AIMS current criteria for cardiac resynchronization therapy (CRT) are restricted to patients with a wide QRS complex (>120 ms). Overall, only 30% of heart failure patients demonstrate a wide QRS complex, leaving the majority of heart failure patients without this treatment option. However, patients with a narrow QRS complex exhibit left ventricular (LV) mechanical dyssynchrony, as assessed with...

conclusions right ventricular pacing increases the qt interval without increasing the jt interval. our results confirm that jtc, as an index of repolarization, is independent of ventricular depolarization. therefore, it can be applied for predicting qtc in patients with lbbb. results stimulation from the rva increased the qtc from 456.20 ± 38.63 ms to 530.67 ± 47.73 ms at a cl of 600 (p < 0.000...

An 80-year-old man underwent an electrophysiologic procedure because of recurrent episodes of supraventricular tachycardia. Episodes of nonsustained narrow QRS complex tachycardia occurred spontaneously after catheter placement. Examples of the onset and termination of an episode of tachycardia are shown in Figures 1 and 2, respectively. What is the mechanism of the tachycardia? What is the lev...

The QRS is the most prominent feature in ECG signal, that correspond to the ventricular contraction ,the time of its occurrence as well as its shape provide much information about the current state of heart. There are many technique to delineation of QRS complex. This paper discusses various method for proposed earlier for delineation of QRS Complex. This paper provide also depth study of QRS d...

The ability to evaluate various Electrocardiogram (ECG) waveforms is an important skill for many health care professionals including nurses, doctors, and medical assistants. The QRS complex is a vital wave in any ECG beat. It corresponds to the depolarization of ventricles. The duration, the amplitude and the complex QRS morphology are used for the purpose of cardiac arrhythmias diagnosis, cond...

The occurrence of the R peak (tR), and the area of the QRS complex (AQRS) are among the features estimated from each ECG wave. To estimate these parameters ECG is traditionally sampled at a high sampling rate (250-500Hz). However, since tR and AQRS are identified by the selective analysis of the QRS complex and since the QRS maximal frequency component is about 25 Hz, we propose a new procedure...

This paper presents a novel algorithm to detect onset and duration of QRS complexes. After low-pass filtering, the ECG signal is converted to a curve length signal by a transform in which a nonlinear scaling factor is introduced to enhance the QRS complex and to suppress unwanted noise. Adoptive thresholds are applied to the length signal to determine the onset and duration of the QRS complex. ...

An electrophysiologic procedure was performed in a 50-year-old man with a 20-year history of paroxysmal tachycardia. During sinus rhythm, the atrial-His (AH) interval was 70 msec, the His-ventricular (HV) interval was 45 msec, and the QRS width was 80 msec. During atrial pacing at a cycle length of 290 msec, there was widening of the QRS complex (Fig. 1). The transition from a narrow to wide QR...

BACKGROUND The QRS complex is the most noticeable feature in the electrocardiogram (ECG) signal, therefore, its detection is critical for ECG signal analysis. The existing detection methods largely depend on hand-crafted manual features and parameters, which may introduce significant computational complexity, especially in the transform domains. In addition, fixed features and parameters are no...

The ECG (electrocardiography) shows a sinus bradycardia of 42 beats/min, a horizontal electrical heart axis and a narrow QRS complex. The second to fourth QRS complex is preceded by a P wave with a variation in the PQ time. The PQ time in the second QRS complex is 220 ms, in the third 200 ms and the fourth 140 ms. No P wave precedes the fifth QRS complex. In the sixth QRS complex, the P wave is...