Rate control of physiologic pacemakers by central venous blood temperature

Heart rate and central venous blood temperature (CVT) were measured in 31 people with different exercise capacities by means of a thermistor integrated into a lead that was placed in the right ventricle. Bicycle ergometric and treadmill stress tests with increasing workloads were performed. The maximum increase in CVT with ergometric exercise was found to be 1.3 degrees C at 250 W in healthy young volunteers and 1.0 degrees C at 125 W in cardiac patients. Despite a relatively greater increase in CVT in the elderly patients compared with the volunteers, the correlation between the increase in CVT and that in heart rate at the end of each exercise stage was found to be very high (r = .9693 in volunteers and r = .9864 in cardiac patients), independent of physical fitness. Even with everyday activities such as walking there was a marked increase in CVT. Due to its close relationship to human metabolism, CVT represents a good parameter for physiologic control of pacing rate.     

Effect of respiration on variations of central venous blood temperature

We examined the course of right ventricular blood temperature before, during and after treadmill exercise in three patients with implanted cardiac pacemakers, and in two healthy volunteers. Temperature measurements were performed with a specially developed 5F electrode with an incorporated thermistor (measurement accuracy: 1/100 degrees C). After electronic amplification, the temperature signals were recorded on a three-channel strip chart recorder, together with ECG and respiration (measured by impedance plethysmography). In one of the volunteers, blood flow in the jugular and femoral veins was recorded by Doppler sonography, before and after exercise. We observed a decrease in central venous blood temperature with inspiration and an increase with expiration before, during and after exercise. The amplitudes of the variations became smaller during exercise, reached a maximum immediately after exercise and returned to their resting values within a few minutes after the end of exercise. We suppose different distributions of venous blood flow in different phases of the respiratory cycle to be the reason for the respiration-induced variations in central venous blood temperature. Under exercise conditions, the influence of respiration on the blood flow in the larger veins is small compared to the influence of an increased cardiac output; at rest, respiration has a more pronounced effect on venous blood flow. The analysis of our blood flow measurements in the femoral and jugular veins supported this assumption.     

Case studies on the effect of exercise and hot water submersion on intracardiac temperature and the performance of a pacemaker which varies pacing rate based on temperature

The effectiveness of using blood temperature change as an indicator to automatically vary heart rate physiologically was evaluated in 3 patients implanted with Model Sensor Kelvin 500 (Cook Pacemaker Corporation, Leechburg, PA, USA) pacemakers. Each patient performed two block-randomized treadmill exercise tests: one while programmed for temperature-based, rate-modulated pacing and the other while programmed without rate modulation. In 1 pacemaker patient and 4 volunteers, heart rates were recorded during exposure to a hot water bath. Blood temperature measured at 10 sec intervals and pacing rate measured at 1 min intervals were telemetered to a diagnostic programmer and data collector for storage and transfer to a computer. Observation comments and ECG-derived heart rates were manually recorded. The temperature-based pacemaker was shown to respond promptly not only to physical exertion but also to emotionally caused stress and submersion in a hot bath. These events cause increased heart rate in the normal heart. Using a suitable algorithm to process the measurement of blood temperature, it was possible to produce appropriate pacing rates in paced patients.     

Temperature-controlled Rate Responsive Pacing with the Aid of an Optimized Algorithm

On the basis of earlier studies of the behavior of the central venous blood temperature at rest and during exercise, we have developed an algorithm for the rate control of cardiac pacemakers. The central venous blood temperature serves as the control variable for the pacing rate. Control is effected via two different characteristic lines that relate pacing rate and temperature. A rest characteristic line relates absolute temperature values to heart rate and exercise lines relate relative changes in temperature to heart rate changes. The rest characteristic corresponds to conditions of slow temperature fluctations (e.g., fever and temperature changes due to circardian rhythm) and has a slope of 15 to 20 bpm per centigrade degree of temperature change. Starting at this rest characteristic, there are exercise characteristic lines that have a much greater slope and serve to regulate the pacing rate under exercise conditions. The two characteristics are distinguished via the temperature change per unit of time. In addition, a return characteristic connects the rest and exercise characteristics. This algorithm allows for optimized rate adaption of physiological cardiac pacemakers by central venous blood temperature. Clinical studies with the implanted device (Intermedics Nova MR) prove the correct function and beneficial effect of this algorithm in patients' everyday life.     

