髙味 良行

Background. Few data are available on the outcomes of aortic valve replacement (AVR) in dialysis patients. Valve selection has been controversial, and systemic calcification in these patients has been an important concern. This study reports our experiences and evaluates whether dialysis patients can be treated in a way that is similar to nondialysis patients. Methods. A retrospective review was performed on 73 AVRs (43 men, 29 women), including one redo operation, for dialysis patients between 1995 and 2007. Mean age was 65.0 +/- 8.3 years. The bioprosthesis was basically selected for elderly patients as for nondialysis patients. Results. For a severely calcified ascending aorta, the femoral or subclavian artery was selected for arterial cannulation in 9 patients (12.3%), and aortic cross-clamping under temporary circulatory arrest with moderate hypothermia was applied in 17 (23.3%). Implanted were 51 mechanical and 22 bioprosthetic valves. Four elderly patients in poor general condition received high-performance mechanical valves instead of bioprosthesis to avoid aortic root enlargement. There was no stroke during the perioperative period. Hospital mortality was 6.8%. The overall actuarial survival rate was 74.6% +/- 5.6%, 55.7% +/- 7.6%, and 39.9% +/- 9.7% at 3, 5, and 10 years, respectively. Conclusions. The results for the dialysis patients after AVR were satisfactory. Dialysis patients can be treated in AVR just like nondialysis patients. Valve selection and surgical strategy on a case-by-case basis are important to improve the clinical outcomes in dialysis patients. (Ann Thorac Surg 2010; 89: 65-71) (C) 2010 by The Society of Thoracic Surgeons

Background. The mortality and morbidity rates are high after cardiac surgery in hemodialysis (HD)-dependent patients. To improve their outcomes, optimal perioperative managements should be discussed. Methods. A retrospective analysis of 245 HD patients who underwent cardiac surgery between 1994 and 2007 was conducted. The basic management strategies were (1) low-potassium HD for 2 days before surgery, (2) only hemofiltration during cardiopulmonary bypass, and (3) start of regular intermittent HD on the first postoperative day. Continuous venovenous hemodiafiltration was applied only for patients with hemodynamic instability. Results. The causes of renal failure included diabetic (n = 89, 36%), glomerulonephritis (n = 49, 20%), and unknown (n = 75, 31%). The history of HD was 9.7 +/- 7.6 years. The operative procedures included coronary (n = 135), valve (n = 103), and others. The amount of intraoperative ultrafiltration was 6,123 +/- 324 mL during cardiopulmonary bypass for 197 +/- 67 minutes. Two hundred eight patients (85%) were managed with only intermittent HD, whereas 36 patients (15%) needed continuous venovenous hemodiafiltration. The use of continuous venovenous hemodiafiltration significantly declined during the year (26% before 2003 and 3% after 2003; p < 0.001). The amount of fluid removal on the first postoperative day was 1,297 +/- 81 mL. The hospital mortality was 9.7% with the causes including infection (n = 11), cardiac events (n = 6), gastrointestinal events (n = 5), and stroke (n = 2). A multivariate logistic regression analysis revealed that selection of intermittent HD or continuous venovenous hemodiafiltration was not related to the hospital mortality. Conclusions. Simplified management only with intermittent HD can be safely performed in most HD-dependent patients undergoing cardiac surgery. (Ann Thorac Surg 2009;88:1515-9) (C) 2009 by The Society of Thoracic Surgeons

Objective: We investigated flow characteristics of right gastroepiploic arterial grafts, widely used to extend in situ arterial conduits in coronary artery bypass grafting. Methods: Intraoperative transit-time measurements and postoperative angiographic findings were obtained for 111 patients undergoing coronary artery bypass grafting with gastroepiploic artery and bilateral internal thoracic arteries: mean, maximum, and minimum flows; pulsatility index; insufficiency rate; and differentiated index of early diastolic flow. Results: Favored target for gastroepiploic artery was posterior descending artery (106 patients, 95%). Patency rates were 91.0% for gastroepiploic artery, 98.2% for left internal thoracic artery, and 97.5% for right internal thoracic artery. There were four flow profiles of gastroepiploic arteries: A (systolic protruded), B (trapezoidal), C (sine waved), and D (diastolic-dominant biphasic). Functional gastroepiploic arteries showed A in 16 cases, B in 6, C in 31, and D in 48, with prevalence according to severity of stenosis in target coronary artery. Two occluded gastroepiploic arteries showed type A, and reverse or competitive flows were types A in 1, B in 1, C in 4, and D in 2. Relative to functional internal thoracic arteries, functional gastroepiploic arteries showed significantly lower minimum flow, higher insufficiency rate, and lower differentiated index of early diastolic flow. Conclusion: Intraoperative transit-time flow profiles of patent in situ gastroepiploic arterial grafts were classified into four types, closely associated with disease severity of target coronary artery. Patent in situ gastroepiploic arterial grafts show more regurgitant flow and lower differentiated index of early diastolic flow than in situ internal thoracic arterial grafts.

Preoperative autologous blood donation (PAD) is important for reducing exposure to allogenic blood in cardiac surgery. Unfortunately, even after PAD, allogenic blood transfusion is not always avoided. We investigated the predictors of blood component usage during elective cardiac surgery in patients prepared with PAD. Clinical data were collected for 143 consecutive patients (103 men and 40 women; mean age, 62 +/- 9 years) who underwent elective cardiac surgery after PAD (959 +/- 240 ml), often using iron supplement and recombinant human erythropoietin. Allogenic blood transfusion was avoided during and after surgery in 107 patients (75%), whereas 36 patients required an allogenic transfusion (4.1 +/- 3.8 U of packed red cells, 3.4 +/- 4.1 U of fresh frozen plasma, and 5.8 +/- 11.0 U of platelet concentrate). The independent factors for perioperative allogenic blood transfusion in these patients included the pre-donation hemoglobin value, the preoperative platelet count, and the lowest hemoglobin value during cardiopulmonary bypass. Even with PAD for elective cardiac surgery, patients whose pre-donation hemoglobin value and preoperative platelet count are low may require allogenic blood transfusion.

