Low-dose protamine based on heparin-protamine titration method reduces platelet dysfunction after cardiopulmonary bypass.

OBJECTIVE: The heparin-protamine titration method that uses the Hepcon hemostasis management system (Medtronic HemoTec Inc, Englewood, Colo) reduced blood loss in cardiac surgery in previous reports, but the mechanism is not fully understood. This study tests the hypothesis that reduced protamine administration preserves platelet function in human cardiac surgery. METHODS: Platelet count, alpha-granule secretion, and aggregation to thrombin before and after cardiopulmonary bypass in human beings were evaluated. In the control group (n = 14), a fixed dose of protamine (3 mg/kg) was administered. In the titration group (n = 20), protamine doses were based on the heparin concentration measured by the Hepcon system. RESULTS: Heparin concentrations before protamine administration were higher in the titration group (P =.0012), but protamine doses of patients in the titration group were markedly lower than those of the control group (P <.0001). During protamine infusion at a rate of 0.3 mg. kg(-1). min(-1), the percentage of granule membrane protein-140-positive platelets significantly increased in the control group compared with the titration group (18.8% +/- 8.6% vs 13.0% +/- 5.3%, P =.0188). After protamine administration, aggregation of washed platelets to thrombin recovered almost to the preoperative level in the titration group; however, it remained lower in the control group (20% +/- 20% vs 55% +/- 18%, P =.0009). CONCLUSION: Low-dose administration of protamine, based on a heparin-protamine titration method, restores not only the blood coagulation but also the platelet responses to thrombin and attenuates platelet alpha-granule secretion during heparin neutralization. Overdose of protamine activates platelets and may predispose patients to excessive bleeding after cardiac surgery.

Influence of bypass grafting to the infarct artery on late potentials in coronary operations.

BACKGROUND: Late potentials (LPs) after myocardial infarction identify the risk of arrhythmic events and sudden death, and the absence of anterograde flow in the infarct-causing occluded coronary artery frequently is associated with LPs on signal-averaged electrocardiography. The present study was designed to clarify the influence of revascularization of the infarct artery on the LPs in the late course after myocardial infarction. METHODS: We studied 21 patients after myocardial infarction with positive LPs who had at least one occluded infarct coronary artery. We investigated the LPs on signal-averaged electrocardiograms on the day of elective coronary artery bypass grafting (CABG) and 1 week after CABG. RESULTS: There were 25 infarct arteries in the study patients, 13 of which were grafted. The positive LPs disappeared soon after CABG in 13 patients, 10 of whom had grafts to all of the infarct arteries. The LPs persisted in 8, who received no graft to the infarct artery. One week after CABG, the LPs were still present in 4, all of whom had no graft to the infarct right coronary artery. CONCLUSIONS: In patients with positive LPs late after myocardial infarction, grafting to the infarct artery eliminated the LPs soon after CABG.

Right thoracotomy as an alternative for redo mitral valve replacement and concomitant repair of the tricuspid valve.

BACKGROUND: We report the results of a right thoracotomy for reoperation on the mitral plus concomitant procedures. Access to aorta or repair of other lesions by this approach is controversial. EXPERIMENTAL DESIGN AND SETTING: Retrospective study. Institutional practice (University of Tsukuba Hospital, Tsukuba Japan). METHODS: Until 1995, 9 patients underwent right thoracotomy for mitral reoperation. The indication for this approach was no retrosternal space with the pericardium left open. Seven patients had deteriorated bioprosthesis, 1 periprosthetic valve leakage, and 1 re-stenosis. Four were associated with moderate tricuspid regurgitation. Operations were performed under fibrillation. Cardioplegia was used in 1. RESULTS: Through thoracotomy, 4 underwent mitral valve re-replacement, and 4 mitral valve re-replacement plus tricuspid annuloplasty. One was abandoned because of severe pleural adhesion. No neurological injury, or perioperative myocardial infarction occurred. CONCLUSIONS: The right thoracotomy was an effective alternative to repeat sternotomy for redo mitral valve operation. Also, concomitant repair of the tricuspid valve could be safely done by this approach.

