Cardiology and Resuscitation

Heart wall layers

Epicardium (outer layer) protective

Myocardium (middle layer) muscle, pumps blood, thickest in left ventricle cause pumps blood throughout body, acute myocardial infarction affects this layer.

endocardium (inner): innermost lining, smooth surface for blood flow

Heart path

1. Deoxygenated blood enters through superior and inferior vena cava

2. Right atrium

3. Tricuspid valve

4. Right ventricle

5. Pulmonary semilunar valve

6. Pulmonary arteries:Carries blood to lungs to get oxygenated

7. Pulmonary veins:Carries oxygenated blood back to heart

8. Left atrium

9. Bicuspid/mitral valve

10. Left ventricle

11. Aortic semilunar valve

12. Aorta: carries oxygenated blood to arteries which bring it to the rest

Stroke volume vs preload vs contractility vs after load vs cardiac output

• Stroke Volume: Volume of blood ejected in heart after one contraction (70ml is average) depends on:

  • Preload: How much blood returns to heart prior to contraction, how much hearts are filled. Greater its filled greater stroke volume

  • Contractility: How hard heart squeezes (contracts) more forcefully squeezed=more stroke volume

  • Afterload:Function of systemic vascular resistance, how much pressure heart has to pump against to force blood out. Greater the afterload, the lower the stroke volume

• Cardiac Output: Amount of blood ejected from heart in 1 minute

  • Stroke volume x heart rate (pulse) 

  • Slowing heart rate or decreasing volume will decrease cardiac output

  • Increasing heart rate increases the cardiac output, unless its very fast
    (>180BPM) in which case the heart can’t fill up in time and decreases cardiac
    output.

Pulse

• Pulse: forms when left ventricle contracts, sending pressure through arteries, pulse is felt by compressing artery over a bone

BP

• : Force blood exerts against walls of blood vessels, 

  • Systolic blood pressure (top number): each time left ventricle contracts, it forces blood out into circulation, pressure felt on arteries is systolic

  • Diastolic: when left ventricle relaxes, this is pressure remaining  

major arteries (away from heart)

• Arteries begin large, then branch off smaller, the smallest branch is an arteriole

• Coronary arteries: supply heart muscle with blood

• Carotid arteries: neck artery

• Femoral artery: thigh artery

• Aorta: largest artery

• Pulmonary artery: carries deoxygenated blood to lungs

• Brachial artery: upper arm artery

• Radial artery:lower arm

• Posterior tibial artery: side of ankle

• Dorsalis pedis artery:on top of foot

Cardiac conduction system

•  an electrical charge is created, and this energy passes cell to cell. As energy is distributed it spreads to all the cells of the heart and stimulates a mechanical contraction of those cells that squeezes and pushes blood.

• Heart is a muscle and requires constant oxygen and nutrients, receives oxygen from coronary arteries, and has no reserve of oxygen

Acute coronary system signs and treatment

• A blanket term referring to anytime blood supply to cells of heart is blocked or disrupted.

Chest discomfort: as heart cells become ischemic, pain receptors are engaged, not always felt as pain, sometimes as pressure or squeezing or aching. Can be localized or radiate to jaw neck, arms, and upper abdomen. Some don't feel pain at all (common in woman, older, or diabetics)

• Shortness of breath/labored breathing (Dyspnea): common in older and woman

• Nausea/vomiting

• fainting /near fainting (syncope)

• Sudden onset of sweating: many patients think they got flu, but may be denial

• Abnormal pulse: brady/tachy and irregular, palpitations (irregular/rapid they feel as fluttering)

• Abnormal blood pressure: high or low

• Anxiety: impending doom, irritability

• Unusual generalized weakness (older women)

• levine’s sign:clutching chest

nitro if they have any, oxygen, if BP below 90-100 treat for shock, aspirin

ischemia

•  anytime cells are going without adequately oxygenated blood. When it happens cells cant metabolize, impairing function of cells and eventually killing them

  • Some cells like bone and skin can go a long time with ischemia, while cells always working like brain or heart die quickly

coronary artery disease

• Conditions that narrow or block coronary arteries, results in thousands of deaths yearly in US

