Search PubMed⌕ Search

Biomedical subjects

G J Balady

Publications and source records attributed to G J Balady.

At least 55 records · Page 3Linked to original sources
PubMed1992

Comparison of ischemic and physiologic responses during exercise tests in men using the standard and modified Bruce protocols.

The importance of low-level (warm-up) exercise for reducing exercise-induced myocardial ischemic symptoms in patients with coronary artery disease is well-recognized by clinicians. Whether altering the abruptness of exercise, such as that which occurs during different frequently used testing protocols, affects myocardial ischemic variables and maximal exercise capacity has not been resolved. This study seeks to determine the effects of altering the increment of work-rate change per exercise stage on both the ischemic threshold and maximal exercise capacity using 2 frequently used exercise testing protocols. Thirty-two patients with documented coronary artery disease and previously positive exercise tests (ischemic ST depression greater than or equal to 1.0 mm) performed symptom-limited exercise tests using both the standard and modified Bruce protocols in random order, 1 hour apart. Exercise electrocardiograms were analyzed to determine the ischemic threshold, defined as heart rate at onset of greater than or equal to 1.0 mm ischemic ST depression. Patients achieved a higher peak heart rate (124 +/- 19 vs 117 +/- 21 beats/min; p less than 0.0001), rate-pressure product (21.4 +/- 3.9 vs 19.8 +/- 4.1 beats/min x mm Hg x 10(3); p less than or equal to 0.0001) and oxygen consumption (VO2) (18.5 +/- 3.7 vs 16.5 +/- 4.4 ml/kg/min; p less than or equal to 0.001) with the standard than with the modified Bruce protocol. At matched submaximal exercise stages there were no differences in VO2, heart rate or oxygen pulse between protocols. Time to ischemic threshold was significantly reduced with the standard compared with the modified Bruce protocol (312 +/- 107 vs 607 +/- 221 seconds; p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Dynamic arm exercise during cardiac catheterization in the assessment of stenotic valvular disease.

Assessment of hemodynamic responses during some form of exertion or stress during cardiac catheterization is useful among patients suspected of having valvular stenosis who demonstrate normal or borderline valve gradients at rest. Leg raising exercise and drug administration are commonly used for this purpose, but each has inherent limitations. To evaluate the usefulness of dynamic arm raising exercise as a means of altering hemodynamics during cardiac catheterization, 23 such patients were studied. Measurements obtained during arm raising exercise were compared with those at rest. Heart rate rose by 34 +/- 4 beats/min (p less than 0.001), while cardiac output increased by 1.4 +/- 0.2 l/min (p less than 0.001). Stroke volume decreased slightly, although left ventricular filling pressures and pulmonary capillary wedge pressures rose in nearly all subjects. The change in valvular gradients was variable. These data were compared with those obtained in 11 similar patients receiving either dopamine or isoproterenol as an intervention. The changes in heart rate and cardiac output from the resting state were similar between the groups, with fewer side effects occurring during arm exercise. Dynamic arm exercise is a safe and effective maneuver which can be performed during cardiac catheterization in patients undergoing diagnostic evaluation of stenotic valvular disease.

Adult↗
PubMed1990

Physiologic responses to arm ergometry exercise relative to age and gender.

Arm ergometry exercise testing is a valuable alternative method used in the evaluation and management of patients with both cardiac disease and lower limb impairment. The purpose of this study is to provide information concerning the physiologic responses of normal healthy subjects to arm ergometry relative to age and gender, which could serve as a standard for comparison. Eighty healthy subjects (age 22 to 59 years) cycled at 75 to 80 rpm (on a bicycle adapted for arm ergometry) starting at a power output of 10 W, increasing at 10 W/2 min until exhaustion. Sixty subjects were classified on the basis of age into three groups, each with 10 men and 10 women. Men achieved significantly (p less than 0.001) higher power output (95 +/- 25 W) and oxygen consumption (20.7 +/- 3.9 ml/kg per min) than did women (56 +/- 19 W and 15.5 +/- 3.1 ml/kg per min, respectively). The heart rate response to total body oxygen demand during arm ergometry was significantly higher in women than in men (p less than 0.001). These findings were also present when men and women of each age group were analyzed separately. Older subjects reached a significantly (p less than 0.02) lower peak power output than did younger subjects although they reached a similar level of oxygen consumption. Separate regression equations for predicting oxygen consumption at each power output were formulated for men and women and validated in 20 other subjects. Small differences in measured and predicted oxygen consumption at each stage were found. These data provide additional information concerning arm ergometry testing and should prove useful in diagnostic exercise testing and cardiac rehabilitation.