Rate-responsive pacing with a pacemaker that detects respiratory rate (Biorate): clinical advantages and complications

The respiratory-dependent pacemaker (RDP3 or MB-1, Biorate, Biotec International, S.p.A., Bologna, Italy) detects the respiratory rate by measuring thoracic impedance using a subcutaneous auxiliary lead. The sensed respiratory rate is used to determine the pacing rate response. This pacemaker had been implanted in 9 patients with a mean age of 58 (range 42-69) years. During symptom-limited treadmill exercise, rate-modulated pacing resulted in a significant increase in pacing rate (mean +/- SD, 124 +/- 10 vs. 71 +/- 3 beats/min p less than 0.001) and exercise capacity (343 +/- 147 vs. 463 +/- 120 s, p less than 0.05) compared to those achieved with constant rate ventricular pacing. Brief treadmill exercise tests showed appropriate rate response to increased walking speed and gradient. However, rate response was modified by arm swinging-induced motion artefact which affected the measured "impedance." Complications observed on follow-up included perforation of the auxiliary lead in 2 patients and symptomatic myopotential interference in 3 patients with the RDP3 pacemaker, all of whom required unit replacement. It is concluded that although the respiratory-dependent pacemaker can confer physiological benefit in patients with bradycardia, myopotential interference (largely overcome by the new version MB-1 with programmable sensitivity) and the auxiliary lead can be problematic in some patients.     

Adaptive Rate Pacing at Submaximal Exercise: The Importance of the Programmed Upper Rate

The contributions of rate response and different programmed upper rates to sub-maximal exercise were studied in 12 patients with implanted adaptive rate pacemakers (9 Meta, 3 Activitrax). Their median age was 69 years (range 33–80). All were paced from the right ventricle except for one patient with sinoatrial disease who received an atrial Meta pacemaker. In the constant rate pacing (SSI) mode, the reproducibility of a Submaximal stress test (maximum distance covered within a 12-minute walking test) was investigated by repeating the test three times. An initial training effect was obserbed between the first and the second test, but no further increase in walking distance occurred between the second and third test and the distances covered were highly reproducible (r = 0.99). The rate adaptive function was activated with the upper rate randomly programmed to 100, 125, 150, and 165 beats/min. Compared with exercise in the SSI mode, rate adaptive pacing with the upper rate programmed to 125 and 150 beats/min resulted in enhancement of exercise distance (4.7%± 1.2% and 4.4%± 1.2%, respectively, P < 0.005). Upper rates of 100 and 165 beats/min did not improve submaximal exercise performance, and at an upper rate of 165 beats/min, three patients developed complications (angina, dyspnea, and atrial fibrillation). It is concluded that the 12-minute walking test is a reproducible method to assess exercise capacity in pacemaker patients. Adaptive rate pacing improved exercise performance during daily activities, although the extent of the benefit appeared to be small and dependent on the programmed upper rate. An exercise test such as a 12-minute walking test should be performed before a high upper rate is programmed.     

Evaluation of six minute walking test in patients with single chamber rate responsive pacemakers.

