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Biomedical subjects

S H Chu

Publications and source records attributed to S H Chu.

At least 55 records · Page 3Linked to original sources
PubMed2000

Simple method of hemostasis in implantation and explantation of HeartMate left ventricular assist device.

We described a simple method of hemostasis in implantation and explantation of HeartMate left ventricular assist device. Wrapping of the inflow cannula, outflow conduit and outflow graft with Vascutek tube graft can localize the bleeding due to patient's coagulopathy, imperfect coating and device defect. During explantation, bivalving the tube graft, leaving the graft in place and no-touch of the adhesion between graft and soft tissue can minimize the dissection and prevent the potential bleeding.

Adult↗
PubMed2000

Paroxysmal supraventricular tachycardia in identical twins with the same left lateral accessory pathways and innocent dual atrioventricular pathways.

We report on 16-year-old, female identical twins who both have atrioventricular reentrant tachycardia caused by the same left lateral atrioventricular accessory pathway. The Kent pathway in twin A was a unidirectional retrograde accessory pathway. A manifest Kent pathway was demonstrated in twin B. Both pathways were successfully ablated by radiofrequency (RF) energy and without recurrence. In addition, innocent dual AV nodal pathways were shown in both patients. These findings suggest that genetic factors may play a role in the pathogenesis of the formation of accessory atrioventricular pathways and dual AV nodal pathways.

Adolescent↗
PubMed2000

Role of electrophysiological studies and arrhythmia intervention in repairing Ebstein's anomaly.

BACKGROUND: Repairing Ebstein's anomaly without correction of associated arrhythmia may result in sudden death. Catheter or surgical ablation is indicated for various symptomatic tachyarrhythmias in Ebstein's anomaly. METHODS: Between October 1973 and October 1997, 30 patients with Ebstein's anomaly underwent surgical repair in our hospital. Tricuspid valve replacement was performed in 13 patients, tricuspid annuloplasty and valvuloplasty in the remaining 17 patients. Preoperative electrophysiological studies were performed in 11 patients after 1980. Concomitant arrhythmia ablation was done in 10 patients: 4 for Wolff-Parkinson-White syndrome, 2 for atrioventricular (AV) nodal reentrant tachycardia, one for ventricular tachycardia and 3 for paroxysmal atrial flutter and fibrillation. RESULTS: No mortality or major morbidity occurred in those patients undergoing arrhythmia intervention. There were 7 deaths in total; 6 died suddenly, and the other died of purulent mediastinitis. None of the 6 sudden deaths underwent preoperative electrophysiological evaluation. The functional recovery was good in all survivals. CONCLUSIONS: We conclude that detailed preoperative electrophysiological evaluation in patients with Ebstein's anomaly is mandatory. Aggressive surgical intervention of the associated arrhythmias in addition to anatomic correction can reduce the sudden death in Ebstein's anomaly.

Adolescent↗
PubMed2000

Turbulence characteristics downstream of bileaflet aortic valve prostheses.

This study was focused on a series of in vitro tests on the turbulent flow characteristics of three bileaflet aortic valves: St. Jude Medical (SJM), CarboMedics (CM), and Edwards Tekna (modified Duromedics, DM). The flow fields of the valves were measured in a pulsatile flow model with a laser-Doppler anemometer (LDA) at the aortic sinus area downstream of the valves. The heart rate was set at 70 beats per minute, the cardiac output was maintained at 5 liters per minute, and the aortic pressure wave forms were kept within the physiological range. Cycle-resolved analysis was applied to obtain turbulence data, including mean velocity, Reynolds stresses, autocorrelation coefficients, energy spectral density functions, and turbulence scales. The Reynolds shear stresses of all three valves induced only minor damage to red blood cells, but directly damaged the platelets, increasing the possibility of thrombosis. The smallest turbulence length scale, which offers a more reliable estimate of the effects of turbulence on blood cell damage, was three times the size of red blood cells and five times the size of platelets. This suggests that there is more direct interaction with the blood cells, thus causing more damage.

Aortic Valve↗
PubMed2000

Combined heart transplantation and resection of dissecting aneurysm of ascending aorta and aortic arch: a case report.