Acute effects of exercise on muscle MRI in peripheral arterial occlusive disease.

The midcalf muscles of eight patients who had peripheral arterial occlusive disease were evaluated by exercise MRI before and after bypass surgery or percutaneous transluminal angioplasty. MRI showed a high intensity of these muscles, especially the posterior muscles, after exercise in all patients before intervention. The mean T2 relaxation time was maximal immediately after exercise (tibialis anterior, T2 = 30.8 ms; soleus, T2 = 36.2 ms; gastrocnemius, T2 = 32.8 ms) and then gradually decreased to the preexercise level. The difference in the T2 relaxation time of the soleus between immediately after exercise and at rest was smaller along with improvement of ankle pressure indices (API) after successful intervention (mean T2 difference: 4.91 and 0.72 ms (p < .001); mean API: 0.54 and 0.86 (p < .001) before and after intervention, respectively). The mean resting midcalf T2 relaxation time was significantly higher after intervention (tibialis anterior, T2 = 28.4 and 29.5 ms (p < .05); soleus, T2 = 31.4 and 32.9 ms (p < .05); gastrocnemius, T2 = 29.5 and 31.1 ms (p < .01) before and after intervention, respectively). T2 relaxation time may be a useful quantitative parameter in peripheral arterial occlusive disease as well as in other muscle studies.

Pseudoaneurysm of the subclavian artery due to Xanthomonas pneumonia in a patient with acute myeloid leukemia: its rupture treated by transcatheter coil embolization.

A 52-year-old male with acute myeloid leukemia developed pseudoaneurysm of the subclavian artery. Pneumonia due to Xanthomonas maltophilia, which was multi-drug resistant, progressed to a lung abscess even under administration of antibiotics. This lung infection contiguous to the left carotid and subclavian arteries was suggested to have caused the pseudoaneurysm of the subclavian artery. The rupture of the aneurysm by penetration to the trachea amounted to about 1,000 ml of bleeding; fortunately the bleeding ceased spontaneously. Nonetheless, an emergency transcatheter coil embolization prevented re-bleeding. Endovascular treatment should be considered especially for aneurysms which develop in patients with underlying diseases.

Species differences in erythrocyte mechanical fragility: comparison of human, bovine, and ovine cells.

The erythrocyte destruction rate under constant shear stress was measured to clarify species differences in red blood cell (RBC) mechanical fragility between human, bovine, and ovine cells. Blood was collected from healthy donors by venipuncture. RBC age fractionation was performed by high speed centrifugation (20 min at 12,000 g). Relatively young, middle, and old age RBCs was suspended in Dulbecco's phosphate buffered saline to adjust the hematocrit to 35%. Uniform shear stress was applied to each sample contained in a concavo-convex Couette flow testing machine. Young and old aged samples were exposed to 300 dyne-sec-cm2 for 0 and 15 min. Middle aged samples were exposed to 300 dyne-sec-cm2 for 0, 5, 10 and 15 min. Liberated hemoglobin was estimated by tetramethylbenzidine colorimetric measurement and the erythrocyte destruction rate was calculated. Older samples had a higher hemolysis rate than younger samples in every species. The destruction under constant shear stress is approximately linear in time. Mechanical fragility of ovine and bovine RBCs was 1.8 and 0.5 times as large as human RBCs, respectively. These values could serve as universal standards when extrapolating animal hemolysis data for any blood pump to predict its safety and biocompatibility in human clinical trials.

Fluid dynamic characteristics of monopivot magnetic suspension blood pumps.

