Katarina Steding

Relation between cardiac dimensions and peak oxygen uptake

BackgroundLong term endurance training is known to increase peak oxygen uptake () and induce morphological changes of the heart such as increased left ventricular mass (LVM). However, the relationship between and the total heart volume (THV), considering both the left and right ventricular dimensions in both males and females, is not completely described. Therefore, the aim of this study was to test the hypothesis that THV is an independent predictor of and to determine if the left and right ventricles enlarge in the same order of magnitude in males and females with a presumed wide range of THV.Methods and ResultsThe study population consisted of 131 subjects of whom 71 were athletes (30 female) and 60 healthy controls (20 female). All subjects underwent cardiovascular MR and maximal incremental exercise test. Total heart volume, LVM and left- and right ventricular end-diastolic volumes (LVEDV, RVEDV) were calculated from short-axis images. was significantly correlated to THV, LVM, LVEDV and RVEDV in both males and females. Multivariable analysis showed that THV was a strong, independent predictor of (R2 = 0.74, p < 0.001). As LVEDV increased, RVEDV increased in the same order of magnitude in both males and females (R2 = 0.87, p < 0.001).ConclusionTotal heart volume is a strong, independent predictor of maximal work capacity for both males and females. Long term endurance training is associated with a physiologically enlarged heart with a balance between the left and right ventricular dimensions in both genders.

Aspects of Left Ventricular Morphology Outperform Left Ventricular Mass for Prediction of QRS Duration

Background: The knowledge of the case‐specific normal QRS duration in each individual is needed when determining the onset, severity and progression of the heart disease. However, large interindividual variability even of the normal QRS duration exists. The aims of the study were to develop a model for prediction of normal QRS complex duration and to test it on healthy individuals.

Peak oxygen uptake in relation to total heart volume discriminates heart failure patients from healthy volunteers and athletes

BackgroundAn early sign of heart failure (HF) is a decreased cardiac reserve or inability to adequately increase cardiac output during exercise. Under normal circumstances maximal cardiac output is closely related to peak oxygen uptake (VO2peak) which has previously been shown to be closely related to total heart volume (THV). Thus, the aim of this study was to derive a VO2peak/THV ratio and to test the hypothesis that this ratio can be used to distinguish patients with HF from healthy volunteers and endurance athletes. Thirty-one patients with HF of different etiologies were retrospectively included and 131 control subjects (60 healthy volunteers and 71 athletes) were prospectively enrolled. Peak oxygen uptake was determined by maximal exercise test and THV was determined by cardiovascular magnetic resonance. The VO2peak/THV ratio was then derived and tested.ResultsPeak oxygen uptake was strongly correlated to THV (r2 = 0.74, p < 0.001) in the control subjects, but not for the patients (r2 = 0.0002, p = 0.95). The VO2peak/THV ratio differed significantly between control subjects and patients, even in patients with normal ejection fraction and after normalizing for hemoglobin levels (p < 0.001). In a multivariate analysis the VO2peak/THV ratio was the only independent predictor of presence of HF (p < 0.001).ConclusionsThe VO2peak/THV ratio can be used to distinguish patients with clinically diagnosed HF from healthy volunteers and athletes, even in patients with preserved systolic left ventricular function and after normalizing for hemoglobin levels.

Respiratory indices by gas analysis and fat metabolism by indirect calorimetry in normal subjects and triathletes

Background:  The effects of exercise on different indices reflecting the metabolism have been of interest for a long time, and a relationship between anaerobic indices and maximal oxygen uptake has been established. The inter‐relationship between different respiratory indices during an exercise test remains to be studied in order to understand differences between individuals. Therefore, the aim of this study was to determine three respiratory indices and investigate their inter‐relationship in individuals with highly variable working capacity. A second aim was to investigate the fat metabolism at the VO2 corresponding to the respiratory compensation point (Pq) in the different subjects using indirect calorimetry.

Quantification of the contribution of septal movement to stroke volume in healthy subjects, athletes, patients with pulmonary insufficiency and patients with pulmonary hypertension

Background In theory, movement of the septum contributes to left ventricular stroke volume (LVSV) if the movement is toward the left ventricle (LV) in systole. If the septum movement is toward the right ventricle (RV), as in dyssynchrony, the septal contribution to LVSV decreases. In patients with increased volume load of the RV the septum may move towards the RV and contribute to right ventricular stroke volume RVSV) at the expense of LVSV. The amount of contribution to stroke volume from septal movement is not kown. The aim of the study was to quantify the percentage of the left ventricular stroke volume, that is derived by the septal movement during systole, in healthy volunteers and patients with volume or pressure load of the RV. Methods Cardiac MRI was used for three-dimensional assessment of cardiac volumes and septal movement. Four groups were examined; healthy subjects (n=29), athletes with high aerobic capacity (n=12), patients with an increased right ventricular volume load from moderate or severe pulmonary insufficiency (PI) in surgically corrected tetralogy of Fallot (n=20) and surgically corrected pulmonary stenosis (PS) (n=2) and patients with an increased right ventricular pressure overload secondary to pulmonary hypertension (n=11). LVSV was calculated by delineation of the endocardium of the LV in diastole and systole. The border between the LV and RV, i.e. the epicardial contour of the septum was delineated in diastole and systole from the apex to the base. Thereby the three-dimensional volume, derived from septal movement, was quantified. Results Septal movement contributed to 8.7±0.7% of stroke volume in healthy subjects and 7.5±0.6% in athletes (p=ns). However, in patients with PI because of surgically corrected tetralogy of Fallot or PS, the septum contributes to right ventricular stroke volume by 14.1±1.7% (p<0.001 compared to healthy subjects). In patients with pulmonary hypertension the contribution to LVSV was 2.5±2.5% (p<0.001 compared to healthy subjects) with a wide range (19% to -9%) of left ventricular stroke volume.

Cardiac reserve index as a novel method for diagnosing heart failure: a cardiac magnetic resonance study in heart failure patients, healthy volunteers and athletes

Results Peak oxygen uptake was strongly correlated to THV (r2 = 0.74, P < 0.001) in the control subjects, but not for the patients (r2 = 0.0006, p = 0.90). The cardiac reserve index differed significantly between control subjects and patients (Figure 1A), even in patients with normal ejection fraction and after normalizing for hemoglobin levels (P < 0.001, Figure 1B). In both figures, the box represents the median, the 25th and the 75th percentile and the whiskers represent minimum and maximum values. In a multivariate analysis the cardiac reserve index was the only independent predictor of presence of HF (P < 0.001).

Regional myocardial strain at rest as assessed by velocity-encoded CMR remain unchanged in endurance trained athletes compared to normal subjects

Methods Seventeen professional soccer and handball players competing on elite level (7 females) and 17 ageand gendermatched control subjects were included in the study. All subjects underwent CMR imaging at rest. Regional left ventricular function was assessed using VE-CMR and expressed as peak, longitudinal and radial strain for each of the standard 17 left ventricular segments. Left ventricular mass (LVM), left ventricular end-diastolic volume (EDV), left ventricular stroke volume (SV), left ventricular ejection fraction (EF) were determined by CMR cine imaging.