The importance of long axis function -an echocardiographic study with respect to ageing, response to treatment, prediction of survival and effect of warm water immersion

Abstract

Echocardiographic M-mode measurement of atrioventricular plane displacement (AVPD) and determination of annular velocity with Tissue Doppler imaging (TDI) is a reliable method to gauge ventricular long axis function for quantification of myocardial contractility and relaxation. The aim of this thesis was to increase the understanding of the importance of long axis function with respect to ageing, response to pharmacological treatment, prediction of survival, and enhanced load condition caused by warm water immersion. In 82 healthy subjects, we observed a decrease in systolic and diastolic long axis function with advancing age, whereas short axes function remained unchanged. A remodelling of the heart towards a more spherical shape was associated with age, and was also shown to be more pronounced in female subjects. In 24 patients with dilated cardiomyopathy, we demonstrated a significant recovery of left ventricular systolic and diastolic long axis function after 6 months of treatment with the β1-adrenoceptor antagonist metoprolol. The improvement was observed both at rest and during pharmacological stress. The relative improvement at rest in the long axis function was 38%, compared with 20% in left ventricular ejection fraction (biplane Simpson). In a multivariate regression analyse we found, in 228 patients with chronic heart failure, that systolic long axis function was an independent predictor of 10-year survival. Acute immersion in warm water caused favourable hemodynamic effects in 18 patients with chronic heart failure. Despite increased preload, long axis function improved in both chambers, most likely caused by a combination of reduced heart rate and decreased afterload. Further, we observed in 12 of these patients, that repeated exposure to increased preload (8 weeks of hydrotherapy twice times weekly) was well tolerated. In summary, these results emphasise that observation of long axis function give information about cardiac function that is not readily available in conventional measurements. Also, registration of long axis function appears to be superior to detect minor ventricular changes.