Restoration Of Arterial Flow Research Articles

Preconditioning with selective autoretroperfusion: In vivo and in silico evidence of washout hypothesis.

Prompt reperfusion of coronary artery after acute myocardial infarction (AMI) is crucial for minimizing heart injury. The myocardium, however, may experience additional injury due to the flow restoration itself (reperfusion injury, RI). The purpose of this study was to demonstrate that short preconditioning (10min) with selective autoretroperfusion (SARP) ameliorates RI, based on a washout hypothesis. AMI was induced in 23 pigs (3 groups) by occluding the left anterior descending (LAD) artery. In SARP-b (SARP balloon inflated) and SARP-nb (SARP balloon deflated) groups, arterial blood was retroperfused for 10min via the great cardiac vein before releasing the arterial occlusion. A mathematical model of coronary circulation was used to simulate the SARP process and evaluate the potential washout effect. SARP restored left ventricular function during LAD occlusion. Ejection fraction in the SARP-b group returned to baseline levels, compared to SARP-nb and control groups. Infarct area was significantly larger in the control group than in the SARP-b and SARP-nb groups. End-systolic wall thickness was preserved in the SARP-b compared to the SARP-nb and control groups. Analyte values (pH, lactate, glucose, and others), measured every 2min during retroperfusion, suggest a "washout" effect as one important mechanism of action of SARP in reducing infarct size. With SARP, the values progressively approached baseline levels. The mathematical model also confirmed a possible washout effect of tracers. RI can be ameliorated by delaying restoration of arterial flow for a brief period of time while pretreating the infarction with SARP to restore homeostasis via a washout mechanism.

Combined percutaneous direct puncture of occluded artery - antegrade intervention for recanalization of below the knee arteries.

We aimed to assess the technical success of the combined percutaneous direct puncture of occluded artery - antegrade intervention technique, as well as the clinical effectiveness of treatment, on the basis of changes in the Rutherford classification. Between June 2015 and July 2018, 441 patients underwent endovascular recanalization due to lower limb peripheral arterial disease at our center. Of these, 18 patients (4%; 15 males, 3 females; mean age, 63.2 years) had failed antegrade recanalization and percutaneous retrograde access because of long segment occlusion, arterial rupture or dissection. Combined percutaneous direct puncture of occluded artery and antegrade approach was applied to these patients. Clinical follow-up examinations were performed at 1 month, 3 months, 6 months, and annually thereafter. The mean follow-up period was 22.8±10.9 months. The mean procedure time was 93.6±28.2 min. Technical success was achieved in 14 patients (78%). Complete restoration of arterial flow in the punctured vessel could not be achieved in 4 patients (22%). Minor complications occurred in 4 of 18 procedures (22%). Amputation-free survival and limb salvage rates (83.3% and 100%, respectively) were the same for 12 and 24 months. Technical success in lower limb peripheral arterial disease may be improved with the use of a combined percutaneous direct puncture of occluded artery - antegrade intervention, particularly for patients in whom other techniques are not a viable option.

How to deal with hepatic artery injury during pancreaticoduodenectomy. A systematic review

Operative injury to the hepatic artery is a serious complication of pancreaticoduodenectomy and guidelines to manage this complication are lacking. A systematic search performed in PubMed database identified eleven studies overall including 20 patients having sustained injury to the hepatic artery during pancreaticoduodenectomy (n=18) or total pancreatectomy (n=2). One further unpublished personal observation following pancreaticoduodenectomy was also included. Sixteen of 21 patients (76%) experienced serious complications including liver necrosis/abscess (n=14), acute liver failure (n=3), and biliary anastomotic dehiscence (n=6). Eleven patients (52%) were reoperated and 5 patients died (24%). Arterial injury was recognized and repaired immediately in five patients, four recovering uneventfully and one dying from acute liver failure (20%). In contrast delayed or conservative treatment in 16 patients was associated with serious early morbidity in 15 patients (94%), leading to death in 4 patients and late biliary complications in four others. Accidental interruption of arterial flow to the liver during pancreaticoduodenectomy often results in serious short and long-term consequences. Immediate restoration of arterial flow is indicated whenever technically feasible and may prevent early life-threatening complications as well as late biliary stenosis.

