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Results for “Exercise Tolerance”

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PubMed2000

[Comparison of dinitrate isosorbide retard forms in ischemic heart disease patients with stable effort angina].

AIM: To compare antianginal and anti-ischemic efficiency and tolerance of two forms of isosorbide dinitrate--cardiket-retard 120 mg and cardiket-retard 40 mg in IHD patients with stable effort angina. MATERIAL AND METHODS: The study included 18 IHD patients with stable angina of functional class II (5 patients) and III (13 patients). The trial was open cross-over. The treatment with both the forms lasted 1 month. Frequency of anginal attacks and exercise tolerance by veloergometry data were assessed. RESULTS: A significant decrease in the number of anginal attacks and greater exercise tolerance was recorded in cardiket 120 mg intake once a day. Both forms were well tolerated, serious side effects were absent. CONCLUSION: Comparison of the two isosorbide dinitrate dosage forms--cardiket 120 mg once a day and cardiket 40 mg 3 times a day--showed that the former is superior by clinical efficiency.

Adult↗

PubMed1985

A cooperative multicenter study of captopril in congestive heart failure: hemodynamic effects and long-term response.

The acute hemodynamic effects, long-term clinical efficacy, and safety of the oral angiotensin-converting enzyme inhibitor, captopril, were assessed in a multicenter cooperative study of 124 patients with heart failure resistant to digitalis and diuretics. The cardiac status of most patients was deteriorating prior to the study. Favorable acute hemodynamic effects consistently occurred with captopril. Maximal mean percentage increases in cardiac index, stroke index, and stroke work index were, respectively, 35%, 44%, and 34%. Systemic and pulmonary vascular resistances were each decreased by approximately 40%, as were the filling pressures of the right and left heart. Infusion of nitroprusside in some of the same patients to an end point of a pulmonary capillary wedge pressure of 12 to 18 mm Hg (equivalent to that after captopril) revealed no significant difference in the effect of either drug on the other hemodynamic parameters. Recatheterization after 8 weeks of captopril therapy revealed sustained hemodynamic changes. Significant and sustained improvements in clinical status were observed in most patients as measured by changes in New York Heart Association (NYHA) functional classification and exercise tolerance times. Seventy-nine percent of patients for whom there were adequate NYHA class data improved. Twenty percent remained unchanged and 1% deteriorated. Those patients who had both pretreatment and post-treatment exercise stress testing exhibited a highly significant mean increase in exercise tolerance times of 34% (317 +/- 32 seconds pretreatment to 425 +/- 34 seconds, final measurement). There was no evidence of tachyphylaxis over an 18-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Glucose-induced exertional fatigue in muscle phosphofructokinase deficiency.

BACKGROUND: The exercise capacity of patients with muscle phosphofructokinase deficiency is low and fluctuates from day to day. The basis of this variable exercise tolerance is unknown, but our patients with this disorder report that fatigue of active muscles is more rapid after a high-carbohydrate meal. METHODS AND RESULTS: To determine the effect of carbohydrate on exercise performance, we asked four patients with muscle phosphofructokinase deficiency to perform cycle exercise under conditions of differing availability of substrate--i.e., after an overnight fast, and during an infusion of glucose or triglyceride (with 10 U of heparin per kilogram of body weight) after an overnight fast. As compared with fasting and the infusion of triglyceride with heparin, the glucose infusion lowered plasma levels of free fatty acids and ketones, reduced maximal work capacity by 60 to 70 percent, and lowered maximal oxygen consumption by 30 to 40 percent. Glucose also increased the relative intensity of submaximal exercise, as indicated by a higher heart rate at a given workload during exercise. The maximal cardiac output (i.e., oxygen delivery) was not affected by varying substrate availability, but the maximal systemic arteriovenous oxygen difference was significantly lower during glucose infusion (mean +/- SE, 5.5 +/- 0.3 ml per deciliter) than after fasting (7.6 +/- 0.4 ml per deciliter, P less than 0.05) or during the infusion of triglyceride with heparin (8.9 +/- 1.3 ml per deciliter, P less than 0.05). CONCLUSIONS: In muscle phosphofructokinase deficiency, the oxidative capacity of muscle and the capacity for aerobic exercise vary according to the availability of blood-borne fuels. We believe that glucose infusion lowers exercise tolerance by inhibiting lipolysis and thus depriving muscle of oxidative substrate (plasma free fatty acids and ketones); this impairs the capacity of working muscle to extract oxygen and lowers maximal oxygen consumption.

