Cardiovascular system

Question 1

How much blood does the heart pump every minute?

Answer 1

5L (amounts to 7000-9000L/day)

Question 2

What are the 3 layers of the heart? Provide a small description of each.

Answer 2

1. Epicardium: Outer layer with vasculature
2. Myocardium: Middle, muscly layer
3. Endocardium: Inner, smooth layer that also forms the valves

Question 3

What is the function of the SA node of the heart?

Answer 3

The primary electrical impulse generator in the heart (pacemaker).

Question 4

What is the function of the bundle of His in the internodal electrical pathway of the heart?

Answer 4

To slow the electrical impulses originating from the cardiac pacemakers, staggering muscle contraction.

Question 5

With regard to the propagation of electrical impulses in the heart, what is the difference between the absolute refractory period and the relative refractory period?

Answer 5

Absolute: cannot generate a new electrical impulse. insufficient charge across the cell membranes.
Relative: difficult to generate a new electrical impulse. Requires extra ions to flow across the cell membranes to reach the threshold for firing.

Question 6

With regards to heart contraction, what is “preload”?

Answer 6

The amount of blood present in the ventricles immediately before contraction.

Question 7

With regards to heart contraction, what is “afterload”?

Answer 7

The amount of pressure that the ventricles must exert to overcome the resistance in the vascular system and expel blood from the heart during contraction.

Question 8

What is Frank Starling’s law with regard to heart contractility?

Answer 8

If the heart detects increased volume in the ventricles (sensed by stretching of the muscles) it will contract with greater force to expel that increased volume.

Question 9

What is the function of ACE-inhibiting medication? How does it do this?

Answer 9

To lower blood pressure through inhibition of a part of the RAAS system.

Question 10

What is the function of Beta-blocking medication? How does it do this?

Answer 10

To lower blood pressure by blocking the effects of epinephrine.

Question 11

What is the function of calcium channel blocking medication? How does it do this?

Answer 11

To lower blood pressure by limiting the amount of calcium that can flow into the heart and initiate contraction.

Question 12

What is atherosclerosis?

Answer 12

A narrowing of the large arteries due to plaque buildup which can break free and cause emboli.

Question 13

What is causing the pain felt during angina?

Answer 13

The buildup of lactic acid in the coronary arteries due to trapped blood and lack of O2 reaching the tissues.

Question 14

What causes Prinzmetal’s Angina? What makes it most significantly different from typical, stable angina?

Answer 14

Temporary spasms of coronary vessels usually occurring near an area of severe atherosclerosis. It is different from stable angina in that it almost always occurs while the person is at rest.

Question 15

What causes stable angina? What normally provokes an exacerbation of stable angina?

Answer 15

A narrowing of a coronary artery (atherosclerosis) without the formation of a blood clot at the narrowed area. Usually provoked by exertion.

Question 16

What causes unstable angina? What normally provokes the pain felt in unstable angina?

Answer 16

A narrowing of a coronary artery (atherosclerosis) in which a blood clot forms at the narrowed area. Provoked by exercise or exertion.

Question 17

Give at least 2 mechanisms which could cause myocardial infarction.

Answer 17

Any of:
- Atherosclerosis
- Rupture of vessels
- Angina
- Severe hypoxia
- Shock

Question 18

What causes the pain felt when a person is experiencing a myocardial infarction?

Answer 18

Lack of O2 causes cells to switch to anaerobic metabolism and build up lactic acid in the coronary arteries. Eventually, tissue death occurs distal to the occlusion.

Question 19

Define congestive heart failure, in general.

Answer 19

The inability of the heart to meet the demands of the body. Whether because the demands of the body are increased or the output of the heart is decreased.

Question 20

Your patient is presenting with dyspnea, cyanosis, hypertension, and tachycardia. They are coughing up frothy pink sputum. on auscultation you hear crackles in their lungs. What condition are they likely experiencing?

Answer 20

Left ventricular failure. The ventricle is unable to expel all the blood, overflows, and backs blood up into the pulmonary circulation. This causes plasma/blood to seep into the alveoli.

Question 21

List at least 2 signs and symptoms of right ventricular failure.

Answer 21

Right ventricular failure (Cor Pulmonale) can present with:
- Jugular vein distension
- Enlarged liver/spleen
- Peripheral edema
- Weight gain
- Increased peripheral venous pressure
- Fatigue
- GI disruption
+ Any others you can justify

Question 22

What is the cutoff for blood pressure, above which is considered hypertension?

Answer 22

BP consistently greater than 140/90 mmHg.

Question 23

Describe atrial fibrillation, in general terms.

Answer 23

The contraction of the atria and the ventricles of the heart are not coordinated. This can cause bradycardia, tachycardia, or irregular HR.

Question 24

Describe pericardial tamponade, in general terms.

Answer 24

The pericardium fills with fluid, putting pressure on the heart and reducing its ability to pump blood.

Question 25

List at least 2 signs and symptoms of pericardial tamponade?

Answer 25

Any of:
- Chest pain
- Tachycardia
- Jugular vein distension
- Decreased systolic blood pressure (late stage)
- Pulsus paradoxes
- Faint or muffled heart sounds

Question 26

What is an aneurysm? What are they generally caused by?

Answer 26

A dilation or bulging of a blood vessel. Could be caused by atherosclerosis, infectious diseases, trauma, or genetic disorders.

Question 27

Your patient complains of a “ripping, tearing, 10/10 pain” in their chest. They have unequal radial pulses, reduced LOC, and are peripherally cyanosed. What condition is causing this?

Answer 27

Dissecting aortic aneurism. Can present as thoracic or abdominal pain depending on the location of the abdomen and may be anterior or posterior on the body.

Question 28

A patient complains of “numbness and pain” in their lower R leg. On inspection, you notice that their R leg appears cyanotic and you aren’t able to find a distal pulse. They have no apparent injuries. What is the likely cause of this presentation?

Answer 28

Likely there is an arterial occlusion preventing blood from reaching the extremity. This could be an embolus or thrombosis in the absence of trauma.

Question 29

What is endocarditis? Is this something that we are likely to detect in the pre-hospital environment?

Answer 29

Infection and subsequent inflammation of the endocardium (inner lining of the heart and heart valves). Requires hospital facilities to identify accurately, presents as idiopathic chest pain pre-hospital.

Question 30

What is myocarditis? What will patients present like in the pre-hospital environment?

Answer 30

Inflammation of the myocardium as a response to injury or infection. Will present as chest pain, dyspnea, fatigue, fever, and arrhythmias.

Question 31

What is pericarditis? What will patients present like in the pre-hospital setting?

Answer 31

Inflammation of the pericardium due to viral infection, kidney failure, MI, tumours, etc. Will present as chest pain, dyspnea, fever, pericardial effusion potential leading to pericardial tamponade.