Cardiac Dysrhythmia And Tachycardia Flashcards
Normal sinus rhythm on an EKG
Lead II (heart rate and rhythm, specially P wave). Conduction starts with SA node->AV node (conduction slows down because the AV node cells are small and use calcium channels instead of sodium channels(found around ventricles) the time it takes from calcium channels to sodium channels gives time for atrial contraction and relaxation and ventricles can fill)-> HIS bundles(conduction goes fast, uses sodium channel, divides into left and right bundle branches(Purkinje Fibers) -> Purkinje fibers (conduct ventricular cells, ventricular depolarization occurs) T waves, and QRS complex are in same direction because(positive), because EKG gives information on difference of change(change in balance of potential) and epicardial cells repolarize first then endocardial cells.
Supraventricular Tachycardia (SVT)
Abnormally high heart rate(>100) , symptoms: palpation(pounding), chest pain, shortness of breath, anxiety, dizziness. Diagnosis: symptoms, EKG, holter monitor. Risk factors: inherited condition, structural abnormalities, CAD, COPD, pulmonary embolism, hyperthyroidism, alcoholism.
Atrial fibrillation(AFibb)
One of supraventricular tachycardia, disorganized signals from SA node leading to irregular atrial conduction or even AV nodes irregular conduction. EKG will have uneven RR intervals and no P wave present because of atrial spasm. Risk factors: diseased atrial tissue, inflammation of atrial tissue, atrial enlargement (high blood pressure, valve disease, lung disease.), hormonal abnormalities, high risk of stroke.(blood being stagnant in atrium can lead to blood clot formation.-> stroke risk).
Atrial flutter
One of the supraventricular tachycardia. When SA node fails, automaticity foci fires (back up at the rate of 60 to 80 bpm), atrial flutter is an irritable automaticity focus firing at a rate of 250 to 300 bpm. This leads to atrial contraction at the rate of 250 to 300 bpm this firing also hits AV node but still AV node only fires at a rate of 150 bpm due to it having a refractory period (a period when AV node won’t fire despite of receiving a signal). EKG: shows multiple P waves with even RR intervals saw tooth pattern is shown.
Multifocal atrial tachycardia
A type of supraventricular tachycardia, mainly occurs in older people with lung disease. Multiple automaticity foci fires in unorganized pattern and this leads to unorganized pattern firing from Av node. EKG: heart rate is >100 or more than or equal to 3 different P wave morphology, PR interval length varies, narrow QRS complex( <0.12 sec / 3 boxes). Risk factors: atrial distention.(COPD, CAD, heart failure), increase intracellular, calcium leading to untimely depolarization (hypokalemia, hypo magnesemia, hypoxia, COPD, acidemia, sepsis).
Atrial ventricular reentrant tachycardia
It’s a type of supraventricular tachycardia. Accessory pathway( extra pathway through which excitation can occur between atria and ventricle). When there is conduction of both AV node and accessory pathway, it causes AVRT. Wolff-Parkinsons syndrome (when conduction from SA node goes to both AV node and accessory pathway, leads to short PR interval (less than or equal to 0.12 sec on EKG).
Atrioventricular Nodal Re-entrant Tachycardia
There is two pathways, running down the AV node(slower pathway(impulse travels slowly through AV node, shorter refractory period) and faster pathway(impulse travels down faster, but has a longer refractory period). When a premature beat comes in, which ever path has recovered from refractory period in AV node will get activated, which leads to much faster signals down to ventricle. EKG: narrow QRS complex (less than or equal to 0.12 sec , HR more than or equal to 100 bpm -> 150-300.
Ventricular tachycardia
Rapid heart rate from ventricular cells, compromises blood circulation due to low filling in chambers. Causes: ventricular cell irritation (hormones, low oxygen supply, stretching), leads to scar tissue in ventricles, causing VTACH. Symptoms: shortness of breath, chest pain, palpitations, lightheaded/dizziness, fainting/passing out, ventricular fibrillation. EKG: only QRS complex are shown. Risk factor: CAD, electrolyte, abnormalities, heart attack, hypertrophic cardiomyopathy, dilated cardiomyopathy.
