title: Exercise central (aortic) blood pressure is predominantly driven by forward traveling waves, not wave reflection.
abstract: Exercise hypertension independently predicts cardiovascular mortality, although little is known about exercise central hemodynamics. This study aimed to determine the contribution of arterial wave travel and aortic reservoir characteristics to central blood pressure (BP) during exercise. We hypothesized that exercise central BP would be principally related to forward wave travel and aortic reservoir function. After routine diagnostic coronary angiography, invasive pressure and flow velocity were recorded in the ascending aorta via sensor-tipped intra-arterial wires in 10 participants (age, 55±10 years; 70% men) free of coronary artery disease with normal left ventricular function. Measures were recorded at baseline and during supine cycle ergometry. Using wave intensity analysis, dominant wave types throughout the cardiac cycle were identified (forward and backward, compression, and decompression), and aortic reservoir and excess pressure were calculated. Central systolic BP increased significantly with exercise (Δ=19±12 mm Hg; P<0.001). This was associated with increases in systolic forward compression waves (Δ=12×10(6)±17×10(6) W·m(-2)·s(-1); P=0.045) and forward decompression waves in late systole (Δ=9×10(6)±6×10(6) W·m(-2)·s(-1); P<0.001). Despite significant augmentation in BP (Δ=9±6 mm Hg; P=0.002), reflected waves did not increase in magnitude (Δ=-1×10(6)±3×10(6) W·m(-2)·s(-1); P=0.2). Excess pressure rose significantly with exercise (Δ=16±9 mm Hg; P<0.001), and reservoir pressure integral fell (Δ=-5×10(5)±5×10(5) Pa·s; P=0.010). Change in reflection coefficient negatively correlated with change in central systolic BP (r=-0.68; P=0.03). We conclude that elevation of exercise central BP is principally because of increases in aortic forward traveling waves generated by left ventricular ejection. These findings have relevance to understanding central BP waveform morphology and pathophysiology of exercise hypertension.
authors.affiliation: Menzies Research Institute Tasmania, University of Tasmania, Private Bag 23, Hobart 7000, Australia.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Schultz
authors.forename: Justin E
authors.initials: JE
authors.lastname: Davies
authors.forename: Phillip
authors.initials: P
authors.lastname: Roberts-Thomson
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Black
authors.forename: Alun D
authors.initials: AD
authors.lastname: Hughes
authors.forename: James E
authors.initials: JE
authors.lastname: Sharman
mesh_terms: D001013:Aorta, Thoracic / Q000503:physiopathology*; D062186:Arterial Pressure / Q000502:physiology*; D001783:Blood Flow Velocity; D001795:Blood Pressure Determination / Q000379:methods*; D017023:Coronary Angiography; D003327:Coronary Disease / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged
keywords: aorta; blood pressure; exercise; pulse wave analysis; venous reservoirs; wave intensity; wave reflection