Introduction

The human heart is the organ responsible for pumping blood to all parts of the body. The efficiency of the pumping action is related to three primary factors. These factors include the strength of the muscular contractions, the amount of resistance to blood flow across valves in the heart, and the coordinated, rhythmic pumping of each of the chambers of the heart. Specialized muscle cells that act as electrical conduits through the heart and natural pacemakers determine the rhythm of the heart. The graphical representation of the heart’s electrical activity is called an electrocardiogram or ECG.

Pilots applying for First Class medical certification are required to submit an ECG with the first application after their 35th birthday and annually with subsequent evaluations after the 40th birthday. The ECG must be submitted electronically to the FAA ECG Library by the AME at the time of the physical examination, or by a company medical doctor within the 60 days prior to the physical by the AME.

This article explains at a basic level the physiology of heart rhythms, some common abnormal rhythms, possible treatments and aeromedical certification implications. There are many other types of arrhythmias not discussed here as well as evaluation and treatment options available to cardiologists and electrophysiologists.

Normal Sinus Rhythm

The "normal" electrical signals within the heart are defined in terms of the rate of signals and the rhythm of the signals. The normal heart rate is between 60 and 100 beats per minute in the average adult. Rates slower than 60 beats per minute (bpm) are termed "bradycardia" while rates faster than 100 bpm are termed "tachycardia." Heart rates outside the "normal range" indicate a healthy response of the heart or may reflect malfunction and disease. For example, the resting heart rate of an aerobically conditioned athlete may be in the 40’s or 50’s, while the appropriate heart rate response to exercise may be an elevation to rates above 150 beats per minute.

Medications and disease conditions will affect the heart rate. Slow heart rates (bradycardia) can be caused by some blood pressure medications such as beta-blockers or diseases such as hypothyroidism (low thyroid activity). Heart disease can also manifest as an abnormally slow rate. Tachycardia (fast heart rate) may also reflect the effects of medications (decongestants, diet pills, thyroid medication, etc.), exercise, non-cardiac diseases such as adrenal tumors, hyperthyroidism, lung disease, imbalances of the blood’s electrolytes, dehydration, anemia (low blood count) and many others.

Irregular heart rates, termed "arrhythmias" or "dysrhythmias" generally require a more extensive evaluation to exclude underlying heart diseases, the most common cause. Some cases of dysrhythmias are not associated with any significant disease or are transient in nature. ECG’s or more extended monitors of heart rhythm are useful in diagnosing arrhythmias. Disturbances of the heart rhythm are generally categorized as "brady-" (slow) or "tachy-" (fast) arrhythmias. This categorization is frequently important in determining treatment as well as providing clues to possible causes.

Causes of Arrhythmias

As mentioned above, a wide variety of non-cardiac conditions and medications can affect the heart rate and rhythm. The common element in most of these conditions is the effect they have on nerves going to the heart. This portion of the nervous system is called the autonomic nervous system and has two major components. Nerves of the sympathetic nervous system generally stimulate the heart to beat faster and may stimulate irregularities in the heart beat. Nerves of the parasympathetic nervous system, primarily the vagus nerve, act to slow the heart rate.

Disease of the coronary arteries, which supply blood to the heart muscle (myocardium), may cause damage to the rate- and rhythm-setting electrical myocardial fibers. Congenital anatomical defects of the heart and diseases of the heart itself, such as myocarditis, sarcoid and pericarditis may cause dysrhythmias. In many cases of dysrhythmias, no specific cause is ever discovered, particularly in younger individuals.

Anatomy of Heart's Electrical Conduction System

The heart’s electrical conduction system is responsible for setting the rate and rhythm to all sections of the heart and coordinating the activity for the most efficient operation of the four chambers of the heart. While all muscles, including the heart, have some intrinsic electrical properties, the heart has several portions of very specialized, electrically active myocardial cells.

The two upper chambers of the heart, called the right atrium and left atrium, receive blood returning from the body (right) or the lungs. They are relatively thin walled and do not pump very forcefully, as they only have to pump blood to the adjacent lower chambers of the heart, called the right and left ventricles. The right ventricle is of medium thickness and it is responsible for pumping blood a short distance to the lungs where the blood is re-oxygenated. The left ventricle is a thick walled structure that must pump the oxygen rich blood returning from the lungs via the left atrium, to the entire body. The wall of myocardium between the two ventricles, called the septum, is very thick also since it participates in pumping blood to both the lungs and the body.

