Asbjørn Støylen

Superior Cardiovascular Effect of Aerobic Interval Training Versus Moderate Continuous Training in Heart Failure Patients A Randomized Study

Background— Exercise training reduces the symptoms of chronic heart failure. Which exercise intensity yields maximal beneficial adaptations is controversial. Furthermore, the incidence of chronic heart failure increases with advanced age; it has been reported that 88% and 49% of patients with a first diagnosis of chronic heart failure are >65 and >80 years old, respectively. Despite this, most previous studies have excluded patients with an age >70 years. Our objective was to compare training programs with moderate versus high exercise intensity with regard to variables associated with cardiovascular function and prognosis in patients with postinfarction heart failure. Methods and Results— Twenty-seven patients with stable postinfarction heart failure who were undergoing optimal medical treatment, including &bgr;-blockers and angiotensin-converting enzyme inhibitors (aged 75.5±11.1 years; left ventricular [LV] ejection fraction 29%; &OV0312;o2peak 13 mL · kg−1 · min−1) were randomized to either moderate continuous training (70% of highest measured heart rate, ie, peak heart rate) or aerobic interval training (95% of peak heart rate) 3 times per week for 12 weeks or to a control group that received standard advice regarding physical activity. &OV0312;o2peak increased more with aerobic interval training than moderate continuous training (46% versus 14%, P<0.001) and was associated with reverse LV remodeling. LV end-diastolic and end-systolic volumes declined with aerobic interval training only, by 18% and 25%, respectively; LV ejection fraction increased 35%, and pro-brain natriuretic peptide decreased 40%. Improvement in brachial artery flow-mediated dilation (endothelial function) was greater with aerobic interval training, and mitochondrial function in lateral vastus muscle increased with aerobic interval training only. The MacNew global score for quality of life in cardiovascular disease increased in both exercise groups. No changes occurred in the control group. Conclusions— Exercise intensity was an important factor for reversing LV remodeling and improving aerobic capacity, endothelial function, and quality of life in patients with postinfarction heart failure. These findings may have important implications for exercise training in rehabilitation programs and future studies.

Real-Time Strain Rate Imaging of the Left Ventricle by Ultrasound

The regional function of the left ventricle can be visualized in real-time using the new strain rate imaging method. Deformation or strain of a tissue segment occurs over time during the cardiac cycle. The rate of this deformation, the strain rate, is equivalent to the velocity gradient, and can be estimated using the tissue Doppler technique. We present the strain rate as color-coded 2-dimensional cine-loops and color M-modes showing the strain rate component along the ultrasound beam axis. We tested the method in 6 healthy subjects and 6 patients with myocardial infarction. In the healthy hearts, a spatially homogeneous distribution of the strain rate was found. In the infarcted hearts, all the infarcted areas in this study showed up as hypokinetic or akinetic, demonstrating that this method may be used for imaging of regional dysfunction. Shortcomings of the method are discussed, as are some possible future applications of the method.

Segmental and global longitudinal strain and strain rate based on echocardiography of 1266 healthy individuals: the HUNT study in Norway

AIMS To study the distribution of longitudinal systolic strain and strain rate (SR) as indicators of myocardial deformation according to age and sex in a healthy population. METHODS AND RESULTS Longitudinal strain and SR were determined in 1266 healthy individuals from three standard apical views, using a combination of speckle tracking (ST) and tissue Doppler imaging (TDI) to track regions of interest (ROIs). To test applicability of the reference values, we used a subset of the population to compare four methods of assessing myocardial deformation: (1) a combination of TDI and ST; (2) TDI with fixed ROIs; (3) TDI with tracking of ROIs; and (4) ST. Mean (SD) overall global longitudinal strain and SR were -17.4% (2.3) and -1.05 s(-1) (0.13) in women, and -15.9% (2.3) and -1.01 s(-1) (0.13) in men. Deformation indices decreased with increasing age. The combined and ST methods showed identical SR, but values were significantly lower than those obtained by TDI. Strain was overestimated by the ST method (18.4%) compared with the combined method (17.4%). CONCLUSION The reference values for global and segmental longitudinal strain and SR obtained from this population study are applicable for use in a wide clinical setting.

Aerobic interval training reduces blood pressure and improves myocardial function in hypertensive patients

