Cardiovascular and Perfusion Flashcards
Define afterload.
The resistance to the ejection of the blood from the left ventricle.
Define cardiac output.
The amount of blood ejected from the left ventricle each minute.
When are instances that cardiac output would increase and decrease?
Increase: exercise, pregnancy, fever.
Decrease: sleep.
Define ejection fraction.
Percentage of blood leaving the heart each time it squeezes.
What is an infarction?
Necrosis of a portion of the heart muscle caused by obstruction in a coronary artery.
Define preload.
Volume of blood in the ventricles at the end of diastole, immediately before ventricular contraction.
What is pulse pressure?
Difference between the systolic and diastolic pressures.
Define pulsus alternans.
An arterial pulse with alternating strong and weak beats.
When can pulsus alternans be found?
In the setting of severe ventricular dysfunction.
What is stroke volume?
Amount of blood ejected by the ventricles with each contraction.
What is a venous thrombo-embolism?
Blood clots in the veins. It is an obstruction of a blood vessel by a blood clot that has become dislodged from somewhere else.
Systole vs. diastole.
Systole: Maximum pressure when ejection occurs.
Diastole: Relaxation, this is the minimal pressure exerted against the arterial walls at all times.
What are some examples of things that would increase cardiac output?
HR increase, greater heart muscle contractility, increased blood volume.
Peripheral resistance is directly correlated with what?
Blood pressure.
What is the normal circulating blood volume?
5000 mL.
What determines blood viscosity?
Hematocrit (% RBC).
As hematocrit increases how does blood pressure change and why?
Arterial BP increases because blood viscosity is increased and slows movement.
What happens to the elasticity of arteries in the case of arteriosclerosis? What does that cause?
Elasticity decreases, which causes increased resistance to blood flow, which causes systolic pressure to rise.
What are 8 factors that influence blood pressure.
Age, stress, ethnicity/genetics, gender, medications, daily variation, activity/weight, smoking.
What is normal blood pressure?
<120 AND <80 mmHg
What is considered elevated BP?
120-129 AND <80
What is considered hypertension stage I?
130-139 OR 80-89
What is considered hypertension stage II?
140+ OR 90+
What is considered a hypertensive crisis?
180+ AND/OR 120+
What is considered hypotensive?
When systolic BP is less than 90.
What are some reasons that hypotension may occur?
Dilation of the arteries, loss of a substantial amount of blood, or failure of the heart to pump enough blood.
What is considered orthostatic hypotension?
Drop in systolic by 20, drop in diastolic by 10.
What does a complete blood count show?
Number of RBC and WBC per cubic mm of blood.
What does a high creatine kinase count indicate?
Highly indicative of an MI.
What do cardiac troponins blood studies show?
Troponin I and T levels which can indicate MI’s time line.
Why would a brain natriuretic peptide blood test be done?
To determine severity of heart failure (with increased levels).
What is scintigraphy used for?
Used to evaluate cardiac structure, myocardial perfusion, and contractility.
What does a cardiac catherization do? What is measured?
Helps visualize the cardiac chambers, valves, great vessels, and coronary arteries. Pressures and volumes are measured.
What is the overall purpose of an automated external defibrillator?
To strengthen the chain of survival.
What area of the heart is the SA node found in?
The right atrium.
What begins the electrical conduction of the heart?
The depolarization of the SA node in the right atrium.
What node in the heart stimulates ventricular contraction>
The AV node.
Define perfusion.
Passage of fluid through the circulatory system or lymphatic system to an organ or tissue,
What is cardiac output? What is the equation?
Volume of blood pumped by the heart in one minute. CO = SV x HR.