Early spontaneous recovery of left ventricular function in patients with myocarditis.

The natural history of myocarditis is varied. We describe 6 out of a cohort of 15 consecutive patients with histopathologic evidence of myocarditis who showed a remarkable early symptomatic and spontaneous recovery of left ventricular systolic function. The left ventricular ejection fraction increased to > or = 50% at discharge, and this improvement was maintained at late follow-up. The other 9 patients, despite clinical improvement, were not thought to have spontaneous recovery. Neither clinical severity of the illness (NYHA functional class) nor left ventricular ejection fraction at presentation demonstrated any difference in the two groups. By contrast, a smaller left ventricular internal diameter at end-diastole and a smaller left atrial dimension as determined by transthoracic echocardiography were predictive of spontaneous recovery. Firstly, we confirm that the natural history of myocarditis is indeed varied with the possibility of early spontaneous recovery; secondly we suggest that left ventricular internal diameter at end-diastole and left atrial dimension may have prognostic implications in this disease.

High intensity focused ultrasound effect on cardiac tissues: potential for clinical application.

High intensity focused ultrasound (HIFU) is an evolving technology with potential therapeutic applications. Utilizing frequencies of 500 kHz to 10 MHz, HIFU causes localized hyperthermia at predictable depths without injuring intervening tissue. Applications in neurosurgery, urology, oncology and, more recently, cardiology for selective cardiac conduction tissue ablation have been promising. A 'noninvasive' technique for causing localized tissue damage to relieve hemodynamic and life-threatening obstruction in patients with congenital cardiac anomalies could replace more invasive procedures. We, therefore, investigated the ability of HIFU to create lesions in mammalian cardiac tissues ex vivo. Porcine valve leaflet, canine pericardium, human newborn atrial septum, and right atrial appendage were studied. Specimens were mounted and immersed in a water bath at room temperature. Using a 1-MHz phased array transducer, ultrasound energy was applied with an acoustic intensity of 1630 W/cm(2) or 2547 W/cm(2) until a visible defect was created (duration 3 to 25 sec). Macroscopic and microscopic examination demonstrated precise defects ranging from 3 to 4 mm in diameter. No damage was identified to the surrounding tissues. Our study concluded that HIFU can create precise defects in different cardiac tissue without damage to the surrounding tissue. Further investigation is needed to assess potential clinical uses of this technology.

Isolation and identification of the major urinary metabolite of 4-(4-fluorophenoxy)benzaldehyde semicarbazone after oral dosing to rats.

4-(4-Fluorophenoxy)benzaldehyde semicarbazone (1) is a novel anticonvulsant affording excellent protection in the rat oral maximal electroshock (MES) screen as well as having an apparent protection index of over 300. The metabolism of this compound was studied by examining the urine or rats dosed orally with 50 mg/kg of 1 which revealed that most of the drug was converted into one metabolite 2. The structure of 2 was shown by mass spectrometry to be 1-[4-(4-fluoro-phenoxy)benzoyl]semicarbazide which was confirmed by an independent synthesis. Compound 2 was bereft of activity in the rat oral MES screen when nine times the ED50 dose of 1 was administered. This datum provided strong evidence that the anticonvulsant activity of 1 and related compounds is due to the intact molecules and is not produced by breakdown products in vivo.

Effects of sulfanilamide and methotrexate on 13C fluxes through the glycine decarboxylase/serine hydroxymethyltransferase enzyme system in arabidopsis.

In C3 plants large amounts of photorespiratory glycine (Gly) are converted to serine by the tetrahydrofolate (THF)-dependent activities of the Gly decarboxylase complex (GDC) and serine hydroxymethyltransferase (SHMT). Using 13C nuclear magnetic resonance, we monitored the flux of carbon through the GDC/SHMT enzyme system in Arabidopsis thaliana (L.) Heynh. Columbia exposed to inhibitors of THF-synthesizing enzymes. Plants exposed for 96 h to sulfanilamide, a dihydropteroate synthase inhibitor, showed little reduction in flux through GDC/SHMT. Two other sulfonamide analogs were tested with similar results, although all three analogs competitively inhibited the partially purified enzyme. However, methotrexate or aminopterin, which are confirmed inhibitors of Arabidopsis dihydrofolate reductase, decreased the flux through the GDC/SHMT system by 60% after 48 h and by 100% in 96 h. The uptake of [alpha-13C]Gly was not inhibited by either drug class. The specificity of methotrexate action was shown by the ability of 5-formyl-THF to restore flux through the GDC/SHMT pathway in methotrexate-inhibited plants. The experiments with sulfonamides strongly suggest that the mitochondrial THF pool has a long half-life. The studies with methotrexate support the additional, critical role of dihydrofolate reductase in recycling THF oxidized in thymidylate synthesis.

