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PubMed1997

Oxygen-15-water PET assessment of muscular blood flow in peripheral vascular disease.

UNLABELLED: To assess quantitatively regional nutritive muscular blood flow in patients with peripheral vascular disease (PVD), we evaluated the utility of PET with 15O-water. METHODS: Eight healthy volunteers and 16 patients with angiographically proven PVD were studied. Regional blood flow of the calf was measured with 15O-water PET during rest, after intra-arterial infusion of prostaglandin E1 and during ergometry. The studies were quantified using a one tissue compartment model. RESULTS: Normalized mean tracer uptake from 15-60 sec correlated closely (r = 0.98) with absolute blood flow. Scan times longer than 90 sec were required to determine blood flow reliably. The flow values were overestimated by 2% if arterial blood volume was neglected or if the input function delay was corrected globally for parametric imaging. Mean blood flow of calf muscles at rest did not differ significantly between patients (0.017 +/- 0.006 ml/min/ml) and control subjects (0.018 +/- 0.010 ml/min/ml). In PVD patients, blood flow increased by 100% after intra-arterial infusion of PGE1 in the respective leg. In the control subjects, average flow increased by a factor of six during exercise. The increase was more pronounced in the extensor muscles (0.182 +/- 0.031 ml/min/ml) than in flexor muscles (0.121 +/- 0.045 ml/min/ml). Due to the specific type of ergometry, superficial flexors exhibited higher flow values than the profound ones. CONCLUSION: PET with 15O-water enables reliable determination of regional nutritive skeletal muscle blood flow for research and clinical applications in patients with PVD.

Adult↗
PubMed1996

[Dynamic exercise tests in the assessment of rehabilitation in patients with myocardial infarction].

176 patients with myocardial infarction were subjected to a sequence of tests: an original gravimetric test on the disease day 7-10, bicycle ergometry on day 12-20, repeated bicycle ergometry on days 30-35 and 100-120. The results of the investigations performed in different times were interrelated. This helped to make accurate prognosis of recovering ability in 85% of patients. This system of dynamic control demonstrated that the greatest positive effects on exercise tolerance are reached in combined use of intravenous blood radiation with He-Ne laser and combined chemotherapy. Nitroglycerin+heparin combination is the least effective. Nitroglycerin+heparin in combination with metabolism correctors is of moderate efficacy.

Adult↗
PubMed1996

[Initial clinical experiences with indirect myocardial revascularization--free skeletal muscle transplantation for induction of epimyocardial neovascularization].

Patients with multiple and peripherial coronary stenosis are not suitable for direct coronary artery surgery. For these patients a new surgical myocardial revascularization was developed. This new surgery was adopted on 5 patients from May 1993 through May 1995. The operation consisted in the grafting of a free skeletal muscle flap onto the anterior wall of the heart (musculus-latissimus-dorsi). The flap artery was implanted into the aorta, the venous flow was directed into the right atrium. All patients were about 3 weeks after the intervention free from angina. The postoperative bicycle ergometry showed no signs of ischemic ST-segment changes, meanwhile the preoperative ergometry evinced signs of ischemic ST-segment changes in almost all patients. Angiographically a patent anastomosis of the flap artery implanted into the aorta was found as well as a good contrast of the graft. Thus, "indirect myocardial revascularization" may be a surgical alternative treatment for patients suffering from therapy refractory ischemic heart disease.

Aged↗
PubMed1979

[Clinical study of the antiarrhythmic action of Mexityl in ventricular disorders of the cardiac rhythm].

