Automated blood pressure measurements during exercise

A new and specific automated blood pressure device for exercise stress testing

Blood pressure (BP) measurement plays a critical role in cardiac stress testing and is most commonly assessed manually. The emphasis of social distancing during the COVID-19 pandemic has renewed the interest in and the need for an automated BP device for incremental exercise stress testing. We assessed the accuracy of a new automated blood pressure device specifically manufactured for cardiac stress testing. Thirty-five adults aged 35 ± 16 years were studied during an incremental stress test on the cycle ergometer. Three observers measured BP simultaneously, two listening to Korotkoff sounds using a dual-headed stethoscope and one using headphones to listen to sounds generated by an automated BP device. With increasing workload, systolic BP increased progressively without significant differences in BP readings between any observer compared with the automated monitor at any stage during exercise. Systolic BP obtained with the BP machine was strongly correlated with those obtained by the stethoscope observers (r = 0.96) and the observer with headphones (r = 0.95). Diastolic BP obtained with the BP machine was moderately and significantly associated with those obtained by the stethoscope observers (r = 0.75) and the observer with headphones (r = 0.75). The automated BP monitor specifically made for cardiac stress testing accurately measured both systolic and diastolic blood pressure during exercise.

Increased mean arterial pressure response to dynamic exercise in normotensive subjects with multiple metabolic risk factors

Metabolic syndrome (MS) may influence vascular reactivity and might cause an excessive increase in blood pressure (BP) during dynamic exercise. We examined this hypothesis in 698 normotensive men (mean age: 43 years) free of cardiovascular disease, diabetes mellitus and renal disease. The response of BP to exercise was assessed by the mean arterial pressure (MAP) during bicycle ergometry. The MAP values were expressed as z-scores normalized to the relative increases in heart rate. High-normal BP, dyslipidemia and hyperglycemia were diagnosed according to the Japan-specific MS criteria. The z-score of MAP was significantly higher in subjects with high-normal BP (+0.57, P<0.001), dyslipidemia (+0.18, P<0.001) and hyperglycemia (+0.24, P<0.001) than in those without MS component (-0.38). In the high-normal BP subjects, the addition of dyslipidemia and/or hyperglycemia was associated with a progressive increase in the z-score of exercise MAP, whereas no such association was observed in the normal-BP subjects (P=0.033, two-way ANOVA). Multivariate regression analysis revealed that a greater number of MS components (β=0.102, P=0.010) was an independent determinant of increased MAP z-score after adjustment for potential confounders, including age (β=0.123, P<0.001), body mass index (β=0.145, P<0.001) and high-normal BP (β=0.410, P<0.001). These results suggest that accumulation of MS components may alter vascular structure and function and lead to the significant elevation of MAP during dynamic exercise even before clinical manifestation of arterial hypertension.

Cerebral oxygenation during exercise and exercise recovery in patients with idiopathic dilated cardiomyopathy

We compared cerebral oxygenation during exercise and during exercise recovery between 22 healthy subjects and 35 patients with idiopathic dilated cardiomyopathy (IDC). Although cerebral oxyhemoglobin increased during exercise in most of the healthy subjects, oxyhemoglobin decreased during exercise in 15 of 35 patients with IDC. Cerebral oxygenation during exercise and exercise recovery was related to left ventricular function in the patients with IDC.

A wide range of baroreflex stimulation does not alter forearm blood flow

The contribution to the regulation of forearm blood flow (FBF) by different baroreceptor populations has previously only been studied over a limited range of stimuli. Therefore, FBF and R-R interval were recorded during neck suctions and neck pressures ranging from -60 to +40 mmHg. The change in R-R interval (DeltaR-R) during neck suction was significantly increased at each stage when compared to the control ( P<0.05). DeltaR-R did not show any significant change during any of the neck pressure stages ( P>0.05). Suction or pressure applied to the neck did not elicit any significant changes in FBF when compared to the control ( P>0.05). These data show that widening the range of applied stimuli to carotid sinus baroreceptors does not induce a change in FBF. However, the small transient changes reported previously cannot be discounted.