Sino-Atrial Node (SA Node)

In normal individuals, the heart rate is usually set by a collection of heart muscle with electrical properties near the top of the right atrium, called the sino-atrial or SA node. Depending on the individual’s physiology, the SA node serves as an electrical capacitor that discharges 60-100 times per minute. As mentioned above, many factors may affect the rate at which the SA node fires. On an ECG, the discharge of the SA node is represented by the "P wave." The electrical signal from the SA node diffuses across both atria, causing different portions of the atria to contract sequentially as the discharge spreads from the SA node like ripples in a pond. The sequential contraction of the atria is not as efficient as a simultaneous contraction of all the myocardial fibers of atria would be, but occurs in less than 0.2 seconds and is adequate to pump blood to the ventricles.

Atrioventricular (AV) Node

The atrioventricular node acts as a second electrical capacitor that is located at the junction of the two atria and two ventricles. Essentially, the AV node collects the electrical signal diffusing across the atria and holds it until ready for discharge. This is represented graphically on an ECG by the "P-R interval." In the absence of a signal from the SA node, the AV node has an intrinsic rate of discharge of 40-60 per minute. Because the SA node sends signals at a faster rate, the AV node usually discharges at the same rate as the SA node.

His-Purkinje System

Unlike the atria which contract sequentially in response to diffusion of an electrical signal across the chambers, all portions of the ventricles must contact nearly simultaneously for efficient pumping action. To accomplish this, the AV nodes discharges its signal into a high speed conduction pathway called the His-Purkinje system. The His-Purkinje system uses three conduits to send electrical signals rapidly to both ventricles and allows the signal to spread across the thickness of the ventricular walls, rather than diffusing down the length and width of the ventricles.

There are two pathways sending signals to the thicker left ventricle, called the left anterior (front) fascicle/bundle and the left posterior (back) fascicle/bundle. There is a single pathway on the right. The ECG representation of this discharge down the His-Purkinje bundles and into the ventricles is called the "QRS complex." This entire sequence is usually less than 0.12 seconds.

The ventricles depolarize electrically when they contact. This is also represented on the ECG by the QRS complex. Immediately after depolarization, they cannot discharge until they repolarize and the electrolytes in the heart muscles, sodium, potassium and calcium, return to their normal resting balance. The period of time when they cannot discharge is called the refractory period is represented by the ST segment of the ECG. The length of the ST segment is not important in most cases, but deviations from its’ baseline may represent decreased blood flow to the heart ("ST depression with exercise") or injury such as an early heart attack ("ST elevation"). Please see the VFS article on Coronary Heart and Artery Disease for a full description of exercise stress testing. The repolarization, or resetting of the baseline electrical state of the ventricles, is represented by the "T-wave" on the ECG.

Types of Arrhythmias

The various types of arrhythmias can be broken into several subcategories: benign, bradyarrhthmias (too slow) and heart blocks, and tachy-arrhythmias (too fast). Bradyarrhythmias (slow) generally arise from some type of failure of the conducting system to conduct signals in the normal sequence or through normal pathways. Frequently, these failures to conduct signals are termed "heart blocks." Alternatively, tachy-arrhythmias result from various aberrant conduction pathways.

Benign Conditions-Sinus Arrhythmia

This condition is sometimes found as an annotation on computer generated ECG interpretations. It does not represent an abnormal condition and does not require further evaluation. Sinus arrhythmia is defined as a variability in the resting heart rate, often associated with breathing in (slows heart rate) and exhaling (speeds heart rate) due to the change in the rates the chambers of the heart fill with blood at different phases of respiration. The Guide to Aviation Medical Examiners specifically states this finding does not require evaluation and is eligible for First Class certification.

Benign Conditions-Atrial Premature Complexes (APC, APB, PAC)

If atrial premature contractions (APCs) are noted on an FAA ECG, the pilot may receive a letter from the FAA several weeks to months after the physical requiring a cardiovascular evaluation with a Holter monitor. Because up to several APCs a minute may be normal, but ECGs only evaluate a six second interval, one or more APCs on a six second ECG may represent significantly more frequent occurrences. The Holter monitor (continuous, 24-hour ambulatory ECG recording) would detect all APCs and give an hourly average. Pilots who are directed by the FAA to undergo a cardiovascular evaluation may continue to fly during the evaluation unless more serious conditions are discovered.

