Cardiac Arrhythmias Flashcards
Sinus Bradycardia: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Results from slowing of the SA Node.
Etiology: May result from;
Increased Parasympathetic (Vagal) Tone.
Intrinsic disease of the SA Node
Drug Effects (digitalis, beta-blockers, calcium channel blockers)
Normal Finding in Healthy Well Conditioned Persons
Rules of Interpretation: (Lead II) Rate: <60, Rhythm: R-R Regular, Pacemaker Site: SA Node
P Wave: Normal and Upright
PR Interval: Normal 0.12-0.2 second and constant
QRS Complex: Normal 0.04-0.12 second
Clinical Significance: Decreased rate can cause decreased cardiac output, hypotension, angina, or CNS symptoms. Especially true for rates lower than 50bpm. Slow rate may also lead to atrial or ventricular ectopic rhythms. In a healthy athlete this may be normal.
Treatments: Generally unessecary unless signs of poor perfusion (acute altered mental status, hypotension, ongoing chest pain, or other signs of shock). Oxygen. If there are signs of poor perfusion prepare for transcutaneous pacing. Consider 0.5mg bolus of Atropine, repeat every 3-5min until you have achieved a satisfactory rate or have given 3.0mg total. If atropine fails consider transcutaneous cardiac pacing, dopamine or epi infusions.
Sinus Tachycardia: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Results from an increased rate of SA node discharge.
Etiology: May Result from;
Exercise, Fever, Anxiety, Hypovolemia, Anemia, Pump failure, Increased Sympathetic Tone, Hypoxia, Hyperthyroidism
Rules of Interpretation: (Lead II)
Rate: >100, Rhythm: Regular, Pacemaker Site: SA Node, P waves: Normal/Upright, PR Interval: Normal, QRS: Normal
Clinical Significance: Often benign. In some cases it is a compensatory mechanism for decreased stroke volume. If greater than 140bpm cardiac output may fall due to ventricular filling time (preload) is inadequate. Increased rates=increased O2 demand for the heart and thus increase possible ischemia or infarct in diseased hearts. Prolonged sinus tach accompanying Acute Myocardial Infarction is often an ominous sign suggesting cardiogenic shock.
Treatments: Directed at underlying cause. Hypovolemia, fever, hypoxia, or other causes should be corrected.
Sinus Arrhythmia: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Sinus arrhythmia often results from a variation in the R-R Interval.
Etiology: It is often a normal finding and is sometimes related to the respiratory cycle and changes in intrathoracic pressure. Common in children. Pathologically it can be caused by enhanced vagal tone.
Rules of Interpretation: Rate: 60-100 (Varies w/Respirations), Rhythm: Irregular, Pacemaker site: SA Node. P Wave: Upright and Normal, PR Interval: Normal, QRS: Normal
Clinical Significance: It is a normal variant, particularly in the young or elderly.
Treatment: Typically Non-required.
Sinus Arrest: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Occurs when the SA Node fails to discharge for a brief period resulting in short periods of cardiac standstill. One or more of the PQRST complexes will be missing. Can persist until pacemaker cells lower in the system discharge (escape beats) or until the SA node resumes discharge. Because the node fails to fire the R-R interval following the dropped beat will vary ie. the pause will not be a multiple of the previous R-R interval.
Etiology: Ischemia of the SA Node, Digitalis toxicity, Excessive Vagal tone, Degenerative Fibrotic Disease
Rules of Interpretation: Rate: Normal to Slow Depending on the Frequency & Duration of the arrest. Rhythm: Irregular, Pacemaker Site: SA Node, P Wave: Upright & Normal, PR Interval: Normal, QRS: Normal
Clinical Significance: Frequent/Prolonged episodes may compromise cardiac output resulting in syncope and other issues. Always the danger of complete cessation of the SA Node activity. Usually, an escape rhythm develops; occasionally cardiac standstill can result.
Treatment: If asymptomatic: observe until changes occur. If signs of poor perfusion (Altered mental status, chest pain, hypotension or other signs of shock) prepare for transcutaneous pacing. Consider bolus of 0.5mg Atropine. Repeat every 3-5min to a max of 3mg. If atropine fails consider transcutaneous pacing or a dopamine or epi infusion.
Sinus Block: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Also called Sinus Exit Block occurs when the sinus node fires on time but the impuse is blocked before it exits the sinus node. This results in a pause that varies in length depending on how many sinus beats are blocked. Because the SA Node fires the R-R intervals after the last beat will be constant ie. the pause will be a multiple of the previous R-R interval.
Etiology: Ischemia of the SA node, Digitalis Toxicity, Excessive Vagal Tone, Degenerative Fibrotic Disease.
