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Biomedical subjects

T Iwa

Publications and source records attributed to T Iwa.

At least 19 recordsLinked to original sources
PubMed1992

Comparative study of eight sets of ECG criteria for the localization of the accessory pathway in Wolff-Parkinson-White syndrome.

Eight sets of electrocardiographic (ECG) criteria for the localization of accessory conduction pathway (ACP) were evaluated on 182 patients with a single ACP. The Rosenbaum criteria identified 78.6% of the left-sided and 94.0% of the right-sided ACPs. Four of the other seven sets of criteria demonstrated a sensitivity higher than 70.9% and six showed a specificity higher than 74.9% in the 4-region ACP localization. The ECG feature of the delta wave polarity in lead V1 correctly localized the ACP to one of three broad regions in 162 of 182 patients with an overall specificity of 94.5%. The study indicates that (1) the 12-lead ECG is of practical value for initial ACP localization; (2) a type A ECG is almost invariably associated with a left-sided ACP, while type B may occur with any ACP location; (3) the polarity of the delta wave is the most important ECG feature, and the polarities of the delta wave and main QRS complex in lead V1 play an important role in ACP localization.

Adult↗
PubMed1992

Comparison of DDD and 'VVI-R like' pacing during moderate exercise: echo-Doppler study.

The non-invasive haemodynamic comparisons of DDD and 'VVI-R like' pacing at rest and during moderate exercise by echo Doppler are reported. Twelve patients (six males, six females, mean age 48.2 years) with a dual chamber pacemaker were submitted to a series of two exercise tests in a semi-supine position, the first test in DDD mode and the second test in a 'VVI-R like' mode: VVT mode, during which pacing rate was externally increased by chest wall stimulation. During the second test, the workload profile was matched to that of the first test (66 watts and same exercise stages) and ventricular pacing rate was incremented via chest wall stimulation and reproduced exactly the heart rate profile of the first test in DDD mode. The heart rate averaged 81 beats.min-1 at rest and reached 116 beats.min-1 during exercise. At rest and throughout exercise tests, aortic blood flow velocity spectra were continuously recorded on video tape and analysed with the calculation program of the echocardiograph. At rest, ejection time, flow velocity integral, flow acceleration and stroke volume differed between DDD and 'VVI-R like' mode while other parameters did not. During exercise all but two parameters differed. DDD mode especially was associated with a larger stroke volume (81.9 vs 70.9 ml; P less than 0.001) and cardiac output (9.24 vs 8.011.min-1; P less than 0.001) than VVI-R mode.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Factors predicting success in DC catheter ablation of accessory pathways.

In a series of 33 patients with accessory pathways, 26 had successful catheter ablation (fulguration [23 patients] or modification [3 patients]) of their accessory pathway conduction, and could be considered as a clinical success. One hundred thirteen single discharge or double discharge shocks were delivered, and each shock was studied to reveal which parameters were important to predict the success or failure of catheter ablation. Double discharge shocks resulted in successful accessory pathway modification or ablation twice as often as single discharge shocks (32% vs 16%). This effect was more pronounced in left lateral accessory pathways (48% vs 4%). Shocks in the electrophysiologically defined ventricular zone were more likely to be successful (33%) than shocks delivered in the atrial zone (14%), irrespective of accessory pathway location. The presence of a probable Kent potential was the parameter most strongly associated with success. The parameter most strongly associated with failure, with a 100% negative predictive value, was the absence of earliest activation recorded on the ablating catheter prior to shock delivery. An AV interval of < 60 msec significantly divided the successful from the unsuccessful shocks (P = 0.01). The VA interval during orthodromic reciprocating tachycardia or right ventricular stimulation did not allow for significant division into successful and unsuccessful attempts in this relatively short series. VA intervals, when longer, were predictive of failure but, when shorter, had low positive predictive value. Mean follow-up in 25 successful patients was 15 +/- 6 months. All patients did well in the follow-up period. Neither those patients with ablation nor modification of the accessory pathway had recurrent episodes of tachycardia or required pharmacological treatment for control of arrhythmias.

Adult↗
PubMed1992

Second surgical intervention for recurrent and second primary bronchogenic carcinomas.

