Atrial Flutter
Atrial Flutter is a dysrhythmia, which is the result of a flawed reentry circuit within the atria. It is often described as resembling a sawtooth or picket fence. These flutter waves should not be confused for P-waves. The AV node is a wonderful protective mechanism. Imagine the atria depolarizing at a rate of 250 to 350 bpm. If all of these atrial depolarizations were conducted down into the ventricle, the patient’s ventricles would likely begin to fibrillate. Think of the AV node as the central train station where numerous train tracks merge. The central station only lets some of the trains through to avoid congestion. The AV node helps to protect the ventricles by only allowing some of the atrial depolarizations to conduct down through the bundle of His into the bundle branches and on to the ventricles. When the ventricular rate is < 100 bpm, we call this “controlled atrial flutter”. If the ventricular rate is > 100 bpm, it is labeled “uncontrolled atrial flutter”. Since the ventricles always have more time to fill during diastole when the HR is <100,our goal is to have controlled atrial flutter. This can often be accomplished with drug therapy. In the setting of atrial flutter, coordinated contraction of the atria is absent. The patient has therefore,lost their atrial kick with potential loss of cardiac output and lower blood pressure.
Causes
• Acute or chronic cardiac disorder, mitral or tricuspid valve disorder, cor pulmonale,pericarditis
• Post MI complication (usually transient)
• Hyperthyroidism
• Alcoholism
• Post cardiac surgery (usually transient)
ECG Criteria
1) Heart Rate: Atrial rate is 250-350 bpm. Ventricular rate varies according to AV node conduction.
2) Rhythm: Atrial regular; ventricular may be regular or irregular (again, depending on AV node conduction).
3) P-waves: Absent. Only flutter or saw tooth looking wave forms.
4) PR Interval: Not applicable.
5) QRS Width: < 0.12 seconds.
Atrial Fibrillation
Atrial fibrillation (often called “a. fib” or “atrial fib”) may result from multiple areas of re-entry within the atria or from multiple ectopic foci. The atrial electrical activity is very rapid(approximately 400 bpm), but each electrical impulse results in the depolarization of only a small is let of atrial myocardium rather than the whole atrium. As a result, there is no contraction of the atria as a whole. Since there is no uniform atrial depolarization, there is no P-wave. The chaotic electrical activity does produce a deflection on the ECG, referred to as a fibrillatory wave.
Fibrillatory waves vary in size and shape and are irregular in rhythm. Fibrillatory waves look different from the sawtooth waves of atrial flutter. Transmission of these multiple atrial impulses into the AV node is thought to occur at random, resulting in an irregular rhythm. Some impulses are conducted into but not through the AV node (they are blocked within the AV node).Remember that the ventricular rhythm is always irregular in atrial fibrillation.When the ventricular rate is < 100 bpm, we call this “controlled atrial fibrillation”. If the ventricular rate is >100 bpm, it is labeled “uncontrolled atrial fibrillation”. Since diastolic filling is enhanced when the HR is <100, our goal is to have controlled atrial fibrillation. This can often be accomplished with drug therapy.
Atrial Flutter is a dysrhythmia, which is the result of a flawed reentry circuit within the atria. It is often described as resembling a sawtooth or picket fence. These flutter waves should not be confused for P-waves. The AV node is a wonderful protective mechanism. Imagine the atria depolarizing at a rate of 250 to 350 bpm. If all of these atrial depolarizations were conducted down into the ventricle, the patient’s ventricles would likely begin to fibrillate. Think of the AV node as the central train station where numerous train tracks merge. The central station only lets some of the trains through to avoid congestion. The AV node helps to protect the ventricles by only allowing some of the atrial depolarizations to conduct down through the bundle of His into the bundle branches and on to the ventricles. When the ventricular rate is < 100 bpm, we call this “controlled atrial flutter”. If the ventricular rate is > 100 bpm, it is labeled “uncontrolled atrial flutter”. Since the ventricles always have more time to fill during diastole when the HR is <100,our goal is to have controlled atrial flutter. This can often be accomplished with drug therapy. In the setting of atrial flutter, coordinated contraction of the atria is absent. The patient has therefore,lost their atrial kick with potential loss of cardiac output and lower blood pressure.
Causes
• Acute or chronic cardiac disorder, mitral or tricuspid valve disorder, cor pulmonale,pericarditis
• Post MI complication (usually transient)
• Hyperthyroidism
• Alcoholism
• Post cardiac surgery (usually transient)
ECG Criteria
1) Heart Rate: Atrial rate is 250-350 bpm. Ventricular rate varies according to AV node conduction.