A 21-year-old male patient had suffered from palpitation and exertional dyspnea since October, 1997. He was admitted to our hospital, and a series of examinations were performed. Chest computed tomography (CT) revealed marked dilatation of the ascending aorta (about 7.5 cm at the proximal portion) and aortic annulus, an intimal flap in the ascending aorta and aortic arch was also noted. Cardiac catheterization revealed the pulmonary capillary wedge pressure was 33 mmHg, pulmonary artery pressure was 47/38 mmHg with a mean of 35.4. The cardiac index was 1.01 l/min/m2. Poor left ventricular contractility was shown by a left ventricular ejection fraction (LVEF) of 13.8% and a right ventricular ejection fraction (RVEF) of 5.13% by a radionuclide angiogram (RNA) study. Under the diagnosis of dilated cardiomyopathy and dissecting aortic aneurysm of the ascending aorta and aortic arch, he was put on a waiting list for heart transplantation. On November 11, 1997 he received heart transplantation. Resection of the dissecting aneurysm of the ascending aorta and the aortic arch and replacement with a 26 mm Vascutek graft were performed first under deep hypothermia and retrograde cerebral perfusion. Then while he was rewarming up, heart implantation was performed. He was discharged 30 days after surgery and has been doing well since then. As far as we know, no literature regarding combined heart transplantation and resection of a dissecting aneurysm of the ascending aorta and aortic arch has been reported.

Adult↗
PubMed2000

Current status of artificial hearts and ventricular assist devices.

Currently available approaches for patients with refractory heart failure include intravenous inotropic therapy, partial left ventriculectomy, dynamic cardiomyoplasty, mechanical circulatory support, and heart transplantation. Heart transplantation is limited by the availability of donor organs, which is never expected to meet the increasing demand. Numerous devices have been developed for circulatory support. Currently available devices differ in configuration, anatomic location, flow characteristics, and durability. Many devices are currently available for mechanical support, and they can generally be categorized as follows: 1) pulsatile or continuous blood flow; 2) internal (implantable) or external (extracorporeal); 3) pneumatically or electrically powered; and 4) for short-term or long-term support. Proper selection of patients for a given therapy has a major impact on clinical outcome. Early implantation of implantable devices, before the onset of multiple or irreversible end-organ failure, is essential. Short-term devices are indicated if myocardial recovery is anticipated, as in cases of postcardiotomy shock and acute myocarditis. Long-term devices are indicated for transitioning patients with end-stage myocardial failure to heart transplantation. Long-term assist devices may, in some selected cases, serve as an alternative to heart transplantation. This alternative will benefit both patients in chronic heart failure competing for a limited donor supply and patients with contraindications to transplantation, such as advanced age, previous malignancies, and renal dysfunction. The next generation of blood pumps to be applied clinically is likely to be axial pumps, which are valveless, miniaturized, intraventricular left ventricular assist devices.

Heart, Artificial↗
PubMed2000

Partial left ventriculectomy as a biologic bridge to heart transplantation.

Heart failure refractory to medical treatment is consuming an increasingly large proportion of health care resources. Partial left ventriculectomy has recently been used to treat patients with end-stage dilated cardiomyopathy. A 45-year-old man in end-stage heart failure had progressive exertional dyspnea for 3 years. Cardiac catheterization showed dilated cardiomyopathy with severe pulmonary hypertension and severely impaired left ventricular function. After partial left ventriculectomy, cardiac output increased from 2.11 L/min to 5.0 L/min. The left ventricular ejection fraction measured by radionuclide angiography increased from 13% preoperatively to 28% 1 month after the operation. The patient was discharged and monitored at the outpatient clinic. He had an exercise capacity of NYHA functional class II. However, he received heart transplantation 10 months after the partial left ventriculectomy because of recurrent heart failure. Partial left ventriculectomy improves heart function and may be used as a bridge to heart transplantation as an alternative to ventricular assist devices.

Cardiomyopathy, Dilated↗
PubMed2000

Aorto-right artrial fistula: a rare complication of aortic dissection.