The Impact of Early Pelvic and Lower Limb Reperfusion and Attentive Peri-operative Management on the Incidence of Spinal Cord Ischemia During Thoracoabdominal Aortic Aneurysm Endovascular Repair

OBJECTIVE/BACKGROUND Spinal cord ischemia (SCI) is a devastating complication following endovascular thoracoabdominal aortic aneurysm (TAAA) repair. In an attempt to reduce its incidence two peri-procedural changes were implemented by the authors in January 2010: (i) all large sheaths are withdrawn from the iliac arteries immediately after deploying the central device and before cannulation and branch extension to the visceral vessels; (ii) the peri-operative protocol has been modified in an attempt to optimize oxygen delivery to the sensitive cells of the cord (aggressive blood and platelet transfusion, median arterial pressure monitoring >85 mmHg, and systematic cerebrospinal fluid drainage). METHODS Between October 2004 and December 2013, 204 endovascular TAAA repairs were performed using custom made devices manufactured with branches and fenestrations to maintain visceral vessel perfusion. Data from all of these procedures were prospectively collected in an electronic database. Early post-operative results in patients treated before (group 1, n = 43) and after (group 2, n = 161 patients) implementation of the modified implantation and peri-operative protocols were compared. RESULTS Patients in groups 1 and 2 had similar comorbidities (median age at repair 70.9 years [range 65.2-77.0 years]), aneurysm characteristics (median diameter 58.5 mm [range 53-65 mm]), and length of procedure (median 190 minutes [range 150-240 minutes]). The 30 day mortality rate was 11.6% in group 1 versus 5.6% in group 2 (p = .09). The SCI rate was 14.0% versus 1.2% (p < .01). If type IV TAAAs were excluded from this analysis, the SCI rate was 25.0% (6/24 patients) in group 1 versus 2.1% (2/95 patients) in group 2 (p < .01). CONCLUSION The early restoration of arterial flow to the pelvis and lower limbs, and aggressive peri-operative management significantly reduces SCI following type I-III TAAA endovascular repair. With the use of these modified protocols, extensive TAAA endovascular repairs are associated with low rates of SCI.

Editor's Choice – The Impact of Early Pelvic and Lower Limb Reperfusion and Attentive Peri-operative Management on the Incidence of Spinal Cord Ischemia During Thoracoabdominal Aortic Aneurysm Endovascular Repair

Spinal cord ischemia (SCI) is a devastating complication following endovascular thoracoabdominal aortic aneurysm (TAAA) repair. In an attempt to reduce its incidence two peri-procedural changes were implemented by the authors in January 2010: (i) all large sheaths are withdrawn from the iliac arteries immediately after deploying the central device and before cannulation and branch extension to the visceral vessels; (ii) the peri-operative protocol has been modified in an attempt to optimize oxygen delivery to the sensitive cells of the cord (aggressive blood and platelet transfusion, median arterial pressure monitoring >85mmHg, and systematic cerebrospinal fluid drainage). Between October 2004 and December 2013, 204 endovascular TAAA repairs were performed using custom made devices manufactured with branches and fenestrations to maintain visceral vessel perfusion. Data from all of these procedures were prospectively collected in an electronic database. Early post-operative results in patients treated before (group 1, n=43) and after (group 2, n=161 patients) implementation of the modified implantation and peri-operative protocols were compared. Patients in groups 1 and 2 had similar comorbidities (median age at repair 70.9 years [range 65.2-77.0 years]), aneurysm characteristics (median diameter 58.5mm [range 53-65mm]), and length of procedure (median 190 minutes [range 150-240 minutes]). The 30 day mortality rate was 11.6% in group 1 versus 5.6% in group 2 (p=.09). The SCI rate was 14.0% versus 1.2% (p<.01). If type IV TAAAs were excluded from this analysis, the SCI rate was 25.0% (6/24 patients) in group 1 versus 2.1% (2/95 patients) in group 2 (p<.01). The early restoration of arterial flow to the pelvis and lower limbs, and aggressive peri-operative management significantly reduces SCI following type I-III TAAA endovascular repair. With the use of these modified protocols, extensive TAAA endovascular repairs are associated with low rates of SCI.

