Nonangiographic assessment of coronary artery bypass graft patency

Coronary artery bypass graft patency can be assessed using the indirect techniques of evaluating patients' symptoms and exercise tolerance, changes in stress electrocardiogram, radioisotope regional perfusion, and myocardial wall contraction. The direct techniques assess graft patency directly by visualizing grafts using conventional computed tomography (CT), ultrafast CT, magnetic resonance imaging, digital subtraction angiography, and echocardiography. The advantages and disadvantages of each of these modalities are reviewed. At the present time, ultrafast CT and possibly magnetic resonance imaging and Doppler appear to be the only techniques besides angiography that can consistently evaluate bypass graft patency. Although they have the advantage of being minimally invasive, they cannot show graft stenosis or sequential graft patency. These techniques are best used in following patients after coronary bypass graft surgery and ruling out graft closure as the source of chest pain.

The effects of rate responsive pacing on exercise performance in the postoperative univentricular heart

Following the Fontan operation for definitive palliation of the univentricular heart, sinus node dysfunction, and/or atrioventricular block requiring pacemaker therapy is common. In previous studies ventricular rate responsive pacing (VVI,R) resulted in improved exercise performance over VVI pacing in anatomically normal hearts with either sinus node disease or atrioventricular block. In this study, the usefulness of both VVI,R and DDD,R pacing are evaluated in the postoperative univentricular heart following the Fontan operation. Eight postoperative Fontan patients with sinus node disease or atrioventricular block underwent exercise testing using a treadmill protocol. Six patients had single chamber ventricular pacemakers and two patients had dual chambered rate responsive pacemakers. Median age at exercise testing was 14 years. Patients were tested in the VVI, VVI,R, and DDD,R modes acting as their own controls. Heart rate, work rate, oxygen consumption, and respiratory exchange ratio were monitored continuously. Heart rate was significantly increased in the rate responsive modes compared to the VVI mode. In spite of the significant increase in heart rate, there was no change in maximal work rate or oxygen consumption. There was also no significant change in oxygen consumption at ventilatory anaerobic threshold. From these data we would conclude that VVI,R pacing in postoperative univentricular hearts does not result in improved exercise performance and that further study with DDD,R pacing is needed to determine its usefulness in this group of patients.

Hemodynamic determinants of exercise capacity in chronic atrial fibrillation

To evaluate the response of patients with chronic atrial fibrillation (AF) to exercise, 79 male patients (mean age 64 +/- 1 years) with AF underwent resting two-dimensional and M-mode echocardiography and symptom-limited treadmill testing with ventilatory gas exchange analysis. Patients were classified by underlying disease into five subgroups: no underlying disease (LONE: n = 17), hypertension (HT: n = 11), ischemic heart disease (n = 13), cardiomyopathy or history of congestive heart failure (CHF: n = 26), and valvular disease (n = 12). A higher maximal heart rate than expected for age was observed (175 vs 157 beats/min), which was most notable in the LONE and HT subgroups. Maximal oxygen uptake (VO2 max) was lower than expected for age in all groups. Patients with CHF had a lower resting ejection fraction than all other patients (p < 0.001), a lower VO2 max, and a lower maximal heart rate than LONE and HT patients (p < 0.001). Stepwise regression analysis demonstrated that echocardiographic measurements at rest were poor predictors of VO2 max and VO2 at the ventilatory threshold. Among clinical, morphologic, and exercise variables, maximal systolic blood pressure accounted for the greatest variance in exercise capacity, but it explained only 35%. In patients with AF the higher than predicted maximal heart rates may be a compensatory mechanism for maintaining exercise capacity after the loss of normal atrial function. However, even in the absence of underlying disease, it does not appear to compensate fully for a compromised exercise capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Central and peripheral haemodynamic determinants of effort tolerance in patients with heart failure

We studied central and peripheral hemodynamics and exercise tolerance in 24 patients with left ventricular dysfunction. All were in NYHA class II or III, and echocardiographic left ventricular ejection fraction was < 35% without pharmacologic influences. Patients underwent to treadmill test (Naughton protocol), cardiopulmonary upright bicycle test, and supine bicycle test with haemodynamic measurements. All tests were exhaustive. Average exercise time was 9 +/- 3.4 min, (range 3-20). Average ejection fraction (.28 +/- 0.65) dis not correlate with working capacity (r = .32), nor did left ventricular filling pressure (pulmonary capillary wedge pressure) at rest and at peak exercise (r = .29 and r = .02). Stroke volume and stroke volume index were on average depressed, with no variations during work; cardiac output and cardiac index were also depressed, with a significant increase at peak exercise (both p < .001). Systemic and pulmonary resistances were increased, but systemic resistances tended to decrease during effort (p < .001), while pulmonary resistances did not (p = NS). We subdivided patients according to systemic vascular resistances lower or higher than 1500 dynes.cm.sec-5 at rest; this identifies two different working capacities (low systemic vascular resistances 11.7 +/- 4.4 min, high systemic vascular resistances 6.9 +/- 3.2 min, p < .05). Patients were then divided in two groups: group I (rest stroke volume > 60 ml) and group II (rest stroke volume < 60 ml). Group I worked 11 +/- 5 min, group II 8.5 +/- 3 min (p < .05). We performed a linear regression analysis between cardiac output and systemic vascular resistances at rest and during exercise in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a standardized meal on the threshold of exercise-induced myocardial ischemia in patients with stable angina

OBJECTIVES

This study was undertaken to determine the effect of a standardized meal on the ischemic threshold and exercise capacity in a series of 20 patients with stable angina, exercise-induced ischemia and reversible exercise-induced perfusion defects.

BACKGROUND

It is generally accepted that exercise tolerance in patients with angina is reduced after a meal. However, studies that have addressed this phenomenon have yielded results that are contradictory and inconclusive.

METHODS

Two exercise tests using the Bruce protocol with technetium-99m (99mTc)-sestamibi were performed on consecutive days in a randomized order. One test was performed in the fasting state and the other 30 min after a 1,000-calorie meal.

RESULTS

In the postprandial state, exercise time to ischemia was reduced by 20% from 248 +/- 93 s to 197 +/- 87 s (p = 0.0007), time to angina by 15% from 340 +/- 82 s to 287 +/- 94 s (p = 0.002) and exercise tolerance by 9% from 376 +/- 65 s to 344 +/- 86 s (p = 0.002). Rate-pressure products at these exercise test end points were not significantly different in the fasting and postprandial tests, and the quantitative 99mTc-sestamibi ischemia score was unchanged.

CONCLUSIONS

In patients with stable angina, a 1,000-calorie meal significantly reduced time to ischemia, time to angina and exercise tolerance because of a more rapid increase in myocardial oxygen demand with exercise. The extent and severity of exercise-induced ischemia were unchanged.

