Diseases of the cardiovascular system frequently confront the physician
involved in the day-to-day care of patients. Knowledge of the underlying
pathophysiologic processes associated with diseases of the heart
and blood vessels provides a critical framework for patient management.
This chapter deals with diseases of the heart and the next one with
diseases of the blood vessels. Normal cardiac structure and function
are summarized here, and pathophysiologic mechanisms for commonly
encountered cardiac problems are then discussed, with emphasis on
arrhythmias, congestive heart failure, valvular heart disease, coronary
artery disease, and pericardial disease.
The heart is a complex organ whose primary function is to pump
blood through the pulmonary and systemic circulations. It is composed
of four muscular chambers: the main pumping chambers, the left and
right ventricles, and the left and right atria, which act like “priming
pumps” responsible for the final 20–30% of
ventricular filling (Figure 10–1A).
Peripheral venous return from the inferior and superior venae cavae
fills the right atrium and ventricle (through the open tricuspid valve)
(Figure 10–1B). With atrial contraction,
additional blood flows through the tricuspid valve and completes
the filling of the right ventricle. Unoxygenated blood is then pumped to
the pulmonary artery and lung by the right ventricle through the
pulmonary valve (Figure 10–1C).
Oxygenated blood returns from the lung to the left atrium via four
pulmonary veins (Figure 10–1D).
Sequential left atrial and ventricular contraction pumps blood back
to the peripheral tissues. The mitral valve separates the left atrium
and ventricle, and the aortic valve separates the left ventricle
from the aorta (Figures 10–1D and 10–1E).
Anatomy of the heart. A: Anterior view of
the heart. B: View of the right heart with the right
atrial wall reflected to show the right atrium. C: Anterior
view of the heart with the anterior wall removed to show the right
ventricular cavity. D: View of the left
heart with the left ventricular wall turned back to show the mitral
valve. E: View of the left heart from the left side
with the left ventricular free wall and mitral valve cut away to
reveal the aortic valve.
(Redrawn, with permission, from Cheitlin MD,
Sokolow M, McIlroy MB. Clinical Cardiology, 6th
ed. Originally published by Appleton & Lange. Copyright © 1993
by the McGraw-Hill Companies, Inc.)
The heart lies free in the pericardial sac, attached to mediastinal
structures only at the great vessels. During embryologic development,
the heart invaginates into the pericardial sac like a ...