Systolic Time Intervals and New Measurement Methods

Abstract

Systolic time intervals have been used to detect and quantify the directional changes of left ventricular function. New methods of recording these cardiac timings, which are less cumbersome, have been recently developed and this has created a renewed interest and novel applications for these cardiac timings. This manuscript reviews these new methods and addresses the potential for the application of these cardiac timings for the diagnosis and prognosis of different cardiac diseases.

Systolic time intervals derived from electrocardiographic gated intra-renal artery Doppler waveform associated with left ventricular systolic function

“…Cardiac STIs affected by many physiological and pharmacologic factors are well-established parameters in assessment of global cardiac performance329303132. In general, cardiac STIs may be affected by several medications, such as digitalis glycosides, catecholamines, propranolol, amyl nitrate, and calcium gluconate, through positive or negative inotropic effects3132.…”

“…The physiological meaning of cardiac PEP is composed of isovolumetric contraction time and electromechanical delay, i.e. time interval between initiation of ventricular depolarization and aortic valve opening32933. Regardless of causes of heart failure, increased cardiac PEP is resulted from a decreased rate of left ventricular pressure rise (dP/dt) during isovolumic contraction period334.…”

“…Although the physiological meaning of cardiac ET is the period from beginning to finishing of left ventricular ejection, the factors contributed to ET are more complex3. The length of PEP, preload condition, strength of myocardial fiber, and inotropic agents are associated with ET period329. Unlike PEP, which respectively became shorten and lengthen by positive and negative inotropic agents, ET became shorten both by positive and negative inotropic agents3536.…”

Automatic Identification of Systolic Time Intervals in Seismocardiogram

“…1(b) are pre-ejection period, left ventricular ejection time and electro-mechanical systole. These intervals are known as STI2425 and its derivation from SCG and ECG has been successfully demonstrated5262728. Accurate measurement of STI is important as any deviation of STI trend can correspond to an abnormality of the heart function25.…”

“…STI has been useful in numerous applications such as cardiac computed tomographic gating30, identification of exercise capacity31, optimization of cardiac resynchronization therapy in heart failure patients24, identifying extent of left ventricular (LV) muscle dysfunction24, observing changes in LV performance during haemodialysis32, mitral valve stenosis33, atrial fibrillation34, coronary artery disease35 and detection of ischemia1736 etc. Further, in the context of personal health monitoring from wearable sensors, non-invasive and unobtrusive measurement of STI can provide a quantified measure of cardiac health2428. However, deriving STI from SCG and ECG requires careful annotation for their utilization in such applications.…”