Second operations were performed in 1961-1990 on 23 patients with non-small cell bronchogenic carcinoma, constituting 2.5% of 906 who had undergone pulmonary resection for such tumor and 3.6% of the 641 with apparently curative surgery. The second operation was performed for recurrent tumor in 15 cases and for second primary tumor in eight. Five-year survival after the first operation was 30% in the former group and 88% in the latter (significant difference). Among the total 23 patients, this survival rate was 51%. The study indicates that an aggressive attitude to second surgical intervention is warranted. For early detection of second lesions, follow-up at maximally 6-month intervals should be continued for more than 5 years after the first operation.

Adenocarcinoma↗
PubMed1992

[Current treatment of Wolff-Parkinson-White syndrome and ventricular tachycardia: surgical ablation versus catheter ablation?].

From November 1973, 454 patients with Wolff-Parkinson-White syndrome underwent surgical ablation of accessory pathways. Overall curative rate was 94% in our series including 65 cases of simultaneous surgical repair for combined heart diseases. In recent months, radiofrequency catheter ablation was applied in 7 cases. There has been 2 failures, which have taken more than 2 hours of radiation exposure and have required surgery. There has been 47 patients who underwent surgical ablation for non-ischemic ventricular tachycardia. Forty cases (85%) had a successful outcome of surgical ablation and another 2 cases required DC catheter ablation postoperatively to eliminate ventricular tachycardias. In conclusion, radiofrequency ablation of WPW syndrome in patients without combined heart disease or multiple accessory pathways is feasible. Surgical ablation is effective and safe technique compared with catheter ablation in patients with ventricular tachycardia.

Adolescent↗
PubMed1992

Exercise response assessed by continuous monitoring of ventricular function in patients with coronary bypass operations.

The response of left ventricular function during exercise and recovery after exercise was assessed in 35 patients with coronary artery bypass grafting before and after the operation by means of a continuous ventricular function monitor, which records serial beat-to-beat radionuclide data and calculates left ventricular ejection fractions every 20 seconds. The mean ejection fraction decreased with graded bicycle exercise from 48% +/- 9% to 41% +/- 11% (p less than 0.001) before operation but increased with exercise from 50% +/- 9% to 55% +/- 11% (p less than 0.001) after operation. Cardiac response was divided into four types with respect to the profiles of the ejection fractions during exercise. Type A continued to increase; type B initially increased but then decreased in late exercise stages; type C did not change significantly; type D continued to decrease. Most patients had type C or D responses before operation but type A after operation. Seven patients with occluded grafts or ungrafted coronary arteries had type B or D responses. Three patients with complete revascularization, including an internal thoracic artery and saphenous vein grafts, had type B responses. Three patients with extensive infarction and poor left ventricular function showed type C. In the early recovery period after exercise, most patients had an "overshoot" elevation of ejection fraction. The mean value increased from 59% +/- 10% before operation to 64% +/- 11% after operation (p less than 0.01). The recovery time after exercise was reduced from 2.8 minutes before operation to 1.8 minutes after operation (p less than 0.001). The continuous ventricular function monitor elucidated changes in left ventricular function both during exercise and recovery after exercise, as well as unmasking abnormalities in left ventricular function after coronary bypass operation.

Coronary Artery Bypass↗
PubMed1992

[A case of successful emergency coronary artery bypass grafting surgery for failed coronary angioplasty using percutaneous cardiopulmonary support].

This is the first Japanese case of the successful emergency coronary artery bypass grafting (CABG) surgery for failed percutaneous transluminal coronary angioplasty (PTCA) using percutaneous cardiopulmonary support (PCPS). A 81-year-old woman with old myocardial infarction and angina pectoris is presented. Her coronary angiogram showed the 90% and 50% stenosis of the right coronary artery (RCA) and the total occlusion of the left anterior descending artery (LAD). PTCA for the 90% stenosis of RCA was performed. But, during the balloon dilation, her heart rate and blood pressure decreased. PTCA was stopped. As her chest pain was worse, re-PTCA was tried, using PCPS. Under PCPS (3 l/min), the balloon dilation was performed safely and smoothly. But, the unexpected dissection of RCA occurred, and became larger rapidly. After 85 minutes, the emergency CABG was performed. By using PCPS, the stable hemodynamics was given till the operation. CABG to RCA and LAD was performed safely. After the surgery, the patient progressed well. PCPS was a very useful cardiopulmonary assist device.

Aged↗
PubMed1991

Early hilar lung cancer: its clinical aspect.

