defrilation and cardioversion

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Defibrillation and Cardioversion:

Defibrillation and Cardioversion cardiology dept

AIMS of learning:

AIMS of learning Definition Indications Contraindications Procedure Technique complications


Defibrillation Mechanism Current depolarizes myocardium Induces asystole temporarily Allows one pacemaker to regain control Random delivery of shock during cardiac cycle.


Defibrillation Factors to consider Duration of VF The longer VF lasts, the harder it is to cure The quicker the better Shock early-Shock often VENTRICULAR TACHYCARDIA with hemodynamic imbalance

CONTRAINDICATION of defibrillation:

CONTRAINDICATION of defibrillation Prior expression of patients who wish not to be resuscitated


Defibrillation Factors to consider Myocardial environment/condition Hypoxia, acidosis, hypothermia, electrolyte imbalance, drug toxicity impede conversion Do NOT delay shock trying to correct problems


Defibrillation Factors to consider Heart size/body weight Pedi requirement lower than adult 2 J/kg initial shock 4 J/kg repeat shocks Direct size/energy relationship in adults unknown 200 to 360 J


Defibrillation Previous countershock Repeated shocks lower resistance Give three initial shocks in 30-45 sec One quickly after another with little time between


Defibrillation Factors to consider Paddle size Adults (large paddles) 10-13 cm diameter Pediatric (small paddles usually < 1 yr) Children 8 cm Infants 4.5 cm


Defibrillation Use largest size that completely contacts chest without paddles touching Small paddles: concentrate current, burn heart Large paddles: reduce current density


Defibrillation Paddle placement One to right of sternum below clavicle; Other to left of left nipple in anterior axillary line Reversing paddles marked “apex--sternum” does NOT affect defibrillation AP placement can be used to defib small children with adult paddles


Defibrillation Paddle-skin interface Cream, paste, saline pads, gelled pads Decreases resistance to current flow Avoid smearing or running: “bridges” charge NEVER use alcohol!!!


Defibrillation Paddle contact pressure Firm pressure of 25 pounds Deflates lungs; Shortens current path Do not lean on paddles; They slip


Cardioversion Definitions Cardioversion Delivery of energy synchronized to QRS complex Used in Non-Arrest patients only Only VF/VT ( pulseless ) can be defibrillated


Cardioversion Definitions Synchronized cardioversion Timing of shock to avoid peak of T-wave Prevents VF caused by delivering shock during vulnerable period


Cardioversion Indications Tachyarrhythmias which: Cause or worsen hemodynamic compromise Cause or worsen ischemic heart disease Are resistant to drug therapy


INDICATIONS OF CARDIOVERSION 1)ATRIALFIBRILATION/ATRIAL FLUTTER A)Pt with atrial fibrillation/flutter >48hrs(or unkown )or anticoagulation for >3-4wks(INR 2-3) b)acute onset atrial fibrilation with associated hemodynamic compromise e.g angina,MI,PE,hypotension,heart failure

INDICATIONS OF cardioversion:

INDICATIONS OF cardioversion c) atrial fibrilation /flutter of of unkown duration and absence of thrombus in lft atrium or lft atrial appendage on transesophageal echocardiogram D) atrial fibrilation /flutter <48hrs n anticoagulation option depnd upon risk

INDICATIONS of cardioversion:

INDICATIONS of cardioversion 2) atrial tachycardia 3) atrioventricular nodal reentrant tachycardias 4) reentrant tachycardia associated with WPW syndrome 5) VT

CONTRAINDICATIONS of cardioversion:

CONTRAINDICATIONS of cardioversion 1) known atrial thrombus and no emergent indication 2) sinus rhythm/tachycardia 3) tachycardia associated with increased automicity a)multifocal atrial tachycardia b) junctional tachycardia 4) digitalis toxicity


CONTRAINDICATIONS OF cardioversion 5) severe electrolyte imbalance and nonemergent indication 6) unknown duration of atrial fibrilation /flutter in a nonanticoagulation patient in absence of transesophageal echo 7) pt who cannot b safely sedated


Cardioversion Procedure a) Patient preparation 1)informed consent 2)in elective cases fast for 6-8hrs 3)review pt history and examination 4)ensure airway,iv line 5)review pt medication and anticoagulation status(in A.FB) Patient must be on leads to cardiovert Sedate with Valium or Versed Do NOT make patient unresponsive


Cardioversion Procedure Activate synchronizer Observe marking of complexes to cnfirm the presentng rhythm May need to unsynchronize if: Random synching occurs Double-synching occurs


Cardioversion Procedure Charge to desired energy setting Depress buttons; Hold until discharge occurs If VF occurs, unsynchronize before defibrillating

Complications of cardioversion:

Complications of cardioversion 1) embolism 2) arrythmias 3) injuries lyke chest wall burns,injury to operator 4) airway compromise due to excessive sedation 5) MYOCARDIAL DEPRESSION,st seg elevation,elevated trop.I,CK -MB


TROUBLESHOOTING 1)Monitor doesn’t work 2)Timing artifact fals on t wave,(monitoring lead should b changed ) 3)Capacitor doesn’t charge 4) Cardioversion unsuccesful


SPECIAL SITUATIONS 1)PREXISTNG PERMANENT PACEMAKER or ICD electric current cnduct to implanted electrode n cause myocardial injury,kp the electrode away from device,interogate electrode befor n aftr cardioversion 2) PREGNANCY ,succesful without any harm to mothr or fetus



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