disturbance of heart electrical activity

--> dec. CO & BP

Electrolyte disturbances ** must be corrected before starting rx/rx therapy to prevent new arrhythmias

WATCH ELECTROLYTES K, Mag, Ca

atrial flutter

atrial fib **most common

ventricular tachy

ventricular fib

AICD's - defib & pace rhythms

catheter ablation therapy - burns slow cond path--> faster path continues

drug therapy: modify rhythms

*ALL ANTI-ARRHYTHMIC DRUGS ARE PRO-ARRHYTHMIC DRUGS

can cause new bad rhythm (^PVC's, prolonged QT, V fib) esp in pts w/ structural heart disease

antiarrhythmic rx classifications

class 1 - block Na channels: dec myocard excit and conduc velocity (lower HR), lower contractility (lower CO) *increase mortality

Quinidine - ProCAINamide - LidoCAINe - FleCAINide - Disopyramide, EnCAINide, Mexiletine (turns to lidocaine)+

WATCH FOR: slow HR, low BP, many drug interr, N/V (take w/ food), cinchonism w/ quinide (ringing ears, dizziness, void disturbances), liver tox, Ø HeartFailure

class 2- block adrenergic receptors (beta blockers)

class 3 - prolong repolarization (lengthen AP) AMIODARONE - Sotalol - Ibutilide - Dofetilide - Bretylium (no longer made)

class 4 - block Ca channels (verapimil, diltiazem)

*some rx's have actions of multiple classes

*some rx's don't fit any of these classes (digoxin, adenosine)

Quinidine (Quinaglute)

antiarrhyth

class 1 - treats atrial arhyth (not used much now)

PO 2-3x/day (SHORT acting)

• dec myocardial excitability, conduction velocity & contractility --> dec HR, BP, CO
•  anticholinergic properties (invol sm musc movement: GI, U tract, lungs)

contra: heart block, CHF, hypoTN, renal/hepatic dis

adverse: GI (N/V/D, anorexia, hypoTN, cinchonism (ringing ears), photosensitivity, rash, QT prolong, liver tox

*many drug interact

**black box warning - inc mortality

~Quinidine

antiarrhyth

similar: *all black box warnings - inc mortality

Procainamide (Procan)

Disopyramide (Norpace)

different:

lidocaine (IV) - Ø inc mortality, fx on contractility or BP drop

can cause arhythmias

Amiodarone (Cordarone, Pacerone)

antiarrhyt

works by blocking fast sodium channels, decreases peripheral resistance, slight increase in cardiac output, depresses sypathetic tone

PO/IV - Very long half life 2-3 mos(60-100 days)

Tx: life threatening Vfib/ Vtach

tx and prev Afib (most effective in CHF pt)

highly lipid sol & prot bound (goes everywhere)

met in liver (CYP 3A4-->active metabolite), exc in bile (no renal)

long half life  5 day loading dose then maintenance dose daily ~1yr steady state

Amiodarone action

antiarrhyth

Class 1, @ & ß blockers, ~thy hormones (iodine), antiinflam

Dec HR, no ∆ in BP, CO

contra: brady, heart block, cardiogenic shock, iodine allergy, severe thy dz (hyper or hypo)

interrac: many, esp digoxin, warfarin

*O loading doze in hosp (card monitor), IV in ICU

- correct low K & Mag prior (prevent arrhyth

long half life - to see effects, resolve adv rxn

Amiodarone can cause: (MEMORIZE)

antiarrhyth

pulm tox: need baseline & repeat CXR & PFT's

antiarrhythmic exacerbation - EKG & QTc measured

Liver dz - baseline & freq LFT's

Thyr tox - baseline & repeate TFT's

Optic neuropathy - eye exams for visual ∆

GI complaints (N**), photosensitivity (use sunscreen), skin color ∆ (blue-grey), hypoTN (with IV only, rate too high)

similar to Amiodarone

antiarrhythm

Sotalol (Betapace)

hosp use only:

-tilide (ibulitide- Corvert, dofetilide - Tikosyn)

Dronedarone (Multaq)

Verapamil

antiarrhyth

Ca chan blocker - slows SA/AV nodes

periph vasodil - dec myocard O2 demand & CO

control Afib/flutter, tx angina/HTN

contra: heart block, hypoTN, cardiogenic shock, CHF

high first pass (dont use w/ liver fail) renal elim

adverse: ***Constipation (blocked Ca - water cant get in), periph edema, dizziness, N, arhyth

interact: other arrhyth

Similar: Dilitazem (Cardizem) - better tolerated

Potassium-removing resins

Sodium polystyrene sulfonate (Kayexalate)

-O/rect: exchanges excess K for Na - prevent hyperkalemia arrhyth

caution: CHF, HTN, edema (inc Na levels)

*not systemic - intestine/colon only (2-12 hrs to work)

adv: hypokalemia, N/V/D, const/fecal impact

*dont give w/ other meds - binds them, prev absorp

Heparin

anticoag

IV/SubQ

inactivates factor X - prevents prothrombin-thrombin conversion ; dec fibrin

limits clot forming (*does not break up clots)

short 1/2 life - q 6hr

monitor by aPPT - large dose only (baseline - anticoag dose 1.5-2x baseline)

caution - bleeding, thrombocytopenia (tcp)

adverse - bleeding, hep induced tcp, HIT (allergic - stop), rash, osteoporosis (long term)

OD tx: protamine sulfate (only if bleeding)

Similar: Enoxaparin (Lovenox), Dalteparin (Fragmin) - no aPTT monitoring, Ø renal failure, 1-2/day

Direct Thrombin Inhibitors

argatroban

bivalirudin

lepirudin

anticoag

bind to thrombin - inhibit free & clot bound thrombin

treat HIT (hep ind tcp)

alt to hep in MI, CBA & procedures

can cause severe bleeding - monitor w/ aPPT

no reversal

Warfarin (Coumadin)

anticoag

O - tx & prophylaxis of clots - does not dissolve existing

in pts w/ DVT, PE, Afib, CHF (high clot risk, poor CO), mech heart valves, hypercoag states

PO 1/day

monitor - PT/INR 1/day *w/ heparin until ther range

blocks vit K (avoid Vit K foods - blocks efx of warfarin)

3-5 days for effect, 5-7 to wear off (hold 1 wk prior sg)

adverse: bleeding, bruising, rare tissue necrosis

Preg X

Rx inter risk (high prot binding, liver met) esp antibiotics, antiarrhythmics

reversal: Vitamin K (will bruise)

*fall risk

Clopidogrel (Plavix)

antiplatelet

∆ adenosine met - prevents platelet agg

reduce MI, CVA, vasc death, occlusion of stents or CABG (bypass graft) usually combo w/ aspirin

PO 1/day, 3-7 day steady state

met liver, high prot bind