Biomedical subjects

K R Bailey

Publications and source records attributed to K R Bailey.

At least 163 records · Page 9Linked to original sources

PubMed1992

Effect of external beam irradiation on neointimal hyperplasia after experimental coronary artery injury.

Human coronary artery restenosis after percutaneous revascularization is a response to mechanical injury. Smooth muscle cell proliferation is a major component of restenosis, resulting in obstructive neointimal hyperplasia. Because ionizing radiation inhibits cellular proliferation, this study tested in a porcine coronary injury model the hypothesis that the hyperplastic response to coronary artery injury would be attenuated by X-irradiation. Deep arterial injury was produced in 37 porcine left anterior descending coronary artery segments with overexpanded, percutaneously delivered tantalum wire coils. Three groups of pigs were irradiated with 300-kV X-rays after coil injury: Group I (n = 10), 400 cGy at 1 day; Group II (n = 10), 400 cGy at 1 day and 400 cGy at 4 days and Group III (n = 9), 800 cGy at 1 day. Eight pigs in the control group underwent identical injury but received no radiation. Treatment efficacy was histologically assessed by measuring neointimal thickness and percent area stenosis. Mean neointimal thickness in all irradiated groups was significantly higher than in the control groups and thickness was proportional to X-ray dose. X-irradiation delivered at these doses and times did not inhibit proliferative neointima. Rather, it accentuated the neointimal response to acute arterial injury and may have potentiated that injury.

Angioplasty, Balloon, Coronary↗

PubMed1992

Initial and long-term outcome of 354 patients after coronary balloon angioplasty of total coronary artery occlusions.

BACKGROUND: Coronary balloon angioplasty of chronic total occlusions is associated with relatively low success rates and a high incidence of restenosis. Whether there is long-term benefit in performing angioplasty of these lesions is unknown. The purpose of the present report was to analyze the long-term outcome of a large series of patients undergoing this procedure. METHODS AND RESULTS: A computerized database analysis of 354 consecutive patients (from 1979 to 1990) who underwent coronary angioplasty of a chronic total coronary occlusion was performed (mean age, 62.3 years). Initial technical success was achieved in 69%; in 66%, success was achieved without procedural death or need for coronary artery surgery. During hospitalization, six patients suffered myocardial infarction, nine required emergency bypass surgery, and nine patients died. During a mean follow-up period of 2.7 years, no difference was found in survival or freedom from myocardial infarction among 234 successfully dilated patients compared with 120 patients with a failed attempt. However, the use of coronary artery bypass surgery was significantly less after successful dilation (p less than 0.0001 versus failed attempt). No significant difference in the cumulative incidence of severe angina was observed between these two patient populations, with the majority remaining asymptomatic. Restenosis occurred in 59% of 69 patients who returned for follow-up angiography. CONCLUSIONS: Successful recanalization is achieved in the majority of patients undergoing angioplasty of chronic total occlusions and reduces the need for coronary artery bypass surgery. However, no major impact on either survival or incidence of myocardial infarction was noted after successful recanalization when patients with surgery were included.

Angioplasty, Balloon, Coronary↗

PubMed1992

Dynamic intraventricular obstruction during dobutamine stress echocardiography. A new observation.

BACKGROUND: The implications of hypotension occurring during dobutamine stress echocardiography have not been elucidated. We observed in some patients that hyperdynamic left ventricular function developed during dobutamine stress echocardiography and hypothesized that intracavitary obstruction was occurring and might account for hypotension in some patients. METHODS AND RESULTS: Fifty-seven consecutive patients undergoing dobutamine stress echocardiography underwent pulsed-wave and continuous-wave Doppler examination of the left ventricular cavity at rest and at peak dobutamine infusion. The development of an intraventricular gradient with dobutamine stress was defined as a late-peaking left ventricular Doppler velocity profile that exceeded basal velocity by at least 1 m/sec. During dobutamine stress testing, left ventricular outflow velocity or intracavitary velocity increased in all patients. Obstruction occurred in 12 patients (21%, group 1). Group 2 was the remaining 45 patients. Peak velocities in group 1 ranged from 2.0 to 5.0 m/sec (mean, 3.5 m/sec), and the mean increase from velocity at rest was 2.3 m/sec. The mean change in systolic blood pressure was significantly lower in patients in group 1 (-15 versus 4 mm Hg, p = 0.02). When the 18 patients with an ischemic response to stress testing (evidenced by new or worsening wall motion abnormalities) were excluded from analysis, systolic blood pressure response was still significantly different for the two groups (-19 versus 2 mm Hg, p = 0.03). CONCLUSIONS: Dynamic left ventricular obstruction is a new observation; it may develop frequently in patients undergoing dobutamine stress echocardiography. Obstruction rather than ischemia may explain a decrease in blood pressure during dobutamine stress echocardiography.