Adult↗
PubMed1990

Metastatic renal cell carcinoma. An unusual cause of syncope.

A 77-year-old man with a history of renal cell carcinoma presented with orthostatic syncope. Investigation revealed metastatic carcinoma in the left lung extending through the pulmonary veins into the left atrium obstructing the mitral orifice. On review of the literature, this case appears to be the first to describe metastatic carcinoma to the left atrium presenting as a primary cause of syncope.

Aged↗
PubMed1989

Utility of echocardiography in patients with suspected mitral valve prolapse.

PURPOSE: Echocardiography has become a widely utilized test since its introduction into clinical medicine in the early 1970s. Although it has frequently been performed in patients suspected of having mitral valve prolapse (MVP), its usefulness in this setting has not been systematically studied. To investigate the use and value of echocardiography in patients suspected of having MVP, we conducted a prospective study in which physicians were interviewed before and after ordering echocardiographic testing for patients in whom there was a suspicion of MVP. PATIENTS AND METHODS: The study population included consecutive patients referred to the echocardiography laboratory at Boston University Medical Center because of suspected MVP between January 1 and December 31, 1987. Two standardized telephone interviews were conducted with the physician most responsible for ordering the echocardiogram. The following information was obtained during the first interview, which was always conducted before the echocardiogram was performed: patient demographic and clinical data; the reason for ordering the echocardiogram; the physician's most likely clinical diagnosis; the physician's estimate of the likelihood that the patient had MVP; and the physician's proposed management plans. After the referring physician received the echocardiographic results, a second interview was conducted to determine changes in the most likely clinical diagnosis and management plans. The impact of the echocardiogram on diagnosis and management was evaluated by comparing physician responses before and after reception of echocardiographic results. Receiver operating characteristic (ROC) curves were constructed to assess the physician's skills at distinguishing patients with echocardiographic-documented MVP from those without MVP. RESULTS: A total of 106 echocardiograms were ordered by 45 different physicians. More than 80% of all echocardiograms were ordered to address diagnostic or therapeutic concerns. On echocardiography, 47 (44%) patients were found to have MVP, six (6%) had mitral regurgitation without prolapse, and 53 (50%) had normal results. On the basis of the ROC curve analysis, the physician's ability to discriminate between patients with and without echocardiographic MVP varied significantly by physician specialty and practice setting. The echocardiographic results led to a change in diagnosis in 59 (56%) patients. A change in management occurred in 29 (27%) patients, with 25 of these 29 changes (86%) related to the initiation or discontinuation of antibiotics. CONCLUSIONS: Echocardiography frequently alters diagnostic assessments and leads to therapeutic changes in some patients suspected of having MVP. However, the benefits of such changes have not yet been demonstrated.

Adult↗
PubMed1987

Arm exercise-thallium imaging testing for the detection of coronary artery disease.

Patients with lower limb impairment are often unable to undergo a standard bicycle or treadmill test for the evaluation of coronary artery disease. To establish an alternative method of testing, 50 subjects (aged 56 +/- 10 years) performed arm ergometry testing in conjunction with myocardial thallium scintigraphy. All underwent coronary angiography; significant coronary artery disease (greater than or equal to 70% stenosis) in at least one vessel was present in 41 (82%) of the 50 patients. Thallium scintigraphy was found to have an 83% sensitivity and 78% specificity for detecting coronary disease, compared with a sensitivity and specificity of 54% (p less than 0.01) and 67% (p = NS), respectively, for exercise electrocardiography. In the subgroup of 23 patients who had no prior myocardial infarction or left bundle branch block and were not taking digitalis, thallium scintigraphy had a sensitivity of 80% versus 50% for exercise electrocardiography. Scintigraphy yielded a sensitivity of 84, 74 and 90% for one, two and three vessel disease, respectively. Noninvasive arm ergometry exercise-thallium imaging testing appears to be reliable and useful and should be considered in the evaluation of coronary artery disease in patients with lower limb impairment.

Adult↗
PubMed1987

Exercise testing for sports and the exercise prescription.