The anti-arrhythmic activity of mexitil was studied in 36 patients with frequent, prognostically unfavourable ventricular extrasystoles of various etiology. Quantitative and qualitative assessment of rhythm disorders was accomplished by bicycle ergometry and ECG recording for 24 hours by means of portable monitors. The disorders of rhythm were appraised prior to treatment, during mexitil medication in daily doses of 750--1200 mg/24 hrs administered for 3--5 days, and against the background of placebo. The effect of a single 250 to 600 mg dose of mexitil was appraised by monitoring the ECG for three and a half hours. The concentration of mexitil in blood plasma and saliva was tested by gas-fluid chromatography. A positive effect of mexitil treatment manifested in complete correction of ventricular extrasystoles or the reduction of their number by more than half and complete elimination of group extrasystoles and paroxysms of ventricular tachycardia was produced in 66 per cent of patients according to the daily ECG monitoring finds and in 76 per cent of patients according to the results of bicycle ergometry. The antiarrhythmic effect developed 62 minutes, on the average, after oral administration of a single 250--600 mg dose of mexitil and lasted 5--8 hours and more. The therapeutic concentration of mexitil ranged from 0.6 to 0.9 micrograms/ml in blood plasma and from 10.3 to 15.8 micrograms/ml in saliva. In 36 per cent of patients side effects (mainly muscular tremor, lassitude and headache) were noted. It is concluded that mexitil possesses high anti-arrhythmic activity in ventricular extrasystole. To avoid side effects it is recommended to begin treatment in a dose of 250 mg given three times daily, and if necessary gradually increase the single dose to 400 mg and the daily dose to 1200 mg.

Adult↗
PubMed1997

The cognitive, subjective, and physical effects of a ginkgo biloba/panax ginseng combination in healthy volunteers with neurasthenic complaints.

We evaluated the effects of a Ginkgo biloba/ginseng combination on cognitive function in this 90-day, double-blind, placebo-controlled, parallel-group study. Sixty-four healthy volunteers (aged 40 to 65 years), selected on the basis of fulfilling the ICD-10 F48.0 criteria for neurasthenia, were assigned randomly to four equal dosing groups, receiving 80, 160, or 320 mg of the combination b.i.d. or placebo. Assessments were performed on the day before dosing, and again at Days 1, 30, and 90 at 1 hour after the morning dose and 1 hour after the afternoon dose. The assessments included the Cognitive Drug Research (CDR) computerized assessment system, the Vienna Determination Unit, cycle ergometry, and various questionnaires. The treatments were well tolerated by all volunteers. On Day 90 at 1 hour post morning dosing, dose-related improvements were seen on the CDR tests, the 320 mg dose being significantly superior to placebo. These effects, however, were reversed 1 hour after the afternoon dose, possibly suggesting that a longer inter-dosing interval would be preferable. The 80-mg dose produced a significant benefit on the ergometry assessment of heart rate at maximum load. There were also several supporting changes from other assessments, including an advantage of 320 mg over placebo on the global score from the Symptom Checklist-90-revised (SCL-90-R) at Day 90.

Adult↗
PubMed1998

[Pacemaker therapy in heart failure].

Drug therapy is the standard therapy for heart failure. The current state of the art does not permit pacemaker therapy as a general recommendation for left ventricular failure. Numerous controversial reports have been published on the success of pacemaker therapies for congestive heart failure. Iskandrian reported on tachycardiac atrial stimulation in 1986. Since 1990 several papers have been published on DDD-pacemakers with short AV-time. From the data available to us, congestive heart failure is generally not considered a new pacemaker indication. In carefully selected patients, however, an improvement in hemodynamics as well as in NYHA-classification can be expected, both in acute cases and on a long-term basis. In 16 patients Hochleitner demonstrated a significant increase in left ventricular ejection fraction, a significant drop in NYHA-classification, heart size and an increase in systolic and diastolic blood pressure. Using echocardiography Brecker showed a decrease in mitral regurgitation, an increase in ventricular filling time and, by means of ergometry, a major increase in cardiac output. The hypothesis for the working mechanism is that a shorter AV-time optimizes the time needed for AV-contraction, thereby reducing mitral regurgitation, lengthening ventricular filling time and thus increasing ejection fraction. Identification of the patients to whom this hypothesis can be applied is difficult but imperative. The optimal AV-time for each patient must be established on an individual basis using echocardiography, Doppler sonography and ergometry and must be finetuned in follow-up controls. Optimization of AV-time in patients with the classic indications for a pacemaker as well as a combination of cardioverters and DDD-pacemakers should be aimed for in patients with congestive heart failure and high NYHA-classification.

Atrioventricular Node↗
PubMed1998

The role of epidermal growth factor in platelet-endothelium interactions.

