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PubMed1993

Oral corticosteroids in patients with mild Pneumocystis carinii pneumonia and the acquired immune deficiency syndrome (AIDS).

OBJECTIVE: To assess the effect of oral corticosteroids in patients with mild Pneumocystis carinii pneumonia and the acquired immune deficiency syndrome (AIDS). DESIGN: Prospective, double blind, placebo controlled, randomized trial. METHODS: Included were AIDS patients having their first episode of P. carinii pneumonia, who had no other known active pulmonary pathology, who had no contraindications for corticosteroids and who had received no other anti-P. carinii medications for more than 48 h. Subjects received either prednisone, 60 mg/day for 7 days, followed by a progressive tapering over 14 days, or identical placebo. The present analysis pertains to patients with mild P. carinii pneumonia as defined by a baseline resting oxygen saturation greater than 90% and a decrease in oxygen saturation during exercise while breathing room air of not less than 5 percentage points. Early deterioration, the end-point of the trial, was defined as a 10% decrease from baseline oxygen saturation on day 3 or thereafter. RESULTS: At study termination, there were 12 subjects in the placebo group and 11 in the corticosteroid group. Baseline characteristics were not statistically different between the treatment groups. Early deterioration developed in 7 and 1 patients in the placebo and corticosteroid groups respectively (P = 0.027). In addition, by day 3, a number of parameters were less favorable in the placebo group relative to the corticosteroid group including median oxygen saturation (85% vs 97%; P = 0.003), lactic dehydrogenase (1514 vs 763; P = 0.013), median respiratory rate (30 vs 22; P = 0.003), median heart rate (100 vs 81; P = 0.002), and median temperature (39 vs 37; P = 0.024). Even though patients suffering early deterioration in the placebo group were switched to corticosteroids, significant differences between the groups remained at day 30 with regard to exercise tolerance. More than half of patients assigned to the corticosteroid group exercised for a median of 6.5 min on day 30 (P = 0.017). CONCLUSION: Oral corticosteroids prevent early deterioration and increase exercise tolerance in patients with mild AIDS-related P. carinii pneumonia as defined on the basis of pulse oximetry.

AIDS-Related Opportunistic Infections↗

PubMed2000

The evidence regarding the drugs used for ventricular rate control.

OBJECTIVE: Our goal was to determine what drugs are most efficacious for controlling the ventricular rate in patients with atrial fibrillation. SEARCH STRATEGY: We conducted a systematic review of the literature published before May 1998, beginning with searches of The Cochrane Collaboration's CENTRAL database and MEDLINE. SELECTION CRITERIA: We included English-language articles describing randomized controlled trials of drugs used for heart rate control in adults with atrial fibrillation. DATA COLLECTION/ANALYSIS: Abstracts of trials were reviewed independently by 2 members of the study team. We reviewed English-language abstracts of non-English-language publications to assess qualitative consistency with our results. MAIN RESULTS: Forty-five articles evaluating 17 drugs met our criteria for review. In the 5 trials of verapamil and 5 of diltiazem, heart rate was reduced significantly (P <.05), both at rest and with exercise, compared with placebo, with equivalent or improved exercise tolerance in 6 of 7 comparisons. In 7 of 12 comparisons of a beta-blocker with placebo, the beta-blocker was efficacious for control of resting heart rate, with evidence that the effect is drug specific, as nadolol and atenolol proved to be most efficacious. All 9 comparisons demonstrated good heart rate control with beta-blockers during exercise, although exercise tolerance was compromised in 3 of 9 comparisons. In 7 of 8 trials, digoxin administered alone slowed the resting heart rate more than placebo, but it did not significantly slow the rate during exercise in 4 studies. The trials evaluating other drugs yielded insufficient evidence to support their use, but those drugs may yet be promising. CONCLUSIONS: The calcium-channel blockers verapamil or diltiazem, or select beta-blockers are efficacious for heart rate control at rest and during exercise for patients with atrial fibrillation without a clinically important decrease in exercise tolerance. Digoxin is useful when rate control during exercise is less a concern.

Adrenergic beta-Antagonists↗

PubMed1995

Low intensity exercise training in patients with chronic heart failure.