Occasionally, APCs may set up a re-entry cycle between the atria and ventricles. This would result in a tachyarrhythmia as noted below and has more significant implications for certification.

Benign Conditions-Ventricular Premature Complexes (VPC, VPB, PVC)

Like APCs, over 60% of normal adults will have ventricular premature contractions (VPCs) on a 24 hour Holter monitor study. Greater than six Ventricular Premature Complexes per minute are abnormal. The symptoms of VPCs are similar to those of APCs, although the pause after a premature beat tends to be longer and the subsequent contraction is more forceful. VPCs may occur in isolation, in pairs or triplets, alternating with regular beats (bigeminy) or in other regular sequences with normal beats. The VPCs may arise from a single location in the ventricle (isomorphic) or from several different locations (polymorphic) . The ECG representation is a wide QRS complex of greater than 0.12 seconds.

"Runs" of VPCs greater than three consecutive complexes is termed ventricular tachycardia (see below). This is a serious and potentially life threatening condition. More frequent and polymorphic ventricular premature beats (VPBs) also represent more significant heart conditions that should be evaluated without delay. Pilots with ventricular tachycardia are disqualified from flying pending evaluation and treatment. Those with a single isolated VPB on ECG may continue to hold a medical certificate, but should expect to receive a requirement from the FAA for a cardiovascular evaluation as noted in the section above.

Bradyarrhythmias and Heart Blocks

Bradyarrhythmias (slow) generally arise from some type of failure of the conducting system to conduct signals in the normal sequence or through normal pathways. Frequently, these failures to conduct signals are termed "heart blocks."

Bradyarrhythmias and Heart Blocks-First Degree Heart Block

First degree heart block is generally a benign condition that does not require treatment and does not have any symptoms associated with it. The electrical signal is delayed in the AV node prior to being propagated to the ventricles. Electrically, it is characterized by a P-R interval of greater than 0.2 seconds. Many aerobically conditioned athletes will have 1st degree heart block at resting heart rates. With minimal exercise, the heart rate will increase, shortening the duration of each phase of electrical activity. When the PR interval is less than 0.12 seconds, the 1st degree heart block is not present. Pilots who have slow resting pulses who are concerned about this normal variant in the ECG on their FAA physical can usually eliminate this finding by jogging in place for about 30 seconds prior to taking their ECG. First degree heart block has no effect on FAA medical certification.

Bradyarrhythmias and Heart Blocks-Second Degree Heart Blocks – Type 1 and Type 2

There are two types of 2nd degree heart block, called Type 1 and Type 2. Both are manifestations of intermittent failure to conduct the atrial electrical signals to the ventricles. Type 1 is also called "Wenckebach". The 2nd degree, Type 1 heart block manifests by a progressive lengthening of the PR interval followed by a skipped ventricular contraction or "missed beat". The implications of the two different types of 2nd degree heart block are significantly different.

Wenckebach is similar to 1st degree heart block in that it generally represents a benign condition that does not require further evaluation in an individual without heart symptoms. Like 1st degree heart block, there is a delay in the conduction through the AV node. In second degree Type 1 block, the delayed conduction is progressively longer with each beat until a beat is not conducted to the ventricles, or "blocked". The Guide to Aviation Medical Examiners specifies a cardiovascular evaluation if 2nd degree, Type 1 heart block shows on a pilot’s ECG. If no evaluation is done and the certificate is issued, the FAA may request a cardiovascular evaluation, but would not ground the pilot during the evaluation.

Second degree, Type 2 heart block is a more serious condition that may represent significant heart disease. It is characterized by delays in the AV node and randomly dropped ventricular beats (as opposed to progressively longer PR intervals). Individuals may get lightheaded, have chest pain, anxiety, loss of consciousness (Adams-Stokes attacks) or chest pain if the number of dropped beats is significant. It may progress to Third Degree (complete) heart block. This condition generally precludes FAA medical certification until the underlying cause is corrected. Often, a cardiac pacemaker is indicated to prevent possible loss of consciousness or sudden cardiac death. Pilots with cardiac pacemakers may be waived for any class of medical certificate, if no other underlying heart disease is present.