A monopivot magnetic suspension blood pump is a centrifugal pump under development with a magnetic suspension and a ceramic pivot to support the impeller with minimum contact. The pump size has been reduced by implementing a direct impeller drive mechanism in place of a magnetic coupling and motor. Flow visualization studies revealed that high shear, which seems to be closely related to hemolysis, concentrates in boundary layers near the walls. This implies that fluid dynamic shear can be reduced not by widening the gap, but by reducing the impeller velocity. Therefore, compared with the results of the previous semi-open curved vane impeller model, impeller velocity was reduced by 30% with a closed impeller having radial straight vanes, and smaller impeller/housing gaps. The volute shape around the impeller tip was also changed such that the outflow from the impeller enters along the center plane of the volute. To examine the effect of the improvements, hemolysis testing was conducted and found that the newly developed closed impeller model generated a lower level of hemolysis than the previous semi-open impeller model.

Method of noninvasive and continuous hemolysis/thrombogenesis measurement by laser photometry during artificial heart development.

The purpose of this research is to propose and develop a method to measure hemolysis and thrombogenesis non invasively and continuously to aid in development of an artificial heart. Generally, the optical absorption rate of hemoglobin is influenced by oxygen saturation except at the isosbestic point, which is not influenced by oxygen saturation. The authors, therefore, used an 805 nm laser diode, an optical spectrum analyzer to obtain greater accuracy. An experimental blood circuit system was constructed using a Bio-Pump, Tygon tubing, a soft shell reservoir, and an optical measurement system. Experimental settings for monitoring hemolysis were as follows; blood volume 200 ml, blood flow 6 L/min, and afterload 200 mmHg. Blood was sampled six times (0, 30, 60, 120, 180, and 240 min), and hemolysis in each sampled was measured using a colorimetric method. Comparing continuous laser measurement data with the sample data, an adequate correlation is obtained, proving that the dynamic trend of hemolysis could be continuously measured. Furthermore, to analyze the process of thrombogenesis, simple experiments were performed using blood neutralized by protamine. As a result, the authors could see the process of thrombogenesis as it occurred and could confirm that this method is able to dynamically detect hemolysis and thrombogenesis.

Upper extremity vein thrombosis: etiologic categories, precipitating causes, and management.

Although an increasing incidence of upper extremity venous thrombosis (U/E-DVT) has been reported, a relative paucity of information regarding the etiologic categories, precipitating causes, and proper management for this disorder is available. To settle on a strategy for the management of U/E-DVT, retrospective analyses were performed using records from the authors' hospital. In 12 patients (seven men, five women), 61 (mean) years of age, diagnosed as having symptomatic venography-proved U/E-DVT and followed up for 41 (mean) months, etiologic factors, precipitating causes, treatments, and outcomes were retrospectively analyzed. As etiologic factors, five of the patients had neoplastic disease, one had hemodialysis, and two had transvenous pacemaker implantations. Among various precipitating causes of U/E-DVT, hypoproteinemia was most frequently noted (67%). Various types of therapeutic management were selected: from thrombolysis with urokinase in six, balloon angioplasty in two, thrombectomy in two, and venous bypass surgery in one patient. Pulmonary embolism did not occur in any of the patients and only three of them complained of mild intermittent arm swelling during the follow-up period. Four patients died of neoplastic disease or heart failure (three within the first 6 months). This study, though limited, suggests that the rate of mortality depends on multiple underlying medical problems in U/E-DVT patients. Low incidences of late postthrombotic sequelae and pulmonary embolism were noted in this series. Symptomatic U/E-DVT patients could be managed conservatively with a revised supplementary therapy for their precipitating causes of U/E-DVT.

Evaluation of stress on the autonomic nervous system of patients on mechanical circulatory assist.

PURPOSE: The power density values of high (HF; 0.15 to 0.4 Hz) and low frequency (LF; 0.04 to 0.15 Hz) components of arterial pressure were adopted for evaluation of stress on the autonomic nervous system of patients supported by mechanical circulatory assist. METHODS: Power spectral analysis (PSA) of arterial pressure signals was carried out, and trends in changes in the spectral components were observed in 12 patients on mechanical circulatory support (IABP and/or PCPS) and without the support (n=10). RESULTS: The normalized LF was depressed initially and increased gradually in both groups of patients except for four patients on mechanical circulatory assist. Three patients among them consequently died. CONCLUSIONS: Depressed LF represented marked stress on ANS and prolongation of the depression was related to poor outcome of patients. PSA of systemic blood pressure offers a reasonable tool for evaluation of stress on the ANS and for prediction of the prognosis of patients with circulatory assist devices.