Endovascular recanalization of infrapopliteal occlusions in patients with critical limb ischemia

Endovascular therapies are increasingly used for treatment of critical limb ischemia (CLI). Infrapopliteal (IP) occlusions are common in CLI, and successful limb salvage may require restoration of arterial flow in the distribution of a chronically occluded vessel. We sought to describe the procedural characteristics and outcomes of patients with IP occlusions who underwent endovascular intervention for treatment of CLI. All patients with IP interventions for treatment of CLI from 2006 to 2012 were included. Angiographic and procedural data were compared between patients who underwent intervention for IP occlusions vs IP stenosis. Restenosis was determined by Doppler ultrasound imaging. Limb salvage was the primary end point of the study. Additional end points included primary patency, primary assisted patency, secondary patency, occlusion crossing success, procedural success, and amputation-free survival. A total of 187 patients with CLI underwent interventions for 356 IP lesions, and 77 patients (41%) had interventions for an IP occlusion. Patients with an intervention for IP occlusion were more likely to have zero to one vessel runoff (83% vs 56%; P < .001) compared with interventions for stenosis. Compared with IP stenoses, IP occlusions were longer (118 ± 86 vs 73 ± 67 mm; P < .001) and had a smaller vessel diameter (2.5 ± 0.8 vs 2.7 ± 0.5 mm; P = .02). Wire crossing was achieved in 83% of IP occlusions, and the overall procedural success for IP occlusions was 79%. The overall 1-year limb salvage rate was 84%. Limb salvage was highest in the stenosis group, slightly lower in the successful occlusion group, and lowest in the failed occlusion group (92% vs 75% vs 58%, respectively; P = .02). Unsuccessfully treated IP occlusions were associated with a significantly higher likelihood of major amputation (hazard ratio, 5.79; 95% confidence interval, 1.89-17.7) and major amputation or death (hazard ratio, 2.69; 95% confidence interval, 1.09-6.63). Successful endovascular recanalization of IP occlusions can be achieved with guidewire and support catheter techniques in most patients. In patients selected for an endovascular-first approach for IP occlusions in CLI, this strategy can be successfully implemented with favorable rates of limb salvage.

Alexis Carrel, Rene Leriche, Jean Kunlin, and the history of bypass surgery

Alexis Carrel, Rene Leriche, Jean Kunlin, and the history of bypass surgery

Risk factors associated with early hepatic artery thrombosis after orthotopic liver transplantation - univariable and multivariable analysis

Hepatic artery thrombosis (HAT) is a serious complication in patients undergoing orthotopic liver transplantation (OLT). It is associated with a high graft loss and mortality rate. In this study, possible risk factors associated with early HAT (occurring within the first postoperative month) were evaluated using univariable and multivariable analyses. Nine-hundred-and-fourteen consecutive OLTs in our institution were examined by univariable and multivariable analyses. Early HAT occurred in 43 patients (4.7%). Graft number, abnormal donor arterial anatomy, bench arterial reconstruction, aortic conduit use, multiple anastomoses, reperfusion time (interval between portal vein reperfusion and restoration of arterial flow) and the number of units of blood received intraoperatively were significantly associated with early HAT in the univariable analysis(P<0.1). These variables were included in a multivariable regression model which showed that bench arterial reconstruction was associated with a fourfold risk of early HAT(P<0.0001), whereas each additional 10min delay in reperfusion was associated with a 27% increase in the risk of early HAT (P<0.04). The main risk factors associated with early HAT are abnormal arterial anatomy in the graft requiring bench reconstruction and a delay in arterial reperfusion. Early recognition of these factors, strict surveillance protocols with arterial Doppler and selective anticoagulation for patients at risk need to be evaluated prospectively.