Rules of Interpretation: Rate: Normal to Slow Depending on the Frequency & Duration of the arrest. Rhythm: Regular, Pacemaker Site: SA Node, P Wave: Upright and Normal, PR Interval: Normal, QRS: Normal
Clinical Significance: Frequent/Prolonged episodes may compromise cardiac output resulting in syncope and other issues. Always the danger of complete cessation of the SA Node activity. Usually, an escape rhythm develops; occasionally cardiac standstill can result.
Treatment: If asymptomatic: observe until changes occur. If signs of poor perfusion (Altered mental status, chest pain, hypotension or other signs of shock) prepare for transcutaneous pacing. Consider bolus of 0.5mg Atropine. Repeat every 3-5min to a max of 3mg. If atropine fails consider transcutaneous pacing or a dopamine or epi infusion.
Sinus Pause: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Occurs when the sinus node fails to discharge for a brief period resulting in a missing PQRST. Differs from sinus arrest in that only ONE beat is missing. Because the node fails to fire the R-R interval following the dropped beat will vary ie. the pause will not be a multiple of the previous R-R interval.
Etiology: Ischemia of the SA Node, Digitalis Toxicity, Excesive Vagal Tone, Degenerative Fibrotic Disease.
Rules of Interpretation: Rate: Normal to Slow Depending on the Frequency & Duration of the arrest. Rhythm: Irregular, Pacemaker Site: SA Node, P Wave: Upright & Normal, PR Interval: Normal, QRS: Normal.
Clinical Significance: Frequent/Prolonged episodes may compromise cardiac output resulting in syncope and other issues. Always the danger of complete cessation of the SA Node activity. Usually, an escape rhythm develops; occasionally cardiac standstill can result.
Treatment: If asymptomatic: observe until changes occur. If signs of poor perfusion (Altered mental status, chest pain, hypotension or other signs of shock) prepare for transcutaneous pacing. Consider bolus of 0.5mg Atropine. Repeat every 3-5min to a max of 3mg. If atropine fails consider transcutaneous pacing or a dopamine or epi infusion.
Sick Sinus Syndrome: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Technically not an arrhythmia but a combination of arrhythmias. Occurs when the SA Node is ischemic or diseased. Characterized by wild swings in HR often moving from profound Brady to severe Tachycardia and back. Sinus blocks are also commonly seen with SSS. Because the node fails to fire the R-R interval following the dropped beat will vary ie. the pause will not be a multiple of the previous R-R interval.
Etiology: Ischemia of the SA Node, Digitalis Toxicity, Degenerative Fibrotic Disease.
Rules of Interpretation: Rate: Extremely Variable, Rhythm: Irregular, Pacemaker Site: SA Node, P Wave: Upright & Normal, PR Interval: Normal, QRS: Normal.
Clinical Significance: Frequent/Prolonged episodes may compromise cardiac output resulting in syncope and other issues. Always the danger of complete cessation of the SA Node activity. Usually, an escape rhythm develops; occasionally cardiac standstill can result.
Treatment: If asymptomatic: observe until changes occur. If signs of poor perfusion (Altered mental status, chest pain, hypotension or other signs of shock) begin transcutaneous pacing or a dopamine or epi infusion.
What are the Arrhythmias Originating in the SA Node
Sinus Bradycardia Sinus Tachycardia Sinus Arrhythmia Sinus Arrest Sinus Block Sinus Pause Sick Sinus Syndrome
What are the Arrhythmias Originating in the Atria?
Wandering Atrial Pacemaker Multifocal Atrial Tachycardia Premature Atrial Contractions Paroxysmal Supraventricular Tachycardia Atrial Flutter Atrial Fibrillation
Wandering Atrial Pacemaker: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Is also called Ectopic Tachycardia. Is the passive transfer of pacemaker sites from the sinus node to other latent pacemaker sites in the atria and AV junction. Often more than one pacemaker site will be present causing a variation in the R-R interval and P wave morphology.
Etiology: A variant of sinus arrhythmia, a normal phenomenon in the very young or elderly, Ischemic Heart disease, Atrial Dilation.
Rules of Interpretation: Rate: Usually Normal, Rhythm: Slightly Irregular, Pacemaker site: Varies among the SA Node, Atrial Tissue, and the AV Junction. P Wave: Morphology changes from beat to beat, P waves may dissapear. PR interval: Varies; maybe less than 0.12, normal or greater than .20, QRS: Normal
Clinical Significance: Usually has no detrimental effects. Occasionally it can be a precursor of other atrial arrythmias such as A-Fib. Sometimes it indicated digitalis toxicity.