Objective: Cardiac surgery in patients with severely atherosclerotic or porcelain ascending aorta is technically challenging, with markedly increased risk of atheroembolism. We describe a technique of meticulous crossclamping of a difficult aorta during short-term moderate hypothermic circulatory arrest. Methods: From 1997 to 2007, we found 40 patients (mean age, 70 +/- 8 years), including 14 patients undergoing hemodialysis, whose preoperative computed tomographic and intraoperative epiaortic ultrasonographic scans revealed eggshell calcification (n = 15) or protruding atheromas (n = 25) of the ascending aorta. They underwent cardiac surgery (aortic, 31 patients; mitral, 3 patients; both, 5 patients; and coronary alone, 1 patient) by means of meticulous crossclamping during hypothermic circulatory arrest for 3.4 +/- 1.5 minutes at a rectal temperature of 29.0 degrees C +/- 2.3 degrees C. During hypothermic circulatory arrest, we performed only internal inspection to identify the safe location of crossclamping in 21 patients, whereas we required debridement of calcification or atheroma by using the Cavitron Ultrasonic Surgical Aspirator (Tyco Healthcare, Mansfield, Mass) for safe crossclamping in 19 patients. Results: By using this technique, no patients died during the hospital stay. Stroke occurred in 1 (2.5%) patient, and transient agitation occurred in 1 patient. Re-exploration for bleeding was required in 1 patient, and wound infection occurred in 2 patients. During follow-up, with a median time of 5.2 years, the overall survival rates were 100%, 90%, and 76% at 1, 3, and 5 years, respectively. Three patients required reoperations during the follow-up period because of pseudoaneurysm in 2 patients and prosthetic valve infection in 1 patient. Conclusion: Short-term moderate hypothermic circulatory arrest is quite useful for safe aortic crossclamping after internal inspection or debridement in high-risk patients with a severely atherosclerotic aorta.

Background. We investigated hemodynamic effects of intra-aortic balloon pumping (IABP) in in-situ and aortacoronary (A-C) grafts during coronary artery bypass grafting (CABG). Methods. One hundred seventy-two grafts, including 84 in-situ left internal thoracic arteries (LITAs), were examined intraoperatively with a transit-time flowmeter in 84 patients who had prophylactic IABP. The following measurements were obtained for each graft during off-IABP and on-IABP: mean flow, maximal flow, pulsatility index, and diastolic filling index. Coronary angiograms were performed 14 +/- 5 days after coronary artery bypass graft surgery to verify the patency of the grafts. Results. All measurements of 163 patent and measurable grafts were significantly increased with IABP: mean flow 46 +/- 27 to 51 +/- 29 mL/min; maximal flow 87 +/- 52 to 121 +/- 69 mL/min; pulsatility index 2.2 +/- 1.4 to 3.1 +/- 1.4; and diastolic filling index 64% +/- 8% to 71% +/- 9% (p < 0.001). Among them, the degrees of increase of mean flow and diastolic filling index were significantly different between the in-situ LITAs and A-C grafts (mean flow 18% +/- 20% versus 10% +/- 15%, p = 0.04; diastolic filling index 10% +/- 8% versus 14% +/- 9%, p = 0.04). Conclusions. IABP assist significantly increases graft flow and also diastolic components of flow. The degree of increase is greater in the in-situ LITA supplying the left anterior descending artery than in A-C grafts anastomosed to other coronary arteries. IABP increases the diastolic component more in A-C grafts than in in-situ LITAs, probably because of different flow characteristics of the two grafts.

Objective. The conclusions remain controversial about whether the sternal blood flow is preserved or diminished after internal thoracic artery (ITA) harvesting for coronary artery bypass grafting (CABG), especially in diabetic patients. We investigated the blood supply of the chest wall noninvasively using near-infrared spectroscopy (NIRS) immediately after CABG. Methods. The study group comprised 30 patients who underwent CABG using a skeletonized left ITA through median sternotomy. As a control group, three nondiabetic patients undergoing valve surgery through median sternotomy were also included. On arrival of the patient in the intensive care unit immediately after surgery, two reflectance sensors were placed on the bilateral parasternal regions at the fourth intercostal space to record regional oxygen saturation (rSO2) and hemoglobin index (HbI) continuously approximately for 17 h. Results. The differences in right and left values (R-L rSO2 and R-L HbI) were significantly greater in the diabetic patients than in the nondiabetic patients (3.74% ± 2.47% vs. 1.98% ± 1.67 %, p = 0.036 and 0.28 ± 0.19 vs. 0.13 ± 0.13, p = 0.020). The R-L HbI was significantly greater in the on-pump patients than in the off-pump patients, although there was no significant difference in R-L rSO2. Both R-L rSO2 and R-L HbI were similar among the control, nondiabetic, and off-pump patients. Conclusion. The technique of NIRS enables noninvasive, continuous monitoring of chest wall perfusion immediately after ITA harvesting. Our study using NIRS showed a decrease in blood flow and oxygen metabolism of the hemisternum after LITA harvest in diabetic CABG patients. © 2008 The Japanese Association for Thoracic Surgery.

We present a case of disruption of the porcine aortic wall of the 27-mm Freestyle stentless bioprosthesis 5 years after the subcoronary implantation to exclude the sinus of Valsalva aneurysm of the noncoronary cusp. At the urgent reoperation, the inflow suture line was found to be intact, and therefore a new stented valve was sutured with the inflow Dacron cuff after removal of ruptured valve. The subcoronary implantation technique creates a cavity between the prosthetic and native aortic walls filled with hematoma. The outflow suture line dehiscence caused blood flow into the cavity, porcine aortic wall rupture, and leaflet destruction.

