable to transferring, replacing, or discontinuing IABP, since the same factors that led to thrombosis in the first place would have eventually come into play again. Patients should be observed frequently and have Doppler limb pulse determinations every four hours to avoid ischemic catastrophies. Proper IABP weaning and the use of a Fogarty catheter at the time of balloon removal is mandatory to prevent complications. Femorofemoral crossover graft is indicated for ischemic limbs when IABP must be continued.

Combined off-pump myocardial revascularization and carotid endarterectomy: early experience.

BACKGROUND: Controversy remains regarding the optimal surgical management of patients with coexisting significant carotid and coronary artery disease. The debate has deepened by the evolution of new approaches for the treatment of both coronary and carotid disease. We report our early experience with combined off-pump coronary artery bypass (OPCAB) and carotid endarterectomy (CEA) for the treatment of patients with coexisting coronary and carotid disease. METHODS: Our computer database was examined to obtain patients and their demographics and clinical profiles. Operative reports were reviewed. Telephone interviews were conducted to assess follow-up status. RESULTS: Thirteen patients underwent combined OPCAB and CEA. Average age was 71 years. The CEA was performed with intraluminal shunting and patch reconstruction. On average, 3.6 bypass grafts were performed. There were no gross neurologic complications or myocardial infarctions. Excluding an outlier, mean length of hospital stay was 8.2 days. All patients were well on follow-up (2 weeks to 16 months). CONCLUSIONS: A combined OPCAB and CEA strategy appears safe and effective. Further follow-up and experience is warranted before conclusions regarding potential benefits of this approach for staged or conventional OPCAB/CEA procedures can be made.

Ultrasound-guided balloon angioplasty is a new technique for vascular surgeons.

A new catheter has been developed that can be accurately and precisely positioned using duplex ultrasonography alone. A piezoelectric transducer that functions as a passive, omnidirectional receiver is attached to the mid-balloon region of an angioplasty catheter. Integration to a standard duplex imaging system allows visualization of this receiver in all planes, with the location of the receiver represented by a flashing bright arrow superimposed on the ultrasound B-mode image. This catheter was tested successfully in 10 dogs with bilateral femoral arteriovenous fistulas. With the use of duplex guidance, eight arterial and three venous stenoses were dilated and two stents were placed. Catheter placements and therapeutic outcomes predicted by ultrasound correlated with arteriographic findings. Ultrasound guidance has several advantages. It eliminates the risks associated with radiographic imaging. It also reduces patient costs and discomfort. Furthermore, procedures can be monitored continuously in real time with the collection of anatomic and physiologic data.

Endothelial cell adaptation to chronic thrombosis.

BACKGROUND: The autogenous vein graft has proven to be the most durable conduit in lower extremity vascular bypass grafts. Failures due to thrombosis, intimal hyperplasia, and progression of atherosclerotic disease commonly plague the vascular surgeon. Part of the ability of vein grafts to provide a nonthrombogenic surface relies on the capability of the endothelial cell to produce prostacyclin, a potent vasodilator and inhibitor of platelet aggregation. Once a graft fails and thromboses, little is known as to the effects of the thrombus on the function and morphology of endothelial cells. Earlier studies by this laboratory demonstrated the ability of arterialized canine vein grafts to recover function after 5 days of exposure to thrombus. This investigation sought to explore the limits of endothelial cell viability and recovery to extended periods of thrombosis. METHODS: Using a canine model of arterialized vein grafts, prostacyclin production (measured as 6-keto-PGF1a) was assessed in an ex vivo perfusion system from grafts exposed to thrombus for 10 days (group I) and 20 days (group II). Both groups underwent thrombectomy and a recovery period of 30 days. The grafts were perfused with Hanks' balanced salt solution and samples were obtained at 5 and 30 minutes to determine prostacyclin levels. Arachidonic acid was then added to a new perfusate of Hanks' solution and samples were again obtained at 5 and 30 minutes. Results were expressed as PGF/graft area (cm2/min). Representative samples of each graft underwent scanning electron microscopy. RESULTS: Without arachidonic acid, prostacyclin production of group II (20 day) grafts was greater than group I (10 day) grafts at 5 minutes of perfusion (4.31 versus 2.42, P = 0.08) and at 30 minutes (1.86 versus 0.95, P = 0.02). In response to the addition of arachidonic acid both groups increased prostacyclin production (group I, P = 0.004; group II, P = 0.12). A comparison was made between prostacyclin production at baseline and after addition of arachidonic acid. Group I grafts demonstrated a greater percent increase in prostacyclin production compared to group II (385% versus 229%, P = 0.01). Scanning electron microscopy showed no differences in endothelial coverage between the study groups. CONCLUSIONS: These results demonstrate that although endothelial cells are able to recover a basal level of prostacyclin production, the response to substrate stimulation diminishes with increased exposure time to thrombus. This diminished response may be important in understanding the ability of vein grafts to survive after a period of thrombosis.

