Yasunori Cho

Surgical management of isolated congenital tricuspid regurgitation

BACKGROUND Isolated congenital tricuspid regurgitation without downward displacement of the leaflet is a rare clinical entity. Degenerative cusps and lack of chordae may preclude valvuloplasty and require valve replacement. METHODS Three consecutive patients with isolated congenital tricuspid regurgitation underwent surgical repair between May 1995 and April 1997. Their ages were 23, 15, and 8 years old. Tricuspid valvuloplasty was feasible in all of them, with use of a gathering suture of the anterior leaflet, artificial chordae implantation, and ring annuloplasty. RESULTS All 3 patients survived and recovered well after the operation. The cardiothoracic ratios on their chest roentgenograms decreased from 0.64 to 0.52 in patient 1, from 0.58 to 0.48 in patient 2, and from 0.60 to 0.44 in patient 3. Postoperative echocardiograms showed competent tricuspid valves and the disappearance of regurgitation in all cases. CONCLUSIONS Although malformation of the valve is extensive in isolated congenital tricuspid regurgitation, application of artificial chordae with conventional valvuloplasty technique can avoid the use of prosthetic valves by establishing the competence of the tricuspid valve.

Feasibility and suitability of the routine use of bilateral internal thoracic arteries

BACKGROUND It has been demonstrated that bilateral use of internal thoracic arteries (ITAs) confers better long-term results in patients than does unilateral use. However, routine use of bilateral ITAs has usually been avoided. METHODS Since 1997, we have used bilateral ITAs extensively for patients who required multivessel bypasses. Recently, 243 consecutive patients, including 127 diabetic patients, were reviewed. RESULTS Every patient received at least one ITA graft, and 200 patients (82%) received bilateral ITAs. The majority (93%) of ITA grafts were used as in situ grafts. The hospital mortality rate was 0.41%, and deep sternal infections were observed in 5 patients (2.0%). There was no difference in the incidence of chest wound infection between the group treated with bilateral ITA grafting and that treated by unilateral ITA grafting. CONCLUSIONS These observations suggest that ITAs can be used bilaterally for treatment in the majority of patients who require multivessel bypass, with low mortality and morbidity.

Mitral valve replacement in patients younger than 6 years of age

UNLABELLED We present our experience in mitral valve replacement (including left-sided tricuspid valve in corrected transposition) in patients younger than 6 years of age. The long term results were examined with special focus on re-replacement of the valve. Between 1974 and 1995, we performed mitral valve replacement in 14 patients younger than 6 years of age, with no operative mortality. There were 3 late deaths, caused by endocarditis, valve thrombosis, and congestive heart failure, respectively. The five-year-survival rate after primary replacement was 85%, and the ten-year-survival rate was 75%, using Kaplan-Meier analysis. Ten patients (11 occasions) required repeated mitral valve replacements at 2 months to 17 years after the original replacement. The indication for the second or third mitral valve replacement was paravalvular leakage (2 patients), valve thrombosis (1 patient), degeneration in the porcine prosthesis (3 patients), and patient outgrowth of the original small prosthesis (5 patients). Again there was no operative mortality. One patient who suffered from multiple occasions of valve thrombosis died at two years after the second replacement. All patients who had outgrown the prosthetic valve received larger prosthesis at the second replacement than at the primary replacement. The actuarial percentage of freedom from valve-related events at 3 years, 5 years, and at 10 years, was 50%, 37%, and 8%, respectively. CONCLUSIONS Mitral valve replacement in patients younger than 6 years of age can be performed relatively safely, but meticulous follow-up and appropriate decision making for re-replacement is mandatory for the long-term survival of these patients.

Acute Aortic Dissection Involving an Aberrant Right Subclavian Artery

Although the aberrant right subclavian artery is the most common abnormality in aortic arch development, it is unusual to encounter this abnormality when repairing acute aortic dissection. We report a case of Stanford type A acute aortic dissection involving an aberrant right subclavian artery in a 45-year-old man. We used the elephant trunk procedure to surgically manage the intimal tear and aberrant right subclavian artery. This is, to our knowledge, the first report in Japan of surgical reconstruction of an aberrant right subclavian artery in conjunction with acute aortic dissection.

Video-assisted thoracoscopy system guidance in linear radiofrequency ablation.

Abstract The transcatheter creation of linear endocardial lesions in the atria has been attempted to restore sinus rhythm in patients with atrial fibrillation (AF). However, due to fluoroscopic limitations, there are a number of technical difficulties involved with using this procedure, which include determining the ablation site, orienting the catheter tip, and confirming tip-tissue contact. The present study was performed to assess the feasibility of employing a transthoracic approach to linear radiofrequency ablation using a video-assisted thoracoscopy system (VATS) to anatomically guide the experimental setting in beating swine hearts. AF was induced pharmacologically by aconitine solution. Epicardial radiofrequency linear ablation of the right atrium was conducted under VATS monitoring using an ablation catheter that was inserted and manipulated through trocar ports. The ablation energy setting was 80°C with 30 s duration per ablation. The thoracoscopic visual field for transthoracic ablation was adequate, and the ablation catheter was positioned and anchored safely on the atrial epicardium. The restoration of sinus rhythm was confirmed in the limb lead and atrial electrograms, and transmural heat degeneration was confirmed by postmortem histological examination in all specimens. Our results suggest the potential usefulness of VATS for providing adequate anatomical guidance in epicardial linear radiofrequency ablation.

