Thermodynamic correlates of hot tip laser angioplasty.

Surface temperatures of normal human cadaver arteries and polytetrofluoroethylene grafts were measured in vitro using thermography to assess vascular wall heating from the metal-capped ("hot tip") laser probe. Laser pulse duration, vessel diameter, blood flow, and saline infusion were varied; power from an Argon laser was constant at 10 watts. The surface temperatures resulting in perforation were 76.2 +/- 2.2 degrees C for arteries and 90.4 +/- 2.1 degrees C for grafts. Blood flow provided an effective heat sink reducing artery and graft wall peak temperatures from 10 watt/5 sec pulses by 12.2 +/- 1.7 and 14.1 +/- 6.1 degrees C at 100 mL/min, and by 16.3 +/- 2.4 and 22.4 +/- 4.9 degrees C at 500 mL/min, respectively. In the occluded conduit, inflow of saline proximal to the probe tip reduced peak temperatures (degrees C) from 10 watt/5 sec pulses as follows: 14.0 +/- 3.2 (artery) and 23.2 +/- 8.5 (graft) at 50 mL/min, and 19.0 +/- 0.6 (artery) and 26.6 +/- 8.5 (graft) at 100 mL/min. Radial heating by the hot tip probe can cause thermal perforation. Blood flow or saline infusion modifies nontarget heating and may offer significant protection to the vasculature.

A canine model of controlled thrombotic vascular occlusion.

The authors developed a reproducible canine model of arterial thrombotic occlusion. Operative isolation and occlusion of the external iliac arteries (EIA) were combined with balloon de-endothelialization and thrombin injection to induce bilateral thrombosis in 13 dogs. After three to nine days, 26 of 26 vessels contained isolated, discrete thrombi. Arterial blood flow reconstituted at the superficial/deep femoral artery bifurcation in 100% of cases, which limited the distal extent of thrombosis. Arterial dimensions measured intraoperatively showed thrombus volumes to be (mean +/- SD) 1332.1 +/- 243.1 mm3 (right) and 1335.9 +/- 246.8 mm3 (left). A 2-mm hot tip probe powered by an Argon laser was used to recanalize the occlusion in four vessels. Thrombo-ablation volumes accomplished by a single pass of the laser probe averaged 172 +/- 19.7 mm3 per vessel yielding thrombo-ablation energies between 2.6 and 3.5 J/mm3. Quantification of thrombi and simultaneous monitoring of both occluded segments by aortography as well as the large size of the EIA are advantages of this model, which is recommended for studies of thrombotic vascular occlusive disease.

Vagal schwannoma.

A patient with a benign encapsulated intrathoracic vagal schwannoma is presented and the literature is reviewed. The right paratracheal tumor was identified incidentally on a chest film and excised using a right thoracotomy. Although rare, vagal schwannomas should be considered for any mediastinal mass along the vagus nerves especially when the paratracheal tumor produces minimal or no respiratory symptoms suggesting a slow-growing, encapsulated process.

Complications of acute diverticulitis of the colon: improved early diagnosis with computerized tomography.

We have evaluated the diagnostic role of computerized tomography in 42 patients suspected clinically of having a complication of acute diverticulitis (abscess, colovesical fistula, or both). Diverticular abscesses were confirmed at operation in 10 patients. All 10 patients were diagnosed preoperatively on computerized tomography by the triad of diverticula, a segmentally thickened colon, and extravisceral fluid collection with (6 patients) or without (4 patients) associated gas. Contrast enema study suggested the presence of a diverticular abscess in only two of eight patients studied. Colovesical fistulas were confirmed in 12 patients. Eleven of 12 were diagnosed preoperatively on computerized tomography by the triad of air in the bladder, thickened colon adjacent to an area of thickened bladder, and the presence of colonic diverticula. Contrast enema examinations demonstrated the fistula in only three of eight patients studied. The remaining 20 patients proved to have uncomplicated acute diverticulitis. Findings on computerized tomography included the presence of a segmentally thickened colon with diverticula but without the findings of an abscess or a colovesical fistula. Computerized tomography correctly visualized acute diverticular complications in 21 of 22 patients and it excluded an abscess or fistula in all 20 patients with uncomplicated acute diverticulitis who were suspected of having a diverticular complication. Computerized tomography is the most sensitive and specific test for diagnosing complications of acute diverticulitis. It should be an early consideration in patients with suspected diverticular abscesses or fistulas so that appropriate therapy is not delayed.

