Standardized Treadmill Test Research Articles

Effects on exercise response, fluid and acid‐base balance of protein intake from forage‐only diets in Standardbred horses

High-energy forage might be an alternative to concentrates for performance horses and such forage can be produced by an early cut. However, early cut forage is high in crude protein (CP), which may result in an excessive CP intake. To investigate how CP intake affects nitrogen (N), fluid and acid-base balance, and exercise response in horses fed high-energy forage diets. The hypothesis was that high CP intake causes acidosis, and alters fluid balance and response to intensive exercise. Two forage-only diets based on high-energy grass forage were fed for 23 days in a crossover design to 6 Standardbred horses in racing condition. One forage diet provided a high (HP) CP (16.6%) intake and the other diet provided recommended intake (RP) of CP (12.5%) for racehorses. The horses had intensive exercise twice and slow exercise 1-3 times every week. At the beginning and end of each period, faeces and urine were collected for 48 and 72 h, respectively and analysed for dry matter, pH and N content. At Days 19 and 23 in each period 2 race-like exercise tests were performed, a standardised treadmill test and a field test on a race track. Blood samples were taken before, during and after the tests and analysed for sodium (Na), potassium (K), chloride (CI), total plasma proteins (TPP), TCO2, urea, pH and lactate. The strong ion difference (SID) was calculated and heart rate and respiratory rate was also recorded. There was a decrease in urinary pH and an increase in N excretion, blood urea, water intake, urine volume and faecal water content on the HP diet. Total water intake was higher than the increase in urinary and faecal water loss indicating increased evaporative losses on the HP diet. During the exercise tests there were no significant differences between diets in TPP, plasma lactate, blood Na, K, Cl, TCO2, pH, SID and respiratory or heart rates. Feeding a forage-only diet with a CP intake corresponding to 160% of the requirement caused an increase in N excretion within 36-48 h after the diet was introduced and alterations in fluid and acid base balance at rest. The increased urine and probably also evaporative fluid losses suggest that feeding a HP diet will cause an unnecessary challenge for horses during prolonged exercise.

The PADHOC Device is a Better Guide to the Actual Incapacity Suffered by Claudicants than the Gold Standard Constant Load Treadmill Test

The Constant Load Treadmill Test (CLTT) is currently the primary method used to measure walking impairment in patients with peripheral vascular disease. The aim of this study was to compare the CLTT and PADHOC device as assessments of walking impairment. 55 patients with intermittent claudication underwent a CLTT and a Double Physiological Walking Test (DPWT) using the PADHOC device. Health-related quality of life was measured using the Short Form 36 and the Claudication Scale. The initial claudication and maximum walking distance from the first part of the DPWT showed the best correlation with domains of pain and physical function. The DPWT is more representative of the functional incapacity experienced by patients with intermittent claudication. We believe that the PADHOC is a suitable alternative to the CLTT in the assessment of this patient group.

Brief Communication: Ramipril Markedly Improves Walking Ability in Patients with Peripheral Arterial Disease

Peripheral arterial disease (PAD) affects up to 12% of adults older than 50 years of age. Conventional therapies have only modest effects in improving symptoms. To examine the effects of angiotensin-converting enzyme inhibition on walking ability in patients with PAD. Randomized, double-blind, placebo-controlled trial initiated in March 2003 and completed in January 2005. The Alfred Hospital, Melbourne, Australia. 40 older adults with symptomatic PAD and no history of diabetes or hypertension. 10 mg of ramipril (n = 20) or placebo (n = 20) once daily for 24 weeks. All patients completed the trial. Pain-free and maximum walking time were recorded during a standard treadmill test, and the standard Walking Impairment Questionnaire was administered. After adjustment for the baseline pain-free walking time, mean pain-free walking time after ramipril treatment was 227 seconds (95% CI, 175 seconds to 278 seconds; P < 0.001) longer than that after placebo treatment. Similarly, maximum walking time improved by 451 seconds in the ramipril group (CI, 367 seconds to 536 seconds; P < 0.001) but did not change in the placebo group. Ramipril improved the Walking Impairment Questionnaire median distance score from 5% (range, 1% to 39%) to 21% (range, 12% to 58%; P < 0.001), speed score from 3% (range, 3% to 39%) to 18% (range, 8% to 50%; P < 0.001), and stair-climbing score from 17% (range, 4% to 80%) to 67% (range, 38% to 88%; P < 0.001). No adverse events were reported. The sample size is modest, and the strict inclusion criteria limit the applicability of the results to patients with claudication and infrainguinal disease and those without diabetes. Ramipril improved pain-free and maximum walking time in some adults with symptomatic PAD.