Importance of abnormal lung perfusion in excessive exercise ventilation in chronic heart failure

Whether excessive ventilatory response to exercise is related to the maldistribution of pulmonary blood flow was examined in 23 patients with chronic heart failure and nine age-matched normal subjects. With the use of technetium 99m macroaggregated albumin, the resting distribution of pulmonary blood flow was assessed by the scintigraphic counts ratio of upper to lower lung fields. The ventilatory response to exercise was assessed by the slope of the relationship between minute ventilation and carbon dioxide production during exercise. Eight patients (group A) had slope less than 33, the upper limit of the normal range, and 15 patients had slope of 33 or greater (group B). In group B pulmonary blood flow was distributed more to the upper lung, which made the counts ratio (60%) higher than in normal subjects (34%) or in patients in group A (38%). There was no significant difference in pulmonary flow distribution between normal subjects and patients in group A. In group B tidal volume did not increase during exercise as much as it did in normal subjects and in patients in group A; therefore, the respiratory pattern was rapid and shallow. Although the ratio of physiologic dead space to tidal volume fell by 20% during exercise in normal subjects and by 23% in patients in group A, it failed to decrease in patients in group B (-1%), which indicates a relative increase in dead space respiration during exercise. These data indicate that decreased lung compliance and regional ventilation-perfusion mismatch caused by pulmonary vascular and parenchymal abnormalities would play an important role in the excessive exercise ventilation in chronic heart failure.

Effects of buspirone on anxiety levels and exercise tolerance in patients with chronic airflow obstruction and mild anxiety

The objective of this study was to determine if buspirone would alleviate anxiety and improve exercise tolerance of anxious patients with chronic airflow obstruction (CAO). Eleven male patients with mild to moderate anxiety and CAO completed this study comparing buspirone, 10 to 20 mg given three times a day, with placebo. Patients were evaluated with State Trait Anxiety Inventory, spirometry, 12-min walk, incremental exercise on a cycle ergometer to symptom limitation and measurement of dyspnea with a modified Borg scale at exercise levels and the end of each 2 min on 12-min walk. There were no significant differences in anxiety scores, work load, maximum oxygen consumption per minute, maximum expired volume per minute, PETCO2, PETO2, 12-min walking distance or dyspnea scores after 6 weeks of buspirone or placebo therapy. We conclude that administration of buspirone has no significant effect on anxiety levels, exercise capabilities or PETO2 or PETCO2 in patients with CAO and mild anxiety.

Altered exercise gas exchange and cardiac function in patients with mild chronic obstructive pulmonary disease

Patients with advanced COPD have significantly reduced gas exchange and pulmonary function; however, little is known regarding physical work capacity and exercise gas exchange in patients with mild COPD. A total of 39 individuals (20 men and 19 women) without evidence of COPD (controls) and 51 individuals (29 men and 22 women) with mild COPD (FEV1 > or = 60 percent of predicted; and ratio of FEV1 over forced vital capacity of 60 to 70 percent) were tested to determine resting pulmonary function and resting and peak exercise gas exchange in response to progressive maximal cycle ergometer testing. In general, those with mild COPD had similar smoking histories and essentially equivalent resting gas exchange studies as compared to the controls. Measured maximal oxygen consumption was less in both the male (p < 0.003) and the female patients (p < 0.001). This was due, in part, to a lower maximal ventilation in the men with obstruction (p < 0.04), resulting from a significant reduction in tidal volume (p < 0.05). Women presented with similar decreases in maximal ventilation (p < 0.04) and maximal tidal volume (p < 0.01), while no difference in maximal respiratory rate was noted in either group (p > 0.05). Breathing reserve was 32 percent and 53 percent less for the male and female patients with obstruction than for controls. Maximal heart rates were less in the individuals with obstruction, where they reached 93 percent (p < 0.02) and 96 percent (p < 0.003) of the age- and sex-specific maximal heart rates for men and women as compared to 101 percent and 99 percent obtained in the controls. Achieved absolute work loads for men and women (in kilogram.meters per minute) were lower in the groups with obstruction (p < 0.002 and 0.0003) as well. These results demonstrate that work capacity and gas exchange are significantly decreased in individuals with even mild COPD. The reduction in functional work capacity is secondary to a loss of pulmonary function, as well as chronic deconditioning. Increased dyspnea may be responsible for the premature cessation of exercise observed in patients with mild COPD. Thus, early intervention with exercise training may be warranted to counter the deleterious effects of deconditioning and declining pulmonary function in patients with mild COPD.

Prediction of exercise tolerance in the chronic phase of myocardial infarction by using ventilatory gas analysis

To predict exercise tolerance in the chronic phase of myocardial infarction (MI), cardiopulmonary exercise testing was performed using a ramp treadmill protocol in 25 patients at 1 and 3 months after the onset of MI. Oxygen uptake, heart rate and O2 pulse were estimated at rest, during a warm-up period, and at the levels of anaerobic threshold (AT), respiratory compensation (RC) and peak exercise. Results were as follows: 1) AT and peak oxygen uptake at 3 months after the onset of MI were 14.1 +/- 2.8 and 21.8 +/- 5.2 ml/min/Kg, respectively. 2) The subjects were divided into 2 groups according to peak oxygen uptake at 3 months: one showing peak oxygen uptake > 22 ml/min/Kg and the other < 22 ml/min/Kg. The former group (n = 13) was referred to as the good tolerance group, and the latter group (n = 12) was referred to as the poor tolerance group. Oxygen uptake at AT, RC and peak exercise was lower in the poor tolerance group than in the good tolerance group (11.2 vs 14.7, 15.1 vs 20.4, 17.1 vs 23.4 ml/min/Kg, respectively). 3) The increases in oxygen uptake from AT to RC and from AT to peak exercise were less in the poor tolerance group than in the good tolerance group. 4) O2 pulse at rest, warm-up, AT, RC and peak exercise were also lower in the poor tolerance group.2+ tolerance in the chronic phase of MI.

[Respiratory symptoms and pulmonary function in O' Higgins antarctic base residents]

The aim was to study pulmonary function and physical capacity and their relation to respiratory symptoms among military personnel before and after one year of permanence in an Antarctic base. In 21 men aged 38 +/- 5.5 years, enquiries about smoking habits and respiratory symptoms, spirometry, bronchial provocation test and measures of aerobic capacity and peak expiratory flow were performed. After 75 days of permanence in the base, there was a significant increase in weight, exertional dyspnea appeared in 8 subjects and there was an 8.4% decrease in aerobic capacity. The bronchial provocation test was positive outdoors in 7 of the 21 staff members; when performed indoors, no subject had a positive test and in Santiago only one subject had a positive test (Chi sq p < 0.025). After 7.5 and 11 months of permanence, forced vital capacity decreased in 13% and no diurnal differences of peak expiratory flow were observed. In conclusion, the permanence in Antarctica may slightly affect the respiratory system with the appearance of exertional dyspnea and outdoor airway hyper reactivity in some residents.

Does cold air affect exercise capacity and dyspnea in stable chronic obstructive pulmonary disease?

Cold air may worsen asthmatic bronchoconstriction but can lessen breathlessness in normal individuals. Patients with COPD sometimes report improvement in their dyspnea in cold weather. We examined the effect of breathing cold air on exercise tolerance and the perception of breathlessness in 19 patients with stable COPD (age [+/- SD], 63 +/- 6 years; FEV1, 0.99 +/- 0.28 L) in a randomized open study. Patients exercised on a cycle ergometer breathing either room or cold air (-13 degrees C), breathlessness being assessed by Borg scaling. Peak exercise performance improved when breathing cold air (mean +/- SE), 46 +/- 6 W compared with 37 +/- 7 W (p < 0.05) while end-exercise breathlessness fell from 4.6 +/- 0.4 compared with 4.1 +/- 0.5 (p < 0.05) when breathing cold air. End-exercise ETCO2 was higher breathing cold air (6.1 +/- 0.3 kPa compared with 5.5 +/- 0.3 kPa) (p < 0.005). There was no difference in breathlessness at equivalent levels of ventilation. Cold air reduces breathlessness in COPD, probably by inducing relative hypoventilation.

