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Biomedical subjects

T Iwa

Publications and source records attributed to T Iwa.

At least 145 records · Page 8Linked to original sources
PubMed1988

[Radio frequency catheter ablation of the atrioventricular conduction system in a canine model].

Twenty dogs underwent catheter ablation of the AV conduction system with monopolar 300 KHz output to assess the efficacy and the safety of using radio frequency energy at catheter ablation. The energy (15 to 120 W) was delivered between the distal electrode and the back pad until 3 second after complete AV block, which was certified at ECG monitoring. Pathological observation was done with 7 dogs in 2 hours, 6 dogs in 4 to 7 weeks and compared with 10 dogs which underwent catheter ablation with DC energy. Complete AV block was achieved in 15 dogs and there was no return of AV conduction during observed period. The QRS complex of the escape rhythm was similar to those found in sinus rhythm in all dogs. Complete AV block was achieved only when the catheter was located where the H-V interval was longer than 26 msec at the His bundle electrogram before ablation. The damaged area was limited near His bundle and well delineated. AV node was intact in all dogs. Electron micrograph of the damaged areas in acute phase showed the swelling of mitochondria without broken cytoskeletal filaments, which indicate there were no mechanical shocks. There was no patchy fibrosis seen in chronic phase. I conclude that the catheter ablation of the AV conduction system with radio frequency energy is effective and safe, and the minimal damage of the tissue suggests the benefit and the possibility of clinical use.

Animals↗
PubMed1988

Measurement of regional myocardial blood flow. Application of the electrolytic hydrogen clearance method in man.

To assess myocardial perfusion intraoperatively and to evaluate the adequacy of coronary bypass grafting, we measured regional myocardial blood flow by the electrolytic hydrogen clearance method in 49 patients. Group I comprised 10 patients with nonischemic heart disease and group II, 39 patients with ischemic heart disease undergoing coronary bypass grafting. Group II was subdivided according to the percent stenosis of the coronary arteries supplying the ventricular regions: group IIa, less than 75% stenosis; group IIb, greater than or equal to 75% stenosis. Mean myocardial blood flows were 154 +/- 7, 145 +/- 5, and 98 +/- 9 ml/min/100 gm in groups I, IIa, and IIb, respectively (p less than 0.01, group IIb versus groups I and IIa). Mean blood flows were 161 +/- 19, 159 +/- 12, 78 +/- 12, and 59 +/- 15 ml/min/100 gm in areas of the left anterior descending coronary artery with less than 50%, 75%, 90%, and 99% stenosis in group II. In areas with a totally occluded left anterior descending coronary artery with collaterals, mean flow was 90 +/- 15 ml/min/100 gm. The mean myocardial blood flows were 40 +/- 7 and 100 +/- 14 ml/min/100 gm in areas with anterior Q wave and non-Q wave infarction, respectively (p less than 0.01). After cardiopulmonary bypass, the mean flow increased from 99 +/- 11 to 150 +/- 7 ml/min/100 gm in the grafted areas in group IIb (p less than 0.01), but it did not change in group I or IIa. The electrolytic hydrogen clearance method provided quantitative evaluation of myocardial perfusion and recovery from hypoperfusion by coronary bypass grafting. This method was especially useful in patients undergoing mammary artery grafting.

Adult↗
PubMed1988

[Intraoperative ultrasound imaging and its application to cardiovascular operations].

Intraoperative ultrasound imaging was employed for qualitative and quantitative studies during cardiovascular operations in 36 patients. A 7.5M Hz high frequency ultrasound scanner was used to image. The ultrasound probe was sterilized by gas and placed directly on the heart by the hand of surgeon. On the clinical application, 10 cases of patients with coronary artery disease were scanned. Left main trunk and proximal portion of other three branches were visualized and pathological lesions were demonstrated clearly. Four cases of myocardial bridging were observed. Intramyocardial coronary arteries were easily detected and supraarterial myotomy was performed safely. Four cases of valvular disease were examined. We could evaluate valvular anatomy and physiologic aspects of valvular disease and 15 cases of aortic root disease were examined intraoperatively. In aortic root dissection, the size and site of the true and false lumens were clearly demonstrated in all patients. In conclusion intraoperative ultra-sound imaging is a versatile technique with quantitative and qualitative studies of cardiovascular surgery during operation and the perioperative period.

Aortic Dissection↗
PubMed1988

[A rare case of successful surgical treatment of dissecting aortic aneurysm (DeBakey IIIb) associated with total obstruction of the abdominal aorta and acute complicated renal failure].

A rare case of successful surgical management of dissecting aortic aneurysm (DeBakey IIIb) is presented. A fifty-year-old male was admitted to our hospital with a complaint of severe backache and both leg pain. A diagnosis of acute renal failure and assessed total obstruction of the abdominal aorta was made angiographically. Immediate hemodialysis was carried out. After 50 days, a right subclaviafemoral bypass was performed. However, on the 60th postoperative day, plasma creatinine and BUN levels were significantly elevated. A left renal revascularization was performed using saphenous vein graft from the right common iliac artery. The postoperative course was excellent and the creatinine and BUN levels were immediately reduced. And there was no need of hemodialysis postoperatively. Because of difficult management of this kind of complication, extra-anatomic bypass is preferable, instead of total replacement of the dissecting aortic aneurysm. And weaning from such a long term hemodialysis by revascularization of one-kidney is very rare.

Acute Kidney Injury↗