Adolescent↗

PubMedDate not supplied

[Biventricular resynchronization in the treatment of chronic heart failure].

Chronic heart failure (CHF) caused by systolic dysfunction is a disease of epidemic proportions. Although pharmacological therapy has ameliorated symptoms and improved the survival of these patients, this chronic syndrome remains a progressive disease, causing incremental morbidity and early mortality. Preliminary studies show that ventricular resynchronization significantly improves exercise tolerance and the quality of life in patients with CHF who have sinus rhythm and major intraventricular conduction delay. Cardiac-resynchronization therapy requires in synchrony with atrial activity. Atriobiventricular pacing significantly improved symptoms, exercise tolerance and the quality of life. The use of this procedure today should be individualized however, further studies are needed to assess the long-term clinical effect of this therapeutic approach.

Cardiac Pacing, Artificial↗

PubMed1989

Applicability of a threshold loading device for inspiratory muscle testing and training in patients with COPD.

We evaluated application of a Pth device for testing inspiratory muscle endurance among patients with severe but stable COPD. Endurance time in five patients was reproducible. Magnitude of variability was +/- 1.26 minutes with a range of +/- 0.19 to +/- 2.28 minutes. Eleven inpatients completed inspiratory muscle training twice daily for four weeks in addition to their usual program of respiratory rehabilitation. The mean age of our experimental cohort was 65 years; FEV1, 33 +/- 12 percent predicted; and Dsb, 42 +/- 7 percent predicted. Baseline measurements showed no significant differences in pulmonary function, exercise tolerance, inspiratory muscle strength or inspiratory muscle endurance between control and study groups. Following training, the study group significantly improved inspiratory muscle endurance as evidenced by an increase in endurance time while breathing against the same absolute external Pth load used during baseline assessments. There were no associated changes in lung mechanics, muscle strength or exercise tolerance.

Aged↗

PubMed1991

Post-prandial worsening of angina: all due to changes in cardiac output?

BACKGROUND: The precise mechanism leading to the post-prandial worsening of angina has yet to be adequately defined. It has been attributed to an increase in double product but is perhaps more likely to be related to an increase in cardiac output after food. This study was designed to evaluate the effects of food on patients' exercise tolerance and compare these with changes in haemodynamic variables. METHODS: 23 patients with chronic stable angina who had post-prandial worsening of their angina were studied. The patients were evaluated on two occasions and at each visit they underwent two symptom limited treadmill exercise tests. They remained fasting on the first visit and were given a 1400 kcal meal 60 minutes before the second exercise test on the second visit. Time to onset of 1 mm ST segment depression, heart rate, systemic arterial blood pressure, and cardiac output were measured at rest and during exercise. RESULTS: There were no differences in any of the variables during the two exercise tests on the day the patients remained fasting. After the meal exercise tolerance fell significantly by 136 seconds and the stage at which 1 mm ST segment depression was first seen was also significantly reduced. Resting cardiac output increased significantly by 0.86 1/min with the patients sitting and by 0.89 1/min standing. The exercise times after food were significantly related to cardiac output even when fasting times were taken into account. Resting heart rate increased significantly by 8.3 beats per minute sitting and 10.4 beats per minute standing. There was little change in blood pressure and no evidence that the double product predicted the post-prandial exercise time. CONCLUSIONS: Worsening of angina was related to the increase in cardiac output after a meal and successful treatment will depend upon the prevention of this increase.

