According to a recent study by the American Health Association (AHA)-
Cardiac arrhythmias are a major cause of morbidity and mortality in heart disease and are the likely cause of more than a quarter of a million deaths annually in the United States alone.

What is Arrhythmia?

Arrhythmias are conditions in which electrical impulses are abnormally conducted through the heart, resulting in an altered heartbeat – muscle contraction – rhythm. These alterations to heartbeat rhythm can include changes in heart rate, irregularity of heartbeats, or fibrillation of the heart muscle. Arrhythmias are broken down into:

  • Slow heartbeat: Bradycardia.
  • Fast heartbeat: Tachycardia.
  • Irregular heartbeat: Fibrillation or flutter
  • Early heartbeat: premature contraction.

Complications associated with Arrhythmia

  • Stroke – Fibrillation (quivering) means that the heart is not pumping properly. This can cause blood to collect in pools and clots can form. If one of the clots dislodges it may travel to a brain artery, blocking it, and causing a stroke. Stroke can cause brain damage and can sometimes be fatal.
  • Heart failure – Prolonged tachycardia or bradycardia can result in the heart not pumping enough blood to the body and its organs – this is heart failure. Treatment can usually help improve this.

Why detection of Arrhythmia is important and how can it be avoided?

“It is a sad fact that in many cases where a person dies suddenly of cardiac arrhythmia, retrospective review of their case reveals that there had been previous warning of a potentially serious heart problem, such as chest pains, fainting, palpitations or convulsions,” says the cardiologist David Lefroy of Imperial College NHS Healthcare Trust. “Not infrequently, such people have seen a doctor for the problem or even been under the care of a cardiologist.”

The lack of urgency in diagnosing a disorder is causing avoidable loss of life and health. Of the 120,000 UK deaths from arrhythmia every year, 80 percent could be prevented, says the charity Arrhythmia Alliance. Thousands suffer a stroke or other serious health problems – or, at best, are left taking medication with serious side-effects.

According to the American Heart Association (AHA), more than 4 million Americans have arrhythmias and an estimated 638,000 hospital admissions are due to the condition.

Recent advancements in Detection of Arrhythmia

“Mobile applications and monitors are revolutionizing the way we interact with patients who have or are at risk for arrhythmias. Over the past decade, major advances have occurred in both external and implantable monitoring devices. External ambulatory monitors have decreased in size and complexity while the storage capacity has increased. Self-contained wireless patch monitors that self-adhere to the patient’s chest are capable of recording and storing single-lead ECG recordings for up to 30 days.

Improvements in size, ease of use, functionality, accuracy, and longevity over the next decade will spur on the current movement to extend the use of these monitors beyond traditional diagnostic indications to screening tools in targeted populations.

The automatic monitoring and reporting that this technology provides have reduced the frequency of office visits and allowed more rapid diagnosis and treatment of arrhythmias and device malfunctions. Physicians are notified quickly of actionable events rather than having to wait for patients to be seen at scheduled office visits or to present urgently when the arrhythmia reaches the threshold to cause symptoms. In large-scale studies, the use of remote monitoring has been associated with improvements in survival and a decrease in adverse outcomes such as hospitalizations.”
-Circulation, AHA Journal, Volume 133, Issue 25

“Echocardiography plays a significant role in the management of patients with Supraventricular Arrhythmias (SVT). SVT is observed in 10-20% of these patients and is associated with increased risk of stroke and sudden cardiac death. The most common SVTs are atrial arrhythmias in ASD and atrial flutter in patients who underwent the Fontan and Fallot procedures. Evaluation for the type of structural disease, ventricular dysfunction, and presence of atrial thrombus can be performed by echocardiography to determine the timing and the strategy of the management.
In a study of 154 Atrial Fibrillation (AF) patients treated with Radio Frequency Catheter Ablation (RFCA), Montserrat et al. showed that the combination of clinical data and LA function evaluated by 3D echocardiography predicts the successful cardioversion of AF in sinus rhythm after a first ablation procedure for AF. Left atrial strain determined by two- or three-dimensional speckle tracking echocardiography is another powerful predictor of atrial fibrillation recurrence after catheter ablation according to two recent studies.”
-Hellenic Journal of Cardiology,
Published online- December 5, 2017

Electrocardiograph for the Detection of Arrhythmia abnormalities

The most effective way to diagnose an arrhythmia is with an electrical recording of your heart rhythm called an electrocardiogram (ECG). An ECG test traces changes in the voltage that is detectable in the course of a heartbeat. It’s the most useful record of heart function and the best way to reveal the cause of irregular heartbeats. If an arrhythmia is suspected but doesn’t show up on ECG, you can have a 24-hour or even a seven-day ECG, using equipment put in place in the hospital and worn at home. An exercise ECG, taken while you’re on a treadmill, shows how your heart responds to strenuous exercise. An echocardiogram scan can pick up structural abnormalities in the heart.

According to a recent paper published by International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering-
Computer-aided feature extraction and analysis of ECG signal for disease diagnosis has become the necessity to take care of a large number of cardiac patients efficiently and effectively. The QRS complex is the most prominent feature and its accurate detection forms the basis of extraction of other features and parameters from the ECG signal. A good amount of research work has been carried out during the last five decades for the accurate and reliable detection of the QRS segment in the ECG signal.

The QRS detection algorithms developed so far can be broadly placed into four categories: (i) syntactic approach (ii) non-syntactic approach (iii) hybrid approach and (iv) transformative approach.

A. Syntactic Approach

The syntactic approach is basically pattern recognition based QRS detection techniques. The ECG signal is first reduced into a set of elementary patterns like peaks, durations, slopes, interwave segments and thereafter use rule-based grammar. The signal is represented as a composite entity of peaks, duration, slopes and inters wave segments. These patterns are then used to detect the QRS complexes in the ECG signal.

B.Non-syntactic Approach

Non-syntactic type is the most widely used class of ECG feature extraction techniques. In this class, we find the use of amplitude, slope and threshold limit as well as the use of different filters, mathematical functions and models to detect abnormalities.

C.Hybrid Approach

In the hybrid approach, the syntactic and non-syntactic approaches are combined to detect the QRS complex.

D.Transformative Approach

Transformative Techniques, namely Fourier Transform, Cosine Transform, Pole –zero Transform, Differentiator Transform, Hilbert Transform and Wavelet Transform are being used for the QRS detection. The use of these transforms on ECG signal helps to characterize the signal into energy, slope, or spike spectra which are further used to detect abnormalities in the heart.