体外循環における経皮的炭酸ガス分圧モニターSENTEC社デジタルモニターシステムを臨床使用した。体外循環を行った2症例の成人患者を対象とした。SENTECのプローブを右耳朶に装着した。術中、無作為に経皮的炭酸ガス分圧(tcPCO2)並びに左橈骨動脈、あるいは人工心肺回路からのPaCO2を同時測定し比較検討した。人工換気および体外循環中の相関係数はR=0.62(P<0.05)、回帰直線はY=1.02X-1.37で正の相関を認めた。しかし末梢組織での炭酸ガス換気応答を見るtcPCO2モニターは体外循環に伴う不均衡な末梢循環のため、PaCO2とtcPCO2の測定値にばらつきが見られた。そのため体外循環におけるtcPCO2モニターは不均衡な末梢循環のため、炭酸ガス換気応答の指標としては信頼性が低いことが示唆された。

Background. Coronary artery bypass grafting (CABG) is best indicated for chronic total occlusion of the left anterior descending artery (LAD) with collaterals. We investigated angiographic changes in the collateral circulation after CABG. Methods. Preoperative and postoperative angiograms were reviewed in 42 patients who underwent grafting onto occluded LADs. We described the type, location, and size of collaterals, the Rentrop grading, and collateral frame count (CFC). Regional wall motion of the LAD area was also evaluated with the centerline method. Postoperatively, we measured the lengths of LAD proximal (Lp) and distal (Ld) to the graft anastomotic site. Results. Preoperative collaterals comprised 78 pathways (septal 42%, branch-branch 20%, atrial 19%, bridging 18%). After CABG, residual collaterals were identified, mainly through the septal pathways, in 6 patients (14%), most of whom were diabetic. The residual collaterals were a part of those which had been opacified in earlier phases of the preoperative angiograms (CFC: 17 +/- 3 vs 25 +/- 15, p = 0.01). Also, the Ld was shorter in these patients so that Lp/Ld was greater than in patients without residual collaterals (0.80 +/- 0.24 vs 0.53 +/- 0.28, p = 0.04). We found no association of residual collaterals with the improvement of LAD regional wall motion after CABG. Conclusions. Even after successful CABG, some collaterals with earlier filling of the LAD remain, mainly through the septum. Although the clinical significance remains to be clarified, complex and diffuse atherosclerosis associated with more distal graft anastomoses may contribute to maintaining collaterals after CABG to the occluded LAD, especially in diabetic patients.

Primary cardiac myxosarcoma is a rare disease; it is exceedingly rare for symptoms of systemic metastasis to precede diagnosis of the primary cardiac tumor. We describe the case of a previously healthy 60-year-old man with left atrial myxosarcoma, who had first presented with jejunal intussusception due to intestinal polyposis. Three months after resection of the jejunum, the patient experienced cerebral infarction and pulmonary edema. Further physical evaluation, which included echocardiography for the 1st time, revealed a mass in the left atrium that protruded through the mitral valve into the left ventricle. At emergency cardiac surgery, we found that the tumor involved multiple sites of the left atrium, the pulmonary veins, and the mitral anterior leaflet. Two months after surgery, the patient died of massive cerebral hemorrhage. Necropsy disclosed multiple recurrences of the cardiac myxosarcoma and widespread metastatic lesions. The intestinal polyps that had been resected originally were diagnosed, on retrospective histopathologic examination, as metastases of the myxosarcoma. In this unusual case, the metastatic lesions were the 1st clinical manifestations of a malignant cardiac tumor.

Objective. Liver cirrhosis is recognized as one of the risk factors for severe complications after cardiac surgery. However, there are no established methods for risk stratification of the patients with liver cirrhosis (LC) regarding cardiac surgery. We present our experience of preoperative evaluation of liver function using asialoscintigraphy. Methods. Between April 1999 and December 2005, we evaluated preoperative liver function using asialoscintigraphy with technetium-99m galactosyl human serum albumin in four cirrhotic patients undergoing coronary artery bypass grafting (n = 2) and valve replacement (n = 2), whose etiologies of LC were alcoholabuse (n = 1) and hepatitis C virus infection (n = 3). They also underwent other tests for preoperative evaluation of liver function, including the indocyanine green (ICG) test. Results. Asialoscintigraphy revealed that the receptor index and the index of blood clearance in each patient were 0.81/0.73, 0.95/0.5, 0.82/0.62, and 0.97/0.57, respectively. These values closely correlated with the results of the ICG test. All patients were discharged alive from hospital after surgery. However, although one patient who underwent off-pump bypass had an uneventful course, three patients had major complications: pleural effusion (n = 1) and wound infection (n = 2). Conclusion. Asialoscintigraphy is a practical, reliable method that can replace the ICG test for estimating hepatic function for risk stratification of cirrhotic patients undergoing cardiac surgery, whose mortality and morbidity are still high. © The Japanese Association for Thoracic Surgery 2006.

We have been using magnetic resonance angiography (MRA) preoperatively to identify patients at increased risk of stroke in coronary artery bypass grafting (CABG). Based upon the intracranial MRA findings, either the off-pump or the on-pump procedure was selected. We report the results of our MRA-based strategy of CABG in 140 consecutive patients. Intracranial arterial lesions were found in 90 patients (64%). The most affected arteries were internal carotid (48%), followed by vertebral (18%) and middle cerebral (16%). Using the MRA score describing the severity of intracranial atherosclerosis, 35 patients with a score of ≥5 underwent off-pump, while 105 patients with a score of &lt 5 underwent on-pump CABG. In the off-pump group, the patient age was older, the incidence of abnormal preoperative brain CT was higher, and the MRA score was higher (6.0 ± 1.1 vs. 1.2 ± 1.3 points) than in the on-pump groups. Even though the risk was higher in the off-pump group, the clinical outcomes were not significantly different, including the hospital mortality and the incidence of stroke and additional coronary intervention. In conclusion, the brain MRA-based selection of off-pump CABG can contribute to prevention of stroke in neurologically high-risk patients.

