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Myocardial Dysfunction in Severe Sepsis

Myocardial Dysfunction in Severe Sepsis

ARTICLE REVIEW

In their original article Clinical spectrum, frequency and significance of myocardial dysfunction in severe sepsis and septic shock (Mayo ClinProc, 2012), Pulido et al.found that myocardial dysfunction in patients with severe sepsis and septic shock has a wide spectrum, but is not associated with increased 30-day or 1-year mortality.

Several works have already described different types of myocardial dysfunction in sepsis including left ventricular (LV) systolic and diastolic dysfunction and right ventricular (RV) dysfunction. All these types of myocardial dysfunction can be present in isolation or combination and can be reversible on resolution of critical illness. Rejecting the current definition of myocardial dysfunction in sepsis as the mere reduction of LV ejection fraction (LVEF) under 45%-50% value, authors sought to thoroughly characterise this phenomenon by describing the different types of myocardial impairment and by evaluating their impact on mortality.

One hundred six patients with severe sepsis or septic shock were prospectively studied by trans-thoracic echocardiography within 24 hours of admission to the intensive care unit. Systolic dysfunction was defined as mild (LVEF, 41%-50%), moderate (LVEF, 31%-40%), and severe (LVEF, <30%). Diastolic function evaluation was performed in accordance with the American Society of Echocardiography guidelines taking into account parameters obtained by pulsed-wave Doppler (peak mitral inflow E and A velocity waves, E/A ratio, E-wave deceleration time), by tissue-Doppler imaging (TDI) at both septal and lateral mitral origins (the systolic s’ and the diastolic e’ and a’ peak velocities, e’/a’ ratio, E/e’ ratio). RV function was evaluated by a multimodal approach using TDI (lateral tricuspid annulus peak systolic velocity) in association with the relative RV-to-LV size, motion of the RV wall and expert evaluation.

The frequency of myocardial dysfunction in patients with severe sepsis or septic shock was 64% (). Left ventricular diastolic dysfunction was present in 39 patients (37%), LV systolic dysfunction in 29 (27%), and RV dysfunction in 33 (31%). Several patients had a combination of systolic and diastolic dysfunction, as well as right and left ventricular dysfunction. The 30-day and 1-year mortality rates were 36% and 57%, respectively. There was no difference in mortality between patients with normal myocardial function and those with left, right, or any ventricular dysfunction.

Myocardial dysfunction is frequent in patients with severe sepsis and septic shock, but its characterisation is still difficult because of many clinical and technical concerns:

-  regarding LV systolic function, a LVEF > 45-50% is classically required to define a systolic dysfunction; nevertheless, from a physiological point of view, the ejection phase of the cardiac cycle does not represent the whole systole and the heart should be considered a “muscular” rather than a mere “hemodynamic” pump. When considering the heart as a “muscular” pump, other parameters need to be evaluated (e.g. those related to the isovolumic contraction phase and to the LV synchronicity).

-  regarding LV diastolic function, the publication of diagnostic guidelines by the American Society of Echocardiography in 2009 standardized data interpretation; nevertheless, normal cut-off values for each parameter are still required in relation to age, gender, racial origin and associated pathologies.

-  regarding RV function, its evaluation remains a matter of debate, and the particular RV anatomy still makes it difficult to thoroughly describe its performance.

-  the number of patients enrolled in almost all papers about this subject does not allow a thorough categorisation of myocardial dysfunction during sepsis and septic shock.

-  because of the dynamic nature of sepsis, variability in host response, and underlying disease, as well as the complex interaction between the cardiovascular and respiratory systems, the evaluation of myocardial dysfunction is limited to isolated “snapshots” in time during the disease process and treatment.

All these concerns could explain the discrepant results found in the literature and call for more large scale studies in order to deepen out understanding of septic myocardiopathy.

This article review has been prepared and submitted by Mario Rienzo of ESICM’s Cardiovascular Dynamics Section.

References

Pulido JN, Afessa B, Masaki M, Yuasa T, Gillespie S, Herasevich V, Brown DR, Oh JK.Clinical spectrum, frequency, and significance of myocardial dysfunction in severe sepsis and septic shock. Mayo Clin Proc. 2012 Jul;87(7):620-8. doi: 10.1016/j.mayocp.201   
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