We describe the successful surgical repair of an acute aortic dissection that had caused an aorto-right atrial fistula in a 67-year-old man. The patient was admitted to the hospital on an emergency basis because of severe heart failure. The diagnosis of acute aortic dissection with rupture into the right atrium was confirmed by use of intraoperative transesophageal echocardiography, although rupture of a sinus of Valsalva aneurysm into the right atrium had been suggested initially by 2-dimensional and Doppler transthoracic echocardiography. At surgery, we found the patient to have aortic arch dissection with complete separation of the right coronary artery from the sinus of Valsalva and a false lumen that had ruptured into the right atrium. The aortic arch was repaired directly. The ascending aorta was successfully replaced with a composite graft. Aortic dissection with rupture into the right atrium is extremely rare and leads to death rapidly. As shown in this case, such a condition might be mistaken for an aneurysmal rupture of the sinus of Valsalva, with use of transthoracic echocardiography alone. Transesophageal echocardiography is a useful noninvasive method to further define or confirm the diagnosis. Early surgical intervention is necessary in patients with this condition to prevent profound shock and end-organ failure.

Aged↗
PubMed2000

HeartMate left ventricular assist device for long-term circulatory support.

We describe three successful cases of HeartMate left ventricular assist device (LVAD; Thermo Cardiosystems, Woburn, MA, USA) implantation in patients with end-stage heart failure for long-term circulatory support. Patient 1 was a 34-year-old woman with postpartum cardiomyopathy. Patients 2 and 3 were both males with dilated cardiomyopathy, 50 years and 21 years of age, respectively. They all presented in cardiogenic shock with decreased sensorium and anuria. Temporary mechanical support with an intra-aortic balloon pump or extracorporeal membrane oxygenation (ECMO) was needed for life support. Because bleeding and right ventricular failure often occur after HeartMate LVAD implantation, we used a Vascutek tube (Vascutek Ltd, Inchinnan, Scotland) graft to wrap inflow and outflow valve conduits and ECMO as a bridge to HeartMate LVAD implantation. Following surgery, cardiac output increased from 2.70, 2.06 and 2.53 L/min to 4.50, 5.80 and 5.00 L/min in the three patients. HeartMate LVAD can provide safe and stable long-term circulatory support without the need for anticoagulation. One of the patients remained on HeartMate for 287 days before undergoing successful heart transplantation. Patients with HeartMate LVAD are ambulatory and may be discharged while awaiting heart transplantation. Heart function may recover after long-term ventricular unloading with HeartMate LVAD.

Adult↗
PubMed2000

Surgical revascularization for acute total occlusion of left main coronary artery.

We report our experience with emergency surgical revascularization in 3 patients who were in cardiogenic shock as a result of acute total occlusion of the left main coronary artery. Because they were in profound shock, 2 patients required mechanical support with extracorporeal membrane oxygenation before the operation. Another patient was given moderate inotropic support and treated with an intraaortic balloon pump before surgery, because he had a dominant right coronary artery with extensive collateral circulation to the left coronary artery. All 3 patients underwent surgical revascularization within 20 hours of acute occlusion. Two patients survived, although 1 of them required extracorporeal membrane oxygenation support for 5 days postoperatively. The 3rd patient, despite successful weaning from extracorporeal membrane oxygenation immediately after coronary revascularization, died of hypoxic encephalopathy due to prolonged preoperative resuscitation. Immediate surgical revascularization was an effective treatment in our 3 patients who were in cardiogenic shock due to acute total occlusion of the left main coronary artery. Such factors as abundant collateral vessels from the right coronary artery to the left coronary artery, complete surgical revascularization within 20 hours of acute occlusion, and mechanical circulatory support were deemed important to recovery of left ventricular function. Two of our 3 patients survived.

Adult↗
PubMed2000

Ventricular remodeling of the native heart after heterotopic heart transplantation.

Although ventricular remodeling after long-term unloading of the heart has been reported in patients after the use of medical therapy or left ventricular assist devices, it has rarely been reported in patients after heterotopic heart transplantation. Here, we describe a case of ventricular remodeling of the native heart after heterotopic heart transplantation. A 61-year-old man with end-stage dilated cardiomyopathy underwent heterotopic heart transplantation because of high pulmonary vascular resistance and a small donor heart. After the operation, echocardiography showed ventricular remodeling of the native heart, with decreased size and improved contractility of the left ventricle. Six months after the transplantation, acute graft failure of the donor heart occurred. However, the patient remained in good condition with the support of the improved native heart.