The effect of thrombus on the vascular endothelium of arterialized vein grafts.

BACKGROUND: It is known that vein grafts can be salvaged by clot removal, but patency rates are diminished. This study was designed to determine the effects of thrombus on vascular endothelium and the ability of the endothelium to recover normal function. METHODS: Thirty external jugular vein grafts were placed as bilateral femoral artery interposition grafts in 15 mongrel dogs and allowed to arterialize for a period of at least 12 weeks. Six control grafts were not exposed to thrombus (C-NT). Six other control grafts were exposed to thrombus for 7 days and removed, ie, allowed no in vivo recovery (C-T). The remaining 18 grafts in 9 canines were exposed to autologous thrombus for 5 days and then flow was restored. The right femoral graft was removed 7 days after thrombectomy and the left removed 30 days after thrombectomy. At the time of removal, the grafts were perfused with a balanced salt solution alone and then with arachidonic acid added to the same volume of the salt solution. Perfusates were collected at 5, 15, and 30 minutes. These perfusates were assayed for the presence of 6-keto-prosglandin F1 alpha (6-keto-PGF1(1 alpha)), a metabolite of prostacyclin (PGI2). Over the 30-day recovery period, the amounts of 6-keto-PGF1(1 alpha) produced with and without arachidonic acid added were compared to assess endothelial response. Electron micrographs of the endothelium of all vein grafts were compared to the assay findings. RESULTS: When arachidonic acid was added to the perfusion system, there was a several fold increase in the production of 6-keto-PGF1(1 alpha) over baseline in all grafts allowed recovery. Grafts (C-T) that were allowed no in vivo recovery had no response to arachidonic acid. Ratios of 6-keto-PGF1(1 alpha) production with arachidonic acid stimulation to 6-keto-PGF1(1 alpha) production without stimulation were calculated to compare endothelial function. The electron micrographs showed the vascular endothelium to be severely injured after contact with thrombus, but recovered by 7 days. CONCLUSIONS: This study suggests that the endothelium of canine vein grafts is injured by contact with thrombus for 5 days but can recover structure and function. This recovery is detectable at 7 days post-thrombectomy.

Clinically recognized limb ischemia in the neonate after umbilical artery catheterization.

During a 4 year period, 1,461 critically ill neonates were admitted to the newborn intensive care unit of the Newark Beth Israel Medical Center, and 507 (35 percent) had umbilical artery catheters inserted for physiologic monitoring. In five patients (1 percent) clinically significant limb ischemia developed as a result of catheter complications. Frank gangrene was observed in three patients; two died from the primary illness soon after the onset of gangrene and the third survived after leg amputation. The other two infants had advanced ischemia that responded favorably to catheter removal and heparinization. Irreversible limb ischemia in this setting is infrequent, and milder forms are usually unrecognized or undocumented. High placement of the catheter or the length of time it is in place were not related to complications. Limb ischemia occurred soon after catheter insertion rather than after its protracted use. Major complications may be reduced by placement of the catheter in the lower abdominal aorta or internal iliac artery, clinical awareness and observation and frequent noninvasive monitoring. Immediate catheter removal and intravenous anticoagulation are warranted if ischemia persists. From this study, we believe that the benefits derived from judicious umbilical artery catheterization outweigh any inherent risk.

Treatment of acute vascular occlusions with intra-arterial urokinase.

This study reviewed 57 patients with 71 vascular occlusions treated with urokinase from 1985 to 1988. Of these patients, 89% were candidates for urgent surgery. Total clot lysis was achieved in 73% of cases. The success rate rose with increasing experience (p less than 0.05), and recent occlusions had more favorable outcomes than older ones (p less than 0.05). The length and type of occluded conduit (graft or vessel), age, sex, other medical conditions, and concurrent use of heparin had no influence on success. Of 18 cases successfully lysed and not subjected to any adjunctive therapy directed at the cause of occlusion, 9 (50%) reoccluded within 1 to 88 days (mean: 25 days). Cases successfully treated with thrombolysis and surgery or dilation of the causative stenosis had poor 1-year patencies: 17%, 20%, and 55% for vein grafts, prosthetic grafts, and native arteries, respectively. With additional urokinase treatments, surgical operations, and percutaneous procedures, 1-year patencies were 22%, 45%, and 65%, respectively.

An argument for increased use of subtotal colectomy in the management of carcinoma of the colon.