Aged↗

PubMed1991

Exercise-induced increases in atrial natriuretic factor are attenuated by endurance training.

Short-term exercise has been associated with increased plasma levels of atrial natriuretic factor, a potent dilating and natriuretic hormone. In this study, the effect of exercise training on atrial natriuretic factor release during short-term exercise was investigated in men without a history of cardiovascular or other major disease. A well trained group of 10 men who exercised an average of 6,618 kcal/week was compared with a minimally trained group of 9 men who exercised 1,479 kcal/week. Maximal oxygen uptake was 55.2 ml/kg per min in the well trained group and 42.5 ml/kg per min in the minimally trained group (p less than 0.05). Plasma for atrial natriuretic factor, norepinephrine and epinephrine was obtained at rest, at 4 min of exercise and at maximal exercise. Atrial natriuretic factor was lower at rest in the minimally trained than in the well trained men (23 vs. 35.9 pg/ml, p less than 0.05). At maximal exercise, atrial natriuretic factor increased 2.6 times the value at rest in minimally trained men (59.8 pg/ml, p less than 0.05 vs. rest), but did not change in well trained men (34 pg/ml). In minimally trained men at rest, at 4 min of exercise and at maximal exercise, plasma levels of atrial natriuretic factor correlated with heart rate, cardiac output, mean arterial pressure and plasma levels of norepinephrine and epinephrine; these correlations were not found in the well trained group. Thus, short-term exercise results in a significant increase in atrial natriuretic factor in minimally trained but not in well trained men.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Age-related characteristics of ambulatory blood pressure load and mean blood pressure in normotensive subjects.

Ambulatory blood pressure monitoring has become increasingly popular for diagnosing and treating hypertension. However, data from normotensive subjects are needed for interpretation of hypertensive readings. Ambulatory blood pressure was monitored in 126 normotensive subjects (age range, 20 to 84 years). Mean systolic and diastolic blood pressure and blood pressure loads (percentage of systolic readings greater than 140 mm Hg and diastolic readings greater than 90 mm Hg) were obtained and interpreted. Mean awake systolic and diastolic pressures ranged from 125 +/- 10 to 137 +/- 17 mm Hg and 70 +/- 8 to 71 +/- 9 mm Hg, respectively. The systolic and diastolic trends of subjects' blood pressures taken during office visits and the 24-hour measurements were similar. Ranges for systolic and diastolic blood pressure loads from youngest to oldest ages were 9% +/- 14% to 25% +/- 20% and 3% +/- 7% to 4% +/- 7%, respectively. A comparison of blood pressure means from our sample that were taken during office visits and blood pressure means from a 2122-patient community survey demonstrated that our sample was reflective of an unselected population.

Adult↗

PubMed1991

Predictors of early mortality in patients with angiographically documented left main coronary artery disease.

To determine predictors of early death after coronary angiography in patients with significant left main coronary artery disease (greater than or equal to 60% diameter narrowing, LMCAD), we reviewed the clinical records of patients with LMCAD who died after angiography. Of 1,288 patients with LMCAD studied between January 1978 and October 1989, 21 died within 2 days after angiography (group 1). As a control group, 85 patients were randomly sampled from 1,196 patients who survived at least 30 days after angiography (group 2). The predictors of early death after angiography in patients with LMCAD were older age (P less than 0.05), New York Heart Association Class III or IV (P less than 0.005), shorter duration of unstable angina (P less than 0.005), higher left ventricular end-diastolic pressure (P less than 0.006), lower ejection fraction (P less than 0.005), and significant left circumflex artery disease (P less than 0.006). The use of heparin infusion after angiography did not appear to be a significant factor. It is suggested that earlier operation or more aggressive management be undertaken in patients who, at cardiac catheterization, have significant LMCAD associated with the above-listed variables.

