Search PubMed⌕ Search

Biomedical subjects

A L Clark

Publications and source records attributed to A L Clark.

At least 73 records · Page 4Linked to original sources
PubMed1999

Ventilatory response to erect and supine exercise.

PURPOSE: To test the hypothesis that altering the ventilation-perfusion ratio of the lung by changing the body position from erect to supine would alter the ventilatory response to exercise as described by the slope of the relationship between minute ventilation and carbon dioxide production. METHODS: Ten normal subjects volunteers (5 female, 5 male: average age 22 yr; range 19-25 yr; height (SD) 173.5 (3.8) cm; weight 68.0 (3.3) kg) performed in random order erect and supine incremental cycle exercise with metabolic gas exchange measurements to determine peak oxygen consumption (VO2) and the slope of the relation between ventilation and carbon dioxide production (VE/VCO2 slope). RESULTS: Subjects reached a higher peak VO2 when erect (mean (SEM))(39.2 (2.4) vs 35.7 (2.0); P < 0.05). Heart rate, ventilation, and VO2 were higher at each stage in the erect position. The respiratory exchange ratio was the same in each position at matched workloads and at peak exercise. The VE/VCO2 slope was unchanged (27.8 (2.2) erect vs 27.7 (1.9) erect). CONCLUSION: Cycle exercise in the erect position is associated with an increase in exercise capacity compared with supine exercise but with no associated changes in ventilatory response to carbon dioxide production.

Adult↗
PubMed1999

Responses to constant work exercise in patients with chronic heart failure.

OBJECTIVE: To describe the kinetics of metabolic gas exchange at the onset and offset of low level, constant work exercise in patients with chronic heart failure. SETTING: Tertiary referral centre for cardiology. PATIENTS: 10 patients with chronic heart failure and 10 age matched controls. METHODS: Each subject undertook maximum incremental exercise testing with metabolic gas exchange measurements, and a fixed load exercise test at 25 watts with metabolic gas exchange measurements before, during, and after the test. A monoexponential curve was fitted to the data to describe the kinetics of gas exchange at onset and offset of fixed load exercise. OUTCOME MEASURES: Peak oxygen consumption; time constants of onset and offset for metabolic gas exchange variables during constant load exercise. RESULTS: Peak oxygen consumption (mean (SD)) was higher in controls (26.1 (4.3) v 15.3 (5.3) ml/kg/min; p < 0.001) than in heart failure patients. Oxygen consumption during steady state was the same in both groups (9.2 (1.8) ml/kg/min in controls v 8.6 (1.6) in patients). The time constant of onset was the same in each group, but the time constant of offset was longer in patients (1.29 (0.14) v 0.82 (0.07); p < 0.005). There was a relation between peak oxygen consumption and time constant of offset (R = 0.56; p < 0.001). CONCLUSIONS: The dynamics of gas exchange at the onset of low level exercise are normal in heart failure, but the recovery is delayed. The delay is related to the reduction in exercise capacity. A patient may spend a greater portion of the day recovering from exercise, and may not begin the next bout from a position of true recovery, perhaps contributing to the sensation of fatigue.

Aged↗
PubMed1998

Atypical case of Smith-Lemli-Opitz syndrome: implications for diagnosis.

Smith-Lemli-Opitz (SLO) syndrome is an autosomal recessive disorder comprised of recognizable facial abnormalities, growth retardation, and multiple congenital anomalies, commonly involving genitalia, second and third toe syndactyly, and cleft palate. The condition is associated with hypocholesterolemia and elevated levels of 7-dehydrocholesterol (7DHC) resulting from deficient activity of the enzyme 7-dehydrocholesterol reductase. The clinical spectrum of SLO ranges from individuals with mental retardation and minor anomalies to those with major structural defects and early or even prenatal lethality. Low maternal serum unconjugated estriol (uE3) levels and a variety of fetal ultrasound anomalies have been identified in affected pregnancies, and prenatal diagnosis is possible by measurement of amniotic fluid 7DHC levels in pregnancies known to be at risk because of a previously affected child. We report on a pregnancy with low maternal uE3 level, abnormal antenatal ultrasound findings including limb deformities, ventriculomegaly, and hydrops fetalis, and a normal 46,XY karyotype. The infant died at birth. At autopsy the infant had hydrops, unusual face, cleft palate, genital abnormalities, Dandy-Walker malformation, and absence of toe syndactyly. Tests performed on cultured skin fibroblasts showed elevated levels of 7DHC and abnormalities of cholesterol biosynthesis characteristic of the metabolic defect that causes SLO. The atypical findings of hydrops, uncharacteristic facial appearance, and absence of toe syndactyly in this case additionally illustrates the wide phenotypic spectrum of SLO and the need for a high index of suspicion for a disorder with great clinical variability. Identification of another affected pregnancy with a low maternal uE3 level and abnormal fetal ultrasound findings in the presence of a normal karyotype lends additional support for consideration of prenatal biochemical testing for SLO in pregnancies with these findings, including pregnancies not previously known to be at risk.