Aged↗

PubMed1985

[Potentials of noninvasive methods in diagnosing multiple coronary artery lesions in ischemic heart disease].

A total of 111 patients, aged 35 to 60, were examined. Of those, 97 had survived transmural or large-focal myocardial infarction (MI) 1-2 years before the study. The patients were divided into groups according to MI localization and the number of affected coronary arteries. Coronaro- and ventriculography, echocardiography (sectoral scanning), the computer-assisted treadmill exercise test were performed in all the patients. Exercise tolerance in post-MI patients was shown to be related to coronary circulation and unrelated to left-ventricular myocardial contractility at rest. The analysis of ST variation, particularly ST rise, as the only criterion for the assessment of the results of exercise testing demonstrated its moderate sensitivity in relation to the diagnosis of multiple coronary arterial lesions (MCAL) in post-MI patients. The informative value of the test increases if other parameters, particularly exercise tolerance, are assessed as well. Low tolerance combined with computer evidence of a positive test is in most cases indicative of MCAL, whereas with high tolerance in the absence of electrocardiographic ST changes MCAL would be unlikely.

Adult↗

PubMed2002

Effect of nutritional antioxidant supplementation on systemic and pulmonary antioxidant status, airway inflammation and lung function in heaves-affected horses.

An oxidant/antioxidant imbalance in favour of oxidants has been identified as playing a decisive role in the pathogenesis of chronic inflammatory airway diseases. Nutritional antioxidant supplementation might reduce oxidative damage by enhancement of the antioxidant defence, thereby modulating inflammatory processes. In a placebo-controlled, blind study, it was tested whether a dietary antioxidant supplement administered for 4 weeks would improve lung function and reduce airway inflammation in heaves-affected horses. Eight horses in clinical remission of heaves were investigated at rest and after a standardised exercise test before and after treatment with an antioxidant supplement (consisting of a mixture of natural antioxidants including vitamins E and C and selenium from a variety of sources) or placebo (oatfeed pellets without additive). Pulmonary function and exercise tolerance were monitored; systemic and pulmonary lining fluid uric acid, glutathione and 8-epi-PGF(2alpha) were analysed, and bronchoalveolar lavage (BAL) cytology and inflammatory scoring of the airways were performed. The antioxidant treatment significantly improved exercise tolerance and significantly reduced endoscopic inflammatory score. Plasma uric acid concentrations were significantly reduced, suggesting downregulation of the xanthine-dehydrogenase and xanthine-oxydase pathway. Haemolysate glutathione showed a nonsignificant trend to increase, while plasma 8-epi-PGF(2alpha) remained unchanged. Pulmonary markers and BAL cytology were not significantly affected by antioxidant supplementation. The present study suggests that the antioxidant supplement tested modulated oxidant/antioxidant balance and airway inflammation of heaves-affected horses.

Animals↗

PubMed2000

The short- and mid-term results of bidirectional cavopulmonary shunt with additional source of pulmonary blood flow as definitive palliation for the functional single ventricular heart.

OBJECTIVE: The purpose of this study was to demonstrate the early and late outcomes of bidirectional cavopulmonary shunt (BCPS) as a definitive procedure for the functional single ventricular heart. METHOD: From September 1991 to December 1997, 34 patients underwent a BCPS procedure without a routine conversion to Fontan circulation. The additional source of pulmonary blood flow was left in all patients. Conversion was performed only when it was required for excessive cyanosis. RESULTS: The hospital mortality rate was 8.8% (3/34, 95% confidence limit; 1.9-23%) and the 5-year survival rate was 75% for a mean follow-up period of 33+/-22 months. Seven patients underwent a conversion procedure for remnant or recurrent cyanosis and deterioration of exercise tolerance. Four of these patients died after conversion to Fontan circulation. Twenty-five long-term survivors with BCPSs maintained an arterial oxygen saturation of 84+/-6.1%, and 52% of them had a normal exercise tolerance or mild limitation. No patients developed severe late complications other than recurrent cyanosis. CONCLUSION: Due to the high mortality after conversion to Fontan circulation in patients whose conditions had deteriorated, we could not demonstrate the clear superiority of long-term BCPS over the construction of Fontan circulation for management of the functional single ventricular heart. If deteriorated conditions were successfully managed in the late period, the outcome of long-term BCPS would have been better.

