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- Title
The impact of an experimentally induced increase in arterial blood pressure on left ventricular twist mechanics.
- Authors
Balmain, B.; Stewart, G. M.; Yamada, A.; Chan, J.; Haseler, L. J.; Sabapathy, S.
- Abstract
The effects of isometric hand-grip exercise (IHG) coupled with a period of postexercise circulatory occlusion (OCC; known to sustain exercise-induced increases in blood pressure while facilitating a decrease in heart rate) on left ventricular (LV) twist mechanicswas examined. Two-dimensional speckle-tracking echocardiography was used to assess LV apical and basal rotation and LV twist in 19 healthy participants (23 ± 2 years old) at rest, during 3 min of IHG (performed at 40% maximal voluntary contraction) and 3 min of OCC immediately following IHG. The IHG elicited significant (P < 0.001) increases in mean arterial pressure (rest, 91 ± 1 mmHg; IHG, 122 ± 2 mmHg) and heart rate (rest, 65 ± 2 beats min-1; IHG, 91 ± 4 beats min-1). Mean arterial pressure remained elevated during OCC (116 ± 2 mmHg; P < 0.001 versus rest), whereas heart rate returned to resting levels (68 ± 3 beats min-1; P=0.159 versus rest). Apical rotation decreased significantly (P<0.01) by 10±5% during IHG and 21±4%duringOCC,whereasbasal rotationremained unchanged fromrest. Left ventricular twist decreased from rest to IHG (12 ±5%; P = 0.015) and OCC (21 ± 4%; P = 0.001), whereas a decrease in LV untwist rate was observed only during OCC. An increase in blood pressure generated by IHG, and maintained by a period of OCC, impairs aspects of LV twist mechanics. Postexercise circulatory occlusion isolated the effect of the arterial blood pressure rise (from heart rate),magnifying the impairment of LV twistmechanics when compared with IHG, whilst also negatively impacting LV relaxation. We propose that a protocol using isometric exercise followed by circulatory occlusion provides a method for studying the effects of blood pressure changes on LV twist mechanics.
- Subjects
BLOOD pressure; LEFT heart ventricle; ECHOCARDIOGRAPHY; HEART beat; BLOOD circulation; ADRENERGIC receptors
- Publication
Experimental Physiology, 2016, Vol 101, Issue 1, p124
- ISSN
0958-0670
- Publication type
Article
- DOI
10.1113/EP085423