Clinical Assessment of Complete Heart Block and Asthma Diagnosis

Cardiac and Respiratory Assessment Findings

Dizziness and Cardiac Conduction Issues

The blackouts do not seem to have had any relationship to posture. They have been a mixture of dizziness and loss of consciousness. The one witnessed episode seems to have been associated with loss of color. This suggests a loss of cardiac output, usually associated with an arrhythmia. This may be the case despite the absence of any other cardiac symptoms. There may be an obvious flushing of the skin as cardiac output and blood flow return.

The normal ECG and chest X-ray when the patient attended hospital after an episode do not rule out an intermittent conduction problem. On this occasion, the symptoms have remained in a more minor form. The ECG shows third-degree or complete heart block. There is complete dissociation of the atrial rate and the ventricular rate, which is 33/min.

The episodes of loss of consciousness are called Stokes–Adams attacks and are caused by self-limited rapid tachyarrhythmias at the onset of heart block or transient asystole. Although these have been intermittent in the past, the patient is now in stable complete heart block. If this continues, the slow ventricular rate will be associated with reduced cardiac output, which may cause:

• Fatigue
• Dizziness on exertion
• Heart failure

Intermittent failure of the escape rhythm may cause syncope.

Shortness of Breath and Asthma Assessment

The peak flow pattern shows a degree of diurnal variation. This does not reach the diagnostic criteria for asthma, but it is suspicious.

Peak Flow Data Analysis

The mean daily variation in peak flow from the recordings is 36 L/min, and the mean evening peak flow is 453 L/min, giving a mean diurnal variation of 8 percent. There is a small diurnal variation in normals, and a variation of +15 percent is diagnostic of asthma.

In this patient, the label of 'bronchitis' as a child was probably asthma. The family history of an atopic condition (hay fever in a brother), and the triggering of the cough by exercise and going out into the cold also suggest bronchial hyper-responsiveness typical of asthma.

The diagnosis of asthma was confirmed with an exercise test, which was associated with a 25 percent drop in peak flow after completion of 6 minutes of vigorous exercise.

Alternative Diagnostic Challenges

Alternatives to the exercise test would have been another non-specific challenge, such as:

• Methacholine
• Histamine
• A therapeutic trial of inhaled steroids