Koh Takeuchi

Surgical outcome of double-outlet right ventricle with subpulmonary VSD

BACKGROUNDnOptimal management of double-outlet right ventricle with subpulmonary ventricular septal defect remains controversial. We reviewed our 7-year experience with patients who had this anatomic configuration.nnnMETHODSnBetween January 1992 and January 1999, 20 patients underwent an arterial switch operation (ASO group), and 12 underwent a bidirectional Glenn procedure followed by a modified Fontan in 10 (Glenn/Fontan). Mean follow-up was 23 +/- 18 months.nnnRESULTSnAn initial palliative operation was done in 19 patients (9 in the ASO group, 10 in the Glenn/Fontan group). There were no deaths in the Glenn/Fontan group. Four patients in the ASO group died within 33 days postoperatively. Two of them had a single coronary artery, 1 had a straddling mitral valve, 1 had a hypoplastic aortic arch, and 1 had multiple ventricular septal defects. Three patients had reoperation for subaortic stenosis (n = 2) or pulmonary stenosis (n = 1) after the ASO. Four patients (3 in the ASO group, 1 in the Glenn/Fontan) required a pacemaker for postoperative complete atrioventricular block. Actuarial survival at 5 years for the entire group was 87% (70% confidence interval, 81% to 93%).nnnCONCLUSIONSnThe ASO remains our preferred treatment for infants with double-outlet right ventricle and subpulmonary ventricular septal defect. However, associated anatomic defects are important risk factors.

Improved Protection of the Hypertrophied Left Ventricle by Histidine-Containing Cardioplegia

BACKGROUNDnMyocardial hypertrophy has been shown to lead to increased susceptibility to ischemia with accelerated loss of high-energy nucleotides, greater accumulation of H+ and lactate, and earlier onset of contracture.nnnMETHODS AND RESULTSnTo determine whether promoting anaerobic glycolysis during ischemia by buffering H+ results in improved preservation of the hypertrophied heart, we studied the effect of a histidine-containing solution (HBS) on recovery of contractile function and energetic state. Hypertrophied rabbit hearts (aortic banding at 10 days) were subjected to 40 minutes of 37 degrees C ischemia and reperfusion in an isolated Langendorff model. This group was compared with groups receiving St Thomas solution and high-potassium Krebs buffer solution (KCl). Although both phosphocreatine (PCr) and ATP were lower in hypertrophied hearts by end-ischemia compared with nonhypertrophied age-matched controls, there was significantly higher PCr, ATP, and intracellular pH in the HBS group compared with the St Thomas and KCl groups. Recovery of left ventricular developed pressure was best in the HBS group (91% of preischemic values) as was end-diastolic pressure after 30 minutes of reperfusion. Lactate production was also significantly greater in the HBS group, suggesting augmentation of anaerobic glycolysis.nnnCONCLUSIONSnWe concluded that administration of histidine-containing cardioplegia promotes anaerobic glycolysis and improves recovery of high-energy phosphates and contractile function in hypertrophied myocardium.

Increased myocardial calcium cycling and reduced myofilament calcium sensitivity in early endotoxemia

BACKGROUNDnMechanisms of cardiac dysfunction during endotoxemia are multiple and their targets uncertain. This study tested the hypothesis that endotoxin (LPS) induces abnormal calcium-activated contractile force in the heart.nnnMETHODSnAdult rabbits were given LPS intravenously; 2 hours later hearts were studied in the Langendorff mode. Measurements included peak developed pressure (PDP), myocardial oxygen consumption (MVO2), high-energy phosphates by 31P-NMR, and beat-to-beat intracellular calcium (Cai) by fluorescence spectroscopy. Myofibrillar calcium sensitivity was assessed from the relationship of PDP to Cai and the rate of diastolic Cai removal (tau Ca) was quantified.nnnRESULTSnForce-calcium relationships were markedly depressed in LPS hearts despite increased Cai. MVO2 was increased in parallel with increased Cai. Taken together, these data denote myofilament calcium insensitivity and mechanical inefficiency. tau Ca was markedly prolonged in LPS hearts, indicating impaired calcium reuptake and/or extrusion. High-energy phosphates and intracellular pH were unaffected by LPS; however, inorganic phosphate (Pi) was significantly increased. Dobutamine further increased Cai and MVO2 in LPS hearts without significantly improving calcium-activated force. Pyruvate, an inotrope that reduces Pi, significantly improved contractility in LPS hearts.nnnCONCLUSIONSnEndotoxemia rapidly induced futile calcium cycling and reduced myofibrillar calcium sensitivity. This state was resistant to beta-agonist inotropic stimulation; inotropes that normalize the calcium-force relationship may be more effective.