Cerebral Oxygenation During Exercise in Cardiac Patients

BACKGROUND

Until recently, compensatory mechanisms have been believed to regulate adequately cerebral blood flow in humans. However, this has been called into question by a series of new investigations suggesting that patients with left ventricular dysfunction suffer from cerebral hypoperfusion. We compared cerebral oxygenation during incremental exercise between patients with valvular heart disease and normal subjects.

METHODS

Thirty-three patients with valvular disease and 33 normal subjects performed a symptom-limited incremental exercise test using a cycle ergometer. Oxyhemoglobin at the forehead was continuously monitored during exercise using near-infrared spectroscopy. Respiratory gas measurements were performed on a breath-by-breath basis.

RESULTS

The increase in oxyhemoglobin during exercise was significantly lower in the patients with valvular disease than in normal subjects. The change in oxyhemoglobin during exercise (DeltaO(2)Hb) at the forehead was negatively correlated with the slope of the increase in minute ventilation to the increase in carbon dioxide output (DeltaE/DeltaCO(2)), and positively correlated with the peak oxygen uptake (O(2)), gas exchange threshold (GET), and slope of the increase in O(2) to the increase in the work rate (DeltaO(2)/DeltaWR). Among the patients with valvular disease, 15 patients showed a decrease in oxyhemoglobin at the forehead during exercise. When compared with the patients with increased oxyhemoglobin, those with decreased levels exhibited a higher DeltaE/DeltaCO(2) and a lower peak O(2), GET, and DeltaO(2)/DeltaWR.

CONCLUSIONS

The present findings strongly suggest that cerebral oxygenation during exercise is dependent on the cardiovascular and pulmonary systems. The study also indicated the presence of cerebral hypoperfusion during exercise in cardiac patients whose cardiac output fails to increase normally.

Effects of dobutamine on critical capillary PO(2) and lactic acidosis threshold in patients with cardiovascular disease

BACKGROUND

Muscle capillary PO(2) has been found to reach a minimal value, ie, a critical capillary PO(2), in the midrange of work capacity in patients with cardiovascular disease. However, it is not known if the critical capillary PO(2) can be influenced by a change in blood flow response to exercise. This study was carried out to determine the effect of changing the blood flow response to exercise, using low-dose infusion of dobutamine, on muscle end-capillary PO(2) (as approximated by femoral vein PO(2)), lactate concentration, oxygen uptake (O(2)), and the relation among these variables.

METHODS

Eleven male patients with coronary artery disease performed an incremental exercise test on a cycle ergometer with and without continuous infusion of dobutamine, 6 microg/kg/min. Respiratory gas analysis was performed on a breath-by-breath basis; femoral vein blood was sampled every minute through a percutaneous catheter.

RESULTS

Dobutamine increased resting O(2) and O(2) at the lactic acidosis threshold (LAT) but not peak O(2). The femoral vein PO(2) rapidly decreased toward a minimal value with increasing work rate (O(2)) irrespective of the infusion of dobutamine. After reaching its nadir (critical PO(2)), femoral vein lactate began to increase without further decrease in PO(2). Infusion of dobutamine significantly increased femoral vein resting PO(2) (27.4 +/- 4.9 mm Hg vs 32.5 +/- 3.8 mm Hg) and critical PO(2) (20.5 +/- 1.5 mm Hg vs 21.9 +/- 1.7 mm Hg), but not the PO(2) at peak O(2) (22.1 +/- 3.3 mm Hg vs 22.0 +/- 2.9 mm Hg).

CONCLUSIONS

Infusion of dobutamine was found to raise the critical PO(2) and LAT but not peak O(2). These findings suggest that some of the acute increase in blood flow induced by dobutamine infusion benefits exercising muscle by increasing capillary PO(2), thereby delaying the onset of lactic acidosis.