Cardiorespiratory Strain During Inclined Treadmill Walking in a Hot-Dry Environment Whilst Wearing Weighted-Clothing

The nature and scale of equipment that must be carried by emergency and security services during operations together with the need to afford personal protection from potential hazards adds weight to the body. Added weight risks increasing the metabolic demand (MD) thereby limiting the time that can be sustained on duty. Whilst strategies to mitigate MD tend to reduce the mass of equipment and clothing there is a need to understand the effect of the distribution of the load on the body. During walking gait Knapik et al 2004 reported that the rise in oxygen cost for a given mass was lowest when loads were placed closest to the body's centre of mass (CoM). However, tight-fitting loads around the chest were found to restrict breathing and increase heat strain by comparison with carrying the load on the back. PURPOSE: To compare the cardiorespiratory strain (CrS) of a standard treadmill task for 4 garments where increased load was maintained close to the CoM. METHODS: Seven healthy, heat-acclimatised, male volunteers (mean (1 sd) age 21.3 (3.5) years; body mass (BM) 76.0 (8.8) kg; height 1.79 (0.08) m) participated in this ethics approved study. Participants (PPs) conducted a standard motor-driven treadmill test (TT) (walking for 120 min (speed: 5.3 km.h−1; incline: 4.0%) in a climate-controlled laboratory (CL) (38.0°C dry-bulb temperature, 30% relative humidity) while fluids were consumed ad libitum) on 4 consecutive days. PPs wore Standard Operational Clothing (SOC: underwear, British Army combat clothing, socks, boots and webbing) weighing 10.1 (0.2) kg. One of 4 (A to D) garments (A: 5.2 kg; B: 9.2 kg; C: 8.6 kg; D: 7.9 kg) was fitted to the torso of PPs prior to each TT. Garments were matched for moisture vapour permeability. Loads within each garment were evenly distributed. The order in which PPs wore each garment was randomised. Douglas bags were used to assess VO2 and VE within the CL prior to- and at 30 min intervals throughout TT. Aural temperature (Tau) was monitored to ensure the safety of PPs. Statistical evaluation was by paired T-test with α = 0.05. RESULTS: Despite Tau remaining within safe limits only 4 PPs completed 120 min of TT, 6 completed 90 min whilst all 7 completed 60 min. Differences in VO2 (mean (1sd) ml.min−1.kg(BM)−1: A 25.2 (1.9); B 26.3 (2.4); C 28.9 (4.8): D 24.8 (3.6)) and VE ((L. min−1) A 42.5 (6.6); B 44.7 (9.2); C 45.8 (14.1); D 40.9 (7.3)) between garments were not statistically significant (p>0.05). CONCLUSIONS: Although the small sample size cannot substantiate generalisations of the results these data suggest that strategies to mitigate CrS of carrying loads on the body must consider how the load is distributed.

Exercise Single-Photon Emission Computed Tomography Provides Effective Risk Stratification of Elderly Men and Elderly Women

In a recent study, we reported that the Duke treadmill score was unable to effectively stratify elderly patients according to risk. The purpose of this study was to evaluate the prognostic value of exercise single-photon emission computed tomography (SPECT) in this same population and to examine results by gender. A cohort of 247 elderly (age > or =75 years) patients (108 women, 139 men, age 77+/-3 years) who underwent exercise thallium-201 SPECT were followed up for a median duration of 6.4 years. SPECT variables were significantly associated with cardiac death: summed stress score (SSS) chi2=19.5, P<0.001; summed difference score chi2=12.3, P<0.001; increased lung uptake chi2=9.6, P=0.002; and left ventricular enlargement chi2=8.3, P=0.004. The Duke score was not significantly associated with cardiac death (chi2<1, P=NS). The SSS classified most patients as low risk (49%) or high risk (35%); the Duke score classified the majority (68%) as intermediate risk. Annual cardiac mortality rates for patients categorized by SSS as low risk and high risk were 0.8% and 5.8%, respectively. Cardiac survival rates according to SSS risk categories were significantly different for both women (P=0.012) and men (P=0.003). SPECT classified most elderly patients into clinically useful low- and high-risk categories and accurately predicted outcomes in both genders. If these results can be validated in future studies, exercise SPECT rather than standard treadmill testing may emerge as the initial noninvasive testing strategy in elderly patients who are able to exercise.