Centrifugal pumps have been increasingly used in clinical settings. Like roller pumps, centrifugal pumps can cause debris release due to mechanical stress. The objectives of this study were to evaluate in vitro the particle release from a centrifugal pump, Gyro Pump (Japan Medical Materials Co., Osaka, Japan), which is a pivot-bearing supported pump clinically used in Japan, and to identify the released particles. In the clean room Class 10 000, the pump was operated for 24 h at 4000 rpm and 6 L/min in a mock loop filled with lactated Ringer's solution. After 24 h, the sample fluid and a blank were filtered with a 0.45-mu m membrane filter for microscopic counting, followed by observation with a scanning electron microscope and element analysis with an X-ray spectrometer. Microscopic countings were 128 +/- 42 in the test samples (n = 10) of the Gyro Pump and 98 +/- 42 in the blank samples (n = 10) (P = 0.12). The oxygen/carbon atomic ratio of the particles in the test samples was 0.32 +/- 0.06, which was similar to the ratio of the particles in the blank sample (0.34 +/- 0.06). The profiles of elements with an X-ray spectrometer showed that the released particles from the Gyro Pump were not derived from the pump materials. In conclusion, an in vitro test system has been established for estimation of particle release from a centrifugal pump. Based upon the results with the system, the Gyro Pump with a pivot-bearing system has little risk to release debris particles even in a severe condition.

簡便で信頼度・再現性が高いトランジットタイム法によるCABG術中グラフト血流分析において, 心電図信号を同期入力することにより血流量の収縮期成分(Qs)と拡張期成分(Qd)を同定し, 拡張期フィリング指数(DFI=100⎰Qd/[⎰|Qs|+⎰|Qd|])が得られる.術中にMedi-Stim社製トランジットタイム血流量計で平均血流量(Qm)(ml/min)・拍動指数(PI)・機能不全率(INSUF)(%)・DFI (%)・F0/H1(血流曲線を高速フーリエ変換した基本周波数(F0)とその2倍周波数(H1)のパワー比)を求め, 術後グラフト造影所見との関連を追究した.術後造影できたグラフト125本について, 開存グラフト(120本)と非開存グラフト(5本)の間で, Qm・PI・INSUF・DFI・F0/H1すべての指標において有意差を認めた.DFI>50%は, 他の指標のQm>15ml/min・PI<5・INSUF<15%・F0/H1>1.0とともにグラフト開存と術中に判断する有用な指標と考えられた.

興味ある限局型胸腹部大動脈瘤の1例を呈示する.症例は60歳, 女性.高血圧・高脂血症で通院中, 嘔気を認め当院を受診し, 両側水腎症・後腹膜繊維症・炎症性腹部大動脈瘤・胸腹部大動脈瘤の診断で入院となった.両側尿管狭窄に対して両側尿管ステント留置を施行され, 腎機能の改善後ひき続いて胸腹部大動脈瘤の手術を施行した.右大腿動静脈からの部分体外循環下に胸腔内のみで大動脈を遮断, 末梢吻合を先行し瘤切除・人工血管置換を施行した.腹部大動脈周囲の炎症・繊維化は胸部まで及んでいなかった.後腹膜繊維症・炎症性大動脈瘤・限局型胸腹部大動脈瘤の合併を, 発生機序・病態から文献的考察を加えて報告する.

Significant venous hypercarbia has been reported in septic shock and circulatory failure. Cardiopulmonary bypass also impairs systemic and pulmonary blood perfusion. The objective of this study was to determine the clinical significance of the increased venous-arterial CO2 tension gradient resulting from venous hypercarbia after cardiopulmonary bypass. On arrival in the intensive care unit, venous and arterial CO2 tensions were measured in the radial and pulmonary arteries in 140 consecutive patients who had undergone coronary (n = 79), valve (n = 34), aortic (n = 20), and other (n = 7) surgery under cardiopulmonary bypass. The mean venous-arterial CO2 tension gradient was 5.0 ± 3.3 mm Hg (range, 7.7 to 15.7 mm Hg). By linear regression analysis, the factors that significantly correlated with venous-arterial CO2 tension gradient were bypass duration, aortic crossclamp time, initial arterial lactate level, transpulmonary arteriovenous lactate difference, arterial bicarbonate level, base excess, cardiac index, mixed venous O2 saturation, CO2 delivery, O2 consumption, and the peak value of creatine kinase. The venous-arterial CO2 tension gradient may reflect impaired perfusion and anaerobic metabolism induced by cardiopulmonary bypass and could be a simple and useful indicator for patient management after surgery under cardiopulmonary bypass.

Background Although it has been reported that coronary artery bypass grafting (CABG) for multivessel disease markedly improves several parameters of signal-averaged electrocardiography (SAECG), its beneficial effect on SAECG is variable. The hypothesis of the present study was that the presence of diabetes mellitus (DM) affects the improvement in SAECG after CABG. Methods and Results Pre- and post-operative SAECGs were recorded in 100 consecutive patients who underwent complete surgical revascularization. Changes in the following parameters were compared between the diabetic (n=43) and non-diabetic (n=57) patients: filtered QRS duration (dQRS), root mean square voltage in the terminal 40 s of the QRS complex (RMS40), and duration of the terminal low-amplitude signal lower than 40muV (LAS40). Although baseline characteristics and the occurrence of late potentials were similar in both groups, quantitative improvements in the SAECG parameters after CABG were significantly greater in non-diabetic than in diabetic patients (dQRS: 109+/-22ms vs 102+/-19 ms in diabetics and 106+/-21 ms vs 88+/-11 ms in non-diabetics; p=0.028, RMS40: 55+/-46 muV vs 65+/-38 muV in diabetics and 50+/-37 muV vs 76+/-37 muV in non-diabetics; p=0.037, LAS40: 31+/-20 ms vs 26+/-17 ms in diabetics and 32+/-12 ms vs 17+/-8 ms in non-diabetics; p=0.007, respectively). Conclusions The presence of DM limits the CABG-induced improvement in SAECG. In diabetic patients, therefore, perioperative changes of the SAECG must be interpreted with caution.

To support injured lungs, we have been applying bilevel positive airway pressure for adult patients undergoing surgery with cardiopulmonary bypass. Among 120 consecutive patients, 31 patients whose PaO2/FiO 2 decreased to less than 180 after extubation assigned to the intermittent 15min bilevel positive airway pressure (7.3±3.6 times per patient). Bilevel positive airway pressure improved oxygenation (PaO 2/FiO2: 128±43 vs. 198±62, P=0.004) and allowed the patients with poor oxygenation after extubation to maintain PaO 2/FiO2 levels similar to those of the patients without bilevel positive airway pressure. In conclusion, the bilevel positive airway pressure therapy after extubation was effective to improve lung oxygenation non-invasively in adult patients undergoing more invasive surgery with prolonged cardiopulmonary bypass. © 2003 Elsevier Science B.V. All rights reserved.