Adolescent↗

PubMed1999

Physiological responses of horses to a treadmill simulated speed and endurance test in high heat and humidity before and after humid heat acclimation.

To investigate whether horses were able to acclimate to conditions of high temperature and humidity, 5 horses of different breeds were trained for 80 min on 15 consecutive days on a treadmill at 30 degrees C and 80%RH. Training consisted of a combination of long duration low-intensity exercise, medium duration medium intensity exercise and short duration high intensity exercise. Between training sessions the horses were maintained at 11+/-3 degrees C and 74+/-2%RH. Before (PRE-ACC) and after acclimation (POST-ACC) the horses undertook a simulated Competition Exercise Test (CET), designed to represent the Speed and Endurance Test of a 3-day event, at 30 degrees C/80%RH. Maximal oxygen uptake (VO2PEAK) was not changed following acclimation (PRE-ACC 141+/-8 ml/min/kg bwt vs. POST-ACC 145+/-9 ml/min/kg bwt [STPD], P>0.05). Following acclimation, 4 of the 5 horses were able to complete a significantly greater amount of Phase D in the CET (PRE-ACC 6.3+/-0.3 min vs. POST-ACC 7.3+/-0.3 min, P<0.05; target time = 8 min). Resting body temperatures (pulmonary artery [TPA], rectal [TREC] and tail-skin [TTSK] temperatures) were all significantly lower following acclimation. During exercise, metabolic heat production (M) and heat dissipation (HD), for the same exercise duration, were both significantly lower following acclimation (P<0.05), although heat storage (HS) was significantly higher (P<0.05). The higher heat storage following acclimation was associated with a lower TTSK for a given TPA and a decreased total fluid loss (% bodyweight, P<0.05). Plasma volume was not changed following acclimation. The relationship of sweating rate (SR) to TPA or TTSK on either the neck or the gluteal region was not significantly altered by acclimation, although the onset of sweating occurred at a lower TPA or TTSK following acclimation (P<0.05). The horses in the present study showed a number of physiological adaptations to a period of 15 days of exposure to high heat and humidity consistent with a humid heat acclimation response. These changes were mostly similar to those reported to occur in man and other species and were consistent with thermal acclimation and an increased thermotolerance, leading to an improved exercise tolerance. It is concluded that a 15 day period of acclimation is beneficial for horses from cooler and or drier climates, that have to compete in hot humid conditions and that this may redress, to some extent, the decrement in exercise tolerance seen in nonacclimated horses and reduce the risk of heat related disorders, such as heat exhaustion.

Acid-Base Equilibrium↗

PubMed1999

Systemic sclerosis-associated pulmonary hypertension: short- and long-term effects of epoprostenol (prostacyclin).