2) Rhythm: Atrial regular; ventricular may be regular or irregular (again, depending on AV node conduction).
3) P-waves: Absent. Only flutter or saw tooth looking wave forms.
4) PR Interval: Not applicable.
5) QRS Width: < 0.12 seconds.
Atrial Fibrillation
Atrial fibrillation (often called “a. fib” or “atrial fib”) may result from multiple areas of re-entry within the atria or from multiple ectopic foci. The atrial electrical activity is very rapid(approximately 400 bpm), but each electrical impulse results in the depolarization of only a small is let of atrial myocardium rather than the whole atrium. As a result, there is no contraction of the atria as a whole. Since there is no uniform atrial depolarization, there is no P-wave. The chaotic electrical activity does produce a deflection on the ECG, referred to as a fibrillatory wave.
Fibrillatory waves vary in size and shape and are irregular in rhythm. Fibrillatory waves look different from the sawtooth waves of atrial flutter. Transmission of these multiple atrial impulses into the AV node is thought to occur at random, resulting in an irregular rhythm. Some impulses are conducted into but not through the AV node (they are blocked within the AV node).Remember that the ventricular rhythm is always irregular in atrial fibrillation.When the ventricular rate is < 100 bpm, we call this “controlled atrial fibrillation”. If the ventricular rate is >100 bpm, it is labeled “uncontrolled atrial fibrillation”. Since diastolic filling is enhanced when the HR is <100, our goal is to have controlled atrial fibrillation. This can often be accomplished with drug therapy.
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| Atrial Fibrillation |
Possible Causes
• Mitral valve disorders
• Rheumatic heart disease, MI, hypertension, coronary artery disease (CAD), heart failure,pericarditis.
• Chronic obstructive pulmonary disease (COPD)
• Digoxin toxicity
• Post cardiac surgery (usually transient)
ECG Criteria
1) Heart Rate: Atrial rate 350-400 bpm. Ventricular rate is variable
2) Rhythm: Ventricular rate is irregular (one of the hallmark signs of atrial fibrillation)
3) P-waves: Absent. Only atrial fibrillatory waves (or small looking bumps) are seen
4) PR Interval: Not applicablea
5) QRS Width: < 0.12 seconds
On the ECG, AF is described by the replacement of consistent P-waves by rapid oscillations or fibrillatory waves that vary in size, shape, and timing, associated with an irregular, frequently rapid ventricular response when atrioventricular (AV) conduction is intact. The ventricular response to AF depends on electrophysiological properties of the AV node, the level of vagal and sympathetic tone, and the action of drugs. Regular RR intervals are possible in the presence of AV block or interference due to ventricular or junctional tachycardia. In patients with electronic pacemakers, diagnosis of AF may require temporary inhibition of the pacemaker to expose atrial fibrillatory activity. A rapid, irregular, sustained, wide-QRS-complex tachycardia strongly suggests AF with conduction over an accessory pathway or AF with underlying bundle-branch block. Extremely rapid rates (over 200 bpm) suggest the presence of an accessory pathway. The picture below shows AF with fast ventricular rate.
• Mitral valve disorders
• Rheumatic heart disease, MI, hypertension, coronary artery disease (CAD), heart failure,pericarditis.
• Chronic obstructive pulmonary disease (COPD)
• Digoxin toxicity
• Post cardiac surgery (usually transient)
ECG Criteria
1) Heart Rate: Atrial rate 350-400 bpm. Ventricular rate is variable
2) Rhythm: Ventricular rate is irregular (one of the hallmark signs of atrial fibrillation)
3) P-waves: Absent. Only atrial fibrillatory waves (or small looking bumps) are seen
4) PR Interval: Not applicablea
5) QRS Width: < 0.12 seconds
On the ECG, AF is described by the replacement of consistent P-waves by rapid oscillations or fibrillatory waves that vary in size, shape, and timing, associated with an irregular, frequently rapid ventricular response when atrioventricular (AV) conduction is intact. The ventricular response to AF depends on electrophysiological properties of the AV node, the level of vagal and sympathetic tone, and the action of drugs. Regular RR intervals are possible in the presence of AV block or interference due to ventricular or junctional tachycardia. In patients with electronic pacemakers, diagnosis of AF may require temporary inhibition of the pacemaker to expose atrial fibrillatory activity. A rapid, irregular, sustained, wide-QRS-complex tachycardia strongly suggests AF with conduction over an accessory pathway or AF with underlying bundle-branch block. Extremely rapid rates (over 200 bpm) suggest the presence of an accessory pathway. The picture below shows AF with fast ventricular rate.
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| Atrial Fibrillation with Fast Ventricular Rate |
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