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Cardiology

Cardiology. SVT Algorithm Atrial Fibrillation/Atrial Flutter Pharmacology. SVT Algorithm Regular/Narrow-Complex Tachycardia. This algorithm is used for all patients with a heart rate of 150 or greater with narrow QRS complexes and pulses.

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Cardiology

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  1. Cardiology SVT Algorithm Atrial Fibrillation/Atrial Flutter Pharmacology

  2. SVT AlgorithmRegular/Narrow-Complex Tachycardia • This algorithm is used for all patients with a heart rate of 150 or greater with narrow QRS complexes and pulses. • Initial determination is whether the patient is Stable vs. Unstable. • 4 Parameters for unstable patients: • Altered Mental Status/ALOC • Hypotension • Ongoing Chest Pain • Other signs of shock (i.e. dyspnea, diaphoresis, etc.)

  3. SVT Algorithm • The difference in therapy between Stable and Unstable patients: • Stable Patients  pharmacology first. • Unstable Patients  electricity first. • The form of electricity is  Cardioversion • This will be covered in detail during the lab sessions.

  4. SVTStable Patient • Initiate oxygen therapy • Initiate an IV line • Obtain 12 lead ECG (if available) • Attempt Vagal/Valsalva Maneuvers • Drug of choice is: Adenosine. Can be given up to 3 times if needed. • 6 mg, rapid IVP, followed by a 20 ml bolus of NSS if no conversion… • 12 mg, rapid IVP, followed by a 20 ml bolus of NSS if no conversion… 3) 12 mg, rapid IVP, followed by a 20 ml bolus of NSS

  5. SVT Stable Patient • After Adenosine if the rhythm does NOT change, the next drug of choice is either a Calcium Channel Blocker or a Beta Blocker. • Calcium Channel Blockers: • Diltiazem (Cardizem): Calcium Channel Blocker of choice a) 15 to 20 mg (0.25 mg/kg) over 2 minutes, can be repeated in 15 minutes with 20-25 mg (0.35 mg/kg) b) If patient converts hang a drip (100mg/100ml) and run at 1 mg/minute.

  6. SVT Stable Patient • If choosing a Beta-Blockade administer as follows: • Metoprolol: 5mg q 5min, total 15minute • Atenolol: 5mg slow over 5min, repeat q10min • Propanolol: .1mg/kg slow IV push. Divide into 3 equal doses and administer q3min <= 1mg/min. • Esmolol: .5mg/kg over 5 min over 1 min, follow with 4 minute infusion at 50ug/kg • Labetalol: 10mg IVP over 2 min, may repeat or double q10 min. Total dose 150mg. ** use B-blockers with caution in pulmonary disease or CHF

  7. SVTStable Patient • If unsuccessful, consider expert consultation.

  8. SVTUnstable Patient • If the patient meets the parameters of being unstable, perform immediate SynchronizedCardioversion at the listed energy levels listed later in this lecture. Remember that unstable patients cannot perform a Vagal/Valsalva maneuver. • Remember to obtain IV access. • If patient is still conscious sedate (versed/valium).

  9. A-Fib/A-Flutter Irregular Narrow-Complex Tachycardia • Again treatment is reserved for those with heart rates above 150 with irregular narrow complex tachycardia. • Determine if the patient is stable vs. unstable. Using the same guides as for SVT. • If stable, consider expert consultation and if indicated control rate with: 1) Calcium Channel Blockers 2) Beta Blockers • If unstable, perform immediate synchronized cardioversion.

  10. Treatment Modalities • Adenosine • Calcium Channel Blockers • Beta Blockers • Synchronized Cardioversion

  11. Adenosine • Generic Name: Adenosine • Trade Name: Adenocard • Classification: Class IVb antiarrhythmic, endogenous nucleoside • How Supplied: 3 mg/ml

  12. AdenosineMechanism of Action • Found naturally in all body cells. • Rapidly metabolize in the blood vessels. • Slows sinus rate • Slows conduction time through AV node • Can interrupt reentry pathways through AV node • Can restore sinus rhythm in SVT

  13. AdenosineIndications • First line medication for most forms of narrow-QRS supraventricular tachycardia (SVT)

  14. AdenosineDosing (adult) • Peripheral IV dose: 6 mg rapid IV push over 1 to 3 seconds. If no response within 1 to 2 minutes administer 12 mg. May repeat 12 mg dose once in 1 to 2 minutes. Follow each dose immediately with a 20 ml NSS bolus. Recommended IV site is the antecubital fossa. Nothing lower. • Use the injection port nearest the hub of the IV catheter. Constant ECG monitoring is essential.