OBJECTIVE: To evaluate the short- and long-term effects of intravenous epoprostenol in patients with pulmonary hypertension (PH) associated with systemic sclerosis (SSc). METHODS: Sixteen patients with SSc-associated PH and New York Heart Association (NYHA) class III or IV symptomatology underwent right heart catheterization for determination of baseline hemodynamic values. Vasoreactivity was assessed with either inhaled nitric oxide or intravenous adenosine. After a medication washout period, all patients received intravenous epoprostenol in incrementally increasing doses; tolerance was assessed according to symptoms and hemodynamic findings at each dose increment and at the conclusion of the medication trial. Once a stable medication regimen was established, patients were discharged and followed up as outpatients for assessment of symptoms and exercise tolerance as measured by change in the NYHA class. Repeat hemodynamic testing was performed in 4 patients at 1 year and in 2 patients at 2 years of treatment. RESULTS: Therapeutic response to epoprostenol, defined by a reduction in the pulmonary vascular resistance of > or =25%, was achieved in the short-term treatment period in 13 of 16 patients (81.3%). Improvement in symptoms and exercise tolerance occurred in all patients, and a significant short-term hemodynamic response was observed. Followup hemodynamic tests revealed persistent favorable responses in all 4 of the patients studied. CONCLUSION: Most patients with PH secondary to SSc manifest favorable hemodynamic responses to epoprostenol in the short term. Long-term epoprostenol was generally well tolerated and provides a potential therapeutic option for patients with PH secondary to SSc.

Adult↗

PubMed2002

Pulmonary artery pressure-flow relations after prostacyclin in primary pulmonary hypertension.

Exercise tolerance improves within a few weeks after prostacyclin initiation in patients with primary pulmonary hypertension even in the absence of significant changes in resting pulmonary vascular resistance and/or in patients who fail to respond to an acute vasodilator challenge. We tested the hypothesis that this early effect of prostacyclin may be ascribable to an improved pressure-flow response of the pulmonary circulation to exercise. Pulmonary hemodynamic variables at rest and during exercise and the 6-min walking distance were determined before and after 6 wk of continuous intravenous prostacyclin treatment (11 +/- 1.5 ng/kg/min) in seven patients unresponsive to an acute nitric oxide vasodilator test. Mean pulmonary arterial pressure/cardiac index coordinates obtained during exercise were pooled, and the slopes of these plots were compared using covariance analysis. All hemodynamic variables at rest were unchanged after prostacyclin. By contrast, the 6-min walking distance improved in all patients (mean increase, 81 m) and the slope of the mean pulmonary artery pressures/cardiac indexes plot decreased with prostacyclin, from 18.2 to 13.1 mm Hg/L/min/m(2) (p < 0.01). These results suggest that the improvement in exercise tolerance seen after 6 wk of prostacyclin therapy may be ascribable to a decrease in incremental pulmonary vascular resistance during exercise.

Antihypertensive Agents↗

PubMedDate not supplied

[Laser posterior cordectomy in bilateral vocal cord paralysis].

OBJECTIVES: We evaluated the functional results of laser posterior cordectomy with respect to respiration, phonation, and deglutition. PATIENTS AND METHODS: Unilateral laser posterior cordectomy was performed in nine patients (7 women, 2 men; mean age 56 years; range 46 to 61 years) with bilateral vocal cord paralysis. Postoperatively, respiration, deglutition, and phonation were evaluated with the use of an exercise tolerance scale, the Pearson scale, and wavelet analysis, respectively. The mean follow-up period was 14.2 months. RESULTS: Respiration was satisfactory in eight patients. Of these, four patients had excellent, and four patients had good exercise tolerance. The procedure resulted in success without tracheotomy in four patients. No deglutition or aspiration problems developed. Of eight patients with satisfactory respiration, voice quality remained unchanged in six patients, whereas an improved voice quality was noted in two patients who received postoperative phoniatric rehabilitation. CONCLUSION: Laser posterior cordectomy for the treatment of bilateral vocal cord paralysis resolves respiration problems, it restores phonation and deglutition functions, as well.

Deglutition↗

PubMed1989

[Evaluation of long-term postoperative status and cardiac function in patients with tetralogy of Fallot].