The dissected aorta: part II. Differentiation of the true from the false lumen with intravascular US.

PURPOSE: To determine the intravascular ultrasound (US) features of aortic dissection that can be used to differentiate the true from the false lumen. MATERIALS AND METHODS: Intravascular US and aortography were performed in 34 patients with aortic dissection. Aortic necropsy specimens were available in five patients. True and false lumina in each patient were identified on the basis of surgical, necropsy, and radiologic findings. Intravascular US studies were reviewed with attention to several local imaging features, which were evaluated for sensitivity and specificity in the differentiation of true from false lumina. RESULTS: An acute angle between the dissection flap and the outer wall of the false lumen was found in 32 patients (sensitivity, 94%; specificity, 100%). The three-layered appearance of the intact wall of true lumen and single-layered appearance of the outer wall of false lumen were seen in 33 patients (sensitivity, 97%; specificity, 100%). Cobwebs were present in the false lumen in eight patients but were not seen in the true lumen (sensitivity, 24%; specificity, 100%). Aortic thrombus was seen in the false lumen in 10 patients but was not seen in the true lumen (sensitivity, 29%; specificity, 100%). CONCLUSION: Intravascular US findings can be used to differentiate the true from the false lumen in aortic dissection.

13C nuclear magnetic resonance detection of interactions of serine hydroxymethyltransferase with C1-tetrahydrofolate synthase and glycine decarboxylase complex activities in Arabidopsis.

In C3 plants, serine synthesis is associated with photorespiratory glycine metabolism involving the tetrahydrofolate (THF)-dependent activities of the glycine decarboxylase complex (GDC) and serine hydroxymethyl transferase (SHMT). Alternatively, THF-dependent serine synthesis can occur via the C1-THF synthase/SHMT pathway. We used 13C nuclear magnetic resonance to examine serine biosynthesis by these two pathways in Arabidopsis thaliana (L.) Heynh. Columbia wild type. We confirmed the tight coupling of the GDC/ SHMT system and observed directly in a higher plant the flux of formate through the C1-THF synthase/SHMT system. The accumulation of 13C-enriched serine over 24 h from the GDC/SHMT activities was 4-fold greater than that from C1-THF synthase/SHMT activities. Our experiments strongly suggest that the two pathways operate independently in Arabidopsis. Plants exposed to methotrexate and sulfanilamide, powerful inhibitors of THF biosynthesis, reduced serine synthesis by both pathways. The results suggest that continuous supply of THF is essential to maintain high rates of serine metabolism. Nuclear magnetic resonance is a powerful tool for the examination of THF-mediated metabolism in its natural cellular environment.

Induction of Lipid and Oleosin Biosynthesis by (+)-Abscisic Acid and Its Metabolites in Microspore-Derived Embryos of Brassica napus L.cv Reston (Biological Responses in the Presence of 8[prime]-Hydroxyabscisic Acid).

Microspore-derived (MD) embryos of Brassica napus L. cv Reston were used to test the effects of (+)-abscisic acid ([(+)-ABA]) and its metabolites, 8[prime]-hydroxyabscisic acid (8[prime]-OH ABA) and (-)-phaseic acid (PA), on the accumulation of very long-chain monounsaturated fatty acids (VLCMFAs) and induction of genes encoding a 19-kD oleosin protein and a [delta]15 desaturase during embryogenesis. Developing early to mid-cotyledonary MD embryos at 16 to 19 d in culture were treated with 10 [mu]M hormone/metabolite for 4 d. At various times during incubation, embryos and medium were analyzed to determine levels of hormone/metabolite, VLCMFAs, and oleosin or [delta]15 desaturase transcripts. The VLCMFAs, 20:1 and 22:1, primarily in triacylglycerols, increased by 200% after 72 h in the presence of (+)-ABA and 8[prime]-OH ABA relative to the control. In contrast, treatment with PA for 72 h had little effect (20% increase) on the level of VLCMFAs. The first 24 to 72 h of (+)-ABA treatment were critical in the induction of VLCMFA biosynthesis, with 8[prime]-OH ABA lagging slightly behind (+)-ABA in promoting this response. The accumulation of VLCMFAs was positively correlated with an increase in elongase activity. (+)-ABA and its 8[prime]-OH ABA metabolite induced the accumulation of a 19-kD oleosin transcript within 2 to 4 h in culture. In addition, both (+)-ABA and 8[prime]-OH ABA induced the same level of [delta]15 desaturase transcript by 8 h. PA had no effect on the induction of either oleosin or [delta]15 desaturase transcripts. To our knowledge, this is the first report of the biological activity of 8[prime]-OH ABA and of stimulatory effects of (+)-ABA and 8[prime]-OH ABA on lipid and oleosin biosynthesis.