Adult↗
PubMed1998

Effects of exercise position on the ventilatory responses to exercise in chronic heart failure.

OBJECTIVE: Patients with heart failure frequently complain of orthopnoea. The objective was to assess the ventilatory response of patients with chronic heart failure during erect and supine exercise. DESIGN: Maximal incremental exercise testing with metabolic gas exchange measurements in erect and supine positions conducted in random order. SETTING: Tertiary referral centre for cardiology. PATIENTS: Nine patients with heart failure (aged 61.9+/-6.1 years) and 10 age matched controls (63.8+/-4.6). OUTCOME MEASURES: Metabolic gas exchange measurements. The slope of the relation between ventilation and carbon dioxide production. Ratings of perceived breathlessness during exercise. RESULTS: Oxygen consumption (VO2) and ventilation were higher during erect exercise at each stage in each group. Peak VO2 was [mean (SD)] 17.12 ml/kg/min (4.07) erect vs 12.92 (3.61) supine in the patients (P<0.01) and 22.62 (5.03) erect-supine vs 19.16 (3.78) erect (P<0.01) in the controls. Ratings of perceived exertion were higher in the patients at each stage, but unaffected by posture. There was no difference in the slope of the relation between ventilation and carbon dioxide production between erect and supine exercise 36.39 (6.12) erect vs 38.42 (8.89) supine for patients; 30.05 (4.52) vs 28.80 (3.96) for controls. CONCLUSIONS: In this group of patients during exercise, there was no change in the perception of breathlessness, nor the ventilatory response to carbon dioxide production with change in posture, although peak ventilation was greater in the erect position. The sensation of breathlessness may be related to the appropriateness of the ventilatory response to exertion rather than to the absolute ventilation.

Chronic Disease↗
PubMed1998

Hemolytic disease of the fetus: a comparison of the Queenan and extended Liley methods.

OBJECTIVE: To compare the clinical utility of the Liley and Queenan methods to monitor the severity of fetal hemolytic disease. METHODS: Amniotic fluid bilirubin was measured in specimens from 73 women sensitized to red blood cell antigens. Chloroform-extracted amniotic fluid was evaluated spectrophotometrically for bilirubin content by using the change-from-expected value of the optical density at 450 nm. Values in the four Queenan zones were compared with those of the four zones of the Liley graph (middle zone subdivided). Clinical utility and accuracy of the two methods were compared. RESULTS: Treatment was based on interpretation of bilirubin values plotted on the Liley graph. Hydrops fetalis was not observed. The highest value for each patient was significantly more likely to be plotted in the highest zone using the Queenan method (23 of 73 compared with eight of 73 patients; P < .001). Overestimation of risk occurred with greater frequency when using the Queenan method (13 of 67 compared with seven of 67 patients; P = .031). Overestimation of risk by the Queenan method also was more likely at or before 28 weeks' gestation (10 of 49 compared with four of 49 patients; P = .031). In nine cases (13%), the Queenan graph and method would have prompted unnecessary or premature umbilical vein sampling that was withheld using the Liley graph. CONCLUSION: The performance of the linearly extended Liley graph was superior to that of the Queenan graph, because the Queenan method frequently overestimated risk.

Amniotic Fluid↗
PubMed1998

Deficient insulin-like growth factor I in chronic heart failure predicts altered body composition, anabolic deficiency, cytokine and neurohormonal activation.

