Skip to ContentGo to accessibility pageKeyboard shortcuts menu
OpenStax Logo

The heart with the main arteries and veins.
Figure 22.1 The heart is the primary organ of the cardiovascular system, controlling circulation and blood flow for the entire body. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Cardiac emergencies are life-threatening events that can include acute myocardial infarction, unstable angina, and acute dysrhythmias (abnormal heart rhythms). Acute myocardial infarction and unstable angina occur when the blood supply to the heart is threatened by occlusion of a coronary artery. Both of these processes of cardiac tissue ischemia deprive the tissue of oxygen; in infarction, cell death has occurred in the tissue as a result of this sudden insufficient blood supply. Ischemia and infarction can acutely and significantly affect the heart’s ability to pump blood. Dysrhythmias occur when the cardiac conduction system is not functioning correctly and so does not stimulate the heart to contract correctly. Both coronary artery occlusions and acute dysrhythmias can lead to shock, which occurs when tissue perfusion is decreased so much that tissues become ischemic. If shock is not reversed quickly, tissue damage will occur, and eventually cell, tissue, and system death will occur.


This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute OpenStax.

Attribution information
  • If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
    Access for free at
  • If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
    Access for free at
Citation information

© May 15, 2024 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.