Can we safely expand the donation after circulatory death donor heart pool by extending the donor age limit?

OBJECTIVE: This study evaluates the impact of donor age on outcomes following donation after circulatory death heart transplantation. METHODS: The United Network for Organ Sharing registry was queried to analyze adult recipients who underwent isolated donation after circulatory heart transplantation from January 1, 2019, to September 30, 2023. The cohort was stratified into 2 groups according to donor age, where advanced donor age was defined as 40 years or more. Outcomes were 90-day and 1-year post-transplant survival. Propensity score matching was performed. Subgroup analysis was performed to evaluate the effects of recipient age on 90-day survival among the recipients with advanced-age donors. RESULTS: A total of 994 recipients were included in the study period, and 161 patients (17.1%) received allografts from advanced-age donors. During the study period, the annual incidence of donation after circulatory heart transplantation with advanced-age donors substantially increased. The recipients with advanced-age donors had similar 90-day and 1-year post-transplant survivals compared with the recipients with younger donors. The comparable 90-day survival persisted in a propensity score-matched comparison. In the subgroup analysis among the recipients with advanced-age donors, the recipients aged 60 years or more had significantly reduced 90-day survival compared with the recipients aged less than 60 years. CONCLUSIONS: The use of appropriately selected donation after circulatory donors aged 40 years or more has similar survival compared with that of younger donors. With careful candidate risk stratification and selection, consideration of using donation after circulatory donors aged more than 40 years may further ameliorate ongoing organ shortage with comparable early post-transplant outcomes.

Outcomes of Impella 5.0 and 5.5 for cardiogenic shock: A single-center 137 patient experience.

BACKGROUND: This study evaluated the outcomes of patients with cardiogenic shock (CS) supported with Impella 5.0 or 5.5 and identified risk factors for in-hospital mortality. METHODS: Adults with CS who were supported with Impella 5.0 or 5.5 at a single institution were included. Patients were stratified into three groups according to their CS etiology: (1) acute myocardial infarction (AMI), (2) acute decompensated heart failure (ADHF), and (3) postcardiotomy (PC). The primary outcome was survival, and secondary outcomes included adverse events during Impella support and length of stay. Multivariable logistic regression was performed to identify risk factors for in-hospital mortality. RESULTS: One hundred and thirty-seven patients with CS secondary to AMI (n = 47), ADHF (n = 86), and PC (n = 4) were included. The ADHF group had the highest survival rates at all time points. Acute kidney injury (AKI) was the most common complication during Impella support in all 3 groups. Increased rates of AKI and de novo renal replacement therapy were observed in the PC group, and the AMI group experienced a higher incidence of bleeding requiring transfusion. Multivariable analysis demonstrated diabetes mellitus, elevated pre-insertion serum lactate, and elevated pre-insertion serum creatinine were independent predictors of in-hospital mortality, but the etiology of CS did not impact mortality. CONCLUSIONS: This study demonstrates that Impella 5.0 and 5.5 provide effective mechanical support for patients with CS with favorable outcomes, with nearly two-thirds of patients alive at 180 days. Diabetes, elevated pre-insertion serum lactate, and elevated pre-insertion serum creatinine are strong risk factors for in-hospital mortality.

The Clinical Significance of Unplanned Coronary Artery Bypass Grafting in Aortic Root Replacement.

OBJECTIVES: Unexpected coronary artery bypass grafting (CABG) is occasionally required during aortic root replacement (ARR). However, the impact of unplanned CABG remains unknown. DESIGN: A single-center, retrospective observational study. SETTING: At university-affiliated tertiary hospital. PARTICIPANTS: All patients who underwent ARR from 2011 through 2022. INTERVENTIONS: Aortic root replacement with or without unplanned CABG. MEASUREMENTS AND MAIN RESULTS: A total of 795 patients underwent ARR. Among them, 131 (16.5%) underwent planned concomitant CABG, and 34 (4.3%) required unplanned CABG. The most common indication of unplanned CABG was ventricular dysfunction (33.3%), followed by disease pathology (25.6%), anatomy (15.4%), and surgical complications (10.3%). A vein graft to the right coronary artery was the most commonly performed bypass. Infective endocarditis and aortic dissection were observed in 27.8% and 12.8%, respectively. Prior cardiac surgery was seen in 40.3%. The median follow-up period was 4.3 years. Unplanned CABG was not associated with operative mortality (odds ratio [OR] 1.54, 95% CI 0.33-7.16, p = 0.58) or long-term mortality (hazard ratio 0.91, 95% CI 0.44-1.89, p = 0.81). Body surface area smaller than 1.7 was independently associated with an increased risk of unplanned CABG (OR 4.51, 95% CI 1.85-11.0, p < 0.001). CONCLUSIONS: Unplanned CABG occurred in 4.3% of patients during ARR, but was not associated with operative mortality or long-term mortality. A small body surface area was a factor associated with unplanned CABG.

