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Biomedical subjects

T Takaro

Publications and source records attributed to T Takaro.

At least 19 recordsLinked to original sources
PubMed1994

Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration.

We carried out a systematic overview using individual patient data from the seven randomised trials that have compared a strategy of initial coronary artery bypass graft (CABG) surgery with one of initial medical therapy to assess the effects on mortality in patients with stable coronary heart disease (stable angina not severe enough to necessitate surgery on grounds of symptoms alone, or myocardial infarction). 1324 patients were assigned CABG surgery and 1325 medical management between 1972 and 1984. The proportion of patients in the medical treatment group who had undergone CABG surgery was 25% at 5 years, 33% at 7 years, and 41% at 10 years: 93.7% of patients assigned to the surgery group underwent CABG surgery. The CABG group had significantly lower mortality than the medical treatment group at 5 years (10.2 vs 15.8%; odds ratio 0.61 [95% CI 0.48-0.77], p = 0.0001), 7 years (15.8 vs 21.7%; 0.68 [0.56-0.83], p < 0.001), and 10 years (26.4 vs 30.5%; 0.83 [0.70-0.98]; p = 0.03). The risk reduction was greater in patients with left main artery disease than in those with disease in three vessels or one or two vessels (odds ratios at 5 years 0.32, 0.58, and 0.77, respectively). Although relative risk reductions in subgroups defined by other baseline characteristics were similar, the absolute benefits of CABG surgery were most pronounced in patients in the highest risk categories. This effect was most evident when several prognostically important clinical and angiographic risk factors were integrated to stratify patients by risk levels and the extension of survival at 10 years was examined (change in survival -1.1 [SE 3.1] months in low-risk group, 5.0 [4.2] months in moderate-risk group, and 8.8 [5.4] months in high-risk group; p for trend < 0.003). A strategy of initial CABG surgery is associated with lower mortality than one of medical management with delayed surgery if necessary, especially in high-risk and medium-risk patients with stable coronary heart disease. In low-risk patients, the limited data show a non-significant trend towards greater mortality with CABG.

Adult↗
PubMed1991

Ten-year incidence of myocardial infarction and prognosis after infarction. Department of Veterans Affairs Cooperative Study of Coronary Artery Bypass Surgery.

BACKGROUND: The 10-year incidence of myocardial infarction (fatal and nonfatal) and the prognosis after infarction were evaluated in 686 patients with stable angina who were randomly assigned to medical or surgical treatment in the Veterans Administration Cooperative Study of Coronary Artery Bypass Surgery. METHODS AND RESULTS: Myocardial infarction was defined by either new Q wave findings or clinical symptoms compatible with myocardial infarction accompanied by serum enzyme elevations with or without electrocardiographic findings. Treatment comparisons were made according to original treatment assignment; 35% of the medical cohort had bypass surgery during the 10-year follow-up period. The overall cumulative infarction rate was somewhat higher in patients assigned to surgery (36%) than in medical patients (31%) (p = 0.13) due to perioperative infarctions (13%) and an accelerated infarction rate after the fifth year of follow-up (average, 2.4%/yr in the surgical group versus 1.4%/yr in the medical group). The 10-year cumulative incidence of death or myocardial infarction was also higher in surgical (54%) than in medical (49%) patients (p = 0.20). According to the Cox model, the estimated risk of death after infarction was 59% lower in surgical than in medical patients (p less than 0.0001). The reduction in postinfarction mortality with surgery was most striking in the first month after the event: 99% in the first month (p less than 0.0001) and 49% subsequently (p less than 0.0001). The estimated risk of death in the absence of infarction was nearly identical regardless of treatment (p = 0.75). Exclusion of perioperative infarctions did not alter the findings. CONCLUSIONS: Although surgery does not reduce the incidence of myocardial infarction overall, it does reduce the risk of mortality after infarction, particularly in the first 30 days after the event (fatal infarctions).

Angina Pectoris↗
PubMed1990

Acute and subacute effects of injury on the canine alveolar septum.

The effect of papain on the prevalence and distribution of alveolar macrophages, alveolar septal interstitial tissue gaps and epithelial cells in normal canine pulmonary alveoli was studied by light and electron microscopy. Serial sections of whole alveoli from control animals and from animals sacrificed 4 h, two weeks and one month after the instillation into one lung of crude papain in saline solution containing India ink as a marker were compared. In dogs, as in humans, there is normally a zonal distribution of alveolar macrophages and type 2 cells at alveolar junctional sites. We hypothesize that early alveolar septal injury takes place at these junctional sites, judging from concentration of alveolar macrophages and interstitial septal gaps at these sites following papain exposure, and also that septal repair activities are greatest at these sites, in view of the preponderance and high prevalence of type 2 cells occupying interstitial septal gaps in junctional zones. Consequently, the type 2 cell may play a role beyond that of merely replacing type 1 epithelial cells following alveolar septal injury.