BACKGROUND: Recent studies of growth hormone supplementation in chronic heart failure have been associated with variable results. Acquired abnormalities of biochemical parameters of the growth hormone insulin-like growth factor I axis have been associated with severe chronic heart failure. There are suggestions of an acquired growth hormone resistance with deficient insulin-like growth factor I in some patients. OBJECTIVES: Therefore, we set out to investigate the clinical and functional status and the degree of cytokine and neurohormonal alteration of chronic heart failure patients with deficient insulin-like growth factor I responses. METHODS: Patients with chronic heart failure were divided into two groups according to their insulin-like growth factor I levels (classified according to the manufacturer's assay range in normal controls): low insulin-like growth factor I <104 (n = 20; 89 +/- 9.6 ng/ml), and normal/high >104 ng/ml (n = 32; 169 +/- 52 ng/ml). Between groups there was no difference in age (low versus high: 65.3 +/- 12.1 versus 61.6 +/- 9.1 years, p = 0.21), body mass index, aerobic capacity (peak oxygen consumption: low versus high: 15.5 +/- 5.2 versus 17.3 +/- 6.3 mL/kg/min, p = 0.23), left ventricular ejection fraction, New York Heart Association classification. RESULTS: During quadriceps strength testing, patients with low insulin-like growth factor I had reduced absolute strength (-24%), and strength per unit area muscle (- 14%) than patients with normal/high insulin-like growth factor I. Leg muscle cross-sectional area was lower in the low insulin-like growth factor I group (-12% and -13% for right and left legs, respectively). These alterations were accompanied by increased levels of growth hormone (+145%), tumor necrosis factor-alpha (+46%), cortisol/ dehydroepiandrosterone ratio (+60%), noradrenaline (+49%) and adrenaline (+136%) (all at least p < 0.05). CONCLUSIONS: Patients with low insulin-like growth factor I levels show signs of altered body composition, cytokine and neuroendocrine activation, to a greater extent than patients with normal/high levels.

Adrenergic alpha-Agonists↗
PubMed1998

Predictive value of fetal ultrasonography in the diagnosis of a lethal skeletal dysplasia.

BACKGROUND: Certain ultrasonographic findings identified in a fetus suspected of having a skeletal dysplasia may be predictive of a lethal outcome. METHODS: We evaluated 27 fetuses suspected of having a skeletal dysplasia using targeted ultrasonography between 16 and 31 weeks' gestation. Clinical examination and skeletal radiography were done after delivery. RESULTS: A skeletal dysplasia was confirmed and a diagnosis established in all but one case. The skeletal dysplasia was lethal in 23 cases and, in each case, the outcome was accurately predicted prenatally; however, three of the infants survived several months. In 11 of the 23 cases (48%), the specific diagnosis was correctly determined before birth. Ultrasonographic findings not considered to reflect a lethal outcome, were accurately predicted in two other cases. In an additional two, sonographic examination suggested a lethal osteochondrodysplasia, though both survived. Findings consistent with a lethal skeletal dysplasia included a femur length < 1st centile, combined with either a bell-shaped thorax, decreased bone echogenicity, or both. Using these criteria provided a positive-predictive value for neonatal deaths of 80% (20/25), and 92% (23/25) if the three that died in infancy were included. CONCLUSIONS: In the fetus suspected of having a skeletal dysplasia, certain findings on targeted ultrasonography frequently are predictive of a lethal outcome; the ability to predict this appears greatest when more than one of these abnormalities is present.

Bone and Bones↗
PubMed1997

Wasting as independent risk factor for mortality in chronic heart failure.

BACKGROUND: Wasting in chronic heart failure (CHF) has long been known but is little investigated. We sought to find out whether the cachectic state in CHF provides additional prognostic information about all-cause mortality. METHODS: Between June, 1993, and May, 1995, we studied 171 consecutive patients with CHF (mean age 60 years [SD 11; range 27-86]; 17 female). We assessed exercise capacity (peak oxygen consumption; mean 17.5 mL kg-1 min-1 [6.7]), functional status (New York Heart Association [NYHA] class: 21 class I, 63 class II, 68 class III, 19 class IV), and left-ventricular ejection fraction (mean 30% [SD 15]; n = 115). The cachectic status was defined prospectively as a non-intentional documented weight loss of at least 7.5% of previous normal weight (28 patients; range 9-36% or 6-30 kg) during at least 6 months. The Cox proportional-hazards model was used to assess the association of variables with survival, and Kaplan-Meier cumulative survival plots were constructed to estimate the influence of risk factors. FINDINGS: At the end of follow-up in November, 1996, 49 patients had died (after a mean 324 days [SD 283]). The mean follow-up of the survivors was 834 days (SD 186; range 549-1269). The cachectic state was predictive of 18-month mortality independent of age, NYHA class, left-ventricular ejection fraction, and peak oxygen consumption. Mortality in the cachectic patients (n = 28) was 18% at 3 months, 29% at 6 months, 39% at 12 months, and 50% at 18 months. Patients who had a peak oxygen consumption below 14 mL kg-1 min-1 (n = 53) had mortality at 3, 6, 12, and 18 months of 19%, 30%, 40%, and 51%. 18-month survival was 23% (95% CI 0-46) for the 13 patients with both of these risk factors (cachexia and low peak oxygen consumption) compared with 93% (88-98) in those (n = 103) with neither risk factor (p < 0.0001). INTERPRETATION: The cachectic state is a strong independent risk factor for mortality in patients with CHF. Combined with a low peak oxygen consumption, it identifies a subset of patients at extremely high risk of death. Assessment of cachexia should be included in transplant programmes and studies that investigate the effect of interventions by survival analyses.