Midterm Outcomes After Aortic Valve Neocuspidization (Ozaki Procedure) in Adults.

BACKGROUND: Trileaflet aortic valve neocuspidization (AVN) using autologous pericardium (Ozaki procedure) is an emerging surgical treatment option for aortic valve diseases. Although excellent results have been reported from Japan, data pertaining to its use in the United States are sparse. METHODS: All adult patients who underwent AVN (AVN group) or surgical aortic valve replacement (SAVR) with a bioprosthetic valve (SAVR group) between 2015 and 2022 were identified. Propensity score matching was used to adjust the baseline characteristics between the 2 groups. RESULTS: A total of 101 patients underwent AVN, and 1816 patients underwent SAVR with a bioprosthetic valve. None in the AVN group required conversion to SAVR. Before matching, mean age in the AVN group was 68.5 ± 8.8 years, and 56 patients (55.4%) underwent concomitant procedures. Preoperatively, 3 (3%) had endocarditis. Bicuspid valve was observed in 38 (38.4%). None died at 30 days in the AVN group. The median follow-up duration was 3.2 years. After propensity score matching, the expected survival and freedom from at least moderate aortic regurgitation at 5 years was 91.7% ± 3.1% and 97.6% ± 1.7%, respectively. Propensity score matching yielded 77 patients in each group. The Kaplan-Meier curve demonstrated equivalent survival at 5 years between the 2 groups (P = .95). Additionally, freedom from at least moderate aortic regurgitation was comparable at 5 years (P = .23). CONCLUSIONS: AVN can be safely performed for a variety of aortic valve diseases, with or without concomitant operations. AVN demonstrated similar midterm outcomes compared with SAVR with a bioprosthetic valve in the United States adult population.

ISMICS Consensus Conference and Statements of Randomized Controlled Trials of Off-Pump Versus Conventional Coronary Artery Bypass Surgery.

OBJECTIVE: At this consensus conference, we developed evidence-informed consensus statements and recommendations on the practice of off-pump coronary artery bypass graft (OPCAB) by systematically reviewing and performing meta-analysis of the randomized controlled trials (RCTs) comparing OPCAB and conventional coronary artery bypass (CCAB). METHODS: All RCTs of OPCAB versus CCAB through April 2013 were screened, and 102 relevant RCTs (19,101 patients) were included in a systematic review and meta-analysis (15 RCTs of 9551 high-risk patients; and 87 RCTs of 9550 low-risk patients) in accordance with the Cochrane Collaboration and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology. Consensus statements for the risks and benefits of OPCAB surgery in mortality, morbidity, and resource use were developed based on best available evidence. RESULTS: Compared to CCAB, it is reasonable to perform OPCAB to reduce risks of stroke [class IIa, level of evidence (LOE) A], renal dysfunction/failure (class IIa, LOE A), blood transfusion (class I, LOE A), respiratory failure (class I, LOE A), atrial fibrillation (class I, LOE A), wound infection (class I, LOE A), ventilation time, and ICU and hospital length of stay (class I, LOE A). However, OPCAB may be associated with a reduced number of grafts performed (class I, LOE A) and with diminished graft patency (class IIa, LOE A, with increased coronary reintervention at 1 year and beyond (class IIa, LOE A), as well as increased mortality at a median follow-up of 5 years (class IIb, LOE A). CONCLUSIONS: OPCAB compared with CCAB may improve outcomes in the short-term (stroke, renal dysfunction, blood transfusion, respiratory failure, atrial fibrillation, wound infection, ventilation time, and length of stay). However, over the longer-term, OPCAB may be associated with reduced graft patency, and increased risk of cardiac re-intervention and death.