Bradyarrhythmias and Heart Blocks-Third Degree (Complete) Heart Block

Complete heart block is a very serious medical condition that generally requires immediate placement of a cardiac pacemaker as a life saving intervention. In this condition, the atria and ventricles function independently because of a complete breakdown in the heart’s electrical conduction system. Because of the slow intrinsic rate of the ventricles, usually 20-40 beats per minute, the individual can not produce enough blood flow to maintain consciousness in most situations, and may even have the heart stop beating. This condition is obviously disqualifying for FAA certification, but correction with a pacemaker may allow a Special Issuance medical certificate in rare circumstances.

Bradyarrhythmias and Heart Blocks-Bundle Branch Blocks

Bundle branch blocks are delays in the electrical conduction system below the level of the AV node, in the His-Purkinje system. In most cases, bundle branch blocks are not serious in themselves, but may indicate more serious underlying disease. Delay of signal conduction down the right bundle of the His-Purkinje system is termed "right bundle branch block". The Guide to Aviation Medical Examiners does not disqualify right bundle branch blocks unless they are "newly acquired". New right bundle branch blocks require evaluation with radionuclide stress test, since standard stress tests are uninterpretable. In most cases, they are benign and pilots may fly with this finding.

Because the left sided conducting system has dual bundles, it is possible to get a left "hemiblock" of the anterior or posterior bundle. The new onset of a left bundle branch block may represent an early warning sign of coronary artery disease. If found on an FAA ECG, it is disqualifying until underlying heart disease is excluded.

Bradyarrhythmias and Heart Blocks-Sick Sinus Syndrome

Sick Sinus Syndrome (SSS) is not a single ECG finding, but rather a constellation of findings that indicate a failing sino-atrial node (the natural pacemaker) and the atrio-ventricular node (natural back-up pacemaker). SSS is characterized by very slow and very rapid heart rates (tachy-brady syndrome), irregular heart rates and a variety of symptoms in individuals. Symptoms may range from fainting, dizziness, chest pain and skipping beats. People with SSS may experience strokes, heart attacks and sudden death. The treatment for SSS is implanting a cardiac pacemaker. See American Family Physician for an excellent article and information handout on the subject.

Tachyarrhythmias-Pre-Excitation Syndrome - Wolff-Parkinson-White (WPW)

The most common syndrome that predisposes people to tachyarrhythmias is termed WPW syndrome. It is caused by the presence of by-pass electrical conduction pathways around the AV node. This signal is characterized by an upsloping "delta wave" on the ECG just prior to the QRS complex. Normally, the electrical signal to the ventricles dissipates and the next signal originates from the SA node. In WPW, the electrical discharge of the ventricles is conducted back through the by-pass tracts and around the AV node to set up what is termed a retrograde re-entrant arrhythmia. These tend to cause very fast arrhythmias. In 5% of WPW, the signals travel from the atria around the AV node through the by-pass tracts to the ventricles. The QRS complex is widened and the rate is also fast.

Several treatment options exist for people with WPW. Many individuals with WPW will not have any arrhythmia and do not require any treatment. The FAA Guide to Aviation Medical Examiners does not disqualify pilots with WPW who have not had a significant arrhythmia from holding any class of medical certificate. Those with arrhythmias will require control of the condition before medical certification.

The first treatment is with oral medications to slow electrical conduction across the by-pass tracts. These medications include beta blockers, calcium channel blockers, quinidine or flecanide. A second option involves ablation, or destruction, of the by-pass tract using a radiofrequency catheter. If successful, this procedure offers a potential permanent cure to WPW caused arrhythmias, usually without the need for medications. Complications of the procedure are rare, but may require placement of a pacemaker. FAA medical certification is possible with both treatment options.

Tachyarrhythmias-Atrial Fibrillation and Atrial Flutter

The most common arrhythmia in pilots requiring an FAA mandated cardiovascular evaluation is atrial fibrillation. Up to 2 million Americans are afflicted with atrial fibrillation each year. Approximately 4% of the adult population will experience atrial fibrillation in their lifetime. In this phenomenon, the upper chambers of the heart (atria) fibrillate, or quiver, rather than contracting sequentially. The AV node receives multiple inputs from many locations in the atria and sends irregular and frequent signals to the ventricles to contract. If the signals are transmitted rapidly, the resultant ventricular rate is very rapid and blood flow to the body is reduced because the left ventricle contracts before it can fill with blood.