Cardiomyopathy, Dilated↗
PubMed2000

The role of free to total prostate-specific antigen ratio for prostate cancer in screening patients with total serum levels between 4 and 20 ng/ml.

BACKGROUND: We retrospectively tried to determine if the free to total prostate-specific antigen (f/t PSA) ratio could improve the specificity of PSA in prostate cancer screening of patients with total serum levels between 4 and 20 ng/ml. METHODS: Two hundred ninety-five patients with serum PSA levels from 4 to 20 ng/ml had undergone sextant prostate needle biopsy. Each patient had no prior history of prostate cancer, acute urine retention, or prostatitis. Prebiopsy free PSA values were measured in 155 patients. Total PSA levels were determined with the AxSYM enzyme-linked immunosorbent assay. Free PSA levels were measured with the AxSYM microparticle enzyme immunoassay. RESULTS: Mean f/t PSA ratios were 0.114+/-0.004 in men of the cancer group and 0.161+/-0.008 in men of the benign group (p<0.002). Based on the analysis of sensitivity and specificity in relation to f/t PSA ratios, use of the 18% cutoff point could detect 89% of cancer cases, and at the same time could avoid 35% of unnecessary prostate biopsies. The areas under the receiver-of-characteristic curve for f/t PSA ratio and total PSA were 0.649 and 0.545, respectively. CONCLUSION: Serum f/t PSA ratios were significantly lower in patients with prostate cancer than in patients with benign disease. The determination of an appropriate f/t PSA ratio should be based on the generated data such as that demonstrated in this study in order to improve diagnostic accuracy and specificity for patients with equivocal PSA values and to avoid conducting unnecessary prostate biopsies.

Aged↗
PubMed1999

A patient with bilateral primary adrenal lymphoma, presenting with fever of unknown origin and achieving long-term disease-free survival after resection and chemotherapy.

Primary adrenal lymphoma is extremely rare. We describe a 64-year-old female patient who presented with fever of unknown origin. Imaging studies demonstrated bilateral bulky adrenal masses. She underwent bilateral adrenalectomy and the pathological diagnosis was large cell immunoblastic (B-cell) lymphoma. She received adjuvant combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone in the following 6 months. She has been relapse free for 52 months. To the best of our knowledge, this case has the longest disease-free survival among those reported. The present case indicated that primary adrenal lymphoma should be included in the differential diagnosis of fever of unknown origin and/or suprarenal mass. Chemotherapy following surgical resection may be considered the treatment of choice.

Adrenal Cortex↗
PubMed1999

Rescue for acute myocarditis with shock by extracorporeal membrane oxygenation.

BACKGROUND: Acute myocarditis (AM) complicated with refractory cardiogenic shock carries a very high mortality. We report our experience in treating these patients, who were rescued by extracorporeal membrane oxygenation (ECMO) and intravenous immunoglobulin. METHODS: Over a 5-year period, 5 patients with AM were rescued with ECMO in our hospital. Femoral venoarterial ECMO was performed in 4 patients, and right atrium-left atrium-aorta ECMO in the other 1 due to ventricular dysfunction. Hemofiltration was applied to 3 patients. Marked elevated creatine kinase, its MB form, and troponin T (TnT) were found before ECMO. RESULTS: All the patients could be weaned off the ECMO after 140.0+/-57.7 hours of ECMO support. One patient died of multiple organ failure 10 days later after removal of ECMO, resulting in a 20% mortality. Renal function returned to normal in all survivors. The 4 survivors were discharged uneventfully in 23.3+/-8.3 days and resumed functional class I status. The TnT level declined to the low level within 3 days (slope -4.94+/-1.18 ng/mL/day), and might be an indicator of good recovery of myocardium. CONCLUSIONS: ECMO can provide an effective and simple treatment for critical AM with a satisfactory result and reduce the possibility of progressive cardiomyopathy.

Acute Disease↗
PubMed1999

Low incidence of transplant coronary artery disease in Chinese heart recipients.