This study was undertaken to clarify the long-term post-operative state of patients with tetralogy of Fallot (TF). Total number of 243 patients with TF who underwent corrective surgery between 1965 and 1984 were investigated by the follow-up study. Cardiac function was evaluated by Holter ECG (for 48 patients), Treadmill exercise tolerance test (for 74 patients), and cardiac catheterization (for 56 patients). Twenty-year's follow-up revealed 13 patients (5.3%) of late deaths, and 10 of them were cardiac deaths. Three patients (1.2%) expired by sudden death. Nineteen female patients experienced 26 deliveries. No patients required artificial abortion due to heart failure during pregnancies. No baby with cardiac anomaly was born by these mothers. Holter ECG showed complex ventricular arrhythmias in 23 patients (48%). The high systolic pressure ratio of right ventricle to aorta, the old age at surgery, and the long elapsed time after surgery, were the three major aggravating factors of complex ventricular arrhythmias after the correction of TF. Treadmill tests disclosed that patients with poor exercise tolerance had low RVEF and high RVEDP, indicating that RV dysfunction limited the exercise capacity in the long-term postoperative state. Among the three methods of RV outflow tract reconstruction, the follow-up data showed that patients with right ventricular patch below pulmonary valve had better event-free rate compared to those with transannular patch or to those with extensive muscle resection without patch enlargement. Cineangiogram revealed that patients with transannular patch had biventricular enlargement, but the cardiac function did not differ among the three RV outflow reconstructive methods. Because 15 years after surgery the event-free rate decreases gradually and the arrhythmia problem becomes prominent, it is concluded that patients with TF should be followed and observed carefully even though they are currently in the healthy state.

Adolescent↗

PubMed1979

Antianginal efficiency of nifedipine with and without a beta-blocker, studied with exercise test. A double-blind, randomized subacute study.

Twenty-one patients, mean age 60.3 years, with stable angina pectoris earlier treated with beta-blockers, were investigated with standardized exercise tests to evaluate the action of nifedipine alone and in combination with a beta-blocker. The first exercise test was performed 3 weeks after treatment with the patient's usual beta-blocker. Following this, the patients were tested twice after a double-blind cross-over 3-week trial with nifedipine and placebo. The patients were subsequently treated for 3 weeks with nifedipine 10 mg 3 times daily or placebo and then performed an exercise test. During the 4th period of 3 weeks the patients took a combination of nifedipine, 10 mg 3 times daily, and their usual beta-blocker and then performed the final exercise test. Nifedipine alone raised the heart rate by 5 beats/min at rest and diminished the systolic blood pressure at rest by 17 mm Hg. During exercise at comparable load the heart rate did not change significantly, but the systolic blood pressure decreased with 22 mm Hg. The exercise tolerance expressed as total work increased on a average by 20%, range-14 - + 194%. Nifedipine in combination with a beta-blocker gave a further decrease in the systolic blood pressure, totally 37 mm Hg at comparable load. The exercise tolerance increased more, totally by an average of 41%. There was a significant correlation between basal values for systolic blood pressure registered during the placebo period at rest and the percentage change in total work. The atrioventricular conduction time did not change significantly compared to placebo during treatment with nifedipine or the combination nifedipine + beta-blocker. No serious side-effects were observed during the study.

Aged↗

PubMed1983

[Effect of atenolol and nitroglycerin ointment on exertion tolerance in coronary disease].

In a randomized, placebo-controlled double-blind cross-over study the effect and duration of effect of 2% nitroglycerin ointment (2 cm/m2 body surface) and 50 mg atenolol, as the only drug or the two in combination, were tested on 16 patients with coronary heart disease. Heart rate at rest and on exercise rose significantly for up to 3 1/2 hours (P less than 0.01) after application of the nitroglycerin ointment. Systolic blood pressure at rest and five minutes after exercise was significantly reduced (P less than 0.01), while on exercise there was no significant difference from the control value. Pressure X heart rate product was significantly raised over the initial value up to 3 1/2 hours after application, at maximal exercise (P less than 0.05), while after atenolol there was a highly significant reduction compared with the placebo (P less than 0.01), even after six hours. S-T depression was reduced at maximal comparable exercise level by 49% after atenolol, 52% after nitroglycerin ointment and 76% after combination of the two (P less than 0.05). Exercise tolerance was on average increased for 1 1/2 hours after atenolol by 36%, after nitroglycerin ointment by 58% and after the combined application by 84%, compared with the placebo (P less than 0.01). In the latter (combination) group the pressure X heart rate product was definitely below that of the nitroglycerin ointment group. Thus additional administration of 50 mg atenolol can decrease the pressure X heart rate product after application of nitroglycerin ointment, at the same time increasing exercise tolerance and reducing the degree of S-T depression.