The objective of this study was to determine whether endogenous EFG released after submaximal physical exercise, affects platelet-endothelium interactions. Sixteen healthy male volunteers, aged 23-26 years, were submitted to a submaximal bicycle ergometry test. Blood for determination of EGF concentrations, platelet function studies (concentrations of beta-TG, PF4 and TXB2) and endothelium activity (LTC4 and endothelin-1,2 concentrations) was taken via an intravenous catheter before starting exercise and 15, 30 and 60 min after. A similar scheme was followed to investigate changes in the same parameters induced by a slow intravenous infusion of 0.3 mg/kg b.w. phentolamine (an alpha-adrenergic blocker) before exercise. Plasma concentrations of EGF and the markers of platelet function-beta-TG and PF4 as well as LTC4 concentrations increased only 15 min following exercise. The concentrations of TXB2, and endothelium-1,2 were almost unchanged 15 min after the submaximal bicycle ergometry test. Phentolamine markedly decreased the EGF concentrations in plasma (15 min following exercise) while at 30 and 60 min after exercise it had no effect on this parameter. No significant changes in concentrations of beta-TG, PF6, LTC4 and endothelin-1,2 after phentolamine infusion were found. These results show that increase of plasma EGF following exercise was accompanied with increase of beta-TG, PF4 and LTC4 concentrations. Inhibition of alpha-adrenergic receptors with phentolamine abolished the exercise-induced increase in plasma EGF concentration. The findings suggest that endogenous EGF may affect the platelet function and changes the reactivity of the vascular endothelium.

Adult↗
PubMed1998

Predicting aerobic power in children. A comparison of two methods.

OBJECTIVE: To compare the accuracy of two equations for predicting VO2max of children using submaximal cycle ergometry. EXPERIMENTAL DESIGN: Repeated measures comparing treadmill measured maximal aerobic power (VO2max) with two methods of predicting VO2max using cycle ergometry testing. PARTICIPANTS: Thirty-three children (15 boys and 18 girls) aged 7-13 years served as subjects. MEASURES: Each child completed a treadmill graded exercise test (GXT) to volitional fatigue to assess VO2max. Each child also completed a progressive 9-min, three-stage, submaximal cycle ergometer test. Heart rates obtained during the last minute of each stage of the ergometer test were used to predict VO2max. Predictions were based on a gender-specific modification of the PWC170 (PWCGS) and a modification of the PWC195 using a 1.17 correction factor and an age and gender-adjusted estimate of resting metabolic rate. RESULTS: The correlations between both submaximal tests and the GXT were significant (p < 0.001); however, the correlation between the GXT and the PWC195 equation (r = 0.807) was higher than the correlation between the GXT and the PWCGS equation (r = 0.658). Analysis indicated that the PWCGS equation significantly underestimated the VO2max compared to either the GXT or PWC195 (GXT = 45.0 +/- 7.1, PWC195 = 44.7 +/- 6.2, PWCGS = 42.7 +/- 5.8 ml/kg/min; p < 0.01). CONCLUSIONS: These results suggest that although the gender-specific PWCGS method is easier to compute and may be acceptable, the modified PWC195 method is a more accurate estimate of VO2max in children.

Adolescent↗
PubMed1999

Clinical utility and safety of exercise testing in patients with hypertrophic cardiomyopathy.