OBJECTIVES: The present study was designed to evaluate whether a specific program of low intensity exercise training may be sufficient to improve the exercise tolerance of patients with chronic heart failure. BACKGROUND: Recent studies have shown that exercise training can improve exercise tolerance in patients with stable chronic heart failure, mainly through peripheral adaptations. These changes have been observed with exercise regimens at intensities of 70% to 80% of peak oxygen uptake and > 8 weeks. METHODS: We studied 27 patients (23 men, 4 women; mean [+/- SD] age 57 +/- 6 years) with mild chronic heart failure. We classified patients into two groups: trained group and untrained group. The trained group underwent a low intensity (40% of peak oxygen uptake) training program three times/week for 8 weeks. The untrained group performed no exercise. RESULTS: An increase in peak oxygen uptake (17%, p < 0.0001), lactic acidosis threshold (20%, p < 0.0002) and peak work load (21%, p < 0.0002) were obtained in the trained group only. Cardiac output and stroke volume were unchanged. A high correlation was found between the increases in peak oxygen uptake and volume density of mitochondria of vastus lateralis muscle (r = 0.77, p < 0.0002). CONCLUSIONS: Patients with stable chronic heart failure can achieve significant improvement in functional capacity from a low intensity exercise training regimen. The mechanism responsible for this favorable effect involves an increase in mitochondrial density, which reflects an improvement in oxidative capacity of trained skeletal muscles.

Anaerobic Threshold↗

PubMed2000

Effects of 7 years of growth hormone replacement therapy in hypopituitary adults.

Short-term studies of GH replacement in adult hypopituitarism have usually demonstrated beneficial effects on body composition and circulating lipids, with neutral or occasionally adverse effects on glucose tolerance. Fasting hyperinsulinemia has been reported. GH effects on cardiac function have been variable. The effects of long-term GH therapy, taking into account the consequences of increasing age, are not fully known. Thirty-three hypopituitary, initially middle-aged adults were studied over a 7-yr period; 12 patients took GH therapy (mean, 0.7 mg daily) continuously (group A); 11 took GH for only 6-18 months, a minimum of 5 yr previously (group B); and 10 patients never received GH therapy (group C). Other pituitary replacement was maintained. Effects on anthropometry, body composition (by bioimpedance analysis, total body potassium, and dual energy x-ray absorptiometry), circulating lipids, glucose and insulin concentrations, cardiac 2-dimensional and Doppler echocardiography, and exercise tolerance were assessed before and after the treatment period. Continuous GH therapy had no significant effect on body weight, but it prevented the increase in waist circumference and waist to hip ratio that occurred in the patients without GH substitution (waist to hip ratio, group A, 0.87+/-0.08 at baseline, 0.85+/-0.09 at 7 yr; group B, 0.89+/-0.11 at baseline, 0.94+/-0.11 at 7 yr; P < 0.005 for GH effect; group C, 0.87+/-0.10 at baseline, 0.92+/-0.10 at 7 yr; P < 0.005 for GH effect). A GH-induced decrease in subscapular skinfold thickness was also observed. By bioimpedance analysis, GH therapy caused an increase in total body water and fat-free mass, and a decrease in the percent body fat. Although changes occurred with time in all groups, no significant additional GH therapy effects were observed on glucose tolerance, insulin concentrations, lipid levels, cardiac dimensions, echocardiographic diastolic function, or exercise tolerance. In conclusion, prolonged GH substitution in middle-aged hypopituitary adults causes a sustained improvement in body composition. Other benefits, e.g. on lipid levels and exercise tolerance, were not apparent at 7 yr when comparisons were made with GH-untreated hypopituitary controls. Potentially adverse effects on glucose tolerance and insulinemia did not develop with prolonged GH therapy.

Absorptiometry, Photon↗

PubMed2000

Percutaneous transmyocardial laser revascularisation for severe angina: the PACIFIC randomised trial. Potential Class Improvement From Intramyocardial Channels.