Robotically assisted hybrid coronary revascularization: does sequence of intervention matter?

OBJECTIVE: Hybrid coronary revascularization (HCR) is a treatment strategy for the revascularization of multivessel coronary disease that combines the advantages of both minimally invasive surgical techniques and percutaneous coronary intervention (PCI). The optimal sequence by which revascularization should be accomplished has not been determined. We investigated clinical outcomes in a series of patients planned for HCR via robotically assisted totally endoscopic coronary artery bypass (TECAB) and standard PCI based on revascularization sequence. METHODS: A total of 238 patients planned for HCR between 2001 and 2011 were divided into three groups based on treatment sequence: (a) TECAB before PCI, (b) PCI before TECAB, and (c) same-session procedure. Multiple procedural and clinical end points before discharge and up to 2 years after the procedure were compared between the three groups in an intention-to-treat analysis. Demographic features were reviewed to determine baseline differences between each group. RESULTS: Of the 238 patients, 175 (73.5%) underwent TECAB before PCI, 38 patients (16.0%) underwent PCI before TECAB, and 25 (10.5%) underwent a simultaneous revascularization procedure. At baseline, the patients undergoing TECAB before PCI were significantly older. There was a significantly higher incidence of previous myocardial infarction in the PCI-first group (P < 0.001). There was a significant difference in intensive care unit (ICU) length of stay (LOS), with shorter ICU stays in the simultaneous revascularization group (P = 0.031) and shorter hospital LOS in the PCI before TECAB group (P = 0.021). CONCLUSIONS: In conclusion, revascularization sequence did not dramatically impact clinical outcomes in our observational study. The patients undergoing PCI-first and same-session interventions had shorter hospital and ICU LOS compared with the patients undergoing surgery first. Our findings suggest that no revascularization approach is arbitrarily superior and that revascularization sequence should be individualized on the basis of patient presentation and anatomical considerations.

Anesthetic management of robotically assisted totally endoscopic coronary artery bypass surgery (TECAB).

Over the last decade, TECAB has matured into a reproducible technique associated with low incidence of both mortality and morbidity, as well as superior quality of life, when compared with open CABG surgery. However, TECAB also is associated with important and specific challenges for the anesthesiology team, particularly with regard to the physiologic stresses of OLV, placement of special catheters, and induced capnothorax. As the technology supporting robotic surgery evolves and familiarity with, and confidence in, TECAB increases, the authors anticipate increasingly widespread use of these procedures in an increasingly fragile and problematic patient population who will require the support of a skilled and vigilant anesthesiology team.

Hybrid coronary revascularization using robotic totally endoscopic surgery: perioperative outcomes and 5-year results.

BACKGROUND: Hybrid coronary revascularization combines minimally invasive coronary artery bypass grafting and catheter-based interventions. This treatment option represents a viable alternative to both open multivessel coronary bypass surgery through sternotomy and multivessel percutaneous coronary intervention. The surgical component of hybrid coronary intervention can be offered in a completely endoscopic fashion using robotic technology. We report on one of the largest series to date. METHODS: From 2001 to 2011, 226 patients (age, 61 years [range, 31 to 90 years]; 77.0% male; EuroSCORE, 2 [range, 0 to 13]) underwent hybrid coronary interventions on an intention-to-treat basis. Robotically assisted procedures were performed using the daVinci, daVinci S, and daVinci Si surgical telemanipulation systems (Intuitive Surgical, Inc, Sunnyvale, CA) and included 147 single, 72 double, and 7 triple endoscopic coronary artery bypass grafting procedures. Surgery was carried out first in 160 cases (70.8%), percutaneous coronary intervention was carried out first in 38 cases (16.8%), and 28 patients underwent simultaneous operations in a hybrid operating room (12.4%). Drug-eluting stents were used in 70.0% of the patients. RESULTS: Hospital mortality was 3 of 226 patients (1.3%), and hospital stay averaged 6 days (range, 3 to 54 days). Patients walked outside 7 days (range, 3 to 97 days) postoperatively and performed general household work 14 days (range, 7 to 180 days) postoperatively. Full activity was resumed at 42 days (range, 7 to 720 days). Five-year survival was 92.9%, and 5-year freedom from major adverse cardiac and cerebral events was 75.2%. At 5 years, 2.7% of bypass grafts and 14.2% of percutaneous coronary intervention targets needed reintervention. CONCLUSIONS: Robotically assisted hybrid coronary intervention enables surgical treatment of multivessel coronary artery disease with minimal trauma. Perioperative results and intermediate-term outcomes meet the standards of open coronary artery bypass grafting. Recovery time is short, and reintervention rates are acceptable.