Canine model of acute aortic rupture: treatment with percutaneous delivery of a covered Z stent--work in progress.

PURPOSE: To develop a percutaneous treatment for aortic rupture with use of a covered intraluminal stent. MATERIALS AND METHODS: A transmural tear was created percutaneously in the thoracic aorta in six dogs with use of a 4-mm angioplasty balloon. Gianturco Z stents were covered with polytetrafluoroethylene, loaded into a 14-F sheath, and advanced through the femoral artery to the site of injury. Within 2 minutes after initiation of the injury, the stent was deployed. Homologous canine blood was given during the procedure. Dogs that survived 24 hours were then killed. RESULTS: The first stent did not expand completely, and the dog died in 1 hour. At necropsy, the first two dogs (1-hour and 8-hour survival) had a large left hemothorax and extensive periaortic hematoma, indicating intrathoracic exsanguination. The next four dogs were treated with a modified stent and survived 2 hours (n = 1), 8 hours (n = 1), and 24 hours (n = 2). At necropsy hemothorax did not exceed 15 mL, and periaortic hematomas were small. The cause of death in the two early casualties with the modified stent is uncertain. There were no signs of spinal cord injury despite occlusion of three pairs of intercostal arteries. CONCLUSION: The covered Z stent (in its modified form) tamponaded the aortic tear, preventing exsanguination. Long-term studies of biocompatibility of this device appear justified.

Staging of fixation and retrievability of Greenfield filters.

PURPOSE: The purpose of this study was to determine the retrievability of the Greenfield filter, to characterize fixation, and to evaluate the mechanical function of a new retrieval unit. METHODS: Stainless steel, titanium, and two prototype Greenfield filters (n = 82) were placed in 15 sheep at multiple sites and retrieved acutely, and 7, 14, and 21 days after placement. The animals were killed, and appropriate tissues were submitted for histopathologic evaluation. RESULTS: Eighty-two percent of all filters were retrieved. Two animals died during the procedure of cardiac tamponade. Retrieval was easiest immediately after placement, but it was least successful from the right atrium and associated with the highest incidence of damage. By 21 days, the intima around the filter hooks had thickened with myointimal hyperplasia and variable amounts of endothelial regeneration. Guide wire-hook modification was used to improve filter capture. CONCLUSIONS: All models of the Greenfield filter can be retrieved 14 to 21 days after placement, although there is high risk to retrieval from the right atrium and ventricle. The long-term safety of the Greenfield filter in man makes it difficult to justify removal in any but exceptional cases.

Aortobronchial fistula 13 years following repair of aortic transection.

We describe a 56-year-old man with the new onset of hemoptysis, increasing in frequency and magnitude, initially diagnosed and treated as pulmonary embolism. Bronchoscopy, computed tomography, and thoracic aortography were performed twice before the diagnosis was made. Thirteen years previously, the patient underwent thoracic aortic interposition graft placement for aortic laceration as a result of a motor vehicle accident. The second aortogram demonstrated a small pseudoaneurysm at the expected proximal graft suture line. Aortobronchial fistula, a rare cause of hemoptysis, was diagnosed. The patient underwent successful resection of the graft and placement of a new dacron interposition graft. All cultures, including blood, sputum, and operative specimen cultures, were negative. The patient is alive and well 1 year following surgery.

Aortic cobwebs: an anatomic marker identifying the false lumen in aortic dissection--imaging and pathologic correlation.

