Myocardial dysfunction after CPB is a common but not universal occurrence. The ability to predict which patients need vasopressor or inotropic support after CPB would be useful. We would then avoid discovering the need for such support when attempts to wean from CPB without these drugs results in hypotension and myocardial failure. This predictive ability would also benefit those patients who do not require vasopressor or inotropic support to wean from CPB, as the use of vasopressor and inotropic agents in this situation can be associated with unnecessary increased myocardial oxygen consumption. In our literature, other predictors of the need for vasopressor or inotropic agents with CPB separation include female sex, older age, low ejection fraction, cardiac enlargement, longer durations of CPB and ischemic time as well as the preoperative use of angiotensin converting enzyme inhibitor drugs.

Diastolic dysfunction (DD) has become increasingly important as one of the earliest markers of cardiac ischemia as well as a predictor of morbidity and mortality in heart failure patients. DD has been reported to be common in the population of patients presenting for coronary artery bypass grafting. DD can be evaluated in several ways. One of the least invasive but accurate measures of DD in through echocardiography utilizing doppler spectral analysis. This methodology is readily available in the operating room, allowing for assessment of DD in the pre–CPB period. DD can be viewed as a continuum of severity from the least severe form – an abnormal relaxation pattern to a psuedonormalization pattern to the most severe – a restrictive pattern.

The authors postulated that the presence and severity of DD would predict the need for vasopressor or inotropic support with weaning the patient from CPB. Sixty–six heterogeneous patients (CABG, valve replacement and CABG with valve replacement) were studied before CPB using transesophageal echocardiography (TEE). Assessments of systolic and diastolic function were made. The anesthesiologists assigned to the care of the patient were blinded to the TEE myocardial functional assessments.

The authors found that DD was predictive of the need for vasoactive support. This was noted in both a univariate logistic regression (along with sex, age, systolic dysfunction, ischemic time and total CPB time) as well as a multivariate logistic regression (along with sex and total CPB time only). DD was associated with a four–fold increase in the need for inotropic or vasoactive drugs with weaning from CPB. A secondary finding was that DD was found in 30% of the 66 patients undergoing surgery requiring CPB.

The authors postulate that the presence of DD may indicate more ischemic myocardium and thus more muscle susceptible to reperfusion injury or an ischemic insult. The presence and extent of DD can thus influence whether to prophylactically administer vasoactive agents prior to weaning from CPB; the choice of which specific drug to use in order to best influence outcome is also possible.

Limitations of this study include 1) this particular assessment DD is dependent on filling conditions, and 2) the assessment of a heterogeneous population of patients in this study. Other echocardiographic methodologies for DD assessment, which are less dependent on filling conditions, may become increasingly utilized.

More importantly, this study shows us that knowing whether our patients have DD may affect how we care for them intraoperatively. Thus, we may have another tool to optimize the operative and perioperative care of patients needing CPB for cardiac surgery. Assessment of DD with TEE is an available and relatively easily utilized tool, which may improve perioperative morbidity in a set of patients most at risk.