Robotically assisted coronary endarterectomy.

Robotic assistance has enabled coronary artery bypass surgery to be performed safely in a completely endoscopic fashion, but diffusely diseased target vessels may pose a technical challenge. We present a case in which coronary endarterectomy was performed on the left anterior descending coronary artery during a two-vessel totally endoscopic coronary artery bypass procedure. A 52-year-old woman presented with intermittent substernal pain. Preoperative studies showed diffuse disease in the left coronary artery system. Bilateral internal mammary arteries were harvested robotically using a skeletonized technique in a completely endoscopic fashion. Cardiopulmonary bypass was achieved via peripheral cannulation, and the heart was arrested with intermittent cold antegrade hyperkalemic blood cardioplegia delivered via an ascending aortic occlusion balloon catheter. The first obtuse marginal anastomosis was performed. The left anterior descending coronary artery was diffusely diseased and heavily calcified. An end-to-side anastomosis was attempted to the right internal mammary artery with unsatisfactory results. A localized coronary endarterectomy was performed, and an extended anastomosis was completed using the right internal mammary artery. The patient recovered uneventfully and was discharged home on postoperative day 6. Diffuse coronary artery disease was once thought to be a prohibitive challenge for minimally invasive coronary bypass procedures. This case demonstrates that local coronary endarterectomy is feasible and safe in robotic totally endoscopic coronary artery bypass surgery.

Leoligin, the major lignan from Edelweiss, inhibits intimal hyperplasia of venous bypass grafts.

AIMS: Despite the lower patency of venous compared with arterial coronary artery bypass grafts, approximately 50% of grafts used are saphenous vein conduits because of their easier accessibility. In a search for ways to increase venous graft patency, we applied the results of a previous pharmacological study screening for non-toxic compounds that inhibit intimal hyperplasia of saphenous vein conduits in organ cultures. Here we analyse the effects and mechanism of action of leoligin [(2S,3R,4R)-4-(3,4-dimethoxybenzyl)-2-(3,4-dimethoxyphenyl)tetrahydrofuran-3-yl]methyl (2Z)-2-methylbut-2-enoat, the major lignan from Edelweiss (Leontopodium alpinum Cass.). METHODS AND RESULTS: We found that leoligin potently inhibits vascular smooth muscle cell (SMC) proliferation by inducing cell cycle arrest in the G1-phase. Leoligin induced cell death neither in SMCs nor, more importantly, in endothelial cells. In a human saphenous vein organ culture model for graft disease, leoligin potently inhibited intimal hyperplasia, and even reversed graft disease in pre-damaged vessels. Furthermore, in an in vivo mouse model for venous bypass graft disease, leoligin potently inhibited intimal hyperplasia. CONCLUSION: Our data suggest that leoligin might represent a novel non-toxic, non-thrombogenic, endothelial integrity preserving candidate drug for the treatment of vein graft disease.

Everolimus attenuates neointimal hyperplasia in cultured human saphenous vein grafts.

OBJECTIVE: Neointimal hyperplasia is the first step in a cascade leading to a reduced patency rate of saphenous vein grafts in comparison to arterial grafts in coronary artery bypass grafting. Using cultured human saphenous vein grafts as a model for coronary artery bypass grafting, we investigated if the mammalian target of rapamycin inhibitor everolimus attenuates neointimal hyperplasia. METHODS: Saphenous vein grafts from 10 patients undergoing coronary artery bypass grafting were processed as follows: from each patient, one segment served as baseline control at day 0. Two segments were cultured in a neointimal hyperplasia model separately. One received no treatment and the other everolimus (1 microM). All vein grafts underwent histomorphometric analysis, assessment of proliferation by Ki-67 immunostaining and quantification of phospho-S6 ribosomal protein using western blot analysis. RESULTS: Everolimus treatment resulted in reduced neointimal hyperplasia (thickness 3.7+/-1.2 microm) compared to untreated controls (10.1+/-2.5 microm, p=0.008). The intima/intima+media-ratio was reduced in the everolimus group (0.10+/-0.02) compared to untreated controls (0.24+/-0.07, p=0.008). The number of Ki-67 positive proliferating cells in everolimus treated vein grafts (15+/-7 cells/high power field) showed a tendency of reduction compared to untreated controls (36+/-20 cells/high power field, p=0.036). Finally, everolimus treatment resulted in downregulation of S6 ribosomal protein phosphorylation in comparison to untreated controls. CONCLUSION: Everolimus is able to reduce neointimal proliferation in cultured human saphenous vein grafts by inhibition of the mammalian target of rapamycin, even though different transfection methods are to be evaluated for a clinical application in coronary artery bypass grafting.