QS331. Management of Vascular Injuries Associated With Knee Dislocations in the Obese Patient

Introduction: The management of injuries to the popliteal artery that occur as a result of traumatic knee dislocation focuses on timely restoration of arterial flow and stabilization of the orthopedic injury. In some cases, determining the order of repair can be challenging, especially when complex vascular and/or orthopedic injuries exist. In the obese patient, repair can be more complex and time-consuming, which can increase the chance for subsequent complications. Case Report: A 40-year-old obese male presented with severe pain in the right knee after twisting it while exiting a golf cart.

Minimally Invasive Revascularization Strategies for Chronic Lower Limb Ischemia

Lower extremity wounds resulting from ischemia are increasingly becoming a common indication for surgical revascularization. Techniques in minimally invasive vascular surgery for the treatment of lower extremity chronic ischemia have expanded rapidly in recent years. The current standard of care with which all new modalities should be compared is the restoration of arterial flow via direct arterial revascularization using the autogenous reversed saphenous vein that can yield limb salvage rates of approximately 95%. Percutaneous transluminal angioplasty and stenting (PTA/S), cryoplasty, catheter-directed atherectomy, laser-assisted PTA/S, drug-eluting stents, and subintimal angioplasty are emerging minimally invasive modalities used for the treatment of lower extremity ischemia. Early success rates using many of these techniques have been promising. The outcomes of randomized controlled trials with long-term follow-ups are needed to make confident remarks about the effectiveness of these techniques.

Clinical microbiological case: a patient with vascular risk factors, chest pain and fever

Please refer to the article on pages 55–56 of this issue to view the questions to which these answers refer. 1. An initial diagnosis of respiratory sepsis (pneumonia and/or empyma) was made, but the serohemorrhagic nature of the pleural effusion led to the clinical suspicion of active hemorrhage into the pleural cavity. When the CT scan of the thorax was performed, it showed a sacular aneurysm of the descending aorta with perianeurysmal hematoma and a massive hemorrhagic effusion with areas of different density in the pleural cavity. A few minutes later, the patient died in cardiovascular collapse, before surgical intervention was possible. Autopsy was not authorized. Salmonella enteritidis serotype D was isolated from blood and in pleural fluid cultures. The patient thus had a sacular mycotic aneurysm of the descending aorta which ruptured towards the pleural cavity, caused by S. enteritidis. Mycotic aneurysms (MAs) caused by Salmonella species have often been described, because of the propensity of this microorganism to infect vascular sites. Salmonella. enteritidis serotypes are the most frequently reported in Europe, e.g. in Spain [1], whereas S. cholerasuis and S. typhimurium are predominant in the USA [2]. Merkin et al. found only 14 cases of thoracic aortic aneurysms produced by Salmonella species in their study of cases recorded from 1950 to 1993, and S. enteritidis serotype D was the most frequent [3]. Any Salmonella serotype can produce bacteremia, and Cohen et al. reported that 25% of people over 50 years with salmonella bacteremia had endothelial infection, demonstrating the important role played by this microorganism in the pathogenesis of intravascular infections [4]. Nevertheless, reported cases of mycotic aneurysms caused by Salmonella are scarce, and the intrathoracic location in this case is exceptional. 2. A high index of suspicion is essential if the diagnosis of mycotic aneurysm is to be made, because initial symptoms are frequently non-specific and earlydiagnosis is important forpromptandsuccessful treatment [5]. The diagnosis can be established when there are appropriate clinical findings, such as high fever and chills, or symptoms related to the location of the aneurysm (back, shoulder or abdominal pain), along with recurrent bacteremia and the demonstration of aneurysmal dilatation of the aortic wall on a CT scan of the thorax. This last finding should be confirmed by aortography. Finally, the presence of cardiovascular risk factors or established arteriosclerotic disease also supports the diagnosis. Probably, the patient had repeated ruptures, coinciding with bacteremia, that were contained by perianeurysmal inflammatory activity. Such presumed intermittent bleeding areas explain the finding of areas of different density in the pleural cavity. Cases of relapsing rupture, contained by the blood itself or by other structures such as the parietal pleura, mediastinum or retroperitoneum, have also been described [6,7]. 3. The optimal treatment is surgical debridement of the aneurysm and the restoration of arterial flow by prosthetic reconstruction in situ or by extraanatomic bypass [8]. Prolonged administration of antibiotics is required, usually for more than 6 weeks, and several authors recommend lifelong antimicrobial therapy because of high relapse rates. However, despite early surgical intervention, development of new surgical techniques, and effective bactericidal antibiotics such as ampicillin, ciprofloxacin, or third-generation cephalosporins, the mortality rate in these patients remains as high as 75% [3,8–10]. Finally, although salmonella gastroenteritis is usually a self-limiting disease, and bacteremia develops in less than 5% of all patients, certain individuals are at increased risk of invasive infection, and may benefit from preventive antimicrobial therapy. Antimicrobial therapy should be considered for neonates, persons older than 50 years, and patients with immunosuppression, cardiac valvular or mural abnormalities, or prosthetic vascular grafts.