Aims: Exercise is recommended as prevention, management, and control of all stages of hypertension. There are still controversies about the optimal training dose, frequency, and intensity. We aimed to study the effect of aerobic interval training on blood pressure and myocardial function in hypertensive patients. Methods and results: A total of 88 patients (52.0 ± 7.8 years, 39 women) with essential hypertension were randomized to aerobic interval training (AIT) (>90% of maximal heart rate, correlates to 85–90% of VO2max), isocaloric moderate intensity continuous training (MIT) (∼70% of maximal heart rate, 60% of VO2max), or a control group. Exercise was performed on a treadmill, three times per week for 12 weeks. Ambulatory 24-hour blood pressure (ABP) was the primary endpoint. Secondary endpoints included maximal oxygen uptake (VO2max), mean heart rate/24 hour, flow mediated dilatation (FMD), total peripheral resistance (TPR), and myocardial systolic and diastolic function by echocardiography. Systolic ABP was reduced by 12 mmHg (p < 0.001) in AIT and 4.5 mmHg (p = 0.05) in MIT. Diastolic ABP was reduced by 8 mmHg (p < 0.001) in AIT and 3.5 mmHg (p = 0.02) in MIT. VO2max improved by 15% (p < 0.001) in AIT and 5% (p < 0.01) in MIT. Systolic myocardial function improved in both exercise groups, diastolic function in the AIT group only. TPR reduction and increased FMD were only observed in the AIT group. Conclusions: This study indicates that the blood pressure reducing effect of exercise in essential hypertension is intensity dependent. Aerobic interval training is an effective method to lower blood pressure and improve other cardiovascular risk factors.

Automated analysis of myocardial deformation at dobutamine stress echocardiography: an angiographic validation.

OBJECTIVES We investigated the accuracy of automated analysis of myocardial deformation during dobutamine stress echocardiography (DSE). BACKGROUND The time required for segmental measurement of strain rate imaging (SRI) limits its feasibility for quantification of DSE. METHODS Myocardial deformation was assessed at DSE in 197 patients, 76 with and 61 without coronary artery disease (CAD) at angiography, and 60 at low risk of CAD. Automated deformation analysis was based on velocity gradient and segment length methods of measuring longitudinal motion within a region of interest tracked through the cardiac cycle. Results were compared with independent wall motion scoring (WMS). Patients were randomly divided; group A (n = 69) established optimal cutoffs for the parameters and group B (n = 68) tested their accuracy. RESULTS The feasibility of WMS exceeded that of both SRI methods at rest and at peak stress. In group A, the area under the receiver-operating characteristics curve of the peak systolic strain rate was 0.90 by both methods, and the optimal cutoffs for detection of CAD were -1.3 (velocity gradient) and -1.2 s(-1) (segment length). The areas under the receiver-operating characteristics curves for end-systolic strain were less (0.87) by both methods, with respective cutoffs of 9% and 8%. In group B, the velocity and segment length methods had respective sensitivities of 87% and 84% for SR, and 87% and 88% for end-systolic strain. Both significantly exceeded that of WMS in the same group (75%). CONCLUSIONS Automated analysis of myocardial deformation at DSE is feasible and accurate, and may increase the sensitivity of expert conventional reading.

Reference Values and Distribution of Conventional Echocardiographic Doppler Measures and Longitudinal Tissue Doppler Velocities in a Population Free From Cardiovascular Disease

Background—This study aimed to investigate the distribution of conventional Doppler measurements, pulsed wave tissue Doppler imaging (pwTDI)- and color tissue Doppler imaging-derived velocities, by age and sex in a healthy population. Methods and Results—Longitudinal tissue Doppler velocities were determined in 1266 healthy individuals from standard apical 4- and 2-chamber views. By the pwTDI method, mean±SD systolic mitral annular velocities were 8.2±1.3 cm/s in women and 8.6±1.4 cm/s in men, and by color tissue Doppler, they were 6.6±1.1 cm/s in women and 6.9±1.3 cm/s in men. With pwTDI, diastolic early mitral annular velocities were 11.8±3.2 cm/s in women and 10.8±3.0 cm/s in men, with corresponding ratios between mitral early flow velocity and early diastolic tissue velocity of 6.7±0.8 in women and 6.4±0.8 in men. By pwTDI, tricuspid annular systolic and early diastolic velocities were 12.5±1.9 and 13.3±3.0, respectively, in women and 12.8±2.2 and 12.5±3.3, respectively, in men. There was a significant decrease in left and right ventricular function with increasing age. Conclusions—The longitudinal mitral and tricuspid annular velocities from this population study are widely applicable as reference values. Reference values for annular velocities should be specified by sex and age. The average of inferoseptal and anterolateral wall velocities may be the preferred index of left ventricular performance.

Aerobic interval training increases peak oxygen uptake more than usual care exercise training in myocardial infarction patients: a randomized controlled study