  15. Facial flushing Coughing/dyspnea, bronchospasm Nausea Headache Hypotension Chest pressure Lightheadedness Paresthesias Dysrhythmias at time of rhythm conversion Use with caution in patients with emphysema, bronchitis Avoid in patients with asthma Discontinue in any patient who develops severe respiratory difficulty AdenosinePrecautions

  16. AdenosineContraindications • Poison/drug-induced tachycardia • Asthma • 2nd or 3rd degree AV Block • Sick sinus syndrome (except in clients with a functioning artificial pacemaker) • Atrial flutter/atrial fibrillation • Ventricular tachycardia

  17. AdenosineSpecial Considerations • Must be injected into the IV tubing as fast as possible. Failure to do so may result in breakdown of the medication while still in the IV tubing. • Adenosine may cause fatal cardiac arrest, sustained ventricular tachycardia requiring resuscitation, and non-fatal MI. Transient or prolonged episodes of asystole have been reported with fatal outcomes in some cases. • If central line is in place may only require 3 mg for IV administration.

  18. AdenosineOnset of Action SECONDS!!!!!

  19. Calcium Channel Blockers • Generic/Trade Name: Verapamil (Calan, Isoptin, Verelan), Diltiazem (Cardizem) • Classification: Calcium channel blocker (calcium antagonist). • How Supplied: Verapamil – injection: 5mg/2ml Diltiazem – injection: 5 mg/ml monovial; 100 mg freeze-dried; powder for injection – 10 mg, 25 mg

  20. Calcium Channel BlockersMechanism of Action • Inhibit movement of calcium ions across cell membranes in the heart and vascular smooth muscle, resulting in: • Depressant effect on the heart’s contractile function (negative inotropic effect) • Slowed conduction through the AV node (negative dromotropic effect) • Dilation of coronary arteries and peripheral arterioles • Decreased myocardial oxygen demand

  21. Calcium Channel BlockersIndications • SVT • Patients with normal LV function (diltiazem Class I) • Patients with impaired LV function (diltiazem  Class IIb) • Atrial Tachycardia • Patients with normal LV function (diltiazem Class IIb) • Patients with impaired LV function (diltiazem  Class IIb)

  22. Calcium Channel BlockersIndications • Atrial flutter/fibrillation: for rate control • Patients with normal LV function (diltiazem, verapamil  Class I) • Patients with impaired LV function (diltiazem  Class IIb) • Pre-excited atrial fibrillation (WPW) 1) Patients with normal LV function (diltiazem, verapamil  Class III)

  23. Calcium Channel BlockersIndications • Junctional Tachycardia • Verapamil, diltiazem  Class indeterminate • Inappropriate Sinus Tachycardia 1) Verapamil, diltiazem  Class indeterminate

  24. Calcium Channel BlockersDosing Verapamil • 2.5 – 5 mg IV bolus over 2 minutes (administer over 3 to 4 minutes in elderly or if BP is within the lower range of normal). May repeat with 5 to 10 mg in 15 to 30 minutes (if no response and BP remains normal or elevated). • Maximum dose 20 mg

  25. Calcium Channel BlockersDosing Diltiazem • 15 to 20 mg (0.25 mg/kg) over 2 minutes. If needed, follow in 15 minutes with 20 to 25 mg (0.35 mg/kg) IV over 2 minutes. • Maintenance infusion 1 mg/min, titrated to heart rate.

  26. Calcium Channel BlockersPrecautions • Avoid calcium channel blockers in patients with wide-QRS tachycardia unless it is known with certainty to be supraventricular in origin. • Calcium channel blockers decrease peripheral resistance and can worsen hypotension. • IV calcium channel blockers and IV beta-blockers should not be administered together or in close proximity (within a few hours) – may cause severe hypotension.

  27. Wide-QRS tachycardia of uncertain origin Poison/drug induced tachycardias Digitalis toxicity (may worsen heart block) Atrial fibrillation/flutter with an accessory bypass tract (WPW) Severe CHF Sick sinus syndrome (bradycardia-tachycardia syndrome) except with a functioning ventricular pacemaker. Hypotension (SBP < 90 mmHg) Cardiogenic shock 2nd or 3rd degree AV block Calcium Channel BlockersContraindications

  28. Calcium Channel BlockersSpecial Considerations • Diltiazem depresses myocardial contractility to a lesser degree than verapamil and causes less hypotension. • During administration, monitor closely for hypotension and AV block.

  29. Calcium Channel BlockersOnset of Action • Verapamil IV: 2 to 5 minutes • Diltiazem IV: ½ to 1 hour

  30. Calcium Channel BlockersDurations • Verapamil IV: 2 hours • Diltiazem IV: 1 to 3 hours

  31. Calcium Channel BlockersDrug Interactions • Beta-blockers may have additive negative inotropic and chronotropic effects. • In some cases, coadministration of verapamil or diltiazem may prolong bleeding time. • Concurrent use of amiodarone and diltiazem can result in bradycardia and decreased cardiac output by an unknown mechanism. • Verapamil has bee found to significantly inhibit elimination of alcohol, resulting in elevated blood alcohol concentrations that may prolong the intoxicating effects of alcohol.