Effect of left ventricular assist device on circulatory autonomic nervous activity.

PURPOSE: For evaluation of the autonomic nervous system (ANS) activity of patients with mechanical circulatory support including LVAD, IABP and PCPS, arterial pressure variability (APV) was examined. APV is the power density values of pressure signals. High frequency (0.15 to 0.4 Hz) and low frequency (0.04 to 0.15 Hz) components of APV are regarded as a function of the autonomic nervous system. METHODS: Arterial pressure signals were acquired every 2 hours at 100 Hz for 6 minutes. Power spectral analysis was carried out, and APV was observed in 18 patients with IABP and/or PCPS. APV was also observed in 3 patients with LVADs (Xemex, Zeon Medical, Japan) before their discharge from ICU for transfer to another hospital for cardiac transplantation. RESULTS: Although the value gradually increased in 18 patients with IABP and/or PCPS, sustained low values of LFAnorm of APV in 6 patients were related to prolonged mechanical support, and 4 patients among them died consequently. The normalized power spectral component with low frequency (LFAnorm) was maintained at relatively high values in 3 patients with LVADs. CONCLUSION: The study results suggest that power spectral analysis of systemic arterial pressure offers a reasonable means for the evaluation of the severity of patient cardiovascular condition and for the prediction of clinical outcome. It also suggested that LVAD support exerts a favorable effect on ANS in patients with severe heart failure before cardiac transplantation.

Mitral reoperation via right thoracotomy in a patient with pulmonary hypertension.

A 62-year-old woman with pulmonary hypertension underwent mitral valve re-replacement through right thoracotomy. Severe adhesion occurred to the right lung. During pleural dissection the lung collapsed under single-lung ventilation, rapidly elevated pulmonary vascular resistance caused hemodynamic instability. When pulmonary hypertension is preoperatively present, this approach under single-lung ventilation is not recommended.

Aortic dissection extending from ductus diverticulum aneurysm.

We report the case of a 28-year-old woman with type B chronic aortic dissection extending from a ductus diverticulum aneurysm. The patient was successfully treated by interposition of a Hemashield 26-mm woven Dacron graft with a left posterolateral thoracotomy approach. Circulatory arrest through profound hypothermia and short retrograde cerebral circulation were employed during proximal anastomosis of the graft.

Atrial fibrillation after coronary artery bypass grafting. An increase in high-frequency atrial activity in patients with right coronary artery revascularization.

The increase in atrial high-frequency activity has been reported as a marker of the risk of paroxysmal atrial fibrillation. The presence of proximal right coronary artery disease is a predictor of atrial fibrillation after bypass surgery, however, the potential mechanism remains controversial. In this study, high-frequency atrial activity to clarify the electrophysiologic background for the predisposition to have proximal right coronary artery disease leading to atrial fibrillation after coronary revascularization was investigated. Before and soon after coronary revascularization, frequency analyses were performed on the 100 ms segment at the end of signal-averaged P waves in 22 patients with right coronary artery disease as opposed to the 23 patients without disease. Under the spectrum curve, area ratio (AR50) and magnitude ratios (MR) were calculated as follows; AR50 = (area 20-50 Hz/0-20 Hz) x 100, and MR = (magnitude at 20, 30, 40 and 50 Hz, respectively/maximal magnitude) x 100. In patients with proximal right coronary artery disease, high-frequency atrial components increased significantly in the 20 to 50 Hz range after coronary revascularization, and the incidence of postoperative atrial fibrillation was higher than in those without disease. In patients without right coronary artery disease, the frequency distribution of P waves was unchanged. Postoperatively, the two groups showed the same atrial frequency distribution. This data suggests that the increase in high-frequency atrial activity after right coronary artery revascularization might be associated with the pathogenesis of postoperative atrial fibrillation.

Aortic dissection complicating cardiac surgery in a patient with calcified ascending aorta.