Prognostic significance of cardiopulmonary exercise testing for 10-year survival in patients with mild to moderate heart failure

Although a number of studies have investigated the prognostic significance of exercise variables, they have focused only on short-term prognosis in relatively severe heart failure. This study was carried out to determine whether the indices obtained during cardiopulmonary exercise testing have prognostic significance during a 10-year follow-up in mild to moderate heart failure. Three hundred and sixty-four consecutive patients with cardiac disease performed 4 min of 20-W warm-up, followed by a symptom-limited incremental exercise test on a cycle ergometer. In addition to the measurements of peak oxygen uptake (VO2) and gas exchange (anaerobic) threshold, the time constant of VO2 kinetics during the onset of warm-up exercise was calculated using a single exponential equation. Data on mortality were available for follow-up in 260 patients. After 3,331+/-610 days of follow-up, 29 cardiovascular-related deaths occurred. The time constant of VO2 in the nonsurvivors was 76.7+/-43.3 s and was significantly prolonged compared with that of survivors (55.3+/-30.6 s, p=0.001). Peak VO2 and gas exchange threshold were both significantly lower in nonsurvivors than in survivors. Kaplan-Meier survival curves for 10 years of follow-up demonstrated a survival rate of 89.0% for patients with a normal VO2 time constant (< 80 s) and 71.7% for those with a longer time constant (> or = 80 s), showing a significant difference in survival (p=0.0028). Respiratory gas parameters obtained during exercise testing, particularly the time constant of VO2 kinetics, were found to be useful for predicting long-term prognosis in patients with chronic heart failure. These results suggest that cardiopulmonary exercise testing could be more applicable in ambulatory patients with minimal symptoms or minimal functional impairment.

Improvement of exercise tolerance by single lead VDD pacemaker: evaluation using cardiopulmonary exercise test

We used a cardiopulmonary test to assess the physiological benefit of single lead VDD pacing in ten patients (six men, four women; aged 32-84 years, mean 69 years) with atrioventricular block. Maximal symptom-limited treadmill exercise test using a ramp protocol was performed under VDD and VVIR or VVI pacing (VVI) in random sequence. The pacemaker was then programmed to the VDD mode, and Holter ECG was recorded in nine patients. Compared with findings during the VVI, the VDD mode had a greater chronotropic response (mean maximal heart rate, VDD 106 +/- 17 beats/min vs VVI 79 +/- 19 beats/min, P = 0.03), and was associated with prolongation of exercise duration (VDD 11.2 +/- 2.9 minute vs VVI 10.5 +/- 3.1 minute; P = 0.01), and the onset of anaerobic threshold at a higher oxygen uptake (VDD 12.4 +/- 3.4 mL/min per kilogram vs VVI 10.0 +/- 2.1 mL/min per kilogram; P < 0.01). Atrial sensing was recognized in almost all normal sinus P waves for all cases examined using Holter ECG. Thus, chronotropic response during exercise by VDD pacemaker improved exercise tolerance, indicating that a VDD pacemaker might be useful for patients requiring physical activity.

Percutaneous transluminal coronary angioplasty improves oxygen uptake kinetics during the onset of exercise in patients with coronary artery disease

STUDY OBJECTIVES

Although percutaneous transluminal coronary angioplasty (PTCA) is known to have beneficial effects on exercise capacity, its effects on the cardiovascular response during the onset of exercise have not been clarified. The present study was undertaken to determine the effects of PTCA on the kinetics of oxygen uptake (VO(2)) during constant-work-rate exercise in patients with coronary artery disease, as well as on their indexes of maximal work capacity.

METHODS

Seventeen patients with coronary artery disease who received successful PTCAs performed a 50-W constant-work-rate exercise test for 6 min and a symptom-limited incremental exercise test both before and 4 months after the PTCA procedure. VO(2) was calculated from breath-by-breath analysis of respired gases. The time constant of VO(2) kinetics during the onset of 50-W exercise was determined by fitting a single exponential function to the VO(2) response.

RESULTS

In 14 patients without coronary restenosis, the time constant of VO(2) kinetics was significantly shortened from (mean +/- SD) 57.4 +/- 12.6 before PTCA to 48.2 +/- 9.5 s after PTCA (p = 0. 0035), indicating improved kinetics of the VO(2) response. In these subjects, the peak VO(2) obtained during maximal exercise testing also increased from 23.1 +/- 3.5 to 26.5 +/- 3.2 mL/min/kg, respectively (p = 0.0005). However, there was no improvement in these indexes in the patients who had restenosis after undergoing PTCA (n = 3).