Effect of Airway Disease on Blood Gas Exchange in Racehorses

Inflammatory Airway Disease (IAD), exercise-induced pulmonary hemorrhage (EIPH), and upper airway obstruction (UAO) are common respiratory tract diseases that can decrease performance. The purpose of this retrospective study was to compare bronchoalveolar lavage fluid cytology and arterial blood gas analysis during a treadmill test by poorly performing racehorses presented to Purdue University. One hundred thirty-two horses with a history of poor performance were included in this study. Ten horses with no history or diagnosis of EIPH, IAD, or UAO served as controls. Horses were evaluated by rhinolaryngoscopy for upper airway abnormalities and underwent a standardized treadmill test, and samples were collected for blood gas analysis. Horses with IAD or EIPH had a more severe exercise-induced hypoxemia, (mean+/-SD; 84.8+/-1.5 and 86.0+/-1.7 mm Hg average Pao2, respectively), than horses in the control group (92.8+/-2.1 mm Hg). The average Pao2 of horses with only UAO (88.3+/-3.3 mm Hg) was not significantly different from control horses. Gas exchanges were the most severely impaired in horses affected with both EIPH and UAO because they exhibited the lowest Pao2 and highest Paco2 values (66.5+/-15.2 and 52.2+/-6.3 mm Hg, respectively).

Treadmill versus Shuttle Walk Tests of Walking Ability in Intermittent Claudication

To compare treadmill and shuttle walk tests for assessing functional capacity in patients with intermittent claudication, with respect to test-retest reliability, cardiovascular responses, and patient preferences. Patients with stable intermittent claudication (N = 55, ages 52-85 yr, median age 68 yr) were recruited from the Sheffield Vascular Institute at the Northern General Hospital, Sheffield, UK. Each patient performed an incremental shuttle walk test, a constant-pace shuttle walk test, and a standardized treadmill test (3.2 km x h(-1), 12% gradient), each on three occasions. The incremental shuttle walk began at 3 km x h(-1) and increased by 0.5 km x h(-1) every minute, whereas the constant-pace shuttle walk was performed at the fixed pace of 4 km x h(-1). Claudication distance (CD), maximum walking distance (MWD), heart rate (HR), and blood pressure were assessed in each testing session. The patients also completed a test preference questionnaire. CD and MWD for both shuttle walks were greater than the corresponding walking distances achieved in the treadmill test (P < 0.001). Average coefficients of variation for repeated incremental shuttle walk, constant-pace shuttle walk, and treadmill tests were 15.9%, 21.1%, and 18.7%, respectively, for MWD, corresponding to average intraclass correlation coefficients of 0.87, 0.82, and 0.87. Treadmill walking evoked greater increases in HR and blood pressure (P < 0.001), and fewer patients expressed a preference for it (24 vs 43% for shuttle walking). These findings indicated that shuttle walk testing exhibits similar test-retest reliability as treadmill testing, but that it evoked a lower level of cardiovascular stress and is preferred to treadmill testing by a large proportion of patients.

Chronic Transcutaneous Electrical Stimulation of Calf Muscles Improves Functional Capacity without Inducing Systemic Inflammation in Claudicants