Cardiopulmonary exercise testing in syndrome X

Patients with syndrome X have been found to have an abnormal coronary blood flow reserve. The physical performance during exercise, however, has been incompletely investigated. Cardiopulmonary exercise testing (CPX) is a reliable noninvasive method to provide indexes of lung, heart, circulation, and muscle functions. In 15 patients (10 women) with syndrome X and in age and sex-matched normal individuals, CPX was performed twice a day (8 AM and 4 PM) on two separate occasions 2 months apart. Time and oxygen consumption at peak exercise, at ventilatory anaerobic and electrocardiographic thresholds, as well as norepinephrine plasma concentrations at each work load and at peak exercise in both tests were obtained. In syndrome X in both evaluations, the 4 PM performance was characterized by an earlier onset of both ventilatory anaerobic and electrocardiographic thresholds despite lower values of VO2 and double-product, and by a greater peak ST segment depression despite similar total exercise time, VO2, and double-product. No difference between tests was found in the norepinephrine response to exercise. Normal subjects showed reproducible CPX and hormonal responses in the two tests. Thus these data may suggest a circadian variation of coronary vascular response to exercise in patients with syndrome X, leading to a lower ischemic threshold early in the afternoon. The parallel earlier onset of the ventilatory anaerobic threshold may reflect a concomitant abnormal muscular blood flow response (that is, vasoconstriction of working muscle arteries), suggesting a link between coronary and peripheral circulations.

Pulmonary and peripheral vascular factors are important determinants of peak exercise oxygen uptake in patients with heart failure

OBJECTIVES

This study was conducted to determine the relations among exercise capacity and pulmonary, peripheral vascular, cardiac and neurohormonal factors in patients with chronic heart failure.

BACKGROUND

The mechanisms of exercise intolerance in heart failure have not been fully clarified. Previous studies have indicated that peripheral factors such as regional blood flow may be more closely associated with exercise capacity than cardiac function, whereas the role of pulmonary function has received less attention.

METHODS

Fifty patients with stable heart failure underwent a comprehensive assessment that included a symptom-limited maximal cardiopulmonary exercise test, right heart catheterization, pulmonary function tests, neurohormonal levels, radionuclide ventriculography and forearm blood flow at rest and after 5 min of brachial artery occlusion. Univariate and stepwise linear regression analyses were used to relate peak exercise oxygen uptake to indexes of cardiac, peripheral vascular, pulmonary and neurohormonal factors both alone and in combination.

RESULTS

The mean ejection fraction was 19% and peak oxygen uptake was 16.5 ml/min per kg in this group of patients. By univariate analysis, there were no significant correlations between peak oxygen uptake and rest cardiac output, pulmonary wedge pressure, ejection fraction and pulmonary or systemic vascular resistance. In contrast, even in the absence of arterial desaturation during exercise, the forced expiratory volume in 1 s (r = 0.55, p < 0.001), forced vital capacity (r = 0.46, p < 0.01) and diffusing capacity for carbon monoxide (r = 0.47, p < 0.01) were all significantly associated with peak oxygen uptake. Peak postocclusion forearm blood flow (r = 0.45, p < 0.01), the corresponding minimal forearm vascular resistance (r = -0.56; p < 0.01) and plasma norepinephrine level at rest (r = -0.45; p < 0.01) were also significantly correlated with peak oxygen uptake. By multivariate analysis, minimal forearm vascular resistance and forced expiratory volume in 1 s were shown to be independently related to peak oxygen uptake, with a combined R value of 0.71. Other two-variate models included forced expiratory volume and plasma norepinephrine (R = 0.67) and forced expiratory volume and diffusing capacity (R = 0.65). Because forced vital capacity was highly correlated with forced expiratory volume in 1 s, it could be combined with the same variables to yield similar R values. Addition of any third variable did not improve these correlations.

CONCLUSIONS

In comparison with rest indexes of cardiac performance, measures of pulmonary function and peripheral vasodilator capacity were more closely associated with peak exercise oxygen uptake in patients with heart failure. Furthermore, the associations were independent of each other and together accounted for 50% of the variance in peak oxygen uptake. These data suggest that pulmonary and peripheral vascular adaptations may be important determinants of exercise intolerance in heart failure.

The effect of chordal preservation on late outcome after mitral valve replacement: a randomized study

Postoperative survival, hemodynamic status and exercise tolerance with or without posterior chordal preservation were compared in a case-limited prospective randomized manner in 100 patients who underwent isolated mitral valve replacement with size 29mm or 31mm St. Jude Medical prostheses. The preoperative clinical and hemodynamic parameters were comparable in the two groups. The mean follow up was 293.3 months for those with and 263.1 months for patients without chordal preservation. Right heart cardiac catheterization was performed in every patients at the end of the follow up period and it demonstrated significantly better results with than without chordal preservation (cardiac index 2.81 +/- 0.47 vs. 2.63 +/- 0.52, p < 0.05; pulmonary arterial pressure 30 +/- 11 mmHg vs. 37 +/- 13 mmHg at 30 Watts bicycle exercise, p < 0.01; end-diastolic volume index 75 +/- 22 vs. 86 +/- 38 ml/m2, p < 0.02; and maximum exercise tolerance 1.8 +/- 0.3 vs. 1.2 +/- 0.5 Watt/kg, p < 0.01). Actuarial freedom from complications was 78.1 +/- 4.2% with and 70.7 +/- 6.2% without chordal preservation (p < 0.02). In particular, patients with severe mitral regurgitation benefited from the preservation of the posterior mitral leaflet with its chordal and papillary structure (p < 0.001).

Nasal continuous positive airway pressure in chronic heart failure with sleep-disordered breathing

Nasal continuous positive airway pressure (NCPAP) has been reported to improve daytime symptoms in patients with sleep disordered breathing due to heart failure. To examine this in a controlled manner, eight men with stable chronic heart failure (mean left ventricular ejection fraction 18% and mean frusemide dose 160 mg) were entered into a controlled trial of domiciliary nocturnal NCPAP. At polysomnography (with sleep apnea quantified as the number of > 4% dips in arterial saturation per hour), seven had nocturnal Cheyne-Stokes respiration (SaO2 dip rate 3 to 27/hr), and one both central and obstructive apneas (SaO2 dip rate 8/hr). After 2 wk nocturnal domiciliary NCPAP at < 1.5 cm H2O (placebo) and 7.5 cm H2O (active) in random order, bicycle exercise tolerance and heart failure symptoms (modified Likert questionnaire) were assessed by an observer unaware of the patients' NCPAP status. Pulse oximetry (all subjects) and radionuclide estimated left ventricular ejection fraction (three subjects) were also measured at the end of each period. Two subjects withdrew from the study because of worsening heart failure during active NCPAP (7.5 cm H2O), and one of these subjects died. In the remaining six subjects exercise tolerance, symptom scores, and the severity of sleep apnea were similar on active NCPAP compared with placebo. When it was measured, resting left ventricular ejection fraction was lower on active therapy than on placebo. These data exclude a 25% improvement in exercise tolerance with 95% confidence and suggest that a study of 160 subjects would be needed to exclude a 10% change in symptom score.(ABSTRACT TRUNCATED AT 250 WORDS)

Transdermal nitroglycerin reduces the frequency of anginal attacks but fails to prevent silent ischemia

OBJECTIVES

The aim of this study was to objectively evaluate the effects of intermittent administration of transdermal nitroglycerin on effort tolerance, frequency of anginal attacks and presence of silent ischemic events that occur during normal daily activities.