Use of Superficial Femoral Vein in the Treatment of Infected Aortoiliofemoral Prosthetic Grafts

Purpose: To assess the use of the superficial femoral vein for the reconstruction of the aortoiliofemoral sector in the treatment of prosthetic infections. Methods: From December 1995 to November 1999, 12 patients with infection involving a synthetic vascular prosthesis were submitted to thirteen surgical procedures involving partial or total resection of a synthetic vascular prosthesis and restoration of arterial flow with an in situ femoral vein. Results: The overall operative mortality rate was 15.3% (2 out of 3 patients who underwent total graft replacement and 0 out of 9 patients who underwent unilateral graft replacement). Major amputations related to the surgical procedures were performed in two cases (an 87.5% rate of limb salvage). The series was followed up on average for 22 months (range: 6–65 months). No patient presented clinically significant edema or signs of chronic venous insufficiency in the lower limbs used as donors of autogenous venous grafts. All surviving patients presented complete resolution of the infectious signs and symptoms and none of them presented late thrombosis of the venous graft. Conclusion: The use of the superficial femoral vein is a good surgical alternative for the treatment of prosthetic infections with minimal venous morbidity of the lower limbs used as venous graft donors. The autogenous venous grafts present good long-term patency and excellent adaptation to the aortoiliofemoral position.

Use of superficial femoral vein in the treatment of infected aortoiliofemoral prosthetic grafts

Purpose: To assess the use of the superficial femoral vein for the reconstruction of the aortoiliofemoral sector in the treatment of prosthetic infections. Methods: From December 1995 to November 1999, 12 patients with infection involving a synthetic vascular prosthesis were submitted to thirteen surgical procedures involving partial or total resection of a synthetic vascular prosthesis and restoration of arterial flow with an in situ femoral vein. Results: The overall operative mortality rate was 15.3% (2 out of 3 patients who underwent total graft replacement and 0 out of 9 patients who underwent unilateral graft replacement). Major amputations related to the surgical procedures were performed in two cases (an 87.5% rate of limb salvage). The series was followed up on average for 22 months (range: 6–65 months). No patient presented clinically significant edema or signs of chronic venous insufficiency in the lower limbs used as donors of autogenous venous grafts. All surviving patients presented complete resolution of the infectious signs and symptoms and none of them presented late thrombosis of the venous graft. Conclusion: The use of the superficial femoral vein is a good surgical alternative for the treatment of prosthetic infections with minimal venous morbidity of the lower limbs used as venous graft donors. The autogenous venous grafts present good long-term patency and excellent adaptation to the aortoiliofemoral position.