BACKGROUND: Percutaneous transmyocardial laser revascularisation (PTMR) is a proposed catheter-based therapy for refractory angina pectoris when bypass surgery or angioplasty is not possible. We undertook a randomised trial to assess the safety and efficacy of this technique. METHODS: 221 patients with reversible ischaemia of Canadian Cardiovascular Society angina class III (61%) or IV (39%) and incomplete response to other therapies were recruited from 13 centres. Patients were randomly assigned PTMR with a holmium:YAG laser plus continued medical treatment (n=110) or continued medical treatment only (n=111). The primary endpoint was the exercise tolerance at 12 months. Analyses were by intention to treat. FINDINGS: 11 patients died and 19 withdrew; 92 PTMR-group and 99 medical-treatment-group patients completed the study. Exercise tolerance at 12 months had increased by a median of 89.0 s (IQR -15 to 183) with PTMR compared with 12.5 s (-67 to 125) with medical treatment only (p=0.008). On masked assessment, angina class was II or lower in 34.1% of PTMR patients compared with 13.0% of those medically treated. All indices of the Seattle angina questionnaire improved more with PTMR than with medical care only. By 12 months there had been eight deaths in the PTMR group and three in the medical treatment group, with similar survival in the two groups. INTERPRETATION: PTMR was associated with increased exercise tolerance time, low morbidity, lower angina scores assessed by masked reviewers, and improved quality of life. Although there is controversy about the mechanism of action, and the contribution of the placebo effect cannot be quantified, this unmasked study suggests that this palliative procedure provides some clinical benefits in the defined population of patients.

Adult↗

PubMed1983

A comparison of once and twice daily atenolol for angina pectoris.

We have studied the effects of four doses of atenolol in 11 patients with stable angina pectoris using a symptom-limited exercise test and angina diaries. The doses 100 mg twice daily and 50 mg, 100 mg and 200 mg once daily were given double-blind and randomised within patients following run-in on placebo. Measurements were made 12 hours after the last twice daily dose and 24 hours after the last once daily dose. Exercise tolerance was improved by 40-74% and exercise duration before the onset of angina by 61-94% (P less than 0.01). Maximal heart rate was reduced further by a total daily dose of 200 mg than by lower doses, but no extra benefit was derived by giving the drug twice daily. The largest increase in exercise tolerance was obtained during treatment with 50 mg once daily. Atenolol was shown to be an effective anti-anginal agent when given once daily, and there were no major differences between the doses studied.

Adult↗

PubMed2003

Comparison of three-field esophagectomy for esophageal cancer incorporating open or thoracoscopic thoracotomy.

BACKGROUND: Thoracoscopic esophagectomy for esophageal cancer has been performed as an alternative to open surgery to reduce surgical trauma. However, its effect on pulmonary function, exercise tolerability, and quality of life is unknown. METHODS: Fifty-one patients with esophageal cancer underwent thoracic esophagectomy with radical lymphadenectomy by posterolateral thoracotomy (29 cases) or thoracoscopic surgery (22 cases). Patients performed spirometry and exercise tolerance testing and completed a quality-of-life questionnaire before and 3 months after surgery. RESULTS: Pre-to-postoperative change in vital capacity was 74.3 +/- 10.6% in the thoracotomy group and 84.9 +/- 10.4% in the thoracoscopy group (p = 0.021). Maximum oxygen uptake was similar, but dyspnea was the more common factor limiting exercise tolerance postoperatively in the thoracotomy group. Change in pre-to-postoperative performance status was 1.20 +/- 0.62 in the thoracotomy group and 0.55 +/- 0.51 in the thoracoscopy group (p = 0.0003). CONCLUSIONS: Thoracoscopic esophagectomy for esophageal cancer has better preservation of pulmonary function and quality-of-life.

Adult↗

PubMed1988

[Indications for coronary revascularization and the postoperative evaluations using Tl-201 exercise myocardial scintigraphy and a bull's eye display].

