Apex techniques, old and new, hold the key to estimated left ventricular end-diastolic and right ventricular systolic pressure

Abstract

The clinical syndrome of heart failure is characterised by a raised venous pressure, dilated ventricular cavity, and exercise intolerance. Raised left ventricular (LV) end-diastolic pressure and high left atrial pressure suggest a poor prognosis [1, 2]. Detection of raised filling pressures are important not only in the progression of coronary artery disease and dilated cardiomyopathy, but also because recent evidence suggests that restrictive LV filling may predict non-responders [3] to the increasingly popular intervention of cardiac resynchronisation therapy. Measurements of ventricular long axis function rely on the fact that the cardiac apex is fixed with respect to the chest wall [4]. Atrio-ventricular coupling during systole and diastole is mediated by an anatomically distinct set of sub-endocardial and sub-epicardial fibres organised longitudinally from base to apex [5]. Systolic function is quantified by familiar measurements such as ejection fraction, fractional shortening or peak rate of pressure change (dp/ dt). Wiggers [6] defined diastole as the period in the cardiac cycle from the ‘‘end of aortic ejection until the onset of ventricular tension development’’. Diastole is a complex sequence involving mechanisms of restoring forces and ventricular compliance, changes in atrial and ventricular pressure, transmitral filling, ventricular interaction, and atrial mechanical activity [1]. Consequently, diastolic function has proved more elusive to quantify, accumulating a stable of surrogates indicative of left atrial (LA) pressure, left ventricular end-diastolic pressure (LVEDP), transmitral flow velocities or long axis function. Assessment is further complicated because abnormalities observed in diastole may arise during the isovolumic periods, as well as in systole. Diastolic function is far more age-dependent than systolic function because physiologically normal values in the young may indicate pathologies in the elderly [1]. Isovolumic relaxation time (from A2 [end of ejection] to mitral cusp separation on M-mode) shortens with raised left atrial pressure, but prolongs with age. Normal ranges for isovolumic relaxation time are 60 – 20 ms (M-mode) [1] or 85 – 15 ms (Doppler) [7]; values less than 40 ms indicate raised left atrial pressure, and zero isovolumic relaxation R. Chung AE M. Y. Henein (&) National Heart and Lung Institute, Department of Echocardiography, Royal Brompton Hospital, Sydney Street, SW3 6NP London, UK e-mail: m.henein@rbht.nhs.uk Int J Cardiovasc Imaging (2006) 22: 643–646 DOI 10.1007/s10554-006-9097-4