BACKGROUND: Exercise testing has long been employed in patients with hypertrophic cardiomyopathy (HCM), although concerns have constantly been expressed regarding its safety. This study reviews a large number of exercise tests performed in a community-based population with HCM, in terms of safety and clinical utility. METHODS: We analyzed a total of 243 maximal symptom-limited cycloergometer exercise tests performed at our institution in 138 patients with HCM (age 42 +/- 14 years, M/F 99/39), who were followed systematically for 9.4 +/- 6.5 years. RESULTS: In none of the 243 exercise tests did cardiac arrest, hemodynamic collapse or malignant arrhythmia occur, although 53 of the study patients (38%) had > or = 1 risk factors including previous cardiac arrest, recurrent syncope, malignant family history and resting left ventricular outflow obstruction. Early termination of the test was necessary in only 8 patients due to symptomatic hypotension with dizziness, but none had syncope. Mean predicted functional capacity achieved by the study group was 77 +/- 22%. Poor performance (< 60% of predicted functional capacity) was observed in 32 patients (23%), and it was associated with a NYHA functional class > 1 and an abnormal blood pressure response to exercise. Non-malignant arrhythmias occurred in 41 patients (30%), including multiple premature ventricular beats (PVB), paroxysmal atrial fibrillation, non-sustained ventricular (NSVT) and supraventricular tachycardia. The combined presence of multiple exercise-induced PVB and NSVT on Holter ECG had a 14% positive but a 97% negative predictive value for sudden death or cardiac arrest. CONCLUSIONS: 1) Exercise testing is safe in a community-based population of patients with HCM, and provides useful information regarding functional capacity, efficacy of treatment, blood pressure response to exercise and inducible ischemia. Thus, ergometry should routinely be included in the standard evaluation and follow-up protocols of HCM patients. 2) Conversely, the utility of ergometry in the evaluation of the arrhythmic risk in HCM patients appears to be limited to the identification of low-risk patients.

Adult↗
PubMed2003

Three-minute step test to assess exercise capacity in children with cystic fibrosis with mild lung disease.

The information obtained from a simple submaximal test (the 3-min step test) was compared with that from a maximal cycle ergometry study, in a group of children with CF with relatively mild abnormalities of lung function (FEV(1) > 50% predicted). Nineteen subjects with CF undertook both exercise tests on the same day. Measurements included heart rate (HR), oxygen saturations (SaO(2)), visual analogue score of perceived breathlessness (VAS), 15-count breathlessness score (15c), and peak oxygen consumption (VO(2)). There were significant differences in the median changes in HR and VAS during the cycle test compared to the step test, 78 vs. 46 beats per minute (P < 0.05) and 51 mm vs. 42 mm (P < 0.05), respectively. There were no differences between median changes in 15c and SaO(2), but 3 subjects had significant desaturations (>4%) during the cycle test only. Significant exercise desaturations may occur in mild CF lung disease and will not be detected by a 3-min step test. The 15c did not discriminate between a maximal and a submaximal test, and was less useful than VAS. Important information may be missed by the step test which is detected by more complex exercise tests.

Adolescent↗
PubMed1993

Influence of posture on arm exercise tolerance and physiologic responses in persons with spinal cord injured paraplegia.

This study compared metabolic and cardiopulmonary responses to incremental supine and upright sitting arm crank ergometry (ACE) in nine men with spinal cord injured paraplegia ranging from T1-T5. Both tests consisted of continuous graded ACE from rest to volitional fatigue on a modified electronically braked cycle ergometer with the work rate increased by 8.2 W.min-1. No significant differences (P > 0.05) existed for peak ACE power output (W), oxygen uptake, pulmonary ventilation, respiratory exchange ratio, and O2 pulse between the two tests. Heart rate and O2 pulse responses at six submaximal work rates representing 0-58% peak W were also not significantly different between postures. These data indicate that ACE tolerance in persons with high-lesion paraplegia was not enhanced when ACE was performed in the supine posture.

Adult↗
PubMed2000

Relationships between physical activity, physical fitness, muscle strength and nutritional state in 5- to 11-year-old children.