CONCLUSION

Indexes of cardiopulmonary exercise testing, which reflect an efficiency of oxygen flow to the exercising muscle, can be used as an objective, noninvasive, and cost-effective guide for understanding which patients will not have coronary restenosis following PTCA.

Naloxone decreases tolerance to hypotensive, hypovolemic stress healthy humans

OBJECTIVE

In animal studies, naloxone, an opioid receptor antagonist, improves tolerance to hemorrhagic shock. The purpose of this study was to determine whether naloxone would augment tolerance to hypotensive hypovolemic stress (lower body negative pressure [LBNP]) in healthy human males.

DESIGN

This study was a repeated measures design.

SETTING

The experiments were conducted in a laboratory setting.

SUBJECTS

Eight healthy male subjects were tested. The subjects' ages were 30 +/- 4.0 yrs, height = 177 +/- 7.0 cm, and weight = 75.5 +/- 3.5 kg (mean +/- SEM).

INTERVENTIONS

Subjects underwent two LBNP exposures terminated by the onset of vasodepression. At each of the exposures, using a double-blind procedure, the subjects received an intravenous injection of either saline placebo or naloxone in a dosage totaling 0.4 mg/kg.

Effects of 'cool-down' during exercise recovery on cardiopulmonary systems in patients with coronary artery disease

The effects of 'cool-down' during exercise recovery on cardiovascular and respiratory systems have not been fully clarified. The recovery of respiratory gasses was compared in cardiac patients after maximal exercise during which subjects either performed a cool-down or rested. Twenty-one patients (61+/-10 years) with coronary artery disease performed 2 symptom-limited incremental exercise tests on a cycle ergometer: one with a cool-down and the other without during recovery from the maximal exercise test. Expired gasses were analyzed on a breath-by-breath basis throughout the test and for 6min of recovery. Without a cool-down, the ventilatory equivalent for O2 (VE/O2) increased dramatically during recovery compared with the resting values or those of peak exercise: 44.5+/-7.7 at rest, 44.0+/-10.6 at peak exercise and 63.3+/-14.5 after 2min of recovery. End-tidal PO2 (P(ET)O2) also increased significantly during recovery. However, the overshoot phenomenon of these variables was attenuated when cool-down exercise was performed during recovery. The high ratio of VE/VO2 reflects ventilation perfusion (VA/Q) unevenness and P(ET)O2 is an index of arterial PO2. Thus, it is suggested that cool-down exercise during recovery after maximal exercise testing provides beneficial effects on the respiratory system by decreasing the VA/Q unevenness and relative hyperventilation that are observed when cool-down exercise is not performed.

Effects of posture on left ventricular diastolic filling during exercise

BACKGROUND

Measuring the transmitral flow velocity with Doppler echocardiography is a useful method for evaluating left ventricular diastolic function. However, there are few data regarding the effect of posture during exercise on transmitral flow velocity.

METHODS

The transmitral flow velocity with pulsed-wave Doppler echocardiography was measured during supine and upright bicycle ergometer exercise in 10 normal young men without cardiac disease (26.7 +/- 5.5 yr).

RESULTS

The ratio of the early rapid filling wave to the atrial filling wave (E/A) was gradually decreased with increasing exercise intensity. At rest and during recovery, the E/A ratio was significantly higher (P < 0.01) in the supine position than in the upright position. This difference was caused mainly by the higher E wave in the supine position. However, E wave and E/A ratio did not differ between the upright and supine position during exercise.

CONCLUSION

Although measurement of left ventricular filling is completely noninvasive and clinically useful for evaluating diastolic function, it was found that the E/A ratio was profoundly influenced by posture and exercise intensity. These results suggest that the potential influences of posture and exercise intensity on the filling velocities should be taken into account when interpreting diastolic function by Doppler echocardiography.

Mechanism of overshoot in cardiac function during recovery from submaximal exercise in man

BACKGROUND

A sudden increase (overshoot) in the left ventricular ejection fraction during the recovery from maximal exercise has been reported in patients with coronary artery disease, but its mechanism has not been fully clarified. We investigated whether this phenomenon may occur in normal subjects, and whether it depends on the intensity of exercise.

METHODS

Thirteen normal subjects (mean [+/- SD] age, 59 +/- 8 years old) performed two levels (25 W and 50 W) of mild-intensity, constant-work-rate exercise for 6 min on a cycle ergometer. Left ventricular function was monitored continuously during the recovery from exercise using a computerized cadmium telluride detector.

RESULTS

An overshoot was observed in the ejection fraction during the first minute of recovery compared with the end-exercise value. The overshoot in the ejection fraction during recovery after the 50-W exercise was greater than that seen after the 25-W exercise. An overshoot phenomenon in stroke volume was also observed during the recovery from 50-W exercise.

CONCLUSIONS

The overshoot in cardiac function observed during the early phase of recovery, which was caused mainly by an immediate decrease in end-systolic volume, occurred even after exercise of mild intensity. This phenomenon appears to suggest the existence of a transient mismatch between cardiac contractility and afterload reduction during the recovery from mild-intensity exercise, even in normal subjects.

The relation between religiosity, selected health behaviors, and blood pressure among adult females

BACKGROUND

This study examined the association between blood pressure (BP), selected health behaviors, and various dimensions of religiosity among females.

METHODS

Data were obtained on 112 females who were at least 35 years of age and of Judeo-Christian faith. Resting BP measures were taken with an automated sphygmomanometer, height and weight were measured to determine body mass index (BMI), and intermediate health variables (e.g., physical activity, smoking, diet, and alcohol consumption) were measured by questionnaire. A multifactorial questionnaire was used to assess various dimensions of religiosity. Multiple regression path analyses were conducted to determine the direct and indirect effects of religiosity on BP with age and BMI controlled statistically.

RESULTS

The direct effects of religiosity on SBP and DBP were more substantial than the indirect effects through the intermediate health variables, suggesting that religiosity may be associated with lower levels of BP via a direct pathway, such as improving the ability to cope with stress. In general, DBP was more influenced by religiosity than SBP and the dimensions of "intrinsic religiosity" and "religious coping" were most influential. Results also indicated that "religious experiences" may exert a greater beneficial effect on DBP in older (50-80 years) age groups.

CONCLUSIONS

These results support a direct relationship between religiosity and BP, rather than an indirect effect through intermediate health behaviors.

Delayed kinetics of oxygen uptake during recovery after exercise in cardiac patients

PURPOSE

Little is known about cardiovascular responses during recovery from exercise in patients with cardiovascular disease. The aim of this study was to determine the time constants of the kinetics of oxygen uptake and heart rate during recovery from exercise and to evaluate the influence of resting cardiac function on these kinetics in patients with left ventricular dysfunction.

METHODS

A moderate exercise test was performed by 40 patients (57+/-10 yr old) with prior myocardial infarction at a constant work rate (40+/-8 W) for 6 min on a cycle ergometer. The time constants of oxygen uptake and heart rate during 6 min of recovery were compared in patients whose left ventricular ejection fractions were > or =35% (group 1, N = 20) and those with ejection fractions <35% (group 2, N = 20).

RESULTS

The time constant of the decrease in oxygen uptake during exercise recovery was significantly prolonged (oxygen requirement was increased) in group 2 compared with group 1. Heart rate during recovery was consistently higher, and its time constant was prolonged in group 2 compared with group 1. The time constant of oxygen uptake was positively correlated with the time constant of heart rate.

CONCLUSION

The recovery of oxygen uptake after exercise was significantly delayed, associated with delayed recovery of heart rate, in patients with severely impaired left ventricular function.

Effects of isosorbide dinitrate on oxygen uptake kinetics in cardiac patients

PURPOSE

Although nitrates are known to improve indices of exercise capacity in patients with coronary artery disease, their effects on oxygen uptake kinetics during the onset of exercise have not been clarified. We evaluated the acute effects of isosorbide dinitrate on the kinetics of oxygen uptake during the onset of exercise at a constant work rate in patients with coronary artery disease.

METHODS

We studied 14 patients with coronary artery disease who performed 6 min of low-intensity exercise at a constant work rate on a cycle ergometer 30 min after oral administration of 10 mg of isosorbide dinitrate or placebo in a double-blind, crossover manner. Oxygen uptake was calculated from breath-by-breath analysis of respired gases. The time constant of oxygen uptake kinetics during the onset of exercise was determined by fitting a single exponential function to the oxygen uptake response.