Abnormal signal-averaged electrocardiography (SAECG) reflects slow and heterogeneous myocardial conduction, predicting ventricular arrhythmia and sudden cardiac death in patients with ischemic heart disease. The purpose of this study was to investigate the quantitative effect of coronary artery bypass grafting (CABG) on SAECG, which is still controversial, and to identify the factors that are related to it. Pre- and postoperative SAECGs were recorded in 100 patients who underwent CABG. Compared parameters included filtered QRS duration (dQRS), root mean square voltage in the terminal 40 ms of the QRS complex (RMS40), and duration of the terminal low-amplitude signal less than 40muV (LAS40). All 3 parameters in SAECG improved significantly after CABG (dQRS: 105 +/- 21 ms-->99 +/- 18 ms, RMS40: 55 +/- 45 muV-->65 +/- 41 muV, LAS40: 29 +/- 19 ms-->25 +/- 12 ms). The improvements in SAECG were greater in patients who underwent complete revascularization and in those without prior myocardial infarction. In conclusion, CABG improved SAECG quantitatively, even in patients with normal SAECG. However, this improving effect was variable and closely related to the presence of prior myocardial infarction and the completeness of revascularization.

We describe our experience of mitral valve surgery in a 74-year-old man with rheumatoid arthritis (RA). RA had been diagnosed 12 years previously and his symptoms were being controlled by drugs including methotrexate (MTX), which is potentially immuno- and myelo-suppressive. He was admitted for dyspnea, and surgery was indicated for severe mitral insufficiency due to posterior leaflet prolapse. According to the recommendations of orthopedic surgeons, the administration of the MTX was discontinued at two weeks prior to the operation, in which the prolapsed leaflet was excised, repaired, and annuloplasty were performed with a 30 mm prosthetics ring. The patient recovered uneventfully and MTX was resumed one week after surgery. Since MTX has been recently approval for treatment of RA in Japan, Japanese surgeons should pay attention to the appropriate perioperative use of this drug.

We describe our experience in treating a 69-year-old man with spinal progressive muscular atrophy (SPMA), who underwent a mitral valve replacement. He was admitted for dyspnea, and surgery was indicated for severe mitral insufficiency associated with inferior myocardial infarction. He had been aware of muscle weakness and received a diagnosis of SPMA 18 years previously. Worsening muscle atrophy had led to the need for him to use a wheelchair in his daily life. A preoperative examination revealed markedly reduced pulmonary function (% volume capacity = 44.8%). Because of an acute exacerbation of heart failure, the patient underwent an urgent mitral valve replacement with a 27-mm pericardial bioprosthesis. Although it took 42 h to wean him from the mechanical ventilation and he suffered from pulmonary atelectasis after extubation, he was discharged from our hospital in a wheelchair 16 days after surgery. Respiratory management with bilevel positive airway pressure was thus found to be quite useful for patients with neuromuscular disease.

A 54-year-old man, who had undergone atria] septal defect (ASD) closure 30 years previously, was admitted for exertional dyspnea and chest oppression. He presented with right pleural effusion and hepatomegaly. Hemodynamic characteristics were consistent with constrictive pericarditis caused by multiple cystic lesions anterior to the main pulmonary artery and right ventricle, and severe calcification over the posterior and diaphragmatic sides of the heart. Magnetic resonance imaging was useful for differential diagnosis of the cystic mass and at surgery, it was revealed that the cystic lesions were old hematoma without cells. Pericardiectomy and removal of the calcification were performed safely using an ultrasonic scalpel, without cardiopulmonary bypass, resulting in hemodynamic improvement and relief of his symptoms.

Background. We examined the hypothesis that complete skeletonization of an internal thoracic artery (ITA) results in increased diameter of the graft for anastomosis and therefore improves graft flow in coronary artery bypass grafting. Methods. We studied 65 consecutive patients who underwent coronary artery bypass grafting, in which the left ITA was anastomosed to the left anterior descending artery. The first 20 consecutive ITA were harvested as a pedicle (group P) and later 45 consecutive ITAs were harvested as an ultrasonically skeletonized graft (group S). Intraoperative ITA graft mean flows were obtained with a transit-time flowmeter. Three diameters of the ITA graft were measured quantitatively in postoperative angiograms performed 14 +/- 5 days after the coronary artery bypass grafting; D1, at the origin from the subclavian artery; D2, at the level of the second intercostal space; and D3, just proximal to the anastomosis. Results. Intraoperative mean flow was significantly a greater in group S than in group P (S: 42.6 +/- 29.1 mL/min versus P: 26.4 +/- 16.1 mL/min, p = 0.03). Although the diameters D1 and D2 were not significantly different between groups, D3 was significantly larger in group S than in group p (S: 1.77 +/- 0.28 mm versus P: 1.57 +/- 0.17 mm, p = 0.02). Conclusions. Compared with pedicle harvesting, complete skeletonization of ITA may make it possible to anastomose an ITA with a larger diameter in coronary artery bypass grafting, which leads to increased graft flow by decreasing vascular resistance.

We have been using the Gyro centrifugal pump C1E3 for cardiopulmonary bypass in anticipation of high efficiency, low hemolysis, and antithrombogenicity of this pump. However, the clinical evaluation of this pump remains to be clarified, because it has been a short time since the pump appeared in clinical situations. The aim of the present study is to inspect and analyze the Gyro pumps morphologically after clinical use. We examined 80 consecutive pumps after cardiopulmonary bypass for 186 ± 67 min with a mean flow rate of 2.52 ± 0.221/min/m2 at a mean rotational speed of 2485 ± 81.1 rpm. Although no abnormal findings were present in 79 pumps, one pump was found to contain effusion at the connection between the impeller body and the shaft. The extudate was supposed to be blood, based upon the results of X-ray spectrometer analysis. The cause was determined to be the upward deviation of the shaft off the impeller body. Scanning electron microscopy showed scratches on a part of the bottom housing and a smooth surface of both the male and female pivots of the pump. Surface profile measurement revealed that the deformity of the female pivots was 0.14 mm (top) and 0.05 mm (bottom). These observations suggest that the floating force and vibration by the rotating impeller acted on the joint zone between the alumina ceramic shaft and the polycarbonate impeller body, resulting in dissection of the adhesive agent from the polycarbonate. Although this abnormality may be rare, the structural design still may need to be improved.

