Day 3 — MI, arrhythmias, shock basics

What is a myocardial infarction?

A heart attack caused by decreased blood flow and oxygen to part of the heart muscle.

What usually causes an MI?

A blockage in a coronary artery.

Why can an MI lower cardiac output?

Damaged heart muscle has weaker contractility, so stroke volume and cardiac output can drop.

What are common symptoms of an MI?

Chest pain or pressure, shortness of breath, sweating, nausea, fatigue, pain to the arm/jaw/back, and anxiety.

Why can MI cause shortness of breath?

The heart may not pump effectively, causing poor oxygen delivery or fluid backup into the lungs.

What is an arrhythmia?

An abnormal heart rhythm.

How can a very slow heart rate lower cardiac output?

There are too few beats per minute to pump enough blood forward.

How can a very fast heart rate lower cardiac output?

The ventricles may not have enough time to fill, so stroke volume drops.

Why can an irregular rhythm lower cardiac output?

The heart may not fill or squeeze effectively.

What signs suggest an arrhythmia is unstable?

Low blood pressure, chest pain, shortness of breath, confusion, dizziness, syncope, or weak pulse.

What is shock?

Severe, body-wide poor perfusion where tissues do not get enough blood flow and oxygen.

Why is shock dangerous?

Cells and organs do not get enough oxygen, which can lead to organ failure.

What are common signs of shock?

Low blood pressure, tachycardia, cool clammy skin, confusion, low urine output, weak pulse, increased respirations, and high lactate.

What is hypovolemic shock?

Shock caused by low circulating volume, such as bleeding or severe dehydration.

What is cardiogenic shock?

Shock caused by pump failure, such as a large MI or severe heart failure.

What is distributive shock?

Shock caused by abnormal blood vessel dilation, such as sepsis or anaphylaxis.

What is obstructive shock?

Shock caused by blocked blood flow, such as pulmonary embolism, tamponade, or tension pneumothorax.

How are MI, arrhythmias, and shock connected?

They can all reduce cardiac output or perfusion, causing poor oxygen delivery to organs.

What happens when perfusion to the brain decreases?

Confusion, dizziness, restlessness, or syncope may occur.

What happens when perfusion to the kidneys decreases?

Urine output decreases.