PR interval prolongation needs to be judged according to the time and pattern to determine the severity, such as one degree and two degrees of type 1 AV block can be observed, while two degrees of type 2 and three degrees need to be treated.
PR interval is the period of time from the beginning of P wave to the beginning of QRS wave cluster on electrocardiogram, which can be a good assessment of the function of AV node, and the normal duration is 0.12~0.20 seconds.
1. First-degree and second-degree type 1 atrioventricular block: the former ECG shows a regular P-wave pattern and both are followed by QRS waves, with PR intervals ≥0.20 seconds. In the latter case, the electrocardiogram shows an irregular PR interval, regular P waves, progressive prolongation of the PR interval until a QRS wave is shed after the P wave, and a normal QRS wave group time frame and morphology.
Generally, patients are asymptomatic, need special treatment, and can be observed.
2. Second-degree type 2 and third-degree atrioventricular block: in the former, the ECG shows a regular P-wave pattern with a fixed prolongation of the PR interval until one QRS wave is shed. In the latter case, the P wave is not related to the QRS wave, each with its own pattern, and the number of P wave > the number of QRS wave.
Patients with mild symptoms should undergo etiologic treatment, such as discontinuing medications such as metoprolol, correcting hypoxemia, etc., and installing a pacemaker if hemodynamic instability occurs.
Patients with PR interval prolongation should have a clear diagnosis under the guidance of a doctor, standardize the treatment if necessary, and stop and use the medication as prescribed by the doctor to avoid delaying the condition.