OBJECTIVES: This study sought to assess the incidence of transplant coronary artery disease (CAD) in Chinese heart recipients. BACKGROUND: The prevalence of transplant CAD detected by angiography at 1, 2 and 4 years after heart transplantation was 11%, 22% and 45%, respectively. The incidence of transplant CAD in Chinese heart recipients has not been reported. METHODS: For those recipients surviving for more than 1 year after transplantation, coronary angiography was performed annually for surveillance of transplant CAD. The recipient characteristics, donor characteristics, rejection episodes, medication and human leukocyte antigen (HLA) mismatches were recorded. RESULTS: Fifty patients were included in this study. Thirteen (26%) recipients had ischemic heart disease. Two patients (4%) had active cytomegalovirus (CMV) infection after transplantation. The mean number of rejection episodes in the 1st year after transplantation was 1.15. Among 47 patients with complete data of donor and recipient histocompatibility antigens, there were seven patients (14.9%) with two or fewer HLA mismatches. Among 74 angiograms of 50 patients reviewed, only one patient had discrete stenosis less than 50% in the middle portion of the left anterior descending artery at 1 year after transplantation. The cumulative incidence of transplant CAD was 2% at 1 year and 2% at 2 and 4 years after transplantation. CONCLUSIONS: The incidence of transplant CAD was low in Chinese heart transplant recipients. Low percentage of ischemic heart disease in recipients, low occurrence of active CMV infection and rejection episodes after transplantation, less racial disparity, and lower HLA mismatches may be the important factors.

Adolescent↗
PubMed1999

Lung transplantation for patients with end-stage Sauropus androgynus-induced bronchiolitis obliterans (SABO) syndrome.

Sauropus androgymus (SA), a vegetable of the Euphorbiaceae family, is a common food source in Malaysia. In Taiwan, over 30 patients have developed progressive respiratory failure after consuming the extract from raw SA leaves as a means of losing weight. Symptoms consistent with a severe obstructive ventilatory defect progressed, despite cessation of SA intake and treatment with bronchodilators, corticosteroids, cytotoxic agents and plasmaphresis. Five patients with end-stage Sauropus androgynus-induced bronchiolitis obliterans (SABO) syndrome underwent lung transplantation. There was no early mortality. One patient died of post-transplant lymphoproliferative disorder and another patient died of bronchial stenosis with infection, 5 and 3.5 months, respectively, post-transplantation. The remaining 3 patients have been followed from 29 to 34 months, with improved general condition and pulmonary function. Perfusion/ventilation scans revealed that these improvements were exclusively attributed to the functional grafts. We believe that lung transplantation is the only effective modality of treatment for patients with end-stage SABO syndrome.

Adult↗
PubMed1999

Unpreconditioned free revascularized dynamic cardiomyoplasty. Is it feasible?

BACKGROUND: Cardiomyoplasty is a new ventricular bioassist device for myocardial failure. But there are some limitations in standard cardiomyoplasty, such as the orientation of the muscle and fiber and the efficiency of the contractile segment of the flap. Free revascularized latissimus dorsi flap may be a good idea for solving these problems. METHODS: We designed a canine free latissimus dorsi flap by revascularizing the flap with the left internal thoracic vessels by micro-surgical technique. Group I (n = 3) as control was performed by standard cardiomyoplasty, and the Group II (n = 10) was performed by the revascularized method. The heart was then wrapped by the revacularized flap. Group II was divided into IIa (n = 6, no pre-treatment before revascularization) and IIb (n = 4, normal saline pre-treatment before revascularization) by the different preservation methods. Hemodynamic data were recorded. RESULTS: Group I all survived the 8-week training period. But Group II, Group IIa and IIb, all died in 3 days, but survived more than 12 hours. The hemodynamic analysis in Group I did not show any significant change except left ventricular end diastolic pressure. It showed elevated left ventricular pressure when the cardiostimulator was ON. CONCLUSIONS: According to the result of this experiment, it seemed impossible to get a satisfactory result of more than 3 days for free revascularized cardiomyoplasty at present. There were a lot of problems waiting to be solved, such as preservation method during ischemia, bulky mass of the flap, and the potential problem of neuromuscular atrophy.

Anastomosis, Surgical↗