Large anisotropy in the magnetic susceptibility of metallic carbon nanotubes.

Through magnetic linear dichroism spectroscopy, the magnetic susceptibility anisotropy of metallic single-walled carbon nanotubes has been extracted and found to be 2-4 times greater than values for semiconducting nanotubes. This large anisotropy can be understood in terms of large orbital paramagnetism of metallic nanotubes arising from the Aharonov-Bohm-phase-induced gap opening in a parallel field, and our calculations quantitatively reproduce these results. We also compare our values with previous work for semiconducting nanotubes, which confirm that the magnetic susceptibility anisotropy does not increase linearly with the diameter for small-diameter nanotubes.

Demonstration of double-chambered right ventricle on myocardial perfusion SPECT.

A 19-year-old man with a double-chambered right ventricle (DCRV) and an associated ventricular septal defect was admitted to the hospital for surgical correction. Preoperative study of myocardial perfusion with Tc-99m tetrofosmin SPECT depicted the two chambers of the right ventricle. There was a substantial differential in the radioactive uptake between these two chambers. The inflow and outflow chambers with different peak-pressures (94 and 18 mm Hg) showed different uptakes reflecting the pressure difference, which was intense in the inflow chamber and weak in the outflow.

[Late arrhythmias after the Fontan operation].

To study the incidence of late postoperative arrhythmias and to assess the possible risk factors related to such arrhythmias after the Fontan operation, we retrospectively reviewed standard 12-lead electrocardiogram (ECG) and Holter monitoring (Holter) of 21 patients who survived the Fontan operation between September 1982 and December 1992. Late postoperative supraventricular arrhythmias were detected in 7 of 21 patients by ECG, and in 10 of 17 patients by Holter. Older patients undergoing the Fontan operation had greater incidence of late postoperative supraventricular arrhythmias than younger patients. Patients undergoing superior vena cava-pulmonary artery anastomosis to prevent the right atrial distension had less incidence of late supraventricular arrhythmias detected by Holter. Thus, supraventricular arrhythmias are common in patients after the Fontan operation and may cause morbidity and mortality. Therefore, it is important to prevent the development of late arrhythmias by procedures designed to reduce atrial pressure at younger age.

[A successful surgical treatment for type IA cor triatriatum with an unroofed coronary sinus].

The combination of type IA cor triatriatum (Lucas-Schmidt's classification) and unroofed coronary sinus is very rare in congenital heart diseases. We have presented the first successful surgical treatment for an infant who had this combination. The patient was 10-month-old infant who admitted with cardiac murmur and short stature. Echocardiography revealed that an abnormal septum in the left atrium and dilated coronary sinus. Under cardiopulmonary bypass she underwent surgical treatment which consisted of a resection of the intra-left-atrial diaphragma, closure of ASD with an equine pericardial patch. During operation, unroofed coronary sinus (partially unroofed terminal portion of the coronary sinus) was revealed. Her postoperative course was uneventful.

Pulmonary arterial changes in patients dying after a modified Fontan procedure following pulmonary artery banding.

Pulmonary arterial changes were histometrically analyzed in four cases of postoperative death following a modified Fontan procedure in which pulmonary artery banding had previously been performed because of pulmonary hypertension. Case 1 was a 3-year-old girl with corrected transposition of the great arteries (TGA), ventricular septal defect, and double-inlet left ventricle; case 2 was a 6-year-old girl with single ventricle (SV) and complete TGA; case 3 was a 25-month-old boy with SV and double-outlet right ventricle; and case 4 was a 21-year-old man with tricuspid atresia. The cause of death in cases 1, 2, and 3 was pulmonary hypertensive crisis due to postoperative vasoconstriction of the small pulmonary arteries. Medical hypertrophy remained in half of the preacinar small pulmonary arteries although it was not observed in all the intraacinar arteries in cases 1 and 2, even after banding. The postoperative course of case 4 was uneventful despite multiple thromboembolism in the small pulmonary arteries. However, the patient died due to a thrombosed artificial valve. The results suggest that residual medial hypertrophy of the small pulmonary arteries was a major risk factor in these cases. Lung biopsy is recommended to determine the indications for the Fontan procedure in these hemodynamically critical cases.

Pulmonary vascular disease and operative indications in complete atrioventricular canal defect in early infancy.

Pulmonary vascular disease was morphometrically analyzed in 67 patients (mean age, 19 months) with isolated complete atrioventricular canal defect. Complete obstruction of the small pulmonary arterial lumen resulting from acute fibrous proliferation and atrophy of the peripheral arterial media, which were considered absolute operative contraindications, were characteristic in six patients with Down's syndrome. Morphometric analysis of medial thickness revealed that thinning of the media of the small pulmonary arteries is generally observed at around 6 months of age in patients with complete atrioventricular canal defect and that the media in patients who have complete atrioventricular canal defect and Down's syndrome was thinner than that in such patients without Down's syndrome. These results suggest that thinning of the media as a result of two factors--Down's syndrome and aging--facilitates the rapid occurrence of fibrous intimal proliferation. Therefore intracardiac repair is desirable within 6 months of life, before medial thinning, in patients with complete atrioventricular canal defect and Down's syndrome. Excluding patients with absolute operative contraindications, the scores of the index of pulmonary vascular disease in operative survivors were below 2.0 and death occurred when scores were more than 2.2. The pulmonary vascular resistances measured in room air and by the oxygen inhalation and tolazoline tests in patients with operative contraindications were more than 7.3, 3.8, and 6.6 units.m2, respectively. We thus conclude that lung biopsy should be undertaken for patients in whom pulmonary vascular resistance is beyond these values to determine the appropriateness of surgical intervention.

