General anesthesia and positive pressure ventilation suppress left and right ventricular myocardial shortening in patients without myocardial disease- A strain echocardiography study

Abstract

Background: Myocardial deformation imaging using speckle-tracking echocardiography to assess global longitudinal strain (GLS) is today considered a more sensitive measure of left ventricular (LV) systolic function than ejection fraction. General anesthesia and positive pressure ventilation (PPV) are known to change the right ventricular (RV) and LV loading conditions. However, little is known about the effects of anesthesia and PPV on RV free wall and LV GLS. We studied the influence of general anesthesia and PPV on RV and LV longitudinal strain in patients without myocardial disease. Methods: Twenty-one patients scheduled for non-cardiac surgery were included. The baseline examination was performed on the un-premedicated patients within 60 min of anesthesia. The second examination was performed 10-15 min after induction of anesthesia (propofol, remifentanil), intubation and start of PPV. The examinations included apical four-, two- A nd three-chamber projections, mitral and aortic Doppler flow velocities and tissue Doppler velocities of tricuspid and mitral annulus. LV end-systolic elastance (Ees) and aortic elastance were determined (Ea). Results: General anesthesia and PPV reduced the mean arterial blood pressure (-29%, p < 0.0019), stroke volume index (-13%, p < 0.001) and cardiac index (-23%, p < 0.001). RV end-diastolic area index and LV end-diastolic volume index decreased significantly, while systemic vascular resistance was not significantly affected. Ees decreased significantly with the induction of anaesthesia (-23%, p = 0.002), while there was a trend for a decrease in Ea (p = 0.053). The ventriculo-arterial coupling, Ea/Ees, was not significantly affected by the anesthetics and PPV. The LV GLS decreased from-19.1 ± 2.3% to-17.3 ± 2.9% (p < 0.001) and RV free wall strain decreased from-26.5 ± 3.9% to-24.1 ± 4.2% (p = 0.001). One patient (5%) had at baseline a LV GLS >-16% compared with 6 patients (28%) during general anesthesia and PPV. Three patients (14%) had a RV free wall strain >-24% compared to 8 patients (38%) during general anesthesia and PPV. Conclusions: General anesthesia and PPV reduces systolic LV and RV function to levels considered indicating dysfunction in a substantial proportion of patients without myocardial disease.