Tl-201 exercise myocardial scintigraphy and quantitative analysis using bull's eye display were performed in 31 cases (18 bypass cases, 13 PTCA cases) to determine the indications for coronary artery bypass surgery and PTCA, and to evaluate postoperative improvement. Regions of interest (ROI) corresponding to each revascularized area were created on a bull's eye display. Then the washout rates (WR) and % uptakes were expressed as percentages. Improvement was judged to have occurred if the revascularized coronary artery was patent and both the WR and % uptake returned to the normal range as determined from the examinations of 20 normal cases. The results were as follows: 1. The preoperative mean WR of the improved areas (30 vessels) was 19 +- 15%, while that of the unimproved areas (15 vessels) was 35 +- 7%. We assumed that the area was suitable for revascularization when the preoperative WR was less than 25% which was in the lower limit of the normal range. Then, 18 vessels were judged to be suitable for surgery, and subsequent postoperative improvement was obtained in the 17 areas. 2. In 32 scintigraphically-improved areas, 30 vessels were angiographically patent, while five vessels were obliterated angiographically in 13 scintigraphically-unimproved areas (diagnostic validity was 76% of all 45 vessels). 3. The exercise tolerance increased significantly (p less than 0.01) from 8.7 +- 2.0 min to 11.6 +- 2.5 min in the improved cases in which all the revascularized areas were improved after revascularization. There was no change of the exercise tolerance (before: 9.4 +- 3.4 min, after: 9.4 +- 2.5 min) in the unimproved cases in which all the revascularized areas were unimproved. 4. Quantitative analysis was useful for objective evaluation, because the visual evaluations did not always agree with the quantitative evaluation. We concluded that the area with the preoperative WR less than the normal range is suitable for revascularization. As the scintigraphic evaluation was in accord with improved exercise tolerance and with patency as observed by coronary angiography, our method seems useful for postoperative follow-up.

Angioplasty, Balloon↗

PubMed1992

Short-term reproducibility of gas exchange measurements during bicycle exercise in patients with mild to moderate congestive heart failure.

A series of 45 patients with congestive heart failure due to coronary disease had semisupine bicycle exercise tests (ramp protocol, 10 W/min) on two occasions separated by 3 to 7 days in order to determine the short-term reproducibility of gas exchange measurements during symptom-limited exercise. The percentage difference (PD) between each pair of measurements (m1, m2; PD = 100%.(m2-m1): m1) were calculated. The mean PD values (+/- 1 sigma) and the single determination standard deviations (SDSD) for exercise tolerance (ET, W), peak heart rate (pHR, 1/min), peak oxygen uptake (pVO2, ml/min/kg), peak carbon dioxide output (pVCO2, ml/min/kg), and peak minute ventilation (pVE, l/min) were as follows: [table: see text] No patient reached a plateau of oxygen uptake during the last portion of the ramp exercise test. Thus, pVO2 is not an objective endpoint. The single determination standard deviations show that exercise tolerance and peak oxygen uptake do not differ as to their reproducibility. The absolute values of PD were not a function of exercise tolerance for any of the parameters studied. The PD values for ET and pVO2 were normally distributed. The data suggest that a change in ET and pVO2 must exceed 27% and 28% between two sequential studies in an individual patient in order to be significant at the 5% level, respectively. For the one-tailed test situation, the changes in ET or pVO2 must be greater than 23% in order to be significant.

Adult↗

PubMed1988

Antianginal effects of intravenous nitroglycerin over 24 hours.

To determine the constancy of hemodynamic and antianginal effects of the constant infusion of intravenous nitroglycerin (NTG) and their relationship to infusion rate and plasma NTG concentration, we administered maximal tolerated doses of intravenous NTG (range 10 to 120 micrograms/min, mean = 52 +/- 33 micrograms/min) and placebo to 10 patients with chronic stable angina for 25 hr each in a randomized, double-blind fashion. Sublingual NTG (0.4 mg) was given at 24.5 hr of infusion as a positive control. Bicycle exercise time (NIH protocol), blood pressure, heart rate, exercise ST response, and venous plasma NTG were determined before and at 1, 4, 8, 24, and 24.5 hr. Plasma NTG was linearly related to infusion rate, reached a steady state within 15 min and was unchanged over 24 hr (mean = 5.5 +/- 1.2 ng/ml). Mean plasma NTG clearance was 9.3 liters/min. However, during dose titration, patients demonstrated different relationships between plasma NTG and hemodynamic effects, with widely varying slopes and intercepts. Intravenous NTG produced a sustained reduction in blood pressure and a rise in heart rate at rest, and a reduction in blood pressure during submaximal exercise at as late as 24 hr, associated with reduced submaximal ST segment abnormality. In contrast, exercise tolerance to onset of angina showed a marked initial increase on intravenous NTG but fell progressively and did not differ from that with placebo at 24 hr. Increased exercise tolerance was associated with an increase in maximal heart rate and double product (heart rate X blood pressure), suggesting that direct coronary vasodilation and/or reduced left ventricular volume were the principal determinants of increased exercise tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Sublingual↗