OBJECTIVE--To validate a simplified exercise protocol (the six minute walk) as a means of evaluating pacing modes and rate responsive pacemakers. DESIGN--Two groups of patients with different pacemaker types (activity and dual sensor) were randomly assigned to four consecutive pacing settings (fixed rate--or VVI at 60, 85, and 110/min, and optimal rate response--or VVIR). A third group of elderly patients without arrhythmias or conduction disturbances formed a control population. SETTING--Ambulatory consultation for patients with a pacemaker in a tertiary referral centre for treatment of arrhythmias. SUBJECTS--16 patients with rate responsive pacemakers for complete heart block and limited functional capacity and 13 controls with normal chronotropic competence. INTERVENTIONS--Submaximal exercise protocol with 6 minutes walking and continuous recording of electrocardiogram. MAIN OUTCOME MEASURES--Achieved distance and scored degree of exertion during walking in the four settings in the patients with a pacemaker; differences in rate behaviour in VVIR mode between the two pacemaker types; comparison of the pacing rate with the heart rate of the control population. RESULTS--The six minute walk was performed better in VVIR than VVI 60. In VVI 85 the distance was also significantly longer than in VVI 60. The rise in pacing rate of activity pacemakers was steeper than that of the dual sensor pacemakers and differed from the heart rate in the controls at 90 seconds. CONCLUSIONS--The studied test protocol was able to show differences in exercise capacity between pacing modes. Different rate responses between the evaluated sensor types could be established. The six minute walking test gives enough information to program and reprogram single chamber rate responsive pacemakers.     

Core and peripheral temperature response to exercise in patients with impaired left ventricular function.

OBJECTIVE--Exercise induced hypotension is a specific but insensitive indicator of severe coronary artery disease. Skin blood flow is subject to control by baroreceptor mediated reflexes as well as thermoregulatory reflexes. Monitoring skin temperature or the skin to central temperature gradient may be a more sensitive indicator of impaired cardiac output response to exercise than hypotension. DESIGN AND PARTICIPANTS--Central and skin temperature changes associated with exercise were studied in 10 normal volunteers and eight patients with impaired resting ventricular function due to ischaemic heart disease. Patients exercised according to a modified Bruce protocol. The two sample independent t test was applied to compare the central and peripheral temperatures in the two groups at three minute intervals during exercise and at two minute intervals after exercise. RESULTS--A significant decrease was found in mean (1 SEM) central temperature on exercise in our patient group (98.2(0.2) degrees F to 97.2(0.3) degrees F), compared with the normal increase in central temperature (97.7(0.2) degrees F to 98.3(0.3) degrees F). Mean (1 SEM) skin temperature changes reflected the expected skin blood flow changes with exercise in normal subjects. In the patient group skin temperature declined during exercise (89.7(2.1) degrees F to 86.6(1.7) degrees F) and was significantly lower than normal from six minutes onwards. CONCLUSIONS--The abnormal peripheral temperature changes of patients with impaired resting ventricular function is an early and sensitive indicator of an abnormal haemodynamic response to exercise. It is possible that skin temperature measurement during exercise could help detect exercise induced ventricular dysfunction due to ischaemia or impaired cardiac output due to valvar heart disease.     

Tricuspid valve malfunction and ventricular pacemaker lead: case report and review of the literature

Pacemaker implantation can be associated with several complications, including myocardial perforation with or without pericardial effusion, venous thrombosis, vegetations of the tricuspid valve (TV) or pacing lead, and tricuspid regurgitation (TR). The TR is thought to be derived from deformity or perforation of the TV by the pacing lead or secondary to atrioventricular discordance with asynchronous ventricular pacing. Severe TR can be deleterious to the patient because it raises the central venous pressure by increasing the right sided preload. Chronically, the increase in right sided blood volume can result in an increase in the right atrial pressure leading to a decrease in venous return and low cardiac output. Severe TR from leaflet adhesion to the pacemaker lead has not been reported before. With the aging of the population and the expanding use of pacemakers and implantable cardioverter defibrillators (ICD) in clinical practice, this complication may be seen more frequently. We present a patient diagnosed with severe TR, years after his pacemaker implantation. His TR was thought to be caused by adhesion of the tricuspid valve to his pacemaker lead.     

Ventricular pacing improves exercise tolerance in patients with chronic heart block.