Intra-aortic Filtration in Cardiac Surgery: An Effective Method to Reduce Neurologic Injury in High-Risk Patients.

Cardiac surgery is associated with a significant risk of adverse outcomes, particularly neurologic and renal. Embolic events are the primary source of these deleterious consequences. Intraaortic filtration is the only current technology shown to effectively capture particulates released during cardiac procedures and decrease morbidity and mortality. Although most surgical candidates may potentially benefit from intraaortic filtration, some patients are more likely to experience improved outcomes. Based on the evidence reported in the literature and the extensive experience of the authors, the following opinion details the authors' rationale and recommendations for patient selection for intraaortic filtration during cardiac surgery.

Diagnostic accuracy of cardiac 64-slice computed tomography in detecting atrial thrombi. Comparative study with transesophageal echocardiography and cardiac surgery.

OBJECTIVES: Atrial thrombi are a potential source for cerebral and peripheral emboli. Objective of this study was to evaluate the diagnostic accuracy of 64-slice cardiac computed tomography (CT) for detection of atrial thrombi in comparison with transesophageal echocardiography (TEE) and cardiac surgery. MATERIAL AND METHODS: Sixty-four patients were examined with ECG-gated multidetector CT coronary or pulmonary vein angiography. All patients underwent TEE. Cardiac surgery was performed in 31 patients. The Hounsfield units (HU) of atrial lesions were measured. RESULTS: The diagnostic accuracy of 64-slice CT for the detection of atrial thrombi was 77%: sensitivity 100% (9/9), specificity 73% (40/55), positive predictive value (PPV) 38% (9/24), and negative predictive value (NPV) 100% (40/40). All 15 false positive (FP) findings by CT were located in the left atrial appendage (LAA). Four characteristic imaging features suggesting incomplete filling of the LAA were noted in FP: "hypostatic layering," 5/15 (33%); "flow phenomenon," 9/15 (60%); "HU-run-off," 8/15 (53%); higher intralesional HU in FP when compared with thrombi (153.8 HU +/- 71 vs. 46.6 HU +/- 10; P < 0.0001). The diagnostic accuracy of CT in detecting atrial thrombi improved significantly (P = 0.03) to 86% after defining "typical filling defects" as "flow phenomenon/>180 HU" (sensitivity 100%; specificity 84%; PPV 50%; NPV 100%). On receiver operating curve (ROC) analysis, a threshold of 60.7 HU showed a specificity of 100% and a sensitivity of 86.7% to distinguish between FP and thrombi. CONCLUSIONS: Cardiac ECG-gated 64-slice CT is accurate to exclude atrial thrombi, which can be applied eg, in patients before radiofrequency (RF) ablation. Left atrial appendage "filling defects" cause a high number of false positive findings, and there are radiologic features, which are helpful to differentiate them from true thrombi.

64-MDCT for diagnosis of aortic regurgitation in patients referred to CT coronary angiography.