The changing spectrum of splenic abscess.

Thirteen cases of splenic abscess were reviewed retrospectively from pathologic and medical records from 1978 through 1986. Splenic abscess is uncommon, but the diagnosis has been made more frequently in recent years due to the increasing number of living immunosuppressed patients and to the use of more sophisticated radiologic diagnostic techniques. Five patients had a solitary abscess (SA) and eight had multiple abscesses (MA). Seventy-five percent of the patients with MA were immunosuppressed, most had no symptoms from the splenic abscess, and none died. Only one patient (with SA) died, a mortality of 10% overall. Previously the mortality has been 40 to 70%. The decreased mortality may in part be attributable to the more rapid diagnosis (3.8 days for SA, 1.8 days for MA) of the splenic abscess, prompting early treatment. Improved radiologic studies reduce the time to diagnosis and thereby improve the prognosis. Computed tomography (CT) was diagnostic for splenic abscess in 4 of 7 patients and suggestive of abscess in the other 3. Computed tomography was the diagnostic modality of choice in suspected splenic abscess, as it provided more information than the other radiologic studies used.

Nontraumatic focal lesions of the spleen: assessment of imaging and clinical evaluation.

Fifty-nine cases of nontraumatic splenic disease were reviewed to evaluate the roles of clinical findings, computed tomography, ultrasound, and radionuclide scanning in diagnosis and management. Patient groups included lymphoma (30 patients), infarct (11 patients), abscess (9 patients), cyst (5 patients), hemangioma (3 patients), and hamartoma (1 patient). In no case were clinical findings alone sufficient to diagnose a splenic lesion. Clinical and laboratory manifestations were nonspecific in all groups. Moreover, no radiologic study reliably diagnosed splenic lymphoma or leukemia. All other focal splenic lesions were consistently diagnosed noninvasively. Cross-sectional imaging was more useful than radioisotope scanning, and often provided adjunctive diagnosis of extrasplenic pathology. The superior detail, spatial resolution, and sensitivity of computed tomography made it the single most valuable diagnostic modality.

Analysis of solid phase debris from laser angioplasty: potential risks of atheroembolism.

Laser energy can vaporize biologic tissues, and this unique method of ablation has been considered for the disobstruction of the occlusive lesion in atherosclerotic disease. To assess the potential embolic sequelae from laser angioplasty, solid phase debris (SPD) was analyzed. Specimens of human cadaver aorta were subjected to standardized argon laser injury, and SPD was quantified by weight in four types of ablated tissue: normal aortic intima, fatty streaks, fibrous plaque, and calcified plaque (CP). The debris by weight of tissue ablated was significantly higher for CP (p less than 0.05), measuring 7.9%, whereas normal aortic intima, fatty streaks, and fibrous plaque yielded 3.2%, 2.7%, and 3.7%, respectively. Likewise, the amount of debris liberated per unit volume of albated tissue was greatest for CP averaging 156 mg/cc. Light and scanning electron microscopy of SPD revealed carbonized tissue particles up to 350 mumol from all classes and cholesterol crystals up to 250 mumol from CP. SPD from CP was infused into renal arteries of rats at two dosages, 4 and 16 mg, to observe effects on end-organ tissue. At 10 days, all kidneys demonstrated focal ischemic atrophy and recovering acute tubular necrosis in a dose-dependent fashion (p less than 0.05). Control rats showed no disease. Kidneys embolized with SPD also displayed foreign body granulomas (9 of 12), periarterial inflammation (11 of 12), and cortical wedge infarcts (10 of 12). Argon laser energy that ablates tissue predominantly by thermal mechanisms liquified or vaporized 96% to 97% of noncalcified atheromatous material. Laser ablation of CP, however, liberated significantly more SPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Superior gluteal artery steal syndrome.