Treatment: If asymptomatic; observe for changes. If symptomatic consider Adenosine.
Multifocal Atrial Tachycardia: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Usually seen in acutely ill patients. It is a wandering pacemaker rhythm with a rate greater than 100. Significant pulmonary disease is seen in ~60% of these patients. Certain meds used to treat pulmonary disease (beta agonists/theophylline) may worsen the arrhythmia. Three different P waves are noted, indicating various ectopic foci.
Etiology: Pulmonary disease, Metabolic Disorders (Hypokalemia), Ischemic heart disease, Recent Surgery.
Rules of Interpretation: Rate: >100, Rhythm: Irregular, Pacemaker Site: Ectopic Sites in Atria. P Wave: Organized, discrete non-sinus P waves w/atleast 3 different forms. PR Interval: Varies, QRS: Maybe .2 depending on the AV node’s refractory status when the impulse reaches it.
Clinical Significance: Frequently these patients are acutely ill. This arrhythmia may indicate a serious underlying illness.
Treatment: Treatment of underlying medical issue usually resolves the arrhythmia. Specific antiarrhythmic therapy is usually not required.
Premature Atrial Contractions: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Result from a single electrical impulse originating in the atria outside the SA Node which inturn causes a premature depolarization of the heart before the next expected sinus beat. Because it depolarizes the atrial syncytium, this impulse also depolarizes the SA Node interrupting the normal cadence. This creates a noncompensatory pause in the underlying rhythm.
Etiology: Use of caffeine, nicotine or alcohol. Sympathomimetic Drugs. Ischemic Heart Disease, Hypoxia, Digitalis Toxicity, Idiopathic Causes.
Rules of Interpretation: Rate: Depends on Underlying Rhythm. Rhythm: Depends on the Underlying Rhythm, usually regular except for the PAC. Pacemaker site: Ectopic Focus in the Atrium. P Wave: The P wave of the PAC differs from the P wave of the underlying rhythm. It occurs earlier than the next expected P wave and may be hidden in the preceding T Wave. PR Interval: Usually normal, can vary with the location of the ectopic focus. Ectopic foci near the SA node will have a PRI of .12 or more. Ectopic foci near the AV node will have a PRI of .12 or less. QRS: usually Normal. Maybe greater than .12 if the PAC is abnormally conducted through partially refractory ventricles. In some cases the ventricles are refractory and will not depolarize in response to the PAC. In these cases the QRS maybe absent.
Clinical Significance: Isolated PAC’s are of minimal significance. Frequent PAC’s may indicate organic heart disease and may precede other atrial arrhythmias.
Treatment: If asymptomatic: Observe. If patient is hypoxic and symptomatic administer O2 to correct hypoxia. Contact medical direction as needed.
Paroxysmal Supraventricular Tachycardia: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Occurs when rapid Atrial depolarization overrides the SA Node. Often occurs in paroxysm w/ sudden onset, may last minutes to hrs, terminates abruptly. May be caused by increased automaticity of a single atrial focus or by reentry phenomenon at the AV node. Paroxysmal means it starts and stops. Often they are not seen on the rhythm strip. In order to diagnose PSVT the paroxysms must be seen.
Etiology: May occur at any age, NOT associated w/ heart disease. May be precipitated by stress, overexertion, smoking or caffeine. It is sometimes associated with atherosclerotic cardiovascular disease and rheumatic heart disease. PSVT is rare in patients w/ MI. It can occur w/ accessory pathway conduction such as Wolf-Parkinson-White syndrome.
Rules of Interpretation: Rate: 150-250 Rhythm: Regular except at onset and termination. Pacemaker Site: In the Atria outside SA Node. P Wave: Atrial P wave differs slightly from sinus P waves. May be buried in preceding T Waves. PR Interval: Usually Normal, however it can vary w/ length of ectopic pacemaker. Ectopic pacemakers near SA node have PRI close to .12. Ectopic pacemakers near the AV node will have PRI of .12 or less. QRS: Normal
Clinical Significance: Young pts. w/ good cardiac reserves may tolerate PSVT well for short periods. Patients often sense PSVT as palpitations. Rapid rates can cause reduction in cardiac output due to inadequate ventricular filling. The reduced diastolic phase can also compromise coronary artery perfusion. PSVT can precipitate angina, hypotension or congestive heart failure.
Treatment: If pt. is stable obtain a 12 lead and IV access.