Torsades de pointes
A type of ventricular tachycardia, polymorphic(multiple QRS intervals and long QT). EKG: shows high and low QRS alternatively and long QT ( more than or equal to 0.45 sec (male) and more than or equal to 0.47 sec (female)). Heart rate: 250 to 300. Long QT can come from congenital( genetic mutation), acquired(anti-arrhythmia meds).
Ventricular fibrillation
Ventricular muscle spasm and don’t pump blood out to the body due to uncoordinated signals and ventricles. No pulse is felt, chest pain, pale/blue skin. EKG: squiggling lines. Causes: irritable, ventricular cells( CAD, scar tissue, electrolyte abnormalities, cardiomyopathy, heart attack, electrocution(can disrupt normal heart signaling).
Pulseless electrical activity and asystole
Ventricular asystole (no electrical activity-> no ventricular contractions-> no cardiac output-> flatline on EKG). Pulseless electrical activity(electro mechanical uncoupling (despite of electrical activity there is no contraction), cardiac tamponade (due to pressure surrounding heart leads to no heart contraction, even when there is electrical activity present in the heart).
Defibrillation is only attempted for shockable rhythms (ventricular fibrillation, pulse less ventricular tachycardia) for non-shockable rhythms, shocking is not advised, to treat these CPR, vasoconstrictive medications, consider reversible factors( Hs and Ts -> hypothermia, hypoxia, increase in hydrogen ions(acidosis), hypo/hyperkalemia, hypoglycemia, hypothermia( <95 or 35C), toxins, tamponade, tension pneumothorax (air creates pressure and crushes lungs ), thrombosis/pulmonary embolism).
Electrocardio version
Electro shock therapy(atrial fibrillation, and ventricular tachycardia, uses defibrillator). Defibrillation (synchronized electrical cardioversion(used to treat afib, atrial flutter, atrial ventricular nodal reentrant tachycardia, VTACH, (if the pulse is stable medication is used, if the pulse is unstable then synchronized cardioversion setting is used).
Defibrillation (used to treat a VTACH with no pulse, also called asynchronous cardioversion. Ventricular fibrillation, higher energy levels is used in this setting). Electrical shock therapy depolarizes all the heart cells to reset electrical activity).
Pacemaker
Used to make heart maintain normal heart rate in cases such as bradycardia, tachycardia, coordinate contractions between ventricles. Two parts(Pulse generator and control center). Four types(external-> transcutaneous, used in emergency, temporary epicardial-> placed during heart surgery due to inflammation that occurs and can cause bradycardia, temporary endocardial pacemaker/transvenous pacemaker-> used for temporary heart rate abnormality(drug induced bradycardia, AV nodal irritation, trauma), permanent pacemaker-> used for third-degree, heart block, second-degree heart block, sinus Bradycardia ).
Anti-arrhythmias
Class I (sodium channel blockers-> delays phase 0(depolarization) and that extends refractory period adding times in cardiac conduction, used to treat supraventricular tachycardia (Atrial fibrillation(AFibb), Wolfe Parkinson white )
Class II (beta blockers-> block beta receptors on SA and AV node to reduce sympathetic stimulation-> slows down depolarization-> SA node firing goes down -> AV node conduction goes down, used on AFib, VTACH).
Class III ( potassium channel blockers-> blocks potassium channels-> increases refractory period-> spacing out depolarization-> slowing down heart rate-> contradictory for pre-existing elongated QT on EKG)
Class IV ( calcium channel blockers-> blocks calcium channels, two types:Dihydropyridine (DPH -> blood vessels ), Non - Dihydropyridine (Non - DHP -> SA and AV node -> longer phase 0 (depolarization) -> firing decreases-> AV node conduction goes down, used for SVT).
Cardiac ablation
Used to treat arrhythmias, diseased heart tissue is damaged, treat: afib, atrial flutter, VTACH, tachycardia from accessory muscles, atrial ventricular reentrant tachycardia . This is used when electrical shock therapy doesn’t work.