The ECG representation of atrial fibrillation is the absence of a distinct P wave and "irregularly irregular" (random timing of heart beats) QRS complexes. An individual may note a very irregular heart rate, usually somewhat fast. In more serious cases, an individual may get lightheaded, have extreme fatigue, feel extreme anxiety, have chest pain or lose consciousness. Atrial fibrillation also puts and individual at risk for clots forming in the heart and causing strokes when they break loose into the brain.

Atrial flutter is very similar to atrial fibrillation, but is distinguished by a very rapid atrial rate (about 300 beats per minute) and a variable ventricular response. The ventricular response may be regular or irregular and frequently has a rate of about 150 beats per minute. The clinical implications and symptoms of atrial fibrillation and flutter are very similar.

Tachyarrhythmias-Atrial Fibrillation and Atrial Flutter-Treatment

Atrial fibrillation (AF) and flutter can be treated in several ways, often depending on associated heart conditions, tolerance of the arrhythmia and response to medications. Each of the treatment options is acceptable for waiver by the FAA, once control of the arrhythmia and exclusion of underlying heart disease are documented. An editorial on treatment strategies for atrial fibrillation in available in the May 10, 2001 issue of the New England Journal of Medicine. Also see an excellent article in American Family Physician "Acute Management of Atrial Fibrillation: Part I. Rate and Rhythm Control" July 15, 2002 and an editorial May 15, 2004 on Management of Newly Detected Atrial Fibrillation and the Practice Guidelines on the same subject for the most current evidence based medicine on the subject.

         Spontaneous Conversion

The first treatment option is to allow the atrial fibrillation to spontaneously convert to a normal sinus rhythm. Many instances of atrial fibrillation are short-lived, minutes to hours, and then return to a normal state. Often no medication is required to sustain the normal rhythm.

         Pharmacological Cardioversion

A second procedure is termed pharmacological cardioversion. Treatment with single doses of intravenous or oral forms of medication may convert AF to NSR. If this treatment is successful, often long term medication for control is not required as above. For the individual with recurrent bouts of AF, many medications can be used to control this rate and/or the rhythm. (see Medications below)

         Electrical Cardioversion

If the AF results in a very fast ventricular rate, an individual may experience lightheadedness, dizziness, loss of consciousness, chest pain or a heart attack. In these instances, there is a sense of urgency in conversion to a normal rhythm to eliminate or reduce symptoms. The use of direct electrical current, with or without medication, is the fast way to return the heart to a normal rhythm. This procedure is called electrical cardioversion. Situations requiring electrical cardioversion usually are treated with long term medication to suppress future episodes of AF. The FAA requires a three-month observation period following electrical cardioversion before returning to flying duties.

         Pre-Conversion Anticoagulation

At times, the individual with AF may not experience significant symptoms with the condition , or may not convert to NSR with medications, but have a controlled ventricular rate (less than 90-100) with the use of alternate medications. In these situations, the recommended course of treatment may be short-term (several weeks) anticoagulation with a blood thinning mediation, usually Coumadin, while pursuing an investigation of possible provocative factors. The reason for anticoagulation is to prevent clots from forming in blood stagnating in the atria. These blood clots could break loose and travel to the brain causing a stroke or to the lungs (pulmonary embolus).

Once achieving adequate anticoagulation and the documentation of the absence of any atrial clots (thrombi), an elective electrical cardioversion is done under controlled circumstances. With the use of anti-arrhythmic medications before the cardioversion, one or two electrical shocks may be enough to achieve a normal sinus rhythm in a previously refractive AF. If the NSR is sustained for several weeks on anti-arrhythmic mediation, the anticoagulation is discontinued and blood clotting times return to normal in one to two weeks.

         Atrial Fibrillation with Anticoagulation

Occasionally, all of the above treatment options fail to convert the AF to NSR. Three additional options exist. If the heart rate can be maintained at normal rates (60-80 bpm range) with medication, permanent anticoagulation to reduce the risk of strokes and emboli may be necessary. Because the anti-clotting medication, Coumadin, is very sensitive to many foods and medications, regular monitoring of the blood thinning effects is necessary. The laboratory reports followed are the prothrombin time (PT) or International Normalized Ratio (INR) with the dose of Coumadin adjusted to keep the PT/INR in a range of two to three times greater than that of the normal individual who is not anticoagulated.