The uses of the exercise test continue to grow and diversify. Familiarity with the mechanics, logistics, and interpretation of these tests leads to their optimal use. The application of exercise testing for competitive or recreational sports, cardiovascular fitness exercise training, and cardiac rehabilitation is the focus of this review. Many test protocols are available, but treadmill testing is the most widely used. The inclusion of thallium scintigraphy in the exercise protocol requires additional time and expense and is best reserved for those in whom the exercise electrocardiographic response cannot be adequately interpreted. Exercise testing is a relatively safe procedure, providing that adequate screening of individuals for unstable cardiac or medical conditions has been performed. The test must be administered by experienced personnel in a setting where the necessary emergency resuscitative equipment is available. Adequate interpretation of the exercise test requires knowledge of the individual being tested and of the reason the test is being performed. Complete analysis of the exercise test includes electrocardiographic response (ST segment changes and rhythm disturbances), hemodynamic response (heart rate and blood pressure before, during, and after exercise), and functional capacity (exercise duration, symptoms, conversion to MET's). When exercise tests are employed to establish a diagnosis of coronary artery disease, an assessment of the pretest likelihood (prevalence) of disease is essential in deriving a reasonable assessment of the probability of disease after the test has been performed and reviewed. This information is particularly important when screening asymptomatic subjects for underlying coronary disease before they engage in an exercise program. Exercise testing of individuals with known cardiac disease prior to engaging in competitive or recreational sports can yield much useful information. In addition to a knowledge of the underlying cardiac condition, the type and intensity of the sport being performed must be taken into account when exercise testing is performed for athletic screening. Individuals with congenital or acquired valvular heart disease, coronary artery disease, and rhythm disturbances should undergo an exercise test as part of the pretraining evaluation. Patients with ischemic heart disease, especially those who have had a recent myocardial infarction or have undergone coronary artery bypass surgery, require counseling regarding their ability to perform certain activities of daily living and to return to work. Exercise testing can be a useful tool in establishing activity guidelines for these individuals.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1986

Comparison of determinants of myocardial oxygen consumption during arm and leg exercise in normal persons.

Arm exercise assumes an increasingly important role in clinical cardiology as it is used in both exercise testing and training of patients with coronary artery disease. The effects of arm exercise on myocardial oxygen consumption are not well understood; they may differ from the effects of leg exercise. Previous studies have shown that the ischemic threshold is higher in patients performing arm exercise and leg exercise at the same heart rate-blood pressure product. The contribution of other determinants of myocardial oxygen consumption--left ventricular (LV) peak meridional systolic wall stress and contractility--to these observed differences were studied. Thirty healthy subjects exercised to the same peak rate-pressure product during dynamic upper- and lower-extremity exercise. Peak workload was lower during arm exercise (100 +/- 16 W) than during leg exercise (170 +/- 21 W, p less than 0.001). LV wall stress did not differ during either form of exercise (197 +/- 44 vs 204 +/- 33 dynes/cm2 X 10(3), arm vs leg, respectively). This was also true of contractility as assessed by the velocity of circumferential fiber shortening (2.8 +/- 0.6 vs 2.5 +/- 0.4 circ/s, arm vs leg, respectively) and the preejection period/LV ejection time ratio (0.33 +/- 0.11 vs 0.31 +/- 0.07, arm vs leg, respectively). Normal subjects exercising to a similar rate-pressure product showed the same levels of LV wall stress and contractility for arm and leg exercise despite the lower workload performed with arm exercise.

Adult↗
PubMed1986

Electrocautery and pacemakers: management of the paced patient subject to electrocautery.

Electrocautery, commonly used during surgery to maintain hemostasis, can have significant detrimental effects in the paced patient. Damage to the pulse generator, reprogramming of the pacemaker, changes in the capture threshold, and ventricular fibrillation can all be induced by electrocautery. Familiarity with the particular pacemaker in use is critical in minimizing these adverse effects. Preoperative evaluation of the patient's dependence on the pacemaker and evaluation of pacemaker function should be performed and documented. We recommend close intraoperative monitoring of heart rate and rhythm, and suggest that a pacemaker programmer be on hand in the surgical suite during the operation. A postoperative check of pacemaker function should be carried out so that electrocautery-induced pacemaker malfunction will not go unnoticed or uncorrected. Three cases are presented which clearly illustrate these points.

Aged↗
PubMed1985

Value of arm exercise testing in detecting coronary artery disease.

