Arrhythmias Quiz Part (1)

Acute treatment of the symptomatic and/or hemodynamically unstable patient with sinus bradycardia includes administration of :

• Bat

• Hat

• Cat

• 0.5 mg of IV Atropine

The pacemaker of the heart is not the SA node

• True

• False

The SA node has the greatest degree of automaticity

• True

• False

Abnormal initiation of electrical impulses occurs as a result of abnormal automaticity

• True

• False

During phase 2, potassium ions continue to exit the cell, but the membrane potential is balanced by an influx of calcium and sodium ions, transported through slow calcium and slow sodium channels, resulting in a plateau.

• True

• False

CARDIAC ARRHYTHMIAS Cardiac arrhythmias are classified into two broad categories: supraventricular (those occurring above the ventricles) and ventricular (those occurring in the ventricles).

• True

• False

During phase 3, the efflux of potassium ions greatly exceeds calcium and sodium influx, resulting in the major component of ventricular repolarization.

• True

• False

The mechanism of abnormal impulse conduction is traditionally referred to as :

• Dog

• Cat

• Monkey

• Reentry

These three conditions are  (1) at least two pathways for the impulse to travel  (2) a “unidirectional block” in one of the conduction pathways                                                                                     (3) slowing of the velocity of impulse conduction down the other conduction pathway.

• True

• False

Myocardial ischemia does not alter impulse conduction velocity

• True

• False

In patients with hemodynamically unstable sinus bradycardia unresponsive to atropine, transcutaneous pacing may be initiated.

• True

• False

Ventricular myocyte resting membrane potential is usually –70 to –90 mV

• True

• False

Abnormal atrial automaticity will not result premature atrial contractions, atrial tachycardia or atrial fibrillation

• True

• False

Class IV drugs are the calcium channel blockers (CCBs), diltiazem and verapamil

• True

• False

He class I drugs are subdivided into classes IA, IB, and IC

• True

• False

Cardiac arrhythmias are caused by

• Abnormal impulse initiation

• Abnormal impulse conduction

• Both answers are correct

• All of the above answers are wrong

If the patient is taking any medication(s) that may cause symptomatic sinus bradycardia, they should be discontinued whenever possible. If the patient remains in sinus bradycardia after drug discontinuation and after five half-lives of the drug(s) have elapsed, then the drugs(s) can usually be excluded as the etiology of the arrhythmia

• True

• False

The class IC drugs have the greatest potency for slowing ventricular conduction

• True

• False

A premature impulse may be conducted down both pathways if it is only slightly premature and arrives after the tissue is no longer refractory

• True

• False

When the membrane potential reaches this threshold, the fast sodium channels open, allowing sodium ions to enter the cell rapidly

• True

• False

In patients with hemodynamically unstable or severely symptomatic sinus bradycardia unresponsive to atropine and in whom temporary or transvenous pacing is not available you can use :

• Isoproterenol

• Dopamine

• Epinephrine 

• All of the above

Class III drugs are those that inhibit ventricular repolarization and prolong refractoriness

• True

• False

Atropine should not be used cautiously in patients with myocardial ischemia or MI

• True

• False

Class IA drugs have intermediate potency, and class IB drugs have the lowest potency

• True

• False

Which one do you like?

• Option 1

• Option 2

• Option 3

• Option 4

This rapid influx of positive ions creates a vertical upstroke of the action potential. This previous is considered as phase 0, which represents ventricular depolarization. At this point, the fast sodium channels become inactivated.

• True

• False

Class II drugs are (Alpha) blockers 

• True

• False

Phase 1 repolarization occurs primarily as a result of an influx of potassium ions.

• True

• False

Amiodarone is a drug that is classified as :

• Class IA

• Class IC

• Class IV

• Class III

Class (I) drugs primarily increase ventricular automaticity and speed up conduction velocity.

• True

• False

Lidocaine & Mexiletin are classified into calss

• Class II

• Class II

• Class IB

• Class IA

Sinus bradycardia, originating in the SA node, is defined by a sinus rate less than 50 beats/min

• True

• False

Ventricular depolarization begins, consisting of phases 1 through 3 of the action potential.

• True

• False

During phase 4, Calcium ions gradually enter the cell, increasing the threshold again to –60 to –80 mV and initiating another action potential.

• True

• False

During each action potential cycle, the potential of the membrane rapidly increases to a threshold potential due to a rapid influx of sodium into the cell

• True

• False

When circulated blood returns to the heart via venous circulation, blood enters the right atrium. Right atrial contraction and changes in right ventricular pressure result in delivery of blood to the right ventricle through the tricuspid valve. Right ventricular contraction pumps blood through the pulmonic valve through the pulmonary arteries to the lungs, where blood becomes oxygenated. The blood then flows through the pulmonary veins into the left atrium. Left atrial contraction and changes in left ventricle (LV) pressure result in delivery of blood through the mitral valve into the LV. Contraction of the LV results in pumping of blood through the aortic valve and to the tissues of the body. Mechanical activity of the heart (contraction of the atria and ventricles) occurs as a result of the electrical activity of the heart.

Reentry is often initiated as a result of an abnormal premature electrical impulse (abnormal automaticity); therefore, in these situations, the mechanism of the arrhythmia is both abnormal impulse formation (automaticity) and abnormal impulse conduction (reentry).

The prevalence of sick sinus syndrome is approximately 1 in 600 individuals older than 65 years

In patients with sinus bradycardia due to underlying correctable disorders (such as electrolyte abnormalities or hypothyroidism), management consists of correcting those disorders

Nonpharmacologic Therapy : Long-term management of patients with sick sinus syndrome requires implantation of a permanent pacemaker

 Remember to 1- Monitor the patient’s heart rate and alleviation of symptoms. 2- Monitor for adverse effects of medications such as atropine (dry mouth, mydriasis, urinary retention, and tachycardia).