Arrhythmia PDF

. Arrhythmia  Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, Are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a re...

. Arrhythmia  Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, Are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a resting heart rate that is too slow – below 60 beats per minute – is called bradycardia. Some types of arrhythmias have no symptom.  Symptoms when present, may include -- palpitations or feeling a pause between heartbeats. --In more serious cases, there may be lightheadedness, passing out, shortness of breath or chest pain. --While most cases of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure. Others may result in sudden death.  categories Arrhythmias are often categorized into four groups: 1-extra beats, 2-supraventricular tachycardias, 3-ventricular arrhythmias and 4-bradyarrhythmias. 1-Extra beats include: -premature atrial contractions, -premature ventricular contractions and -premature junctional contractions. 2-Supraventricular tachycardias include: -atrial fibrillation, -atrial flutter and -paroxysmal supraventricular tachycardia. 3-Ventricular arrhythmias include : -ventricular fibrillation and -ventricular tachycardia. 4-Bradyarrhythmias are due to sinus node dysfunction or atrioventricular conduction disturbances.  Arrhythmias may occur at any age but are more common among older people. Arrhythmias may also occur in children; however, the normal range for the heart rate varies with age. Ventricular fibrillation (VF) showing disorganized electrical activity producing a spiked tracing on an electrocardiogram (ECG)  Treatments Many arrhythmias can be effectively treated. Treatments may include medications, medical procedures (such as inserting a pacemaker), and surgery. Medications for a fast heart rate may include beta blockers, or antiarrhythmic agents such as procainamide, which attempt to restore a normal heart rhythm. This latter group may have more significant side effects, especially if taken for a long period of time.  Pacemakers are often used for slow heart rates. Those with an irregular heartbeat are often treated with blood thinners to reduce the risk of complications. Those who have severe symptoms from an arrhythmia or are medically unstable may receive urgent treatment with a controlled electric shock in the form of cardioversion or defibrillation.  Symptomatic Bradycardia treatment unstable (Note: Unstable = hypotension, acutely altered mental status, signs of shock, ischemic chest discomfort, acute HF.) treatment A-atropine 0.5 mg every 3–5 minutes (maximum dose 3 mg). B. If atropine fails, - transcutaneous pacing, - dopamine 5–20 mcg/kg/minute, -or epinephrine 2–10 mcg/minute.  Symptomatic Tachycardia treatment 1. If unstable: synchronized cardioversion. 2. If stable: determine whether QRS complex is narrow or wide. A. Narrow complex tachycardia (QRS less than 120 milliseconds): Usually atrial arrhythmias 1. Regular ventricular rhythm: Supraventricular tachycardia (SVT) or sinus tachycardia likely. (Treatment): ---Vagal maneuvers or ----adenosine 6-mg intravenous push, followed by a 20-mL saline flush, then a 12-mg intravenous push (may repeat once). ---Rapid push followed by elevation of arm to increase circulation --- Larger doses may be needed in patients taking theophylline, caffeine. ---- Initial dose should be reduced to 3 mg in patients taking dipyridamole or carbamazepine and in patients after( heart transplantation), as well as when the drug is being given by (central access). ----Use adenosine cautiously in severe CAD. ---- Adenosine should not be given to patients with asthma. ----- Do not give adenosine for unstable or for irregular or polymorphic wide complex tachycardias because it may cause degeneration to VF. - If vagal maneuvers or adenosine fails to convert paroxysmal SVT, -- calcium channel blockers (CCBs) --or β-blockers can be used. If Wolff-Parkinson-White syndrome, avoid verapamil, diltiazem, and digoxin. 2. Irregular ventricular rhythm: AF (or possibly atrial flutter) (a) If hemodynamically stable General management should focus on control of the rapid ventricular rate. (TREATMENT) Usually nondihydropyridine CCBs (diltiazem, verapamil) or β-blockers; digoxin is sometimes useful. Rate is acceptable if it is less than 110 beats/minute at rest in asymptomatic persistent AF.  (b) If hemodynamically unstable, synchronized cardioversion recommended. ====Patients with AF for more than 48 hours are at high risk of cardioembolic events and should not be immediately cardioverted if stable. =====Transesophageal echocardiography before cardioversion is an alternative strategy to ensure the absence of left atrial clot. ===== Risk of thromboembolic event surrounding cardioversion (both pharmacologic and electrical) is greatest within the first 10 days.  (f) Cardioversion 1- If AF for up to 7 days, either elective direct current conversion or chemical cardioversion A- Flecainide, dofetilide, propafenone, ibutilide, or amiodarone B- Digoxin and sotalol are not recommended and may be harmful. C- Disopyramide, quinidine, and procainamide are less effective. 2- If AF greater than 7 days, administer either elective direct current conversion or chemical cardioversion with dofetilide, amiodarone, or ibutilide.  B. Wide complex tachycardia (QRS greater than 120 milliseconds): Usually ventricular arrhythmias 1. regular Ventricular tachycardia (VT) a- Consider adenosine only if regular and monomorphic. b- Intravenous procainamide, amiodarone (or sotalol); lidocaine second line c- Avoid procainamide and sotalol if prolonged QTc. 2. Polymorphic (irregular) VT: (torsade de pointes) Induced primarily when the QTc interval is greater than 500 milliseconds a- If unstable, polymorphic (irregular) VT requires immediate defibrillation. b- If stable, intravenous magnesium (Mg2+) 1- to 2-g intravenous bolus (maximum 16 g/24 hours) may be given.  QT-prolonging medications Withdrawal of QT-prolonging medications, correction of low Mg2+ or K+ levels (1) Class I and III antiarrhythmic drugs (2) Assess for drug interactions by cytochrome P450 3A4 (e.g., azole antifungals, erythromycin). (3) Assess for other QTc-prolonging drugs such as: haloperidol, ziprasidone, droperidol, promethazine, macrolide and quinolone antibiotics, tricyclic antidepressants, or drugs contraindicated with dofetilide such as sulfamethoxazole/trimethoprim or thiazides.  Vaughan-Williams AAD Classes Class/Ion Affected agent Class I /Na+ channel blockers Ia (intermediate) Disopyramide quinidine, procainamide Ib (fast) Lidocaine, mexiletine, phenytoin Ic(slow) Flecainide, propafenone encainide class II β-Blockers Metoprolol, esmolol, atenolol Class III K+ channel blockers sotalol Amiodarone, dronedarone dofetilide ibutilide Class IV Ca2 channel blockers Diltiazem, verapamil  Long term Management of Ventricular Arrhythmias 1. Nonsustained VT a. Asymptomatic i. Infrequent ventricular ectopic beats ii. No treatment other than reassurance is needed for patients without SHD or inherited arrhythmia disorder. b- symptomatic A. β-Blockers i. Considered mainstay therapy ii. Effective in suppressing ventricular ectopic beats and in reducing SCD ---in a spectrum of cardiac disorders in patients with and without HF. B- non-dihydropyridine CCBs an alternative in pts without SHD C- AAD (amiodarone, flecainide, mexilitine, propaphenone, sotalol) may be added.  2- sustained VT -immediate defibrillation for pulseless VT -synchronized cardioversion for VT with pulse -ICD (implantable cardioverter defibrillator) for SHD(structural heart disease) with b- blockers,amiodarone , sotalol  Treatment of Arrhythmias in Special Patient Populations 1. Heart failure a. Avoid class Ia and class Ic agents. b. Amiodarone and dofetilide (used for atrial arrhythmias only) have a neutral effect on mortality in patients with LV dysfunction after MI. c. Dronedarone (used in atrial arrhythmias only) is contraindicated in patients with symptomatic HF with recent decompensation necessitating hospitalization or NYHA class IV symptoms; risk of death was doubled in these patients. 2. Acute MI a. Avoid class Ia and class Ic agents. b. Class Ia medications: Increased mortality in post-MI survivors c. Amiodarone and dofetilide (used for atrial arrhythmias only) have a neutral effect on mortality in patients with LV dysfunction after an MI.  Drug-Induced Arrhythmias 1. Drug-induced QT prolongation a. Discontinue offending agent if QT prolongation is significant (i.e., greater than 450 milliseconds). b. Ensure proper renal and hepatic dosing adjustments. c. Review electrolyte abnormalities and thyroid function tests. d. Ensure that all electrolytes are maintained at critical levels: K+ greater than 4 mmol/L and less than 5 mmol/L and Mg++ greater than 2 mg/dL. 2. Drug induced Bradycardia or atrioventricular block a. β-Blocker, CCB, digoxin b. Administer antidote if appropriate (e.g., calcium for CCB toxicity). 3. Review for drug interactions. Antiarrhythmic agents have drug interactions that may cause significant outcomes. Thank you