BACKGROUND

Previous studies have shown that transdermal nitroglycerin patches reduce the incidence of anginal attacks and improve exercise capacity when given intermittently. However, no carefully controlled studies are available on the effects of these preparations (and their dosing schedule) on the occurrence of "silent" ischemic events during unrestricted daily activities.

METHODS

Twelve men with chronic stable angina, a positive exercise test result and significant coronary artery disease completed a randomized, double-blind, placebo-controlled trial in which patches were worn either continuously or with overnight (8 h) removal. The effects of treatment were objectively assessed by both treadmill exercise testing and 24-h ambulatory electrocardiographic monitoring.

RESULTS

Only the intermittent dosing schedule afforded a small but significant improvement in exercise tolerance and prolonged exercise duration and time to ST segment depression. The frequency of anginal attacks was also reduced by both the continuous and intermittent treatment, but the effects on symptoms were not paralleled by a concomitant reduction in ischemic episodes recorded during ambulatory monitoring.

CONCLUSIONS

The results indicate that when used as monotherapy, intermittent transdermal nitroglycerin preparations lessen symptoms but are ineffective for the long-term prophylaxis of silent myocardial ischemia.

Relative importance of psychologic traits and severity of ischemia in causing angina during treadmill exercise. Canadian Amlodipine/Atenolol in Silent Ischemia Study (CASIS) Investigators

OBJECTIVES

This study was conducted to compare the influence of psychologic traits versus ischemia severity on the occurrence of angina during treadmill exercise.

BACKGROUND

Some studies suggest that angina is associated with certain psychologic traits, whereas others show an association with more severe ischemia. The relative influence of these two factors and the extent to which they interact are not known.

METHODS

Off-drug treadmill exercise testing and a battery of psychologic tests were performed on 122 patients with known coronary artery disease. Psychologic tests measured sensitivity to physical symptoms, denial and deception, type A behavior, anger, hostility, depression, marital adjustment and amount of external stress. Stepwise logistic regression was used to determine the independent association of psychologic traits, ischemic threshold and exercise tolerance with the occurrence of angina.

RESULTS

Angina during treadmill exercise was reported by 66 of 122 patients. On univariate testing, angina was positively associated with sensitivity to physical symptoms (p < 0.001), type A behavior (p = 0.021) and depression (p = 0.032) and was negatively associated with exercise tolerance (p < 0.001) and work load threshold for ischemia (p < 0.01). Multivariate analysis revealed independent and additive associations of angina with sensitivity to physical symptoms (p = 0.003), exercise capacity (p = 0.003) and work load threshold for ischemia (p = 0.018). Once these were included in a logistic model, depression and type A behavior were no longer significant. Other psychologic traits showed no association with angina.

CONCLUSIONS

Sensitivity to physical symptoms, ischemic threshold and exercise tolerance are independently associated with angina, with sensitivity to physical symptoms having the stronger influence. The physiologic and psychologic mechanisms underlying symptom perception have an influence on angina that is independent of and additive to the severity of underlying ischemia.

Serial evaluation of left ventricular function by radionuclide ventriculography at rest and during exercise after orthotopic heart transplantation

Discrepant results have previously been reported concerning long-term left ventricular function in the human transplanted heart as assessed by radionuclide ventriculography. In this study, radionuclide ventriculograms were obtained at rest and during exercise in 19 patients < 6 months, 7-12 months, 13-24 months and > 24 months after transplantation. Ejection fraction decreased significantly from < 6 months to 13-24 months after transplantation (rest: 69.1% +/- 9.7% to 56.7% +/- 8.3%, P < 0.05; exercise: 70.4% +/- 11.3% to 59% +/- 8%, P < 0.05). Heart rate increased significantly during exercise after > 2 years (90.2 +/- 10.5 beats/min to 103.5 +/- 15 beats/min, P < 0.05) but not within 6 months after transplantation (98.5 +/- 12.8 beats/min to 99.07 +/- 15.8 beats/min). Left ventricular end-diastolic volume remained unchanged. Peak filling rate at rest decreased significantly from 4.2 +/- 0.96 edv/s < 6 months after transplantation to 3.3 +/- 0.66 edv/s (P < 0.05) 13-24 months and 3.3 +/- 0.64 edv/s (P < 0.05) > 24 months after cardiac transplantation. Exercise peak filing rate did not change significantly. It is concluded that radionuclide ventriculography demonstrates a decrease in systolic left ventricular function in the long-term course after cardiac transplantation. A significant increase in exercise peak heart rate may be due to autonomic reinnervation. Differences in the literature concerning left ventricular function may be due to different observation intervals following cardiac transplantation.

Atrial adaptive rate pacing in sick sinus syndrome: effects on exercise capacity and arrhythmias

OBJECTIVE

To test the hypotheses that adaptive rate atrial (AAIR) pacing: significantly increases maximal exercise capacity, and results in significant suppression of supraventricular and ventricular arrhythmia compared with fixed rate atrial (AAI) pacing.

DESIGN

Prospective, randomised, single blind, crossover study with maximal treadmill exercise testing and 24 hour ambulatory electrocardiographic monitoring in AAIR and AAI modes.

SETTING

Regional pacing centre.

PATIENTS

30 consecutive patients (mean SD age 65 (12) years) with sick sinus syndrome who required permanent pacing, without evidence of conduction disturbance on 12 lead electrocardiograms or 24 hour ambulatory electrocardiographic monitoring and without other cardiovascular or systemic disease.

INTERVENTIONS

Activity sensing or minute ventilation driven systems (AAI/AAIR) were implanted alternately.

RESULTS

The mean (SD) peak heart rate in AAI mode was 122(28)v 130(22) in AAIR mode (p < 0.02) for the whole group and 104(17) v 120(5) (p < 0.003) for the patients with chronotropic incompetence. Exercise time was 12.3 (4.1) minutes in AAI and 12.3 (3.8) minutes in AAIR mode (NS) in the chronotropically incompetent patients. There were no significant differences in the Borg scores at peak exercise in AAI v AAIR mode in either group. The frequency per hour of atrial and ventricular arrhythmias showed no significant differences between the two modes in either the group as a whole or in the subgroups with chronotropic incompetence.

CONCLUSION

AAIR pacing confers little benefit in sick sinus syndrome compared with AAI pacing.

