Ashman Phenomenon

The patient is a 27 year old previously healthy man who is the the father of a three month baby.  He presented with palpitations for the past two hours. He felt light headed but did not have chest discomfort or shortness of breath. He had not taken any drugs or alcohol before the palpitations began. There was no past history of palpitations or heart disease. An uncle diagnosed with Marfan's syndrome had died suddenly in his thirties.

On examination the patient's pulse was irregular at a rate of about 180 - 200 per minute. His blood pressure was normal. The patient was tall and thinly built.

Figure 1 shows an ECG taken at 2000 hours.

Figure 2 shows the patient's chest X-ray


Figure 1.  ECG_0015_A



Figure 2. Chest Xray of Case ECG_0015

Describe the main findings in the chest Xray


Describe the main findings in ECG_0015_A

Figure 3.  Rhythm stipfrom ECG_0015_A

The rhythm strip (Figure 3) shows a narrow complex tachycardia with a ventricular rate of about 200 per minute and irregular R-R intervals. Two types of QRS complex are present:

  • Most of the QRS complexes (twenty three of the twenty five complexes)  have a Rs shape, with or without a small Q-wave. The amplitude of these complexes varies, but not in a regular electrical alternans pattern.
  • Two complexes (labelled 1 and 2)  are smaller and slightly wider, and are either ventricular ectopic beats or beats of atrial origin that are aberrantly conducted.

The irregular R-R intervals indicate that the underlying rhythm is atrial fibrillation.  There are occasional upright deflections that might be P waves (the blue arrows).   These P-wave like undulations do not occur in a regular or predictable pattern, and are due to the atrial fibrillation.
The two R-R intervals (labelled A and B) that precede the complex labelled 2 have a long-short pattern.  This is a feature of the Ashman phenomenon, which occurs when a (moderately) long cardiac cycle is followed by a (comparatively) short cardiac cycle.  The length of the ventricular refractory period is increased by the slower heart rate i.e.  after the longer R-R interval labelled A. The next atrial impulse (labelled 2 in the rhythm strip)  arises earlier,  when the His-Purkinje system is still partially refractory.  The resultant different shape of complex 2 is thus due to impaired (aberrant) conduction and not to a ventricular ectopic origin. The Ashman phenomenon is a feature of atrial fibrillation.

Incomplete right bundle branch block is present: there are S waves in Lead I and Lead V6,  the complexes in V1 and V2  have a rSr shape and the QRS duration is 90 msec.  The axis is 90 degrees,  which is normal for the patient's age. However the combination of a rightward axis and incomplete right bundle branch block in the setting of new onset atrial fibrillation raises the possibility of right heart abnormality.  

Summary of main ECG findings:

  1. Atrial fibrillation with a ventricular rate of about 200 beats per minute
  2. Incomplete right bundle branch block and aaxis of 90 degrees
  3. Ashman phenomenon

The patient is treated with beta blockers, and a repeat ECG is taken at 2209 hours (Figure 4)

Figure 4. ECG_0015_B

Describe the main findings in ECG_0015_B

What are the major management issues in this case?