Acute Disease↗
PubMed1988

Five-year changes in coronary arteries of medical and surgical patients of the Veterans Administration Randomized Study of Bypass Surgery.

Progression of coronary artery disease was evaluated after 5 years of follow-up in 119 medically and 109 surgically treated randomized patients who adhered to their assigned therapy. Progression was defined as the appearance of a new lesion (greater than or equal to 50% stenosis) or worsening of a preexisting lesion in a coronary artery. Progression occurred in 36% (97 of 268) of the arteries in medical patients, in 38% (35 of 93) of the ungrafted arteries in surgical patients, in 74% (72 of 97) of the arteries with patent grafts at 5 years, and in 63% (29 of 46) of the arteries with closed grafts. After adjustment for the vessel system and the severity of disease at baseline, the risk of progression was three to six times higher in grafted arteries than in ungrafted arteries (p less than 0.01). For grafted arteries, the risk of progression was twice as high in arteries with patent grafts compared with those with closed grafts (p = 0.14). The majority (78%) of the progression in grafted arteries was to 100% occlusion. Proximal and distal progression rates in arteries with patent grafts were 74% and 11%, respectively. In the majority of arteries with closed grafts that progressed, the site of progression could not be determined. Regardless of treatment, the risk of progression was two times higher in the right coronary artery than in the left anterior descending or circumflex arteries. Progression risk was also twice as high in arteries with moderate disease at baseline compared with those with minimal or severe disease.

Coronary Angiography↗
PubMed1986

Quality control for cardiac surgery in the Veterans Administration.

The volume of cardiac surgical procedures and the 30-day mortality associated with them were reviewed for the total experience of 72 Veterans Administration medical centers over a 10-year period (1975 to 1984). The total number of cardiopulmonary bypass operations increased from 3,074 in 1975 to 6,455 in 1984, whereas operative mortality declined from 8.3 to 4.7%. Operative mortality associated with isolated valve replacement operations declined from 10.9 to 5.9%. Aortocoronary vein bypass operations, which increased in number from 1,679 to 4,988 over the 10-year period, were associated with an operative mortality of 4.7% in 1975 and 3.6% in 1984. The extent of the patient's disease accounted for most of the operative mortality, but problems related to the adequacy of myocardial protection and the surgical technique were also important factors. These data were compared with similar comprehensive statistics compiled by the New York State Department of Health over a five-year period (1979-1983). Operative mortality rates were quite similar for aortocoronary bypass procedures, mitral valve replacements, and total cardiac operations. However, operative mortality for aortic valve procedures was higher among the Veterans Administration hospitals. In the future, if operative risk factors are clearly defined, a more meaningful comparison of operative mortality among ongoing reviews, such as those being carried out by the Veterans Administration and by New York State, could be used to establish standards of performance for cardiac surgery.

Aortic Valve↗
PubMed1986

Zonal distribution of alveolar macrophages, type II pneumonocytes, and alveolar septal connective tissue gaps in adult human lungs.

The distribution of alveolar macrophages, Type II cells, and alveolar septal connective tissue discontinuities or gaps in two neighboring alveoli from a human lung obtained at surgery, and preserved by vascular perfusion-fixation, was studied by electron microscopy. Discontinuities or gaps are defined as complete interruptions of all the connective tissue elements of the alveolar septum, including the basement membranes. Serial-sectioning of the alveoli, and the creation of montages of the entire circumference of each alveolus at intervals of every twentieth section (approximately 1.6 micron) at a magnification of X 2,160 permitted precise identification of cells and connective tissue gaps and allowed the reconstruction, by computer techniques, of the alveolar walls in 3 dimensions. These studies showed that all of the 48 alveolar macrophages identified, and over two thirds of all Type II cells and alveolar septal gaps, were located or bordered on alveolar septal junctional zones (within 10 microns of septal junctions). The profiles of 739 alveoli examined by light microscopy from 6 lungs similarly preserved by vascular perfusion-fixation, in which the alveolar surface lining was well fixed, also showed alveolar macrophages preferentially distributed in alveolar junctional zones. These were compared with 242 alveolar profiles from 3 other vascularly-fixed lungs and 971 alveolar profiles from 9 lungs fixed by way of the airways, in which the alveolar surface lining was lost. In these lungs, most of the alveolar macrophages were in the alveolar air spaces.(ABSTRACT TRUNCATED AT 250 WORDS)

Connective Tissue Cells↗
PubMed1985

Anatomical relationships between type II pneumonocytes and alveolar septal gaps in the human lung.

