Search PubMed⌕ Search

Biomedical subjects

T Iwa

Publications and source records attributed to T Iwa.

At least 55 records · Page 3Linked to original sources
PubMed1991

Ventricular assistance by right free wall dynamic cardiomyoplasty following acute right heart failure in canines.

The efficacy of right ventricular assistance provided by electrically conditioned skeletal muscle was studied in 17 canines. The right ventricular free wall was made ischemic and akinetic by ligating all coronary branches supplying it. The latter procedure led to deterioration of hemodynamic parameters. After that, 14 canines were divided into two groups: group 1 (n = 8) was observed without cardiomyoplasty for 2 hours; group 2 (n = 6) underwent right ventricular dynamic cardiomyoplasty with the conditioned left latissimus dorsi. The deterioration in hemodynamic parameters in group 1 showed no further significant change during the period of observation. In group 2, right ventricular function was augmented by cardiomyoplasty, as shown by a significant increase in right ventricular and pulmonary artery pressures. In addition, decreased CVP suggested improved right ventricle (RV) filling. Right ventricular function curves obtained by volume loading in a further group of three canines, group 3, also demonstrated improved right ventricular function. Thus right ventricular dynamic cardiomyoplasty appears to contribute significantly to right ventricular function in a model of acute right heart failure.

Acute Disease↗
PubMed1991

Ex vivo performance of muscle powered cardiac assist device: potential for right ventricular support.

The present study addressed the filling sensitivity and power output of the TOYOBO VAD (TVAD) and Utah soft artificial ventricle (USAV) to evaluate these pumps as a muscle powered cardiac assist device (MCAD). Two pumps were assembled with three different types of driving chambers placed underneath the latissimus dorsi (LD) muscle: the soft spindle (SS) type, elastic spindle (ES) type and bellows (B) type. The USAV required a filling time of greater than 1000 msec at any preload with any driving chamber, although the TVAD allowed this only with the ES-type chamber assembly. In an ex vivo mock study, the ES- and SS-type chamber assembly demonstrated a maximum stroke volume (SV) of 7.7 mL (39% stroke) by the USAV and 12 mL (17% stroke) by the TVAD at an afterload below 20 mmHg. On the other hand, the B-type chamber increased SV according to afterload in both pumps, resulting in a maximum SV of 25 mL (36% stroke) by the TVAD and 7.6 mL (38% stroke) by the USAV at a 30 mmHg afterload. The maximum stroke work (SW) achieved was 1.3 x 10(6) erg by the TVAD and 0.5 x 10(6) erg by the USAV, which exceeds that of the canine right ventricle. In conclusion, the ES-type chamber provided best pump filling and the B-type chamber best pump ejection, but back pressure at the chamber diaphragm determined performance efficiency. An active filling mechanism for the driving chamber will be necessary to offset the low preload requirements of a VAD, and provide the maximum power output necessary for right ventricular support.

Back↗
PubMed1991

Transesophageal echocardiographic monitoring during coronary artery bypass surgery.

To demonstrate serial changes of left ventricular (LV) function during coronary artery bypass grafting surgery, transesophageal echocardiography (TEE) was used in 17 patients. The cross-sectional image of the left ventricle at the level of the papillary muscles was monitored, and was analyzed immediately in the operating room using a computer-assisted cine-memory function. Global LV function was evaluated by measuring LV end-diastolic and end-systolic area and computing the fractional area change (FAC). Segmental wall motion abnormalities (SWMA) were graded according to a scoring system. During the operative procedure before sternal closure, 5 patients showed SWMA with a simultaneous decrease in FAC to under 40%, and 9 patients showed SWMA without FAC depression. Two-thirds of new SWMA improved after myocardial revascularization. All 17 patients showed a change of interventricular septal movement at the end of the operation. FAC improved from a mean value (+/- SD) after intubation of 47.6 +/- 10.7% to a mean value after revascularization of 58.5 +/- 13.0% (p less than 0.05) and to a mean value at the end of the operation of 55.9 +/- 12.2% (p less than 0.05). Thus: 1) global and regional LV function improved immediately after myocardial revascularization with administration of inotropic agents; 2) a significant change of interventricular septal movement occurred after sternal closure; and 3) intraoperative TEE monitoring is a safe, simple, and effective method for evaluating LV global and regional function.