PubMed1987

A multicenter study of a new inotropic agent, piperanometozine (OPC-8212) in congestive heart failure: clinical improvement during short-term treatment.

Piperanometozine (OPC-8212) is a new, orally effective inotropic agent. To evaluate the efficacy of this agent on systemic hemodynamics and clinical symptoms in patients with congestive heart failure, a multicenter study was performed. Thirty four patients with New York Heart Association (NYHA) functional classes II to IV and initially treated with digitalis were enrolled from ten centers. After a washout period of one or two weeks (placebo period), digitalis was replaced by piperanometozine (30 or 60 mg/day) for four weeks, while other drugs were continued. Clinical symptoms, routine physical findings, electrocardiogram, chest roentgenogram, echocardiogram, exercise tolerance time, and routine laboratory data were obtained in 34 patients. Four patients were withdrawn from the study before completion. After the withdrawal of digitalis, heart rate was increased and ejection fraction was decreased. Exercise tolerance time was increased while other parameters were unchanged. At the end of the treatment period with piperanometozine, ejection fraction significantly (p less than 0.05) increased with a decrease in LV end-systolic volume (p less than 0.05), whereas heart rate and blood pressure remained unchanged. Systolic blood pressure/LV end-systolic volume (P/V index) tended to decrease after the withdrawal of digitalis and increase during piperanometozine therapy. Exercise tolerance time was further increased (p less than 0.01) and NYHA functional class was improved in 11 patients, whereas it worsened in only one patient. No major adverse effects were observed. These results indicate that a short-term therapy of oral piperanometozine restored the depressed cardiac performance of the heart and improved clinical symptoms in patients with congestive heart failure. Thus, this promising agent deserves further clinical study in long-term trials.

Aged↗

PubMed1999

Group psychological treatment for chest pain with normal coronary arteries.

We used a psychological treatment package (education, relaxation, breathing training, graded exposure to activity and exercise, and challenging automatic thoughts about heart disease) to treat 60 patients who had continuing chest pain despite cardiological reassurance following haemodynamically normal angiography. The treatment was delivered in six sessions over eight weeks to groups of up to six patients. The patients kept daily records of chest pain episode frequency and nitrate use. Questionnaires were used to assess anxiety, depression and disability. Exercise tolerance was tested by treadmill electrocardiography, with capnographic assessment of hyperventilation. The results were compared with waiting-list controls. Treatment significantly reduced chest pain episodes (p < 0.01) from median 6.5 to 2.5 per week. There were significant improvements in anxiety and depression scores (p < 0.05), disability rating (p < 0.0001) and exercise tolerance (p < 0.05), and these were maintained at six month follow-up. Treatment reduced the prevalence of hyperventilation from 54% to 34% (p < 0.01) but not the prevalence of ECG-positive exercise tests. Patients continuing to attribute their pain to heart disease had poorer outcomes. Group psychological treatment for non-cardiac chest pain is feasible, reduces pain, psychological morbidity and disability, and improves exercise tolerance.

Breathing Exercises↗

PubMed2003

[Clinical outcome of patients after transmyocardial laser revascularization alone and combined with coronary artery bypass grafting].

