Ecg features of supraventricular tachycardia
Ecg features of supraventricular tachycardia Supraventricular tachycardia (SVT) is a common arrhythmia characterized by episodes of rapid heart rate originating above the ventricles. Its hallmark is a sudden onset and termination of fast, regular rhythm that can cause symptoms ranging from palpitations and dizziness to chest discomfort. Accurate recognition of its electrocardiogram (ECG) features is essential for diagnosis and appropriate management.
Ecg features of supraventricular tachycardia On the surface, the ECG during SVT typically displays a narrow QRS complex, usually less than 120 milliseconds, due to the normal conduction pathway through the ventricles. This narrow complex morphology is a key feature because it suggests that the origin of the dysrhythmia is above the ventricles, within the atria or the atrioventricular (AV) node. The regularity of the rhythm is often maintained, with the heart rate commonly ranging between 150 and 250 beats per minute, although it can vary.
A central aspect of identifying SVT involves analyzing the P wave morphology and its relation to the QRS complex. In many cases, P waves are either hidden within the QRS complex or appear immediately after it, making them difficult to discern. When visible, P waves may be abnormal in shape or position, reflecting the atrial origin of the rapid activity. For example, in atrioventricular nodal reentrant tachycardia (AVNRT), the P wave often appears as a pseudo R’ in lead V1 or as a small negative deflection in inferior leads, due to retrograde atrial activation.
Another key ECG feature is the RP interval—the time from the start of the P wave to the subsequent QRS complex. In typical SVT, this interval tends to be short, usually less than 70 milliseconds, indicating that atrial activation is closely linked to ventricular activation. Conversely, in atypical SVT or certain reentrant tachycardias, the RP interval may be longer, sometimes exceeding 100 milliseconds, which can help differentiate between types. Ecg features of supraventricular tachycardia
Ecg features of supraventricular tachycardia The morphology of the QRS complex during SVT generally remains narrow; however, it can occasionally widen if there is aberrant conduction, such as bundle branch block, or pre-existing conduction abnormalities. The presence of atrioventricular dissociation, where atrial and ventricular activities are independent, is uncommon in typical SVT but may be observed in some cases, especially when there is concurrent conduction disease.
Electrocardiographic differentiation of SVT from other tachyarrhythmias like ventricular tachycardia hinges on these features. The narrow QRS complex, rapid and regular rhythm, and P wave behavior are essential clues. In certain cases, additional maneuvers such as vagal stimulation or administration of adenosine can transiently block AV nodal conduction, revealing underlying atrial activity and confirming the diagnosis. Ecg features of supraventricular tachycardia
Ecg features of supraventricular tachycardia Understanding the ECG features of SVT not only facilitates accurate diagnosis but also guides therapeutic strategies, including pharmacological interventions, vagal maneuvers, or catheter ablation. Recognizing these distinctive features ensures timely treatment and reduces the risk of adverse outcomes associated with misdiagnosis.
In summary, the hallmark ECG features of SVT include a narrow QRS complex, a rapid and regular rhythm, often indistinct P waves, and a short RP interval in typical cases. Careful analysis of these characteristics allows clinicians to distinguish SVT from other causes of tachycardia and to implement appropriate treatment plans.