This report describes a relationship between type II pneumonocytes and breaks in continuity in the alveolar septum of the human lung. Breaks in continuity of the septum are defined as gaps in the connective tissue matrix of the alveolar septum, with or without discontinuity of the accompanying alveolar epithelium. Septal connective tissue gaps accompanied by epithelial discontinuity are recognized as interalveolar pores of Kohn. When the discontinuity is confined to the connective tissue matrix, epithelial continuity may be maintained by either a single or a double layer of type I epithelium, by a type II cell, or by both type I and type II epithelial cells. Alveolar septal gaps were studied by electron microscopy on random sections in 26 adult human lung specimens and by serially sectioning and montaging the entire circumference of one alveolus to a depth of 103 microns (approximately one-half a normal alveolus) from one of the specimens. Fixation was by way of the airways in most specimens, but by vascular perfusion in the serially sectioned specimen and in seven others. In lungs studied by random sections, we found that the incidence of septal connective tissue gaps with epithelial continuity per specimen correlated with the incidence of pores (r = .468, P less than .016), and also with the incidence of type II cells (r = .422, P less than .025) in the specimen. Five percent of all type II cells observed in the random sections in the 26 specimens (103/1,955) occupied septal gaps, and 2.5% (49/1,955) were located at the rim of a pore. In contrast, in the single serially sectioned montaged alveolus, 69% of all type II cells occupied some type of septal gap, with 24% of all type II cells forming part of the rim of a pore. Over half of all pores in this alveolus were associated with a type II cell. We concluded that a relationship between the incidence of type II cells and gaps in the alveolar septum could be demonstrated on random sections in normal human lungs, which was much more obvious in a single serially sectioned hemialveolus. Serial section techniques of whole alveoli may be necessary to establish relationships that may not be apparent on random sections and that require the study of whole cells in continuity with their environment in order to be identified. The findings may be significant in suggesting a possible role of the type II cell in alveolar septal repair.

Adult↗
PubMed1985

The 5 year effect of bypass surgery on relief of angina and exercise performance.

The 5 year effect of medical vs surgical treatment on symptoms and exercise performance was evaluated in patients with stable angina who entered the Veterans Administration Cooperative Study from 1972 to 1974. Severity of angina was evaluated by a physician-administered angina questionnaire and physical working capacity was assessed by exercise testing. Angina was substantially relieved in surgical patients at 1 year, with 78% having mild or no angina compared with only 28% at entry. The corresponding rates in medical patients showed little change: 38% at 1 year and 32% at entry. At 5 years the percentage of surgical patients with mild or absent angina decreased from the 1 year rate of 78% to 64%, whereas the medical group exhibited a small increase from 38% to 49%. Similar results were obtained by evaluating changes in angina compared to entry. At 1 year 49% of surgical patients were markedly improved compared with only 12% of medical patients. At 5 years the percentage of surgical patients who remained markedly improved decreased to 41%, whereas the medical group with marked improvement increased slightly from 12% at 1 year to 17% at 5 years. Medication requirements were markedly reduced in surgical patients with only a slight increase in medical patients. Exclusion of nonadherers from the analysis did not change the results. Exercise testing revealed comparable changes in physical performance. At 1 year surgical patients had fewer tests stopped by angina compared with medical patients (28% vs 64%), a higher estimated oxygen consumption (26 vs 21 ml/kg/min) and treadmill exercise duration (7.3 vs 4.9 min). Other measures of exercise performance were comparably improved.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1985

Long-term mortality and morbidity results of the Veterans Administration randomized trial of coronary artery bypass surgery.

The long-term effect of coronary artery bypass grafting on mortality and the incidence of nonfatal myocardial infarction was evaluated in 686 patients in the randomized Veterans Administration study of medical vs surgical treatment for stable angina. Average follow-up was 11.2 years. The 11 year cumulative mortality rates for all patients and for the 595 patients without left main diseases were not significantly different in the two treatment groups. The 7 year mortality rates were 30% in medically assigned and 23% in surgically assigned patients (p = .043) and the 11 year rates were 43% and 42% (p = .45), respectively. The rates in patients without left main disease were 28% for medical and 23% for surgical treatment policy at 7 years (p = .267) and rose to 42% in both groups at 11 years (p = .813). A statistically significant reduction in mortality with surgical policy was found both at 7 and 11 years in high-risk patients without left main disease who had multiple clinical or angiographic risk factors or both. In the subgroup with angiographic high risk, the 7 year mortality rates were 48% in medically assigned and 24% in surgically assigned patients (p = .002); the 11 year rates were 62% and 50%, respectively (p = .026). Corresponding rates in the clinically defined high-risk group were 48% vs 28% (p = .003) at 7 years and 64% vs 51% (p = .015) at 11 years for medical vs surgical policy, respectively. For the subgroup of patients with combined angiographic and clinical high risk, the 7 year mortality rates were 64% for medical and 24% for surgical policy (p = .002); the 11 year rates were 76% and 46%, respectively (p = .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1984