The aim of the study was to assess the effect of transmyocardial laser revascularization (TMLR) alone and in combination with coronary artery bypass grafting (CABG) on the angina score (CCS--Canadian Cardiovascular Society class), exercise tolerance and left ventricular function 6 months after the procedures. Sixty two patients were subjected to revascularization, 38 to sole TMLR procedure and 24 to combination CABG and TMLR (CABG/TMLR group). The angina score and exercise stress test together with radionuclide ventriculography were performed before and 6 months after the operation. The angina class and exercise tolerance were similar in both groups preoperatively. After the operation the improvement was seen in both groups with no statistical difference. The left ventricular ejection fraction were 61 +/- 8% and 54 +/- 8% (p < 0.05) before operation and after 6 months respectively. Transmyocardial laser revascularisation alone and in combination with coronary artery bypass grafting may relieve the angina and improve the exercise tolerance. However the left ventricular ejection fraction may drop significantly.

Coronary Artery Bypass↗

PubMed1984

Long-term captopril therapy for chronic congestive heart failure.

Although the short-term hemodynamic and clinical responses to angiotensin-converting enzyme inhibition in patients with congestive heart failure (CHF) are well known, little information is available about the long-term results of captopril therapy. In the present study, 15 stable outpatients received captopril therapy and were followed for a mean of 19 months (range 6 to 27) with serial clinical assessments and measurements of exercise tolerance, ejection fraction (EF) and cardiothoracic ratio. Exercise tolerance on a modified Naughton protocol improved from 10.5 +/- 2.7 to 12.7 +/- 2.4 minutes (mean +/- standard deviation) at 3 months (p less than 0.001), tended to increase progressively up to 12 months and remained significantly increased even after 24 months (9.7 +/- 1.8 vs 13.5 +/- 4.0 minutes, p less than 0.05). However, individual responses were variable; 4 patients did not show measurable improvement. Left ventricular EF increased from 0.20 +/- 0.06 to 0.25 +/- 0.06 (p less than 0.01) at 3 months and remained higher (0.30 +/- 0.12, p less than 0.02) at latest follow-up. Cardiothoracic ratio decreased from 0.59 +/- 0.04 to 0.56 +/- 0.05 (p less than 0.02) at 3 months and remained significantly lower at 12 months and at latest follow-up, although again individual responses were variable. Clinical responses generally correlated with these objective measurements, with clinical classification on a scale modified from the New York Heart Association classification improving from 3.0 +/- 0.6 to 2.3 +/- 0.5 (p less than 0.01) at 3 months and remaining improved throughout the follow-up period.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1991

Impaired exercise capacity in adults with moderate scoliosis.

We measured lung function and exercise tolerance in 15 adults with moderate kyphoscoliosis (thoracic curvatures between 25 degrees and 70 degrees, mean +/- SD = 46.93 degrees +/- 14.02 degrees). Forced vital capacity showed a slight reduction from values predicted from age and sex matched control subjects (3.39 +/- 1.06 vs 4.06 +/- 0.82 L, p less than 0.05). However, exercise tolerance was significantly lower than previously reported in healthy adults (VO2max = 31.60 +/- 9.12 vs 37.07 +/- 4.91 ml/kg/min, p less than 0.05). Despite the reduced exercise tolerance, the ratio of maximum tidal volume to vital capacity (VTmax/VC) was similar to that observed in healthy adults. The mean dyspnea index (VEmax/MVV) was also normal at 69.4 +/- 19.0. Hypoxic and hypercapnic ventilatory responses were within predicted normal limits at 0.67 +/- 0.37 L/min-1 fall in SaO2-1 and 1.67 +/- 0.92 L/min-1 mm Hg PCO2(-1). We conclude that the impairment of exercise performance found in adults with moderate scoliosis cannot be attributed to any important ventilatory limitation, abnormality in lung volume, or impaired chemoreceptor sensitivity. We suggest that the reduced VO2max likely arises from deconditioning and lack of regular aerobic exercise.

Adult↗

PubMed1989

Transtracheal oxygen decreases inspired minute ventilation.

