ABSTRACT: Heart Defects are immensely threatful to human beings and can causedeath.
Improvements in diagnosis and treatment tools are welcome by the medicalcommunity and have proven to be one of the most useful diagnostic tools forheart patients, one of it to be mentioned would be the Electrocardiogram (ECG),which operates by measuring the electrical signals emitted by the heart throughelectrodes and records the electrical activity of the heart in exquisitedetail. The automatic ECG processing and classi?cation is an emerging tool forthe cardiologists in medical diagnosis for e?ective treatment. Traditionaltechnique of visual analysis of ECG is complicated for doctors, time consumingand requires expertise. Hence, Computer based classi?cation and detection ofdiseases can be immensely useful in diagnostics.
This project has been inspiredby the need to ?nd an e?cient method for ECG Signal Analysis and Classificationwhich is simple yet has good accuracy and less computation time. It deals withthe study and analysis of ECG signal processing by means of MATLAB toole?ectively for classi?cation and detection of heart defects using Lead-IICon?guration. Study of ECG signal includes reading and plotting of the ECGsignal, acquisition of real time ECG data, ECG signal ?ltering and processing,feature extraction and detection of certain parameters, decoding, comparison,classification of the required features.
This enormous amount of informationcan be stored in the memory for further correspondence. In this thesis, we ?rst?nd out the characteristics to classify a Normal ECG and then pass any randomsignal to check whether the features or the values determined fall within thespeci?ed range with the ones characterized to be a normal ECG. If it does, thenwe classify it as Normal ECG else we classify it as an Abnormal ECG usingLead-II Configuration. KEYWORDS:Electrocardiogram (ECG), Lead-II Con?guration, ECG Processing and Classification,Heart Defects, Matlab. I. INTRODUCTIONHeart is known to be the most significant organ ofthe human body that beats in rhythm to pump the blood in circulation throughthe body which results in making the action potentials responsible for themechanical events within the heart that generates a certain sequence ofelectrical events. Due to contraction and relaxation of the muscle tissue ofthe heart, electrical activation begins by the movements of ions whichconstitute current throughout the body giving rise to potential differences inmillivolts.
An ECG or EKG (Electrocardiogram) records thesepotential differences’ using electrodes attached to the surface of the skin andmeasures the electrical activity of the heart recorded by a device external tothe body over the amount of time. It has been known since 1856 that the heart muscle produceselectrical activity and subsequently that it can be measured to provide functionalstatus and diagnostic information about the condition of an individual’sheart. Since the required measurementsare very low in magnitude, noise can have a great impact on measurements.The ECG analysis is performed by using signal processing.Signal processing being the enabling technology encompasses the fundamentaltheory, applications, algorithms, and implementations of processing ortransferring information contained in many di?erent physical, symbolic orabstract formats broadly designated as signals.
The modi?cation and processing is used to maximizethe details of information extraction and further analysis. The ECG techniqueis implemented with software to perform a various operations like reading,decoding and recording a data depending on the computing platforms. Then thewaveform is used to ?nd the rate of heart beat, heart rate, heart ratevariability and any disease which are a?ected by the heart. II. HISTORICAL BACKGROUND OF ECGAND CLINICAL INTERPRETATION OF ECG PARAMETERS ECGor EKG is basically an abbreviation for theword electrocardiogram (derived from the Greek electro for electric, cardio forheart, and graph for “to write”) and the German word electrocardiogram.In1901 the device used by Willem Einthoven he invented while working in Leiden, Netherlands,used the string galvanometer proved to be much more sensitive than both thecapillary electrometer Waller used and the string galvanometer that had beeninvented separately in 1897 by the French engineer Clement Ader. EarlierEinthoven’s subjects would immerse each of their limbs into containers of saltsolutions from which the ECG was recorded. The letters assigned by Einthoven tothe various deflections that described the electrocardiographic features of a numberof cardiovascular disorders were P, Q, R, S, and T.
Einthoven was awarded theNobel Prize in Medicine for his discovery in 1924. Though the basic principlesof that era are still in use today, over the years many advances in electrocardiographyhave been made. Fig1: An ECG Graph Paper Measurement The study of the ECG signal is extensively used foridentification and analysis of irregularities and heart diseases. Each portionof the heartbeat produces a totally different deflection on the ECG thatrepresents a realistic and graphic record of the direction and magnitude of theelectrical activity of the heart. The sinus (Sino-atrial node) node located near theentrance of the superior vena cava vein, acts as a generator of the sinusrhythm that produces the heart frequency at about 60-100 cycles per minute.This activation is then propagated to the right and left atria muscle tissues. Thereis a delay at the atrioventricular node, to allow the ventricles to fill withblood from atrial contraction.
