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PQ interval shortening
Medical expert of the article
Last reviewed: 05.07.2025
Causes of shortening of the PQ interval
These changes in cardiographic readings are a symptom of the formation of indirect conduction pathways and may cause paroxysmal supraventricular tachycardia (one of the types of arrhythmia). However, such a symptom may not be a pathology, but just an asymptomatic ECG sign.
A shortened interval in the absence of any symptoms may be one of the normal variants or a result of increased sympathetic tone. Such manifestations are not dangerous and should not worry the patient.
A prolonged PQ interval may be observed in the presence of vagal influence, with the use of sedatives or beta-blockers, which may confirm a functional cause for the short PQ interval.
The pathological nature of the shortening of this interval can be detected with a low atrial or AB-nodal rhythm, or with early ventricular excitation. This situation can be distinguished by examining the P wave.
In some patients, a short PQ interval is associated not with the appearance of an indirect pathway, but with a short impulse movement along the AB node. This situation can be observed in people who have had a myocardial infarction: they also have periods of ventricular arrhythmia.
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Short Q syndrome
This syndrome was scientifically described back in 1938, when scientists analyzed two hundred similar cardiograms. Interestingly, most patients with this syndrome did not have any heart pathology. Only 11% were diagnosed with paroxysms of supraventricular tachycardia. A short PQ interval is a form of arrhythmia.
The term "ventricular pre-excitation phenomenon" implies the corresponding ECG signs in the absence of arrhythmia, and ventricular pre-excitation syndrome is a combination of ECG signs with paroxysmal tachycardia. It follows that the phenomenon of shortening of the PQ interval is the detection of a PQ interval on the ECG with an indicator less than 120 ms (0.12 s) in an adult patient and less than the age norm for children (provided there is no arrhythmia). The syndrome of a short PQ interval is a combination of ECG signs with paroxysmal supraventricular tachycardia.
Shortening of the PQ interval in adults is an interval value of less than 0.12 s. It indicates that the impulse passes too quickly from the atrium to the ventricles. Whether this sign is an indicator of premature ventricular excitation, which is considered a conduction disorder and is a separate type of arrhythmia, is decided by a specialist.
Shortening of the PQ interval in children depends on the child's age and is often observed in infants, less often in adolescence. This may be due to age-related features of the interval duration and anatomical changes in the AB node. Today, in practice, the PQ interval length indicators are used depending on the child's age period, but the diversity of data from different authors complicates the diagnosis of a shortened interval in pediatrics. These criteria require significant improvement and revision, with the definition of clear interval values according to age and the frequency inherent in the main rhythm.
Symptoms of Shortened PQ Interval
If the appearance of a short interval on the ECG is not related to the asymptomatic course and is considered a deviation from the norm, then the patient may show signs of periodic paroxysmal tachycardia - rapid heartbeat lasting several seconds (10-20 sec) and passing more often on its own and without consequences. Such attacks can occur at different periods of time, sometimes they are associated with a stressful situation, but often the cause remains unclear.
Spontaneous tachycardia may be accompanied by a feeling of discomfort behind the breastbone, panic fear, pale skin, and sweat on the face.
Unpleasant sensations are not always present; often the patient does not even suspect that he has a cardiac pathology.
Shortening of the PQ interval on the ECG is measured from the initial point of the P wave to the initial point of the Q wave: usually, a rapid rhythm and a short interval are interrelated. Normal values are usually considered to be from 120 to 200 ms.
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Treatment of shortened PQ interval
Shortening of PQ against the background of normal heart rhythm and absence of clinical cardiological symptoms does not require treatment. The presence of any heart pathology, arrhythmia, paroxysmal tachycardia, myocarditis, infarction requires a more thorough cardiological examination and prescription of appropriate treatment.
Modern medicine offers a catheter method of therapy for many types of tachycardia, including those with a shortened PQ interval. The use of radiofrequency catheter ablation and cryoablation is carried out depending on the nature of a specific arrhythmia.
Of course, the underlying cause of this condition also needs to be treated. And the cause can only be determined by a specialist based not only on an ECG, but also on all sorts of additional research methods.
Prevention of PQ interval shortening
Even if the ECG shows a reduction in the PQ interval, if you have never been bothered by tachycardia attacks, the chances of them occurring in the future are very low. This condition is not dangerous and no therapeutic or preventive measures are required.
If the clinical picture of cardiac pathologies is obvious, then, first of all, you should consult a doctor and undergo further examination.
Among the general methods of preventing heart disease, the following can be distinguished:
- active lifestyle, moderate physical activity;
- fight against excess weight;
- complete, high-quality nutrition;
- a clear refusal to smoke and drink alcohol;
- limiting the amount of salt consumed;
- good rest, good sleep.
Try to avoid stressful situations, don't worry without reason, take care of your nerves and don't take it out on others. Travel more, communicate with friends, with family, enjoy every moment of life.
Prognosis of PQ interval shortening
In patients with shortened PQ intervals who are asymptomatic, the prognosis is positive because the possibility of rapid transmission of impulses via the indirect pathway is quite low.
An exception may be patients with a burdened heredity such as sudden deaths among immediate relatives. Professional athletes and test pilots may also be considered exceptions.
In patients with complaints of paroxysmal tachycardia attacks, the risk of complications is significantly higher. The use of antiarrhythmic therapy and radiofrequency ablation in their case significantly improves the prognosis of the disease.
If you have been diagnosed with a shortened PQ interval, do not jump to conclusions: a consultation with a cardiologist is mandatory, and only a specialist can accurately tell you all the information about your condition. And do not worry in advance - perhaps there is no reason for this.