Tachycardia in Septic Shock: Pathophysiological Implications and Pharmacological Treatment

Abstract

Heart rate is measured in every critically ill patient and high values often reflect the severity of underlying disease. Nevertheless, in clinical practice the pathophysiological implications of an increase in heart rate are often undervalued. The importance of elevated heart rate and its role in determining or contributing to cardiovascular diseases began to be recognized at the end of the 1970s. Nowadays, it is clear that tachycardia represents an independent risk factor for mortality and morbidity in several clinical conditions, including coronary artery disease, myocardial infarction, and congestive heart failure [1–7]. Furthermore, it has also been demonstrated that with respect to other cardiovascular factors, a high heart rate is the best predictor of mortality in different categories of patients [6]. Results of numerous large epidemiological trials confirm that an elevated heart rate not only represents a clinical sign of altered cardiac function but also contributes to cardiac dysfunction. Although the role of an elevated heart rate is well established and has clearly been linked to outcome in cardiology patients, the topic has gained less attention in septic patients. To date only a few small clinical studies have evaluated the relationship between increased heart rate and mortality in patients suffering from septic shock. However, the results of such studies strongly suggest that elevated heart rate is a risk factor for increased mortality, even in septic shock patients [8–10]. A reduction in heart rate could, therefore, improve outcomes for septic shock patients by lowering cardiac workload and improving diastolic coronary perfusion of the septic heart. Recently, the results from a monocenter trial that investigated the hemodynamic effects of reducing heart rate with the β-blocker esmolol in septic shock patients attracted the interest of critical care physicians [10]. The aim of this article is to provide an overview of the pathophysiology of sepsis-induced tachycardia and its implications in the clinical management of affected patients.