Five-year effect of medical and surgical therapy on resting left ventricular function in stable angina: Veterans Administration Cooperative Study.

The effect of coronary artery bypass grafting (CABG) and medical therapy on 5-year resting left ventricular (LV) function was studied in 194 randomized patients with stable angina in the Veterans Administration Study of Coronary Artery Bypass Surgery. LV ejection fraction (EF) was determined in a central laboratory. The 92 medical and 102 surgical patients were comparable at entry with respect to historic, angiographic and electrocardiographic prognostic indicators. Twenty-eight percent of the medical and 30% of the surgical patients had a baseline EF of less than 50%. There was no significant change in mean EF between baseline and 5-year values in either treatment group. The baseline and 5-year values were 56 and 58% in each treatment group. Intervening myocardial infarction (MI) had an adverse effect in medically treated patients (59 to 46%, p less than 0.01) and in surgically treated patients with late MI (58 to 47%, difference not significant). Perioperative MI was not associated with a decrease in EF (56 to 58%, difference not significant). These findings extend the similar results of previous short-term studies of the effect of coronary bypass surgery on resting LV function to 5 years, and provide data in a comparable medical control group.

Angina Pectoris↗
PubMed1984

Characteristics and outcome of medical nonadherers in the Veterans Administration Cooperative Study of Coronary Artery Surgery.

During a 7-year follow-up period in the Veterans Administration Study of Bypass Surgery, 75 (24%) of 311 medically assigned patients without left main disease "crossed over" to surgical treatment. Nineteen baseline, clinical, electrocardiographic and angiographic characteristics of the 75 crossover patients were compared with those of the 236 patients who adhered to medical treatment. At entry into the study, the crossover group contained more patients with severe angina than did the medical adherers group (p less than 0.05) and fewer patients with electrocardiographic evidence of previous myocardial infarction (p less than 0.05). Other entry characteristics were similar in distribution among those in the medical-adherer and crossover groups. The 2 major reasons for crossover were persistence or progression of angina, which occurred in 43 and 37% of the 75 crossover patients, respectively. There was no relation between progression of symptoms and angiographic progression of coronary narrowing. Thus, crossover was not determined by more severe coronary narrowing, but was associated with more severe symptoms and a lower incidence of infarction. The medically randomized patients who later underwent surgery (medical "nonadherers") experienced the same relief of angina 1 year after surgery as did the surgically randomized patients who initially received surgery (surgical "adherers"); however, their overall 7-year survival was lower (77% for medical nonadherers vs 83% for surgical adherers; difference not significant).

Clinical Trials as Topic↗
PubMed1984

Use of staplers in pulmonary surgery.

Stapling devices have helped reduce the incidence of bronchopleural fistulas after pulmonary resection. They have also simplified the resection of lung parenchyma and the closure of large-caliber blood vessels in the hilum of the lung.

Animals↗
PubMed1982

The Veterans Administration Cooperative Study of stable angina: current status.

The current status of the Veterans Administration Cooperative Study of the effect of surgery on survival in patients with stable angina is presented. The outcome in 686 adult males randomly allocated to medical or surgical treatment groups in 1972-1974 was studied in subgroups of patients classified by invasive (arteriographic) and noninvasive risk factors. In 91 patients with left main lesions reducing the luminal diameter 50% or more, surgery significantly improved survival in the two-thirds characterized as middle or high risk by four simple noninvasive predictors of prognosis (New York Heart Association functional classification III or IV, history of myocardial infarction, history of hypertension, and ST-segment depression on the resting baseline ECG as assessed on a centralized reading). Patients with three-vessel disease and no significant disease of the left main coronary artery also had better survival rates when treated surgically. However, this was statistically significant at 6 years only in the 10 hospitals in which the aggregate operative mortality was 3.3%. Patients without left main lesions were also categorized by four noninvasive predictors of risk. Categorizing such patients into roughly equal groups of high, middle, and low risk identified a high-risk group, in which surgery was associated with statistically improved survival, and low- and middle-risk groups in which it was not. The use of both invasive and noninvasive factors to assess risk in patients with chronic stable angina pectoris provided greater predictive power than either angiography or noninvasive factors alone.

