Kay-Hyun Park

Prevention of Acute Kidney Injury by Erythropoietin in Patients Undergoing Coronary Artery Bypass Grafting: A Pilot Study

Background/Aims: Depending on the specific definition, acute kidney injury (AKI) occurs in 7–40% of patients undergoing cardiac surgery. Even small changes in serum creatinine (SCr) levels are associated with increased mortality after cardiac surgery. However, there are no current methods for preventing AKI after cardiac surgery. Erythropoietin (EPO) has been shown to elicit tissue-protective effects in various experimental models. In this pilot trial, we evaluated the effectiveness of EPO in the prevention of AKI after coronary artery bypass grafting (CABG). Methods: 71 patients scheduled for elective CABG randomly received either 300 U/kg of EPO or saline intravenously before surgery. AKI was defined as a 50% increase in SCr levels over baseline within the first 5 postoperative days. Estimated glomerular filtration rate (eGFR) was calculated from the Cockcroft-Gault equation. Results: Of 71 patients, 13 developed postoperative AKI: 3 of the 36 patients in the EPO group (8%) and 10 of the 35 patients in the placebo group (29%; p = 0.035). The increase in postoperative SCr concentration and the decline in postoperative eGFR were significantly lower in the EPO group than in the placebo group. Conclusions: In our small, pilot trial, prophylactic administration of EPO prevents AKI and improves postoperative renal function. These data are preliminary and require confirmation in a larger clinical trial.

Midterm Change of Descending Aortic False Lumen After Repair of Acute Type I Dissection

BACKGROUND Persistent false lumen in the descending aorta after repair of acute type I dissection adversely affects long-term prognosis. In this study, we investigated changes of the descending aortic false lumen during the midterm postoperative period. METHODS Postoperative computed tomographic (CT) images of 122 patients who underwent conventional ascending with or without arch replacement for acute type I dissection were reviewed. Patency and width of false lumen and maximal diameter of the aorta were compared between early and last follow-up images. Changes were analyzed separately in the thoracic and abdominal segments. RESULTS In early CT, thoracic false lumen was patent in 85 patients (69.7%), and abdominal false lumen was patent in 111 patients (91.0%). Among these, the false lumen remained patent after a mean interval of 33.6 months in 69 patients (81.1%) and 105 patients (94.6%), respectively. In 58 patients (47.5%), the descending aorta dilated by 1 cm or more. Dilatation occurred more frequently in the thoracic aorta and in patients with patent or wide false lumens, larger aortic diameter, Marfan syndrome, younger age, and male sex. Meanwhile, shrinkage of thoracic false lumen occurred in 36 patients (29.5%). Such shrinkage occurred in 23 of 24 patients (95.8%) who had thrombosed and narrow false lumens in the thoracic aorta. CONCLUSIONS Early postoperative characteristics of false lumen were helpful for predicting both dilation and regression. Our data show not only a high incidence of descending aortic dilatation after repair of acute type I dissection, but also shrinkage of thoracic false lumen in some patients. These findings can be used as control data for determining the benefit of more extensive or new surgical approaches.

Prevalence of Aortic Intimal Defect in Surgically Treated Acute Type A Intramural Hematoma

BACKGROUND Controversies exist regarding the pathogenesis and adequate management of intramural hematoma (IMH) of the aorta that has been commonly defined as a dissection without intimal tear. Recent studies reported that intimal defects are found in some patients diagnosed as IMH. We aimed to investigate the prevalence of such cases in surgically treated patients. METHODS Preoperative and postoperative computed tomographic (CT) scan images were retrospectively reviewed for 37 patients who underwent surgery for Stanford type A acute IMH. Operative findings were also reviewed from the medical records. RESULTS In 18 patients (48.6%), intimal defects were suggested in preoperative computed tomography (CT). During surgery, 27 patients (73.0%) had small intimal defects in the ascending aorta or arch, while 14 of them (51.9%) did not have preoperative CT findings suggestive of intimal defects. In 18 patients, the defects were located in the arch or distal ascending aorta, where they would not have been found if not inspected under total circulatory arrest. In all patients, the identified intimal defects were included in the aortic resection, or locally closed. Follow-up CT done at 4 months or longer after surgery showed that the IMH in the descending aorta disappeared or markedly improved in all patients. CONCLUSIONS On the basis of our results, we think that a large proportion of IMH may have a similar pathogenic mechanism as classic dissection and the conventional definition of IMH should be changed. For type A lesions treated with surgery, we recommend thorough inspection of the ascending aorta and the arch under hypothermic circulatory arrest.

