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Load‐dependence of myocardial deformation variables – a clinical strain‐echocardiographic study
Author(s) -
Fredholm M.,
Jörgensen K.,
Houltz E.,
Ricksten S.E.
Publication year - 2017
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/aas.12954
Subject(s) - preload , afterload , medicine , cardiology , heart rate , blood pressure , diastole , anesthesia , hemodynamics
Background The effects of left ventricular (LV) loading on myocardial deformation variables are not well‐studied in the clinical setting. In the present study, we evaluated the effects of isolated changes in preload, afterload and heart rate on LV longitudinal strain, systolic (SR‐S) and early diastolic strain rate (SR‐E) in post‐cardiac surgery patients. Methods Twenty‐one patients were studied early after cardiac surgery. Longitudinal myocardial strain and SR were analysed off‐line using 2‐D speckle echocardiography. The experimental protocol consisted of three consecutive interventions: (1) preload was increased by passive leg elevation, (2) afterload was increased by an infusion of phenylephrine to increase arterial blood pressure by 10–15% and (3) heart rate was increased 10% and 20% by atrial pacing. During both the preload and afterload challenges heart rate was kept constant by atrial pacing. Central venous pressure was kept constant during pacing by infusion of hetastarch/albumin. Results The increase in preload increased LV strain, SR‐S and SR‐E by 20%, 11% and 17%, respectively. The phenylephrine‐induced increase in afterload, did not affect LV strain, SR‐S or SR‐E. LV strain was not affected while SR‐S and SR‐E increased by pacing‐induced heart rate increase. Conclusion After cardiac surgery, systolic and early diastolic strain rate are dependent on both preload and heart rate, while neither of these variables was afterload‐dependent. LV strain was preload‐dependent but not affected by atrial pacing. When evaluating the direct effects of various pharmacological or other interventions on myocardial contractility and relaxation, preload and heart rate must be controlled.