Aged↗

PubMed1991

Consequences of restenosis after coronary angioplasty.

The consequences of restenosis after angioplasty were evaluated in 466 patients who had coronary angiography 3 to 12 months after successful coronary angioplasty and were followed long term. The 236 subjects with restenosis resembled the 230 without restenosis with respect to age, sex, presence of multivessel disease, mean ejection fraction, prior myocardial infarction, prior coronary artery bypass grafting, and completeness of revascularization. The 5-year relative risk of revascularization for patients with restenosis markedly exceeded that for patients without restenosis. The relative risk of repeat angioplasty in the former group was 4.26 times that in the latter group (95% confidence interval, 2.80 to 6.51), and the risk of coronary artery bypass grafting in patients with restenosis was 3.68 (95% confidence interval, 2.16 to 6.28). There was no difference between the 2 groups in the relative risk of myocardial infarction or death. When the completeness of revascularization was considered, patients with incomplete revascularization and restenosis had the worst outcomes, with 50% needing coronary artery bypass grafting within 5 years. Early restenosis markedly increases the probability of revascularization, but it has little effect on infarction or mortality. Even when early restenosis is absent, further revascularization procedures are still frequent. A solution to the problem of restenosis might reduce by half the need for revascularization during the subsequent 5 years.

Angioplasty, Balloon, Coronary↗

PubMed1991

Detecting fabrication of data in a multicenter collaborative animal study.

In 1980-1981 the National Heart, Lung, and Blood Institute (NHLBI) sponsored a multicenter study of animal models for protection of ischemic myocardium (AMPIM). After data collection for the study was complete, problems were identified with data from one of the labs. This article deals with the issue of statistical evidence versus hard evidence as well as the process of crossing the boundary from suspicion to certainty regarding the nature and extent of the problem.

Animals↗

PubMed1991

Electrocardiographic prediction of myocardial area at risk.

The 12-lead electrocardiogram in 23 patients with an evolving first myocardial infarction (12 anterior and 11 inferior) was correlated with the myocardial area at risk measured by tomographic perfusion imaging with technetium-99m sestamibi. Of several electrocardiographic factors, only the extent and quantity (with and without R-wave normalization) of ST depression differed significantly between inferior and anterior evolving infarction. The myocardial area at risk was greater in anterior than in inferior evolving infarction. The extent of the myocardium at risk correlated modestly (r = 0.58) with total ST displacement in anterior evolving infarction and with total ST depression normalized to the R wave (r = 0.70) in inferior evolving infarction. Because of the large standard errors (9 to 15% of the left ventricle), estimates of the myocardial area at risk based on these electrocardiographic variables have minimal clinical value in the individual patient.

Electrocardiography↗

PubMed1991

Natural history of moderate aortic stenosis.

The natural history of severe, symptomatic aortic stenosis has been well documented. However, the natural history of moderate aortic stenosis remains poorly understood. Therefore, a group of 66 patients was identified who had a diagnosis of moderate aortic stenosis at the time of cardiac catheterization (aortic valve area 0.7 to 1.2 cm2) and who did not have surgical therapy during the 1st 180 days after cardiac catheterization. During a mean follow-up period of 35 months, 14 patients died of causes attributed to aortic stenosis and 21 underwent aortic valve replacement. The estimated probability for remaining free of any complication of aortic stenosis at the end of the first 4 years was 59%. Symptomatic patients with decreased ejection fraction or hemodynamic evidence of left ventricular decompensation were at greater risk for these complications. It is concluded that patients with moderate aortic stenosis are at significant risk for the development of complications.

Aged↗

PubMed1991

Late potentials on signal-averaged electrocardiograms and patency of the infarct-related artery in survivors of acute myocardial infarction.