Alternative methods of exercise testing are needed for patients with vascular, orthopedic or neurologic conditions who cannot perform leg exercise. To determine the sensitivity of arm exercise in detecting coronary artery disease (CAD), 30 patients with angina pectoris performed both arm ergometry and treadmill testing before coronary angiography. All patients had at least 70% diameter reduction in 1 or more major coronary arteries. Ischemic ST depression (greater than or equal to 1 mm) or angina occurred more frequently (86%, 26 patients) with leg exercise than with arm exercise (40%, 12 patients). There was no significant difference in peak rate-pressure product achieved with either test, although the peak oxygen consumption was greater during leg exercise than during arm exercise (18 vs 13 ml/kg/min, respectively, p less than 0.001). For concordantly positive tests, the oxygen consumption at onset of ischemia was significantly lower during arm testing than during leg testing (12 vs 17 ml/kg/min, respectively, p less than 0.001). There was no significant difference in heart rate during either test at onset ischemia. Thus, arm exercise testing is a reasonable, but not equivalent, alternative to leg exercise testing in patients who cannot perform leg exercise.

Aged↗
PubMed1984

Electrocardiogram of the athlete: an analysis of 289 professional football players.

The electrocardiogram (ECG) of athletes reflects physiologic cardiovascular adaptations that occur in well-conditioned individuals. To more clearly define electrocardiographic changes seen in predominantly power-trained athletes, the ECGs of 289 apparently healthy professional football players were analyzed in detail. The players, aged 21 to 35 years, one-third of whom were black, had a mean body surface area of 2.24 m2, a mean heart rate at rest of 56 +/- 9 beats/min (with 77% (223) having a rate of less than 60 beats/min), and a mean P axis of 30 +/- 25 degrees. A wide QRS-T angle (greater than 60 degrees) was present in 14% (41 players) of the group. The mean PR interval was 0.18 +/- 0.02 second (greater than 0.21 in 9% [26 players]). Although two-thirds of the players had a QRS duration of 0.10 second, only 1 had right bundle branch block and none had left bundle branch block. The sum of S in lead V1 plus R in lead V5 averaged 37 +/- 9 mm, with 35% (101 players) demonstrating voltage criteria for left ventricular hypertrophy. The S + R value varied inversely with weight (r = -0.27, p less than 0.002). The maximum T height in any lead had a mean of 8.6 +/- 3 mm, with 22% (64 players) having a T height greater than or equal to 11 mm. U waves were universally present. ST-T changes mimicking ischemia were noted in 39 of 289 players (13%), 22 (58%) of whom were black (p less than 0.001). The maximal J-point elevation in any lead averaged 1.9 +/- 0.9 mm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Changes in exercise capacity following cardiac rehabilitation in patients stratified according to age and gender. Results of the Massachusetts Association of Cardiovascular and Pulmonary Rehabilitation Multicenter Database.

BACKGROUND: Using information collected prospectively from a multicenter cardiac rehabilitation database, this study was designed to evaluate baseline exercise tolerance and subsequent change in functional capacity among consecutive patients enrolled in supervised cardiac rehabilitation stratified according to age and gender. In addition, the study evaluated change in functional capacity among those with the lowest initial exercise tolerance (<5 METS) and assessed patient factors that correlate to the highest relative improvements in functional capacity after training. METHODS: A total of 778 patients performed an initial exercise test upon entry into cardiac rehabilitation, during which peak heart rate, blood pressure, and estimated peak MET levels were derived, and ischemic responses were evaluated. After 10 +/- 2 weeks of supervised prescribed exercise, 500 patients who completed the program performed follow-up exercise testing. RESULTS: The subjects included 558 men (72%) and 220 women (28%) of whom 492 (63%) were <65 years, 241 (31%) were 65 to 75 years, and 45 (6%) were >75 years. At baseline, the peak initial MET level for men was 8.6 +/- 3.4 METS and for women was 6.0 +/- 2.6 METs. The peak initial MET level declined with age: age <65 = 8.9 +/- 3.4 METS; age 65 to 75 = 6.6 +/- 2.6 METS; and age >75 = 5.7 +/- 2.9 METS. When stratified according to age and gender, the baseline exercise tolerance for men significantly (P <.0001) declined with age and was higher than that of women <65 and 65 to 75 years of age. After training, the relative improvement in exercise tolerance for each age and/or gender subgroup was: age <65: men 36%, women 41%; age 65 to 75: men 36%, women 50%; and age >75: men 36%, women 32%. Among 163 patients with an initial peak MET level <5, exercise tolerance rose from 4.1 +/- 0.7 to 8.3 +/- 3.5 METS (P <.0001). Multivariate analysis demonstrated that the greatest change in exercise tolerance with training was associated with those compliant patients with initial peak METS <5. No significant net change in the occurrence of exercise-induced ischemia was observed. CONCLUSIONS: Among consecutive patients enrolled in cardiac rehabilitation, baseline exercise tolerance differs relative to age and gender, with male gender and younger age demonstrating the highest functional capacity. Exercise training yielded significant improvements in exercise tolerance among men and women of every age group including those older than 75 years, and particularly among those with an initial peak MET level <5. Thus, referral to cardiac rehabilitation programs should be advocated for both men and women, and should not be limited by age.