OBJECTIVE: In clinical practice, 64-MDCT coronary angiography is increasingly being used for exclusion of coronary artery disease. Therefore, the purpose of this study was to evaluate whether aortic valve regurgitation can be diagnosed with 64-MDCT in comparison with transthoracic echocardiography. MATERIALS AND METHODS: Eighty-one consecutive patients were examined with ECG-gated CT coronary angiography using image reconstruction during end-diastole. The diagnostic criterion for aortic valve regurgitation by CT was an incomplete coadaptation of aortic valve leaflets, the central aortic regurgitation area (ARA), which was quantified. All patients underwent transthoracic echocardiography using semiquantitative grading of aortic valve regurgitation (i.e., mild, moderate, or severe). RESULTS: Of the 81 patients, 45 had aortic valve regurgitation by transthoracic echocardiography. The diagnostic accuracy of CT in detecting aortic valve regurgitation was as follows: sensitivity of 73% (33/45), specificity of 97% (35/36), positive predictive value (PPV) of 97% (33/34), and negative predictive value (NPV) of 74% (35/47). All 12 false-negative findings by CT were graded as mild regurgitation by transthoracic echocardiography and were caused by severe valve calcification (mean, 3,053.1 +/- 1,700 Agatston units; range, 937.7-5,632.5 Agatston units), bicuspid valves, or both. The sensitivity, specificity, PPV, and NPV of CT for the detection of moderate and severe aortic valve regurgitation were 95%, 100%, 100%, and 98%, respectively. Quantification of the ARA by CT (mean, 0.25 cm(2) +/- 0.34 cm(2) [SD]) was significantly correlated with the severity of aortic valve regurgitation by trans thoracic echocardiography (p < 0.001). CONCLUSION: Although 64-MDCT accurately detects moderate and severe aortic regurgitation in patients referred to coronary CT angiography, mild aortic regurgitation can be missed on 64-MDCT in the presence of severe valve calcification or bicuspid valves.

Device dislocation, probably due to paroxysmal coughing early after percutaneous closure of secundum type atrial septal defect.

In a 56-year-old woman with a secundum-type atrial septal defect, a closure device was successfully implanted with primarily adequate positioning of the occluder. Two weeks after discharge, the patient developed paroxysmal coughing that probably led to a device dislocation. Months later, a considerable left-to-right shunt was detected, and the device was found to be ingrown in a defective position and had to be removed surgically. In conclusion, the case demonstrates that recurrent coughing may interfere with closure devices and may lead to dangerous dislocation.

Totally endoscopic coronary artery bypass grafting on the arrested heart.

In the late 1990s, totally endoscopic coronary artery bypass grafting was successfully introduced into the heart surgery armamentarium using robotic techniques. Surgeons have applied the da Vinci telemanipulation system in order to develop completely endoscopic placement of internal mammary artery bypass grafts, mainly to the left anterior descending artery system. Multivessel procedures are currently under development. These operations can be carried out on the arrested heart using remote access perfusion and cardioplegic arrest via ascending aortic balloon occlusion. Another option is performing procedures on the beating heart using an endostablilizer and local coronary artery occlusion. In this review, the technique and specific aspects of the arrested heart version of totally endoscopic coronary artery bypass grafting are outlined.

Slightly elevated serum creatinine predicts renal failure requiring hemofiltration after cardiac surgery.

BACKGROUND: Acute renal failure (ARF) after cardiac surgery is a serious adverse event that is associated with high perioperative mortality and prolonged hospitalization. The aim of our study was to evaluate pre- and intraoperative risk factors for the development of ARF requiring hemofiltration after cardiac surgery. METHODS: From February 2002 through February 2003, 913 patients underwent cardiac surgery at our institution. Seventy-three patients developed ARF (8.1%), 16 patients were excluded from the study because of chronic end-stage renal insufficiency. Patient characteristics and operative variables were analyzed. A multivariate logistic regression analysis was performed to determine risk factors for ARF. RESULTS: Patients who developed ARF were older (P < .001; odds ratio [OR], 1.084; 95% confidence interval [CI], 1.0371.133) than patients who did not develop ARF. Furthermore, cardiopulmonary bypass duration (P = .007; OR, 1.013; 95% CI, 1.004-1.032) and emergent surgery (P = .011; OR, 6.667; CI, 1.538-28.571) were predictive for development of ARF. The strongest predictor for ARF was a preoperative creatinine level >or=2 mg/dL (P < .001; OR, 97.519; 95% CI, 22.363425.252). Most interestingly, even moderately elevated preoperative creatinine levels (1.3-1.99 mg/dL) independently predict ARF after cardiac surgery (P = .001; OR, 3.838; 95% CI, 1.793-8.217). CONCLUSION: Our data indicate that emergent surgery as well as advanced age and long duration of cardiopulmonary bypass independently predict ARF after cardiac surgery. Most importantly, even slightly impaired preoperative creatinine levels predict the development of ARF requiring hemofiltration after cardiac surgery.