Objectives. To assess whether electrical stimulation of ischaemic calf muscles in claudicants causes a systemic inflammatory response and to evaluate effects of its chronic application on muscle function and walking ability.Design. Prospective randomised controlled trial of calf muscle stimulation.Materials and methods. Stable claudicants were randomised to receive either active chronic low frequency (6 Hz) motor stimulation (n=15) or, as a control treatment, submotor transcutaneous electrical nerve (TENS) stimulation (n=15) of calf muscles in one leg, 3×20 min per day for four weeks. Leucocyte activation was quantified by changes in cell morphology, vascular permeability by urinary albumin:creatinine ratio (ACR), calf muscle function by isometric twitch contractions and walking ability by treadmill performance pre- and post-intervention.Results. Acute active muscle stimulation activated leucocytes less (28% increase) than a standard treadmill test (81% increase) and did not increase ACR. Chronic calf muscle stimulation significantly increased pain-free walking distance by 35 m (95% CI 17, 52, P<0.001) and maximum walking distance by 39 m (95% CI 7, 70, P<0.05) while control treatment had no effect. Active stimulation prevented fatigue of calf muscles during isometric electrically evoked contractions by abolishing the slowing of relaxation that was responsible for loss of force.Conclusions. Chronic electrical muscle stimulation is an effective treatment for alleviating intermittent claudication which, by targeted activation of a small muscle mass, does not engender a significant systemic inflammatory response.

Effects of sildenafil citrate (Viagra) on hemodynamic parameters during exercise testing and occurrence of ventricular arrhythmias in patients with erectile dysfunction and cardiovascular disease.

Erectile dysfunction (ED) is frequently observed in male cardiovascular disease (CVD) patients, creating concern about cardiac risk of their sexual activity, and their therapeutic use of sildenafil. Relatively little information exists about sildenafil effects on exercise testing, hemodynamic parameters or on occurrence of ventricular arrhythmias during normal activities in CVD patients. Single, oral doses of sildenafil do not significantly affect exercise-induced changes in hemodynamic parameters or occurrence of arrhythmias in ED/CVD patients. ED patients, with or without CVD, were enrolled in one of two studies. In the first, patients underwent standard (Bruce Protocol) treadmill tests; an initial control test was followed 1 hour later by administration of 100mg oral sildenafil. After another hour, they underwent a second treadmill test. Systolic and diastolic blood pressure (SBP and DBP), heart rate, and double product were determined for each evaluation at pretest, maximum stress, and recovery. In the second, Holter ambulatory ECGs were recorded 5 hours before and 6 hours after 100mg oral sildenafil administration. Sildenafil had no clinically significant effects on exercise-induced changes in hemodynamic parameters in cardiac patients and only slight, clinically insignificant effects in noncardiac patients. ECG showed sildenafil did not affect incidence of ventricular arrhythmias. Sildenafil does not alter hemodynamic response to exercise or change incidence of ventricular arrhythmias in men with CVD and ED. These results suggest that, when used in accordance with prescribing information and current treatment guidelines, sildenafil should be safe for most patients with both these conditions.

Relationships between self-reported health related quality of life and measures of standardized exercise capacity and metabolic efficiency in a middle-aged and aged healthy population.

The purpose of this study was to evaluate to what extent self-reported health related quality of life (HRQL), assessed by the Swedish standard version of the Medical Outcome Study Short-Form 36 (SF-36), is related to measured exercise capacity and metabolic efficiency in a cohort of healthy subjects from the Gothenburg area of Sweden. Individuals were invited to take part in the evaluation where HRQL was compared with the maximal power output expressed in Watts assessed during a standardized treadmill test with incremental work loads. Whole body respiratory gas exchanges (CO2/O2) were simultaneously measured. Estimate of metabolic efficiency was derived from oxygen uptake per Watt produced (ml O2/min/W) near maximal work. The health status profile in the current population largely agreed with normative data from an age- and gender-matched reference group, although some measured scores were slightly better than reference scores. Males and females had a similar relationship between energy cost (ml O2/min) for production of maximal work (W), while the regressions for maximal exercise power and age were significantly different between males and females (p < 0.01). The overall metabolic efficiency was the same in individuals between 40 and 74 years of age (10.4 +/- 0.07 ml O2/min/ Watt). Maximal exercise power was only related to the SF-36 subscale physical functioning (PF), but unrelated to other physical subscales such as role limitations due to physical problems, good general health and vitality. There was also a discrepancy between measured maximal power and PF in many subjects, particularly in males who experienced either intact or severely reduced PF. Our results demonstrate that simultaneous measurements of self-reported and objective measures of PF should add a more integrated view for evaluation of therapeutic effectiveness, since the overall correlation was poor between objective and subjective scores among individuals.