PURPOSE: To describe and estimate the frequency of fibroelastic cords or bands projecting from the false lumen wall ("aortic cobwebs") in acute and chronic dissections. MATERIALS AND METHODS: Pathologic specimens (n = 23), routine magnetic resonance (MR) images (n = 27), and intravascular (n = 5) and transesophageal (n = 3) ultrasound (US) images from 43 patients with aortic dissection were reviewed, and the presence and configuration of cobwebs were noted. RESULTS: Aortic cobwebs usually bridge the junction of the dissection flap with the outer wall of the false lumen (the line of dissection) but occasionally project like small tendrils from the false lumen wall remote from the line of dissection. Cobwebs were found in 17 of 23 pathologic specimens and on six of 27 MR images, two of five intravascular US scans, and one of three transesophageal US scans. CONCLUSION: Aortic cobwebs most likely represent residual ribbons of media that have been incompletely sheared from the aortic wall during the dissection process. As such, they can serve as an anatomic marker of the false lumen. They are occasionally seen on routine aortic images and may, therefore, prove useful for orientation during percutaneous or surgical interventional procedures to relieve ischemic complications of aortic dissection.

Inflammatory and procoagulant mediator interactions in an experimental baboon model of venous thrombosis.

Theoretic and in vitro evidence suggests that thrombosis and inflammation are interrelated. The purpose of the present study was to define the relationship between inflammation and deep venous thrombosis (DVT) in an in vivo model. Initiation of DVT was accomplished by administration of antibody to protein C (HPC4, 2 mg/kg) and tumor necrosis factor (TNF, 150 micrograms/kg); stasis; and subtle venous catheter injury. Thrombosis was assessed by thrombin-antithrombin assay (TAT), 125I-fibrinogen scanning (scan) over both the proximal and distal iliac veins, and ascending venography. Cytokines TNF, interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1), and interleukin-8 (IL-8) were measured along with differential white blood cell counts, platelet counts, fibrinogen (FIB), and erythrocyte sedimentation rates (ESR). Baboon pairs were sacrificed on day 3 (T + 3d), T + 6d, and T + 9d and veins removed. All animals developed inferior vena cava and left iliofemoral DVT by venography; no right DVT was found. TAT was elevated by T + 1hr and peaked at T + 3hrs. Left iliofemoral DVT was found at T + 1hr by scan and reached a 20% uptake difference between the affected left and nonaffected right side at T + 3hrs. TNF peaked at T + 1hr; MCP-1 peaked at T + 6hrs; IL-8 and IL-6 peaked on T + 2d; all cytokines declined to baseline. TNF and TAT elevations were found to correlate with all cytokines; elevations in IL-8 were correlated with elevations in MCP-1 and IL-6 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the adrenalytic activity of mitotane and a methylated homolog on normal adrenal cortex and adrenal cortical carcinoma.

Mitotane is an important adrenalytic drug for the treatment of adrenal cancer whose use is limited by toxicity. Reports from another laboratory indicated that a methylated homolog of Mitotane (Mitometh) tested in guinea pigs possessed comparable adrenalytic activity but was less toxic than Mitotane. This observation prompted us to undertake a comparative study of these two drugs on the basis that Mitometh may be a superior agent for the treatment of adrenal cancer. Preliminary studies in guinea pigs failed to show a significant adrenalytic effect for either Mitotane or Mitometh. Thus, we extended the study to 13 mongrel dogs weighing 12-15 kg that were treated daily with Mitometh or Mitotane (50-100 mg/kg) for 6 or 12 days. Cortisol decreased to undetectable levels and adrenocorticotropic hormone (ACTH) rose to 10 times the baseline levels within 72 h in Mitotane-treated animals. Despite the achievement of similar drug levels, Mitometh treatment in dogs failed to suppress cortisol or increase ACTH. To determine whether these differences were due to differences in bioavailability, we measured the relative concentration of Mitotane and Mitometh in homogenates of adrenal cortex obtained from Mitotane- and Mitometh-treated dogs. The adrenal concentration of Mitometh determined in Mitometh-treated dogs was 5 times higher than the concentration of Mitotane measured in Mitotane-treated animals. Whereas the adrenal glands of Mitotane-treated dogs showed hemorrhage and necrosis, the Mitometh-treated animals showed no adrenal damage. Despite the lack of adrenalytic activity, Mitometh maintained its toxicity as demonstrated by microscopic evidence of hepatic necrosis and an increase in hepatic enzymes. The adrenalytic effects of both agents was also studied in vitro using a human functioning adrenal cortical carcinoma cell line, NCI-H295. Whereas Mitotane strongly suppressed cell growth, Mitometh had a weaker effect. We conclude that Mitometh is not likely to be effective in the therapy of adrenal cancer. Moreover, the results of this study are supportive of the view that metabolic transformation of Mitotane is in some way linked to its adrenalytic action.

