Keiichi Mukai

Myocardial Coagulation by Intraoperative Nd:YAG Laser Ablation and Its Dependence on Blood Perfusion

To investigate whether the efficacy of intraoperative laser ablation therapy is affected by myocardial blood perfusion, we irradiated 11 canine hearts through the epicardium with a Nd:YAG laser (10, 20. and 30 J/mm2) using air as the medium. Compared coagulated myocardial depth, width, and volume obtained in the red beating heart was compared with those in the white nonbeating heart infused with CC saline (cardioplegic model) via the coronary artery. Histologically, the macro‐ and microscopical findings were very similar. At each level of energy, the width and volume of red myocardium coagulated were significantly larger than those of white myocardium (P < 0.01). At 30 J/mn2, the depth of coagulation of red myocardium was significantly larger than that of white myocardium (P < 0.01). The coagulated volume of the white myocardium was about 60% of that of the red myocardium. NdiYAG laser energy was absorbed by blood (red color = hemoglobin), and more energy was transferred in the higher temperature myocardium. During intraoperative Nd:YAG laser ablation, the presence of blood perfusion in cardiac tissue is thought to be an important factor affecting safe irradiation.

Late patency of the left internal thoracic artery graft in patients with and without previous successful percutaneous transluminal coronary angioplasty

The aim of this study was to compare early and late graft patency in patients with and without previous successful PTCA. Of the 70 patients who received both early and late follow-up angiography, 13 patients who had received successful PTCA at the left anterior descending coronary artery (LAD) before CABG (group I) and 31 patients who had not received preoperative PTCA in any vessel (group II) were retrospectively reviewed. There were no significant differences in patient characteristics including major coronary risk factors. The mean duration between the operation and control angiography was 35+/-23 months in group I and 36+/-19 months in group II (P=0.90). Occlusions of the LITA graft were observed in four patients of group I and in four patients of group II. Cumulative patencies of the LITA graft were 54% in group I and 83% in group II (P=0.12). The late patency rate of the LITA graft bypassed to the LAD in patients that received previous successful PTCA in the coronary artery tended to be lower than in patients without previous PTCA. This result should be confirmed by further prospective studies.

Congenitally corrected transposition of the great arteries associated with the pre-excitation syndrome.

A case with congenitally corrected transposition of the great arteries associated with the pre-excitation syndrome is presented. A gated-blood-pool study and Tl- 201 myocardial imaging were performed using SPECT. The tomographic gated-blood-pool images showed the shapes of the right ventricle (RV) and left ventricle (LV), i.e., anatomically LV and RV respectively, to be reversed from that of normal patients. The relationships of the great vessels and ventricles also were easily visualized. RV hypertrophy (anatomical LV) was visualized on the TI-201 images. Phase analysis showed the earliest excitation was in the anteroseptal region near the base of the LV, which was consistent with the site of the accessory conduction pathway. The gated-blood-pool and TI-201 tomographic studies were helpful for demonstrating the corrected transposition of the great arteries and the pre-excitation syndrome.

Surgical treatment of the Wolff-Parkinson-White syndrome in infants and children.

Eleven pediatric Wolff-Parkinson-White (WPW) syndrome patients underwent surgery. Four had left, 5 right cardiac type and 2 had right septal type WPW syndrome. Two patients had 2 accessory conduction pathways (ACP). Ebsteins anomaly and secundum type atrial septal defect were the associated congenital cardiac diseases in one patient each. Indications for surgery included repeated and/or long-lasting paroxysmal supraventricular tachycardia (PSVT), ineffective drug therapy, cardiac failure due to frequent tachycardia, short effective refractory period of the ACP, and simultaneous surgery for associated congenital cardiac diseases. Pre- and intra-operative examinations, including ECG, VCG, UCG, body surface mapping, intracavitary recording by catheter electrodes, computerized epicardial mapping, and endocardial mapping, were performed for the precise localization of the ACP. The surgical method was basically the same as is used for adults. Anterior median stermotomy was used primarily in right cardiac and right septal type and left anterior thoracotomy was used in 3 of 4 cases of the left cardiac type. Eight of 11 cases, two of which had 2 ACPs, were completely cured and in 3 there was evidence of postoperative pre-excitation. However, the PSVT attacks disappeared almost completely and drug therapy is not required at present.