Although patients using transtracheal oxygen (TTO2) frequently report decreased dyspnea and improved exercise tolerance, the mechanism for these effects is unknown. We hypothesized that these patients might have decreased inspired minute ventilation (VI), and this might be one mechanism for their decreased dyspnea and improved exercise tolerance. The effects of TTO2 on VI were studied in seven patients with chronic hypoxemia; two had chronic obstructive lung disease and five had severe restrictive disorders. VI, exhaled minute ventilation (VE), respiratory rate (RR), tidal volume (VT), earlobe O2 saturation (O2 sat), and arterial blood gases were measured while patients received varying amounts of oxygen either transtracheally or by mouth to achieve equivalent degrees of oxygenation. With TTO2 VI was reduced compared to VI with mouth O2 at similar levels of PaO2. As TTO2 flow rate increased, VI decreased; at 6 L/min O2 delivered transtracheally, mean VI was reduced by 54 +/- 7.0%. Reduction in VI was due to decreased VT; RR did not change. To determine if air delivered transtracheally decreased VI, five patients were studied while receiving air transtracheally or by mouth. With transtracheal air, VI was significantly less than VI obtained while breathing air by mouth. We conclude that VI is decreased when oxygen or air is delivered directly into the trachea and that VI decreases as transtracheal flow increases. This effect is not due solely to changes in oxygenation. Decreased dyspnea and improved exercise tolerance in patients using TTO2 may be due to decreased VI and decreased inspiratory work of breathing.

Adult↗

PubMed2003

Impact of serial changes in cardiac hemodynamics on exercise performance in patients with heart failure due to ischemic and nonischemic cardiomyopathy.

Although prior studies have examined the role of central and peripheral hemodynamics on exercise tolerance within populations of patients with heart failure, a clear relation between hemodynamics and exercise has not been demonstrated. This may be due to the inability to control for other factors that may influence exercise performance. To isolate the impact of hemodynamics on exercise, we studied the relation between changes in these factors within individual patients studied on 2 occasions. A consecutive series of 133 ambulatory patients with heart failure were evaluated on 2 separate occasions with right-sided cardiac catheterization and treadmill cardiopulmonary exercise testing. Linear regression models were constructed and correlation coefficients were determined to examine the relation between changes in hemodynamic variables and changes in exercise variables over time for each patient. A significant correlation between peak oxygen consumption (VO(2)) and pulmonary arterial wedge pressure was found for both the first (r = -0.316, p <0.001) and second (r = -0.183, p = 0.029) tests. A stronger inverse correlation between the change in pulmonary arterial wedge pressure and change in peak VO(2) was observed in the study patients (r = -0.470, p <0.001). Similar correlations were found between change in peak VO(2) and changes in pulmonary arterial pressures. Changes in left ventricular filling pressure influence exercise tolerance in patients with heart failure due to left ventricular systolic dysfunction. Interpretation of cardiopulmonary exercise testing for the purpose of determining cardiac transplantation eligibility will be improved with knowledge of left ventricular filling pressure.

Adolescent↗

PubMed1982

Clinical relevance of verapamil plasma levels in stable angina pectoris.

Plasma levels of verapamil and norverapamil were evaluated in 77 patients who received oral verapamiL for treatment of angina pectoris. There was a sixfold interpatient variation in verapamil plasma concentrations, but plasma concentrations were linearly related to doses of the drug (240 to 480 mg/day) in the same patient (r = 0.81). Plasma concentrations of norverapamil, the major active metabolite of verapamil, were similar to those of verapamil. Although verapamil produced a significant improvement in exercise tolerance in most patients, the increase in exercise time was not related to plasma levels of the drug; however, most patients with improvement had plasma levels exceeding 100 ng/ml. An increase in the dose of verapamil from 320 to 480 mg daily produced a substantial (71%) increase in plasma levels of the drug but no significant increase in exercise tolerance (4%). The average increase in the P-R interval with 480 mg of verapamil in these 77 patients was small (8%) (161 +/- 18 to 174 +/- 22 ms); on.y six patients had first-degree heart block. These minor effects on atrioventricular conduction were noted despite plasma verapamil concentrations in 76 patients that exceeded 100 ng/ml, a level that successfully converts supraventricular tachycardias after intravenous drug administration. We differences between the effects of oral and intravenous verapamil on atrioventricular conduction may be the result of stereoselective hepatic inactivation of verapamil's I-isomer. Determination of plasma levels of verapamil is of limited value in the management of patients with angina pectoris, but may be useful in the identification of nonresponders with plasma levels less than 100 ng/ml who may benefit from a further increment in drug dose.

Administration, Oral↗