This study evaluated the relation between patency of the infarct-related artery and the presence of late potentials on the signal-averaged electrocardiogram (ECG) in 124 consecutive patients (98 men, 26 women; mean age 59 years) with acute myocardial infarction receiving thrombolytic therapy, acute percutaneous transluminal coronary angioplasty or standard care. All patients were studied by coronary angiography, measurement of ejection fraction and signal-averaged ECG. The infarct-related artery was closed in 51 patients and open in 73. Among patients with no prior myocardial infarction undergoing early attempted reperfusion therapy, a patent artery was associated with a decreased incidence of late potentials (20% versus 71%; no significant difference in ejection fraction). In the 48 patients receiving thrombolytic agents within 4 h of symptom onset, the incidence of late potentials was 24% and 83% among patients with an open or closed artery, respectively (p less than 0.04). The most powerful predictors of late potentials were the presence of a closed infarct-related artery, followed by prior infarction and patient age. Among patients receiving thrombolytic agents within 4 h of symptom onset, the only variable that was predictive of the presence of late potentials was a closed infarct-related artery. These data imply that reperfusion of an infarct-related artery has a beneficial effect on the electrophysiologic substrate for serious ventricular arrhythmias that is independent of change in left ventricular ejection fraction as an index of infarct size. These findings might explain, in part, the low late mortality rate in survivors of myocardial infarction with documented reperfusion of the infarct-related artery.

Angioplasty, Balloon, Coronary↗

PubMed1991

Percutaneous transluminal coronary angioplasty in the elderly: early and long-term results.

The immediate and long-term efficacy of coronary angioplasty in the elderly was determined by studying 752 patients greater than or equal to 65 years old and comparing patients greater than or equal to 75 years old with those 65 to 74 years old. The oldest patients were more highly symptomatic, were more likely to be in heart failure, had more multivessel disease and were more likely to undergo multivessel dilation. The immediate success rate of angioplasty was higher in the oldest patients (92.8% versus 82%) (p = 0.0003). The hospital mortality rate was also higher (6.2% versus 1.6%) (p less than 0.001). Long-term overall survival was high. However, long-term event-free survival was lowest in the oldest patients, and recurrent severe angina was particularly common. Thus, in very elderly patients, coronary angioplasty is usually successful, but extra caution is warranted; also, long-term relief from angina is less common than in younger patients.

Aged↗

PubMed1991

Prognostic significance of Doppler measures of diastolic function in cardiac amyloidosis. A Doppler echocardiography study.

BACKGROUND: We have previously characterized the left ventricular diastolic filling abnormalities in cardiac amyloidosis by Doppler methods. The various filling patterns were shown to be related to the degree of cardiac amyloid infiltration. The purpose of this study was to determine the value of Doppler diastolic filling variables for assessing prognosis in cardiac amyloidosis. METHODS AND RESULTS: We performed pulsed-wave Doppler studies of the left ventricular inflow and obtained clinical follow-up data in 63 consecutive patients with biopsy-proven systemic amyloidosis. All patients had typical echocardiographic features of cardiac involvement. The patients were subdivided into two groups according to deceleration time: Group 1 (33 patients) had a deceleration time of 150 msec or less, indicative of restrictive physiology, and group 2 (30 patients) had a deceleration time of more than 150 msec. Of the 63 patients, 32 (51%) died during a mean follow-up period of 18 +/- 12 months. Of these deaths, 25 (78%) were cardiac deaths, and 19 of the 25 patients (76%) were from group 1. The 1-year probability of survival in group 1 was significantly less than that in group 2 (49% versus 92%, p less than 0.001). Bivariate analysis revealed that the combination of the Doppler variables of shortened deceleration time and increased early diastolic filling velocity to atrial filling velocity ratio were stronger predictors of cardiac death than were the two-dimensional echocardiographic variables of mean left ventricular wall thickness and fractional shortening. CONCLUSIONS: Doppler-derived left ventricular diastolic filling variables are important predictors of survival in cardiac amyloidosis.

Amyloidosis↗

PubMed1991

Catecholamine metabolic pathways and exercise training. Plasma and urine catecholamines, metabolic enzymes, and chromogranin-A.

