different degrees of parasympathetic activity on sinus node. Deceleration Capacity variants reflect different degrees of parasympathetic activity on sinus node. Arsenos1 P., Manis2 G. , Gatzoulis1 K.A. , Tousoulis1 D. 1First Department of Cardiology and Electrophysiology Laboratory, Hippokration General Hospital, National and Kapodistrian University of Athens, Athens, Greece. 2Department of Computer Science and Engineering, University of Ioannina, Ioannina. Greece.

Conflict of interest: None

Examination of Physiology of Heart Rate

Heart Rate physiology Generation of action potential in SAN Phase 4: The slope of depolarization is an important determinant of the rate of AP generation & heart rate max diastolic potential: -55mV Phase 0: inward Ca++ current Phase 1: there is generally no phase 1 in SAN Phase 2: brief plateau Phase 3: returns the cell to max diastolic repolarisation

Heart Rate physiology A Heart Rate physiology A. intrinsic regulation If pacemaker current establishes the slope of spontaneous diastolic depolarization Intrinsic heart rate in healthy individuals during complete autonomic blockade =100 bpm

Heart Rate physiology The autonomic nervous system at the SAN Sympathetic limp: nor-adr, adr acceleration of HR Parasympathetic limp: muscarinic actions of Ach deceleration of HR

Heart Rate physiology B. Extrinsic regulation physical activity response to mental activity sleep state through tonic activity of both limps of autonomic nervous system steepening the slope of spontaneous HR acceleration: diastolic depolarization Sympathetic limp: nor-adr, adr decrease in the slope of spontaneous HR deceleration: diastolic depolarization Vagus: muscarinic actions of Ach Arsenos 2016

Arsenos 2016

Background: Deceleration Capacity (DC) is an established total mortality predictor in post-MI patients.

Step 1. Definition of anchors. Step 2. Definition of segments. Step 3 Step 1. Definition of anchors Step 2. Definition of segments Step 3. Phase rectification. Step 4. Signal averaging. Step 5. Quantification of DC and AC.

Deceleration Capacity

DC=[x(0)+x(1) -x(-1)-x(-2) ]/4 Paradox negative values = acceleration! Arsenos Thesis 2013

Goal: We hypothesized that DCsgn and BBDC variants and the original DC method reflect each one, a different amount and analogy of ANS limps activity on sinus node. Rate dependence of these three DC variants was investigated.

Methods: Nineteen persons underwent Stress ECG test according Bruce protocol. Holter ECG recordings performed including pre-test resting ( 5 min), stress test (12 min), and recovery (10 min) periods. Heart rate, RR duration, DCorig, DCsgn, BBDC indices were extracted for three different heart rate periods: 1st : RR=400ms, 2nd : RR =600ms, 3rd : RR=900ms.

Results: DCorig (ms) DCsgn (ms) BBDC (ms) RR:400ms 1.5 2.5 3.9 3.6 4.0 4.7 RR:900ms 9.7 8.7

Conclusions: During fast heart rates (RR=400ms) BBDC presents the higher DC values. During lower heart rates (900ms) it is DCorg that present the higher DC values.

Conclusions: During fast heart rates (RR=400ms) BBDC presents the higher DC values. During lower heart rates (900ms) it is DCorg that present the higher DC values. DCorig (ms) DCsgn (ms) BBDC (ms) RR:400ms 1.5 2.5 3.9 RR:600ms 3.6 4.0 4.7 RR:900ms 9.7 8.7 3.9 9.7

Considering the vagus nerve function with fast achetylcholine release to the simus node and its short time effect on sinus node function (<400ms), BBDC with its beat to beat calculation algorithm, reflects probably in a higher analogy the vagus activity than DCorig and DCsgn.

DCorig and DCsgn variants probably reflect net parasympathetic and sympathetic effects on sinus node. BBDC is the nearest to parasympathetic activity DC variant.

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