Aged↗

PubMed1982

Calcium channel blockade as primary therapy for stable angina pectoris. A double-blind placebo-controlled comparison of verapamil and propranolol.

The effectiveness and safety of the beta-adrenergic blocking agent propranolol and the calcium channel antagonist verapamil were compared in 22 patients with chronic stable angina pectoris using a double-blind randomized placebo-controlled crossover protocol. The double-blind phase was preceded by a 2 week single-blind placebo period, followed by randomization to either 4 weeks' therapy with verapamil, 360 mg/day, or propranolol, 240 mg/day, followed by crossover to the other drug. Both verapamil and propranolol increased exercise tolerance (5.5 +/- 0.4 minutes with placebo, 7.8 +/- 0.5 minutes with propranolol [p less than 0.001], and 9.1 +/- 0.5 minutes with verapamil [p less than 0.001]), but the increase with verapamil was significantly greater (p less than 0.01). Both drugs prolonged the exercise duration to 1 mm S-T depression (3.3 +/- 0.4 minutes with placebo, 5.7 +/- 0.5 minutes with propranolol [p less than 0.001] and 5.5 +/- 0.6 minutes with verapamil [p less than 0.001]); the degree of improvement was similar with both active drugs. Both drugs decreased the resting heart rate (76 +/- 3 beats/min with placebo, 56 +/- 2 beats/min with propranolol [p less than 0.001], and 71 +/- 3 beats/min with verapamil [p less than 0.01]), but the heart rate decreased more with propranolol than with verapamil (p less than 0.001). Neither drug produced significant adverse reactions. This study, along with 8 similar double-blind placebo-controlled randomized investigations which have compared verapamil with propranolol, indicate that verapamil is as effective and safe as propranolol in relieving symptoms and improving exercise tolerance in patients with chronic stable angina pectoris and may be considered a first-line therapeutic agent in patients with ischemic heart disease.

Adrenergic beta-Antagonists↗

PubMed1990

Chronotropic response to exercise in patients with atrial fibrillation.

The exercise chronotropic response of patients with chronic atrial fibrillation requiring pacemaker therapy for bradycardia was assessed to characterize the chronotropic response and identify patients who would potentially benefit from a rate adaptive pacemaker. The population consisted of all patients who received a VVI pacemaker between January 1980 and November 1987 who underwent exercise tolerance testing (n = 130) and were in atrial fibrillation (n = 19). There were 11 males and 8 females with a mean age of 62 +/- 14 years. Left ventricular function was normal in eight patients, mildly impaired in three, and severely impaired in two. Long-term medications were continued until the morning of the test; digoxin 73%, beta blockers 21%, calcium channel blockers 26%, and nitrates 21%. Maximal exercise tolerance tests were performed. Parameters assessed were: (a) heart rate at rest, the end of each stage, and at peak exercise; (b) percent heart rate reserve per stage; and (c) percent metabolic reserve per stage. Results were compared to 100 normal subjects on no medications and without evidence of medical illness or cardiac disease. Heart rates were depressed in 58% of the study patients (21% early, 53% late) and elevated in 74% (74% early, 32% late). All 19 (100%) patients had abnormal heart rate responses at some point during the exercise test. Only four patients (21%) had a response within one standard deviation from the mean of the normal population during either the early or late segment of the exercise test. Patients in chronic atrial fibrillation requiring pacemakers for bradycardiac support at rest have an abnormal chronotropic response to exercise.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