Conservative management of bilateral massive edema of the ovary. A case report.

A case of bilateral massive ovarian edema with unilateral ovarian torsion is reported. Following surgical removal of the adnexa with the torsion, the edema of the opposite ovary resolved with oral contraceptive therapy. This has not been previously reported. This case is instructive because the nodular appearance and yellow color of the ovaries and the presence of yellow ascitic fluid could lead to an erroneous diagnosis of malignancy, resulting in performance of a more radical surgical procedure than is necessary. A review of the literature and the unusual nature of this lesion indicates the need for caution in diagnosis and management.

Creation of reentry tears in aortic dissection by means of percutaneous balloon fenestration: gross anatomic and histologic considerations.

PURPOSE: To study the safety and efficacy of percutaneous fenestration in aortic dissection, transmural tears in canine and human aortae were created with conventional angioplasty balloons. MATERIALS AND METHODS: Tears created in the aortae of five living dogs were compared with tears created in postmortem specimens. Percutaneous fenestration was performed in a woman with acute type I dissection and ischemic hepatitis who died in multisystem failure, and the balloon tear was documented at autopsy. Additional tears in the human aorta were studied in necropsy specimens of normal, Marfanoid, atherosclerotic, and acutely and chronically dissected thoracic and abdominal aortae. RESULTS: In the canine aorta, transmural balloon tears resulted in rapid death of all five animals, and the tears were approximately 10% longer than tears created post mortem with the same balloon. In human aortic specimens, most transmural and all transseptal tears were linear and were oriented nearly perpendicular to the longitudinal axis of the aorta. Tears that were initiated near calcified plaques or large aortic branches extended in unpredictable directions. The transverse orientation of the tears coincided with the long axis of smooth muscle cells in the media of the intact aorta or the dissection septum. CONCLUSION: Percutaneous balloon fenestration, when performed in areas of the aorta relatively free of atherosclerosis, results in transverse tears in the aortic dissection septum. Percutaneous fenestration of the aortic dissection septum appears feasible and should be considered as a treatment option in carefully selected cases of aortic dissection with ischemic complications. A final conclusion regarding the safety and efficacy of percutaneous fenestration undertaken to relieve organ ischemia requires further clinical experience.

Shock-wave thrombus ablation, a new method for noninvasive mechanical thrombolysis.

Successful experimental and clinical experience with thrombus ablation has been attained with high-power acoustic energy delivered in a catheter. The goal of this study was to investigate the feasibility of noninvasive thrombus ablation by focused high-power acoustic energy. The source for high-power acoustic energy was a shock-wave generator in a water tank equipped with an acoustic lens with a fixed focal point at 22.5 cm. Thrombus was prepared in vitro, weighed (0.24 +/- 0.08 g), and inserted in excised human femoral artery segments. The arterial segments wer ligated, positioned at the focal point and then randomized into either test (n = 8) or control (n = 7). An x-ray system verified the 3-dimensional positioning of the arterial segment at the focal point. A 5 MHz ultrasound imaging system continuously visualized the arterial segment at the focal point before, during and after each experiment. The test segments were exposed to shock waves (1,000 shocks/24 kv). The arterial segment content was then flushed and the residual thrombus weighed. The arterial segment and thrombus were fixed and submitted to histologic examination. The test group achieved a significant ablation of thrombus mass (0.25 +/- 0.15 vs 0.07 +/- 0.003 g; p = 0.0001) after application of shock waves. Arterial segments showed no gross or microscopic damage. Ultrasound imaging revealed a localized (1.9 +/- 0.5 cm2), transient (744 +/- 733 ms), cavitation field at the focal point at the time of application of focused shock waves. Thus, focused high-power acoustic energy can effect noninvasive thrombus ablation without apparent damage to the arterial wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoxia-induced bacterial translocation in the puppy.