Adult↗
PubMed1997

Blind atrial pacing for patients with sinus node disease who develop atrial fibrillation during permanent pacemaker implantation.

During a 6-year period, six of 110 patients implanted with AAI pacemakers for sick sinus syndrome developed atrial fibrillation at the time of pacemaker implantation (5.5%). In all cases a passive fixation lead was sited in the right atrial appendage, its stability being ensured by rotation of the lead and phrenic nerve stimulation excluded by pacing at 10 V. One patient remained in chronic atrial fibrillation. In the other five, who subsequently reverted to sinus rhythm, atrial P-wave sensing and lead threshold values were satisfactory, allowing programming of the pacemaker output down to 2.5 V to conserve the battery. One out of these five patients continued to have intermittent atrial fibrillation. We conclude that in sick sinus syndrome, atrial fibrillation complicates AAI pacemaker implantation procedure in 5.5% of cases. As an alternative to an unplanned general anaesthetic to cardiovert the patient, it is reasonable to implant an atrial lead in the right atrial appendage in the expectation of a spontaneous reversion to sinus rhythm with a good lead threshold and P-wave sensing. In contrast to inappropriate pacing of the right ventricle in VVI mode, this strategy avoids pacemaker syndrome and reduces the risk of subsequent attacks of atrial fibrillation.

Atrial Fibrillation↗
PubMed1997

Clinical uses of intravenous immunoglobulin in pregnancy.

Intravenous immunoglobulin was licensed for use in the United States in 1981. Currently, there are only a few Food and Drug Administration-labeled indications for intravenous immunoglobulin, but up to 50 "off-label" uses are reported in the literature. The obstetric literature contains numerous reports on intravenous immunoglobulin therapy during pregnancy. This article reviews the properties, pharmacokinetics, mechanisms of action, and side effects of intravenous immunoglobulin, as well as the reported uses of intravenous immunoglobulin during pregnancy.

Antiphospholipid Syndrome↗
PubMed1997

Epidemiology of surgically managed pelvic organ prolapse and urinary incontinence.

OBJECTIVE: To determine the incidence of surgically managed pelvic organ prolapse and urinary incontinence in a population-based cohort, and to describe their clinical characteristics. METHODS: Our retrospective cohort study included all patients undergoing surgical treatment for prolapse and incontinence during 1995; all were members of Kaiser Permanente Northwest, which included 149,554 women age 20 or older. A standardized data-collection form was used to review all inpatient and outpatient charts of the 395 women identified. Variables examined included age, ethnicity, height, weight, vaginal parity, smoking history, medical history, and surgical history, including the preoperative evaluation, procedure performed, and details of all prior procedures. Analysis included calculation of age-specific and cumulative incidences and determination of the number of primary operations compared with repeat operations performed for prolapse or incontinence. RESULTS: The age-specific incidence increased with advancing age. The lifetime risk of undergoing a single operation for prolapse or incontinence by age 80 was 11.1%. Most patients were older, postmenopausal, parous, and overweight. Nearly half were current or former smokers and one-fifth had chronic lung disease. Reoperation was common (29.2% of cases), and the time intervals between repeat procedures decreased with each successive repair. CONCLUSION: Pelvic floor dysfunction is a major health issue for older women, as shown by the 11.1% lifetime risk of undergoing a single operation for pelvic organ prolapse and urinary incontinence, as well as the large proportion of reoperations. Our results warrant further epidemiologic research in order to determine the etiology, natural history, and long-term treatment outcomes of these conditions.

Adult↗
PubMed1997

Clinical correlates and prognostic significance of the ventilatory response to exercise in chronic heart failure.