Adult↗
PubMed1991

Diagnosis and treatment of left ventricular false aneurysm.

Three patients are presented in whom a false aneurysm of the left ventricle was surgically treated. False aneurysm of the left ventricle is an unusual consequence of ventricular wall rupture with containment of the resulting hematoma. Most false aneurysms of the left ventricle develop following myocardial infarction. The false aneurysm wall contains no myocardium. The false aneurysm has a great tendency to rupture, regardless of its size. One patient developed progressive congestive heart failure following a myocardial infarction. The other two patients were asymptomatic following myocardial infarction. Preoperative magnetic resonance imaging showed characteristics of a false aneurysm. These included a distinct discontinuance of the myocardium at the neck of the aneurysm and a narrow neck relative to the diameter of the aneurysm. Two patients underwent successful closure of the orifice of the false aneurysms. One patient underwent emergency surgery because of acute rupture while awaiting surgery but died of cerebral damage. Surgical correction of a false aneurysm is clearly advisable even in the absence of symptoms.

Echocardiography↗
PubMed1991

Comparative study of five preoperative methods for the localization of accessory pathways in the Wolff-Parkinson-White syndrome.

One hundred and thirty-four cases of Wolff-Parkinson-White syndrome were studied to evaluate the relative usefulness of electrocardiography (ECG), electrophysiological studies (EPS), body surface mapping (BSM), gated blood-pool phase analysis (nuclear studies), and vectorcardiography (VCG) in the localization of the accessory pathway (ACP). In comparison with the final localization verified by intraoperative studies, 93.4% in 8-region ACP localization (97.7% in 4-region ACP localization) could be correctly localized by ECG using our criteria, 83.9% (86.8%) by EPS, 82.6% (95.8%) by BSM, 78.8% (87.7%) by nuclear studies, and 67.3% (78.0%) by VCG. It was concluded that: (a) ACP can be localized preoperatively with considerable accuracy by using our simple ECG criteria. (b) The EPS method has some limitation, especially with respect to 8-region ACP localization. (c) Our observation showed no evidence that BSM, VCG, or nuclear studies were superior to ECG in ACP localization. (d) Among the 5 methods studied, ECG and EPS appear to be the appropriate procedures for preoperative ACP identification.

Adolescent↗
PubMed1991

Mediastinal nodal involvement and the prognosis of non-small cell lung cancer.

We evaluated the effect of mediastinal lymph node metastasis on survival in 233 non-small cell lung cancer patients (N2 disease in 199 patients and N3 disease in 34 patients). Of the 199 patients with N2 disease, 144 underwent curative resection. The five-year survival rate of these 144 patients was 20.3 percent, which was significantly better than that of either the noncuratively resected N2 group or the N3 group. Nodal metastases in the curatively resected patients involved superior and inferior mediastinum irrespective of the location of the primary tumor. Patients with right-sided N2 lesions and metastases to the superior mediastinum had a worse survival than those with metastases to the inferior mediastinum. In contrast, patients with left-sided N2 lesions metastasizing to the inferior mediastinum had a significantly worse survival than those with lesions metastasizing to the superior mediastinum. Patients with single-level metastases had a significantly better survival rate than those with multilevel metastases. Subcarinal nodal involvement had an unfavorable effect in case of single-level metastasis, but did not affect the survival in cases of multilevel metastases. Our present study indicated that the survival of patients with N2 disease was affected by the operative radicality, by the number of levels of metastases, and also by the location of the nodal involvement. It seems appropriate that extensive mediastinal dissection should be performed irrespective of the location of the primary tumor.

Adenocarcinoma↗
PubMed1991

Functional advantage of parenchymal-sparing surgery for early hilar lung cancer.