BACKGROUND: Because acute exercise increases systemic catecholamines, we sought to determine whether exercise training would alter daily or exercise-related catecholamine release and inactivation. METHODS AND RESULTS: In 24-hour urine collections, catecholamines and metabolites provided indexes of overall oxidative deamination, sulfation, and O-methylation. Plasma catecholamines, the sulfoconjugates of each, and chromogranin-A were determined at rest and during exercise in 10 well-trained male subjects and nine minimally trained male subjects (maximal oxygen uptake 55.2 and 42.5 ml/kg/min, respectively), and levels of activities of catechol-O-methyltransferase (COMT), monoamine oxidase B (MAO-B), and thermolabile phenolsulfotransferase (TL-PST) were also determined. Plasma-free catecholamines showed minimal differences between the two groups at submaximal exercise (4 minutes) but large differences at maximal exercise, reflecting the different exercise levels attained. Inactivation of plasma catecholamines by sulfation across rest and exercise tended to be greater in the well-trained group, with small increases in both plasma sulfoconjugated dopamine and sulfoconjugated norepinephrine. In the well-trained group, urinary metabolites demonstrated trends toward increased dopamine release (p less than 0.07) and small increases in the daily release of epinephrine and its sulfoconjugated metabolites. Indexes of deamination, sulfoconjugation, and O-methylation, with the exception of a reduced deamination of dopamine and the activities of COMT, MAO-B, and TL-PST were not different in the two groups. CONCLUSIONS: Despite considerable differences in the exercise activities per week between well-trained and minimally trained individuals, there were minimal differences in the release and metabolism of catecholamines at rest or during exercise.

Adult↗

PubMed1990

Influence of ventricular function and presence or absence of coronary artery disease on results of electrophysiologic testing for asymptomatic nonsustained ventricular tachycardia.

One hundred ten patients with asymptomatic nonsustained ventricular tachycardia (VT) were evaluated prospectively to assess the value of electrophysiologic testing. This testing consisted of up to 3 extrastimuli delivered during 3 drive cycle lengths from 2 right ventricular sites. A positive study was defined as monomorphic VT lasting 30 seconds or requiring cardioversion. Patients with a positive study were treated, and serial drug testing was done. An event during follow-up was sustained VT or cardiac arrest. The mean follow-up was 15 months. Of 57 patients with an ejection fraction greater than or equal to 40%, 6 had a positive electrophysiologic test with 1 event and 51 had a negative test with 1 event. Twenty-eight patients had an ejection fraction less than 40% and coronary artery disease: 14 had a positive test with 1 event, and 14 had a negative test with 3 events. Twenty-five patients had an ejection fraction less than 40% and no coronary artery disease: 1 had a positive test with no events, and 24 had a negative test with 8 events. Only ejection fraction and congestive heart failure class were found to be independent predictors of outcome. Patients with an ejection fraction greater than 40% had low inducibility (11%), had few events (3.5%) and did not require electrophysiologic testing. In patients with an ejection fraction less than 40% and coronary artery disease, inducibility was high (50%) and a negative study was of no value. Patients with an ejection fraction less than 40% and no coronary artery disease had low inducibility (4%), had frequent events (33%) and did not benefit from electrophysiologic testing.

Adult↗

PubMed1990

Comprehensive Doppler assessment of right ventricular diastolic function in cardiac amyloidosis.