Myocyte apoptosis occurs early during the development of pressure-overload hypertrophy in infant myocardium.

OBJECTIVEnAbnormal hemodynamic loading often accompanies congenital heart disease both before and after surgical repair. Adaptive and maladaptive myocardial responses to increased load are numerous. This study examined the hypothesis that myocyte loss occurs during compensatory hypertrophic growth in the developing infant myocardium subjected to progressive pressure overload.nnnMETHODSnPressure-overload left ventricular hypertrophy was induced in 7- to 10-day-old rabbits by banding the thoracic aorta. Left ventricular function and mechanics were quantified by serial echocardiography and noninvasive left ventricular wall stress analysis. Left ventricular tissue sections were examined for fibrosis by using Massons trichrome stain and for myocyte apoptosis by using a myocyte-specific DNA fragmentation assay and caspase-3 activation (specific fluorescent substrate).nnnRESULTSnSignificant myocyte apoptosis (198 +/- 37/10(6) myocytes, P < .01 vs control) and caspase-3 activation were present in early hypertrophy when left ventricular contractility was preserved and compensatory hypertrophy had normalized wall stress. By 6 weeks, multiple indices of left ventricular contractility were reduced, and left ventricular wall stress was increased. Myocyte apoptosis was accelerated (361 +/- 56/10(6) myocytes), caspase-3 activity further increased, and the estimated total number of left ventricular myocytes was significantly reduced by 18% +/- 4%.nnnCONCLUSIONnIn experimental infant left ventricular hypertrophy, myocyte apoptosis is initiated in the face of normalized wall stress and preserved contractility. The ongoing rate of apoptosis causes a measurable decrease in myocyte number that is coincident with the onset of ventricular dysfunction. It thus appears that pressure overload, even at its earliest stages, is not well tolerated by the developing ventricle.

A prostacyclin analogue reduces free radical generation in heart-lung transplantation

The mechanism by which prostacyclin acts to prevent in vivo reperfusion injury is still uncertain. This study was therefore undertaken to assess the effect of a stable prostacyclin analogue (OP 41483-alpha-CD [OP]) on oxygen-derived free radicals after heart-lung transplantation. OP was administered to the heart-lung graft through the pulmonary artery for 25 minutes encompassing the reperfusion process. Free radicals were directly measured by electron spin resonance spectroscopy. The radical intensities of pulmonary venous blood were significantly lower in the OP group than in the control group, suggesting that fewer free radicals were generated in the lungs of the OP group. The cardiac and respiratory function were better in the OP group than in the control group. The lung is the primary source of oxygen free radical attack, and the beneficial action of OP on free radical generation is almost exclusively restricted to the lung and does not apply to the heart. This result suggested that OP probably is effective in inhibiting free radical generation from the endothelium.

Restoration of sarcoplasmic reticulum protein level by thyroid hormone contributes to partial improvement of myocardial function, but not to glucose metabolism in an early failing heart

OBJECTIVEnIn heart failure, sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2) activity is decreased, resulting in abnormal Ca(2+) handling and contractile dysfunction. We have previously reported that impaired glucose transporter (GLUT4) activity was an early indicator of progression of heart failure in pressure overload hypertrophied heart. This study was aimed to examine the contribution of both SERCA2 and glucose metabolism in pressure overload hypertrophied heart. Thyroid hormone, which is known to restore GLUT4 and/or SERCA2 function, was also tested.nnnMETHODSnHypertrophied rat heart was created by abdominal aortic banding for 16 and 26 weeks. Then 20-40 microg/kg of 3,5,3-triiodo-L-thyronine (T3) was administered subcutaneously daily for the last 4 weeks. Hypertrophied myocytes were created by the stimulation of H9c2(2-1) rat heart myoblasts with 2 micromol/L of isoproterenol for 3, 7 and 10 days. Left ventricle function of the hypertrophied rat hearts were measured in Langendorff perfusion. Myocardial protein levels of GLUT4 and SERCA2 in two models were analyzed by Western immunoblotting. Glucose and lactate concentration of cultured medium of myocytes were measured enzymatically to determine the efficacy of glycolysis.nnnRESULTSnDiastolic function (tau) was significantly deteriorated in 16-week heart with significantly lower SERCA2 protein (89.3%) than control. In 26-week heart, both systolic and diastolic function (+dP/dt max, -dP/dt max and tau) was significantly deteriorated. This was associated with significant decrease in both GLUT4 and SERCA2 protein (84.8 and 91.6%, respectively). In cultured hypertrophied myocytes, glycolysis was shifted from aerobic to anaerobic during progression of hypertrophy. GLUT4 protein was significantly decreased at day 7 (45.6% of control). This led to a down-regulation of SERCA2 protein at day 10 (51.8% of control). Although there was no impact of T3 treatment on GLUT4, SERCA2 protein level was almost reversed with partial improvement of myocardial function.nnnCONCLUSIONSnWe conclude that impairment of both glucose metabolism and SERCA2 function were seen in an early heart failure. Thyroid hormone partially improved myocardial function with successful improvement of SERCA2 protein but no impact on GLUT4 protein expression in hypertrophied rat heart. Restoration of glucose metabolism is a critical step to avoid further progression of heart failure.