Early hilar lung cancers are rare, but are curable if they are properly diagnosed and treated. In the past 14 years, we have treated 27 patients with early hilar cancers that fulfilled the criteria proposed by the Japanese Lung Cancer Society (JLCS). Eighteen patients presented with symptoms and 9 were detected by the mass screening examination of sputum cytology. All lesions in both groups were finally diagnosed by bronchoscopy. Twenty patients (74%) had positive sputum cytology, whereas only 7 (26%) had positive chest X-ray findings. All the patients underwent surgery, and bronchoplasty was the most frequent operative procedure. The 5-year survival rate was 100%, and the 10-year survival rate was 91.7%, as one patient died of a second primary lung cancer in the 6th postoperative year. In conclusion, the definition of early hilar lung cancer proposed by the JLCS is thought to be reasonable, and early hilar lung cancer is a curable disease, if it is properly diagnosed and treated.

Bronchoscopy↗
PubMed1991

Aggressive surgical intervention in N2 non-small cell cancer of the lung.

An aggressive attitude toward surgical treatment was taken in patients with N2 non-small cell lung cancer in the past 10 years. Computed tomographic scanning was employed in the diagnosis of N2 disease, and had a true-positive rate of 57%. Among patients with N2 disease detected by computed tomographic scanning, surgical intervention was attempted except for those with unresectable disease. Of 190 patients with clinical N2 disease, 115 underwent surgical exploration: 9 patients had only an exploratory thoracotomy, 53 patients underwent a curative operation, and 53 had a noncurative operation. The overall 5-year survival rate of these patients was 16% and that of curatively resected patients was 20%. There were 47 patients whose N2 disease was not recognized before operation. The 5-year survival rate of this group was 20% overall and 33% in curatively resected cases. The overall 5-year survival rate of patients with N2 disease who underwent resection (106 with clinical N2 disease and 47 with clinically unrecognized N2 disease) was 17%, and that of the 84 patients undergoing curative operations was 24%. An aggressive attitude toward surgical intervention can be advocated for patients with N2 disease on the basis of our present results.

Carcinoma, Non-Small-Cell Lung↗
PubMed1991

Long-term results of surgery for non-ischemic ventricular tachycardia.

Drug resistant, non-ischemic ventricular tachycardia (VT) was treated in 43 patients by direct surgery based on electrophysiological data. Two main surgical techniques were employed: myocardium was resected followed by cryocoagulation with a special probe in 23 patients with VT originating from the right ventricle. The myocardium was incised followed by cryocoagulation in 10 patients with VT from the left ventricle. The follow-up period ranged from 1 week to 10 years, 4 weeks (mean 3 years, 8 months). After operation, 36 patients (83%) showed complete disappearance of VT without antiarrhythmic therapy. Of these 2 patients died of congestive heart failure not related to VT in the postoperative period at 1 year 4 months, and 2 years 4 months, respectively. In 7 patients, VT remained. In 2, VT disappeared after catheter ablation. In 3 patients, VT became controllable with antiarrhythmic therapy. Operation was not successful in 2 patients (5%); 1 with a giant left ventricular aneurysm died of low cardiac output syndrome due to VT 1 week after operation; the other with arrhythmogenic right ventricular dysplasia originating from both ventricles died suddenly 5 months after operation. The 10-year survival is 89%, and the 10-year freedom from recurrent VT is 83%. These results indicate that surgical management for non-ischemic VT is safe and effective with a high chance of cure.

Adolescent↗
PubMed1991

Coronary artery bypass surgery in patients with angina pectoris and hypothyroidism.

The treatment of hypothyroidism in patients undergoing coronary artery bypass surgery is a difficult clinical problem. To determine perioperative thyroid replacement therapy in patients with hypothyroidism, plasma total thyroxine (T4), total triiodothyroxine (T3), free T4, free T3 and thyroid-stimulating hormone levels were measured preoperatively and at 1, 2, 3, 7, and 14 days after operation in 9 patients with hypothyroidism and were compared with levels in 14 patients with normal thyroid function who underwent coronary bypass surgery. In the normal control group, total T4 decreased to its lowest level on the 1st postoperative day and then increased gradually to the preoperative level at 7 days. Total T4 remained within the normal range throughout the entire postoperative course. In 6 patients with hypothyroidism who were treated with thyroid hormone before surgery, total T4 decreased immediately after operation and only increased after starting thyroid replacement therapy. In 3 hypothyroid patients without prior thyroid replacement, total T4 showed a change similar to patients in the control group but remained below the normal range until starting thyroid replacement therapy. Coronary bypass surgery was performed safely in patients with hypothyroidism. Preoperative thyroid replacement with suboptimal doses was safe in patients with severe hypothyroidism. Adequate postoperative thyroid replacement was achieved in all patients without complications.