The purpose of the present study was to assess different aspects of physical activity and fitness in order to develop a basis for sport programmes for overweight and obese children. Eighty-eight prepubertal children (49 boys, 39 girls, 4.8-11.4 years old, 61% obese, 14% overweight and 25% normal weight) were examined. Body composition was assessed by combined use of anthropometrics and bioelectrical impedance analysis. Resting energy expenditure (REE) and total energy expenditure (TEE) were measured by indirect calorimetry (IC) and individually calibrated 24-h heart rate (HR) monitoring, respectively. Activity-related energy expenditure (AEE) and physical activity level (PAL) were calculated from TEE and REE. Fitness [assessed by O2-pulse, respiratory exchange ratio (RER) at submaximal work intensities] was determined by ergometry. The maximal isometric muscle strength of the legs (m. quadriceps, Fa max, m. ischiocruralis, Fb max) was measured by computer tensiometry. Children were grouped according to their nutritional state, AEE, O2-pulse and muscle strength. When compared with normal weight children, obese and overweight children had increased fat mass (FM), fat-free mass (FFM), waist-to-hip ratio and REE, but no group differences were observed for TEE, AEE, and PAL. Obese and overweight children spent more hours per day watching TV. After correction for body weight and FFM, no group differences in REE were observed, but normal weight children had a higher O2-pulse than overweight and obese children. By contrast, RER was increased in the latter group. The fittest group had the lowest body weight, BMI, FM and FFM. Children with a low O2-pulse spent more hours per day watching TV. Grouping children according to their degree of muscle strength, younger children (4-7.5 years) did not show group differences in nutritional state, energy expenditure, physical activity and fitness. However, in the group of 7.6- to 11-year-old children, those with the greatest muscle strength and FFM had reduced BMI, skin folds, FM and FFM. FM correlated inversely with O2-pulse, but was not associated with TEE, AEE, PAL or muscle strength. By contrast TV consumption was positively associated with FM. To summarize, overweight and obese children were less fit and watched more TV than their normal weight counterparts. FM did not correspond to TEE, AEE or PAL. Muscle strength was not associated with FM in young children, but was inversely associated with FM in older children. Our cross-sectional data are consistent with the idea that increased fitness and reduced physical inactivity may prevent children from being overweight.

Body Composition↗
PubMed2001

Association between different attributes of physical activity and fat mass in untrained, endurance- and resistance-trained men.

The objective of this cross-sectional study was to assess different attributes of physical activity and fitness and their relationship to nutritional state in endurance- and resistance-trained, compared to untrained men. The subjects were 42 men matched for age, of which 13 were untrained [UT, mean age 30.2 years, mean height 180.7 cm, mean body mass 83.6 kg, mean body mass index (BMI) 25.6 kg.m-2], 14 were endurance-trained athletes (ET, mean age 29.6 years, mean height 178.4 cm, mean body mass 74.0 kg, mean BMI 23.2 kg.m-2) and 15 were resistance-trained athletes (RT, mean age 28.4 years, mean height 183.4 cm, mean body mass 94.1 kg, mean BMI 27.4 kg.m-2). Fat mass (FM), fat free mass (FFM), muscle mass (MM) and total body water (TBW) were assessed using anthropometry and bioelectrical impedance analysis. Resting energy expenditure was measured by indirect calorimetry (IC) and total energy expenditure (TEE) by a combination of IC and individually calibrated 24-h heart-rate monitoring. The activity related energy expenditure (AEE) and the physical activity level were calculated. Movements were assessed using pedometry. Aerobic fitness was determined using ergometry, muscle strength [quadriceps muscle (Famax), ischiocruralis muscle (Fbmax), biceps muscle (Fcmax), triceps muscle (Fdmax)] by computer tensiometry. Different time domain indexes of heart rate variability (HRV) were examined during sleep, rest and the whole day as an index of sympathetic nervous system (SNS) activity. When compared with UT and RT, ET had reduced body masses and FM, but increased percentage TBW (P < 0.05 and P < 0.01, respectively). FFM and MM were increased in RT, when compared with UT and ET (P < 0.01). ET had higher TEE, AEE, pedometry derived activities, oxygen consumption and power during vigorous exercise than RT and UT (P < 0.05 and P < 0.01, respectively). Respiratory exchange ratio at moderate exercise intensities was increased in RT (P < 0.05). In the 12 time domain indexes of HRV 6 and 10 were higher in ET than in RT and UT respectively (P < 0.05 or P < 0.01, respectively) suggesting an increased SNS activity in ET. By contrast, Famax, Fcmax and Fdmax were elevated in RT (P < 0.01). FM was negatively associated with aerobic fitness, but not with muscle strength. We concluded that the physiological and metabolic adaptations to exercise and nutritional state differ between ET and RT subjects. Participation in RT results predominantly in changes in body composition and strength but not in energy expenditure, movements and SNS activity. The opposite was the case for ET. Aerobic fitness, physical activity, movements and activity of SNS were all increased but body mass and FM were decreased. The latter finding may support the idea that, with regard to possible health benefits, ET is more effective than RT.

