International Journal of Scientific & Engineering Research, Volume 5, Issue 7, July-2014 530

ISSN 2229-5518

Real time Data Stream Mining Approach to

Arrhythmia Prediction

Rashmi K.Sonule, Dipti D.patil

Abstract— Recent data mining techniques are modeled to handle stream data by applying online and incremental approach where concept changes in dataset are learned efficiently. Streaming random forests algorithm is an extension of Breiman’s random forests algorithm which handles online and incremental stream data. Streaming random forests adapts ensemble framework where classification is based on majority of tree votes. The work proposed in this paper mainly deals with construction of an efficient arrhythmia prediction system

using streaming random forests algorithm for classification of three arrhythmia types. We applied streaming random forests algorithm on arrhythmia dataset obtained from physionet website and found that its accuracy is highly acceptable.

Index Terms— Arrhythmia Prediction, Concept drift, Data stream mining, ECG, ECG signal preprocessing, Feature extraction, Streaming random forests.

1 INTRODUCTION

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ardiovascular diseases remain a major threat to human life due to rapid changes in life style. Arrhtyhmia, a type of heart disease caused because of irregular rhythms or
rate of heartbeats.Arrhythmia causes the heart to provide in- sufficient supply of blood to other organs which can cause damage to the brain or other organ.Atrial Fibrillation, prema- ture Ventricular Contractions, ventricular Fibrillations, heart blocks etc are certain types of arrhythmia.
Continuous ,real world ,changing ,infinite data obtained from semi-strucutred and non-structured databases, internet
,multimedia databases etc is termed as data stream .Data stream mining refers to informational structure extraction as models and patterns from continuous data streams[5]. To deal with the high arrival rate of records, the data stream mining algorithms should be online and incremental.This gives a chal- lenging phase in desiging stream algorithms since the infor- mation need to extract from single pass over records. Com- pared to Stream Classification algorithms, Mainstream Classi- fication algorithms come up with three phases: Training, Test- ing and Deployment [4].Stream Classification Algorithms pro- cesses single stream of data which creates a need for interleav- ing all the three phases.ECG pathologies generate vast data which yields various features that plays a major role in better detection and classification of cardiac diseases.
This paper presents an arrhythmia prediction system using Streaming Random Forests algorithm for classification of ar- rhythmia into three different types.The system first preprocess- es the ECG signals for normalizing them.The extracted features

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• Rashmi Sonule is currently pursuing master of Engineering in Information Technology from MITCOE, Pune affiliated to Pune University. E-mail: rashmisonule_2007@yahoo.co.in

• Dr.Dipti D.Patil is currently working as an Associate professor in Com- puter Engineering Department, MITCOE, Pune affiliated to Pune Univer- sity. E-mail: dipti.patil@mitcoe.edu.in

2 RELATED WORK

The increase in the number of patients in intensive care units and their continuous observations call for the need of auto- mated arrhythmia detection and prediction.Several researches and studies have emerged techniques to address this problem and much more are currently in practices. These techniques adapt the criteria of transforming mostly qualitative diagnos- tic feature into a more quantitative signal feature classification task.The ANFIS classfier uses as input the four statistical pa- rametes calculated from ECG signals for cardiac arrhythmia classification [3].The ANFIS classifier combines the best fea- tures obtained from fuzzy systems and neural networks.In [6] the Artifical Neural Network(ANN) based on feed forward back propagation with momentum used for classification of arrhythmia.The four parameters considered for classification are obtained from RR interval and the QRS complex .A knowledge-based method for arrhythmic beat classification and arrhythmic episode detection and classification using RR- interval signal is proposed in [7].The beat classification algo- rithm and deterministic automaton used for classification of four categories of beat and six rhythm types respective- ly.Author Mahesh et.al focused on the heart rate and Heart Rate Variability (HRV) for detecting cardiac abnormali- ties.Classification has been done using the combination of linear ,non-linear measures with the help of three classifiers
,Random Forests,Multilayer Perceptron Neural Network and
Logistic Model Tree.
The detection of abnormal cardiac rhythms and automatic
discrimination from the normal heart activity become an im-
portant task in clinical reasons. Several techniques are based
on the detection of a single arrhythmia type and its discrimi-
nation from normal sinus rhythm or the discrimination be-
tween two different types of arrhythmia.
are given as input to the classification alogirthm to form the classification rules which help to predict the type of arrhythmia.

International Journal of Scientific & Engineering Research, Volume 5, Issue 7, July-2014 531

ISSN 2229-5518

3 REAL TIME DATA STREAM MINING

Continuous, endless, ordered sequence of data is often termed as Stream. Existing data mining algorithms are uable to extract knowledge from stream datasets. Data stream mining algo- rithms have constraints such as online result generation, han- dling fast arrival rate of records, efficient concept drift adap- tion etc.The aim of many stream mining applications is to pre- dict the class or label of new instances provided knowledge of previous seen, known class membership or values of previous instances in the data stream.To cope with online learning, real time approaches often the concept changes, incremental learn- ing techniques are applied .Decision tree learning is widely adapted classification method for stream mining.VFDT(Very Fast Decision Tree )able to learn from abundant data within practical time and memory constraints[10].CVFDT(Concept- adapting Very Fast Decision Tree Learner) is an extension of VFDT which maintains VFDT’s speed and accuracy with add- ed ability to detect and respond changes in example generat- ing process[11].Both the algorithms lack the ability of perform- ing classification in real-time.

