Arrhythmias therapeutic tutorial Flashcards
what is the atrial fibrilation
A common supraventricular tachyarrhythmia, caused by uncoordinated atrial activation resulting in an irregular ventricular response. Patients are often asymptomatic but have an irregular pulse on physical examination. When present, symptoms usually include palpitations and lightheadedness. Patients with atrial fibrillation are at an increased risk of stroke and other thromboembolic complications.
what are the ECG findings of Afib?
- -Irregularly irregular RR intervals (The time interval between two successive ORS complexes varies unpredictably.)
- -P-waves are indiscernible
- -Tachycardia
- -Narrow QRS complex (< 0.12 seconds)
what are the cardiovascular risk factors of Afib?
- -increasing age
- -Hypertension
- -Diabetes mellitus
- -Smoking
- -Obesity
- -Sleep apnea
what are the Intrinsic cardiac disorders that increase the risk of Afib?
–Coronary artery disease
–Valvular heart disease (especially mitral valve disease)
–Congestive heart failure (CHF)
–Pre-excitation tachycardia (e.g., Wolff-Parkinson-White syndrome)
–Sick sinus syndrome (tachycardia-bradycardia syndrome)
–Cardiomyopathies
Pericarditis
what are the Intrinsic cardiac disorders that increase the risk of Afib?
1) Pulmonary disease: COPD, pulmonary embolism, pneumonia
2) Hyperthyroidism
3) Catecholamine release and/or increased sympathetic activity
- -Stress: sepsis, hypovolemia, post-surgical state (especially following cardiac surgery), hypothermia
- -Pheochromocytoma
- -Cocaine, amphetamines
4) Electrolyte imbalances (hypomagnesemia, hypokalemia)
5) Drugs: e.g., adenosine, digoxin
6) Holiday heart syndrome: irregular heartbeat classically triggered by excessive alcohol consumption, but also sometimes by moderate consumption, stress, or lack of sleep
7) Chronic kidney disease
what is the holiday heart syndrome?
This syndrome acquired its name because it typically occurs after binge drinking, which often coincides with vacations or holidays. The association with alcohol consumption is why this syndrome is not confined to the elderly, but may also be found in young adults. Patients with holiday heart syndrome usually have paroxysmal AF.
what is the AF with Rapid ventricular response?
AF with a ventricular rate > 100 bpm (tachycardic AF)
what are the antiarrhythmic drugs?
Group of drugs that are used to restore sinus rhythm in patients presenting with cardiac arrhythmias, as well as to prevent recurrent arrhythmias. Antiarrhythmic agents are classified into 5 classes according to their electrophysiological effect on the myocardium (i.e., sodium channel blocker, beta blocker, potassium channel blocker, calcium channel blocker, and others). Because all antiarrhythmic drugs are potentially proarrhythmic, they should be administered under ECG monitoring.
what are the class I antiarrhythmic drugs?
- -Na+ channel blockers
1) A Prolong action potential —Quinidine, Disopyramide
2) B Shorten action potential—Lidocaine,
3) C No effect on action potential –Flecainide, Propafenone
what are the class II antiarrhythmic drugs?
–Beta-blockers—Metoprolol, Bisoprolol
what are the class III antiarrhythmic drugs?
–K+ channel blockers—Amiodarone, Dronedarone, Sotalol, Dofetilide
what are the class IV antiarrhythmic drugs?
–Ca++ channel blockers–Verapamil, Diltiazem
what are the treatment strategies of AF?
- -Rhythm control (conversion of atrial fibrillation/flutter to sinus rhythm)
- -Heart rate control (slowing of heart rate) are possible treatment strategies
what is the rate control?
A mainstay of treatment of atrial fibrillation to normalize the ventricular heart rate. Drugs used for rate control include beta-blockers (e.g., esmolol, propranolol, metoprolol) and nondihydropyridine calcium channel blockers (e.g., diltiazem, verapamil).
what is the rhythm control?
A treatment strategy for atrial fibrillation to restore sinus rhythm and prevent atrial remodeling. Includes elective synchronized cardioversion and the use of antiarrhythmics, such as flecainide, propafenone, ibutilide, dofetilide, or amiodarone.
in unstable AF, the rate or rhythm control is the priority?
- -rhythm
- -Unstable AF: emergent electrical cardioversion
- -If AF does not terminate, cardioversion should be repeated with increased shock energy after adjusting the electrodes’ position.
what are the indications for rate vs rhythm control?
- -Elderly patients (Because elderly individuals have decreased clearance of antiarrhythmic drugs and are at increased risk of proarrhythmias (arrhythmias caused by antiarrhythmic therapy).)
- -Failure of rate-control strategy to control symptoms, Younger patients (Rhythm control strategies may be preferable among younger individuals in order to prevent ventricular remodeling.)
what are the contraindications of rate vs rhythm control?
- -AF due to pre-excitation syndromes (The use of rate control drugs such as digoxin, amiodarone, calcium channel blockers and/or beta blockers depresses AV node conduction. In patients with WPW syndrome, AV blockade can lead to increased conduction through the aberrant pathway and thus precipitate ventricular tachycardia or ventricular fibrillation.)
- -Long-standing persistent AF (Atrial modeling occurs within 6 months of the onset of AF and any advantage that would have been gained by the use of the rhythm control strategy is lost.)
what are the first-line drugs used for rate control?
- -1st choice: beta blockers (esmolol, propanolol, metoprolol) OR nondihydropyridine calcium channel blockers (diltiazem, verapamil)
- -2nd choice: digoxin
- -3rd choice: dronedarone, amiodarone (Possesses both rate- and rhythm-control mechanisms)
what are the indications of Beta-blockers and CCBs in AF?
Beta-blockers are the ones most commonly used for rate control followed by nondihydropyridine calcium channel blockers. Beta-blockers are preferred when AF is due to hyperthyroidism. Beta-blockers should be avoided in a patient with COPD. nondihydropyridine calcium channel blockers (ndhp CCB) cannot be used among patients with decompensated heart failure (LV systolic dysfunction/low ejection fraction) because they are negatively inotropic and lead to worsening of heart failure. ndhp CCBs may, however, be used in heart failure with preserved normal LV systolic function
what are the indications of digoxin in AF?
Digoxin is preferred as first-line therapy in patients with decompensated HF when beta blockers are contraindicated.
what is the second line measure of rate control in AF?
- -AV nodal ablation and implantation of a permanent ventricular pacemaker
- -The pacemaker should ideally be implanted 4–6 weeks before AV nodal ablation. AV nodal ablation is an irreversible procedure and eliminates the need for rate control drugs. However, it leads to life long dependence on a pacemaker and should therefore not be performed without first attempting rate control with drug therapy. Maximum benefit is seen among elderly patients, patients with tachycardia-induced cardiomyopathy, and those refractory to rate control medications. A biventricular pacing system is recommended for AF patients with decompensated heart failure.
What additional therapy patients with AF require during admission to the hospital?
–Anticoagulant Therapy to be considered in all patients in atrial fibrillation because of the stroke risk. Options include;
1)IV heparin followed by oral warfarin (Vitamin K Antagonist)
or
2)Novel/New Oral Anti-Coagulants (NOAC drugs with lower bleeding risks)
–Direct thrombin inhibitors
*Dabigatran,
–Factor Xa Inhibitors
*Apixaban
*Rivaroxaban
*Edoxaban
In the presence of Atrial Fibrillation, the decision to anti-coagulate is based on…
- -Stroke Risk – CHA2DS2VASc Score
- -Bleeding Risk – HAS-BLED Score
–Anticoagulation is commenced where
stroke risk is moderately high, and
–bleeding risk is low.
