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Time-varying myocardial stress and systolic pressure-stress relationship: role in myocardial-arterial coupling in hypertension.

Abstract：

BACKGROUND:Myocardial afterload depends on left ventricular (LV) cavity size, pressure, and wall thickness, all of which change markedly throughout ejection. We assessed the relationship between instantaneous ejection-phase pressure and myocardial stress and the effect of arterial wave reflections on myocardial stress in hypertensive and normotensive adults. METHODS AND RESULTS:We studied 42 untreated hypertensive, 42 treated hypertensive, and 42 normotensive adults with normal LV ejection fraction. Time-resolved central pressure, flow, and LV geometry were measured with carotid tonometry, Doppler, and speckle-tracking echocardiography for computation of arterial load and time-varying circumferential and longitudinal myocardial stress. In all 3 groups, peak myocardial stress typically occurred in early systole (within the first 100 milliseconds of ejection), followed by a marked midsystolic shift in the pressure-stress relationship, which favored lower late systolic stress values (P<0.001) relative to pressure. The mean magnitude of this midsystolic shift was quantitatively important in all 3 groups (circumferential stress, 144 to 148 kdynes/cm(2)) and was independently predicted by a higher LV ejection fraction and ratio of LV end-diastolic cavity to wall volume. Time of peak myocardial stress independently correlated with time of the first systolic but not with time of the second systolic central pressure peak. CONCLUSIONS:Peak myocardial stress occurs in early systole, before important contributions of reflected waves to central pressure. In the presence of normal LV ejection fraction, a midsystolic shift in the pressure-stress relationship protects cardiomyocytes against excessive late systolic stress (despite pressure augmentation associated with wave reflections), a coupling mechanism that may be altered in various disease states.

journal_name

Circulation

journal_title

Circulation

authors

Chirinos JA,Segers P,Gupta AK,Swillens A,Rietzschel ER,De Buyzere ML,Kirkpatrick JN,Gillebert TC,Wang Y,Keane MG,Townsend R,Ferrari VA,Wiegers SE,St John Sutton M

doi

10.1161/CIRCULATIONAHA.108.829366

subject

Has Abstract

pub_date

2009-06-02 00:00:00

pages

2798-807

issue

eissn

0009-7322

issn

1524-4539

pii

CIRCULATIONAHA.108.829366

journal_volume

119

pub_type

杂志文章

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Time-varying myocardial stress and systolic pressure-stress relationship: role in myocardial-arterial coupling in hypertension.