Exercise capacity was assessed by means of a simple six minute walking test in a group of 18 patients with heart block whose only presenting symptom was breathlessness. None was in overt cardiac failure. Patients were studied before and after implantation of a transvenous, ventricular, demand pacing system (study group). Eight patients with an implanted pacemaker admitted for elective generator replacement were assessed in the same manner (control group). Exercise capacity in the study group was significantly increased within 48 hours of pacing, and this improvement was maintained in most patients during the follow up period of up to 30 months. In contrast, exercise capacity was unaffected by generator replacement in the control group. Simple ventricular pacing produces symptomatic benefit in patients with heart block accompanied by breathlessness. This benefit is apparent within 48 hours of pacing and is maintained; it can be assessed objectively by a six minute walking test.     

Cardiopulmonary stress: control of the function of frequency variable pacemaker systems

Based on the linear relationship between cardiac output and oxygen uptake direct breath-to-breath gas exchange measurements during exercise allow accurate determinations of cardiopulmonary function. We used cardiopulmonary exercise testing to assess the physiologic benefit of rate response VVIR pacing in 17 patients with chronotropic incompetence. 13 patients had an activity-rate-response pacemaker, two patients had a temperature-controlled pacemaker and two patients a respiratory-dependent system. Exercise testing was performed with the pacemaker, either programmed to fixed rate VVI or to rate variable VVIR pacing. All patients were exercised on a bicycle using a ramp protocol with 10 to 20 watts/min increments. Maximal oxygen uptake and the anaerobic threshold were determined. Compared with findings in the VVI mode, rate response VVIR pacing increased maximal exercise heart rate from 74 +/- 10 to 118 +/- 21 bpm (p less than 0.001). This increase in heart rate was associated with an increase of maximal oxygen uptake from 14.3 +/- 5 to 18.3 +/- 6 ml/kg per min (p less than 0.04) and a delay of the anaerobic threshold to a higher oxygen consumption of 14.6 +/- 5 vs 10.6 +/- 5 ml/kg per min (p less than 0.04). The individual increase in oxygen uptake was a direct function of the change in exercise heart rate independent of the implanted pacing device. The improved aerobic capacity resulted in a 17% increase in exercise tolerance and a 19% increase of exercise time. Cardiopulmonary exercise testing appears to be a useful noninvasive technique to quantify the cardiopulmonary benefit of rate response pacing.     

Ventricular pacing improves exercise tolerance in patients with chronic heart block

Exercise capacity was assessed by means of a simple six minute walking test in a group of 18 patients with heart block whose only presenting symptom was breathlessness. None was in overt cardiac failure. Patients were studied before and after implantation of a transvenous, ventricular, demand pacing system (study group). Eight patients with an implanted pacemaker admitted for elective generator replacement were assessed in the same manner (control group). Exercise capacity in the study group was significantly increased within 48 hours of pacing, and this improvement was maintained in most patients during the follow up period of up to 30 months. In contrast, exercise capacity was unaffected by generator replacement in the control group. Simple ventricular pacing produces symptomatic benefit in patients with heart block accompanied by breathlessness. This benefit is apparent within 48 hours of pacing and is maintained; it can be assessed objectively by a six minute walking test.     

Effect of AV synchronization and rate increase on hemodynamics and on atrial natriuretic peptide in patients with total AV block