Purpose. This study was conducted to determine the clinical significance of the initial lactate level and its transpulmonary difference after open-heart surgery in adult patients. Methods. The initial postoperative lactate levels were obtained from both radial and pulmonary arteries (La, Lv) in 65 consecutive patients undergoing coronary (n = 46), valve (n = 8), and aortic (n = 11) surgery. We analyzed the relationships between the perioperative factors and La and transpulmonary arteriovenous lactate difference (%La-v = 100(La - Lv)/Lv). Results. La and % La-v were not correlated with the preoperative factors of age, pulmonary function, or emergency surgery. La significantly correlated with the cardiopulmonary bypass time, initial arterial pH, initial PaO2/FiO(2), SVO2, O-2 consumption, 02 extraction rate, and the peak value of creatine phosphokinase. The %La-v significantly correlated with the aortic cross-clamp time, the lowest rectal temperature, the duration of intubation, and PaO2/FiO(2) after extubation. Conclusion. La may be an indicator of the invasiveness of the surgery, while %La-v may be a predictor of postoperative pulmonary function. Both La and %La-v, as an initial value in the intensive care unit, may play an important role in planning the postoperative management of patients undergoing open-heart surgery.

Background. It is critical to evaluate the anastomotic quality of coronary artery bypass grafting (CABG) in the operating room. The aim of this study is to determine the validity of intraoperative flow measurement for predicting the quality of CABG by comparison with the postoperative quantitative angiographic evaluation of the grafts. Methods. Eighty-two grafts, including 37 internal thoracic arteries, were examined intraoperatively with a transit-time flowmeter. Coronary angiograms were performed 14 +/- 5 days after CABG to quantify the diameters at the toe, heel, and anastomosis proper of the grafts. Results. There were significant differences between patent and nonpatent grafts in all intraoperative flow parameters. However, the only cut-off value to distinguish patent from nonpatent was a fast Fourier transformation (FFT) ratio of 1.0. FFT is the ratio of powers of the fundamental frequency and its first harmonic. Postoperative quantitative angiography indicated that the stenosis was greatest at the heel of the anastomosis. The degree of stenosis at the heel of the anastomosis alone correlated significantly with intraoperative mean flow values. Conclusions. Fast Fourier transformation analysis of flow measurement may be useful to differentiate patent grafts intraoperatively. Intraoperative flow measurement may predict the most stenotic part of the anastomosis. (C) 2001 by The Society of Thoracic Surgeons.

Anastomotic quality of coronary artery bypass grafting is directly associated with peri-operative and long-term clinical results. In this study, we investigated a cut-off value for intra-operative flow measurement. This value could be of use to a surgeon in determining the anastomotic quality of grafts. Intra-operative transit-time flow variables (mean flow, pulsatility index, % efficiency, fast Fourier transformation (FFT) of the flow curve) and the 2-week post-operative angiographic findings were examined in 66 coronary artery bypass grafts, including 33 internal thoracic arteries. There were significant differences between patent and non patent grafts in all of the intra-operative flow parameters. Only the FFT ratio, the ratio of powers of the fundamental frequency and its first harmonic, could be utilized as a cut-off value to distinguish patent from non patent grafts. All stenotic or occluded grafts showed an intra-operative FFT ratio of &lt 1.0, while all patent grafts yielded a ratio of =1.0. Based upon these results, we concluded that power spectral analysis of flow measurement might be useful for intra-operative differential diagnosis of the anastomotic quality in coronary artery bypass grafting. © 2001, SAGE Publications. All rights reserved.

The Gyro Pump C1E3 incorporates a double-pivot bearing system as a completely sealless centrifugal pump. The male pivot is made of alumina ceramic, and the female is made of polyethylene. Therefore, the durability of this pump depends upon morphological changes of the female polyethylene pivots, which we examined after clinical usage in the present study. We examined 30 pumps, which were used for cardiopulmonary bypass (CPB), in terms of weight, depth, and surface roughness of the female polyethylene pivots. To determine changes caused by clinical use, we also examined 10 pumps of the same lot numbers with the pumps clinically used and stocked in the factory. There were no significant changes in weight of top and bottom pivots. Also, there was no significant difference in depth and surface roughness of the top pivots. However, there was a significant increase in depth and a decrease in surface roughness of the bottom pivots from clinical use. The results revealed that the bottom pivot, rather than the top pivot, is subject to mechanical deformation by clinical use of the Gyro Pump for CPB. Since morphological changes of the bottom pivot may result from spinning of the impeller at the bottom contact phase, the magnetic coupling distance may need to be increased to obtain more stable spinning of the impeller in a routine CPB.

Background. The right gastroepiploic artery (GEA) has been used as the second reliable arterial graft for coronary artery bypass grafting (CABG). However, concern regarding the flow competition with the recipient coronary artery has remained. Methods. An application of in situ GEA grafting to the right coronary artery (RCA) was studied by using a theoretical model, The theoretical model of CABG was given variables; ie, the diameters and the lengths of both in situ GEA and proximal segment of the RCA, and the degree of proximal stenosis in the RCA. According to the range of these variables obtained from clinical data,the ratio of the GEA now to the flow of the RCA. distal to the anastomosis was calculated, Results. Main factors to determine the flows in the two parallel paths were the inner diameters of both vessels, and the degree of the proximal stenosis, When the inner diameters of the GEA were 0.5 mm larger than that of the RCA,the GEA carried more than 50% of the total flow of the RCA distal to the anastomosis despite a moderate stenosis in the RCA. When the inner diameter of the GEA was equal to, or 0.5 mm smaller than, that of: the RCA, the GEA flow was dominated by the native RCA flow unless the proximal stenosis was critical. Conclusions. if the inner diameter of the GEA is 0.5 mm larger than that of the RCA, CABG with the GEA can be applied more widely. If not, the application would basically be limited. (C) 2000 by The Society of Thoracic Surgeons.