Neonatal repair of right interrupted aortic arch with cerebro-myocardial perfusion technique

Right interrupted aortic arch and descending aorta is exceedingly rare and most likely cause respiratory presentation, since patent ductus arteriosus (PDA) courses over the right mainstem bronchus. We report a case of successful neonatal biventricular repair of a right interrupted aortic arch (type B), with an aberrant right subclavian artery ventricular septal defect (VSD) in a 2.7xa0kg term neonate with DiGeorge syndrome. Patient presented in severe respiratory distress and acidosis at one day old. Two-dimensional (2D) echocardiography revealed aortic arch interruption beyond the common carotid arteries with large perimembranous outlet VSD. Aortic annulus diameter was 4.8xa0mm and there was no left ventricle (LV) outflow tract obstruction. Three-dimensional (3D) CT-scan confirmed these findings and identified a right-sided ductal arch that continued over the right mainstem bronchus into a right-sided descending aorta and aberrant right subclavian artery. Brachiocephalic perfusion and ductal perfusion was employed for cooling during cardiopulmonary bypass. Under deep hypothermia (27 °C rectal temperature), selective cerebro-myocardial perfusion was used for successful aortic arch repair without sacrificing the aberrant right subclavian artery. A direct tension-free anastomosis was attained. Her postoperative course was uneventful and her respiratory symptoms disappeared postoperatively. Early surgical correction is mandatory for these patients with unique anatomy and presentation.

Current treatment options for the management of patent ductus arteriosus

Pharmacological and/or surgical closure of a hemodynamically significant patent ductus arteriosus (PDA) in the very premature infant has been the standard of care over the past few decades. However, the rationale for closure of PDA has recently been challenged. In this article, three ways of approaching the closure of PDA including pharmacological treatment, catheter intervention, and surgical intervention, are reviewed in detail. In addition, the different treatment strategies applied in clinical care are evaluated with a focus on the discussion of the available evidence of PDA treatment in the literature.

Left mammary artery bypass grafting rescued a patient with hypoplastic left heart syndrome with ascending aorta obstruction after norwood stage I procedure.

A three-month-old boy with hypoplastic left heart syndrome (mitral atresia, aortic atresia) and moderate tricuspid regurgitation developed ascending aorta obstruction two months after a Norwood stage I procedure. An emergent left mammary artery bypass grafting to the ascending aorta and extracorporeal membrane oxygenator support resulted in successful salvage. The patient subsequently underwent a bidirectional Glenn procedure and tricuspid valve repair at the age of five months. Follow-up at an outpatient clinic reveals no electrocardiographic evidence of ischemia, and echocardiography shows recovery of ventricular function.

A Case Report of Double Aortic Arch, Vascular Ring Associated with Tracheal Stenosis.

重複大動脈弓,血管輪は先天性動脈奇形では比較的希な疾患であるが心内奇形を合併しない限り,循環動態に影響を及ぼすことはなくその予後は良好である.しかしながら初発症状が喘鳴,嚥下困難といった呼吸器や消化器症状であるため確定診断にいたるまで時間を要し予期せぬ合併症に見舞われることがある.われわれは喘鳴を初発症状としたEdwards IA型の血管輪を経験した.血管輪離断術を行ったが呼吸状態の改善を認めず,2回目の手術にて動脈管索離断術およびaortopexyを施行し,人工呼吸器より離脱できた.大動脈弓離断により,気管外からの圧迫は解除されたが気管チューブの刺激による気管内壁の肥厚が原因となって,気管内腔の狭小化をきたしたものと思われた.血管輪には気管軟化症に伴う気管狭窄が知られているが,その他の機序による気管狭窄も念頭に入れ早期診断と適切な治療法の選択が望まれる.