A sacral ulcer is described where ischaemia due to a vascular "steal" syndrome in the gluteal angiotome was the cause of persistent failure of flap reconstruction. Thrombotic obliteration of the abdominal aorta had resulted in the development of collaterals which, paradoxically, deprived the flaps based on standard angiotomes of their major source of blood supply, as they became the major source of perfusion for the legs. Healing of the ulcer was successfully achieved only after aorto-iliac reconstruction. Two other cases of ischaemic sacral ulceration, associated with aortic occlusion, are described.

The role of three-dimensional computed tomography in the evaluation of acute craniofacial trauma.

Three-dimensional computed tomographic (3-D CT) reformations together with their corresponding conventional axial two-dimensional (2-D) CT images of 20 patients with facial fractures were compared with 2-D CT alone to define their usefulness in the determination of facial skeletal fracture patterns. Nine surgeons with three different levels of experience and training evaluated the presence and spatial arrangement of fractures in all 2-D CT and 3-D CT scans. Comparisons were made between their evaluations of 2-D CT alone and 2-D CT plus 3-D CT scans. Statistical analysis with Friedman's test were performed. The addition of 3-D CT did not alter the interpretation of 2-D CT in 75% of evaluations. The number and accuracy of the changes made with the aid of 3-D CT reflected the experience of the observers. Overall, there was no improvement in the accuracy of interpretations with the addition of 3-D CT.

Experimental treatment of thrombotic vascular occlusion.

The role of laser energy in the treatment of thrombotic vascular occlusion was evaluated in two sets of experiments. First, 10 polytetrafluoroethylene grafts were used to replace segments of the superficial femoral arteries in dogs and were thrombosed by distal ligation. Occlusion was maintained for one hour, or for 7, 14, 21, and 28 days in each of two grafts. Patency was restored in all 10 grafts without perforation or anastomotic disruption using a 2 mm hot tip probe powered by an Argon laser. However, increased organization of thrombus related to the duration of occlusion lead to decreased laser channel diameters, and 75% of the 28 day thrombus remained in the graft after recanalization. The second experiments tested the added benefit of thrombolytic infusion following laser recanalization. Bilateral external iliac artery thrombosis was induced in dogs by operative vessel isolation, de-endothelialization, and thrombin injection. At 7 days the efficacy of laser-assisted thrombolysis (LAT) versus enzymatic thrombolysis (ET) alone was compared. Eight vessels underwent ET by urokinase (4000 I.U./min.); 14 vessels were laser recanalized prior to thrombolytic infusion. LAT was performed from a carotid artery approach in 8 vessels (antegrade) and from a femoral artery in 6 vessels (retrograde). In contrast to studies using the hot tip alone, both ET and LAT accomplished complete thrombus removal. However, LAT lead to significant iliac arterial flow in 9 +/- 8 min. (antegrade) and 25 +/- 8 min. (retrograde) while ET required 109 +/- 47 min (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic disease associated with pregnancy.

Our experience with the management of two patients with life-threatening aortic disease during pregnancy is presented with a review of the literature. One of our patients had intimal disruption caused by trauma; the other had probable Ehlers-Danlos type IV syndrome, causing an acute dissection of the descending thoracic aorta and eventually requiring replacement of the aorta from the left subclavian artery to common iliac arteries. The challenge of treating both the pregnant woman and the fetus was managed successfully by an emergent cesarean section followed by Dacron graft replacement of the descending thoracic aorta. The literature reviewed disclosed that aneurysm expansion producing symptoms and dissection is most common during the third trimester and during labor and delivery in patients with or without Marfan's syndrome. Half of the aortic dissections in women less than 40 years of age occur in association with pregnancy. The available evidence indicates that patients with known valvular or aortic disease should have surgical repairs during the first or second trimester and thereafter have delivery by cesarean section. However, patients with acute aortic problems near term appear to be better managed by cesarean section followed promptly by treatment of the aortic disease.