Echocardiographic Assessment
A protocol for evaluating performance during diastole by intraoperative
TEE was introduced at JHH in January 2017 and intended for all patients
undergoing CAB surgery. Examinations were performed after induction of
anesthesia and prior to coronary artery revascularization, i.e. prior to
CPB, though timing in relation to sternotomy or phase of respiratory
cycle were not standardized. All TEEs were performed by physicians
NBE-certified in advanced perioperative TEE or by cardiac anesthesia
fellows under the direct supervision of a certified physician. Metrics
of performance during diastole were interpreted by a single physician
(JMD) blinded to each subject’s preoperative comorbidities and
postoperative course. The TEE evaluation of performance during diastole
was modified from that of Swaminathan et al
[14] and included: 1) spectral pulsed
wave Doppler velocity of transmitral early (E) inflow; 2) spectral
tissue Doppler imaging of diastolic myocardial velocity at the lateral
mitral annulus (e’). Unless atrial fibrillation was present, the most
representative waves were chosen. In the case of atrial fibrillation,
values were averaged over 6-7 beats. Abnormal performance during
diastole, hereafter referred to as diastolic dysfunction, was defined
dichotomously as e’ < 10 cm/s. If LV dysfunction during
diastole existed unlike during systole when it was normal, severity was
defined as: 1) Grade 1 if E/e’ < 8.5; 2) Grade 2 if
E/e’ 8.6-12.5; 3) Grade 3 if E/e’ > 12.6. These
compromise E/e’ cutoffs were chosen to accommodate noninteger values not
specifically categorized in the reference manuscript
[14]. Abnormal E was defined
dichotomously as E > 50 cm/sec
[15].