Adipose Tissue↗
PubMed1998

Heart rate deflection compared to 4 mmol x l(-1) lactate threshold during incremental exercise and to lactate during steady-state exercise on an arm-cranking ergometer in paraplegic athletes.

The deflection point (DP) of the heart rate in relation to the work rate (WR) of 8 male endurance-trained paraplegics and 11 male physically active sports students was investigated during nonsteady-state incremental arm cranking ergometry (IT) and compared to the 4 mmol x l(-1) blood lactate concentration threshold and to blood lactate concentration in steady-state exercise (SST). Heart rate, and lactate concentration from capillary blood, were determined at rest, during IT and SST. The DP was calculated by linear regression analysis of the heart rate during IT. The SST consisted of three consecutive exercise intensities over a period of 8 min at exercise intensities of 10 W below, and at 10 W above the work rate at deflection point (WRDP). No difference was found between the paraplegics and non-handicapped subjects regarding heart rate and blood lactate concentration at rest and during exercise. A DP was established in all the paraplegics and in 72.7% of the non-handicapped subjects, but lactate accumulation was observed in 75% of the paraplegics and in 62.5% of the non-handicapped subjects at the lowest intensity of SST. In summary, endurance-trained paraplegics with an injury level below T5 showed heart rate and blood lactate concentration values comparable to non-handicapped subjects during IT. A linear increase at moderate exercise intensities and a levelling-off at higher to maximal intensities could be identified in all the paraplegics and in 72.7% of non-handicapped subjects. The determination of the anaerobic threshold by DP should be applied with caution, since no causal relationship of DP and the anaerobic threshold was found and the WRDP tended to overestimate threshold values.

Adult↗
PubMed1998

Peak power and pulmonary oxygen uptake during knee extension exercise--comparisons among different incremental protocols.

Four incremental protocols of knee extension exercise of different stage durations were compared to study the effect of the protocol upon power output at the last stage (Ppeak). Previous studies of knee extension have found very different power outputs with similar ergometers and these large differences have been interpreted as being the result of the fatigue due to the durations of the protocols. The knee extension device used in previous studies was modified to avoid the action of the knee and hip flexors: the subjects pushing on a lever instead of pulling a rod. In the present study five subjects performed four incremental knee extension exercises which differed with regard to stage duration (60, 90, 180 or 360 s) on this ergometer. The Ppeak, peak oxygen uptake (VO2peak) and peak heart rate (HRpeak) were measured at the end of each of these four incremental protocols. In eight subjects, the reliability of the protocols with the two shortest increments (60 and 90-s stages) was verified by measuring Ppeak at 60 s and 90 s (Ppeak60, Ppeak90) twice. The knee ergometer proposed in the present paper was easy to use without any special training and should improve the measurement of Ppeak. The Ppeak60 [49.4 (SD 5.6) W] was higher than at 180 s [Ppeak180), 43.6 (SD 5.8) W, P < 0.05] and at 360 s [Ppeak360, 43.4 (SD 5.3) W, P < 0.05]. All the other differences in Ppeak, VO2 peak and HRpeak were not significant. All correlations between Ppeak60, Ppeak90, Ppeak180 and Ppeak360 were significant, except those between Ppeak360 and Ppeak90 or Ppeak180. The effect of the stage duration on power output and oxygen uptake at the end of the knee extension exercises was not great. Consequently, the large differences in power output and oxygen uptake observed in previous studies cannot be explained by the protocol only. The significant difference between Ppeak 60 and Ppeak90 was of the order of 10% in agreement with findings in the literature using cycle ergometry. The reliability of Ppeak60 and Ppeak90 was high and the use of these protocols can be recommended if further studies show that the measurement of Ppeak, is useful in the evaluation of local endurance.

Adult↗
PubMed1992

Predictive accuracy of criteria used to assess maximal oxygen consumption.

