Advanced MedSurg Exam 1

Dysrhythmias

What is a dysrhythmias?

Disorder of formation of electrical impulses of heart of conduction (hemodynamic instability)

What is the difference between the two types of cardiac cells?

Pacemaker cells: automatic, generate impulse

Muscle cells: contract/relax, no impulses generally, pump blood

How does the cell conduction system work?

Impulse from SA node—> left atrium—> left ventricle—> AV node—> purkinje fibers—> all cells

What is the role of an EKG?

Information ONLY about electrical events NOT contractile events (always check pt)

Why should you always check the patient even if EKG is normal?

pulseless electrical activity can occur

Why can tachycardia be detrimental?

Increase myocardial oxygen demand, decreases ventricular filling and coronary artery perfusion time

Why can bradycardia be detrimental?

Decrease in cardiac output can cause syncope and chest pain

How is cardiac output calculated?

HR x Stroke volume (amount of blood pumped out with every beat)

What is the process of impulse formation?

Polarized state (resting negative charge of myocardial cell)—> depolarized state (becomes positive)—> repolarization (cell is restored to resting state with ATP)

How is depolarization shown on an EKG?

atrial depolarization: P wave

Ventricular depolarization: ST segment and T wave

What is the PR interval on an EKG?

Amount of time for SAN stimulation, and atrial depolarization through AVN before ventricular depolarization) 0.12-0.20 seconds

What does the QRS complex represent (and normal range)?

0.06-0.10 seconds (ventricular depolarization)

What is the ST segment on an EKG indicate?

normal isoelectric, if above or below could be ischemia or infarction

What does the T wave represent?

Ventricular repolarization following QRS complex

What does the QT interval represent?

ventricular depolarization and repolarization

What can a prolonged QT interval indicate?

ventricular dysrhythmia

How is HR calculated on an EKG?

count number of QRS complexes in 6 second strip and multiply by 10

What is Normal Sinus Rhythm (NSR)?

Eletrical impulse starts in SA node and travels through normal conduction pathway

What is normal criteria for sinus rhythm on EKG?

1 P wave per QRS

What are the 6 kinds of SA node dysrhythmias?

(Sinus) tachy, brady, arrhythmia, pause, arrest, sick sinus syndrome

What is sinus tachy?

SAN creates an impulse at a faster than normal rate >100 bpm

What are causes/ tx for sinus tachy?

cause: shock, anemia, stress, hypovolemia, blood loss, infection, hypoxia etc.

tx: treat underlying cause, monitor

What dysrhythmia is this EKG showing?

Sinus tachy

What is sinus brady?

SAN creates impulse slower than normal rate <60 bpm

What dysrhythmia is this EKG showing?

sinus brady

What are causes and tx of sinus brady?

cause: decreased metabolic needs, intracranial pressure, MI, vagal stimulation, meds, hypothyroidism

tx: only if symptomatic, atropine for vagal cause, pacemaker

What are the types of atrial dysrhythmias?

Premature atrial contractions, afib, atrial flutter

What is premature atrial contraction (PAC)

An early electrical impulse discharges in atrium before next normal impulse of SAN

What is an ectopic beat?

pacemaker site outside of the SAN (like atrium)

What is the cause and tx for PAC?

Causes: HF, hypokalemia (<3.5) , atrial ischemia, meds (albuterol)

Tx: no tx needed generally, assess, remove causing agent (ex. caffeine)

What is atrial flutter?

Atria is depolarized at rates of 250-400 times per minute from re-entry circuit

What is this EKG showing?

atrial flutter

What are causes for atrial flutter?

underlying cardiac disease, HTN, CAD, hypoxia, HF, SAN damage

What can be caused by the lack of atrial contraction from atrial flutters?

blood stasis and thromboembolisms

What are the treatments for atrial flutters?

control HR (diltiazem, beta blockers), create NSR (amiodarone, cardioversion), Vagal maneuvers (carotid sinus massage, cough) anticoagulation 

What is afib?

Uncoordinated atrial electrical activation from many areas in atria

What is the ventricular rate dependent on?

the ability of AV node to conduct atrial impulses 

What are characteristics of Afib?

NO P WAVE, very irregular EKG

What is the clinical significance of Afib?

Loss of systolic volume, reduced cardiac output, risk for thromboembolism

What are the tx goals for afib?

decrease ventricular rate, convert to NSR, prevent thromboembolism

What meds can be used to treat afib? (meds for rate control / NSR conversion)

Rate control: CCBs, Beta blocker, dioxin

NSR conversion: amiodarone, dofetilide, flecanide

Where is the common origin of thromboembolisms caused by afib?

left atrial appendage closure

What is tx for afib caused thromboembolism?

Antiplatelets (aspirin), anticoags (warfarin), Factor Xa inhibitors (-ban)

If your pt is dizzy, unstable BP what is the tx?

cardioversion (synchronized defibrillation)

What is a premature ventricular contraction (PVC)?

Premature impulse that originates in the ventricle before normal sinus impulse

What are characteristics of PVC?

QRS is wide, ST and T wave changes, irregular rhythm

What are the causes of PVC?

hypoxia, acidosis, electrolyte imbalances (hypokalemia), OSA

What is the tx for PVC?

remove causing agent, lidocaine

What is this EKG showing?

premature ventricular contraction (PVC)

What is ventricular tachycardia (VT)?

3 or more PVCs in a row, rate >100, EMERGENCY, can be life threatening

What are characteristics of VT?

high rate, regular rhythm, QRS wide and no P waves

What are causes of VT?

MI, ischemia, hypoxia, electrolyte imbalance, CAD, acidosis, HF, valve disease 

What are the treatments for VT? (stable, unstable, pulseless

Stable: antiarrhythmic drugs (amiodarone)

unstable: sedate, cardioversion, drugs

Pulseless: defibrillation/ CPR

What does this EKG show?

ventricular tachycardia (VT)