RESULTS

Heart rate was significantly increased at rest, and systolic blood pressure was significantly decreased both at rest and during exercise after administration of isosorbide dinitrate. The time constant of oxygen uptake was significantly shorter (the kinetics were faster) after administration of isosorbide dinitrate (39.4+/-10.1 vs 44.5+/-10.5 s, P = 0.038).

CONCLUSIONS

Isosorbide dinitrate was found to speed the kinetics of the increase in oxygen uptake during constant work-rate exercise. The time constant of oxygen uptake, which reflects the rapidity of cardiovascular adaptation at the onset of exercise, seems to be a useful parameter of the effectiveness of therapy in patients with coronary artery disease.

Blood pressure measurement during exercise: a review

This review summarizes research dealing with the validity of commonly used methods for measuring systemic blood pressure during exercise. Arterial blood pressures measured from within peripheral arteries exaggerate systolic blood pressures because of wave form reflection but provide representative mean and diastolic pressures of the central arterial circulation. Manual and automated sphygmomanometry are the best noninvasive indirect methods of blood pressure measurement to estimate ascending aorta systolic pressures; however, both methods significantly underestimate diastolic pressures at rest and during exercise. The error in diastolic pressure measurement increases with increasing exercise intensity. The accuracy of many indirect noninvasive devices for blood pressure measurement at rest and during exercise can be questioned because of the use of unsuitable criterion methods. Ascending aorta pressures should ideally be used as a gold standard or criterion method for blood pressure measurement during exercise and instrument/method validation. However, given the constraints of varied criterion standards and current recommendations for blood pressure measurement, the following units were found to be acceptable devices for measuring systolic blood pressure during exercise: Accutracker II, A&D TM 2421, Colin 630 (auscultation), Critikon 1165, and possibly the Paramed 9350.

Blood pressure responses to acute exercise in type A and B females and males

Cardiovascular responses to moderate steady-state exercise were studied in Type A and Type B males and females. Eighteen men and 17 women, ages 20 to 40 years, were chosen for Type A (males = 10, females = 10) and Type B (males = 8, females = 7) groups by means of the Jenkins Activity Survey (JAS). Subjects exercised on a electronic cycle ergometer at 60% O2peak for 20 min. Repeated measures analysis of variance (ANOVA) showed a significant Time (F(8,17) = 16.1, p < 0.001) and Group x Sex interaction (F(1,24) = 7.84, p < 0.01), with no differences evident between the male systolic blood pressures (SBPs), but an elevation in the SBP of the Type A female subject. SBP between all males and females were also significantly different (F(1,24) = 68.8, p < 0.0001). Males showed a greater SBP throughout the resting, exercise, and recovery time intervals when compared to females as a group, diastolic blood pressures (DBP) showed a significant Time effect (F(8,17) = 11.8, p < 0.0001) with a significant Time x Group x Sex interaction (F(8,17) = 3.1, p < 0.02). Significant Sex effects (F(1,24) = 12.4, p < 0.002) and a marginal Group x Sex interaction were also observed (F(1,24) = 3.67, p < 0.067), with Type B females having the greatest reduction in DBP at 15 min (59.0 +/- 5.6 vs. 71.7 +/- 3.2 mmHg) and 20 min (50.0 +/- 3.3 vs. 67.3 +/- 3.9 mmHg) or exercise when compared to Type As. There were significant DBP differences between males and females throughout rest, at 5 and 20 min of exercise, and in both recovery time periods. The data only reveal significant differences in DBP between Type A and B males at 20 min of exercise [64.2 +/- 3.3 (A) and 72.6 +/- 1.2 (B) mmHg]. No significant Group main effect was evident. These data suggest that hemodynamic and other physiological responses to exercise in females, particularly Type A, vary from males according to behavioral types associated with differing physiology.