• Often result of buildup of fatty deposits in inner/middle walls of arteries. These deposits are called plaque. Over time calcium deposits at sight of plaque, causing it to harden

• Risk factors include heredity, age, hypertension, obesity/diet/lack of exercise/smoking. Risk factors other than heredity or age can be reversed,

•  not typically an emergency, but progression creates danger

angina pectoris

• Pain in chest, happens when coronary artery disease narrowed coronary arteries, during times of exertion, portion of myocardium supplied by those arteries are starved, causing angina pectoris

• Symptoms diminish when exertion stops

• Prescribed nitroglycerin is a good sign that they have this

• Hard to differentiate from acute myocardial infarction, can tell dif because acute myo does not resolve on its own, but always assumes acute myo.

• Patients complain of discomfort, dyspnea, nausea, and syncope

acute myocardial infarction (heart attack)

• The condition in which the coronary artery is blocked by the formation of a thrombus or an embolism then blood flow is interrupted and myocardium cells begin to die, can rarely also be caused by an aneurism.

• As plaque accumulates and hardens, it creates weak areas of vessels and makes ruptures possible (aneurysm)

• Occlusion: (blockage of an artery by fatty deposits)

• Thrombus: a clot formed of blood and plaque attached to inner wall of an artery or vein, can cause an occlusion, can also break loose and form an embolism

  • Embolism: blockage of vessel by a clot or foreign material brought to location by bloodstream (tissues beyond blockage can die, which can be fatal)

• Occlusion of blood caused by AMI can cause 2 categories of problems:

• schemia: leads to injury of myocardial cells/death that disrupts electrical function, as cells die, precise route of electrical current that causes rhythmic contractions are disrupted and cause new and deadly patterns of conduction.

• Dysrhythmia: occurs when electricity is distributed abnormally through the heart, causing harmful changes to rate, rhythm, and pumping ability, if a patient dies from a heart attack, normally from a dysrhythmia. 

• Cardiogenic Shock: acute inability of heart to function properly mechanically.  as cells die from hypoxia, function is lost, which affects pumping, rarer than other 2 options, AMI can also affect valves. Multiple heart attacks can also cumulate that diminish function to an unsafe level, . this drops bp dramatically

treatment for AMI

• Most important treatment is transport, do 12 lead ecg, give aspirin/nitroglycerine, dont allow them to talk

• oxygen, position of comfort

Heart failure/congestive heart failure

• Heart failure: also known as congestive heart failure, is progressive condition where the heart is unable to pump blood with normal efficiency. Typically condition implies 1+ of ventricles cant fill/pump adequately. Leads to limited ability to do anything cause of poor perfusion, as well as trouble compensating, can also cause fluid to back up (edema)

• When the ventricle fails to eject an appropriate amount of blood, pressure builds in blood vessels that feed it. If right ventricle fails, pressure builds in right atrium and both vena cavas, 

  • can be seen in jugular venous distention, resulting in pressure of vena cava backing up the jugular veins

  • In high pressure states body attempts to even out pressure by leaching fluid from capillaries, in right sided failure can be seen building in abdomen, resulting from fluid leakage in capillaries by liver

    • Pedal edema:leaking in extremities

• When the left ventricle fails, pressure builds in pulmonary veins, causing pulmonary edema and lessens the ability to diffuse, which can be seen in respiratory distress and presence of crackles.

• Both left and right heart failure can be chronic, left complications are more abrupt, typically after exercise