Exercise-Induced Renal Tubular Injury in Intermittent Claudication

While, exercise in intermittent claudication (IC) may improve symptoms and exercise tolerance, it has been shown to produce an ischemia-reperfusion injury. This study aimed to assess the impact of this on renal function, by measuring the changes in activity of the urinary enzyme N-acetyl-β-D-glucosaminidase (NAG), a sensitive marker of renal tubular damage. 15 patients with IC and 15 controls underwent a standardized exercise treadmill test. Changes in Ankle/Brachial Pressure Index (ABPI) were measured as was the urinary activity of NAG at rest, and following exercise. While a marked change was seen in ABPI's of the IC group, no change was apparent in the controls. Urinary NAG activity rose significantly in the IC group following exercise (mean 51.25 μmol/h/mmol creatinine) compared with both resting levels (30.4) and with the post-exercise NAG of controls (26.4),P < 0.05. There was no significant difference in NAG levels within the control group (23.5 vs 26.4). Exercise in intermittent claudication is associated with a renal tubular cell injury, which may be related to an ischemia-reperfusion injury.

Utility of blood pressure during submaximal exercise in the risk stratification of patients with high normal blood pressure

High normal blood pressure (BP) is associated with the metabolic syndrome and carries greater risk for developing hypertension and cardiovascular (CV) events. The Trial of Preventing Hypertension (TROPHY) is designed to determine if 2-years treatment with an angiotensin receptor blocker (ARB) reduces the development of high BP in these subjects. This report was generated from baseline data obtained prior to randomization to ARB or placebo in the first 127 subjects in the TROPHY Substudy. Substudy subjects underwent additional measurements of cardiovascular risk factors including a 2-hour oral glucose tolerance test and measurements of BP during a standardized submaximal exercise treadmill test for 6-minutes. The systolic (S)BP response to submaximal exercise is a powerful predictor of CV outcomes. We examined the utility of exercise SBP > as compared to < the 50%ile after 6-minutes submaximal treadmill exercise as a tool for overall risk stratification in the TROPHY Substudy subjects. Key findings are shown in the Table below. Among subjects with high normal BP and of similar age and screening BP status, those with higher SBP values in response to a brief period of submaximal exercise had significantly greater values for other risk factors including BMI, total cholesterol (not shown), and LDL-C. Subjects with higher SBPs during submaximal exercise also had higher plasma insulin concentrations under fasting conditions and following a glucose load. The findings suggest that exercise BP is useful in identifying a subset of subjects with high normal BP that are at greater metabolic risk for CV disease. The results suggest that attempts to quantify the independent contribution of exercise SBP to CV risk should control for body mass index, total and LDL-cholesterol as well as markers of insulin resistance.

Effects of exercise training program on functional capacity and quality of life in patients with peripheral arterial occlusive disease. Evaluation of a pilot project.

In patients with peripheral arterial occlusive disease (PAOD) stage II, exercise training seems to be important to reduce symptoms and improve functional capacity. We evaluated the effects of an out-patient treatment program on walking distance (standardized treadmill testing), training exercise capacity, and disease specific quality of life (PAVK-86 questionnaire). Thirty-one patients aged 70 +/- 2 with intermittent claudicatio in stage IIa/IIb according to Fontaine (n = 18/13) underwent a supervised 12 week exercise training and education outpatient program. During course of intervention, patients demonstrated improvements in pain-free training walking distance (p < 0.001) and repetitions of tiptoe standing (p < 0.05). In standardized treadmill testing, pain-free walking distance was improved by 182% (129 +/- 19 m-->364 +/- 53 m; p < 0.001), and maximum walking distance by 76% (311 +/- 42 m-->546 +/- 63 m; p < 0.01). Before training, mean subscale scores of the PAVK-86 demonstrated distinct impairments concerning pain and functional status. After 12 weeks of intervention, with exception of the subscale complaints, all dimensions of quality of life assessed have improved significantly. The highest effect size was observed for the subscales pain, mood, and functional status. Improvement in the subscale anxiety and pain-free walking distance (treadmill test) correlated significantly (r = 0.46) as well as improvement in the subscale mood and maximum walking distance (r = 0.45). In patients with PAOD stage II considerable effects on functional capacity and important dimensions of quality of life can be achieved by a short exercise and education program.