In a group of 27 patients with early hilar lung cancer, standard sleeve lobectomy was performed in 14 cases, standard lobectomy in 9 cases, and another 4 patients underwent parenchymal-sparing operations (2 had sleeve segmentectomy, 1 had sleeve middle lobectomy, and 1 had left second carinal resection). The changes of conventional pulmonary function tests and regional pulmonary function were compared between patients undergoing sleeve lobectomy and those undergoing parenchymal-sparing surgery. The parameters used for the conventional lung function tests were FVC, %FVC, FEV1.0, and %FEV1.0. For the evaluation of regional pulmonary function, perfusion scans using 99mTc-MAA and ventilation scans using 133Xe were performed. The decrease of FVC in the sleeve lobectomy group (n = 5) was 724 +/- 182.7 ml, whereas that in the parenchymal- sparing surgery group (n = 4) was 367.5 +/- 52.1 ml, a significant difference. Both the FEV1.0 and %FEV1.0 showed no marked changes in both groups between the preoperative and postoperative values. Perfusion and ventilation scans in the parenchymal-sparing group showed a superior result in comparison with sleeve lobectomy group. All the patients undergoing parenchymal-sparing operations survived over the long term. It was thus concluded that parenchymal-sparing surgery can be applied to carefully selected patients with tiny localized cancers.

Aged↗
PubMed1991

Proposals regarding some deficiencies in the new international staging system for non-small cell lung cancer.

The new international staging system remains a source of some controversial issues as the survival of 716 non-small cell lung cancer patients in our series (286 in stage I, 63 in stage II, 225 in stage IIIA, 81 in stage IIIB and 61 in stage IV) is analyzed with regard to the T, N and M categories. The problems are aired and some proposals made for revising the staging system. Multivariate analysis of significant factors contributing to the prognoses of stage I patients made it clear that the most important factor was the size of the primary tumor. A significant difference in survival was found between T1N0M0 and T2N0M0 disease. Furthermore, patients having tumors larger than 5 cm in diameter showed a significantly worse prognosis than those having tumors less than 5 cm. Accordingly, stage I should be divided into stage IA (T1N0M0, tumors less than 3 cm) and stage IB (T2aN0M0, tumors less than 5 cm). Tumors greater than 5 cm should be categorized as T2b, and T2bN0M0 disease should be classified as stage II. Patients having N2 disease involving the pretracheal (#3) node had a significantly worse survival rate than those with other ipsilateral nodal involvement, so #3 nodal involvement should be categorized as N3 disease. Patients having ipsilateral intrapulmonary satellite nodules, most of which were verified by microscopic examination of the resected specimens, had a significantly better survival rate than stage IIIB patients and showed no significant difference from stage IIIA disease. Accordingly, ipsilateral intrapulmonary satellite lesions should be categorized as T3 disease.

Aged↗
PubMed1991

[A case of pulmonary varices in which enhanced CT was useful for diagnosis].

A case of pulmonary varices in a 73-year-old female is presented. Routine chest X-ray revealed a mass in the right hilar region. CR tomogram showed a round, clearly defined mass at the right hilum. Computed tomography demonstrated marked enlargement of the proximal portion of the pulmonary vein at the entrance of the left atrium, which was suspected to be pulmonary varices. The diagnosis was confirmed by pulmonary angiography. During the arterial phase no abnormal findings were seen, but during the venous phase the veins of the right upper and middle lobes were found to be draining into the dilated pulmonary vein and then into the left atrium. Thus, the diagnosis of pulmonary varices was established. CT and angiography are the most useful methods for definitive diagnosis of pulmonary varices.

Aged↗
PubMed1991

[Transesophageal echocardiography during coronary bypass surgery].