• Heart failure is not an emergency in itself, signs are same as for pulmonary edema

aneurysm

• stems from weakened sections in arterial walls. In an aneurysm a weakened area of the artery expands and dilates outward under the pressure of normal blood flow, occasionally blood breaks through inner artery lining and goes to middle layers, which further weakens. When an artery bursts, there can be life threatening internal bleeding, as well as poor perfusion to the cells the blood was supposed to be oxygenating. If major artery ruptures, death from shock occurs quickly. 2 most common sites are aorta and brain (causes stroke)

asystole vs v-fib vs v-tach

• Asystole: electric system fails completely, flat line

• Dysrhythmia: disturbance to rate/rhythm. 2 types are ventricular tachycardia (heart so rapid that chambers cannot fill with blood) and ventricular fibrillation (chaotic mechanical response to chaotic electrical activity leads to quivering motion of heart that can't pump blood) happens when electrical dysfunction causes bad electrical distribution through the heart. These lead to sudden arrest

sudden cardiac arrest vs asphyxial cardiac arrest

• Sudden Cardiac arrest: abrupt onset of dysthymia, account for 85% of all arrest situations, most caused by ACS, can also be due to illness, genital heart conditions toxins, and blunt trauma to chest (commotio cordis)

• Asphyxial Cardiac arrest: heart stopped pumping due to issues related to systemic hypoxia. Conditions like respiratory/shock lead to low o2 in blood, causing poor perfusion to myocardial cells. Without proper o2, myocardium becomes ischemic and prone to dysrhythmias. Found in patients with serious illnesses and injuries, , like patients wh0 had severe asthma or shock. 

pediatric cardiac arrest

• Pediatric Cardiac Arrest: most are asphyxial, normally predictable outcomes of decompensation in opposition to adults where arrest is unpredictable and sudden.

Patient Assessment: 

first link of cardiac chain of survival

Recognition and Activation of Emergency Response System (Link 1)

Because it takes a while to reach scene, interventions are normally outside window of cardiac arrest survivability, which is why we need to train civilians, which includes training dispatchers to recognize arrest and begin the bystanders with cpr

2nd link

mmediate High Quality CPR (Link 2)

• Cardio pulmonary resuscitation counteracts arrest. Provider of cpr becomes pump for body and can replace 20% of cardiovascular function

• Key elements of cpr:

  • Hand placement: point of compression should be lower third  of patients' sternum, using heel of hand on victim's chest, and other hand on top so they are overlapping and parallel. For kids one hand or 2 thumb encircling technique.

  • Compression depth: rescuer should press down at least 2 inches and allow time for chest to recoil. For kids should compress one third the anterior posterior diameter of chest (around 1,5 in infants and 2 in children)

  • Compression rate: 100-120 compressions per minute

  • Minimizing pauses: make sure compression fraction (amount of time chest compressions are being performed compared with total time) is above 90% and take steps to minimize pauses, including:

    • Starting cpr immediately

    • Clearing rescuers using aed and not delaying shock for additional clearing

    • Preplanning

    • Transporting only after initial interventions have been performed and were unsuccessful.

    • Training cpr and with tools

  • Rescue breathing: 2 ventilations to 30 compressions with kids, 2:15

• Mechanical CPR: deliver chest compressions at programmed rate, commonly use battery or compressed gas to power. Good because of consistency of rate and depth, as well as never tires. But there is a training curve and it takes a while to set up. There is the LUCAS CPR Device and Zoll AutoPulse.

3rd link

Rapid Defibrillation (Link 3)

• Allows heart to start pumping by correcting dysrhythmias, an Automated External Defibrillator (AED) helps

• AED is a sensor, and uses electrodes connected to the chest to sense different dysrhythmias, and can recognize V-fib and V-tach, and will rarely sense wrong. 

• AED is also a defibrillator, when it finds v-fib/tach, it transfers energy from its battery to the patient, and interrupts dysrhythmias by introducing an external electrical charge. When electricity travels through the heart, it depolarizes the heart cells it touches, which interrupts heart cells electrical function and resets them. The goal of defibrillation is to introduce enough external energy to cause a global resetting of electrical function in the organ.

• 2 dysrhythmias wont work with an aed, asystole (absence of electrical activity) and Pulseless electrical activity (normal electrical activity without mechanical response). For asystole, there is no electrical distribution to reset, and PEA is not an electrical issue, in these cases just do cpr.