Pentoxifylline Reverses Oxidative Mitochondrial Defect in Claudicating Skeletal Muscle

Objective. Previous morphologic studies and phosphorus nuclear magnetic resonance spectroscopy (31P MRS) have suggested a primary mitochondrial defect in claudicating skeletal muscle. We hypothesized that pentoxifylline may alleviate this defect.Methods. The response of calf muscle bioenergetics to pentoxifylline was evaluated in 10 male, nondiabetic claudicants with 31P MRS and standard treadmill testing before and after 12 weeks of pentoxifylline therapy. Phosphocreatine (PCr) and adenosinodiphosphate (ADP) recovery rate constants, two very sensitive measures of oxidative mitochondrial function, were measured.Results. Seven of the 10 subjects had abnormal baseline PCr (<0.015 s−1) and ADP (<0.024 s−1) recovery rate constants. These 7 had significant improvement in mitochondrial function with pentoxifylline; their PCr recovery rate constants increased from 0.009 ± 0.002 to 0.013 ± 0.002 s−1 (P = 0.013) and their ADP recovery rate constants increased from 0.015 ± 0.002 to 0.022 ± 0.002 s−1 (P = 0.004). The remaining 3 patients had normal baseline constants and demonstrated no improvement after pentoxifylline therapy. Baseline PCr and ADP recovery rate constants inversely correlated with their corresponding percentage of improvement after pentoxifylline (P < 0.05). In addition the percentage of improvement in the PCr and ADP recovery rate constants correlated with the percentage of improvement in initial claudication distance and maximum walking capacity (P < 0.05).Conclusions. Pentoxifylline improves the mitochondriopathy of claudicating muscle, producing the most improvement in limbs with the worse baseline mitochondrial function. These results point to a potential new mode of action for pentoxifylline in the treatment of claudication and identify a subgroup of patients with the best potential for improvement with treatment.

A new device for the measurement of disease severity in patients with intermittent claudication.

To assess a new method of determining functional impairment in patients with intermittent claudication, the Double Physiological Walking Test (DPWT) using the PADHOC (Peripheral Arterial Disease Holter Control) device, against a standard treadmill test. Patients with intermittent claudication presenting to the department were considered for both the DPWT and a standard treadmill test. initial claudicating distance, maximal walking distance and speed of walking were determined for both parts of the DPWT. Initial claudicating distance and maximal walking distance were determined from the treadmill test. Comparisons were made between the treadmill test and the DPWT. The treadmill test was unable to be performed in 22% of patients due to defined contraindications. There were strong correlations in both walking distances and disease severity when comparing the DPWT and the treadmill test. Patients in whom the treadmill test was contraindicated had significantly shorter walking distances on the DPWT than those who were able to complete a treadmill walking test. The DPWT correlates strongly with walking distances obtained from a standard treadmill test. However, the PADHOC can be used in a number of differing locations and settings as well as in patients in whom a treadmill test is contraindicated. It therefore has a role to play in the initial assessment of patients presenting with intermittent claudication.

Stent placement in short unilateral iliac occlusion. . Technique and 24-month results

Purpose: To determine the success rate and 24-month follow-up results of primary stent implantation for reconstruction of unilateral short iliac occlusion involving the aortic bifurcation. Material and Methods: In 90 patients attempts of percutaneous transluminal recanalization of a short unilateral occlusion of the iliac arteries were performed. In 72/90 patients, the treatment was successful. Stent implantation was performed after recanalization in all 72 patients. Pre-interventional angiography of successfully treated patients showed unilateral occlusions and contralateral stenosis in 34/72 patients. In 38/72 patients unilateral occlusion without contralateral stenosis was diagnosed. The recanalization of the common iliac artery obstructions were performed with a guidewire and excimer laser angioplasty. Totally 152 stents were used for the treatment of iliac occlusion. Standardized treadmill testing and color-coded Doppler ultrasound were performed before treatment and during the follow-up. Results: In all patients, stents were placed successfully; 5 major and 7 minor complications were observed. A clinical improvement of +2 to +3 according to the American Heart Association criteria was observed in 62 and 10 patients, respectively. Angiographic control was performed after 1–30 months. The primary angiographic patency rate was 83.1%. Angiography revealed significant restenoses in 4 patients successfully treated with transluminal angioplasty, and re-occlusion in 6 patients which were referred to surgery. The patency rate after 24 months was 90.0%. Conclusion: Primary stent implantation is an effective treatment for short iliac obstructions and represents a true endovascular alternative to surgery.