This is then followed by the depolarization propagatingto the ventricles through the Bundle of His and spreads along the Purkinjefibers. This in turn activates the ventricles that contract and pump blood tothe aorta and to the rest of the body. Finally, depolarization occurs followedby repolarization and this cycle is repeated. A Normal ECG waveform tracing (in Lead-II) has acharacteristic shape and features as mentioned in the table.Fig 2:A General ECG WaveformThe table 1 shows the ECG features and descriptions.
Table 1:ECG Features and their Description FEATURE DESCRIPTION P WAVE P-waves represent atrial depolarization. P-R SEGMENT OR PQ SEGMENT The PR or PQ segment is the flat, usually isoelectric segment between the end of the P wave and the start of the QRS complex. This segment represents the time the impulse takes to reach the ventricles from the sinus node. P-R INTERVAL OR PQ INTERVAL The time taken for electrical activity to move between the atria and ventricles is represented by this interval. Q WAVE The normal Q wave represents septal depolarization and is any initial downward deflection after the P wave. R WAVE The R wave represents early ventricular depolarisation and is normally the easiest waveform to identify on the ECG. R-R INTERVAL The RR-interval begins at the peak of one R wave and ends at the peak of the next R wave and represents the time between two QRS complexes.
S WAVE The first negative deflection after the R wave represents the S wave indicating the late ventricular depolarization. QRS COMPLEX The depolarization of the ventricles is represented by the QRS Complex. QT INTERVAL It represents the time taken for the ventricles to depolarize and then repolarize. ST SEGMENT The isoelectric line that represents the time between depolarization and repolarization of the ventricles (i.e. contraction) represents the ST segment. J-POINT The J point is the junction between the termination of the QRS complex and the beginning of the ST segment. T WAVE.
The T-wave represents ventricular repolarization. T-P INTERVAL The isoelectric interval on the electrocardiogram (ECG) is TP segment that represents the time when the heart muscle cells are electrically silent. T-Q INTERVAL Termed as the diastolic interval through the ECG. U WAVE U waves represent re-polarization of the Purkinje fibers that indicates the last remnants of the ventricular repolarization. Generally it is 0.05mV and has duration of 0.1s.
III. THE LEAD-IICONFIGURATIONUnder the expert guidance ofthe doctors and after lots of literature review, it was seen that Lead II isthe most preferred monitoring lead of choice for continuous ECG monitoring.Mostly monitors show one lead at a time, so it is necessary to choose a leadthat gives as much information as possible. The most commonly used lead is LeadII which measures the potential di?erence between the right arm and left legelectrode.
Since its appearance in 1910 with Willem Einthoven’s invention ofthe electrocardiograph, Lead II has traditionally been the most commonly usedmonitoring lead.Fig 3: The Einthoven’sTriangleParamedics are trained how to interpret rhythms inlead II and have traditional exams wherein they have established a paradigm oflead II monitoring in patients. The placement of electrodes for Lead-IIcon?guration is located near the apex of the heart due to its best view.
It isthe most useful lead for detecting cardiac arrhythmias as it lies close to thecardiac axis (the overall direction of electrical movement) and allows the bestview of P and R waves. IV. ARRHYTHMIAAND IRREGULATIES OF THE HEARTIn the morphology of ECG signal where the normalrhythm of the heart represents no disease or disorder is called Normal sinusrhythm (NSR). ECG arrhythmia can be defined as a condition in which theelectrical activity of the heart is irregular and can cause heartbeat to beslow or fast.
The heart rate of NSR is generally defined by 60 to 100 beats perminute in a normal resting person.Arrhythmia could be of many types and can beclassified with respect to three factors:· Regularity (Regularly, Irregular and Irregularly, Irregular )· Rate (Abnormal Heart Rhythms)· Origin (Supraventricular and Ventricular)Ifa resting heart beats at a rate of 100 or more beats per minute in an averageadult, this would represent abnormal rapid beating of the heart defined as Tachycardiaresulting in a drop of pumping efficiency, adversely affecting perfusion.Bradycardia is defined as a resting heart rate below60 beats per minute and can adversely affect vital organs. Arrhythmia can take place in a healthy heart havingminimal consequence, but may also indicate a serious problem that leads tostroke or sudden cardiac death, scarring of heart tissue or change of heartstructure or heart blocks or premature beats.
Depending upon the type ofsymptom the arrhythmia would be classified.