Cardiology #6 (Rhythms) Flashcards
What is the normal rate in a normal sinus rhythm?
60-100 bpm
Sinus arrhythmia increases with _____ and decreases with ______
Increases with inspiration
Decreases with expiration
What is sinus tachycardia defined as?
Increased heart rate > 100 bpm originating from the sinus node
Although sinus tachycardia is normal in young children and infants, as well as response to emotional or physical stress, what are some causes that are abnormal?
- fever
- hypoxia
- infection
- hypoglycemia
- anxiety
- shock
- cocaine
Treatment for sinus tachycardia
- Treat underlying cause
- However, BB (Metoprolol) are used if tachycardia with ACS
What is sinus bradycardia?
Decreased HR < 60 bpm originating from sinus node
What are some causes of pathologic sinus bradycardia?
- BB, CCB
- Digoxin
- Carotid Massage
- Hypothyroidism
Treatment for sinus bradycardia, both symptomatic and asymptomatic
Symptomatic: Atropine; if not responsive to Atropine, use Epinephrine or Transcutaneous pacing
Asymptomatic: no treatment needed if physiologic (young athletes, nausea, vomiting)
What is sick sinus syndrome?
Combination of sinus arrest with alternating paroxysms of tachycardia and bradycardia
What are the etiologies of sick sinus syndrome?
- Sinus node fibrosis (MC)
- Older age
- Medications
Management for sick sinus syndrome
- Stable: symptoms are transient, may not require therapy
- Unstable: Atropine (first line). Transcutaneous pacing
- Long-term: permanent pacemaker definitive. AICD if alternating between tachycardia and bradycardia
What is seen on ECG in a patient with a 1st degree AV block?
-Prolonged PR interval (> 0.20 seconds) + all P waves are followed by QRS complexes
What is the treatment for a patient with a first-degree AV block?
- Asymptomatic: no treatment
- Symptomatic: Atropine (first line), epinephrine
- Pacemaker is definitive if persistent and severe
Explain what an ECG shows in a patient with a Mobitz I - Wenkebach 2nd degree AV block.
-Progressive PRI lengthening –> dropped QRS
What should be given for a Wenkenbach AV block?
Atropine, Epinephrine +/- pacemaker
What is special about a Mobitz II 2nd degree AV block?
Constant/Prolonged PRI –> dropped QRS
Treatment for a Mobitz II block
Atropine or temporary pacing
Progression of a Mobitz II to a ____ is common, so what treatment is definitive?
3rd degree AV block
Permanent pacemaker
What are etiologies of a Mobitz I 2nd degree AV block?
- Inferior Wall MI
- AV nodal blocking agents (BB, Digoxin, CCB)
- Myocarditis due to Lyme
- cardiac surgery
- Hyperkalemia
A Mobitz II 2nd degree AV block is rarely seen in patients without
structural heart disease (Myocarditis, myocardial ischemia, endocarditis)
What is a 3rd degree AV block?
AV dissociation = no atrial impulses reach the ventricles, so the atrial activity is independent of the ventricular activity
Causes of a 3rd degree AV block
- Inferior wall MI
- AV nodal blocking agents (BB, CCB, Digoxin)
- Myocarditis (due to Lyme)
- Cardiac Surgery
- Endocarditis
ECG of a 3rd degree AV block
-regularly P-P intervals and regular R-R intervals, but they are not related to each other. Patients are often bradycardia.
Treatment for 3rd degree AV block if the patient is symptomatic
Transcutaneous pacing often followed by permanent pacemaker placement (Definitive)
What is true about patients with A-fib and Atrial Flutter?
-Increased risk of thrombus formation that can lead to cerebral and/or systemic embolization (stroke)
What are some symptoms of unstable atrial flutter?
refractory chest pain, hypotension, AMS
Describe the ECG in a patient with atrial flutter
-Sawtooth atrial waves usually around 300 beats per minute but no discernible P waves
Management of a patient with stable atrial flutter
- Vagal maneuvers
- BB or CCB (Diltiazem, Verapamil)
Management of a patient with unstable atrial flutter
Direct current (synchronized) cardioversion
In a patient with atrial flutter, what is the definitive treatment?
Radiofrequency catheter ablation
MC chronic arrythmia
A-fib
Risk factors for A-fib
Men > Women Increasing age Whites > blacks Drug or alcohol use Medications Genetics Thyroid disorders
Unstable A-fib provides symptoms such as
Hypotension, refractory chest pain, AMS
Describe an ECG of A-fib
Irregularly irregular rhythm with fibrillary waves (no discrete P waves)
-Often > 250 bpm
With A-fib, what is Ashman’s phenomenon?
occasional aberrantly conducted beats (wide QRS) after short R-R cycles
Management of a patient with STABLE A-fib
-Rate control with BB OR CCB (Diltiazem, Verapamil)
Management of a patient with UNSTABLE A-fib
-Direct current (synchronized) Cardioversion
What is the long-term treatment for a patient with A-fib
Rate control usually preferred over rhythm control for long-term management
- Direct cardioversion or pharm cardioversion
- Radiofrequency catheter ablation
- Anticoagulation (in patients with a risk for embolization)
Cardioversion is most successful when performed within ______ after onset of A-fib
7 days
What is needed BEFORE cardioversion to ensure there are no atrial clots?
Echocardiogram
Anticoagulation is the treatment for A-fib, but is dependent on the time A-fib has been present. Explain.
AF > 48 hours: anticoagulation for at least 3 weeks before cardioversion or a TEE-guided approach with abbreviated anticoagulation
AF < 48 hours: elective cardioversion, but anticoagulation is recommended beforehand
Anticoagulation must be continued for how long after cardioversion?
4 weeks
The CHA2DS2-VASc score is used to determine risk for embolization in patients with A-fib. Chronic oral anticoagulation (Warfarin or Novel oral anticoagulants) are required for those with what score?
2 or greater
What are the components of the CHA2DS2 VASc criteria and their point values?
Congestive Heart Failure: 1 Hypertension: 1 Age 75 or more: 2 DM: 1 Stroke, TIA, Thrombus: 2 Vascular Disease (prior MI, PAD): 1 Age 65-74: 1 Sex (Female): 1
Non-Vitamin K antagonist oral anticoagulants (NOAC) are usually preferred over Warfarin due to lower rates of major bleeding and lower risk of ischemic stroke (do not have to check INR and less drug interactions). Name some of these medications.
- Dabigatran (binds and inhibits thrombin)
- Rivaroxaban, Apixaban, Edoxaban (factor Xa inhibitors)
When would Warfarin be the preferred anticoagulant?
- In patients with severe chronic kidney disease
- Contraindications to NOAC (HIV patients, on anti epileptic medications)
What is the normal INR goal of a patient on Warfarin?
goal of 2-3
Dual anti platelet therapy with what two medications is reserved for patients who cannot be treated with anticoagulation (for reasons OTHER than bleeding risk)?
Aspirin + Clopidogrel