We studied nine patients (56 +/- 7 years) with complete AV-block and permanent dual-chamber pacemaker (DDD) under different pacing modes: ventricle pacing (VVI) 70 bpm, DDD 106 +/- 4 bpm, rate adaptive pacing (VVI-FA) 108 +/- 3 bpm. Exercise was performed supine on the bicycle ergometer at 50 watts for 5 min at each setting. DDD-paced patients showed significantly higher mixed venous oxygen saturation, being 45 +/- 2% after the fourth minute, (VVI 38 +/- 2%, p less than 0.01 and VVI-FA paced patients 40 +/- 1%, p less than 0.01). Pressures were normal under DDD pacing during exercise (RAP 7 +/- 2 mm Hg; PCP 14 +/- 3 mm Hg) and showed further increase to abnormal levels during VVI (RAP 13 +/- 2 mm Hg, p less than 0.01; PCP 21 +/- 3 mm Hg, p less than 0.02) and VVI-FA pacing (RAP 10 +/- 2 mm Hg, p less than 0.05; PCP 20 +/- 3 mm Hg, p less than 0.01). Stroke volume increased from 71 +/- 5 ml to 105 +/- 7 ml during VVI and from 64 +/- 7 ml to 81 +/- 7 ml during DDD pacing. Stroke volume remained unchanged (69 +/- 5 ml) during VVI-FA pacing. The peak levels of ANP during and after exercise were significantly higher under VVI (951 +/- 248 pg/ml) than under DDD pacing (650 +/- 140 pg/ml, p less than 0.01) and were not different between DDD and VVI-FA pacing (677 +/- 97 pg/ml). These results show that VVI pacing effects a more pronounced increase of ANP level than other pacing modes. Under moderate exercise, rate-responsive pacing compared to VVI pacing showed no differences in mixed venous oxygen saturation and in atrial pressures. Only DDD pacing showed higher oxygen saturation and a normalization of atrial pressures when compared to other types of single chamber pacing.     

Cardiopulmonary exercise test in patients with DDD pacemaker: report of two cases with increased exercise capacity by decreased ventricular tracking limit rate setting]

We reported 2 patients with complete A-V block with a DDD pacemaker whose exercise capacity was increased by decreased ventricular tracking limit rate setting (VTL) of their pacemakers. Cardiopulmonary exercise test was used for estimating exercise capacity. Case 1: A 15-year-old girl complained of fainting. Her electrocardiogram (ECG) revealed complete A-V block (atrial rates 100/min, ventricular rates 39/min). After implantation of a DDD pacemaker and the VTL setting at 152/min, her bradycardia disappeared, however, she complained of dyspnea after a few minutes' walk. We performed symptom-limited cardiopulmonary exercise test with a motor-driven treadmill. When the pacing rate reached VTL (152/min), ECG suddenly changed to approximately 2:1 pacing (80/min) and the patient complained of dyspnea. Concomitant rapid increases in VE, VCO2 and RQ suggested that dyspnea was caused by the marked change in pacing rates on VTL. With the lowered VTL (110/min), there was no rapid increase in VE, VCO2 and RQ, and dyspnea subsided when the pacing rate reached VTL. At the same time, the peak VO2 and exercise time were increased by 15% and 8%, respectively. Case 2: A 47-year-old man complained of syncope. His ECG revealed complete A-V block (atrial rates 100/min, ventricular rates 33/min). After a DDD pacemaker implantation (VTL: 150/min), he experienced dyspnea while walking up the stairs in his office. Like in Case 1, when the VTL was lowered from 150/min to 110/min, both the peak VO2 and exercise time were increased by 11%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of left ventricular function and Doppler-derived variables in predicting hemodynamic benefits of rate-responsive pacing

Cardiac hemodynamics were studied in 22 patients (mean age 55 +/- 2 years, range 22 to 73) with rate-responsive pacemakers using the continuous-wave Doppler method to assess ascending aortic blood flow. Compared with constant rate ventricular (VVI) pacing, rate-responsive pacing conferred improvements in exercise capacity (39 +/- 9%, p less than 0.001) and cardiac output (41 +/- 8%, p less than 0.001). Cardiac output increased by 141 +/- 21% over the resting value and 56% of this increase was mediated by the ability of these pacemakers to increase their pacing rate. Doppler-derived peak aortic flow velocity, acceleration and stroke distance were lower during maximal exercise in the rate-responsive mode and there was a trend toward a higher systolic blood pressure response. Neither age nor echocardiographic and Doppler-derived variables (at rest and during peak exercise in the VVI mode) could predict the hemodynamic and functional benefits conferred by rate-responsive pacing during exercise, although left ventricular function had a weak correlation. It was concluded that rate-responsive pacing significantly benefits patients with bradycardia, although the extent of the benefit is not predictable, and that advanced age alone should not be a barrier to the use of a rate-responsive pacemaker.     