症例は79歳,男性.心筋梗塞後の経過観察中腹部腫瘤を触知し腰痛を訴え,最大径60mmに及ぶ腹部大動脈瘤と診断された.術前精査にて冠動脈に左主幹部を含む高度狭窄病変,左基底核・前頭葉の脳梗塞,頭蓋内両側内頸動脈の狭窄を認めた.冠動脈バイパスと腹部大動脈瘤切除の同時手術の適応と考えられたが,脳血管障害の重大なリスクを伴うため,人工心肺を使用せず心拍動下で冠動脈バイパスを施行し,引き続き腹部大動脈瘤手術を行った.左冠動脈第一対角枝には左内胸動脈を,右冠動脈#3には右内胸動脈を左橈骨動脈にて延長し作成した合成グラフトを各々吻合した.グラフト流量を測定し循環動態が安定していることを確認後,腹部大動脈瘤を切除,Y型人工血管にて再建した.合併症なく術後経過良好にて退院に至った.重症冠病変を有する腹部大動脈瘤の治療戦略の一つとして,人工心肺非使用心拍動下冠動脈バイパスと人工血管置換の同時手術は,体外循環による侵襲を回避でき,特に他の合併症を有しリスクの高い患者には有用であると考えられる.

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, the Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart (TAH), 2 week screening tests for anti-thrombogenecity, and a 1 month system feasibility study. Based upon these results, a metallic prototype, the Gyro PI700 series, was subjected to long-term in vivo left ventricular assist device (LVAD) studies of over 1 month. The Gyro PI700 series has the same inner dimension and same characteristics of the Gyro PI 601 such as an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI metallic pump is also driven with the Vienna DC brushless motor actuator like the PI 601. The pump-actuator package was implanted in 3 calves in the preperitoneal space, bypassing from the left ventricular (LV) apex to the descending aorta. Case 1 achieved a 284 day survival. Case 2 was euthanized early at 72 postoperative days as a result of the functional obstruction of the inlet port due to the excessive growth of the calf. There was no blood clot inside the pumps of either case. Case 3 is on-going (22 days on July 24, 1998). During these periods, all cases showed no physiological abnormalities. In conclusion, the PI700 series pump has excellent results as a long-term implantable LVAD.

The maze procedure may be performed in combination with valve operations to treat chronic atrial fibrillation associated with valve dysfunction. Although we initially used the modified Cox maze III procedure, a more limited partial maze procedure is now preferred because the left atrium might be considered as the electrical impetues for atrial fibrillation. In this study we compared the results of 30 patients (group I) who underwent the full biatrial modified Cox maze III and 20 (group II) patients the partial maze procedure. While the rates of restored sinus rhythm were the same in both groups at B-month follow-up (I: 83.3%, vs II: 80%), the following advantages were noted in the patients undergoing the partial maze procedure: shorter operative times, lesser elevations of creatine phosphokinase, lower rate of blood transfusion, lower rate of junctional rhythm soon after the operation, and a higher P wave in those patients with restored sinus rhythm. The effectiveness of the partial maze procedure seems equal to that of the biatrial modified Cox maze III procedure for atrial fibrillation associated with valve disease. The partial maze procedure is simple and less invasive, and thus might be applied more frequently as an additional procedure to valve operations without additional risk.

IABPを要したCABG症例におけるU波とQT間隔分散 (QTD) の意義を明らかにするために, 30例 (男: 女=26: 4, 61.1±10.1歳, IABP57.7±37.9時間) の周術期心電図を検討した. 術前U波・QTDの出現率は, 術前IABP挿入13例で53.8%, 38.4%, 術中挿入17例で52.9%, 76.4%であり, 前より有意に減少し, CABG・IABP併用の心筋保護効果が示された. IABP抜去直後U波・QTDが非出現の10例全例で退院前心電図が術前と比し不変か改善を示した. 一方退院前心電図の増悪症例20例では, 75%でIABP抜去直後のU波出現誘導と退院前増悪誘導が一致した. 残り25%では, 全例QTDを認めた. 今回分析したU波・QTDという心電図変化は, 可逆的に出現し, IABPを要するCABG周術期において, 心筋虚血状態を判断する上で極めて重要と考えられた.

A totally implantable centrifugal artificial heart has been developed in which a pivot bearing supported centrifugal pump is used as a blood pump. The following have been adopted as blood contacting materials in our pump: titanium alloy (Ti-6Al-4V) for the housing and impeller, alumina ceramic (Al2O3) for the male pivots, and ultrahigh molecular weight polyethylene (PE) for the female pivots. Greater antithrombogenicity is required for an implantable blood pump. To examine the thrombogenicity of these materials, we evaluated in vitro platelet adhesion and activation, which may play key roles in thrombogenesis on foreign surfaces. Ti-6Al-4V, Al2O3, and PE were compared with polycarbonate (PC), silicone carbide (SiC), and pure titanium (pTi). Platelet adhesion was assessed using monoclonal antibody (CD61) directed against glycoprotein IIIa. Platelet activation was evaluated by measuring P-selectin (GMP-140) released from irreversibly activated platelets. Each material with a surface area of 16.6 cm(2) was incubated with 2.5 ml of plasma or 2.5 ml of heparinized fresh whole blood for 3 h at 37 degrees C. The optical density (OD) at a wavelength of 450 nm for CD61 was 0.93 +/- 0.35 in PC, 0.34 +/- 0.13 in PE, 0.27 +/- 0.13 in pTi, 0.26 +/- 0.01 in Al2O3, 0.21 +/- 0.04 in SiC, and 0.12 +/- 0.12 in Ti-6Al-4V. The GMP-140 levels of the tested materials were not significantly different from the control value (45.9 +/- 7.2 ng/ml). These results indicate that Al2O3, PE, and Ti-6Al-4V, which are incorporated into our implantable centrifugal pump, have satisfactory antithrombogenic properties in terms of platelet adhesion. However, platelet activation by any material was not observed under the static condition in this study.