Reperfusion injury delays healing of intestinal anastomosis in a rat

BACKGROUND: Revascularization of ischemic bowel may induce further local tissue damage due to reperfusion injury. Therefore, we aimed to investigate the effect of ischemia-reperfusion injury on the healing of intestinal anastomosis in experimental models. METHODS: One hundred and two male Wistar rats were divided into three groups: a control group (group I, n = 23); an ischemia group (group II, n = 32), in which only the superior mesenteric artery (SMA) was occluded for 30 minutes; and a profound ischemia group (group III, n = 47), in which SMA was occluded as well as collateral vessels for 30 minutes. The pulsations were seen to return to marginal vessels and the bowels began to appear pinker and healthier in all groups following the restoration of arterial flow. Then, all animals underwent a 3-cm ileal resection and primary anastomosis, 10 cm proximal to the ileo-cecal valve. Within each group, animals were anesthetized either on the third or seventh postoperative days. Abdominal wound healing, intra-abdominal adhesions, anastomotic complications, anastomotic bursting pressure measurements, and bursting site were recorded. RESULTS: Statistically significant differences were detected in intraperitoneal adhesion scores in group II and III ( P <0.001). Anastomotic dehiscence was found in 2 of 23 (9%) in group I, 5 of 32 (16%) in group II, and 16 of 47 (34%) in group III ( P <0.001). On the third and seventh days, the median bursting pressures of the anastomosis were determined to be 42 mm Hg and 250 mm Hg in group I, 46 and 253 in group II, and finally 19 and 90 mm Hg in group III ( P <0.01). The burst occurred at the anastomoses in all animals tested on the third postoperative day, none in group I, 4 (28%) in group II, and 8 (67%) in group III on the seventh postoperative day ( P <0.005). CONCLUSION: The present study demonstrated that ischemia-reperfusion impairs anastomotic healing. Despite the fact that the intestines are well perfused and viable after revascularization, one must bear in mind that intestinal reperfusion may compromise anastomotic healing.

The Society for Vascular Surgery: Then and now

The Society for Vascular Surgery: Then and now

Acute Myocardial Ischemia: Effects of Reperfusion with Arterial Blood

Periods of severe ischemia of 15 minutes or less injure myocytes of the dog heart reversibly in that reperfusion of the affected tissue with arterial blood salvages all myocytes destined to die if the ischemia is not relieved. While the myocytes are ischemic, they develop numerous changes as a consequence of ischemic metabolism including depletion of approximately P and accumulation of glycolytic intermediates, H+, and the end-products of adenine nucleotide pool degradation. With restoration of arterial flow, aerobic respiration resumes. Lactate and other intermediates are reutilized or are washed to the systemic circulation. If the period of severe ischemia is extended to 40-60 minutes, the injury becomes irreversible. Such myocytes cannot be salvaged by reperfusion with arterial blood and are necrotic. When reperfused, irreversibly injured myocytes develop contraction-band necrosis and accumulate calcium phosphate. Although unproved, it is possible that some myocytes, alive at the time of reperfusion, may die as a consequence of successful reperfusion. This phenomenon is termed lethal reperfusion injury. Sublethal forms of reperfusion injury, such as stunning, also occur.

Nonresective Therapy for Abdominal Aortic Aneurysm in the High-Risk Patients—Case Reports

Three high-risk patients with an abdominal aortic aneurysm have been man aged with nonresective treatment, including ligation of femoral arteries and, in 2 cases, introduction of Gianturco-Wallace coils into the sac, to induce acute thrombosis of the AAA, and an axillo-bifemoral bypass for restoration of arte rial flow to the lower limbs. One patient died postoperatively. The literature on this alternative treatment is reviewed. It is stressed that there are a high mortality rate and a high incidence of serious and often lethal complications and that rupture of the aneurysm is not fully precluded. Thus noresective treatment of AAA has to be used with extreme precaution in high- risk patients.

