Exam 3 -- Cardiovascular System Flashcards
What are the ocular signs or symptoms that can accompany cardiovascular disease?
Retinal artery or vein occlusion, macroaneurysms, TIA, retinopathy, ocular ischemic syndrome
What are some of the roles of vascular endothelium?
Blood tissue permeability, coagulation/clotting control, vessel repair, blood flow modulation, inflammation and cell growth regulation, oxidation of LDL
True or false: the heart valves have muscles to aid in blood passage through the heart
False; they work on a passive basis
Name the four valves of the heart in the order in which the blood passes through them, along with the structures each valve separates
Tricuspid valve (blood from right atrium –> right ventricle), pulmonic valve (blood from right ventricle –> pulmonary artery), bicuspid/mitral (blood from left atrium –> left ventricle), aortic valve (blood from left ventricle –> aorta)
Normal heart rate is 60-100 bpm. Above 100 bpm is called _______________, below 60 is called _______________
Tachycardia, bradycardia
Systole is contraction of the walls of the ventricles to empty the heart of blood. Which valves are closed during systole?
Mitral and Tricuspid (heart is eMpTying)
Which heart sound corresponds to the closing of the mitral and tricuspid valves?
S1
What is preload? Within limits, what does increased preload do? What is this relationship called?
Amount of blood in the ventricle at the end of diastole (end diastolic volume, EDV). Increased preload (within limits) stretches the ventricle more, which leads to a more rapid and forceful ventricle contraction. This is called the Frank-Starling relationship. (Think of ventricle as a rubber band: more stretch = more energy = further distance when shot; but if too much stretch would not be good.)
What is afterload? What factors affect it?
The force against which ventricles must contract to eject blood. Arterial pressure is the main factor, but thickness of blood and vessel elasticity (among other things) play a role too. (More elastic vessels = decreased afterload = easier to push blood out; think of as a new balloon, which is less elastic than an old balloon; you, the heart, would have to work harder to fill a new balloon than an old balloon)
Contracility is the force of ventricular contraction. It is independent of loading conditions. Calcium and beta-blockers affect contractility.
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What is a normal value for cardiac output?
5-6 L/min
Cardiac index is cardiac output divided by body surface area. What range is the normal range of values?
2.6-4.2 L/min/square meter
Briefly describe conduction of electrical impulses in the heart, starting with the SA node.
SA node fires, sending signals simultaneously to AV node and left/right atria. The atria contract; AV node delays the signal slightly before sending it on through the bundle of His. Bundle of His separates into right and left bundle branches, which each become Purkinje fibers and cause the ventricles of their respective sides to contract.
The sympathetic nervous system affects heart rate and contractility. How does this occur?
It stimulates beta-1 receptors of SA and AV nodes, causing them to pass signals along faster (increased heart rate), also shortening conduction time through the AV node. It also innervates the atria/ventricles and increases their contractility by increasing calcium concentration
The parasympathetic nervous system affects heart rate and contractility. How does this occur?
It decreases heart rate through the nodes. Through the vagus nerve it also innvervates the atria but not the ventricles, causing only a slight decrease in contractility
The atrial and ventricular myocytes form two syncytia. What is this and what does mean?
The cell membrane of the myocytes are fused together, meaning that if one of them depolarizes, they all depolarize. This allows them to all contract together (important for regular heart beats.
Contractility of heart muscle is increased by what?
Increased free (unbound) calcium
Relaxation of heart muscle depends on removal of calcium from the myocyte cytoplasm. How does this occur?
Through exchange with sodium (sodium in for calcium out) and through uptake into sarcoplasmic reticulum and mitochondria
Name a medication that interferes with the sodium-potassium pump in the heart. What effects (including side effects) does this drug have?
Digitalis; slows HR (through delayed AV node signal conduction), increases contractility (through increased inctracellular calcium). SE include blurred vision, color perception alteration, halos on dark objects
Name a medication that interferes with calcium channels in the heart. What effects does this drug have?
Verapamil; decreases afterload (through vasodilation of vascular system via delayed calcium influx into vascular smooth muscle); decreases contractility; delays removal of calcium from pacemaker cells, thus slowing HR (through interfence of SA/AV node repolarization)
What class of medication interferes with the autonomic nervous system innervation of the heart by blocking epinephrine? What is the result of this blockage? You wouldn’t want to use this class of drugs in patients with what type of condition?
Beta-blockers; these decrease HR and contracility. They also slow conduction time, so you wouldn’t want to use them in a patient with severe heart block (their heart rate is already too slow).
