module 5 quiz questions Flashcards
What is a disrhythmia / arrhythmia?
A change in the normal rhythm of the heart beat
Range from occasional “missed”, more rapid or slower beats, to serious disturbances that impair the pumping ability of the heart
What are the two general causes for disrhythmias?
Abnormal rate of impulse generation from the SA node or other pacemaker
Abnormal conduction of impulses through the heart’s conduction system
Define sinus rhythm
Normal heartbeat
define brachycardia,
Slow heartbeat
define tachycardia
Fast heartbeat
define sinus arrhythmia.
Irregular heartbeat (during respiration)
Describe atrial fibrillation.
Completely disorganized and irregular atrial rhythm accompanied by completely irregular ventricular rhythm. Causes pooling of blood in atria
Why can atrial fibrillation be sometimes asymptomatic?
Ventricular filling is not totally dependent on atrial contraction, so these arrhythmias may be asymptomatic
What is the greatest danger of atrial fibrillation
blood clots which will lead to stroke
Describe atrioventricular node abnormalities (heart block)
Occurs when conduction is excessively delayed or stopped at the AV node or bundle of His
Partial heart block (slower conduction – leads to first, second degree) to total heart block (no transmission – leads to third degree, where ventricles contract on their own, but cardiac output is greatly reduced)
Not all atrial beats getting through to the ventricles
Describe ventricular fibrillation
Ventricles quiver but do not contract – ineffective in ejecting blood (no cardiac output, so death within minutes if not corrected)
Disorganized electrical signals: ventricles quiver instead of contract. Patient unconscious as blood is not pumped to the brain. Immediate defibrillation is indicated. May occur in MI
describe asystole
No electrical activity in the heart / absence of a heartbeat (“flatline”)
Describe the purpose of cardiopulmonary resuscitation (CPR)
Purpose is to “massage” the heart with sufficient force to circulate sufficient blood throughout the body and throughout the heart muscle to maintain life. Performed when heart has stopped beating (asystole). (it is possible (but unlikely) that, with the heart muscle receiving sufficient oxygen, it may begin to beat spontaneously)
Describe the purpose defibrillation
Purpose is to interrupt the irregular electrical signals that are causing the ventricles to vibrate and not produce sufficient cardiac output. Once these signals have been stopped, it is possible for the heart to begin beating in a rhythmic fashion. Performed when the ventricles are fibrillating
Define diastolic heart failure.
A decrease in cardiac output caused by decreased filling of the left ventricle during diastole caused by reduced chamber size (left side only)
Identify (and understand the example for each) three causes for diastolic heart failure.
Decrease expansion of the ventricle (pericardial effusion)
Increase wall thickness and reduce chamber size (hypertrophic cardiomyopathy)
Delay diastolic relaxation (myocardial ischemia) (decreased energy for calcium pumps)
Remember that calcium must be removed from cytosol in order for myosin to detach from actin, allowing relaxation to occur
Describe the condition of cardiogenic shock and its effect on the heart
Enough blood volume, but decreased cardiac output due to decreased contractility, increased preload and increased afterload
Decrease in blood pressure causes responses (increase in epinephrine, RAAS) that increase oxygen/nutrient demand of the heart which puts further strain on the heart, resulting in it becoming incapable of pumping an adequate volume
Describe the condition of hypovolemic shock and its causes (3).
Not enough blood volume, caused by loss of whole blood (hemorrhage), plasma (burns) or interstitial fluid (diarrhea or diuresis) in large amounts
Describe the condition of distributive shock.
Result of massive vasodilation such that, although the volume of the blood has not changed, the amount of space containing the blood has increased, resulting in a decrease in BP below the required to drive nutrients across capillary membranes to the cells
Describe the condition of neurogenic shock. Be familiar with the causes.
Result of massive vasodilation resulting from overstimulation of the parasympathetic NS and under stimulation of the sympathetic NS
Trauma to the spinal cord or medulla, anaesthetic agents, severe pain
Describe the condition of anaphylactic shock, its cause and its treatment.
Release of histamine and other compounds by mast cells as a result of a type I hypersensitivity results in vasodilation and vascular permeability to the point of peripheral pooling and tissue edema
Results from widespread hypersensitivity reaction, known as anaphylaxis
Smooth muscle constriction can result in laryngospasm, bronchospasm and diarrhea
Treatment involves intramuscular administration of epinephrine to cause vasoconstriction and reverse airway constriction
Define the condition of septic shock.
Severe infection with a microorganism has 2 possible effects: the microorganism releases toxins that stimulate an overwhelming inflammatory response, and/or there is an overwhelming inflammatory response to the microorganism itself
Common type of vasodilatory shock
What manifestation differs between vasodilatory (distributive) shock and other categories of shock?
Manifestation differs from types of non-vasodilatory shock in that the skin is warm and flushed (non-vasodilatory types of shock constrict blood vessels, thus decreasing blood flow to skin (skin becomes cool and pale) while distributive types of shock produce dilation of blood vessels)
.Describe the condition of obstructive shock, and its most common cause.
Results from mechanical obstruction of the flow of blood through the central circulation
Most common cause is pulmonary embolism (other causes include cardiac tamponade, pneumothorax)
Elevated right heart pressure occurs
Significant decrease in cardiac output
