Exam Questions and Correct
Answers Graded A+
Sinus tachycardia causes - Answer ✔ common in normal healthy heart
-cardiac response to increase O2 demand, exercise
-response to: hypovolemia, hypoxia, hyperthyroidism, anemia, pain, fever, CHF, stress
sinus tachycardia significance - Answer ✔ -benign in healthy individuals
-increased O2 requirements may lead to: chest pain, extension of myocardial infarction,
pump failure
sinus tachycardia treatment - Answer ✔ only if symptomatic: low BP, pulmonary
congestion, shock, decreased consciousness, CHF, acute MI, SOB, chest pain
-treat the cause! fluids, O2, morphine, nitro, BB
Sinus arrest/pause - Answer ✔ -abrupt interruption of sinus rhythm
-arrest if packemaker activity of SA node-temporary electrical silence
-possible cause: MI involving atria/SA node
-watch for signs of decreased CO
sick sinus syndrome - Answer ✔ -alternating bradycardia and tachycardia
-usually seen in elderly (or diseased heart)
-may be drug induced, related to infectious process, collagen disease or pericardial
disease
-Treatment: pacemaker, meds
Atrial arrythmias - Answer ✔ originate in area of atria other than SA node
P wave is ectopic: morphology: shape looks different, focus is somewhere in atrial
tissue
-conduction to ventricles either via normal or abnormal pathways
Premature atrial contractions (PACs) - Answer ✔ interrupts regular rate of dominant
rhythm of heart
types:
1-classic of standard type
2- non-conducted
3- PAC with aberrant conduction
, PAC characteristics - Answer ✔ -irregular rhythm
-P waves: premature, morphology differs, usually noncompensatory pause
-PR: normal, prolonged or blocked
-QRS: normal, widened (aberrant)
PAC significance - Answer ✔ -rare or occasional, no effect
-frequent will decrease CO: decreased ventricular filling, premature excitation of
ventricles
-can lead to more significant atrial dysrhythmias
PAC causes - Answer ✔ -electrolyte disturbances
-meds
-stimulants (cigs, caffeine)
-alcohol
-stress, strong emotions
-hypoxia
-fatigue
-cardiovascular disease
electrical properties of the heart - Answer ✔ 1-automaticity
2-excitability
3-conductivity
4-contractility
automaticity - Answer ✔ =the ability of cardiac cells to depolarize spontaneously w/o
external stimuli
-cells able to modify membrane to pull in Na+ while K+ exits
-rapid depolarization when threshold potential is reached
-only certain cells have property of automaticity: SA node, AV node, bundle of HIS,
purkinje network
influence of the nervous system - Answer ✔ SYMPATHETIC: affects atria and
ventricles. increases HR and conduction
PARASYMPATHETIC: affects only the atria. decreases HR, conduction and irritability
excitability - Answer ✔ =capability of cardiac cells to depolarize in response to a
stimulus
-all cardiac cells have this property
conductivity - Answer ✔ =property of some cardiac cells that enables them to transmit
electrical impulses
-electrical cells of the heart are arranged in a system of pathways=CONDUCTION
SYSTEM