Rapid heart rhyhtms and their treatment
The normal heart beat is initiated in a natural pacemaker, a collection of specialised conducting cells, in one of the upper chambers of the heart (the right atrium). This impulse travels from this chamber via a channel of conducting tissue to spread into the lower heart chambers (the ventricles). It causes the heart muscle to contract rhythmically which, in turn, pumps blood to the lungs and around the body. Abnormalities of this system include a second and abnormal channel through which the impulse can also pass from the upper chambers to the lower, or more importantly from the lower chambers back into the upper ones. If the latter happens, a self-perpetuating rapid heart rate (tachycardia) may occur which can cause inefficient pumping of blood and the risk of an incapacitation.
One example of this type of heart abnormality is called the Wolff-Parkinson-White (WPW) pattern, when it only appears on an electrocardiogram (ECG), or WPW syndrome, when it is associated with rapid heart rates. There is a typical resting ECG appearance which shows the heart impulse transmitted down the abnormal channel (this is called pre-excitation) as well as the normal way. This is usually an unexpected finding on a pilot’s ECG at the initial medical examination, but the pattern can also appear intermittently, and may only be discovered during a pilot/ATCO’s career.
Applicants who present with this pattern on an ECG will require further tests to determine the risk of a rapid heart rate occurring. These include tests to try and stimulate the heart to go into an abnormal rhythm under controlled conditions. If the tests are satisfactory (ie, it is difficult or impossible to provoke an abnormal rhythm) certification is possible. This is shown in the protocols at the foot of this page.
If the tests are not satisfactory in the WPW syndrome, or if there are other causes of recurring tachycardia (includes atrio-venticular nodal re-entry tachycardia (AVNRT), atrial flutter and atrial fibrillation) then certification is not possible without treatment. The UK CAA would always discourage a person from having such treatment purely to gain a medical certificate, but it may actually be advised by your doctors on general health grounds. During this treatment a small electrode is introduced into the heart chambers, the offending area of the heart which conducts the aberrant impulse is located, and it is then destroyed with an electrical current. This is called ‘ablation’ and is now a common procedure for many types of abnormal heart rhythm.
The protocols for certificaiton are given below.