Heart block
Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissue, with the other two being skeletal muscle and smooth muscle. It is involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle (myocardium) forms a thick middle layer between the outer layer of the heart wall (the pericardium) and the inner layer (the endocardium), with blood supplied via the coronary circulation. It is composed of individual cardiac muscle cells joined together by intercalated discs, and encased by collagen fibers and other substances that form the extracellular matrix.
Essential echocardiography : A practical guide
A Practical Handbook serves as today's premier practical guide to the understanding of the most commonly used cardiac imaging technique in the world. The perfect marriage between anatomy and physiology, the text covers emerging cardiac imaging technologies, advances in ultrasound technology, as well as new techniques and applications of cardiac ultrasound. Essential Echocardiography: A Practical Handbook provides the physiological, anatomical, and diagnostic grounding for all students of cardiac ultrasound, as well as a sound basis for a more general understanding of cardiac imaging.

