Cardiac Rhythm

“Until the day Jesus returns, I will live in a body which does not function as God originally intended. My brain, which is a key, central, integral part of my body, will not function correctly. Chemicals will become imbalanced. Serotonin will not be properly absorbed. Norepinephrine will be unevenly distributed. Synapses won’t fire correctly. My brain, just like every other part of my body, is prone to illness.”

Sinus Rhythm - 6 second strip qrs times 10 = heart rayr

Sinus Rhythm

Atrial Fibrillation A-Fib – no p wave

Atrial Flutter – fluttering of p waves

Supra Ventricular – heart is beating fast and the heart can’t fill and the heart can’t pump

First Degree Atrioventricular block 1° AV Block – p waves are far away from qrs

Third Degree Atrio Ventricular Block 3° AV Block – p waves completely dissociated from qrs complexes

Ventricular Tachycardia V-Tach – qrs complexes are wide, one ventricle must be stimulating the other

Ventricular Fibrillation V-Fib VF – no qrs complexes, common rhythm in cardiac arrest

Cardiac Muscle Cell The cardiac muscle cell can repeatedly contract or beat by itself

Cardiac Muscle Cell Na+ Ca2+ K+ Cl- The cardiac muscle cell requires these ions and their membrane channel

Charged and Ready The Na+/K+ pump creates: - sodium concentration gradient - more outside than inside - potassium concentration gradient - more inside than outside The Na/Ca pump creates - calcium concentration gradient

Action Potential Step 1 sodium channels open Sodium rushes in, causing a voltage change across the membrane

Action Potential Step 2 calcium channels open Calcium rushes in, causing muscle contraction Na channels are closing now

Action Potential Step 3 potassium channels open Potassium ‘resets’ the membrane by rushing out until the membrane is charged and ready for another action potential

Cardiac muscle cell Each separate cardiac muscle cell can repeatedly contract or beat by itself, at it’s own pace.

Fibrillation When the cells beat separately and on their own, this is called fibrillation

Fibrillation When the ventricles, the main pumps, are fibrillating there can be no heart beat

Synchrony It is important that the cells work together

Conduction Pathway Certain specialized heart muscles help conduct the signals and maintain synchrony

Conducting System of the Heart Picture

Atrio-Ventricular Node R-Atrium Picture

Sympathetic Neuron NE – norepinephrine Increased HR

Parasympathetic Neuron Ach Decreased HR

P wave – atrial excitation - think of it as lighting the fuse QRS wave – ventricular excitation - think of it as the BANG! T wave – ventricular repolarization - think of it as the RESET

What do we do in V-fib? Chest compressions is the first round of treatment for V-fib 100 beats/minute

Pulseless arrest BLS Algorithm: Call for help, give CPR Give oxygen when available Attach monitor/defibrillator when available Allow for full recoil using chest compressions

Oxygen is a drug - most important drug in pediatric arrhythmia Use Bag valve mask or ambu bag

Bag Valve

Ambu Bag

VF/VT – pulseless Give 1 shock Manual biphasic: device specific (typically 120 to 200J) AED: device specific – automatic external defibrillator Monophasic: 360J Resume CPR immediately

Stand clear Shock!

Fibrillation By applying a large electrical shock sometimes we can convert fibrillation into a perfusing rhythm – synchrony So must do chest compressions, oxygen, electricity

Defibrillation Applying a shock to the heart is called defibrillation V-fib – oxygen is one of the greatest anti-arrhythmic drugs

Resume CPR immediately after the shock When the IV is available, give vasopressin during the procedure (before or after the shock) Epinephrine 1mg IV Repeat every 3 to 5 mins or may give 1 dose of vasopressin 40IV to replace first or second dose of epinephrine

Epinephrine produces beneficial effects in patients during cardiac arrest primarily because of it’s α-adrenergic stimulating vasoconstrictive properties

Vasopressin – is a nonadrenergic vasoconstrictor Vasopressin is also called Anti-Diuretic Hormone (ADH) and is released by the posterior pituitary of the brain

Resume CPR immediately after the shock Consider antiarrhythimics, give during CPR (before or after the shock) - amiodarone - lidocaine

Lidocaine is a “Class 1” antiarrhythmic It is a sodium channel blocker in heart muscle slowing down heart contraction

Amiodarone Is a “Class 3” antiarrhythmic It is a: sodium channel blocker, potassium channel blocker, calcium channel blocker, α & β adrenergic blocker

V-Fib interventions Chest compressions Oxygen Shock!

V-Fib Drugs Epinephrine Vasopressin (ADH) Lidocaine Amiodarone

Do not confuse Ventricular fibrillation – cardiac arrest Atrial fibrillation – the ventricles are still beating – will have a pulse, irregularly irregular ECG, will have tachycardia – you may call this as atrial fibrillation with rapid response

A-fib Major cause of strokes Major reason to give coumadin Don’t want to convert A-fib to SR (sinus rhythm) until we know there is no thrombus

A-Fib Stable Unstable

Digoxin Lanoxin Digitalis glycoside Blocks Na/K ATPase increasing calcium availability Antiarrhythmic Positive Inotrope Negative Chronotrope Slows AV conduction

Digoxin Risks Arrythmia Toxicity with hypokalemia

Supra Ventricular Tachycardia ECG Picture

SVT A-Fib RVR – rapid ventricular rate - Control ventricular rate - Β-blockers (Class 2) - Calcium channel blokcers (Class 4) - verapamil - diltiazem

Adenosine Endogenous nucleotides which slows conduction through the AV node IV antidysrythmic used in PSVT – paroxysmal supra ventricular tachycardia

SVT Adenosine - safe - “reset” AV node - stops heart beat for about 6 secs - 6 very long seconds…… Will not reverse a-fib a-flut

Atrial flutter – treat the same as a-fib

First Degree AV Block ECG Picture

Third Degree AV Block ECG Picture – p waves completely dissociated from qrs complexes

Bradycardia Bradycardia means low heart rate Bradycardia is heart rate less than 60 Relative bradycardia means heart is beating too slow just to keep up with demand

Bradycadia Stable Unstable

Bradycardia Atropine - cholinergic blocker Epinephrine - adrenaline

Procaine – similar to Lidocaine Procainamide - sodium channel blocker - watch for hypertension - lupus-like adverse effects when taken chronically