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Arrhythmia Management - Tintinalli's
Terms in this set (55)
Some variation in the sinoatrial (SA) node discharge rate is common; however, if the variation exceeds ____ second between the longest and shortest intervals, sinus arrhythmia is present.
What are the ECG characteristics of sinus arrhythmia are (3)?
(a) normal sinus P waves and PR intervals, (b) 1:1 atrioventricular (AV) conduction, and (c) variation of at least 0.12 second between the shortest and longest P-P interval
Sinus arrhythmias are affected primarily by what?
Sinus arrhythmias are most commonly found in what age group?
Children and young adults.
Disappear with advancing age
What treatment is required for sinus arrhythmias?
Premature atrial contractions
What are the ECG characteristics of PACs (3):
(a) the ectopic P wave appears sooner (premature) than the next expected sinus beat; (b) the ectopic P wave has a different shape and direction; and (c) the ectopic P wave may or may not be conducted through the AV node
What are PACs associated with?
Stress, fatigue, alcohol use, tobacco, coffee, COPD, digoxin toxicity, CAD, and may occur after adneosine-converted PSVT
What will patients complain of with PACs?
Palpitations or an intermittent "sinking" or "fluttering" feeling in the chest
What is the emergency department treatment of PACs (3)?
1. Discontinue precipitating drugs (alcohol, tobacco, or coffee) or toxins
2. Treat underlying disorders (stress or fatigue)
3. PACs that produce significant symptoms or initiate sustained tachycardias can be suppressed with agents such as β-adrenergic antagonists (eg, metoprolol 25 to 50 milligrams PO 3 times daily), usually in consultation with a follow-up physician
What are the ECG characteristics of sinus bradycardia are (3)?
(a) normal sinus P waves and PR intervals, (b) 1:1 AV conduction, and (c) atrial rate slower than 60 beats/min
Sinus bradycardia represents a suppression of the sinus node discharge rate, usually in response to what 3 categories of stimuli?
(a) physiologic (vagal tone), (b) pharmacologic (calcium channel blockers, β-blockers, or digoxin), and (c) pathologic (acute inferior myocardial infarction [MI], increased intracranial pressure, carotid sinus hypersensitivity, hypothyroidism, or sick sinus syndrome)
Sinus bradycardia usually does not require specific treatment unless what (2)?
(a) the heart rate is slower than 50 beats/min and (b) there is evidence of hypoperfusion
What is the emergency department treatment of sinus bradycardia when it is indicated (5)?
1. Transcutaneous cardiac pacing is the only Class I treatment for unstable patients.
2. Atropine is a Class IIa treatment for symptomatic bradycardia
3. Epinephrine may be used if external pacing is not available
4. Internal pacing will be required in the patient with symptomatic recurrent or persistent sinus bradycardia due to sick sinus syndrome
5. Isoproterenol may be effective but carries a risk of increased myocardial oxygen demand and hypotension
What are the ECG characteristics of sinus tachycardia (2)?
(a) normal sinus P waves and PR intervals and (b) an atrial rate usually between 100 and 160 beats/ min
Sinus tachycardia is a response to what 3 categories of stimuli?
(a) physiologic (pain or exertion), (b) pharmacologic (sympathomimetics, caffeine, or bronchodilators), or (c) pathologic (fever, hypoxia, anemia, hypovolemia, pulmonary embolism, or hyperthyroidism)
What is the emergency department treatment of sinus tachycardia?
Diagnose and treat the underlying condition
SVT arises from (2)?
(a) impulse reentry or (b) an ectopic pacemaker above the bifurcation of the His bundle
The reentrant variety is the most common
In patients with atrioventricular bypass tracts, reentry usually occurs in which direction? (orthodromic/antidromic)
Ectopic SVT usually originates where?
In the atria
With an atrial rate of 100-250 bpm
Ectopic SVT may be seen in which patients (5)?
Patients with acute MI, chronic lung disease, pneumonia, alcohol intoxication, or digoxin toxicity
What is the emergency department treatment for an unstable patient in SVT?
What are some vagal maneuvers that may be used in the emergency department as initial treatment of the stable patient in SVT (3)?
Diving reflex (immerse face in cold water)
Carotid sinus massage
Which drug is first-line treatment for WPW-associated SVT with a narrow QRS complex (orthodromic conduction)?