OBJECTIVES: This study sought to investigate the clinical characteristics of patients with chronic heart failure and an increased ventilatory response to exercise and to examine the prognostic usefulness of this response. BACKGROUND: The ventilatory response to exercise is increased in many patients with chronic heart failure and may be characterized by the regression slope relating minute ventilation to carbon dioxide output (VE-VCO2 slope) during exercise. METHODS: One hundred seventy-three consecutive patients (155 men; mean [+/-SD] age 59.8 +/- 11.5 years; radionuclide left ventricular ejection fraction [LVEF] 28.4 +/- 14.6%) underwent cardiopulmonary exercise testing (peak oxygen consumption 18.5 +/- 7.3 ml/kg per min; VE-CO2 slope 34.8 +/- 10.6) over a 2-year period. Using 1.96 standard deviations above the mean VE-VCO2 slope of 68 healthy age-matched subjects (mean slope 26.3 +/- 4.1), we defined a high ventilatory response to exercise as a slope >34. RESULTS: Eighty-three patients (48%) had an increased VE-VCO2 slope (mean 43.1 +/- 8.9). There was a difference in age (62.2 vs. 57.3 years, p = 0.005), New York Heart Association functional class (2.9 vs. 2.1, p < 0.001), LVEF (24.7 vs. 31.9%, p = 0.0016), peak oxygen consumption (14.9 vs. 21.7 ml/kg per min, p < 0.0001) and radiographic cardiothoracic ratio (0.58 vs. 0.55, p = 0.002) between these patients and those with a normal slope. In the univariate Cox proportional hazards model, the E-VCO2 slope was an important prognostic factor (p < 0.0001). In the multivariate Cox analyses using several variables (age, peak oxygen consumption, VE-VCO2 slope and LVEF), the VE-VCO2 slope gave additional prognostic information (p = 0.018) beyond peak oxygen consumption (p = 0.022). Kaplan-Meier survival curves at 18 months demonstrated a survival rate of 95% in patients with a normal VE-VCO2 slope compared with 69% in those with a high slope (p < 0.0001). CONCLUSIONS: A high VE-VCO2 slope selects patients with more severe heart failure and is an independent prognostic marker. The VE-VCO2 slope may be used as a supplementary index in the assessment of patients with chronic heart failure.

Aged↗
PubMed1997

Insulin resistance in chronic heart failure: relation to severity and etiology of heart failure.

OBJECTIVES: We attempted to assess insulin sensitivity in patients with chronic heart failure (CHF) and its relation to disease severity. BACKGROUND: Peripheral muscular changes influence the progression of heart failure. This effect may be due to chronic disturbances of insulin and glucose metabolism that affect the energy status of skeletal and myocardial muscle. METHODS: We investigated insulin sensitivity in 79 men-38 patients with CHF, 21 patients with angiographic evidence of coronary artery disease without CHF and 20 healthy control subjects-and assessed its relation to disease severity, etiology and hormonal status (all subjects had a similar age and body mass index). Insulin sensitivity was estimated by minimal modeling analysis of the glucose and insulin and profiles during a 0.5 g/kg body weight intravenous glucose tolerance test. RESULTS: Compared with control subjects, patients with CHF had similar mean fasting glucose but increased insulin levels (67 vs. 29 pmol/liter, p < 0.002) and a 58% reduced mean insulin sensitivity (2.01 vs. 4.84 min-1/pmol/ml x 10(5), p < 0.0001). Peak oxygen consumption (VO2) (r = 0.63), fasting triglycerides (r = -0.62) and age (r = -0.46, all p < 0.001) predicted insulin sensitivity independently. Rest norepinephrine and epinephrine levels, left ventricular ejection fraction and heart failure etiology were not related to insulin sensitivity. Patients with coronary artery disease but no CHF had an intermediate mean insulin sensitivity (3.30 min-1/pmol/ml x 10(5) [-32%, p = 0.042 vs. control subjects; +113%, p = 0.0023 vs. patients with CHF due to ischemic heart disease]). In multivariate analyses of all 79 subjects, age (p = 0.0006), triglycerides (p = 0.0023), fasting insulin (p = 0.0037) and the presence of CHF (p = 0.018) were independent predictors of impaired insulin sensitivity (adjusted joint R2 = 0.53, p < 0.0001). CONCLUSIONS: CHF is associated with marked insulin resistance, characterized by both fasting and stimulated hyperinsulinemia. Advanced heart failure (in terms of reduced peak VO2) is related to increased insulin resistance, but this is not directly mediated through ventricular dysfunction or increased catecholamine levels.