Adult↗
PubMed1991

Results of surgical treatment in patients with stage IIIA non-small-cell lung cancer.

From 1973 to 1989, surgical resection was performed in 235 stage IIIA non-small-cell lung cancer patients (78% of all admitted stage IIIA patients). Complete resection was accomplished in 155 patients and 80 underwent incomplete resection. The rate of incomplete resection was higher in patients with adenocarcinoma than in those with squamous cell carcinoma. There were 7 operative deaths (2.8%) among the patients undergoing operation. The five-year survival rate of the group having complete resection was 32%, whereas that of the incomplete resection group was 5% (p less than 0.05). The five-year survival rate of T3NO-1MO patients with complete resection was 50% and that of T1-2N2MO patients was 30%. However, the five-year survival rate of patients with T3N2MO disease was significantly poorer at 10% (p less than 0.05). The five-year survival rates of patients undergoing complete resection including the combined resection of an adjacent organ were: pericardium 43%; chest wall 43%; pleura 34%; and bronchus 46%. Forty-nine patients survived over three years and 10 of them died between three and five years after surgery, but five-year, four-year, and three-year survivors numbered 29, 4, and 6, respectively. Surgical resection appears to be the treatment of choice for stage IIIA non-small-cell lung cancer whenever complete resection is feasible.

Carcinoma, Non-Small-Cell Lung↗
PubMed1991

Results of surgical treatment in patients with stage IIIB non-small-cell lung cancer.

From 1973 to March 1989, surgical resection was performed in 83 stage IIIB non-small-cell lung cancer patients (81% of all admitted stage IIIB patients). There were 2 operative deaths (2.3%), and complete resection was accomplished in 33 patients. The five-year survival rate of the patients undergoing complete resection was 25%, whereas that of the incomplete resection group was nil (p less than 0.05). Among the 26 patients with invasion of mediastinal structures who underwent complete resection, 3 patients survived for over five years. Two had squamous-cell carcinoma and one had adenocarcinoma, and their tumors involved the left atrium, pulmonary arterial trunk, and superior vena cava, respectively. Among the 6 patients with T4 lesions due to carinal invasion, two patients (one with mucoepidermoid carcinoma and one with squamous-cell carcinoma) have survived for over 8 and 4 years, respectively, after complete resection. There were no long-term survivors among the patients with malignant pleural effusion. Pleuropneumonectomy did not improve survival. Extended lymph-node dissection for N3 disease was only commenced in recent years, so it is not yet clear whether it will affect the survival rate or not. However, 6 out of 19 patients who underwent extended lymph-node dissection including the contralateral lymph-node compartments are still alive, with 23 months being the longest survival. To date, there are 6 three-year survivors among our present series of stage IIIB patients who underwent operative treatment. From these results, it can be concluded that stage IIIB patients should not be uniformly excluded from consideration for surgery, but rather should be evaluated with regard to the possibility of performing complete resection.

Carcinoma, Non-Small-Cell Lung↗
PubMed1991

Improved survival in left non-small-cell N2 lung cancer after more extensive operative procedure.

The five-year survival rate of lung-cancer patients with left-sided N2 non-small-cell disease is worse than that for those with right-sided lesions and this is partly caused by inadequate nodal dissection due to anatomical limitations. To overcome the problem of performing nodal dissection in the left mediastinum, several modifications of the operative technique have been tried in the past 18 years. The survival rates of the patients treated by each procedure were retrospectively compared in this study. The dissection method for mediastinal nodes was modified at three periods (1973-1980, 1981-1985, and 1986-1990). The first period involved less extensive node dissection, in the second period more extensive dissection was enabled by mobilization of the aortic arch, and in the most recent systematic and extensive dissection was made possible by the use of a median sternotomy. The five-year survival rates of the left-sided N2 patients undergoing complete resection in the first and second period were 8.3%, and 15.4%, respectively. The three-year survival rate in the most recent period has risen to 30.8%. Complete and extensive dissection of the mediastinal nodes after performing a median sternotomy is the procedure of choice for lung-cancer patients with left-sided N2 disease.

Adult↗
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.

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