electrocardiograms and ECG variants


Physical examinations for FAA First Class medical certification require an electrocardiogram (a.k.a. ECG or EKG) on the first physical examination after age 35 an annually after age 40 - FAR Part 67.111 (b). Second and Third Class certification examinations do not require ECGís. Occasionally, airmen receive a letter from the Aeromedical Certification Division of the FAA indicating "a slight variance has been found on your electrocardiogram of (date)." The FAA then requires a cardiovascular evaluation (CVE) as outlined on FAA Form 8500-19, Specifications for Cardiovascular Evaluation. Other tests may be requested depending on the nature of the "slight variance."

Pilots often find these letters rather alarming. The concern may be generated because they fear their medical certificate is not valid or may soon be suspended. Concerns about the underlying health issues are also present. Frequently, the AME performing the ECG did not mention any "variance" raising questions about the AMEís thoroughness or the administrative process that may have led to a mix-up in ECGs, the "That canít be my ECG!" denial. It is important to understand some basics about ECGs and how they are processed at the FAA. Often, the situation is resolved without any consequences.

what is an Electrocardiogram?

An ECG is a graphical representation of the heartís rhythm and the sum of the electrical forces of the heart measured in 12 different directions. Other than the heart rate, an ECG is fairly stable in an individual if no physical changes in the heart have occurred. Though not as unique as fingerprints, ECGs tracings over time in a single individual should appear very similar. A single ECG is like a snapshot in time. It can not predict what will happen, but does demonstrate what has happened to a limited extent. A more detailed explanation of abnormal heart rhythms is found in our article "Arrhythmias - Abnormal Heart Beats".
Rate and Rhythm

The first of the two major areas noted in the ECG is the rhythm. A "normal sinus rhythm" requires a regular heart rate of between 60 and 100 beats per minute (bpm). It also requires that for every signal generated in the natural pacemaker of the heart (sinus node) located in the left upper chamber of the heart (atrium), a signal is conducted to the two lower chambers of the heart (ventricles). Faster rates are termed "tachycardia" while slower rates are termed "bradycardia". There are both benign and significant causes for each of these conditions. If the heart rate is not regular or there is a prolonged delay in the conduction of the signals, terms such as fibrillation, flutter and heart block are used depending on the finding. Most are aeromedically significant and some are medically significant, particularly if they represent a change from a previous ECG.

ECGís sent to the FAA with irregular heart rates will trigger a request for a CVE with a Holter monitor report. The Holter monitor is a 12-24 hour recording of the heart rate analyzed by a computer for abnormalities. Rather than the 6 second snapshot of a routine ECG, this is a feature length ECG movie. The Holter does not give specific information about coronary artery disease or heart structure. The Holter monitor involves several wire leads attached to the body and fed into a transistor radio sized device worn on the belt for the duration of the test. At the completion of the test, the device and leads are removed for analysis. Individuals are often requested to keep a diary of activity to accompany the Holter and push a button to make signal when they make a diary entry. This is a good idea to do, as it may explain some irregularities in the heart rhythm. A rate of 145 bpm is suspicious if unexplained, but a note that you were exercising during that time is reassuring. Likewise, a rate of 40 may be normal when sleeping. Abnormal arrhythmia's discovered on ECGs will require full explanation. Significant arrhythmia's may be associated with not only heart disease, but also with loss of consciousness. Non-cardiac causes of arrhythmia's, such as caffeine, medication or an overactive thyroid, may easily be corrected.

electrical Forces

The second broad area evaluated by an ECG is the total electrical forces of the heart in each of 12 directions. This may give general information about the function of the heart muscle and its electrical components, the thickness of the ventricles, the workload or areas of previous damage to the heart. Six of the twelve axes measure the electrical sum in the frontal plane, parallel to the shoulders. The electrical activity should move toward the lower left quadrant. Six leads measure electrical activity in the horizontal plane, parallel to the ground. The net electrical activity should be forward and to the left. Activity in a different direction may indicate damage to the heart, increased workload or problems with the heart valves. This information is non-specific, but may indicate the need for other more definitive testing.

The spikes and waves of an ECG should fall within standardized heights and duration. Again, deviations may indicates similar problems as above. The presence of extra waves or spikes may indicate previous heart damage or chemical abnormalities. Further tests are needed to confirm these suspicions.

Abnormalities in these areas may lead to requests for echocardiograms if structural abnormalities are suspected. the echocardiogram is an ultrasound and Doppler study of the heart structures and blood flow through the heart. If decreased blood flow from coronary artery disease or a previous heart attack is suspected, one of several types of treadmill exercise stress tests is requested. Certain delays in conduction of the electrical signals, particularly "bundle branch blocks" of new onset also trigger requirements for treadmills or stress tests.

FAA Letters for 'a slight variance from normal'

Why does the FAA send out these letters? Obviously, if one of the above abnormalities is discovered, further evaluation is appropriate for aviation safety. However, there are several administrative reasons why a letter would be generated with a medical cause. The FAA maintains a library of all the ECGs done by pilots. Some ECGs are sent to the FAA in hardcopy while some are sent electronically. ECGs received are compared to previous ECGs on the same pilot. Changes from previous ECGs trigger this letter. Some changes may be significant, but others may arise from different causes. Examples include incorrect placement of ECG leads on the chest or limbs, electronic "noise" interfering with the transmission or failure to successfully transmit electronic or hardcopy ECGs. In the near future, all AMEs performing First Class exams must transmit ECGs digitally using specialized equipment. This will eliminate most transmission problems and inconsistencies between different types of ECG machines used.

Pilots - What To Do About the Letter

What should pilots do if they get a letter requesting a CVE from the FAA for "a slight variance in your ECG"?

First, donít panic! Pilots can request an extension to the 30 day deadline. Otherwise, failure to report within the 30 day suspense may result in an automatic denial.

Next, complete all aspects of the FAA CVE and any other FAA directed tests. These tests are not usually done by your AME. Rather they are done by your private physician or a consulting physician you may be referred to for testing. If your physician recommends additional tests BECAUSE THEY ARE MEDICALLY INDICATED, do the testing and protect your health. We strongly advised AGAINST doing testing that is not medically indicated "just because the FAA might want to see it." If the FAA wanted it, they would ask for it. This can cause significant problems and expense. As long as you are still flying, donít worry about second guessing the FAA.

FAA Reporting

Send the tests in to the address specified on your letter using the identification number listed on the top in a cover letter. Keep a copy of everything. The FAA will acknowledge your submission in 3-12 weeks. Three possible responses are seen. Your eligibility for an airmanís certificate will be confirmed, you will have further testing requirements specified, or rarely, your certificate will be denied. You have 30 days to appeal any denial. Keep a copy of the FAA response and have it available for your next physical exam.

The completed Cardiovascular Evaluations listed on FAA Form 8500-19 and other test results may be mailed to the FAA at :

Federal Aviation Administration
Aeromedical Certification Division
CAMI Bldg./ AAM-300
P.O. Box 26080
Oklahoma City, OK 78126-9922