Stent placement in short unilateral iliac occlusion. Technique and 24-month results.

To determine the success rate and 24-month follow-up results of primary stent implantation for reconstruction of unilateral short iliac occlusion involving the aortic bifurcation. In 90 patients attempts of percutaneous transluminal recanalization of a short unilateral occlusion of the iliac arteries were performed. In 72/90 patients, the treatment was successful. Stent implantation was performed after recanalization in all 72 patients. Pre-interventional angiography of successfully treated patients showed unilateral occlusions and contralateral stenosis in 34/72 patients. In 38/72 patients unilateral occlusion without contralateral stenosis was diagnosed. The recanalization of the common iliac artery obstructions were performed with a guidewire and excimer laser angioplasty. Totally 152 stents were used for the treatment of iliac occlusion. Standardized treadmill testing and color-coded Doppler ultrasound were performed before treatment and during the follow-up. In all patients, stents were placed successfully; 5 major and 7 minor complications were observed. A clinical improvement of +2 to +3 according to the American Heart Association criteria was observed in 62 and 10 patients, respectively. Angiographic control was performed after 1-30 months. The primary angiographic patency rate was 83.1%. Angiography revealed significant restenoses in 4 patients successfully treated with transluminal angioplasty, and re-occlusion in 6 patients which were referred to surgery. The patency rate after 24 months was 90.0%. Primary stent implantation is an effective treatment for short iliac obstructions and represents a true endovascular alternative to surgery.

Clinical and Exercise Test Predictors of All-Cause Mortality: Results From > 6,000 Consecutive Referred Male Patients

ObjectiveTo report the prevalence of abnormal treadmill test responses and their association with mortality in a large consecutive series of patients referred for standard exercise tests, with testing performed and reported in a standardized fashion. BackgroundExercise testing is widely performed, but few databases exist of large numbers of consecutive tests performed on patients referred for routine clinical purposes using standardized methods. Even fewer of the available databases have information regarding all-cause mortality as an outcome. MethodsAll patients referred for evaluation at two university-affiliated Veterans Affairs medical centers who underwent exercise treadmill testing for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security death index after a mean 6.2 years (median, 7 years) of follow-up. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion using a computer-assisted protocol. All-cause mortality was utilized as the end point for follow-up. Standard survival analysis was performed, including Kaplan-Meier curves and a Cox hazard model. ResultsThere were 6,213 male patients (mean ± SD age, 59 ± 11 years) who underwent standard exercise ECG treadmill testing over the study period with a mean follow-up duration of 6.2 ± 3.7 years. There were no complications of testing in this clinically referred population, 78% of whom were referred for chest pain, or risk factors or signs or symptoms of ischemic heart disease. Overlapping thirds had typical angina or history of myocardial infarction (MI). Five hundred seventy-nine patients had prior coronary artery bypass surgery, and 522 patients had a history of congestive heart failure (CHF). Indications for testing were in accordance with published guidelines. Twenty percent died over the follow-up period, for an average annual mortality rate of 2.6%. Cox hazard function chose the following variables in rank order as independently and significantly associated with time to death: exercise capacity (metabolic equivalents < 5, age > 65 years, history of CHF, and history of MI. A score based on these variables (summing up the four variables [if yes = 1 point]) classified patients into low-risk, medium-risk, and high-risk groups. The high-risk group (score ≥ 3) has a hazard ratio of 5.0 (95% confidence interval, 4.7 to 5.3) and a 5-year mortality rate of 31%. ConclusionThis comprehensive analysis provides rates of various abnormal responses that can be expected in patients referred for exercise testing at a typical medical center. Four simple variables combined as a score powerfully stratified patients according to prognosis.