Transient myocardial ischemia after a first acute myocardial infarction and its relation to clinical characteristics, predischarge exercise testing and cardiac events at one-year follow-up

The relation between early out-of-hospital ambulatory ST-segment monitoring, clinical characteristics, predischarge maximal exercise testing and cardiac events was determined in 123 consecutive men (age 55 +/- 8 years) with a first acute myocardial infarction (AMI). During 36 hours of ambulatory recording 11 +/- 5 days after AMI 23 patients (19%) had 123 ischemic episodes (group 1), whereas 100 patients demonstrated no ischemia (group 2). Exercise-induced ST-segment depression was more prevalent in group 1 (83%) than in group 2 (47%) (p < 0.005). Group 1 patients also had more severe ischemia as judged from a shorter exercise duration before significant ST-segment depression (5.5 +/- 2.4 vs 7.7 +/- 4.1 minutes; p < 0.03) and more pronounced ST-segment depression on exercise testing (4.1 +/- 2.6 vs 2.6 +/- 1.6 mm; p < 0.03). Furthermore, exercise test results revealed an impaired hemodynamic response in group 1 compared with group 2: systolic blood pressure at maximal work load 160 +/- 31 vs 176 +/- 28 mm Hg (p < 0.025) and systolic blood pressure increase during exercise 41 +/- 24 vs 56 +/- 22 mm Hg (p < 0.01). With-in 368 +/- 8 days of follow-up the frequency of cardiac events (cardiac death, nonfatal reinfarction, and severe angina including the need of revascularization) was 52% in group 1 compared with 22% in group 2 (p < 0.01). Exercise-induced ischemia did not predict an adverse outcome: event rate 30 vs 25% in patients without residual ischemia (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of treatment strategy on predischarge exercise test in the Thrombolysis in Myocardial Infarction (TIMI) II Trial

Predischarge supine bicycle ergometry was used to assess persistent myocardial ischemia in postinfarction patients who received thrombolytic therapy and were randomized to an invasive versus conservative strategy in the Thrombolysis in Myocardial Infarction (TIMI) II trial. The frequency of ischemic responses in both strategies, and the 1-year prognostic importance of the different exercise test outcomes were examined. At 14 days, the percentage of patients with any adverse outcome (including death, presence of exercise-induced ST-segment depression, or inability to perform the exercise test) was 33.7% of 1,681 randomly assigned to the invasive strategy compared with 34.6% of 1,658 randomly assigned to the conservative strategy (p = 0.57). The 1-year mortality was greater in patients who did not perform the predischarge exercise test (7.7%) than in those who did (1.8%) (p < 0.001); the former were older, and a greater proportion were women, had a more frequent history of myocardial infarction, and more extensive coronary artery disease (p < 0.01 for each comparison). The 1-year mortality in patients with exercise-induced ST-segment depression or chest pain was only 1.4% (3 of 22) among those randomly assigned to the conservative strategy where coronary angiography and revascularization were recommended if the test result was abnormal (relative risk compared with those without ST-segment depression or chest pain 0.6; 99% confidence interval 0.1 to 2.9).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of exercise capacity in asthmatic children with various degrees of activity

Physical fitness in a group of 49 stable asthmatic children was determined by an incremental exercise test. Thirty-one normal children served as a control group. The asthmatic children were divided into three groups. Group 1 was comprised of 16 children who actively participated in organized sports, Group 2 of 16 children who did not participate in organized sports but who engaged in free-play, and Group 3 of 17 children with a sedentary life-style who avoided even free-play. The results of cardiopulmonary evaluation before and after maximal incremental exercise testing have shown that Groups 1 and 2 behaved like the control group and their physical fitness was similar. Group 3 whose life-style was sedentary had poor physical fitness as compared to the other asthmatics and to the control group. This was the result of poor cardiovascular conditioning and was unrelated to the respiratory limitation. We conclude that poor physical fitness in asthmatic children is the result of a sedentary life-style and can be potentially normalized.

Angina pectoris caused by dynamic exercise in hypertrophic cardiomyopathy with normal coronary arteries

To evaluate the relationship between angina pectoris caused by dynamic exercise and the time course of heart rate (HR) and hemodynamics during dynamic exercise in 15 patients with hypertrophic cardiomyopathy (HCM) with normal epicardial coronary arteries, the supine ergometer exercise test was performed during cardiac catheterization. The HCM patients were divided into a chest pain group (n = 6) and a no chest pain group (n = 9) based upon the results of the ergometer exercise test. There was no significant difference in the level of ST-segment depression after exercise in both the chest pain and no chest pain groups (-2.1 +/- 0.6 mm vs -2.6 +/- 1.1 mm, NS). Increase in heart rate (HR) and left ventricular end-diastolic pressure (LVEDP) in the early phase of the exercise test was significantly greater in the chest pain group compared with the no chest pain group. These observations suggest that in HCM patients, the occurrence of exertional chest pain has a close relationship with the rapid increase in HR and LVEDP in the early phase of dynamic exercise, but does not have a relationship with the gradual increase in these parameters.

Exercise intolerance in patients with McArdle's disease or mitochondrial myopathies

OBJECTIVES

To assess respiratory and metabolic adaptations in patients with phosphorylase deficiency and mitochondrial myopathies using maximal exercise tests.

PATIENTS AND METHODS

Five patients with McArdle's disease and five patients with mitochondrial myopathies performed the same incremental maximal exercise test. Their respiratory gas exchanges and the variation of the venous blood metabolites--lactate (LACT), pyruvate (PYR), alanine (ALA), ammonia (NH3)--were studied in comparison with the results of fourteen control subjects who performed the same test.

RESULTS

Compared with controls, the two groups of patients displayed a similar significant decrease of their maximal VO2. In McArdle's patients the limitation of the maximal oxygen consumption was associated with a low respiratory exchange ratio (RER), a high VE/VO2, and characteristic metabolic data: no rise of LACT and PYR, a decrease of ALA and an important rise of NH3. In mitochondrial myopathies low VO2 max were due to a leftwards shift, i.e. towards low powers of exercise, of LACT, PYR, NH3 and ALA values. However the pattern of increase of LACT, PYR and NH3, exponential, and of ALA, linear, as well as respiratory exchange ratios were similar to control values. In this case, the limitation of oxygen consumption was due to a lack of the usual substrate, pyruvate. Low respiratory exchange ratio demonstrated that the muscle metabolism had a tendency to shift to lipid oxidation.

CONCLUSION

These results suggest that patients with McArdle's disease may improve their muscle energy production by endurance training which enhances lipid metabolism, whereas in mitochondrial myopathies, the energy production by oxidation of pyruvate or lipids may be improved only by enzymatic substitution.

