Effect of plasma triglycerides on the central haemodynamic response to exercise
 James Sharman
Study Aims
Simultaneous measures of central BP and echocardiography will be recorded at rest and during light exercise in 25 healthy middle aged men following an acute rise in plasma triglycerides. Transient hypertriglyceridaemia will be induced by IV infusion of ClinOleic 20%. Response to this intervention will be compared to a control infusion of normal saline in a randomised, double-blind, placebo controlled, cross-over design. The optimum time to perform post treatment recordings will be clarified in a pilot study (n = 6) to determine serum triglyceride dose-response curves in response to ClinOleic 20%. The IV approach is preferred over oral feeding to rule out the potential confounding influence of vasoactive substances released from the gut in response to nutrients.
Power Calculations. Our primary outcome measure is central SBP during exercise at 60% of age-predicted maximal heart rate. From our previous work in middle aged men exercising at this intensity, we determined this to be 133 ± 14 mmHg. From these data, with a = 0.001, we calculate that 25 subjects would be required to detect a 10% difference with 80% power. Smaller numbers are needed to detect significant differences in exercise AIx.
Study Aims
- To determine the role of serum triglycerides on central SBP during light aerobic exercise.
- To determine the role of serum triglycerides on arterial wave reflection (AIx) during light aerobic exercise.
- To determine the role of serum triglycerides on peripheral vascular resistance and cardiac output during light aerobic exercise.
- To determine the role of serum triglycerides on left ventricular end systolic stiffness, arterial compliance and myocardial energetics during light aerobic exercise.
Hypotheses & Hypotheses Testing
- An acute rise in serum triglycerides will increase central SBP and central pulse pressure during light aerobic exercise. To test this, central BP will be measured at rest and during light exercise (cycling) under conditions of raised serum triglycerides compared to control.
- An acute rise in serum triglycerides will increase arterial wave reflection (AIx) during light aerobic exercise. To test this, AIx will be measured at rest and during light exercise (cycling) under conditions of raised serum triglycerides compared to control.
- An acute rise in serum triglycerides will increase peripheral vascular resistance but not affect cardiac output during light aerobic exercise. To test this, peripheral vascular resistance and cardiac output will be measured using echocardiography and radial tonometry at rest and during light exercise (cycling) under conditions of raised serum triglycerides compared to control.
- An acute rise in serum triglycerides will increase left ventricular end systolic stiffness, reduce arterial compliance and reduce myocardial energetics during light aerobic exercise. To test this, pressure-volume loops will be constructed non-invasively using simultaneous echocardiography and radial tonometry at rest and during light exercise (cycling) under conditions of raised serum triglycerides compared to control.
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