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Ectopic Beats, Activity Effects and Heart Rate Turbulence Gari Clifford Harvard-MIT Division of Health Sciences & Technology.

Published byCason Lamb Modified over 4 years ago


Presentation on theme: "Ectopic Beats, Activity Effects and Heart Rate Turbulence Gari Clifford Harvard-MIT Division of Health Sciences & Technology."— Presentation transcript:

1 Ectopic Beats, Activity Effects and Heart Rate Turbulence Gari Clifford email@example.com www.mit.edu/~gari/ Harvard-MIT Division of Health Sciences & Technology HRV 2006

2 Outline Overview of Cardiovascular Nonstationarity Activity/Sleep-Wake Effects Ectopy –HR Turbulence –QT Turbulence

3 Overview: Dealing with Discontinuities RR tachogram unevenly sampled - Resampling introduces errors. Spectral methods assume linear, stationary processes RR tachogram is nonstationary; ectopy, artefact or intrinsic cardiovascular changes HRV is a function of both physical and mental activity Artefacts and ectopy can be removed, but this is also information Artefact is an indicator of state change Ectopy affects the RR tachogram – Heart Rate Turbulence

4 Cardiovascular Nonstationarity Tachogram has many states with similar means or variances Length of state varies minutes (weakly stationary) Movements between states have brief accelerations in RR interval new mean and/or variance. Dont apply HRV methods blindly - Must control for state! Time ( 40 mins ) HRi

5 HRV depends on activity HRV changes significantly in different sleep states Adapted from: Otzenberger et al.Dynamic heart rate variability: a tool for exploring sympathovagal balance … in sleep Am J Physiol Heart Circ Physiol 275: H946-H950, 1998. Awake Control for state when applying HRV methods! Light Sleep Deep Sleep Dream Sleep Control for state when applying HRV methods!

6 Changes due to ectopy Data courtesy of PhysioNet; http://www.physionet.org

7 Heart Rate Turbulence SA node response to ectopic beat; short HR acceleration then deceleration. Maintain BP; rapid parasympathetic withdrawal? Then parasympathetic innervation baseline http://www.h-r-t.org/hrt/en/hrtdemo_js.html Credit: R. Schneider: http://www.librasch.org/

8 Heart Rate Turbulence Ectopic beats disturb RR tachogram stationarity Disturbance lasts 10 - 20 beats HRT quantifies this disturbance using 2 metrics: –TO: Turbulence Onset –TS: Turbulence Slope

9 TS/TO: Turbulence Onset/Slope Credit: Bauer A, Barthel P, Schneider R, Schmidt G. Dynamics of Heart Rate Turbulence. Circulation 2001b; Vol. 104; No. 17; Supplement; II-339, 1622.

10 Turbulence Onset (+ index intervals after ectopic, - index before) Percentage difference between mean of each pair of NN intervals on either side of ectopic pair Must average the TO over >> 10 ectopics

11 TS: Turbulence Slope Find steepest slope for each possible sequence of 5 consecutive normal intervals from RR +2 RR +16 Usually average 10- 20 time series first then calculate one TS on the average time series! Outlier Rejection Important: (See Notes) Clifford, G.D., ECG Statistics, Noise, Artefacts and Missing Data, Chapter 3 in Advanced methods and tools for ECG data Analysis, Clifford,et al (Eds), Artech House,2006.

12 Examples Figure Credit: Mäkikallio et al., Eur. Heart J., April 2005; 26: Run: http://www.librasch.org/hrt/en/hrtdemo_java.html

13 Normal Response TO > 0 and TS > 2.5 are normal (a healthy response to PVCs is a strong sinus acceleration followed by a rapid deceleration) An independent predictor of late mortality after acute MI [Schmidt 1999, Ghuran 2002, Wichterle 2004, Watanabe 2005, Baur 2006] Abnormal HRT Predicts Initiation of Ventricular Arrhythmias [Iwasa 2005] HRT indices appear to correlate better with EF than SDNN in Chagas disease [Tundo2005] HRT Predicts Cardiac Death in Patients Undergoing CABG [Cygankiewicz 2003] Prognostic Marker in Patients with Chronic Heart Failure [Kayama 2002] Risk Predictors in Patients With Diabetes Mellitus [Barthel 2002] Decreased HRT in patients with diabetes mellitus [Barthel 2000]

14 Nonstationarity Example: QT Hysteresis QT is HR-dependent QT interval = depolarization + repolarization QTc: marker of arrhythmias & potential predictor of mortality QTc = QT/RR n n = ½,

15 Nonstationarity Example: QT Hysteresis

16 QT turbulence -QT-interval turbulence occurs in association with - QT-interval turbulence occurs in association with HRT following induced ventricular or atrial ectopy HRT following induced ventricular or atrial ectopy Replace NN intervals by QT intervals - Replace NN intervals by QT intervals - QT TO but not TS reported to be useful (so far) - Other metrics exist; Its a nascent field Patients with ischemic VT and LV dysfunction exhibited significantly lower QT TO values than those with nonischemic VT and normal LV function. Savelieva,I., Wichterle,D., and Camm, J.A., QT-Interval Turbulence Induced by Atrial and Ventricular Extrastimuli in Patients with Ventricular Tachycardia, PACE, 28, s1, S187-S192, 2005,

17 Recap / Conclusions Nonstationarities important both as confounders and information conveyors Dont just ignore/remove them HRT is interesting approach to extracting information from very short nonstationary segments of data Acknowledgements: Many, many thanks to Raphael Schneider! See www.h-r-t.org for more information and software.www.h-r-t.org
 ECG ROUNDS Navpreet Sahsi. HEART TRANSPLANTATION Pediatric Recipients ISHLT 2007 J Heart Lung Transplant 2007;26: © 2010, American Heart Association. All rights reserved. A Validated Risk Score for In-hospital Mortality in Patients with Heart Failure from the American. Texas Tech University Health Sciences Center Bronze Level Electrocardiography Conduction System of the Heart CMR of Non-ischemic Dilated and Restrictive Cardiomyopathies Exercise Stress Electrocardiography Cardiovascular Disaster in Hemodialysis patients Predictors of Early Cardiovascular Disease in Children with CKD Advanced ECG’s for MLA’s Heart Rate Variability in Heart Failure and Sudden Death Phyllis K Stein, Ph.D. Heart Rate Variability Laboratory Electrical Activity of the Heart Topic Number 2. Introduction ✦ What’s really happening when the heart is stimulated or where does the “electro” in electrocardiography.