Clinical and hemodynamic comparison of VVI versus DDD pacing in patients with DDD pacemakers

To identify better those subgroups of pacemaker recipients who will benefit from dual chamber pacing, 19 patients with DDD pacemakers that were physiologically paced were entered into a blinded, randomized protocol comparing long-term VVI versus DDD pacing. Patients were evaluated in each of the pacing modes for exercise performance, cardiac chamber size, cardiac output, functional status and health perception. Eight patients (42%) insisted on early crossover, from VVI to DDD pacing, after only 1.8 +/- 1.4 weeks because of symptoms consistent with pacemaker syndrome. Overall, 12 patients preferred DDD pacing and no patient preferred VVI pacing (p = 0.001). Percent fractional shortening (30 +/- 8 vs 24 +/- 6%, p = 0.009) and cardiac output (6.3 +/- 2.6 vs 4.4 +/- 2.2 liters/min, p = 0.0001) where significantly greater in the DDD mode. Exercise duration was greater during DDD compared with VVI pacing (11.3 +/- 3.7 vs 10.1 +/- 3.7 minutes, p = 0.006). However, it was only in the crossover subgroup that DDD pacing resulted in significant improvement in exercise performance and health perception compared with VVI pacing. This subgroup of patients was characterized by an intrinsic sinus rate of less than 60 beats/min (4/8 vs 0/11, p = 0.006), ventriculoatrial (VA) conduction (4/8 vs 1/11, p = 0.048), greater increase in exercise peak systolic blood pressure from VVI to DDD mode (21 +/- 12 vs 4 +/- 13 mm Hg, p = 0.02) and greater improvement in exercise capacity from VVI to DDD pacing (2.2 +/- 1.2 vs 0.6 +/- 1.4 minutes, p = 0.03) compared with the other 11 patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Short-term immobilization of healthy men: right ventricular function and metabolism during graded exercise.

Five healthy male volunteers were subjected to graded exercise tests on a bicycle ergometer (600 kpm/min for 8 minutes) with simultaneous catheterization of the right cardiac ventricle and radial artery, first before immobilization and them after five-day bed rest in the head-down posture (the foot bed end was elevated 4.5 degrees). After immobilization, during exercise the stroke index did not increase, the tachycardia was more marked, the indicators of right ventricular contractility increased [+ max dp/dt, mas (dp/dt) /P, --mas dp/dt], the arterial pressure decreased, and the lactic acid level in mixed venous blood rose. Possible causes of haemodynamic and metabolic alterations, occurring in healthy volunteers during graded exercise following short-term hypokinesis, are discussed.     

Comparison of dual chamber and ventricular rate responsive pacing in patients over 75 with complete heart block.

OBJECTIVE--To compare symptoms and exercise tolerance during dual chamber universal (DDD) and ventricular rate response (VVIR) pacing in elderly (> or = 75) patients. DESIGN--Randomised, double blind, crossover study. SETTING--Regional cardiac department. PATIENTS--Twenty elderly patients (mean age 80.5 (1) years) with high grade atrioventricular block and sinus rhythm. Patients with pre-existing risk factors for the pacemaker syndrome and chronotropic incompetence were excluded. INTERVENTION--After four weeks of VVI pacing following pacemaker implantation, patients underwent consecutive two week periods of VVIR and DDD pacing. MAIN OUTCOME MEASURES--Patient preference, symptom scores, "daily activity exercises," and perceived level of exercise (Borg score). RESULTS--Eleven patients preferred DDD mode to either VVI or VVIR mode. Mean (SE) total symptom scores during VVI, VVIR, and DDD pacing were 5.9 (1.1), 6.1 (1.0), and 3.5 (0.9) respectively (P < 0.01). The corresponding mean (SE) pacemaker syndrome symptom scores were 4.8 (0.7), 5.2 (0.8), and 2.9 (0.8) (P < 0.05). Symptom scores during VVI and VVIR pacing were not significantly different. Exercise performance and Borg scores were significantly worse during VVI pacing compared with VVIR or DDD pacing but did not significantly differ between VVIR and DDD modes. CONCLUSIONS--In active elderly patients with complete heart block both DDD and VVIR pacing are associated with improved exercise performance compared with fixed rate VVI pacing. The convenience and reduced cost of VVIR systems, however, may be offset by a higher incidence of the pacemaker syndrome. In elderly patients with complete heart block VVIR pacing results in suboptimal symptomatic benefit and should not be used instead of DDD pacing.     