Advances in the Management of Acute Popliteal Vascular Blunt Injuries

This report evaluates critical points in the management of 30 consecutive blunt traumatic popliteal vascular injuries. All arterial injuries were diagnosed both clinically and by Doppler and PVR examinations. Twenty-eight of the 30 arterial reconstructions required interposition bypass grafts, nine of which were PTFE and the remainder were autogenous saphenous veins. In 19 patients the distal anastomosis was made to the distal popliteal artery and in nine patients to the tibial-peroneal arteries. In ten patients in whom limb survival was threatened, the ischemic time was shortened by the use of temporary Silastic shunt for rapid restoration of arterial flow. Nine patients had associated venous injuries which were repaired. Nine of the first 14 patients required fasciotomy but the last 16 patients were treated with hypertonic mannitol and only two of them required fasciotomy. There were no amputations, but in four limbs there were functional losses. In spite of the more extensive damage of blunt trauma, prompt and aggressive management aided by vascular laboratory tests, indwelling shunt, and hypertonic mannitol is rewarded with preservation of limbs following acute popliteal vascular injuries.

Modification of myocardial ischemia in normal and hypertrophied hearts utilizing diastolic retroperfusion of the coronary veins

Myocardial infarction following coronary occlusion limits the effectiveness of emergency coronary artery bypass operations. We designed and evaluated a transvenously introduced balloon-tipped catheter and an electrocardiogram-activated pumping system for perfusing ischemic myocardium by retrograde pulsation of oxygenated blood into the coronary veins during diastole. Balloon deflation during systole allowed for normal venous drainage. Four groups of dogs (n = 26) were instrumented with sonomicrometry crystals and catheters to measure regional and global left ventricular function. Two groups of dogs had chronic left ventricular (LVH) produced by prior aortic banding (left ventricular mass 174 gm versus 115 gm for control dogs of equal body weight, p less than or equal to 0.05). The left anterior descending coronary artery (LAD) was occluded for 40 minutes; after 10 minutes left ventricular function was severely depressed in all groups (less than or equal to 0.05 compared to baseline). Groups 1 (normal left ventricle, n = 8) and 2 (LVH, n = 5) had no further therapy for the following 30 minutes. Groups 3 (normal left ventricle, n = 8) and 4 (LVH, n = 5) received 30 minutes of coronary vein retroperfusion (CVRP) 10 minutes following the LAD occlusion. CVRP restored 37% of systolic shortening, whereas there was no restoration of systolic shortening in control dogs (p less than or equal to 0.001). All other physiological and hemodynamic parameters including heart rate, cardiac output, aortic pressure, dP/dt, and left ventricular dilatation were normalized during CVRP while remaining severely depressed in control dogs (p less than or equal to 0.05). Following restoration of arterial flow at 40 minutes, 10 of 13 CVRP-treated dogs recovered normal left ventricular function while only two of 13 untreated dogs survived. CVRP offers a transvenous approach for modifying myocardial ischemia prior to emergency coronary artery bypass grafting.

Pyelorenal Backflow in Normal and Ischemic Rabbit Kidneys

Pyelorenal backflow during retrograde pyelography was studied in 68 kidneys of anesthetized rabbits. Thirty-three of the experiments were performed during or shortly after temporary renal arterial clamping. Pyelosinous backflow was observed in 67 and pyelovenous backflow in 65 of the 68 kidneys, occurring at an average intrapelvic pressure of 70 mmHg. This was true in intact kidneys and during arterial occlusion. Intrarenal backflow--intrusion of contrast material into the renal parenchyma--could be produced in only one of 35 experiments on intact kidneys, and occurred at an intrapelvic pressure of 119 mmHg. During arterial clamping, intrarenal backflow was observed in eight of nine experiments, occurring at intrapelvic pressures of about 70 mmHg. After removal of the clamp, intrarenal backflow was less frequent with shorter periods of arterial clamping and longer time between restoration of arterial flow before pyelography. Subcapsular extravasation of the medium with total blurring of the kidneys shadow and a prompt fall in intrapelvic pressure was the ultimate result of prolonged and extreme overdistension of the renal pelvis. It occurred at an average intrapelvic pressure of 80 mmHg. Histologic examination revealed tears in the fornix of the pelvic cavity in cases with pyelosinous backflow. If intrarenal backflow was present, there were tears leading from the pelvic cavity into the renal parenchyma. Supplementary experiments using a contrast material that could be demonstrated histologically (barium sulfate with gelatin) showed that the contrast filled the intertubular capillaries and venules. There was no evidence of backflow through the canalicular route.