how do we Differentiate between complete AV block due to nodal pathology from junctional rhythm with complete av dissociation?
Complete AV block and junctional rhythm with complete AV dissociation can appear similar on an electrocardiogram (ECG). However, there are some key features that can help differentiate between them.
In complete AV block due to nodal pathology, there is a complete interruption of the electrical impulses between the atria and ventricles. This results in the ventricles contracting at their own intrinsic rate, which is typically slower than the normal heart rate. On the ECG, there will be a regular P-wave rhythm originating from the sinus node, but with no association between the P-waves and QRS complexes. The QRS complexes will be narrow and regular, reflecting the intrinsic rate of the ventricles.
In contrast, in junctional rhythm with complete AV dissociation, the atria and ventricles are each beating independently of one another. The rhythm originates from the AV node or the bundle of His, resulting in a narrow QRS complex. On the ECG, there may be retrograde P-waves (inverted P-waves) after the QRS complexes, or there may be no visible P-waves at all. The ventricular rate is typically slower than the normal heart rate.
Therefore, the presence of retrograde P-waves or a lack of visible P-waves on the ECG can help differentiate junctional rhythm with complete AV dissociation from complete AV block due to nodal pathology. Additionally, a patient’s symptoms and medical history, as well as additional diagnostic tests such as echocardiography, can also aid in the differentiation.