To assess right ventricular diastolic function in cardiac amyloidosis, pulsed wave Doppler ultrasound measurements of right ventricular inflow velocities and superior vena cava and hepatic vein flow velocities with respiratory monitoring were performed in 41 patients with primary systemic amyloidosis and two-dimensional echocardiographic features of cardiac involvement. Right ventricular diastolic function was abnormal in 31 (76%) of these patients, the major abnormality being a short deceleration time (less than 150 ms) in 21 (68%), suggesting restriction. In contrast, 7 (23%) of the 31 patients had a decreased ratio of early (E) and late (A) diastolic peak flow velocities and a prolonged deceleration time (greater than 240 ms), suggesting abnormal relaxation. The patients were classified into two groups on the basis of right ventricular free wall thickness: group 1, less than 7 mm and group 2, greater than or equal to 7 mm. Compared with normal values, group 1 showed an increased peak late flow velocity (44 +/- 19 versus 39 +/- 6 cm/s; p less than 0.01) and a decreased E/A velocity ratio (1.1 +/- 0.4 versus 1.5 +/- 0.3; p less than 0.01). Group 2 showed a markedly shortened deceleration time (151 +/- 37 versus 225 +/- 28 ms; p less than 0.01), characteristic of restriction. In the overall group, superior vena cava peak flow velocity was decreased in systole and increased in diastole and flow reversals during inspiration were increased compared with normal values. Hepatic venous flow velocities were similar to those in the superior vena cava except for larger flow reversals in the hepatic vein. Thus, in cardiac amyloidosis, right ventricular diastolic function is abnormal. There is a spectrum of right ventricular filling abnormalities and the restrictive filling pattern is seen only in the advanced stages of the disease.

Amyloidosis↗

PubMed1990

The natural history of adults with asymptomatic, hemodynamically significant aortic stenosis.

The natural history of asymptomatic, hemodynamically significant, valvular aortic stenosis in adults was documented. Of 471 patients with aortic stenosis identified by Doppler echocardiography (peak systolic flow velocity greater than or equal to 4 m/s) from January 1984 through August 1987, 143 were asymptomatic and had isolated valvular aortic stenosis. Thirty patients underwent aortic valve intervention within 3 months (group 1); the remaining 113 patients did not have an intervention within 3 months (group 2). Follow-up information was available for all patients; the mean duration of follow-up study was 20 months (range 6 to 48). Three cardiac events occurred in the 30 group 1 patients after operation (two deaths, one reoperation). Among the 113 group 2 patients, three had cardiac death presumed to be a result of the aortic stenosis; all three developed symptoms at least 3 months before death. The actuarial probability of remaining free of symptoms of angina, dyspnea or syncope for group 2 was 86% at 1 year and 62% at 2 years. For this group, the 1 and 2 year probabilities of remaining free of cardiac events, including aortic valve intervention or cardiac death, were 93% and 74%, respectively. Of all clinical and echocardiographic variables (group 2), only Doppler flow velocity (p = 0.004) and ejection fraction (p = 0.01) were independent predictors of subsequent cardiac events. Among the 44 patients (groups 1 and 2) with a flow velocity greater than or equal to 4.5 m/s, the relative risk of sustaining a cardiac event (by Cox regression analysis) was 4.9 (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Percutaneous transluminal angioplasty in patients with multivessel coronary disease: how important is complete revascularization for cardiac event-free survival?

The relative influences of revascularization status and baseline characteristics on long-term outcome were examined in 867 patients with multivessel coronary disease who had undergone successful coronary angioplasty. These patients represented 83% of a total of 1,039 patients in whom angioplasty had been attempted with an in-hospital mortality and infarction rate of 2.5% and 4.8%, respectively. Emergency coronary bypass surgery was needed in 4.9%. Of the 867 patients, 41% (group 1) were considered to have complete revascularization and 59% (group 2) to have incomplete revascularization. Univariate analysis revealed major differences between these two groups with patients in group 2 characterized by advanced age, more severe angina, a greater likelihood of previous coronary surgery and infarction, more extensive disease and poorer left ventricular function. Over a mean follow-up period of 26 months, the probability of event-free survival was significantly lower for group 2 only with respect to the need for coronary artery surgery (p = 0.004) and occurrence of severe angina (p = 0.04). The difference in mortality was of borderline significance (p = 0.051) and there were no significant differences between groups 1 and 2 in either the incidence of myocardial infarction or the need for repeat angioplasty. Multivariate analysis identified independent baseline predictors of late cardiac events that were then used to adjust the probabilities of event-free survival. This adjustment effectively removed any significant influence of completeness of revascularization on event-free survival for any of the above end points including the combination of death, myocardial infarction and need for coronary artery surgery. Therefore, late outcome in these patients is not significantly influenced by revascularization status but depends more on baseline patient characteristics.

Age Factors↗