Blood Glucose↗
PubMed1997

Tumor necrosis factor and steroid metabolism in chronic heart failure: possible relation to muscle wasting.

OBJECTIVES: We sought to assess the possible relations between clinical severity of chronic heart failure and catabolic factors, specifically tumor necrosis factor (TNF), soluble TNF receptors 1 and 2 (sTNFR-1 and sTNFR-2), cortisol, testosterone and dehydroepiandrosterone (DHEA). BACKGROUND: Chronic heart failure is associated with loss of muscle bulk that may be related to alteration of the balance between catabolism and anabolism. METHODS: Sixty-three patients (average age +/- SD 60.4 +/- 11.3 years) with stable chronic heart failure and 20 control subjects aged 52.8 +/- 11.4 years were studied. We measured body mass index (BMI) and obtained maximal incremental exercise testing with metabolic gas exchange measurements and measurements of venous levels of TNF, sTNFR-1 and sTNFR-2, cortisol and DHEA. RESULTS: There was no difference in total TNF-alpha levels between patients and control subjects (9.76 +/- 8.59 vs. 6.84 +/- 2.7 pg/ml). sTNFR-1 (128.9 +/- 84.5 vs. 63.6 +/- 23.3 pg/ml, p < 0.003) and sTNFR-2 (250.1 +/- 109.5 vs. 187.9 +/- 92.2 pg/ml, p = 0.03) were higher in patients. DHEA was lower in patients (9.88 +/- 6.94 vs. 15.64 +/- 8.33 nmol/liter, p = 0.004). The ratio of log cortisol to log DHEA correlated with log TNF level (r = 0.50, p < 0.001 for the patients alone; r = 0.48, p < 0.001 for the group as a whole). Peak oxygen consumption correlated with both sTNFR-1 and sTNFR-2 (r = -0.51, p < 0.001 and r = -0.39, p < 0.001, respectively). There was a negative correlation between BMI and TNF levels (r = -0.43, p < 0.001 for the patients) and the cortisol/DHEA ratio (r = -0.32, p = 0.01 for the patients). CONCLUSIONS: There is an increase in TNF and its soluble receptors in chronic heart failure. This increase is associated with a rise in the cortisol/DHEA (catabolic/anabolic) ratio. These changes correlate with BMI and clinical severity of heart failure, suggesting a possible etiologic link.

Aged↗
PubMed1997

Exercise dynamics at submaximal workloads in patients with chronic heart failure.

BACKGROUND: The aims of this study were to analyze the relationship between exercise at self-selected work loads and peak exercise performance in patients with chronic heart failure and to analyze possible relationships between gait pattern and exercise performance and ventilatory response to exercise in chronic heart failure. METHODS AND RESULTS: Twelve patients with stable chronic heart failure and 10 age- and build-matched control subjects undertook symptom-limited maximal exercise testing with metabolic gas exchange measurements to determine peak oxygen consumption (VO2) and the slope of the relationship between ventilation and carbon dioxide production (VE/VCO2 slope). Respiratory rate was also determined. Self-selected walking pace and cadence (steps per minute) were determined. Metabolic gas exchange analysis was repeated at matched low-level exercise and at self-selected walking pace. Self-selected exercise was at a lower speed for patients than control subjects (1.28 [0.22] vs 1.43 [0.19] m s-1), representing a similar proportion of peak oxygen consumption (63.6 [19.3]% vs 56.7 [25.4]%). There was a relationship between peak VO2 and VO2 at self-selected workload (r = .55, P < .001) and self-selected walking velocity (r = .58, P < .005). Gait analysis demonstrated that the reduction in self-selected velocity in heart failure patients was due to a reduced cadence (101.5 [8.7] steps/min vs 110.2 [9.1] steps/min, P < .01), not a reduction in stride length. There was a negative relationship between VE/VCO2 slope and self-selected cadence (r = -.68, P < .001) and a negative correlation between respiratory rate and cadence at self-selected workload (r = -.6, P < .005). CONCLUSIONS: Self-selected walking speed is at the same proportion of peak oxygen consumption in patients with heart failure as compared with control subjects, but a lower absolute level. Patients have the same stride length as normal control subjects. Ventilation is increased in patients, but there is no direct relationship between ventilation and gait.

Exercise Test↗