[Pulmonary function and exercise tolerance in patients treated with bone marrow transplantation (BMT)]

We assessed pulmonary function and exercise tolerance in 10 BMT patients. Their underlying disorders were as follows; chronic myeloid leukemia 5 cases, acute lymphoblastic leukemia 2 cases, aplastic anemia, acute myeloid leukemia and non-Hodgkin's lymphoma one case each. Their mean age was 26 +/- 9 years old. When the patients were healthy and free of serious complications and anemia, arterial blood gas examination, pulmonary function tests and incremental treadmill exercise test were examined repeatedly. Although %VC and FEV1.0% kept within normal range, PaO2 at rest, %DLCO, VO2max, VO2max/kg and O2-pulsemax remained low at one year after BMT. There were significant correlations between VO2max and O2-pulsemax [r = 0.955 (p < 0.001)], %VC [r = 0.758 (p < 0.02)], VE/VO2max [r = -0.749 (p < 0.02)] and delta SaO2/VO2/kg [r = -0.731 (p < 0.02)], suggesting that exercise intolerance in BMT patients may be based on both cardiac and gas exchange abnormalities. To evaluate cardiac dysfunction, we compared exercise parameters obtained at an exercise level of 75% predicted heart rate max in five age-matched normal subjects to those in six BMT patients who did not demonstrate desaturation during exercise. As a result, the mean values of VO2max/kg and O2-pulse/m2 in BMT patients were significantly lower than those in normal subjects, suggesting that cardiac dysfunction may be due to insufficiency of stroke volume during exercise. It is concluded that exercise intolerance in BMT patients may be mainly due to cardiac dysfunction.

Evaluation by cardiopulmonary exercise test of DDDR versus DDD pacing

In eight patients (age 62 +/- 6 years) a DDDR pacemaker was implanted for sick sinus syndrome (three cases) or second- and third-degree AV block (five cases). In five subjects chronotropic incompetence (maximal heart rate on effort < 110 beats/min) was present before implantation. One month after implantation the patients were randomized to DDDR or DDD pacing for 3 weeks each, with subsequent crossover, and at the end of each period a symptom limited cardiopulmonary exercise test (25 watts/2 min) was performed and the patients were requested to fill a symptoms questionnaire.

RESULTS

DDDR pacing, compared to DDD, was associated with higher maximal heart rates (127 +/- 20 vs 110 +/- 27 beats/min, P < 0.02), higher [VO2 max (25.4 +/- 6.1 vs 21.5 +/- 7.8 mL/kg/per min, P < 0.03) and higher VO2 at the anaerobic threshold (20.3 +/- 5.0 vs 15.8 +/- 4.9 mL/kg per min, P < 0.03), without significant differences in mean exercise time (526 +/- 193 vs 472 +/- 216 sec, NS). The increase in VO2 max obtained in DDDR versus DDD was significantly related to the increase in maximal heart rate (r = 0.72, P < 0.05) and the increase in VO2 at the anaerobic threshold obtained in DDDR versus DDD was related to the increase in heart rate at the anaerobic threshold (r = 0.81, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Food in chronic heart failure: improvement in central haemodynamics but deleterious effects on exercise tolerance

Food has been known to have significant central haemodynamic effects for over half a century; it causes an increase in cardiac output and a fall in systemic vascular resistance. These changes are potentially desirable in patients with chronic heart failure but how they relate to exercise tolerance is unknown. This study was designed to examine the haemodynamic effects of food with changes in exercise capability in a group of patients with chronic heart failure. Fifteen patients with chronic heart failure and 10 normal control subjects were studied. They underwent treadmill exercise testing whilst fasting and after a standardized meal. Measurements were made of symptom-limited exercise tolerance, cardiac output, limb blood flow and respiratory gases. Superior mesenteric artery blood flow was measured fasting and postprandially only. Despite an increase in cardiac output, at rest and during exercise, which was not, however, as great as that in the control subjects, the symptom-limited exercise tolerance of the patients fell by 37 s postprandially (P < 0.05). Superior mesenteric artery blood flow increased postprandially by a mean of 133 ml.min-1 (P < 0.05) in the patients and 424 ml.min-1 (P < 0.01) in the control subjects. Calf blood flow increased in both groups during exercise, but there was no change in limb blood flow when comparisons were made between the fasting and postprandial states. The normal postprandial increase in oxygen consumption did not occur in the patients although their minute ventilation was higher than the control subjects (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic importance of predischarge exercise capacity for long-term mortality and non-fatal myocardial infarction in patients admitted for suspected acute myocardial infarction and treated with metoprolol

To evaluate the influence of acute beta-blockade on the ability of predischarge exercise test data to predict long-term prognosis in patients admitted for suspected acute myocardial infarction, patients randomized at hospital admission to intravenous metoprolol or placebo were studied. Among 190 patients discharged alive, total 4-year mortality was 20.5% (n = 39); (33 cardiac deaths, 6 non-cardiac deaths). Non-fatal infarction rate was 6.8% (n = 13). Multiple logistic regression analysis revealed that total mortality and non-fatal infarctions were independently predicted by (a) inability to perform predischarge stress testing (event-free survival for patients exercise tested 79.5% vs 56.9% for patients not eligible for testing; relative risk (RR) 1.40, 95% confidence interval (CI) 1.10-1.78; P = 0.01), and (b) low predischarge exercise capacity (RR 1.44, CI 1.08-1.93; P = 0.034). ST segment shift > or = 1 mm did not predict mortality or reinfarction. Administration of metoprolol in the acute phase did not influence the predictive value of these parametres. It is concluded that assessment of exercise capacity at early exercise testing yields independent information for later death and myocardial infarctions, and that beta-blockade with metoprolol does not influence the predictive value of early exercise testing.

Aerobic capacity in rate modulated pacing

Whether heart rate or AV synchrony is the most important factor for an increase in aerobic capacity was evaluated in a comparative study between sinus bradycardia, VVIR, DDD, and DDDR stimulation. Sixteen patients (mean age 67 years) with chronotropic incompetence and implanted DDDR pacemaker (Telectronics META 1250) were randomly studied by cardiopulmonary exercise testing. All patients were exercised to their anaerobic threshold (AT) with the following heart rates: DDD 84 +/- 3, VVIR 110 +/- 5, and DDDR 116 +/- 6 beats/min. Mean oxygen uptake (VO2, mL/kg per min) at AT was 7.4 +/- 0.3 in DDD and VVIR modes. A 12% increase was measured in DDDR mode (8.3 +/- 0.4). Compared to VVIR work capacity in the DDDR mode was improved by 17% (41 vs 48 W/min). In patients with isolated sinus node disease (n = 9) the increase of VO2 and work capacity at AT during DDDR mode was more pronounced (16% and 20%, respectively, compared to VVIR). In patients with intermittent second or third degree AV block (n = 7) the differences between the pacing modes were not significant. This might partly be due to a lesser degree of chronotropic incompetence in this subgroup. In conclusion only the conjunction of heart rate increase and preservation of AV synchrony provides a significant improvement in aerobic capacity during exercise.