Asymptomatic: Obtain a 12ld, Observe
Symptomatic with NO signs of hypo-perfusion: Vagal Maneuvers. Medications (Adenosine)
Symptomatic WITH signs of hypo-perfusion: Synchronized Cardioversion
Supraventricular Tachycardia: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Refers to tachycardias that originate above the ventricles. Pacemaker site is often difficult to determine due to rate. The rapid rate often makes P waves indiscernible. Pacemaker site can be in the SA node, the atria or the AV junction.
Etiology: Use of caffeine, nicotine, or alcohol. Cocaine. Sympathomimetic Drugs, Ischemia heart disease, Hypoxia, Digitalis Toxicity, Idopathic causes.
Rules of Interpretation: Rate: 150-250, Rhythm: Regular except at onset/termination. Pacemaker site: in Atria outside SA node. P Wave: May be impossible to see due to rapid rate. PR Interval: Usually normal but can vary depending on Pacemaker location. Closer to SA .12 closer to AV less than .12. QRS: Normal
Clinical Significance: Young pts. w/good cardiac reserves may tolerate STV for short periods. May feel palpitations. Rapid rates can cause reduction in cardiac output. Reduced diastolic phase can compromise coronary artery perfusion. SVT can precipitate angina, hypotension, or CHF.
Atrial Flutter: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Results from a rapid atrial reentry circuit and an AV node that physiologically cannot conduct all impulses through to the ventricles. The AV junction may allow impulses in a 1:1 (Rare) 2:1, 3:1, 4:1 ratio or greater resulting in a discrepancy between atrial and ventricular rates. The AV block may be consistent or variable.
Etiology: It may occur in normal hearts but it is usually associated w/ organic disease. It rarely occurs as the direct result of an MI. Atrial dilation which occurs w/ CHF is a cause of A. Flutter.
Rules of Interpretation: Rate: Atrial Rate is 250-350, Ventricular rate varies w/ the ratio of AV conduction. Rhythm: Atrial Rhythm is regular, Ventricular rhythm is usually regular but can be irregular if the block is variable. Pacemaker Site: In the atria outside the SA node. P Waves: Flutter (F) waves are present reselmbling a saw tooth or picket fence pattern. The pattern is often difficult to id in a 2:1 flutter. However, if the rate is ~150 suspect 2:1 flutter.
Clinical Significance: A. Flutter w/normal ventricle rates is normally well tolerated. Rapid ventricular rates may compromise cardiac output and result in symptoms. A. Flutter often occurs in conjunction with A. Fib and is referred to as A. Fib-Flutter.
Treatment: If stable obtain 12lead and IV access.
1. Pharmacological Therapy: Consider rate control w/ Diltiazem or Beta-blockers if the patient is unstable, ie. chestpain, altered mental status, hypotension or shock.
- Electrical Therapy: Syncronized cardioversion if rate is more than 150. If time allows sedate patient and apply syncronized DC countershock of 50-100 joules (or biphasic equivalent).
Atrial Fibrillation: Give Description, Etiology, Rules of Interpretation, Wave Descriptions, Clinical Significance and Treatments
Description: Results from multiple areas of reentry within the atria or from ectopic foci bombarding the AV node that physiologically cannot handle all of the incoming impulses. AV conduction is random and highly variable.
Etiology: May be chronic and is often associated with underlying heart disease such as rheumatic heart disease, atherosclerotic heart disease or CHF. Atrial dialtion occurs with CHF and often causes atrial fibrillation.
Rules of Interpretation: Rate: Atrial rate is 350-750bpm (cannot be counted). Ventricular rate varies greatly depending on conduction through the AV node. Rhythm: Irregularly regular. Pacemaker site: Numerous ectopic foci in the atria. P Waves: none discernible. Fibrillation (f) waves are present indicating chaotic atrial activity. PR Interval: None QRS: Normal
Clinical Significance: In A. Fib the atria fail to contract and the atria kick is lost. Thus reducing cardiac output by 20-25%. There is frequently a pulse deficit (a difference between the apical and peripheral pulse rates). If ventricular response is normal and the patient is on digitalis A. Fib is usually well tolerated. If the ventricular rate is less than 60 cardiac output can fall. Suspect digitalis toxicity in patients taking digitalis w/ A Fib and ventricular rates less than 60.
Treatment: If pt. is stable obtain a 12 lead ECG and establish IV access.
- Pharmacological Therapy: Consider rate control with diltazem or beta blockers.
If patient is unstable, altered mental status, hypo tension, chest pain, other signs of shock.
- Electrical Therapy: Used synchonized cardioversion if the rate is greater than 150. If time allows sedate and apply DC countershock of 50-100 joules or biphasic equivalent.
Which Arrhythmia is associated with Pulmonary disease?
Multifocal Atrial Tachycardia