Objective: Exercise capacity strongly predicts survival and aerobic interval training (AIT) increases peak oxygen uptake effectively in cardiac patients. Usual care in Norway provides exercise training at the hospitals following myocardial infarction (MI), but the effect and actual intensity of these rehabilitation programmes are unknown. Design: Randomized controlled trial. Setting: Hospital cardiac rehabilitation. Subjects: One hundred and seven patients, recruited two to 12 weeks after MI, were randomized to usual care rehabilitation or treadmill AIT. Interventions: Usual care aerobic group exercise training or treadmill AIT as 4 × 4 minutes intervals at 85–95% of peak heart rate. Twice weekly exercise training for 12 weeks. Main measures: The primary outcome measure was peak oxygen uptake. Secondary outcome measures were endothelial function, blood markers of cardiovascular disease, quality of life, resting heart rate, and heart rate recovery. Results: Eighty-nine patients (74 men, 15 women, 57.4 ± 9.5 years) completed the programme. Peak oxygen uptake increased more (P = 0.002) after AIT (from 31.6 ± 5.8 to 36.2 ± 8.6 mL·kg−1·min−1, P < 0.001) than after usual care rehabilitation (from 32.2 ± 6.7 to 34.7 ± 7.9 mL·kg−1·min−1, P < 0.001). The AIT group exercised with significantly higher intensity in the intervals compared to the highest intensity in the usual care group (87.3 ± 3.9% versus 78.7 ± 7.2% of peak heart rate, respectively, P < 0.001). Both programmes increased endothelial function, serum adiponectin, and quality of life, and reduced serum ferritin and resting heart rate. High-density lipoprotein cholesterol increased only after AIT. Conclusions: AIT increased peak oxygen uptake more than the usual care rehabilitation provided to MI patients by Norwegian hospitals.

Strain Rate Imaging by Ultrasound in the Diagnosis of Regional Dysfunction of the Left Ventricle

Background: Regional strain rate in the left ventricle can be assessed by tissue Doppler velocity gradient and color mapped in real time. Regional contractility thus can be visualized and graded. To validate the method, we made a comparison with standard echocardiography. Methods and Results: Fifteen patients with recent myocardial infarction were examined with the use of strain rate imaging (SRI). Velocity gradients were mapped by color. Gray‐scale imaging was performed using the second harmonic mode. Cine loops of two‐dimensional echocardiography (2‐D echo) and SRI images from three standard apical planes were analyzed offline. A four‐grade scale in 16 segments was used to score wall motion by 2‐D echo and by SRI. Of a total of 236 segments, 235 segments were analyzable by 2‐D echo and 218 segments were analyzable by SRI. Correlation of wall motion score index with ejection fraction was – 0.84 by 2‐D echo and – 0.92 by SRI. One hundred fourteen segments had an equal score by the two methods: 51 segments differed by 1 degree and 14 segments differed by 2 degrees (K = 0.45). Conclusions: SRI agrees well with echocardiography in grading regional wall function, and the method can be seen as validated in a clinical setting for assessment of regional systolic wall function and is demonstrated to be applicable for semiquantitative wall motion assessment. SRI has theoretical advantages and may be a valuable addition to standard echocardiography, especially in the field of stress echocardiography.

Regional myocardial long-axis strain and strain rate measured by different tissue Doppler and speckle tracking echocardiography methods: a comparison with tagged magnetic resonance imaging

AIMS Compare four different echocardiographic methods, based on tissue Doppler imaging (TDI) and speckle tracking (ST) separately or combined, for long-axis strain and strain rate (SR) measurements, using magnetic resonance imaging (MRI) tagging as a reference. METHODS AND RESULTS In 21 subjects (10 with myocardial infarction) peak systolic strain and systolic and early diastolic SR were measured by four different echo methods: (i) two-dimensional (2D) strain (B-mode); (ii) ST (custom software) of segment end-points (B-mode); (iii) similar to (ii), but combining ST with tissue Doppler tracking; (iv) strain from tissue Doppler velocity gradients (VG). Agreement with MRI tagging was better for strain than for SR. Ninety-five per cent limits of agreement were wider for the TDI-VG method, and 2D strain showed negative bias compared with MRI tagging and the other echo methods. Reproducibility was better for 2D strain than for MRI tagging and the other echo methods. CONCLUSION ST alone or combined with TDI seems to be suitable for automated measurements of regional myocardial deformation. The study gives important information on the strengths and weaknesses of the different methods, which is important for further development to increase accuracy and applicability.

Age‐predicted maximal heart rate in healthy subjects: The HUNT Fitness Study

Maximal heart rate (HRmax) declines substantially with age, but the magnitude and possible modifying effect of gender, body composition, and physical activity are not fully established. The present study examined the relationship between HRmax and age in 3320 healthy men and women within a wide age range using data from the HUNT Fitness Study (2007–2008). Subjects were included if a maximal effort could be verified during a maximal exercise test. General linear modeling was used to determine the effect of age on HRmax. Subsequently, the effects of gender, body mass index (BMI), physical activity status, and maximal oxygen uptake were examined. Mean predicted HRmax by three former prediction formulas were compared with measured HRmax within 10‐year age groups. HRmax was univariately explained by the formula 211 − 0.64·age (SEE, 10.8), and we found no evidence of interaction with gender, physical activity, VO2max level, or BMI groups. There were only minor age‐adjusted differences in HRmax between these groups. Previously suggested prediction equations underestimated measured HRmax in subjects older than 30 years. HRmax predicted by age alone may be practically convenient for various groups, although a standard error of 10.8 beats/min must be taken into account. HRmax in healthy, older subjects and women were higher than previously reported.