Toshihiko Saga

Natural killer cells recognize Friend retrovirus-infected erythroid progenitor cells through NKG2D-RAE-1 interactions in vivo

ABSTRACT Natural killer (NK) cells function as early effector cells in the innate immune defense against viral infections and also participate in the regulation of normal and malignant hematopoiesis. NK cell activities have been associated with early clearance of viremia in experimental simian immunodeficiency virus and clinical human immunodeficiency virus type 1 (HIV-1) infections. We have previously shown that NK cells function as major cytotoxic effector cells in vaccine-induced immune protection against Friend virus (FV)-induced leukemia, and NK cell depletion totally abrogates the above protective immunity. However, how NK cells recognize retrovirus-infected cells remains largely unclear. The present study demonstrates a correlation between the expression of the products of retinoic acid early transcript-1 (RAE-1) genes in target cells and their susceptibility to killing by NK cells isolated from FV-infected animals. This killing was abrogated by antibodies blocking the NKG2D receptor in vitro. Further, the expression of RAE-1 proteins on erythroblast surfaces increased early after FV inoculation, and administration of an RAE-1-blocking antibody resulted in increased spleen infectious centers and exaggerated pathology, indicating that FV-infected erythroid cells are recognized by NK cells mainly through the NKG2D–RAE-1 interactions in vivo. Enhanced retroviral replication due to host gene-targeting resulted in markedly increased RAE-1 expression in the absence of massive erythroid cell proliferation, indicating a direct role of retroviral replication in RAE-1 upregulation.

Antegrade selective cerebral perfusion with mild hypothermic systemic circulatory arrest during thoracic aortic surgery

Objective Antegrade selective cerebral perfusion (ASCP) and retrograde cerebral perfusion (RCP) have proven to be reliable methods of brain protection during aortic surgery. These techniques are usually accompanied by systemic circulatory arrest with moderate hypothermia (24–28°C) or deep hypothermia (18–24°C). However, hypothermia can lead to various problems. The present study therefore reports results for thoracic aorta replacement using ASCP with mild hypothermic systemic arrest (28–32°C). Design Between 1995 and 2003, 68 consecutive patients underwent repair of the ascending aorta and/or aortic arch. Mild hypothermic ASCP was utilized in 31 cases, moderate hypothermic ASCP in 20, and deep hypothermic RCP in 17. Various parameters were compared between the mild hypothermic ASCP, moderate hypothermic ASCP, and RCP. Results Hospital mortality was 10.3%, with no significant differences observed between any groups. Permanent neurological dysfunction was 8.8%, and no significant differences were observed between any groups. Mild hypothermic ASCP displayed significantly decreased transfusion volume, intubation time, and ICU stay. Conclusions Use of ASCP with mild hypothermic systemic circulatory arrest during aortic surgery resulted in acceptable hospital mortality and neurological outcomes. ASCP with mild hypothermic arrest allows decreased transfusion volume and reduced duration of intubation and ICU stay.

Bivalvation with bridging for common atrioventricular valve regurgitation in right isomerism

A child with regurgitation in the common atrioventricular valve associated with complex heart disease underwent bivalvation with bridging for common atrioventricular valve regurgitation and arterial-pulmonary shunt for low pulmonary blood flow. Postoperative cardiac catheterization and color Doppler echocardiography revealed elimination of atrioventricular valve regurgitation and ventricular enlargement, reflecting an increase in pulmonary artery blood flow. We describe the concept and technique of bivalvation with bridging for common atrioventricular valve regurgitation.

Semilunar Valve Replacement with a Cylindrical Valve

Abstract A cylindrical valve was designed to prevent regurgitation of the semilunar valve. The valve is made of a sheet of polytetrafluoroethylene (PTFE) or porcine pericardium, and has three cusps and three commissures. The diameter of the valve is equal to the height of the cusps. We have used these valves in pulmonary stenosis after Jatenes operation and total correction of tetralogy of Fallot, and for truncal valve regurgitation. Regurgitation was trivial on color Doppler echocardiography in all cases. Advantages in comparison with the implantation of commercially available artificial valves include the ability to insert a larger size and no compression of the valve ring when closing the sternum. Outflow tract obstruction does not occur even when the valve is implanted in a small infant. In the present report, we describe this simple technique.

Williams syndrome associated with complete atrioventricular septal defect

Williams syndrome is a genetic disorder associated with characteristic facies, supravalvar aortic stenosis, peripheral pulmonary stenosis, mental retardation, hypertension, premature aging of skin, and congenital cardiac defects. Many cardiac defects such as bicuspid aortic valve, mitral valve regurgitation, coarctation of the aorta, and ventricular or atrial septal defects are linked to the syndrome. Complete atrioventricular septal defect has rarely been associated with Williams syndrome and only one necropsy case has been reported in the literature. The long term follow up of Williams syndrome associated with complete atrioventricular septal defect is reported. During a 10 year follow up period, the pressure gradient in the ascending aorta did not increase despite narrowing of the ascending aorta as identified on an aortogram.