The equilibrium CO2 rebreathing method does not affect resting or exercise blood pressure

The equilibrium CO2 rebreathing technique has been widely used for the noninvasive determination of cardiac output. Recently, several investigators have used this technique in conjunction with auscultatory blood pressure measurements to calculate total peripheral resistance. To examine the validity of this approach, we attempted to determine whether the CO2 rebreathing procedure has a significant effect on blood pressure. The participants in the present study were 10 male subjects, 24 +/- 1 yr of age (mean +/- SE). Each subject performed two trials-one with CO2 rebreathing and one without. Both trials consisted of three stages (rest, 25%, and 50% VO2peak), each stage lasting 15 min. During the rebreathing trial, the CO2 rebreathing technique was administered at 10 min into each stage. There were no statistically significant differences in the heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure responses between the two trials. These results indicate that the equilibrium CO2 rebreathing technique does not alter auscultatory blood pressures at rest and during exercise up to intensities of 50% VO2peak.

Effects of nicorandil on kinetics of oxygen uptake at the onset of exercise in patients with coronary artery disease

The beneficial effects of coronary vasodilators on exercise capacity in patients with angina pectoris are well known. However, their effects on oxygen uptake (VO2) kinetics at the onset of exercise have not been elucidated. The present study was undertaken to determine the acute effects of nicorandil, a newer coronary vasodilator, on the kinetics of VO2 at the onset of exercise in patients with ischemic heart disease. Ten patients with significant coronary stenosis performed constant mild-intensity cycle exercise (32 +/- 3 W) for 6 minutes after oral administration of 10 mg of nicorandil or an identical placebo in a double-blind, crossover manner. Nicorandil had no effect on resting heart rate, blood pressure, or VO2. However, the time constant for the increase in VO2 during constant work rate exercise was significantly shorter (the kinetics of VO2 were faster) after administration of nicorandil than after placebo (46.5 +/- 13.3 vs 51.1 +/- 11.9 seconds; p = 0.039). The increase in VO2 at 6 minutes compared with 3 minutes of constant work, which reflects the VO2 kinetics, also was reduced with nicorandil (3.8 +/- 37.9 vs 27.5 +/- 27.1 ml/min; p = 0.022). Nicorandil was found to increase the rate of VO2, increase during the onset of constant work rate exercise, probably as a result of an improved response in cardiac output. Analysis of VO2 kinetics provides new and useful parameters for the evaluation of circulatory adjustments at the onset of exercise in patients with ischemic heart disease.

Physiological responses to 90 min of simulated dinghy sailing

A dinghy sailing race protocol was developed from video analysis of elite Laser class sailors competing in fairly windy (> 12 knots) national level races. A dinghy sailing ergometer was constructed for use with a 90 min protocol. Subjects watched a video of a Laser dinghy skipper sailing (on-water) according to the protocol while themselves hiking (leaning out) from the ergometer and simulating their normal on-water movements in tandem with the video. This simulation was used to examine physiological responses to dinghy sailing and factors correlated with hiking performance in 10 of Australia's top 30 Laser dinghy sailors. Simulated dinghy sailing elicited a large blood pressure response but a low rate of aerobic and anaerobic metabolism. During the 20 min upwind legs, the mean (+/- S.E.M.) systolic and diastolic blood pressures were 172 +/- 18 and 100 +/- 14 mmHg respectively, and mean arterial blood pressure (MABP) was 123 +/- 14 mmHg. Oxygen uptake during the simulated upwind legs was 1.12 +/- 0.22 1 min-1. Both blood pressure and VO2 were significantly lower during the 12 min reaching legs. The mean of the blood lactate concentrations measured 1 min following each of the upwind legs was 2.32 +/- 0.81 mM. Isometric knee extension strength (at 130 degrees) and the length to which subjects set the hiking strap on the ergometer were moderately related to upwind hiking performance (knee extension strength and upwind hiking strap tension, r = 0.62; hiking strap length and upwind righting moment, r = 0.66; both P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Capacity for vasodilatation in the forearms of manual and office workers