Characterization of the metabolic demands of simulated shipboard Royal Navy fire-fighting tasks

The purpose of this study was to quantify the metabolic demand of simulated shipboard fire-fighting procedures currently practised by men and women in the Royal Navy (RN) and to identify a minimum level of cardiovascular fitness commensurate with satisfactory performance. Thirty-four males (M) and 15 females (F) volunteered as subjects for this study (n = 49). Maximal oxygen uptake ([Vdot]O2max) and heart rate (fc max) of each subject was assessed during a standardized treadmill test. During the main trials, volunteers were randomly assigned to complete several 4-min simulated shipboard fire-fighting tasks (boundary cooling (BC), drum carry (DC), extinguisher carry (EC), hose run (HR), ladder climb (LC)), at a work rate that was endorsed as a minimum acceptable standard. Heart rate (fc) and oxygen uptake ([Vdot]O2) were recorded at 10-s intervals during rest, exercise and recovery. Participants completed all tasks within an allocated time with the exception of the DC task, where 11 subjects (all females) failed to maintain the endorsed work rate. The DC task elicited the highest (p< 0.01) group mean peak metabolic demand (PMD) in males (43 ml min-1 kg-1) and females (42 ml min-1 kg-1) who were able to maintain the endorsed work rate. The BC task elicited the lowest PMD (23 ml min-1 kg-1), whilst the remaining three tasks elicited a remarkably similar PMD of 38–39 ml min-1 kg-1. The human endurance limit while wearing a self-contained breathing apparatus (SCBA) dictates that RN personnel are only able to fire-fight for 20–30 min, while wearing a full fire-fighting ensemble (FFE) and performing a combination of the BC, HR and LC tasks, which have a group mean metabolic demand of 32.8 ml min-1 kg-1. Given that in healthy subjects fire-fighting can be sustained at a maximum work intensity of 80% [Vdot]O2max when wearing SCBA for this duration, it is recommended that all RN personnel achieve a [Vdot]O2max of 41 ml min-1 kg-1 as an absolute minimum standard. Subjects with a higher [Vdot]O2max than the above quoted minimum are able to complete the combination of tasks listed with greater metabolic efficiency and less fatigue.

Simple Treadmill Score To Diagnose Coronary Disease

Our aim was to derive and validate a simplified treadmill score for predicting the probability of angiographically confirmed coronary artery disease (CAD). The American College of Cardiology/American Heart Association guidelines for exercise testing recommend the use of multivariable equations to enhance the diagnostic characteristics of the standard treadmill test. Most of these equations use complicated statistical techniques to provide diagnostic estimates of CAD. Simplified scores derived from such equations that require physicians only to add points have been developed for pretest estimates of disease and for prognosis. However, no simplified score has been developed specifically for the diagnosis of CAD using exercise test results. Consecutive patients referred for evaluation of chest pain who underwent standard treadmill testing followed by coronary angiography were studied. A logistic regression model was used to predict clinically significant (> or = 50% stenosis) CAD and then the variables and coefficients were used to derive a simplified score. The simplified score was calculated as follows: (6 x maximal heart rate code) + (5 x ST-segment depression code) + (4 x age code) + angina pectoris code + hypercholesterolemia code + diabetes code + treadmill angina index code. The simplified score had a range from 6 to 95, with < 40 designated as low probability, between 40 and 60 was intermediate probability, and > 60 was high probability for CAD. A total of 1,282 male patients without a prior myocardial infarction underwent exercise treadmill testing and coronary angiography in the derivation group, and there were 476 male patients in the validation group from another institution. The area under the receiver operating characteristic curve (+/- SE) for the ST-segment response alone was 0.67 as compared to 0.79 +/- 0.01 for the diagnostic score (p > 0.001). The prevalence of significant disease for the men was 27% in the low-probability group, 62% in the intermediate-probability group, and 92% in the high-probability group, which was similar to the prevalence in the validation group, with 22%, 58%, and 92% in low-, intermediate-, and high-probability groups, respectively. The low-probability group had < 4% prevalence of severe disease. In both populations, 7 more patients out of 100 were correctly classified than with the use of ST-segment criteria. When used as a clinical management strategy, the score has a sensitivity of 88% and a specificity of 96%. This simplified exercise score that estimates the probability of CAD can be easily applied without a calculator and is a useful and valid tool that can help physicians manage patients presenting with chest pain.