Page 203 - ACCCN's Critical Care Nursing

Cardiovascular Assessment
9 and Monitoring

Thomas Buckley

Frances Lin

RELATED ANATOMY
Learning objectives AND PHYSIOLOGY

After reading this chapter, you should be able to: The cardiovascular system is essentially a transport system
● describe the normal blood flow through the cardiovascular for distributing metabolic requirements to, and collecting
system byproducts from, cells throughout the body. The heart
● define each stage of the cardiac action potential pumps blood continuously through two separate circula-
● describe the determinants of cardiac output tory systems: both to the lungs, and all other parts of the
● describe the reasons for the assessment and monitoring of body (see Figure 9.1). Structures on the right side of the
critically ill patients heart pump blood through the lungs (the pulmonary
● summarise the key principles underpinning cardiac circulation) to be oxygenated. The left side of the heart
pumps oxygenated blood throughout the remainder of
assessment and monitoring the body (the systemic circulation). The two systems
1,2
● identify the recommended anatomical landmarks for are connected, so the output of one becomes the input
cardiac auscultation and identify normal and common of the other.
abnormal heart sounds
● describe the physiological bases and reasons for different
types of haemodynamic monitoring CARDIAC MACROSTRUCTURE
The heart is cone-shaped and lies diagonally in the medi-
astinum towards the left side of the chest. The point of
the cone is called the apex and rests just above the dia-
phragm; the base of the cone lies just behind the medi-
astinum. The adult heart is about the size of that
Key words individual’s fist, weighs around 300 g, and is composed
of chambers and valves that form the two separate pumps.
cardiovascular macrostructure The upper chambers, the atria, collect blood and act as a
coronary perfusion primer to the main pumping chambers, the ventricles. As
cardiovascular electrophysiology the atria are low-pressure chambers, they have relatively
cardiovascular assessment thin walls and are relatively compliant. As the ventricle
heart sounds propels blood against either pulmonary or systemic pres-
electrocardiography sure, they are much thicker and more muscular walls than
the atria. As pressure is higher in the systemic circulation,
haemodynamic monitoring the left ventricle is much thicker than the right ventricle.
chest X-ray Dense fibrous connective tissue rings provide a firm
diagnostic imaging anchorage for attachments of atrial and ventricular muscle
and valvular tissue. 1,4
One-way blood flow in the system is facilitated by valves.
Valves between the atria and ventricles are composed of
INTRODUCTION cusps or leaflets sitting in a ring of fibrous tissue and col-
lagen. The cusps are anchored to the papillary muscles by
This chapter reviews the support of cardiovascular func- chordae tendinae so that the cusps are pulled together
tion in the face of many compromises to the system. It is and downwards at the onset of ventricular contraction.
essential that the reader has a thorough knowledge of The atrioventricular valves are termed the tricuspid valve
both electrical and mechanical functions of the cardiac in the right side of the heart and the mitral or bicuspid
system. Methodology for assessment of cardiovascular valve in the left side of the heart. Semilunar valves prevent
elements are discussed, along with best practice ideas and backflow from the pulmonary artery (pulmonic valve)
180 diagnostic techniques. and aorta (aortic valve) into the right and left ventricles