What is Ashman Phenomenon?
The Ashman phenomenon is a term first introduced by Dr Gouaux and Dr Ashman in 1947. They explained that when an early and out-of-step contraction in the upper chambers of the heart (a premature atrial contraction, or PAC) happens, especially after a long cycle, it often results in abnormal electrical conduction in the heart. This abnormal conduction changes the usual route of the electrical pathways. However, this deviation doesn’t affect the patient’s survival rate or disease progression.
This phenomenon is often mistaken for a premature ventricular contraction (PVC) because of how it appears on a heart rhythm test (EKG) as a single, broad wave pattern. This pattern can appear in patients with an irregular heart rate (atrial fibrillation) or in other fast upper heart rate disorders. It typically results in single, wide wave patterns, referred to as aberrant complexes.
The Ashman phenomenon doesn’t actually cause any symptoms itself because it’s more of a medical observation rather than a disease. Any symptoms a patient may feel are actually caused by the underlying heart condition. Often this condition is an irregular heartbeat (atrial fibrillation).
What Causes Ashman Phenomenon?
The Ashman phenomenon, or Ashman beat, refers to a specific pattern seen on a heart activity test, known as an EKG. It looks like a wide QRS complex that shows up after a short RR interval, which was preceded by a long RR interval. The QRS complex originates from above the AV node in the heart, not directly from the right or left ventricle. This makes it appear as a right or left bundle branch block. This happens when the refractory period (the time when the heart cell can’t reactivate after a heartbeat) is proportional to the previous RR interval. A shorter RR corresponds to a shorter action potential duration, while a longer RR corresponds to a longer action potential duration. When a short RR follows a long one, the beat is likely to be conducted aberrantly.
This aberrant conduction happens because the refractory period of the right bundle is longer than that of the left, hence when a beat gets to the His-Purkinje system (part of the electrical system of the heart), the right bundle may still be in a refractory period. This results in blocked conduction through one bundle, leading to a heart activity pattern with bundle branch block morphology. A right bundle branch block pattern is more commonly seen, but a left bundle branch pattern can also occur, albeit less frequently. This pattern can be associated with left fascicular blocks.
Doctors can diagnose the Ashman phenomenon using the Fisch criteria, a set of rules initially established by Dr Charles Fisch. These include certain irregularities in the heart rhythm noticed on an EKG, irregular timing between aberrant QRS complexes, and lack of a full compensatory pause. The degree of aberrant conduction can vary from beat to beat and from one patient to another. A right bundle branch block pattern is more common, while a left bundle block pattern or combined block pattern may sometimes appear in the same patient. If both patterns were noted, the patient likely has a heart block, and an Ashman beat would not be present.
It’s easy to confuse the Ashman phenomenon with premature ventricular complexes due to their similar appearance on an EKG. It’s vital to differentiate between them as they often get mistaken for each other. While both patterns can have a widened QRS, small differences can be spotted. If the widening of the QRS complex occurs at regular intervals, it would support the diagnosis of premature ventricular complexes rather than the Ashman phenomenon. If a full compensatory pause is observed, then it would suggest a ventricular origin of the beat, whilst a lack of compensatory pause would suggest aberrancy. Overall, the shape of the QRS complex is the most critical clue to distinguish between a supraventricular or ventricular origin of wide QRS complexes.
Risk Factors and Frequency for Ashman Phenomenon
There isn’t any available data about the geographic differences related to the Ashman phenomenon. This phenomenon is associated with conditions that affect the heart’s electrical system, meaning it’s typically linked to an irregular heartbeat. The Ashman beat is frequently identified in heartbeat tests (EKGs) in medical practice, although it’s commonly misinterpreted.
Signs and Symptoms of Ashman Phenomenon
The Ashman phenomenon typically doesn’t cause any symptoms. However, a person might feel symptoms like heartbeat sensations (palpitations), breathlessness, or feeling faint. These symptoms are usually due to other heart rhythm conditions like atrial fibrillation or rapid heartbeat in the upper heart chambers. It’s important to note that these symptoms are not caused by the abnormal contraction associated with the Ashman phenomenon. This condition is often observed in people with irregular heart rhythms, particularly those with atrial fibrillation. This is an irregular, often rapid heart rate condition. Ashman’s phenomenon is an abnormality often seen on ECG tests of people with atrial fibrillation, which is due to changes in heart beat intervals and abnormal heart rhythms.
Testing for Ashman Phenomenon
When doctors need to examine a patient displaying the Ashman phenomenon, they often start with a procedure called a 12-lead electrocardiography. This is a test that checks the electrical activity of your heart to see how it’s working. In some situations, where it’s challenging to determine the basic heart rhythm, more complex tests called electrophysiological studies may be required. However, it’s important to note that there are no specific laboratory tests commonly associated with Ashman phenomenon.
Treatment Options for Ashman Phenomenon
There’s no need for treatment if you have isolated complexes. However, if you have a heart condition, such as irregular heartbeats known as atrial fibrillation, you might need treatment to control your heart rate or rhythm.
What else can Ashman Phenomenon be?
Doctors need to properly identify whether abnormal heart rhythms (arrhythmias) come from the lower chambers of the heart (ventricles), or from the upper chambers of the heart with aberrancy, as they have different treatments. Accurate diagnosis can ensure the most effective treatment for the patient.
What to expect with Ashman Phenomenon
The Ashman phenomenon is a harmless condition that does not affect a patient’s risk of death or illness.
Possible Complications When Diagnosed with Ashman Phenomenon
There have been no reported complications associated with the Ashman phenomenon, according to existing scientific literature.
Preventing Ashman Phenomenon
If someone experiences heart palpitations, chest pain, difficulty breathing, dizziness, or fainting spells, they should quickly seek medical attention. Although these symptoms may not usually be associated with the Ashman phenomenon, they could indicate a more serious heart-related issue, such as an irregular heartbeat or other heart rhythm disorders.