Is tricuspid valve replacement a catastrophic operation

OBJECTIVE Tricuspid valve replacement (TVR) has a high postoperative mortality, despite recent advances in perioperative care. We report the results of our experience in TVR with an emphasis on early mortality and morbidity and long-term follow-up. METHODS Between October 1994 and August 2007, 80 consecutive TVRs were performed in 78 patients. The mean age was 48+/-14 (range: 20-70) years. The underlying disease of the patients was classified as rheumatic (n=54), congenital (n=12), endocarditis (n=10) or degenerative (n=4). Previous cardiac surgery had been performed in 40 patients (50%). Isolated TVR was performed in 24 patients (30%). RESULTS Hospital mortality occurred in one patient (1.4%). Postoperative morbidities included intra-aortic balloon pump (n=5), bleeding re-operation (n=4), delayed sternal closure (n=3), acute renal failure (n=3), subdural haematoma (n=3), extracorporeal membrane oxygenation (n=1), mediastinitis (n=1) and pacemaker insertion (n=4). In 42 patients, ventilator support was needed for more than 72 h. Based on multivariate analysis, age (p<0.001) and the cardiopulmonary time (p=0.004) were the identified risk factors. Follow-up was completed in all patients with a mean duration of 56+/-37 (range: 0-158) months. During the follow-up period, there were seven deaths (8.8%), including five cardiac deaths. The 5- and 8-year survival rates were 95+/-3% and 79+/-9% and event-free survival rates were 76+/-6% and 61+/-9%, respectively. Based on multivariate analysis, the only identified predictors of late deaths was a postoperative low cardiac output (p=0.024). CONCLUSIONS TVR can be performed and low operative mortality can be achieved thorough optimal perioperative management in the current era.

Subclinical Hypothyroidism Might Increase the Risk of Transient Atrial Fibrillation After Coronary Artery Bypass Grafting

BACKGROUND Some studies have proposed that subclinical hypothyroidism (SCH) has adverse effects on the cardiovascular system, but little is known about the effect on patients undergoing cardiovascular operations. We examined the influence of preoperative SCH on postoperative outcome in patients undergoing coronary artery bypass grafting (CABG). METHODS Among patients who underwent CABG between July 2005 and June 2007 at Seoul National University Bundang Hospital, 224 with normal thyroid function and 36 with SCH were enrolled. Preoperative risks and postoperative outcomes were evaluated prospectively without thyroid hormone replacement. RESULTS There were no significant differences in primary outcomes (major adverse cardiovascular events) and secondary outcomes such as wound problems, mediastinitis, leg infection, respiratory complications, delirium, or reoperation during the same hospitalization. However, patients with SCH had a higher incidence of postoperative atrial fibrillation than those with normal thyroid function after adjustment for age, gender, body mass index, and other independent variables such as emergency operation, the use of cardiopulmonary bypass, combined valvular operation, preoperative creatinine levels, left ventricular systolic dysfunction, and nonuse of beta-blockers (45.5% vs 29%; odds ratio, 2.552; 95% confidence interval, 1.117 to 5.830; p = 0.026). CONCLUSIONS SCH appears to influence the postoperative outcome for patients by increasing the development of postoperative atrial fibrillation. However, it is still unproven whether preoperative thyroxine replacement therapy for patients with SCH might prevent postoperative atrial fibrillation after CABG.

Coronary Artery Bypass Grafting Versus Drug-Eluting Stent Implantation for Left Main Coronary Artery Disease (from a Two-Center Registry)

Recent studies have suggested that percutaneous coronary intervention (PCI) in patients with unprotected left main coronary artery (LMCA) disease renders outcomes comparable to those from coronary artery bypass grafting (CABG). It is necessary to stratify individual patient risk and select the optimal revascularization strategy. We compared the clinical outcomes of patients with unprotected LMCA disease who had undergone PCI with drug-eluting stents or CABG. We identified 462 patients who were treated from January 2003 to December 2006 for unprotected LMCA or LMCA-equivalent disease: 257 had undergone CABG and 205 had undergone PCI with drug-eluting stents. Analyses using propensity scores were performed to minimize the selection bias in the present observational study. After a median follow-up of 33.5 months, no significant difference was found between the CABG and PCI groups in the risk of death (12.1% vs 14.1%, respectively; p = 0.428) or the risk of a composite of death, myocardial infarction, or cerebrovascular accident (17.5% vs 20.0%, respectively; p = 0.434). The rate of major adverse cardiac and cerebrovascular events was significantly lower in the CABG group than in the PCI group (21.8% vs 35.1%, respectively; p = 0.001); the difference was mainly driven by a decrease in the rate of repeat revascularizations (5.1% vs 22.4%; p <0.001). The analyses after propensity score adjustment and matching corroborated the crude group results. In conclusion, PCI with drug-eluting stents showed a safety profile comparable to that of CABG in patients with unprotected LMCA disease. However, the risk of repeat revascularization was significantly greater in the PCI group.