A miniaturized Gyro centrifugal pump has been developed to be incorporated into a totally implantable artificial heart. The Gyro PI (permanently implantable) model is a pivot bearing supported centrifugal pump with a priming volume of 20 ml. With the miniaturized actuator, the pump-actuator package has a height of 53 mm, a diameter of 65 mm, and a displacement volume of 145 ml. To evaluate the hemocompatibility and efficiency of the Gyro PI pump system, a plastic prototype (Gyro PI-601) was implanted into a bovine model as a left or right ventricular assist device (LVAD or RVAD), bypassing from the left ventricular apex to the descending aorta or from the right ventricular infundibulum to the main pulmonary artery. The calves were anticoagulated with heparin to maintain activated clotting times from 150 to 200 s. Four calves were supported for 23, 24, and 50 days in the LVAD studies, and 40 days in the RVAD study. The first calf died due to intrathoracic bleeding associated with sepsis. The second calf was euthanized for a low now rate less than 2 L/min due to an obstructed inflow with growing pannus. The third and fourth calves were euthanized as scheduled. Renal and hepatic functions remained normal, and plasma free hemoglobin values were less than 8 mg/dL throughout the experiments. The fourth case showed now rates of 4.83 +/- 0.57 L/min, input power of 6.16 +/- 0.49 W, and the inside temperature of the actuator of 43.5 +/- 0.52 degrees C. The pumps implanted in the fourth calf demonstrated no thrombus formation at the autopsy. These in vivo experiments revealed that the Gyro PI pump can provide adequate now as an easily implantable, efficient, antithrombogenic, and nonhemolytic centrifugal LVAD or RVAD with miniaturized actuators.

The rotary blood pump will be an implantable left ventricular assist device (LVAD) in the near future. However, the best control method and the interrelationship between the rotary blood pump and native heart functions are unclear. An estimation was made of the native heart cardiac output from the change of an LVAD's outflow waveform. The mock circulation loop was composed of an aortic compliance chamber, left arterial chamber, total artificial heart as a native heart, and a rotary blood pump that was placed as an LVAD with left ventricular drainage. The fast Fourier transform (FFT) technique was utilized to analyze the LVAD's outflow waveform aid calculate the pulse power index (PPI) to examine a relation between tl le PPI and total artificial heart (TAH) output. The PPI increased with the increase of the TAH output; there was a positive correlation, and there was an inverse correlation between the PPI and the assist ratio. From this viewpoint, an estimation of the pulsatility change of the LVAD's outflow wave may indicate the native cardiac output.

The significant amount of regurgitation produced by a stopped rotary blood pump is one of the major considerations for its use as an implantable left ventricular assist device (LVAD), especially if the pump accidentally stops. The installation of a valve is an option for the solution of this potential problem, However, this option may lead to thrombogenic problems, particularly if the valve motion is restricted, This in vitro study analyzes the value performance and assesses the credibility of a rotary blood pump valve, A pulsatile pump was used as the natural heart and a centrifugal pump as the LVAD. The valve was positioned into the LVAD outflow, In the low speed range (<1,000 rpm in this test condition), normal valve motion was maintained. Also, the valve model provided a higher mean bypass flow than the model without a valve due to reduced regurgitation. However, the valve motion was drastically restricted when in the high speed range (>1,600 rpm in this condition). The pulsatile mode was applied to the LVAD by periodically changing the impeller speed (40 bpm); subsequently, a constant valve motion could be provided. A possibility exists that this pulsatile mode application could eliminate thrombosis formation around the valve. A conclusion was made that the combination of a valve and an LVAD in a pulsatile mode is considered to be a unique safety system for a rotary blood pump.

The gyro pump was developed as an intermediate-term assist pump (C1E3) as well as a long-term centrifugal ventricular assist device (VAD). The antithrombogenic design concept of this pump was confirmed throughout three 1 month ex vivo studies. The normalized index of hemolysis (NIH) of this gyro C1E3 model was lower than that of the BP-80. In the next step, a miniaturized centrifugal blood pump (The Gyro permanently implantable model PI-601) has been developed for use as a permanently implantable device after design optimization. A special motor design of the magnet circuit was utilized in this system in collaboration with the University of Vienna. The priming volume of this pump is 20 mL. The overall size of the pump actuator package is 53 mm in height, 65 mm in diameter, 145 mi of displacement volume, and 305 g in weight. This pump can provide 5 L/min against 120 mm Hg total pressure head at 2,000 rpm. The NIH value of this pump was comparable to that of the BP-80. The gyro PI-601 model is suitable for a VAD. The expected life from the endurance study is approximately 8 years. The evolution from C1E3 to the PI-601 converts this pump to a totally implantable centrifugal pump. Recent technologic advances in continuous flow devices are likely to realize a miniaturized and economical totally implantable VAD.

A totally implantable centrifugal artificial heart has been developed using a miniaturized pivot bearing supported centrifugal pump (Gyro PI pump). The authors report current progress in its development. The Gyro PI-601 has a priming volume of 20 ml, weighs 100 g, has a height of 60 mm, and has a diameter of 65 mm. This pump can provide 8 L/min against 150 mmHg at 2,250 rpm. It is driven by an miniaturized DC brushless motor with the coils fixed in a plastic mold that is waterproof and made of titanium (weight, 204 g height, 18 mm diameter, 65 mm). In this centrifugal artificial heart, two Gyro PI pumps are implanted independently to replace cardiac function without resecting the native heart. Its anatomic and surgical feasibility were confirmed experimentally. The Gyro PI-601 was implanted as a right or left ventricular assist device in the preperitoneal space of five calves. All five tests proceeded without any thromboembolic symptoms. One of five tests was extended more than 1 month to confirm the long-term feasibility of the Gyro PI-601 pump system. Based on the satisfactory results of the in vivo tests, the material conversion of the Gyro PI from polycarbonate to titanium alloy (Ti-6A1-4V) was undertaken to improve its biocompatibility for long-term implantation.