Even those people who convert from atrial fibrillation to normal sinus rhythm are often placed on aspirin, a weak anticoagulant, designed to reduce the risk of stroke if the atrial fibrillation were to recur. This decision of whether to use aspirin or Coumadin depends on the risk factors present in the individual with atrial fibrillation. See an excellent article in American Family Physician Acute Management of Atrial Fibrillation: Part II. Prevention of Thromboembolic Complications July 15, 2002 for more specifics.

         Ablation

Mapping the electrical conduction pathways of the heart is increasingly common in the evaluation of arrhythmias. The electrical procedure, termed an electrophysiologic (EP) study, involves the use of a wire catheter inserted into the blood vessels of the inner thigh and guided into the heart. If an accessory tract, or alternate pathway, that may conduct electrical signal abnormally through the heart is discovered, the electrophysiologist will attempt to eliminate the pathway. The accessory tract is initially stimulated to determine if the stimulation will trigger an arrhythmia. If the arrhythmia is "inducible’, a radiofrequency ablation of the tract may be possible. A successful ablation procedure permanently eliminates one potential source of the arrhythmia by inducing an electrically dead area in the heart, analogous to a road block for the arrhythmia. Not all ablation attempts eliminate the arrhythmia, but those that do generally allow the individual to discontinue use of anti-arrhythmic mediation. The FAA currently requires a three-month observation period following ablation before requesting a Special Issuance medical certificate.

         Pacemaker

A third alternative treatment to suppress symptomatic arrhythmias is to insert a pacemaker. The electrical pacemaker "over drives" the heart to beat at a fixed rate, making it less susceptible to the multiple stimuli originally causing the arrhythmia. This technique employed with increasing frequency, and is potentially waiverable by the FAA. A comprehensive review of the subject of pacing and defibrillation for atrial arrhythmias was published in the New England Journal of Medicine in June 2002, Current Concepts: Implantable Devices for the Treatment of Atrial Fibrillation, J.M. Cooper et al.

Some newer pacemakers have an Automatic Internal Cardiac Defibrillator as an elective component of the device. Current FAA policy does not allow certification for any rhythm if an AICD is used, no matter how good the control. This policy is being reviewed, and to date there are a handful of certified cases.

         Maze Procedure

A recent development in the treatment of refractory, symptomatic atrial fibrillation is a surgical approach called the Maze procedure. This open heart surgery involves making a long incision in the heart and sewing it back together. The healing incision blocks the irregularly conducted heart beats to stop the atrial fibrillation. A newer form of the Maze procedure does not include open-heart surgery, but uses a radiofrequency ablation catheter to achieve the same results. The FAA has granted waivers to pilots who have undergone the Maze procedure to control atrial fibrillation successfully.

Medications to Control Atrial Arrhythmias

Several categories of medications are used to control rates of arrhythmias or suppress the arrhythmias. In most cases, the same medication used to control atrial fibrillation may be used to control other atrial arrhythmias or supraventricular tachycardias.

Digoxin, from the foxglove or digitalis plant, slows conduction of electrical signals across the AV node, thus giving a slower ventricular rate in atrial fibrillation. Digoxin may also suppress the atrial fibrillation. Digoxin may obscure the ECG interpretation of a plain stress test, thus leading to the possibility of a radionuclide stress test to rule out underlying coronary heart disease as a cause of the atrial fibrillation.

Another class of mediation that slows the ventricular heart rate in atrial fibrillation, but does not suppress the fibrillation, is beta-blockers. These include propranolol (Inderal) and metoprolol (Lopressor).

This class of medication is sometimes used in combination with digoxin to control the ventricular rate and eliminate most symptoms of AF that have not responded to pharmacological or chemical cardioversion attempts.

Most people who experience atrial fibrillation that does not spontaneously convert are offered one of several classes of anti-arrhythmic medications. Some commonly used medications include mexilitene, flecanide, amiodorone, sotalol, verapamil and diltiazem.