Angina Pectoris↗
PubMed1982

Survival in subgroups of patients with left main coronary artery disease. Veterans Administration Cooperative Study of Surgery for Coronary Arterial Occlusive Disease.

This report presents the 42-month survival experience of 91 patients with a significant lesion of the left main coronary artery in the Veterans Administration Cooperative Study of Coronary Bypass Surgery. Survival in surgical patients was significantly better than that in the medical group (p = 0.016), even after adjustments were made for two important differences in baseline characteristics--duration of angina and high risk by angiographic criteria--between the two groups (p = 0.019). Subgroups based on severity of left main stenosis and on left ventricular (LV) function showed significant trends in favor of surgery in patients with more than 75% left main stenosis and in those with abnormal LV function. A similar but nonsignificant trend was seen in the two subgroups with 50-75% stenosis or with normal LV function. The surgical benefits were not significantly different between the categories of the subgroups defined separately by stenosis and LV function. Low-, middle- and high-risk subgroups based on four noninvasive clinical predictors also showed significantly improved survival with surgery in the high-risk group. The low-risk groups showed a slight, nonsignificant disadvantage with surgical treatment. These data support the view that patients with left main disease are not a homogeneous group. High- and low-risk subgroups with different outcomes and responses to treatment can be delineated by angiographic or clinical criteria. For most patients with left main disease, coronary artery bypass grafting offers improved longevity.

Adult↗
PubMed1982

Thin alveolar epithelial partitions across connective tissue gaps in the alveolar wall of the human lung: ultrastructural observations.

We describe sharply localized attenuated areas in the alveolar walls of 17 of 25 human specimens. In these areas the connective tissue scaffolding of the alveolar septum was interrupted, and the thickness of the alveolar wall was reduced to that of a single or double layer of alveolar epithelium, devoid of basal laminae. Serial sections proved that most such gaps were bridged by a thin partition of intact epithelium continuous with Type I cells at the borders of the gap. These areas were observed infrequently during a systematic ultrastructural survey of specimens from grossly normal areas of lung tissue obtained at surgery or at autopsy. The mean diameter of 25 gaps bridged by a double layer of epithelium was 4.1 +/- 2.0 micrometers, whereas that of 49 gaps bridged by a single layer of epithelium was 5.0 +/- 1.9 micrometers. This contrasted with the mean diameter of 329 interalveolar pores, which was 6.5 +/- 2.4 micrometers (p less than 0.01). The number of profiles of epithelial partitions per centimeter of section profiles of interalveolar septums examined correlated directly with the number of pore profiles (p less than 0.003). This correlation, and the stepwise increase in size of gaps beginning with those bridged by 2 layers of epithelium and moving to those with only a single layer and finally to interalveolar pores, suggests that the epithelium-covered gaps are a transitional stage in the development of pores. This hypothesis is strengthened by the rare occurrence of epithelium-covered gaps in which the epithelial partition is itself interrupted.

Adult↗
PubMed1981

Effect of bypass surgery on survival in patients in low- and high-risk subgroups delineated by the use of simple clinical variables.

A multivariate risk function was developed on data from all 508 medical patients in the Veterans Administration (VA) randomized study of coronary bypass surgery. The variables, in order of importance, were ST-segment depression on resting ECG, history of myocardial infarction, history of hypertension and New York Heart Association functional classification III or IV. These noninvasive variables have been reported to be risk factors in natural-history studies of coronary heart disease (CHD). Applying the risk function to medical and surgical patients of the 1972-1974 cohort yielded a 5-year probability of dying for each patient. Investigation of treatment effects in approximate terciles obtained by collapsing the probability distribution into low-, middle- and high-risk groups showed that surgery was beneficial for patients in the high-risk tercile even after removal of patients with left main coronary artery disease (17% surgical vs 34% medical mortality at 5 years; p less than 0.01). This finding was accentuated when patients in the 10 hospitals with the lowest operative mortality (3.3%) were compared. Mortality results in the low-risk tercile favored medical treatment (medical vs surgical mortality 7% vs 17%; p less than 0.05). The risk function predicted mortality well not only for te VA medical group, but also for an independent symptomatic CHD population from the University of Alabama arteriography registry. This report further delineates the advantages and limitations of coronary bypass surgery in CHD patients with chronic stable angina.

Coronary Artery Bypass↗