The early diagnosis of intraoperative myocardial ischemia is important because such ischemia can lead to myocardial infarction. Clinical effectiveness of transesophageal echocardiography (TEE) was evaluated for detecting intraoperative myocardial ischemia and for observing the recovery of cardial motion at the end of cardiopulmonary bypass (CPB) in 20 patients who had undergone CABG. After endotracheal intubation, the TEE transducer was introduced into the esophagus to obtain a short axis cross-sectional view of the left ventricle at the level of the papillary muscles. Global LV function was assessed by measuring end-diastolic and end-systolic areas, which were calculated automatically, and the fractional area change (FAC). Regional endocardial wall motion was also analyzed by subdivision into four anatomical segments. The mean FACs were 48% after intubation, 47% after skin incision and 48% after sternotomy. Thereafter it increased significantly to 59% 30 minutes after CPB and 56% at the end of the operation. Thus, global LV function was improved significantly by revascularization. TEE could detect myocardial ischemia more sensitively than ECG. In 9 patients, FAC decreased significantly and new regional wall motion abnormality (RWMA) appeared around the time of sternotomy, but no ECG changes were detected. In another 7 patients, new RWMAs were detected without either a decrease in the FAC or ECG changes. It was found that myocardial ischemia took place more frequently before the initiation of CPB than expected. The recovery of left ventricular wall motion from cardioplegic arrest was able to be monitored visually during the period of weaning from CPB and the TEE could facilitated prompt and exact judgement of weaning from CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[The use of Doty's extended aortoplasty in binovular twins with congenital supravalvular aortic stenosis].

Binovular twins with congenital supravalvular aortic stenosis underwent Doty's extended aortoplasty. Neither twins displayed signs of Williams syndrome. Peak systolic pressure gradients of 65 and 70 mmHg, respectively, were measured across the stenotic portion at the ascending aortae. After surgery, the pressure gradients were reduced to 15 and 20 mmHg, respectively, at the aortic valves. No new aortic regurgitation was observed postoperatively. It is important that the ascending aorta, including the stenotic part, is symmetrically incised into the noncoronary and the right coronary sinus of Valsalva. The fibrous ring should be removed as completely as possible. Doty's extended aortoplasty is a safe and effective procedure for supravalvular aortic stenosis.

Aorta↗
PubMed1991

[Physical and biophysical aspects of high energy intracardial electrical discharges. 4. Effects of fulguration beads in an isotropic diphasic medium].

Study of the effects of fulgurating electric shocks on an isotropic protein gel more supple than ordinary myocardium provides better understanding of the mechanical effects of fulguration on biological tissues. With a shock and energy level of the type used clinically, a central crater is produced measuring 4 to 6 mm in diameter and a few millimetres deep, surrounded by a crown 30 mm in diameter. Damage due to the mechanical effects of fulgurating shocks is thus 3 to 15 times greater than the size of the electrode. The size of lesions is generally proportional to the energy level and is greater at the anode than cathode. It is also greater with impulses having a short rise time. When the electrode is almost parallel to the wall, the surface area of mechanical lesions is larger and more irregular and it is less deep than when the electrode is perpendicular to the gel.

Biophysical Phenomena↗
PubMed1991

[Assessment of coronary bypass surgery by continuous ventricular function monitoring].

The sequential change of left ventricular function during exercise and recovery after exercise was assessed in 50 patients who had undergone coronary bypass surgery before and after the operation by means of continuous ventricular function monitoring system (VEST). Cardiac response was divided into 4 types with respect to the profiles of the left ventricular ejection fraction during exercise. Type A continued to increase; type B initially increased but decreased in severe exercise stages; type C did not change during exercise; type D continued to decrease. Most patients showed type C or D before surgery but showed type A after surgery. 9 patients with occluded grafts or ungrafted coronary arteries showed type B, C or D. Two patients with extended infarction and poor left ventricular function showed type C after surgery. In recovery period after exercise, the ejection fraction showed an overshoot. The mean ratio of peak ejection fraction during recovery to ejection fraction at rest increased from +62 +/- 12% before operation to +68 +/- 16% after operation (p less than 0.05). The recovery time after exercise was decreased from 195 sec before operation to 98 sec after operation (p less than 0.01). VEST revealed response of left ventricular function during exercise and recovery after exercise as far as detail abnormalities.

Adult↗
PubMed1991

[Cardiac function during exercise in patients with coronary bypass surgery assessed by continuous ventricular function monitoring].

