Cardiovascular Emergencies Flashcards
Which part of the heart is the strongest and largest of the four chambers? Why?
Left ventricle because it is responsible for pumping blood throughout the body.
Which vena cava vein is the largest?
Inferior
What is the intrinsic rate of the SA node, AV node, conduction below the AV node?
SA : 60 to 100
AV : 40 to 60
Below AV : 20 to 40
Describe electrical pathway of a contraction in the heart.
Impulses start in SA node, travel through R and L atria, resulting in atrial contraction.
Impluse travels to the AV where it transitions slowly down to the bundle of His.
Proceeds rapidly to the R and L bundle branches stimulating the interventricular septum.
Then the impulse spreads through the rest of the conduction system resulting in ventricular contraction.
Define excitability.
Ability of cells to respond to electrical impulses.
Define conductivity.
Ability of cells to conduct electrical impulse.
Define automaticity.
Allows cardiac muscle cells to contract spontaneously w/o stimulus from a nerve source.
What happens if the SA node does not fire an impulse?
Other myocardial cells with create their own impulses to stimulate the heart at a slower rate.
What controls the chronotropic, dromotropic, and inotropic states of the heart?
Autonomic nervous system, hormones, and heart tissues.
Describe the chronotropic, dromotropic, and inotropic states of the heart?
Chronotropic state controls the rate of the contraction.
Dromotropic state controls electrical conduction.
Inotropic state controls the strength of contraction.
Where does the electrical stimulus of heart contraction originate from?
Autonomic nervous system
Systole
Contraction of the ventricles and pumping of blood into the systemic circulation.
Diastole
Relaxation of heart.
Preload
Amount of blood returned to the heart to be pumped out. Directly affects afterload.
Afterload
Pressure in the aorta or the peripheral vascular resistance, against which the left ventricle must pump blood.
Stroke volume (SV)
Amount of blood ejected per contraction.
Cardiac output (CO)
Amount of blood pumped through the circulatory system in 1 minute.
CO = SV x HR
Starling law
The more cardiac muscle is stretched, the greater the force of its contraction, the more completely it will empty, and, therefore, the greater the SV.
What are the major controllable factors for AMI?
Cigarette smoking HTN Hyperlipidemia DM Lack of exercise Obesity
What are the major factors that cannot be controlled for AMI?
Older age Fmhx atherosclerotic CAD Race Ethnicity Male
Stable angina.
Occurs at a fixed frequency and is relieved by rest and/or medication.
Unstable angina.
Occurs w/o fix frequency and may or may not be relived w/ rest and/or medications.
Progressive angina
Stable or unstable angina that accelerates in frequency and duration.