Adult↗
PubMedDate not supplied

Prediction of oxygen uptake and energy expenditure during exercise in obese women.

PURPOSE: For patients concerned with weight loss, monitoring the energy balance between daily dietary intake and exercise expenditure can be useful. Formulas commonly used to estimate the energy costs of exercise were previously derived from healthy men of normal body weight. The purpose of this study was to determine the relationship between measured and predicted exercise energy expenditure for obese women. METHODS: Oxygen uptake (VO2) was measured using respiratory gas analysis in 45 obese (92 +/- 16 kg; 40 +/- 7% fat) and 10 normal weight (control) (58 +/- 5 kg; 21 +/- 6% fat) women during progressive exercise on a motorized treadmill. VO2 was also calculated at matched workrates using a regression equation published by the American College of Sports Medicine. The relationship between predicted versus measured VO2 was determined using least squares regression analysis. RESULTS: The slope of the regression line for measured versus predicted VO2 for controls (y = 0.98x +/- 0.56; P < .001) was different than that of obese women (y = 0.75x +/- 3.06; P < .001). The slope of the regression line for controls was in close approximation to the line of identity, whereas the slope for obese was below it. Using VO2 to calculate kcal, measured energy expenditure, was significantly lower than predicted energy expenditure for obese subjects, but not for controls at several matched workrates: Stage III (213 +/- 40 versus 225 +/- 38 kcal per 30 minutes, P < .001); stage 4 (292 +/- 55 versus 340 +/- 58 kcal per 30 minutes, P < .001); and stage 5 (330 +/- 55 versus 412 +/- 70 kcal per 30 minutes, P < .001) obese measured versus obese predicted, respectively. CONCLUSIONS: The authors conclude that the standard prediction equation gives a better estimation of VO2 for women who have average body weight and body fat than for obese women. This may, in part, be due to the differences in weight and/or fat mass between these subjects and those used to derive this equation. These findings should be considered when estimates of VO2 and energy expenditure are used rather than direct measures for obese women.

Adult↗
PubMedDate not supplied

Moderate-high intensity exercise training after myocardial infarction: effect on left ventricular remodeling.

BACKGROUND: Regular exercise increases exercise capacity and physical fitness, but questions remain about the effects of exercise on left ventricle (LV) remodeling after myocardial infarction. This study investigated the effects of moderate to high intensity exercise training on LV remodeling after a first myocardial infarction. METHODS: An exercise group of 68 patients in cardiac rehabilitation after a first myocardial infarction had an initial echocardiogram and exercise stress test. Thirty patients completed the 12 weeks of training and had echocardiograms suitable for quantitative analysis. Follow-up echocardiograms and exercise tests were performed. A carefully matched control group of 30 patients with echocardiograms at fixed intervals after myocardial infarction and no formal exercise training were also studied. LV size was expressed as the endocardial surface area-to-body surface area (ESAi), whereas infarct size was characterized by the percent abnormal wall motion (%AWM) by echocardiography using an endocardial surface area mapping technique. Indices of LV shape (sphericity) were also assessed. RESULTS: In the exercise group, no significant changes were seen in ESAi (57.95 +/- 13.1 vs 57.80 +/- 12.04 cm2/m2) or in %AWM (19.33 +/- 15.27 vs 20.11 +/- 15.95) from the initial to the final echo. The indices of sphericity were also unchanged. None of these parameters changed in the control group. Within each group was found heterogeneity in LV remodeling. Multivariate regression analysis revealed initial ESAi and initial %AWM to predict change in ESAi over time. CONCLUSIONS: In this study of patients with predominately small infarcts, exercise training did not adversely affect LV remodeling after myocardial infarction. Remodeling is heterogeneous and appears related to infarct and LV size.

Aged↗