Serum enzyme tests are done to detect enzymes released by dying heart muscle. Creatinine phosphokinase (CK-MB), lactate dehydrogenase (LDH-1), and troponin I are three such tests. Levels of these substances start increasing how long after the myocardial infarction (MI)? When do levels peak? When do they return to normal?
CK-MB: increased 2-6 hours after, peak at 12-24 hours, normal in 3 days; LDH-1: increased in 24-72 hours after, peak at 2-5 days, normal in 14 days; Troponin I: increased 4-6 hours after, peak at 10-24 hours, normal in 10-15 days
Of the serum enzyme tests, which is probably most specific?
Troponin I
An EKG doesn’t indicate anything about heart disease; it only analyzes the electric circuitry of the heart. How many peaks/deflections should show on a normal EKG? What is indicated by each peak?
5 peaks: P (atrial cell depolarization), QRS (ventricle depolarization), and T (ventricular repolarization). [FYI: PR interval measures AV conduction time, or the time from the onset of atrial depolarization to the time of onset of ventricular depolarization.]
What is the purpose of a stress test?
A stress test determines the heart’s response to physical exertion by measuring ECG, BP, and pulse during exercise. Changes in the ECG during the exercise as compared to rest indicate presence and severity of the ischemia.
True or false: cardiac catheterization is used to detect pressures and patterns of blood flow.
True. You can also inject contrast for angiography
A coronary calcium scan is a CT used to evaluate calcium buildup in coronary arteries. Generally, people with risk but no symptoms are evaluated with this test. What is the range of possible scores on this test? What kind of score is more likely to be indicative of coronary artery disease?
Score range: 0-400; greater than 100 means likely to have CAD
Ultrasonography shows structure and movement of the heart, and doppler is a special form of ultrasonography used for blood vessels to show bloodflow.
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Multiple-gated acquisition scan (MUGA scan) is a radioactive test. What part of the heart is monitored, and what is being measured?
The left ventricular wall is monitored for the left ventricle’s ability to eject blood. This tests the function of the heart and the heart’s cardiac output
Stress thallium (DIP-thal) is a test that involves injection of thallium 201. It is used to image the heart. What types of tissue take up the radioactive thallium?
Healthy myocardial tissue, but not infarcted or scarred tissue, and not blood.
Define: arrhythmia
Irregularity in rate or rhythm
Cardiac arrhythmias can be accompanied by several symptoms. What are some of these symptoms?
Palpitations, dizziness, lightheadedness, syncope, anxiety, chest or neck discomfort, dyspnea, weakness.
True or false: cardiac arrhythmias are always accompanied by some amount of lightheadedness
False; arrhythmias can in fact be asymptomatic.
Diagnosis of arrhythmias may involve case history, clinical exam, EKC, echocardiogram, even monitor, and what other type of device?
Holter monitor (24-48 hour time period in which patient wears the device and it monitors for irregularities of heart beat)
What are different ways an arrhythmia could be classified?
Tachyarrhythmia (too fast) vs. bradyarrhythmia (too slow); supraventricular (atrial or nodal) vs. ventricular; regular vs. irregular
How would you describe the heartbeat of a patient with a regular arrhythmia?
One that is either too fast or too slow, but still a predictable beat with the two heart sounds.
How would you describe the heartbeat of a patient with a irregular arrhythmia?
The beat is still predictable but the heart sounds are abnormal (could be three heart sounds, for example).
How would you describe the heartbeat of a patient with a irregularly irregular arrhythmia?
The rhythm is completely unpredictable.
Sinus tachycardia is due to an increased rate of the SA node. It can be caused by exercise, fear, fight, stress, etc (due to catecholamine release). What are some diseases or conditions that might cause sinus tachycardia?
Anemia, hyperthyroidism, heart failure
How would you treat sinus tachycardia?
Treat the underlying condition (i.e., treat the hyperthyroidism, if that is the cause) or use a med that slows AV node: beta blockers or calcium antagonists.
Atrial fibrillation is the most common sustained rhythm disturbance and is what type of arrhythmia? (i.e., regular, irregular, or irregularly irregular)
Irregularly irregular
The constant depolarization of the atria in atrial fibrillation is based down to the ventricles as well, though these beat at a much slower rate. (Atria = 300-600 bpm, ventricles = 120-170 bpm). Where does the signal come from causing the constant atrial depolarization?
Usually near the pulmonary vessels
What are the three “classic” causes of atrial fibrillation? What are the most common causes of atrial fibrillation?
Rheumatic heart disease, excessive alcohol, and thyrotoxicosis are the “classic” causes but aren’t very common due to these conditions being treated before they tend to cause fibrillation. Hypertension and heart failure are the most common causes.