Relationship of cardiac allograft size and pulmonary vascular resistance to long-term cardiopulmonary function

The purpose of this study was to evaluate the long-term cardiopulmonary function of heart transplant patients who received disproportionately sized allografts for varying levels of pulmonary vascular resistance. Resting hemodynamics and oxygen uptake during exercise were recorded at 1 year after transplantation in 52 patients. No differences in resting heart rate, cardiac output, stroke volume, peak oxygen uptake during exercise, and exercise duration were found in recipients of undersized hearts (donor:recipient weight ratio [D:R] < 0.75), sized-matched hearts (D:R = 0.75 to 1.25), and oversized (D:R > 1.25) hearts. In a further analysis according to preoperative pulmonary vascular resistance, resting cardiac output (5.8 +/- 1.3 L/min) was normal, and peak exercise oxygen uptake (22.7 +/- 8.0 ml/kg/min) was mildly decreased in recipients of size-matched allografts with a pulmonary vascular resistance of less than 3 Wood units (size-matched hearts, with mild or no pulmonary vascular resistance). Of patients with moderate pulmonary hypertension (pulmonary vascular resistance > or = 3 Wood units), resting cardiac output was normal (5.1 +/- 0.6 L/min) in recipients of oversized hearts and was reduced (4.7 +/- 1.0 L/min) in recipients of sized-matched hearts (p < 0.05 versus recipients of size-matched hearts with pulmonary vascular resistance less than 3 Wood units).(ABSTRACT TRUNCATED AT 250 WORDS)

Active skeletal muscle mass and cardiopulmonary reserve. Failure to attain peak aerobic capacity during maximal bicycle exercise in patients with severe congestive heart failure

BACKGROUND

In addition to depressed cardiac reserve, peripheral factors may contribute to limit maximal exercise capacity in patients with congestive heart failure (CHF). To investigate the role of reduced active skeletal muscle mass, peak oxygen uptake (VO2, milligrams per kilogram per minute) was determined during maximal symptom-limited exercise involving the lower limbs (LL) alone and the lower limbs and upper limbs (LL+UL) combined in patients with CHF and in normal subjects of similar age and sex.

METHODS AND RESULTS

LL bicycle exercise was performed upright with a ramp protocol and continuous expired gas analysis. When respiratory exchange ratio (RER) reached 1.0, UL exercise was initiated at constant load with the use of a cranking device positioned at shoulder level. LL exercise alone and combined LL+UL exercise were performed on separate days in randomized order by 24 patients with CHF and seven normal subjects. In patients with CHF, peak VO2 was greater during combined LL+UL exercise than during LL exercise alone, i.e., 15.8 +/- 0.8 versus 14.2 +/- 0.9 ml.kg-1.min-1 (p < 0.001), whereas in normal subjects, maximal VO2 was similar during the two tests, i.e., 26.7 versus 26.2 ml.kg-1.min-1 (NS). The increase in peak VO2 during combined LL+UL exercise relative to LL exercise alone was almost exclusively observed in patients with peak VO2 < 15 ml.kg-1.min-1 (mean increase, 21.7 +/- 4.1%). Peak VO2 during combined LL and UL exercise did not increase relative to LL exercise alone in patients with peak VO2 > 15 ml.kg-1.min-1 and in normal subjects of similar age and sex, i.e., 0.1 +/- 4.0% and 2.0 +/- 2.3% respectively.

CONCLUSIONS

In contrast to normal subjects and patients with moderate CHF, patients with severe CHF do not exhaust their cardiopulmonary reserve during symptom-limited maximal LL exercise on a bicycle.

[Relationship of Doppler indexes of left ventricular filling and exertion tolerance]

The aim of this study was to evaluate if Doppler indexes of left ventricular filling are related to exercise capacity. Since a correlation between left ventricular filling pattern and causal blood pressure has been recently reported along a wide range of pressure values, a group of subjects with blood pressure ranging from normal to severely elevated values was studied. Twenty-four subjects (11 normotensives, 13 mild to severe hypertensive patients) underwent an echo-Doppler study and a maximal multistage cycloergometric exercise test. Since the cycloergometric test was limited by fatigue or dyspnea in all subjects, exercise duration was used as an effort tolerance index. Echocardiographic indexes of systolic function resulted normal in all subjects. Significant relationships with exercise duration were found for several indexes of left ventricular filling (A peak: r = -.743, p < .0001; A/E ratio: r = -.606, p < .005; early filling fraction: r = .639, p < .001). Exercise time was also significantly related to casual blood pressure, both systolic and diastolic. The relationships between transmitral blood flow and exercise capacity seem to indicate that an impairment of ventricular relaxation (as indicated by the progressive increase of atrial contribution) is associated with a decreased exercise tolerance, possibly because a progressively lower activation of Frank-Starling mechanism. Diastolic function thus seems to be able to affect exercise tolerance even in subjects with normal systolic function and blood pressure ranging from normal to severely elevated values.

Oxygen may improve dyspnea and endurance in patients with chronic obstructive pulmonary disease and only mild hypoxemia

Oxygen (O2) has been reported to improve exercise tolerance in some patients with chronic obstructive pulmonary disease (COPD) despite only mild resting hypoxemia (PaO2 greater than 60 mm Hg). To confirm these prior studies and evaluate potential mechanisms of benefit, we measured dyspnea scores by numeric rating scale during cycle ergometry endurance testing and correlated the severity of dyspnea with right ventricular systolic pressure (RVSP) measured by Doppler echocardiography during a separate supine incremental exercise test. Both sets of exercise were performed according to a randomized double-blind crossover protocol in which patients breathed compressed air or 40% O2. We studied 12 patients with severe COPD (FEV1 0.89 +/- 0.09 L [mean +/- SEM], FEV1/FVC 37 +/- 2%, DLCO 9.8 +/- 1.5 ml/min/mm Hg[47% of predicted], PaO2 71 +/- 2.6 mm Hg). With endurance testing on compressed air, PaO2 did not change significantly in the group as whole (postexercise PaO2 63 +/- 5.1 mm Hg, p = NS), but did fall to less than 55 mm Hg in four patients from this group. Duration of exercise increased on 40% O2 from 10.3 +/- 1.6 to 14.2 +/- 1.5 min (p = 0.005), and the rise in dyspnea scores was delayed. Oxygen delayed the rise in RVSP with incremental exercise in all patients and lowered the mean RVSP at maximum exercise from 71 +/- 8 to 64 +/- 7 mm Hg (p less than 0.03). Improvement in duration of exercise correlated with decrease in dyspnea (r2 = 0.66, p = 0.001) but not with decreases in heart rate, minute ventilation, or RVSP.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of factors limiting maximal exercise performance in cystic fibrosis

1. Maximal exercise capacity in cystic fibrosis is influenced by both pulmonary and nutritional factors: lung disease by limiting maximal achievable ventilation, and malnutrition through a loss of muscle mass. The associated reduction in everyday activities may result in peripheral muscle deconditioning. 2. We studied 14 stable patients with cystic fibrosis (six males, eight females) and 14 healthy control subjects (seven males, seven females) in order to assess the influence of these factors on exercise performance. Subjects underwent anthropometry to estimate muscle mass, spirometry to assess ventilatory capacity, a 30 s sprint on an isokinetic cycle ergometer to assess maximal leg muscle performance, and progressive cycle ergometry to assess overall exercise capacity. 3. Compared with control subjects, the patients with cystic fibrosis were of similar age and height but weighed proportionately less [% ideal weight (mean +/- SD): 94.3 +/- 9.64 versus 109.5 +/- 11.82] and showed evidence of airflow limitation [forced expiratory volume in 1.0 s (FEV1.0) 72.5 +/- 24.78 versus 112.6 +/- 14.25% of predicted]. 4. The patients with cystic fibrosis did less absolute (5.1 +/- 1.89 versus 7.3 +/- 1.97 kJ) but similar relative maximal (11.5 +/- 3.41 versus 13.1 +/- 3.55 kJ/kg lean body mass) sprint work. During progressive exercise, the group with cystic fibrosis achieved lower absolute [maximal O2 consumption (VO2max.) 1.8 +/- 0.527 versus 3.0 +/- 0.655 litres/min] and relative (VO2max./kg lean body mass: 40.5 +/- 9.23 versus 53.0 +/- 11.62 ml min-1 kg-1) work levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise capacity and ventilatory, circulatory, and symptom limitation in patients with chronic airflow limitation

