Analysis of right ventricular function in the exercising horse: use of the Fourier Transform

Abstract

Summary The objective of this study was to develop and test a technique to allow dynamic cardiac function to be studied during exercise in the horse. Blood pressure waveforms in the exercising horse are difficult to interpret because of the large influence of stride and respiration. A method has been devised to study dynamic right ventricular variables during high‐speed exercise in the horse. A Fast Fourier Transform was performed on the digitised pressure waveforms and the frequency components associated with stride and respiration were removed. An inverse Fourier Transform was then performed to generate a time‐domain pressure signal. Several dynamic right ventricular variables were calculated using the derived signal. Various parameters associated with removing frequencies from the frequency‐domain pressure signal were changed to determine their influence on the variables. Most of the variables were not sensitive to these parameters. When compared during separate exercise bouts, some variables differed among runs, while others were not significantly different. Using the signal separation technique described here, right ventricular function of an exercising horse can be critically analysed.

Right ventricular pressure dynamics during exercise: relationship to stress echocardiography

“…For the test, each horse galloped at 110% of the speed necessary to elicit VO 2max for 2 min. Analogue RV pressure signals were filtered with a low-pass filter set at 100 Hz and digitised at a sampling rate of 500 Hz, as described in Weigle et al (2000). Signals were recorded continuously on a computerbased data acquisition system 8 .…”

“…A number of sensitive indicators of ventricular function have been proposed. The maximal rate that ventricular pressure is developed (dP/dtmax), the maximal rate of ventricular relaxation (dP/dtmin), the time constant for ventricular relaxation (tau), and maximal and minimal ventricular pressures have all been used to describe ventricular function in horses Grubb et al 1999;Weigle et al 2000). Additionally, several authors have reported the use of right ventricular dP/dtmax to evaluate myocardial function in resting or submaximally exercising horses (Wagner et al 1991;Hinchcliff et al 1995;Grubb et al 1996;Nollet et al 1999).…”

“…However, the accurate analysis of these measurements in maximally exercising horses has been confounded by several variables, such as pressure forces generated by footfall, skeletal muscular contraction and respiratory motion. Recently, Weigle et al (2000) described a method for mathematically separating the effects of footfall and/or respiration frequency from that of the cardiac frequency, thereby providing a viable method of evaluating ventricular function during exercise.…”

Effect of body incline on cardiac performance

“…Maximal HR was determined from the pulmonary arterial pressure waveform. Pulmonary arterial pressure waveforms were Fourier transformed to allow independent analysis of the underlying cardiac, respiratory and stride frequencies (Weigle et al 2000). At maximal exercise, the peak around 2 Hz is associated with respiratory and stride frequency and the peak around 4 Hz is the cardiac frequency.…”

Heart rate of Mangalarga Marchador mares under marcha test and supplemented with chrome

“…Also, the observation of physiological adaptations to the systematic exercise is an important tool in evaluating the sportive performance of athlete horse (Baldissera, 1997). The heart rate influences physiologic alterations that occurs before and after the exercise and the speed of its return depends on the exercise intensity and duration, the animal conditioning and the environmental conditions (Weigle et al, 2000).…”