Comparison of oxygen consumption in performing daily activities between patients with chronic obstructive pulmonary disease and a healthy population

OBJECTIVE: The purposes of this study were to compare the daily activity oxygen consumption (VO(2)) and peak oxygen consumption (VO(2peak)) for chronic obstructive pulmonary disease (COPD) patients and healthy individuals; to compare dyspnea levels found in COPD patients and healthy individuals when they performed daily activities and exercise tests; and to establish standard VO(2) values for daily activities for COPD patients. DESIGN: This was an exploratory and correlative study. SETTING: The study took place at the Research Center of Sports Medicine at Taipei Medical University, in Taipei, Taiwan. SUBJECTS: The study included 27 COPD patients and 18 healthy subjects whose ages, weights, and heights were matched. Outcome Measures: VO(2peak) and the VO(2) for performing daily activities including sitting, standing, walking, walking with a 2-kg load, and walking upstairs for 2 stories. INTERVENTION: All data were collected by means of questionnaires and treadmill exercise tests. VO(2) was measured using an AEROSPORT KB1-C metabolic measurement system. RESULTS: There was no significant difference in VO(2) found between the 2 groups when they were performing daily activities, but the VO(2peak) was significantly lower in the COPD group (13.90 +/- 2.93 mL kg(-1) min(-1)) compared with the healthy control group (16.15 +/- 1.86 mL kg(-1) min(-1)) (P =.01). The dyspnea level of the COPD group when they were performing daily activities and exercise tests was more severe than that of the healthy control group. The mean VO(2) values for daily activities in COPD patients were as follows: sitting 3.41 (+/-0.82), standing 3.67 (+/-0.90), walking 10.06 (+/-2.19), walking with a 2-kg load 10.28, and walking upstairs 8.16 (+/-1.36) mL kg(-1) min(-1). CONCLUSION: The results of this study reveal that there were no differences in VO(2) values for performing daily activities between COPD patients and healthy individuals. However, an increase in dyspnea level occurred during daily activities, and it was found to be more severe for COPD patients than for healthy individuals. A key factor was probably that COPD patients had an obviously lower VO(2peak) and higher relative exercise intensity for daily activities than did healthy individuals.     

Palm temperature monitoring during exercise in patients with heart disease

The quantitative use of palm temperature changes during a fixed-load treadmill exercise was evaluated in normal subjects and patients with various degrees of cardiac disability. Treadmill exercise revealed different temperature patterns between subject groups. Normal subjects showed an initial transient decrease to a plateau phase, followed by a prompt return to the control level after cessation of exercise. Cardiac patients with severe disabilities showed a progressive decrease during and even after exercise, and the return to the control level was delayed. Patients with less severe cardiac disabilities showed an intermediate pattern. A significant correlation was observed between the temperature pattern and the plasma catecholamine concentration. The simultaneous measurement of forearm and hand blood flow, and palm temperature during a supine ergometer exercise showed that the temperature change reflected the blood flow changes. In conclusion, palm temperature monitoring during treadmill exercise is a simple and useful method for assessment of the vasoconstrictor response to exercise and, therefore, the pattern of temperature changes indicates indirectly the exercise capacity in heart disease.