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Heart rate turbulence - state of the art



The first presenter, Dr D Wichterle (Prague, CZ), described the physiological processes that induce the Heart Rate Turbulence (HRT) pattern. Heart rate turbulence is produced by the complex interplay of parasympathetic and sympathetic responses to the initial mechanical trigger. Hemodynamically inefficient ventricular contraction together with compensatory pause is responsible for baroreceptor deafferentation causing the transient loss of vagal efferent activity and early heart rate acceleration.
 
Initial hemodynamic event also triggers bursts of sympathetic nerve activity producing delayed transient vasoconstriction and relative hypertension and, consequently, vagally mediated heart rate deceleration with transient relative bradycardia. Intact vagal function is sufficient for maximum early heart rate acceleration. Physiological responses of both the sympathetic and parasympathetic systems are necessary for fully expressed late heart rate deceleration.

The second presentation by Dr A Bauer (Tubingen, Germany) dealt with the technical aspects of HRT measurement. HRT assessment requires 5 or more sinus intervals before and 15 or more sinus intervals after a ventricular premature complex (VPC). Interpolated VPCs have to be excluded by certain algorithms. Turbulence Onset and Turbulence Slope must be derived from averaged ECG sequences.

Pr Federico Lombardi (Milan, Italy) described the clinical potential of HRT. Identification of patients at risk is a major clinical challenge for high incidence of sudden cardiac death in post-myocardial infarction and heart failure patients. Abnormal HRT testing has been associated with increased mortality after myocardial infarction. New prospective studies have confirmed the independent prognostic value of abnormal HRT in patients with either depressed or preserved LVEF after myocardial infarction and in patients with dilated cardiomyopathy. The high predictive value of HRT has been proven in patients with optimal medical therapy and, in the case of myocardial infarction, with almost 90% of mechanical revascularisation.

Dr Philippe Chevalier (Lyon, FR) spoke about pharmacologic modulation of HRT. He reported on first studies dealing with vagomimetic drugs, alpha and beta-blockers, and renin-angiotensin system inhibitors. He stressed that other receptors such as mechanical stretch receptors could be future targets of pharmacological interventions. He suggested that short term pacing studies may be useful for pharmacological evaluation of new drugs.

References


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SessionTitle:

Heart rate turbulence - state of the art

Notes to editor


This congress report accompanies a presentation given at the ESC Congress 2009. Written by the author himself/herself, this report does not necessarily reflect the opinion of the European Society of Cardiology.

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.