What is a sinus rhythm?
Sinus rhythm is the healthy and normal rhythm of the heart. In sinus rhythm, the electric impulse initiation occurs at the sinus node, called the heart’s natural pacemaker. The sinus node is found in the right atrium of the heart [1, 2].
The normal heart rate of a sinus rhythm in adults is between 60 to 100 beast per minute [3].
Characteristics of Sinus Rhythm
The sinus rhythm is a regular and stable heart beat. The regularity can be recognized from the normal and constant distance between the RR intervals on the ECG [4].
As the rhythm starts at the sinus node, it will have monomorphic P waves, which have regular intervals between each other [3, 2].
On the ECG after the P wave, in a normal sinus rhythm, narrow QRS complex are present [2].
The sinus rhythm rate should not exceed 100 beats per minute (BPM). A heart sinus action with a beat that is faster than 100 BPM will be called sinus tachycardia. Lower heart rate than then 60 BPM and a sinus rhythm, on the other hand, is called bradycardia [1].
What is a sinus rhythm with PJC?
A sinus rhythm with PJC or premature junctional contractions is a normal sinus rhythm that occasionally is interrupted by an early heart beat from the junctional area.
Anatomically, this areas is found around the atrioventricular node [5].
The PJC occurs before the normal sinus node initiated impulse and can lead to a feeling of a skipped beat or palpitation.
Presence of the PJC in a sinus rhythm can occur in healthy heart. However, it can also be a sign of a heart disease.
On the ECG, PJC presents with a narrow QRS complex. They can be preceded by an inverted or no P wave [6].
Also, commonly after PJC, a compensatory break occurs as the impulse can reset the atria [6].
Is PJC with a sinus rhythm dangerous?
Generally, PJC are considered benign. They can be found also in completely healthy people. PJC can occur, for example, due to an suppression of the vagal tone [7] like in stress and emotional reaction [8]. In such situations, if the PJC is not symptomatic, no treatment is necessary [7].
However, sometime PJC can be linked to more dangerous conditions. For instance, PCJ can lead to a junctional tachycardia and followed by low blood pressure [7].
Moreover, the junctional tachycardias coming from PJC can develop into other arrhythmias. A PJC can develop into, for example, atrial fibrillation [6].
Should I see a cardiologist if I have a sinus rhythm with PJC?
A sinus rhythm with PJC can occur in healthy people. However, it can also indicate an underlying heart condition and can be linked to arrythmias.
In healthy individuals, PJC occurs particularly when under stress or during perioids of excessive alcohol and caffeine intake [7].
Nevertheless, it is recommended that a cardiologist confirms the benign character of the PJC condition and excludes any potential complications.
Moreover, a strong indication to visit a cardiologist is when you have a sinus rhythm with PJC and accompanying symptoms as: