Cardiovascular wave analysis module for Scilab

Serge Steer

The heart : a pump

To o

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To the lungs

From the lungsO2

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sVentricular systole (contraction):● isovolumic contraction

➢ closes the atrioventricular valves ➢ opens sigmoid valves

● ejection

Ventricular diastole (relaxation)● isovolumic relaxation

➢ Opens the atrioventricular valves● filling

➢ Fast➢ Slow➢ Atrial systole

The heart : a regulated pump

Cellular oxygenation, in particular for brain

Long term control : hormones

Short term control : autonomic nervous system

Baroreceptor control loop: two antagonistic actions

- sympathetic = accelerator (fast)

- parasympathetic = inhibitor (slow)

Control also acts on arteries and veins

Sino atrial node

Cardiac electrical activity

The heart contraction is driven by electric depolarization of myocyte cells inducted by cardiac fibers.

Autonomous impulse generator

Cardiac fibers

Autonomic nervoussystem

Trans membrane voltage

DepolarizationSodium ions

Re polarizationPotassium ions Restauration of ionic balance

Cell membranes form electric dipoles

ECG

Electric dipoles generated by cells membranes of the heart produces an electrical potential at the surface of the thorax.

A set of electrodes, typically 3 to 10, are used to measure the electrical potential at different thorax locations.

The electrocardiogram (ECG) records voltage evolution deduced from the measured potentials

Cheap and non invasive

●

Typical ECG lead trace

P wave Atrial depolarization

QRS complex

Ventricular depolarization

T wave Ventricular repolarization

Applications of the ECG to cardiological diagnosis

● Arrhythmias detections● Disorders in the activation sequences● Increase in wall thickness or size of the atria

and ventricles ● Myocardial ischemia (coronary atherosclerosis)

and infarction ● ...

Heart rate and ECG morphology analysis provides cheap diagnostic elements

The Cardiovascular Wave Analysis module

Designed for – Long term ECG

– Multi-leads records

– Off line analysis

Consists of five classes of tools– Data acquisition

– Pretreatment

– Event detection

– Analysis

– Visualization

Data acquisitionSeveral file formats

● ISHNE Holter (Task Force standard)● TMS32 ( signals recorded using TMS ADC system and PortiLab)● WFDB (WaveForm DataBase used by Physionet)

Can be read and converted into a Scilab structure:

S=readTMS("ECG2.poly5",[25 27]);

viewECG(S(:,1))

Or converted to Scilab specific format (ecgs)

Easy for batch processing

Pretreatment● ECG subsampling● ECG FIR filtering ● Power line interference removal

● ECG detrending● Finding and removing outliers

viewECG([S(:,1) ECGSubstractPLI(S(:,1),50)])

Detections

● R peaks heart rate● T wave ends Q-T segment● All events

S=extractPartFromEcgsFile(“P5J0.ecgs",... 100,3000);S1=ECGDetrend(S);S1=ECGSubstractPLI(S1,50); L=ECGDetections(SynthesisECG(S1)); ECGShowDetections(S(:,1),L)

Analysis tools

Classical signal processing methods (heart rate spectral analysis)

Multichannel non stationary signal analysis

Baroreflex analysis (Arterial blood pressure effect on heart rate)

Complex demodulation (Breathing rate effect on heart rate)

Time frequency analysis

Time domain characteristics

Interactive toolsHRVAS (Heart Rate Variability Analysis System),

TimeFrequencyTool

The contribution of Scilab

● Signal processing and analysis● Data file handling● Graphics● Graphical user interface● Community● Free multi-plateforms software

Acknowledgments- Detection algorithms :

● Quighua Zhang (INRIA)

- Heart rate analysis algorithms: ● Alexandro Monti (INRIA)● John T. Ramshur (U. Menphis)

- Signal processing● D.E. Lake, J.R. Moorman and C. Hanqing● Wavelets :Christopher Torrence (Exelis), Gilbert. P. Compo (U. Colorado)● George B. Moody, Cambridge● Time Frequency toolbox: François Auger (CNRS), Holger Nahrstaedt (TU Berlin)

- Data● Physionet● François Cottin (U. Paris Sud)● Lisa Guigue ( INRIA)

- Testing● Claire Medigue (INRIA)● Lisa Guigue (INRIA)

- Atoms Module (http://atoms.scilab.org/toolboxes/CWA)● Dominique Callens (Scilab-Enterprises)

The end

Thanks