The aim of the present study was to investigate whether occupational physical work using the arms would have a local training effect on the capacity for vasodilatation in the forearm. The subjects were 13 installation workers, and 13 office workers, who were similar in age, height, and body mass. The installation workers were exposed to heavy manual tasks during most of their workshift, whereas the office workers did no heavy manual exercise. The index of forearm capacity for vasodilatation was the plethysmograph flow response after 10 min of arterial occlusion (240 mmHg, 32 kPa). Systolic and diastolic blood pressure, and skin red cell flux (laser-Doppler) were determined together with the blood flow. In both groups, the dominant arm had significantly higher circumference and volume compared to the nondominant arm, whereas handgrip strength was similar for both the arms. The manual workers had greater volumes in both arms in comparison to the office workers, but handgrip strength did not differ between groups. In both groups, the peak forearm vascular conductance was higher in the dominant arm compared to the nondominant arm. In both forearms, the manual workers exhibited significantly higher peak blood flow, and peak vascular conductance than the office workers. No significant difference in skin blood flow was seen between the groups or arms. In conclusion, the forearms of the manual workers had a greater capacity for vasodilatation compared to the office workers suggesting a local vascular training effect due to frequent exposure to heavy physical work using hands.

Evaluation of the Colin STBP-680 at rest and during exercise: an automated blood pressure monitor using R-wave gating

The application of automated blood pressure measurement during exercise has been limited by inaccuracies introduced by the effects of accompanying motion and noise. We evaluated a newly developed automated blood pressure monitor for measuring exercise blood pressure (Colin STBP-680; Colin, San Antonio, Texas, USA). The STBP-680 uses acoustic transduction with the assistance of the electrocardiogram R-wave to trigger the sampling period for blood pressure measurement. The automated monitor readings were compared with simultaneous technician mercury sphygmomanometric readings in the same arm. Blood pressure was measured in 18 men at rest and during exercise at 40% VO2 peak, (low intensity), 70% VO2 peak (moderate intensity) and VO2 peak (high intensity) on the cycle ergometer. Mean(s.d.) systolic blood pressure difference between the automated monitor and mercury manometer readings at rest and during exercise at low, moderate and high work intensities were 3(0) mmHg, 3(2) mmHg, 1(1) mmHg, and 0(11) mmHg respectively (analysis of variance; P > 0.05). Resting diastolic blood pressure obtained with the STBP-680 was similar to the mercury manometer readings (78(10) versus 81(7) mmHg (P > 0.05). Exercise diastolic pressure at the low level of work intensity was almost identical between the automated monitor and mercury manometer readings (64(8) versus 65(10) mmHg (not significant)). Diastolic blood pressure readings between the STBP-680 and mercury manometer showed a greater difference at the moderate and high workloads (11 mmHg and 9 mmHg, respectively), but this difference was not significant (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobic metabolism as an indicator of aerobic function during exercise in cardiac patients

To determine whether patients with heart disease depend more than normal subjects on anaerobic metabolism to perform the same level of exercise, the anaerobic threshold, slope of the increase in carbon dioxide output with respect to oxygen uptake (delta VCO2/delta VO2) and the slope of the increase in oxygen uptake with respect to the increase in work rate (delta VO2/delta WR) both below and above the anaerobic threshold during exercise were evaluated. A total of 106 patients with chronic heart disease and 42 healthy subjects performed a symptom-limited incremental exercise test in a ramp pattern on a cycle ergometer. Peak oxygen uptake was significantly lower in the patients with heart disease than in the normal subjects. The anaerobic threshold, which was 20 +/- 4.6 ml/min per kg in normal subjects, decreased significantly with progressing severity of functional class: 16 +/- 2.4, 14.1 +/- 2.5 and 11.3 +/- 1.5 ml/min per kg, respectively, in patients in class I, class II and class III. The slope of delta VO2/delta WR, which represents the degree of aerobic metabolism, was also decreased both below and above the anaerobic threshold with increasing severity of heart disease. delta VCO2/delta VO2 below the anaerobic threshold was approximately 0.9 (p = NS between normal subjects and patients). However, delta VCO2/delta VO2 above the anaerobic threshold became steeper with increasing severity of heart disease: 1.37 +/- 0.17 in normal subjects versus 1.55 +/- 0.24, 1.67 +/- 0.3 and 1.8 +/- 0.35 respectively, in patients in functional class I, class II and class III.(ABSTRACT TRUNCATED AT 250 WORDS)