Dyspnea, leg effort (Borg 0 to 10 scale), ventilation, and heart rate (VEmax/VEcap; HRmax/HRcap expressed as a percentage of capacity) were measured at maximal exercise (cycle ergometer) in 97 patients with chronic airflow limitation (CAL) (FEV, 46.6 +/- 14.23% of predicted) and compared with 320 matched control subjects. Patients with CAL achieved a maximum power output of 86 +/- 39.5 W (60 +/- 23.2% of predicted) compared with 140 +/- 37.5 W (98 +/- 14.5% of predicted) in controls (p less than 0.0001), VEmax/VEcap was 72 +/- 19.3% compared with 53 +/- 18.6% (p less than 0.0001), and HRmax/HRcap was 76 +/- 13.5% compared with 82 +/- 13% (p less than 0.001). These findings were expected. The median intensity of dyspnea was 6 (severe to very severe) and leg effort was 7 (very severe) in both groups, and these findings were unexpected. The patients with CAL were handicapped by an increase in both dyspnea and peripheral muscular effort relative to the actual power output. The rating of dyspnea exceeded leg effort in 25 (26%) of CAL versus 69 (22%) control subjects: the rating of leg effort exceeded dyspnea in 42 (43%) CAL and 117 (36%) control subjects; both were rated equally in 30 (31%) CAL and 134 (42%) control subjects, respectively (NS). VEmax/VEcap and HRmax/HRcap were not significantly different in those limited by dyspnea, leg fatigue, or a combination of both. All values are expressed +/- SD.

Haemodilution in patients with peripheral arterial occlusive disease

Haemodilution is an efficient conservative therapy of peripheral arterial occlusive disease. Already a single isovolaemic haemodilution (replacement of 500 ml blood for Haes* 0.5, 10%) increases the pain-free walking distance by 85%. These effects can be maintained by a constant therapy over six weeks and following haemodilution once or twice per month. The haematocrit values should be between 38 and 42%. The haemodilution should be done hyper- or isovolaemically. Not more than 250 ml blood and 500 ml Haes should be infused during one session in order to avoid hypovolaemia. This means an infusion of 250 ml Haes, venesection of 250 ml blood via the same access and then infusion of the remaining 250 ml. The whole procedure should not last more than one hour. Blood pressure, heart rate, lung auscultation and percussion as well as creatinine values has to be controlled during an intensive therapy. If the hydroxyethyl starch concentration exceeds 150 g per week pruritus may occur in singular cases, if the concentration exceeds 700 g per week it is observed in 50% of the cases. Provided the preventive measures are observed haemodilution is an efficient and good therapy which also increases the compliance to practice vascular exercise.

The influence of different space-related physiological variations on exercise capacity determined by oxygen uptake kinetics

Oxygen uptake kinetics, following defined variations of work load changes allow to estimate the contribution of aerob and anaerob energy supply which is the base for determining work capacity. Under the aspect of long duration missions with application of adequate dosed countermeasures, a reliable estimate of the astronaut's work capacity is important to adjust the necessary inflight training. Since the kinetics of oxygen uptake originate in the working muscle group itself, while measurements are performed at the mouth, various influences within the oxygen transport system might disturb the determinations. There are not only detraining effects but also well-known other influences, such as blood- and fluid shifts induced by weightlessness. They might have an impact on the circulatory system. Some of these factors have been simulated by immersion, blood donation, and changing of the body position.

[Enalapril improves hemodynamics and exercise tolerance in pulmonary heart disease caused by obstructive lung disease]

Chronic enalapril therapy was assessed in 11 patients with cor pulmonale due to chronic obstructive pulmonary disease. Enalapril was added to the maintenance dose of diuretics and digitalis and when clinical stabilisation was achieved haemodynamics, spirometry, blood gases and maximal treadmill exercise test accompanied by +pulse oximetry were performed before and after 30 days, 10-20 mg a day, enalapril therapy. Haemodynamic study showed moderate but significant decrease in mean pulmonary artery pressure, from 24 +/- 3 to 21 +/- 5 mmHg (p = 0.05). There were no substantial differences in cardiac output as well as in blood gases and spirometry after enalapril therapy. Slight decrease in oxygen delivery, on an average from 9157 +/- 3808 to 8074 +/- 3574 (p = NS), was accompanied by a concomitant fall in haemoglobin. We noted significant improvement of maximal exercise test results after enalapril therapy. Maximal workload achieved and the time of exercise increased. It was accompanied by subjective improvement as assessed by Borg scale. We observed no adverse effects of enalapril during one month therapy in patients with cor pulmonale and COPD.

[Evaluation of physical fitness of children with mitral valve prolapse into the left heart atrium]

Effort tolerance was assessed in 25 children with idiopathic syndrome of mitral valve leaflet prolapse into the left atrium. The children were aged 9 to 15 years. The results of the ergometric test confirmed the clinical observations suggesting that children with the syndrome tolerate exercise as well as their healthy peers.

[Evaluation of clinical effectiveness and adverse effects of Polnitrin]

In a double-blind, randomized, placebo cross-controlled trial the effectiveness and the adverse effects of two types of buccal tablets containing 5 mg nitroglycerin: Polnitrin produced by Warsaw Pharmaceutical Works POLFA and its analogue of foreign origin, were assessed. The third compared preparation was sublingual nitroglycerin in 0.5 mg tablets. The longest dissolution in the buccal cavity showed Polnitrin (mean 6.6 hours). Polnitrin significantly increased the resting heart rate during 3 hours, and during 6 hours at maximal effort. The foreign analogue decreased significantly the systolic pressure during 3 hours after application. No significant differences were noted in the effects on the basic haemodynamic parameters between the compared buccal tablets. Exercise tolerance and coronary reserve were assessed with repeated exercise tests on moving track (Marquette Case-12). Immediately after being stuck to the gum Polnitrin, its analogue and sublingual nitroglycerin significantly prolonged the marching time: total, till pain, and till ischaemia. After 6 hours the marching time till pain appearance was significantly longer after Polnitrin than after placebo or its analogue. Local adverse effects connected with the presence of the tablet in the oral vestibule may hamper the treatment with Polnitrin in some cases. The most frequent side effect were headaches which are known to occur usually after all nitrates.

[Comparative evaluation of cardiovascular function in patients after myocardial infarction during exercise test with the optimal and sub-optimal frequency of pedalling]

Cardiovascular function was studied in 59 patients with myocardial infarction during their bicycle ergometer exercise performance at optimal and +sub-optimal pedalling rates. The total performance at the optimal rate was found to average 1.48 times more than that at the +sub-optimal rate. The efficiency of cardiovascular performance was achieved by a less increase in heart rate and systolic pressure. ECG changes resulting in exercise test cessation were observed in 7 and 30 cases at the optimal and +sub-optimal rates, respectively. It is concluded that physical training that fails to impose patients' rhythm and exercise capacity are more physiological and maximally safe.