Because hypoxia is one of the most common major stresses to which a neonate is exposed, we postulated that it alone might be the cause of intestinal bacterial translocation, which could be the underlying etiology of neonatal sepsis. An animal model, in which hypoxia is the sole stress, was developed in our laboratory and tested in 18 puppies to determine the effect of hypoxia and reoxygenation on intestinal bacterial translocation. In group I (n = 8), following laparotomy and cannulation of the superior mesenteric vein (SMV), the FIO2 was decreased from 21% to 9% for 90 minutes followed by reoxygenation at 21% for 120 minutes. The abdomen was closed and the animals were allowed to recover. After 24 hours the mesenteric lymph nodes (MLNs), spleen, and liver were harvested for bacterial determination and the ileum and jejunum for histological evaluation. Group II (n = 7) was treated the same as group I with the FIO2 maintained at 21%. Group III (n = 3) animals were killed, without intervention, for bacterial analysis. In group I, the systemic PO2 decreased by 75%, SMV PO2 decreased by 64%, and oxygen delivery to the small bowel decreased by 80% in comparison with group II. The mean arterial pressure and cardiac output were not significantly different between group I and group II; however, the mucosal blood flow was decreased by 60% (P less than .001) in group I. Arterial and SMV blood lactic acid levels were unchanged in group I in comparison with group II, suggesting that anaerobic metabolism was not initiated in the splanchnic circulation during hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Intramural methotrexate therapy for the prevention of neointimal thickening after balloon angioplasty.

OBJECTIVES: The study was performed to test the hypothesis that high local, intramural concentrations of antineoplastic agents at the site of balloon injury inhibit vascular smooth muscle cell proliferation without systemic toxicity. BACKGROUND: The predominant mechanism for recurrent stenosis after coronary balloon angioplasty is neointimal thickening due to medial smooth muscle cell proliferation. The clinical use of potent antiproliferative agents to prevent restenosis has been limited by the potential for severe systemic side effects. Local therapy with these agents may be effective and free of systemic complications. METHODS: After bilateral balloon angioplasty of the carotid arteries of 14 juvenile farm pigs, the dilated arterial segments were treated locally with methotrexate (6.25 mg/ml, total dose 25 mg) or 0.9% saline solution through a perforated balloon catheter. The animals were then killed 30 days after balloon injury to determine the effects of this therapy on neointimal thickness. In an additional six animals, tritium-labeled methotrexate was used to determine the concentration and duration of detectability of methotrexate in the wall of the treated arteries and in the systemic circulation. RESULTS: Two hours after drug instillation the concentration of labeled drug was greater than 1,000-fold greater in the wall of the treated artery than in circulating blood, and this ratio remained between 50 and 100 for at least 7 days. Despite this difference, the mean intimal thickness 30 days after the procedure was similar in the 10 methotrexate-treated arteries and the 18 saline-treated arteries (59 +/- 30 vs. 56 +/- 25 microns, p = 0.6). The morphologic appearance of the neointima was similar in each group and suggested an important role for mural thrombus in the genesis of the intimal thickening. CONCLUSIONS: Treatment with intramural methotrexate, delivered through a perforated balloon catheter at the selected concentration and total dose, failed to prevent intimal thickening after balloon injury. Nonetheless, the perforated balloon catheter appears to be a promising means of delivering a high local concentration of drugs with potentially life-threatening systemic side effects. The optimal concentrations and combinations of candidate drug therapies warrant further evaluation.

Design and testing of a high-flow autoperfusion catheter: an experimental study.

An autoperfusion catheter is similar to an angioplasty balloon catheter with side holes in the guide-wire lumen proximal to the balloon. When the balloon of the autoperfusion catheter is deployed and inflated in an artery, the guide wire is removed, and the hub of the guide-wire lumen is capped. The catheter then allows passive distal perfusion by using ambient pressure to drive blood into the guide-wire lumen, through the balloon, and out the end hole. This article discusses the requirements and constraints of a high-flow autoperfusion catheter, summarizes attempts to modify standard angioplasty catheters for use as an autoperfusion catheter, and describes the design and testing of a custom autoperfusion catheter capable of delivering approximately 3 mL/sec at physiologic pressures. In a model of canine acute renal artery occlusion lasting 90 minutes, the custom autoperfusion catheter provided marked protection from acute tubular necrosis compared with conventional percutaneous transluminal angioplasty catheters. The authors conclude that the high-flow autoperfusion catheter may be useful as a temporary stent in cases of rupture, dissection, or penetrating wounds involving large arteries.