The goal for these medications is to sustain a normal sinus rhythm after chemical or electrical cardioversion. Often, if an individual has episodes of AF, but is free of any further recurrences for 6-12 months, the medication may be discontinued. After stopping the medication, an individual is monitored closely for further occurrence. If there are no further episodes, the anti-arrhythmic medication is permanently discontinued. Recurrences trigger resumption of the medication, usually on a permanent basis.

The FAA Aeromedical Certification Division does not dictate what medication regimens must be used in individual cases to qualify for a waiver. All treatment decisions remain between the pilot and treating physician. The FAA does not even require an evaluation by a cardiologist, although specialists may be able to arrange evaluations more conveniently than other physicians without immediate access to testing equipment. Assuming documentation of the arrhythmia control and the absence of other types of hear disease is complete, FAA follow-up reports can easily be completed by most primary care physicians. The overwhelming majority of pilots who experience uncomplicated atrial fibrillation can expect clearance by the FAA after a complete evaluation and continued medical certification in the future.

Tachyarrhythmias-Ventricular Arrhythmias

Like atrial arrhythmias, ventricular arrhythmias generally represent the non-coordinated beating of heat muscle resulting in inefficient pumping of blood through the heart. Unlike most atrial arrhythmias, ventricular arrhythmias are generally very serious and may have life threatening implications. Other than the second and third degree heart blocks, previously noted, there are two basic types of ventricular arrhythmias.

Tachyarrhythmias-Ventricular Arrhythmias-Ventricular Tachycardia

Ventricular tachycardia (VT or V Tach) is the rapid beating of the heart at rates greater than 100 beats per minute, paced by a ventricular source rather than the SA node or atria. The QRS complex of the ECG is wide (greater than 0.12 seconds) and often inverted from the standard pattern. Some people may survive short periods of VT (up to several minutes), but blood flow to the body and brain is rapidly compromised followed by loss of consciousness in most sustained episodes. Short bursts of VT (several seconds duration), frequently represents strings of consecutive PVCs, that may spontaneously revert to NSR. However, VT may degenerate into ventricular fibrillation, a rapidly fatal condition.

Tachyarrhythmias-Ventricular Arrhythmias-Ventricular Fibrillation

Ventricular fibrillation (VF or V fib) is the usual mechanism for loss of consciousness and death in "heart attacks." The treatment for VF is rapid (within 3-4 minutes) electrical countershock back into a more life sustaining rhythm. Following successful countershock, immediate stabilization with oxygen, anti-arrhythmic medication and treatment of the underlying cause, is required. People who are successfully resuscitated from VF are termed "sudden cardiac death survivors."

The most common underlying cause of VF is coronary artery disease (see VFS section on this topic). Other causes include electrocution, hypoxia and other forms of heart disease including Arrhythmogenic Right Ventricular Dysplasia. In correctable causes of VF, the risk of sudden cardiac death can be minimized.

The traditional, long term treatment for ventricular arrhythmia involve correcting the underlying cause and preventing future occurrence with medication. After an appropriate observation period following successful correction of the cause, many pilots may be returned to flying through the Special Issuance provisions of the FAR 67.401 on medication.

One increasingly common "treatment" for ventricular arrhythmias is the surgical placement of an Automatic Internal Cardiac Defibrillator, or AICD. This implanted device monitors the rhythm with sensors on the heart. If a ventricular arrhythmia is sensed, the AICD delivers a shock directly to the heart muscle through two "paddles" implanted on the heart. The shock is designed to reset the heart electrical state so that a sinus rhythm can take over. If no spontaneous rhythm is generated, the AICD works with a pacemaker to attempt to generate a life-sustaining rhythm. AICDs can be "interrogated" periodically to see if any abnormal rhythms have occurred, whether shocks were delivered and whether the pacer was required. The March 21, 2002 issue of the New England Journal of Medicine has both a review and an editorial on the use of AICDs.

The current FAA policy does not permit AICDs for any class of certification, nor is any major change in this policy anticipated in the foreseeable future. This non-certification policy for pilots with AICDs is true even for pilots who have had the devices placed prophylactically, but never discharged, as in conditions such as Arrhythmogenic Right Ventricular Dysplasia (ARVD). As previously noted, however, there have been a select few certifications in exceptional cases.

Tachyarrhythmias-Ventricular Arrhythmias-asystole

A third type of abnormal ventricular rhythm is asystole, the absence of any rhythm or heart beat. This condition is rapidly fatal in the absence of CPR and usually is seen in the seconds before death in an unsuccessful attempt at resuscitating other ventricular arrhythmias. FAA certification is not relevant.