• Can be delivered through an AED or manually

• 2 types of defibrillators:

  • Monophasic sends a single shock from the negative pad to the positive pad

  • Biphasic sends the shock first in one direction then the other

link 4 and 5

Basic and Advanced Life Support (Link 4)

• Everyone is important in the cardiac arrest care, each level matters

• Some departments predetermine roles. The triangle of life represents the first 3 providers attending the patient. On either side of patient, one does cpr and other does aed, third at head does ventilations

Advanced Life Support and Postarrest Care (Link 5)

• Return of Spontaneous Circulation (ROSC): The heart is beating again after successful resuscitation, if you can't tell always err on the side of caution and continue cpr.

• If ROSC confirmed shift to postarrest mode, note that the underlying cause of arrest is probably still present, for most adults it is ACS.

terminating resuscitation

• Once you have started resuscitation, you must continue until spontaneous circulation/breathing occurs, another rescuer takes over, you are too exhausted to continue, you receive a cease resuscitation order from a physician. 

  • If you turn a patient over to another rescuer it must be the same or higher level as you.

  • When notifying a family of death, be straightforward and direct, give family time with the deceased,  be patient, don't say you know how they feel, be yourself.

  • Begin Transport When:

    ● ROSC occurs.

    ● 6–9 shocks have been delivered and the patient remains in arrest.

    ● The AED gives 3 consecutive “no shock advised” messages

    separated by CPR cycles.

    ● Termination of Efforts (Considered by ALS/Medical Control):

    ● Arrest was not witnessed by EMS.

    ● No AED shock was ever delivered.

    ● No ROSC was achieved in the field.

cardiac arrest for drowning

• Cardiac arrest for hypothermia and submersion (drowning) injuries:

  • Prolonged cold and dropping body temp change approach to cardiac arrest. 

  • Attempt defibrillation once, then wait till core temp is at least 86 F (30C) before attempting again, if doesnt work transport

  • Because of low body temp, the period of survivability is longer than normal. Hypothermia patients can be transported to places capable of warming while rescuscitating. DO not terminate resuscitation efforts in field

  • For drowning, focus on airway, do not use AED on a soaking wet patient, 

  • Don't defibrillate if anyone is touching the patient, wearing a patch, the patient is wet or touching metal.

cardiac pacemaker

helps keep heart rate normal, placed below clavicles, seen as a small lump, dont put pad over it, if its not working heart may be slow or irregular.

implanted defib

• mini defibrillator in abdomen, shocks patient and can be seen through muscle contractions, if it fails don't place aed over

ventricular assist device

•  mechanical device that pimps blood for heart, left more commonly than right, takes blood out of left ventricle and pumps it to aorta. Provides continuous flow, so the patient will not have pulse or BP. If the patient is unconscious with poor perfusion, they can assume the device is not working and start CPR.

Perfusion triangle

for perfusion to occur, all three components

must function properly. The failure of any one part results in shock

(hypoperfusion).

1. The Heart (The Pump): It should pump blood effectively at an

adequate rate and force.

2. The Blood (The Fluid): There must be sufficient blood volume to

circulate.

3. The Blood Vessels (The Container): The vessels must have

adequate tone (resistance) to maintain pressure.

vagus nerve

A major nerve of the parasympathetic nervous system.

Stimulation of the vagus nerve (e.g., straining during a bowel

movement, severe pain) can cause a “vasovagal response,” leading to a

sudden drop in heart rate and blood pressure, which can result in

dizziness or syncope (passing out).

atherosclerosis

● Atherosclerosis: A disease process where cholesterol, calcium, and

other substances (plaque) build up inside the arteries. This narrows the

arteries, restricting blood flow and creating a rough surface where blood

clots can form, leading to conditions like AMI and stroke.

pulseless electrical activity

Organized electrical activity

is present, but the heart muscle does not contract or resp

cardiac tamponade

Fluid or blood fills the pericardial sac, compressing the heart and preventing it

from filling properly. This leads to obstructive shock.

● Beck’s Triad: The classic signs of cardiac tamponade:

1. Hypotension (due to decreased cardiac output).

2. Jugular Venous Distention (JVD) (due to blood backing up).

3. Muffled Heart Sounds (due to the fluid insulating the sound).

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