Which drug classes may be used in patients with narrow-complex SVT (orthrodromic conduction) for chemical cardioversion (3)?
Calcium channel blockers (diltiazem, verapamil)
Beta blockers (esmolol, metoprolol, propranolol)
How should patients with wide-complex SVT (antidromic conduction across accessory pathway) be approached?
As presumed VT
Patients with this type of tachycardia are at risk for rapid ventricular rates and degeneration into VF; therefore, agents that preferentially block the AV node such as β-blockers, calcium channel blockers, and digoxin should not be used
Which drug is used to treat stable patients with wide-complex SVT (antidromic conduction across the accessory pathway)?
What are the ECG characteristics of atrial flutter (3)?
(a) a regular atrial rate between 250 and 350 beats/min;
(b) "saw tooth" flutter waves directed superiorly and most visible in leads II, III, and aVF; and
(c) AV block, usually 2:1, but occasionally greater or irregular
Atrial flutter is most commonly seen in which patients (7)?
Patients with ischemic heart disease as well as CHF, acute MI, pulmonary embolus, myocarditis, blunt chest trauma, and digoxin toxicity.
Why should you consider anticoagulation in patients with an unclear time of onset or duration of atrial flutter longer than 48 hours before conversion to sinus rhythm?
Which anticoagulant is indicated?
Due to increased risk of atrial thrombus and embolization
What is the treatment of an unstable patient in atrial flutter?
Synchronized cardioversion (50-100 J)
Which drug should be used for rate control in a patient with atrial flutter?
Alternative agents: verapamil, metoprolol, digoxin
Which drug should be used in a patient with atrial flutter AND impaired cardiac function (EF <40%)?
What are the ECG characteristics of Afib (2)?
(a) fibrillatory waves of atrial activity, best seen in leads V1, V2, V3, and aVF; and (b) an irregular ventricular response, usually between 170 to 180 beats/min in patients with a healthy AV node
Afib can be idiopathic or may be found in association which which disorders (6)?
Longstanding hypertension, ischemic heart disease, rheumatic heart disease, alcohol use ("holiday heart"), COPD, and thyrotoxicosis
Anticoagulation is required for how long before cardioversion in patients with Afib for longer than 48 hours duration or in patients with an uncertain time of onset?
T/F The emergency department treatment of Afib is the same as atrial flutter
What are the ECG characteristics of MAT (3)?
(a) 3 or more differently shaped P waves;
(b) changing PP, PR, and RR intervals; and
(c) atrial rhythm usually between 100 and 180 beats/min
MAT is found most often in elderly patients with decompensated COPD but it also may be found in which other patients (4)?
Patients with CHF, sepsis, methylxanthine toxicity, or digoxin toxicity
Junctional escape beats occur in patients with what disorders (3)?
Sinus bradycardia, SA node exit block, or AV block
Sustained junctional escape rhythms are seen with what disorders (5)?
CHF, myocarditis, acute MI (esp inferior), hyperkalemia, digoxin toxicity
What drug is indicated in an unstable patient with a sustained junctional escape rhythm?
In unstable patients not response to the above drug, what treatment is indicated?
Transcutaneous or transvenous pacing
PVCs occur in most patients with which two conditions?
Ischemic heart disease and acute MI
Other common causes of PVCs include digoxin toxicity, CHF, hypokalemia, alkalosis, hypoxia, and sympathomimetic drugs
What is the emergency department treatment of PVCs (3)?
1. Stable patients require no treatment
2. Patients with 3 or more PVCs in a row should be managed as VT
3. For hemodynamically unstable patients with PVCs, consider lidocaine
Accelerated indioventricular rhythm (AIVR) is found most commonly in which two conditions?
An acute MI or in the setting of reperfusion after successful thrombolysis
What is the treatment of AIVR?
No treatment is necessary
What are the ECG characteristics of VT (4)?
(a) a wide QRS complex,
(b) a rate faster than 100 beats/min (most commonly 150 to 200 beats/min),
(c) a regular rhythm, although there may be some initial beat-to-beat variation, and
(d) a constant QRS axis
What are the two most common causes of VT?
Ischemic heart disease and acute MI
Other etiologies include hypertrophic cardiomyopathy, mitral valve prolapse, drug toxicity (digoxin, antiarrhythmics, or sympathomimetics), hypoxia, hypokalemia, and hyperkalemia
In general how would all wide complex tachycardias be treated?
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