Aortic dissection is a rare but devastating complication of cardiac surgery. Adequate and early diagnosis of intraoperative aortic dissection and quick therapeutic decision making are the keys for saving patients in such cases. We describe the case of a 68-year-old man referred for CABG and mitral valve replacement with severe calcification of the ascending aorta. Intra-operative transesophageal echocardiography was useful for diagnosis of intra-operative aortic dissection and malperfusion of the true lumen. Immediate switching of the arterial perfusion site established flow in the true lumen with prompt subsidence of the expanded false lumen. CABG, mitral valve replacement and graft replacement of the ascending aorta could be simultaneously performed in this patient.

[Stickler syndrome with rapidly progressive mitral valve regurgitation: report of a case].

A 36-year-old man with Stickler syndrome who underwent mitral valve replacement for rapidly progressive mitral regurgitation due to prolapse of an anterior leaflet. Stickler syndrome is a relatively rare condition caused by a defective collagen gene and characterized by high myopia, sensorineural-hearing deficit and flattened facial features. The prevalence of mitral valve prolapse in Stickler syndrome is reported to be much higher than in the general population because of its connective tissue dysplasia. Mitral regurgitation rapidly and refractorily progresses. Prompt surgical treatment should be recommended to mitral regurgitation in Stickler syndrome, and mitral valve replacement with a prosthetic valve is a better selection than mitral valve plasty for tissue fragility.

[A percutaneously controllable pulmonary artery banding device: clinical application].

An optimal pulmonary artery banding is often difficult with a conventional banding technique. It often requires readjustment after closing the chest. So we developed a percutaneously controllable pulmonary artery banding device and applied it in three patients. This device consists of silicone balloon being pasted on a reinforced silastic plate and silicone reservoir. The balloon is applied around the pulmonary artery and the reservoir is implanted subcutaneously. The control of the banding is accomplished percutaneously through the reservoir using a needle with fluid-filled syringe. This device worked successfully in two patients for percutaneous readjustment of pulmonary constriction and congestive heart failure was decreased. This device may offer proper constriction of the pulmonary artery without any surgical procedures after banding and may reduce surgical morbidity and mortality of sick children.

[A case of cor triatriatum with atrial septal defect in an adult].

A surgical treatment of a 54 year-old female with cor triatriatum was reported. Two dimensional echocardiography had demonstrated an abnormal septum in the left atrium. The abnormal septum had a 2 x 1 cm fenestration and existed between the left and right pulmonary veins. Preoperatively, we had misjudged the septum as ASD and misdiagnosed this case as PAPVC. During surgery we found that there was the accessory atrial chamber posterior to the true ASD. The accessory chamber received right pulmonary veins and connected to the left atrium. The left pulmonary veins connected to the left atrium normally behind the abnormal septum. We diagnosed this case as Lucas-Shmidt IIIA1 type cor triatriatum with ASD. The abnormal septum was resected, and the ASD was closed with a bovine pericardium. The postoperative course was uneventful and she was discharged 19 days after the operation.

[A surgical case of atrial septal defect with myotonic dystrophy].

A case report is presented of a 16-year-old woman with myotonic dystrophy, who required open-heart surgery for an atrial septal defect. We successfully repaired an atrial septal defect using normothermic cardiopulmonary bypass and electrically maintained ventricular fibrillation. Anesthesia using fentanyl, vecronium and isoflurane was uneventful and there were no postoperative complications. Anesthetic agents must be selected with care, and ventilation requires meticulous attention.

[Right thoracotomy to approach mitral or tricuspid valve in reoperation].

Four patients underwent mitral valve re-replacement, and required tricuspid annuloplasty in two, through a right thoracotomy. There was no major postoperative morbidity and recovery was full and uneventful. The indications for selection of this approach were isolated mitral valve disease or combined tricuspid and mitral valve disease, severe adhesion between heart and sternum on CT scan, intact aortic valve and no severe reduction of respiratory function. We recommend right thoracotomy to approach atrioventricular valves in selected situations in patients for reoperations.