Results of Extracorporeal Membrane Oxygenation (ECMO) Support before Coronary Reperfusion in Cardiogenic Shock with Acute Myocardial Infarction

Background Despite aggressive treatment, the mortality rate of cardiogenic shock with acute myocardial infarction (AMI) is high. We performed extracorporeal membrane oxygenation (ECMO) prior to coronary reperfusion, and evaluated the early clinical results and risk factors. Materials and Methods From May 2006 to November 2009, we reviewed the medical records of 20 patients in cardiogenic shock with AMI (mean age 67.7±11.7 yrs, M : F 14 : 6). After initially performing ECMO using the CAPIOX emergency bypass system (EBS®Terumo, Tokyo, Japan), patients underwent coronary reperfusion (coronary artery bypass grafting, 13; percutaneous coronary intervention, 7). Results All patients were in a cardiogenic shock state, cardiopulmonary resuscitations (CPR) were performed for fourteen patients (mean CPR time 20.8±26.0 min). The mean time from vascular access to the initiation of ECMO was 17.2±9.4 min and mean support time was 3.8±4.0 days. Fourteen patients were able to be weaned from ECMO and ten patients were discharged (mean admission duration 50.1±31.6 days). Patients survived on average 476.6±374.6 days of follow-up. Longer CPR and support time, increased cardiac enzyme, lower ejection fraction, lower albumin, and major complications were the risk factors of mortality (p<0.05). Conclusion The early application of ECMO prior to coronary reperfusion and control of risk factors allowed for good clinical results in cardiogenic shock with AMI.

Suitability of Endovascular Repair with Current Stent Grafts for Abdominal Aortic Aneurysm in Korean Patients

Suitability rate of endovascular aneurysm repair (EVAR) and the anatomic features causing unsuitability have not been well determined in Asian patients who have abdominal aortic aneurysm (AAA). In a single Korean center, a total of 191 patients with abdominal aortic aneurysm (maximal diameter ≥ 4 cm) were identified. Aortoiliac morphologic characteristics in contrast-enhanced computed tomography images were retrospectively reviewed to determine suitability for EVAR with four FDA-approved stent-grafts. AAA was considered ideally suitable for EVAR in 46.6% of patients. The most frequent causes for unsuitability were common iliac artery (CIA) aneurysm (61.8%) and excessive neck angulation (52.9%). Problems such as small and/or short neck and small access were found in minor incidences. If CIA aneurysm is dealt by overstenting with sacrifice of internal iliac artery, suitability rate can increase to 65%. Larger aneurysms were more frequently unsuitable for EVAR and had more chance of having multiple unfavorable features. In conclusion, the overall feasibility rate for EVAR in Korean patients was not different from that in Western patients. However, considering the difference in the major causes of unsuitability, more attention has to be paid to neck angulation and CIA aneurysm to provide EVAR for more Korean patients especially who have large aneurysm.

Clinical impact of computerised tomographic angiography performed for preoperative evaluation before coronary artery bypass grafting

OBJECTIVE In our institution, computerised tomographic (CT) angiography has been performed as a near-routine test before coronary artery bypass grafting (CABG) to evaluate the aorta and its branches. We aimed to determine its impact on operative procedure and perioperative management. METHODS From January 2006 through December 2008, neck-to-leg systemic arteries were evaluated by 64-slice multidetector CT scan in 284 patients before CABG. For them, medical records and cardiac surgery database were retrospectively reviewed to investigate the incidence of pathologic lesions of the aorta and its major branches, other incidental lesions and procedure- or management-related decision affected by CT angiography. RESULTS In 36 patients (12.7%), cannulation and clamping of the ascending aorta were thought too dangerous because of severe atherosclerotic change. The use of cardiopulmonary bypass was inevitable in 10 of them, and postoperative mortality rate was significantly higher (3/10, 30%) than in the remaining patients (2/274, 0.7%). Conduit selection or grafting strategy was changed due to severe left subclavian artery stenosis or leg vein varicosity in 18 patients (6.3%). For the following problems, surgical interventions were performed in 34 patients (12.0%) concomitantly or during the same admission with CABG; > or = 90% stenosis in carotid (5.6%), iliofemoral (11.6%) or renal (4.6%) arteries, aortic aneurysm (14.4%, six of them met surgical indication) and incidental malignant neoplasm (2.8%). Counting all of the above, preoperative CT angiography affected risk assessment, CABG procedure itself, perioperative management or follow-up plan in 142 patients (50%). CONCLUSIONS Because preoperative CT angiography considerably affected management in one half of patients, we recommend its use as a routine test before CABG, unless contraindicated.

Candidates and major determinants for endovascular repair of abdominal aortic aneurysms in Korean patients

The purpose of this study was to determine what proportion of patients with an abdominal aortic aneurysm (AAA) would be eligible for endovascular aneurysm repair (EVAR) and to examine the major determinants for suitability of EVAR with the currently available indications. We retrospectively reviewed 3-D reconstructed computed tomography angiography of 88 patients with an atherosclerotic AAA who underwent open repair or EVAR between October 2003 and October 2010 at the Cardiovascular Center, Seoul National University Bundang Hospital. Of the 88 patients, 71 (80.7%) were treated with open repair and 17 (19.3%) were treated with EVAR. The rate of minor complications, postprocedural intensive care unit stay, and total hospital stay were significantly lower in the EVAR group. When the suitability of EVAR was reevaluated using morphologic criteria, a total of 33 (37.5%) patients were considered eligible for EVAR. Multivariate analysis revealed that proximal neck length, proximal neck angle, and aneurismal sac size were independent determinants for suitability of EVAR. Taking into account the increased clinical experience and the availability of new devices, EVAR would be applicable in about 40% of atherosclerotic AAA cases in this series of Korean patients. Accurate identification of candidates for EVAR by detailed preoperative evaluation, especially for morphologic characteristics, is essential.