4 STREAMING RANDOM FORESTS [1]

Streaming Random Forests is a combination of techniques used for building decision trees and attribute selection tech- niques of Random Forests.The original Random Forests Algo- rithm proposed by Breiman [2] uses bootstrap sample of data for growing multiple decision trees.The majority of votes from all trees contribute for classification task.In general, random forests are similar to ensemble of binary decision trees.In con- trast to the standard random forests algorithm the streaming version does not possess the facility of making multiple passes over data.Seperate block of labeled records is required for building each tree.Due to this more labeled data is required for building a set of trees.To contribute towards decision of any node every labeled record is routed to an appropriate node of tree under tree building procedure.Whenever a new labeled record is arrived it is routed down the current tree,depending on its attribute values and inequalities of in- ternal nodes [1].For selection of best attribute and splitting point the Gini Index test[9] and Hoeffding bound criterion[10] need to be satisfied.The transformation of frontier node into internal node is based on the inequality of attribute and split point.Whenever records accumulated at a node resemble par- ticular class the node is converted into leaf node.The basic tree building procedure in streaming random forests algorithm with different tree building parameters is shown in Fig 1.

5 PROPOSED WORK

Though there are number of diseases, it has been observed and bring forth by world health organization that the death rate due to cardiovascular diseases remains high.To aid in the quality of better health care it is advisory that the patient need to be continuously monitored and the automatic diagnosis and speedy recovery should be achieved.The system architecture shown in Fig 2 takes the ECG signal as an input and predicts the arrhythmia types as an output.

Procedure BuildTree

/*grow tree*/

while more data records in the tree window

read a new record
pass it down the tree

if it reaches a frontier node

if first record at this node

randomly choose M attributes
find intervals for each of the M attributes
update counters
if node has seen nmin records

if Hoeffding bounds test is satisfied

save node split attribute
save corresponding split value

if no more records in the node window

if node records are mostly from one class

mark it as leaf node
assign majority class to node

else

save best split attribute seen so far
save corresponding split value
end while
/* prune tree */

while more frontier nodes

if node has records arrive at it

mark it as leaf node
assign majority class to it

else /* node has zero records */

if sibling node is frontier with no records

calculate purities of both sibling nodes

if purities < pre-defined threshold

prune both nodes
mark parent node as a leaf
assign majority class to it

else

mark node as leaf node
assign dominant class to it

end while

end

Fig 1.Tree Building procedure in Streaming Random
Forests [1]
ECG is a recommended tool for cardiac status analysis. With diseases classified on the basis of intervals between the vari- ous segments (PQRST) of ECG signal, this gives us an optimal assessment. Arrhythmia Prediction system provides an inter- face which would not affect the normal life cycle of a Heart Patient. This is done by providing on the go examination fea- tures with the use of system, the accuracy and complexity be- ing taken into consideration. The ECG signal which is taken as an input is passed through various stages like Feature Extrac- tion, Preprocessing, Classification of features and the For- mation of rules using Streaming random forests algorithm. The system consists of two parts, online and offline processing

International Journal of Scientific & Engineering Research, Volume 5, Issue 7, July-2014 532

ISSN 2229-5518

of data. The offline mode consist of training dataset formed using collections of patient’s ECG records with three arrhyth- mia types .In online mode the continuous ECG signal is taken as input and it is passed to pre-processing module. In this module the noise is removed from ECG signal, then the fil- tered ECG signal is given to feature extraction module where all time domain features of signal are extracted like R-R inter- val, Root Mean Square Successive Difference (RMSSD), Standard Deviation (SDNN) etc [3]. The data stream mining algorithm uses these calculated features to create rule database which is further used for classification task of new unlabelled records.
Fig 3. Arrhythmia Predicted as type PVC

TABLE 1

TESTING RESULTS ON MIT-BIH ARRHYTHMIA DATASET

Fig 2. Proposed System Architecture for arrhythmia pre- diction

6 ARRHYTHMIA PREDICTION

The system is able to detect three types of arrhythmia namely PVC, AF and NSR.The ECG signals for training of classification algorithm were obtained from the MIT-BIH Atrial Fibrillation Database, MIT-BIH normal sinus rhythm database and MIT- BIH supraventricular Arrhythmia database. For testing purpose the MIT-BIH Arrhythmia database is used [12].The range of four statistical parameters calculated as a result of training da- taset is further used for classification of new unlabeled rec- ords.Figure 3 shows the schematic of the arrhythmia prediction performed .
Table 1 shows the testing result of streaming random forests on MIT-BIH arrhythmia dataset for AF, PVC and NSR diseases.

International Journal of Scientific & Engineering Research, Volume 5, Issue 7, July-2014 533

ISSN 2229-5518

7 CONCLUSION

Computerised detection and classification of ECG signals is gaining a worldwide attention due to quick diagnosis and preventive actions. The availability of a good classifier for classifying the arrhythmia types in a patient creates an oppor- tunity for future development that implements the results of this research to work in the form of decision support system. The proposed and developed system performs analysis of var- ious ECG signals and predicts the type of arrhythmia. The system helps an individual by evaluating his or her risk levels in terms of arrhythmia symptoms and will alert the patient as well as the physician from the problems one can suffer. The system is developed in such a way that it can handle all ECG signals whether normal or abnormal. The streaming random forests algorithm works on the extracted features efficiently for determining the type of arrhythmia present in a patient.

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[14] Sheng Hu, HongxingWei, Youdong Chen, and Jindong Tan, “A real- time cardiac arrhythmia classification system with wearable sensor network,” Sensors 2012, 12, 12844-12869; doi: 10.3390/s120912844.

[15] Dipti D.Patil, Dhanashri Patil,Sharlin Pandharpatte,Ruta

Dhekane,Trupti Mohol,and Dr.V.M.Wadhai,”Intelligent Arrhythmia Diagnostic System,”IJSCI International Journal of Computer Science Issues,Vol.9,Issue 6,No 1,November 2012.

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