The response of left ventricular function during exercise and recovery after exercise was assessed in 52 patients with coronary artery bypass surgery by means of a radionuclide continuous ventricular function monitor. This system consists of 2 radionuclide detectors, recorder and a computer. After the equilibration of 20 mCi technetium 99m-labeled autologaous red blood cells into the intravascular space, the beat by beat radionuclide data were summed for 20-sec intervals to measure left ventricular ejection fraction (EF). Before surgery, the mean EF decreased with exercise from 51 +/- 9% to 45 +/- 11% (p less than 0.001). Cardiac response was divided into 4 types according to the profiles of the EFs during exercise. In 6 patients, EF continued to increase until maximal exercise (type A). In 10 patients, EF initially increased and then decreased in late exercise stages (type B). In 9 patients, EF did not change significantly during exercise (type C). In 27 patients, EF decreased throughout exercise (type D). After surgery, the mean EF increased with exercise from 53 +/- 10% to 60 +/- 13% (p less than 0.001). Thirty-five patients showed type A, 9 type B, 5 type C, and 3 type D. Two type D and 5 type B patients had occluded grafts or ungrafted coronary arteries. Four patients with complete revascularization including an internal thoracic artery and saphenous vein grafts showed type B. Three patients with extensive infarction and poor left ventricular function showed type C.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Postoperative percutaneous coronary angioplasty for stenosed aortocoronary vein bypass].

This paper was presented to demonstrate the efficacy of postoperative PTCA for varying degree of stenosis aortocoronary bypass with saphenous vein grafts. The following conclusions were drown. 1. The success rate of postoperative PTCA for 15 grafts showed 88.8%. 2. The rate of success for PTCA was much more effective in patients within one year after bypass operations. The authors concluded that postoperative PTCA can be done with excellent rate of success. Therefore, postoperative cine-coronary angiography should be done to evaluate the state of the graft and to decide to perform possible postoperative PTCA in order to keep long time patency rate of saphenous vein grafts.

Adult↗
PubMed1991

[Clinical significance of immunotherapy for lung cancer--present and future].

To evaluate the clinical efficacy of OK-432 immunotherapy as an surgical adjuvant for lung cancer patients, three kinds of randomized controlled trials were done. In the first trial, patients were randomized into two groups: an immunochemotherapy (IM-C) group and a chemotherapy (control) group. For IM-C group, OK-432 (2KE/w) was injected intramuscularly for three years. Significant improvement of the survival rates in the IM-C group was noted in the following items: all resected cases, stages I+II cases, stage III cases, completely resected cases, incompletely resected cases and cases with epidermoid carcinoma. However, in comparison to adenocarcinoma there was no significant difference between the two groups. In the second trial, patients were randomized into an intramuscular injection group and an intradermal injection group. In comparisons to the survival rates, there were no significant differences between the two groups. In the third trial, stage I patients were randomized into a group treated with intradermal injection (5KE/w) and no adjuvant group. To date, there was no significant difference between the two groups. It is concluded that OK-432 immunotherapy, with concomitant use of chemotherapy, have favourable effect on the patient with squamous cell carcinoma. No definitive difference of clinical effects between intramuscular injection and intradermal injection.

Humans↗
PubMed1991

[Evaluation of surgical indication for the small lesion of advanced lung cancer].

This report analyzes the operative indication for the small lesion of advanced lung cancer. The subjects consisted of 25 patients with T1N2 lung cancer, one T1N3, four T1M1 and five small lung cancer lesion with dissemination, which was regarded as the small lesion of advanced lung cancer. The cumulative 5-year survival rate after operation for 25 patients with T1N2 lesion was 30.6%. Of 25 patients, 18 were selected patients who underwent a curative operation with a 5-year survival of 37.0%. In the remaining 7 patients, who underwent a non-curative operation, 5-year survival was 0%. As to mediastinal lymph node involvement, it is possible that metastasis to more than two levels of mediastinal lymph nodes or to the upper mediastinal lymph nodes (#1-3) are poor prognostic factors in T1N2 lesion. Another group except T1N2 could not be the comparative materials because they were much fewer in number. But T4 cases associated with small lung cancer lesion with dissemination and T1M1 cases associated with intrapulmonary metastasis encountered at thoracotomy could be expected to have a long-term survival. We conclude that T1N2 patients with metastasis to within one level of mediastinal lymph node, which will possibly have a curative operation, is a proper operative indication for the small lesion of advanced lung cancer.

Adenocarcinoma↗