Congestive heart failure due to coral reef thoracoabdominal aorta

Acquired coarctation due to coral reefs is a rare and unique entity characterized by extensively calcified thrombus of the entire aorta. There are few reports of coral reef aorta resulting in severely congestive heart failure in the literature. We describe a 60-year-old female with acute heart failure. Computed tomography (CT)-scan and magnetic resonance imaging (MRI) revealed that the cause of the heart failure was cardiac after-load mismatch due to serious stenosis of the aorta. In order to prevent cardio-respiratory failure, an axillofemoral bypass was performed to release the cardiac after-load mismatch. This diminished the pressure gradient between upper and lower blood pressure that caused cardiac dysfunction.

Five-Year Clinical Outcome of Asymptomatic vs. Symptomatic Severe Aortic Stenosis After Aortic Valve Replacement

BACKGROUND There is discordance regarding the effect of symptom status before aortic valve replacement (AVR) on long-term outcome after AVR in severe aortic stenosis (AS).Methods and Results:The CURRENT AS registry is a multicenter retrospective registry enrolling 3,815 consecutive patients with severe AS. Among 1,196 patients managed with the initial AVR strategy, long-term clinical outcomes were compared between the symptomatic patients (n=905), and asymptomatic patients (n=291). Median follow-up interval was 1337 days with a 91% follow-up rate at 2 years. AVR was performed in 886 patients (98%) in the symptomatic group and in 287 patients (99%) in the asymptomatic group. Symptomatic patients were older and more often had comorbidities than asymptomatic patients with similar echocardiographic AS severity. The cumulative 5-year incidences of all-cause death and heart failure (HF) hospitalization were significantly higher in symptomatic patients than in asymptomatic patients (25.6% vs. 15.4%, P=0.001, and 14.2% vs. 3.8%, P<0.001, respectively). On landmark analysis at 30 days after AVR, the differences in mortality and HF hospitalization between the 2 groups were mainly observed beyond 30 days. CONCLUSIONS When managed with the initial AVR strategy, the long-term outcomes of symptomatic severe AS were worse than those of asymptomatic severe AS. Early AVR strategy might be recommended in some selected asymptomatic severe AS patients with reasonable operative risk.

Intravascular Extraction of Permanent Pacemaker Leads

Abstract.Purpose: Cardiac leads that became infected, fail, or are otherwise problematic present difficulties in the management of patients. In this report, we assess our intravascular countertraction technique. Method: Between February 1990 and January 2001, 13 leads were removed from 11 patients using the intravascular countertraction technique. The reasons for lead extraction were pacemaker infection and lead dysfunction. Results: In two of these patients, the ventricular leads could not be completely removed. The complete success rate was 85% and the overall success rate was 92%. There were no serious complications such as cardiac rupture, vein injury, or death, and there were no clinical signs of pulmonary embolism. In one of the patients whose ventricular leads could not be removed completely, the ventricular lead was stretched from its previous round shape, but tricuspid valve regurgitation did not occur during the 3-year follow-up period. In the other patient, the distal electrode was left in the subclavian vein. However, this residual distal electrode did not migrate, and there were no clinical signs of any recurrence of infection. Conclusions: The present study suggests that to remove leads successfully, the largest locking stylet that can be easily passed to the leads tip through the coil lumen should be chosen in order to avoid valve injury, which can sometimes occur when a ventricular leads locking stylet is left in the coil lumen.

Total extracardiac right heart bypass using a polytetrafluoroethylene graft.

Abstract Background: With regard to hemodynamics and late arrhythmias, total cavopulmonary connection has been accepted as a superior technique as compared to Fontan type procedures. However, intra‐atrial baffles for lateral tunnel or conduit remain construction retain some similar disadvantages. Patients and Methods: As an alternative to total cavopulmonary connection, total extracardiac right heart bypass using a polytetrafluoroethylene tube for the inferior vena cava to pulmonary artery connection may obviate some problems. Five patients with complex heart disease necessitating one ventricle repair underwent this procedure successfully. Results: Aortic cross‐clamp time ranged from 0 to 24 minutes (mean = 15.8 min). No case required takedown or an additional step. Although the follow‐up periods have been relatively short (mean = 19 months), all patients are well and no arrhythmic event or thromboembolic episode has occurred. Conclusions: As a simple, safe, and reproducible procedure, total extracardiac right heart bypass is an alternative to Fontan or total cavopulmonary connection procedure.

Renal Preservation in Low Ectopic Right Renal Artery Reconstruction During Abdominal Aortic Aneurysm Repair: Report of a Case

Abstract.Renal hypothermia achieved using cold (4°C) heparinized Ringers lactate is an effective method of preventing renal compromise during abdominal aortic surgery. We present the case of a 62-year-old man with an abdominal aortic aneurysm (AAA), complicated by involvement of an ectopic right renal artery with a low abdominal aortic origin and passage across the ventral side of the inferior vena cava. The patient underwent AAA repair and right renal artery reconstruction using renal perfusion with cold heparinized Ringers lactate, and no deterioration of renal function occurred.