Exogenous aspartate neurotoxicity in the spinal cord under metabolic stress in vivo.

BACKGROUND Considerable evidence exists that neurotoxicity of excitatory amino acids is related to the neuronal injury, including paraplegia. However, little is known about aspartate neurotoxicity in the spinal cord in vivo. We evaluated the detrimental effects of exogenous aspartate on spinal cord neurons under metabolic stress. METHODS New Zealand white rabbits underwent an infrarenal aortic isolation. Group A animals (n = 7) received segmental aspartate 50 mmol/L) infusion for 10 minutes. Group B animals (n = 7) received saline as a negative control. Group C animals (n = 5) received segmental aspartate 100 mmol/L) infusion for 5 minutes. Group D animals (n = 7) were pretreated with segmental infusion of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cycloheptan-5,10-imine (MK-801) (6 mg/kg), a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist for 1 minute, followed by segmental infusion of aspartate (50 mmol/L) for 9 minutes. Group E animals (n = 7) received vehicle only, followed by aspartate (50 mmol/L) infusion as a control of group D. Neurologic status was assessed at 12, 24, and 48 hours after operation using the Tarlov score. RESULTS Group A animals exhibited paraplegia or paraparesis with marked neuronal necrosis. Group B and C animals recovered fully. Group D animals showed significantly better neurologic function (p = 0.0007) compared with group E animals that exhibited paraplegia or paraparesis. CONCLUSIONS Exogenous aspartate can have detrimental effects on spinal cord neurons under metabolic stress. This model may be useful in assaying neuronal injury mediated by NMDA receptor in vivo.

The proliferative potential of human cardiac stem cells was unaffected after a long-term cryopreservation of tissue blocks

Hepatocellular carcinoma (HCC) is the sixth most common worldwide cancer and has dismal outcomes because of its high morbidity and mortality, particularly in Eastern countries (1,2); however, the morbidity of HCC is increasing in the Western counties (3). Portal vein tumor thrombosis (PVTT) occurs in 44–62.2% of patients with advanced HCC a with a natural median survival time (MST) of 2.7–4 months and is the most commonly recognized risk factor for prognosis (4). PVTT is regarded as an advanced stage of HCC, and sorafenib is only recommended to treat PVTT according to the American Association for the Study of the Liver Disease/Barcelona Clinic Liver Cancer (AASLD/BCLC) staging system and treatment guidelines (5-7). Despite recent advances in the treatment of such patients, the treatment strategies for PVTT remain controversial.

Surgical treatment of an interatrial septal paraganglioma

A 39-year-old man presented with chest pain. Chest radiography and echocardiography indicated a possible cardiac tumor. Echocardiography, computed tomography, and magnetic resonance imaging revealed a tumor in the interatrial septum. The patient underwent tumor resection under cardiopulmonary bypass. A paraganglioma was diagnosed on the basis of histopathological findings.

Current density distribution by ring and diagonally arranged half-ring electrodes in bipolar and overlapping biphasic impulse stimulation.

Background:  We have studied the acute and long‐term efficacy of overlapping biphasic impulse (OLBI) stimulation for atrial pacing with VDD pacemakers and demonstrated the feasibility of DDD pacing in OLBI with diagonally arranged half‐ring (Half‐Ring) electrodes. We made two three‐dimensional computational analysis models to verify our clinical studies.

The role of bidirectional cavopulmonary shunt on selection of Fontan patients

There are no objection against that pulmonary vascular resistance index (PVRI) is one of the most important factors for completion of successful application of Fontan-type operation. However, calculated PVRI in single ventricle physiology in often unreliable because of difficulty in accurate measurement of pulmonary blood flow, especially in patients with decreased pulmonary blood flow. Although the role of bidirectional cavopulmonary shunt (BCPS) in such patients has been increasingly recognized, the impact of BCPS on PVRI has not been fully understood. Between November 1993 and November 1996, 24 patients, aged between 0.54 and 22.2 years, with a wide variety of cardiac malformations underwent BCPS, and were followed up for the mean of 15.1 months. There were four hospital deaths (16.7%) and three deaths in follow-up (12.5%). Serial catheterization revealed that significant increase in mean arterial oxygen saturation from 75.8% to 83.9% (p = 0.005), and decrease in mean Nakatas index from 433 to 311 (p < 0.0001). PVRI calculated by using formulas derived from Ohms law before BCPS (Pulmonary flow was derived from Fick formula) was highly (greater than 10 u.m2) or moderately (between 4 and 10 u.m2) elevated in 6 and 7 patients, respectively. However, PVRI in these patients was normal after BCPS. Fourteen out of 24 patients underwent total cavopulmonary connection (TCPC) with 8 to 15 months of interval from BCPS, and have been currently surviving, and in NYHA functional class I or II, except 2 patients who underwent take-down. In conclusion, early and midterm outcome after staged operation appears to be excellent. BCPS is a good interim procedure, in part because one can more properly select patients undergoing Fontan operations from the PVRI point of view.