FAA Evaluation of Arrhythmias

Overall, the FAA has a relatively liberal policy of certifying pilots with many types of arrhythmias, excepting those with AICDs. Most treatments, including coronary revascularization, anti-arrhythmic medications and pacemakers, may be considered for Special Issuance medical certification by the FAA. After stabilization with treatment prescribed by the pilot’s treating physician, submission of complete documentation to the FAA is critical for favorable certification decisions. Periodic follow-up reports are routinely required for pilots maintained on anti-arrhythmic medications or with pacemakers.

The FAA requires any pilot with a history of atrial and ventricular arrhythmias to complete a cardiac evaluation before a certification (waiver) decision is considered. Favorable certification decisions result when the arrhythmia is well controlled or eliminated and no evidence of other heart disease exists. The evaluation is relatively standard for all types of arrhythmias.

The routine evaluation required by the FAA involves completing the tests in the FAA Specifications for Cardiovascular Evaluation, FAA Form 8500-19. The documentation should include an evaluation of any cardiac history, risk factors for cardiovascular disease, a focused physical examination and laboratory studies. Risk factors for heart arrhythmias that can be eliminated, such as stimulants, medications, caffeine, tobacco, alcohol and herbal products (ma huang/ephedra) found in many weight loss products, should be halted. The lab studies include a fasting blood sugar, cholesterol, triglycerides, electrolytes and a complete blood count. Because hyperthyroidism is a relatively common cause of arrhythmias, laboratory studies of thyroid hormones is routine. Other labs tests may be indicated based on historical or physical factors.

Cardiac specific studies required include an echocardiogram to exclude structural heart abnormalities, as well as clots. After the arrhythmia is controlled, an exercise stress test and a 24-hour Holter monitor are required. The stress test (treadmill) detects evidence of coronary artery disease as a possible cause of the arrhythmia. If the stress test is abnormal, further, more definitive studies are required such as a radionuclide stress test or coronary angiography. (See VFS Section on Coronary Artery Disease).

The Holter monitor should demonstrate control of the atrial fibrillation or other arrhythmias, either by elimination of the abnormal rhythm for the routine 24-hour period or by continuous control of the rate of ventricular beats to less than approximately 100 bpm (60-80 bpm is the desirable range). Resting heart rates greater than 100 bpm and non-resting heart rates greater than 130-140 as disqualifying for certification, as are pauses longer than 3.0 seconds.

If anticoagulated with blood thinners such as Coumadin, control of the PT or INR to 2-3 times normal on at least three consecutive reports is required for certification. It may take several months to find a dosage schedule of Coumadin to keep the PT in the therapeutic range. For continued certification, 80% of INRs need to be in the therapeutic range.

Pilots treated with electrical cardioversion may be considered for Special Issuance Authorizations after a three-month observation period.

Pilots undergoing radiofrequency ablation of an arrhythmia-inducing electrical tract can be considered for waiver after a three month observation period and a Holter monitor showing no further arrhythmias. Generally, follow-up reports are not required after initial waiver.

If a pilot has a pacemaker, monthly pacer checks for two months will also be required before the FAA will consider recertification. Occasionally, an electrophysiologic study, or electrical map of the heart, may be conducted by a cardiologist in refractory cases of arrhythmias. If done, the FAA will request the results of these studies. Other tests may be required depending on the nature of the condition. Follow up of pacemaker surveillance depends of the type of pacer (single or dual chamber) and age of the pacemaker.

Go to the 'FAA Guide to Aviation Medical Examiners' on heart conditions provides additional information on evaluations required.

Pilots with arrhythmias may obtain the required documentation from their treating physicians and mail it to the FAA Aeromedical Certification Division at:

Aeromedical Certification Division, AAM-300

Civil Aeromedical Institute, FAA

P.O. Box 26080

Oklahoma City, OK 73126-0080

However, without careful review, direct submittal often can result in significant delays in certification while the FAA asks for clinical clarification. Often well-meaning specialists who are not trained in aerospace medicine fail to address all the aeromedically important aspects of a particular case. As a result, the case is returned without action pending further documentation, or worse the pilot receives a potentially unwarranted denial.