  32. Beta Blockers • Generic/ Atenolol (Tenormin) Trade Names: Esmolol (Brevibloc) Labetalol (Normodyne, Trandate) Metoprolol (Lopressor) Propranolol (Inderal) • Classification: Beta-blockers

  33. Beta Blockers • How Supplied: • Atenolol – injection: 5mg/10m • Esmolol – injection: 100 mg/10 ml single-dose vial • Labetalol – injection: 5 mg/ml in 20 ml ampule; 20, 40, 60 ml multi-dose vials • Metoprolol – injection: 1 mg/ml in 5 ml ampule • Propranolol – injection: 20 mg/5 ml unit-dose containers; 40 mg – 5 ml unit dose containers

  34. Beta BlockersMechanism of Action • Slows sinus rate • Depresses AV conduction • Reduces blood pressure • Decreases myocardial oxygen consumption • Reduces the incidence of dysrhythmias by decreasing catecholamine levels • Reduces risk of sudden death in patients with an acute coronary syndrome

  35. Beta BlockersIndications • Non-ST segment elevation MI or unstable angina (Class I) • Adjunctive agent with fibrinolytic therapy • To reduce incidence of VF in post-MI patients who did not receive fibrinolytics (atenolol, metoprolol, propranolol)

  36. Beta BlockersIndications • To slow the ventricular response in: (esmolol) • SVT (Class I) • Atrial fibrillation or atrial flutter (Class I) • Multifocal atrial tachycardia (Class IIb) • Inappropriate sinus tachycardia (Class IIb) • Control of blood pressure in hypertensive emergencies (labetalol)

  37. Beta-BlockersDosing (adult) Atenolol • 5 mg IV over 5 minutes followed by another 5 mg IV dose 10 minutes later. Monitor BP, heart rate, and ECG closely. • If patient tolerates full IV dose (10 mg), begin oral atenolol therapy 10 minutes after last IV dose

  38. Beta BlockersDosing (adults) Esmolol • 0.5 mg/kg over 1 minute, followed by a maintenance infusion at 50 mcg/kg/min for 4 minutes. If the response is inadequate, administer a 2nd bolus of 0.5 mg/kg over 1 minute and increase the maintenance infusion to 100 mcg/kg/min. • Preferred by many physicians in the management of narrow-QRS tachycardias because it is short-acting (half-life 9 minutes)

  39. Beta BlockersDosing (adults) Labetalol • 5 to 20 mg slowly IV push over 2 minutes. Additional doses of 10 to 40 mg may be administered until a desired supine BP is achieved or a total of 150 mg has been administered. • May be administered by IV infusion. Mix two 20 ml vials in 160 ml of IV solution. The resulting concentration contains 200 mg/200 ml IV solution (1 mg/ml). Administer at a rate of 2 ml/min to deliver 2 mg/min.

  40. Beta BlockersDosing (adults) Metoprolol • 5 mg slow IV push over 5 minutes x 3 as needed to a total dose of 15 mg over 15 minutes. Closely monitor BP, heart rate, and ECG • In patients who tolerate the full IV dose (15 mg), begin oral metoprolol therapy 15 minutes after last IV dose.

  41. Beta BlockersDosing (adults) Propranolol • 1 mg slow IV push. Repeat every 5 minutes to a maximum of 5 mg. Usual dose required is 2 to 4 mg. Do not push faster than 1 mg/min to diminish the possibility of lower BP and causing cardiac standstill. Monitor BP, heart rate, and ECG closely.

  42. Beta-BlockersPrecautions Atenolol • Use with caution in patients with impaired renal function

  43. Beta BlockersPrecautions Esmolol • In clinical trials 20 to 50% of patients experienced hypotension, SBP <90 mmHg and/or DBP < 50 mmHg. Monitor patients closely, especially if pretreatment BP low. Decrease of dose or termination of infusion reverses hypotension, usually within 30 minutes. • Infiltration and extravasation may result in skin sloughing and necrosis. • Administer with caution in patients with impaired renal function • Fatal cardiac arrests have occurred in patients receiving esmolol and verapamil

  44. Beta BlockersPrecautions Labetalol • Use with caution in patients with impaired hepatic function. • Symptomatic postural hypotension is likely to occur if patients are tilted or allowed to assume the upright position within 3 hours of receiving IV labetalol

  45. Beta BlockersPrecautions Metoprolol • Use with caution in patients with impaired hepatic functions

  46. Beta BlockersPrecautions Propranolol • Use with caution in patients with impaired hepatic or renal functions

  47. Beta BlockersContraindications • Heart rate < 60 beats/minute • AV block greater than first degree • Moderate to severe heart failure • Cardiogenic shock • Use with caution in conjunction with medications that slow conduction and in those that decrease myocardial contractility

  48. Beta BlockersSpecial Consideration • In general, patients with bronchospastic disease should not receive beta-blockers.

  49. CardiologyDiazepam • Generic Name: Diazepam • Trade Name: Valium • Classification: Anticonvulsant and sedative. Benzodiazepine. • How Supplied: Ampules and prefilled syringes containing 10 mg in 2 ml of solvent.

  50. DiazepamMechanism of Action • Suppresses the spread of seizure activity through the motor cortex of the brain. • It does not appear to abolish the abnormal discharge focus. • It induces amnesia

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