Subtotal colectomy (STC) is a safe operation because operative mortality rates are as good as, if not better than, conventional segmental colon resections. It is no more difficult to perform than conventional segmental resections. Suture line complications, such as fecal fistulas and suture line recurrences, are not as common before as they are after colocolic anastomoses. In addition to being used in cases with known synchronous carcinomas, and carcinoma associated with polyps, STC should be considered in selected patients with obstructing or partially obstructing lesions of the sigmoid or left colon when complete evaluation of the proximal colon has not been possible. STC can be combined with a preliminary transverse colostomy for obstructing left colon lesions when appropriate evaluation demonstrates suitable indications for the resection of the colostomy as a one-stage procedure with ileocolic anastomosis. It also should be considered if there is significant distal sigmoidal diverticular disease associated with proximal carcinomas. Statistically, STC does not appear to be indicated as a prophylactic operation to avoid the development of metachronous colon cancer when the entire colon can be surveyed colonoscopically to assure that there is no associated neoplasm.

Popliteal aneurysms.

A review of 64 popliteal aneurysms in 43 patients treated over a 14-year period revealed that thrombotic occlusion with ischemia and threatened limb loss was the most frequent complication (68%). Ten major amputations (23%) were necessary, four of which were the primary operations soon after admission. No limb loss occurred after operation in 11 patients with asymptomatic aneurysms. Direct revascularization was successful in 29 limbs (83%). Popliteal aneurysms should be resected, preferably in the asymptomatic stage, unless medical contraindications exist. Once thrombosis occurs, limb loss becomes a threatening likelihood.

Forward-looking intravascular ultrasonography: in vitro imaging of normal and atherosclerotic human arteries.

Inadequate guidance of angioplasty devices limits the endoluminal treatment of high grade atherosclerotic stenoses and total occlusions. Conventional intraluminal ultrasound systems (IVUS) enable lateral cross-sectional imaging of tomographic sections of the vessel wall, but do not offer imaging in front of the catheter. This study describes our initial experience with a forward-looking intravascular ultrasound (FL-IVUS) system (Echoeye, EchoCath, Inc., Princeton, NJ). The acoustic beam from a 25.5 MHz piezoelectric transducer on a 7.5 Fr catheter is mechanically rotated in a forward-looking spiral fashion at 300 cycles/second. Sixty-four axially aligned, cross-sectional, real time images are obtained from a truncated, 60 degree conical volume located 5 to 10 mm from the catheter tip. Luminal dimensions (n = 51) of human cadaveric femoral arteries (cast in agar and submerged in saline) measured by the FL-IVUS were compared to histologic cross-sections of the vessel with a correlation of r = 0.92. FL-IVUS accurately imaged the narrowing lumen in front of total occlusions and the geometry at vessel branches, and identified the location of lesions and the shape and morphology of vessel wall thickness. The 7.5 Fr FL-IVUS over-estimated luminal dimensions in vessels larger than 5 mm. We conclude that FL-IVUS imaging shows promise as a new, accurate method for identifying and characterizing high grade atherosclerotic stenoses and total occlusions, and expands the current capabilities of conventional IVUS systems.

Does low-dose aspirin therapy complicate oral surgical procedures?

BACKGROUND: The fear of uncontrolled bleeding often prompts medical practitioners to stop aspirin intake for seven to 10 days before any surgical procedure. The authors initiated this study to evaluate the effect of aspirin on bleeding in patients undergoing oral surgery. METHODS: The study group consisted of 39 patients who were scheduled to undergo dental extractions. All patients were receiving 100 milligrams of aspirin daily on a regular basis. The authors randomly divided the patients into two groups: those who stopped the aspirin therapy before the procedure and those who continued the aspirin therapy. One hour before the procedures, all patients underwent a bleeding time test. In addition, the amount of bleeding during the procedure was measured. RESULTS: The mean (+/- standard deviation) bleeding time was 1.8 +/- 0.47 minutes for patients who stopped aspirin therapy one week before the procedure. For patients who continued aspirin therapy, the bleeding time was 3.1 +/- 0.65 minutes. The difference was statistically significant (P = .004). However, both groups were within the normal bleeding time range, and in both groups, a local hemostatic method was sufficient to control bleeding. No episodes of uncontrolled intraoperative or postoperative bleeding were noted. CONCLUSION: Low-dose aspirin therapy should not be stopped before oral surgery. Local hemostasis is sufficient to control bleeding. CLINICAL IMPLICATIONS: Patients receiving aspirin therapy to prevent blood clot formation may be subject to emboli formation if the treatment is stopped. The results of this study show that aspirin therapy should be continued throughout oral surgical procedures. Local measures are sufficient to control any bleeding during surgery.

Ultrasound Guided Balloon Angioplasty: What is its Role?

A modified angioplasty catheter has been developed which can be guided-into position with duplex ultrasound. This reduces the risks of ionizing radiation and contrast agents and uses a modality familiar to the vascular surgeon. This catheter was tested successfully in a canine model for safety, accuracy and therapeutic efficacy. Following FDA approval, clinical trials in humans were initiated. This paper describes the preliminary results with use of this device in humans.