To evaluate criteria frequently used to designate an exercise test as maximal, 33 men and 18 women completed progressive incremental cycle ergometry to exhaustion with direct measurement of oxygen consumption (VO2). On a separate day, subjects exercised at 115% of the maximal work rate attained in the first test following a 5-minute warm-up. If VO2 exceeded that of the progressive test by greater than or equal to 150 ml/min, subjects returned on a third day and pedalled at 125% of the first day's work ratepeak. This procedure was repeated until VO2 increased less than 150 ml/min, and defined whether the progressive test was a maximal or nonmaximal test. There were 45 tests that met the criterion for maximum during the progressive test and six nonmaximal tests. Respiratory exchange ratio and 85% age-predicted maximal heart rate were sensitive criteria for a maximal test but were not specific. Attainment of age-predicted maximal heart rate and peak lactate greater than 8 mmol/L were highly specific but insensitive measures of a maximal test. In the absence of a VO2 plateau, age-predicted maximal heart rate and lactate greater than 8 mmol/L can be used as indicators of maximal tests with a high degree of confidence. When age-predicted maximal heart rate or lactate greater than 8 mmol/L are not attained, the test may still be maximal because negative predictive value is low.

Aging↗
PubMed2002

Relation of aortic distensibility determined by magnetic resonance imaging in patients > or =60 years of age to systolic heart failure and exercise capacity.

Aortic stiffness increases with advancing age and is associated with the age-related decline in exercise capacity in healthy persons. Previous studies have suggested that aortic compliance is reduced in heart failure (HF). Older persons with systolic HF can have particularly severe exercise intolerance. However, the relation between increased aortic stiffness and exercise intolerance in elderly patients with systolic HF has not been examined. Therefore, aortic distensibility of the proximal ascending aorta (assessed by magnetic resonance imaging) and exercise tolerance (assessed by maximal exercise ergometry with expired gas analysis) was measured in 28 subjects (10 healthy subjects aged 20 to 30 years, 10 healthy subjects aged > or =60 years, and 8 subjects aged > or =60 years with systolic HF). Compared with healthy older subjects, patients with systolic HF had markedly decreased distensibility of the proximal aorta (0.5 +/- 0.4 vs 2.2 +/- 1.2 10(-3) mm Hg(-1), p <0.002), decreased peak exercise volume of oxygen consumption (VO2) (858 +/- 248 vs 1,436 +/- 344 ml/min, p <0.001), and increased aortic wall thickness (3.6 +/- 0.7 vs 2.9 +/- 0.4 mm, p <0.04). Aortic distensibility was significantly correlated with peak VO2 (r = 0.80, p <0.0001) and remained so even after being adjusted for age and left ventricular (LV) ejection fraction. These data suggest that decreased aortic distensibility may contribute to exercise intolerance in older patients with HF due to LV systolic dysfunction.

Adult↗
PubMed1995

Exercise-induced hypertension in the arms due to impaired arterial reactivity after successful coarctation resection.

Exercise-induced hypertension of the arms is a well-known late complication after coarctation repair. Residual narrowing at the anastomosis site as well as abnormalities of the precoarctation arterial system may be the cause of this problem. Blood pressure response to exercise and flow-mediated arterial dilatation of the arms and legs were studied in 29 young adults after successful coarctectomy in childhood and compared with 13 control subjects. Peak exercise systolic blood pressure was significantly higher in patients than in control subjects: 238 versus 199 mm Hg (p = 0.007). Both groups had a positive systolic arm-leg gradient during exercise: 59 versus 37 mm Hg (p = 0.05). Flow-mediated dilatation of the brachial artery was significantly reduced in patients compared with that in control subjects: 4.2% (range 0% to 9.4%) versus 9.4% (range 3.7% to 16%) (p < 0.0001). Flow-mediated dilatation of the femoral artery was similar in both groups. Dilatation of the brachial artery was inversely correlated to peak exercise systolic pressure in the study patients (r = -0.427, p = 0.02). A positive arm-leg exercise gradient partly represents physiologic circulatory adaptation to ergometry and is therefore not appropriate for evaluation of residual narrowing. Exercise-induced hypertension of the arms late after coarctation repair is caused by impaired arterial reactivity, which results from structural or functional abnormality, or both.

Adolescent↗