[Surgical treatment of double-outlet right ventricle with left ventricular outflow tract obstruction].

Three patients with double-outlet right ventricle (DORV) and left ventricular outflow tract obstruction (LVOTO) were described. In each patient, LVOTO was produced by restrictive VSD which resulted from malalignment of the conal musculature and a discrete subaortic membrane. All patients underwent surgical repair with enlargement of the ventricular septal defect and rerouting of the outflow tract from the left ventricle to the aorta. One patient died of congestive heart failure three months postoperatively. Causes of LVOTO and surgical management of DORV with LVOTO were discussed.

[Closure of median sternotomy incision with EPTFE sutures].

EPTFE (CV-0) suture was utilized for closure of median sternotomy incision in 100 patients under 6 years of age who underwent open heart surgery. During 3 years follow up, except for one dislocation of sternum, all patients have healed without complication. EPTFE suture is swanged to a needle that has the same diameter as the thread, which reduces bleeding from the needle hole. It is radiologically lucent, and therefore does not disrupt chest X-ray, angiography or MRI investigations, in contrast to sternal wires. In addition, in the case of life threatening postoperative complication, EPTFE suture allows rapid and simple access to the heart, without the need to cut wires. We concluded that EPTFE suture can be utilized for closure of median sternotomy in patients under the age of six, without an increased risk of postoperative or long-term complications.

[A case report of patch aortoplasty for supravalvular aortic stenosis associated with Williams syndrome].

A 15-year-old girl underwent patch aortoplasty for supravalvular aortic stenosis in association with Williams syndrome. Pressure gradient of before and after stenosis of the aorta decreased from 104 mmHg to 16 mmHg at the postoperative catheterization. Angiography after the operation showed no stenosis. Postoperative course was excellent and discharged on 14th postoperative day. The problems of the operation of supravalvular aortic stenosis were discussed.

[Surgical treatment of pulmonary atresia with intact ventricular septum in infancy--analysis of right ventricular growth potential after pulmonary valvotomy].

Our surgical experience involving pulmonary atresia with intact ventricular septum (PPA) between the years 1981 and 1989 is reviewed. Twelve infants aged 3 days to 11 months were studied for right ventricular growth potential with angiocardiography and hemodynamics after transventricular pulmonary valvotomy (TVPV). Ten infants were divided into two groups, 5 infants (Group I) were treated with TVPV only, and the other 5 infants (Group II) required additional surgery after the initial operation (TVPV in 2 cases and TVPV with shunt in 3 cases). Post-operative RV growth potential was evaluated with right ventricular index (RVI) based on the tricuspid valve annulus, right ventricular inlet, and right ventricular outlet dimensions, and with tricuspid annular index (TVI) based on the tricuspid valve annulus normalized by aortic diameter. Follow-up (3-69 months after initial operation) studies demonstrated that the RV cavity increased in Group I (RVI of 15.75 +/- 2.92 preoperatively versus 17.00 +/- 1.57 postoperatively, TVI of 3.04 +/- 0.63 versus 3.85 +/- 0.40). In contrast, the RV cavity in Group II demonstrated a lack of growth (RVI of 9.24 +/- 2.60 versus 9.85 +/- 2.76, TVI of 1.46 +/- 0.46 versus 1.70 +/- 0.80). PPA infants with RVI greater than 11 have been treated successfully with TVPV alone, which may maximize the potential for RV growth, but infants with RVI less than 11 have not experienced RV growth + postoperatively and, therefore, have required second intracardiac operations.

[Modified Fontan operation of single ventricle with D-TGA].

An 8-year-old boy who had previously received two systemic pulmonary shunts, underwent successfully direct anastomosis between SVC and right pulmonary artery (bidirectional Glenn shunt), and proximal side of SVC and main pulmonary artery. Post operative course was uneventful with pleural effusion during a shot period. Post operative right atrial pressure was 9/5 mmHg without evidence of live swelling.

[Effectiveness of the bidirectional Glenn shunt for the univentricular heart].

Two cases underwent a modified Fontan operation with simultaneous superior vena cava-right pulmonary artery end-to-side anastomosis, which we called "bidirectional Glenn shunt". This anastomosis seems to be so effective for reduction of right arterial volume loading, and could proved life-saving in the case with the acute obstruction at the site of the right atriopulmonary artery anastomosis immediately after surgery.

[A long-term prognosis of ventricular septal defect associated with aortic regurgitation].

Fifty-one cases of ventricular septal defect associated with aortic regurgitation (VSD and AR) were examined for past twenty-two years. Only VSD closure was performed for AR cases under Sellers II regurgitation. After the average of 11.6 years' follow-up, 14 cases retained over 60 mmHg of diastolic pressure and belonged to NYHA functional class 1. VSD closure and aortic cusp suspension were performed for AR cases over Sellers II regurgitation. Three cases operated before 1969 died of cardiac failure and one case recently died of infectious endocarditis (IE). Because of residual AR, one case was performed re-aortic cusp suspension one year after the operation and another case was scheduled for re-aortic cusp suspension after three years and eight months. Eighteen cases with malfunctioned valve caused by calcification, etc. underwent the aortic valve replacement. Early death was due to low cardiac output syndrome (LOS). Five cases were followed up for eleven years on the average. Two cases were found atrial fibrillation and myocardial infarction, respectively. Four cases were VSD + AR with the past history of IE and one died of LOS after surgery. Two cases were postoperative IE. One died three months after the operation and the other is doing well after the re-surgery by translocation. A long-term finding of SV1 + RV5 by electrocardiogram showed a significant decrease in left ventricular overload. Significant decrease of cardiothoracic ratio was observed in AR group under Sellers II regurgitation. Pulse pressure was significantly decreased as well.