Anatomical and physiological background knowledge
A physical diagnostic examination of the circulatory system can only be performed adequately if the examiner possesses sufficient knowledge of the anatomy and physiology of the heart and vascular system. For a more detailed explanation the reader is referred to anatomy and physiology textbooks. Only those aspects essential for an adequate execution and interpretation of the physical diagnostic examination will be mentioned here.
Position of the heart in relation to the thoracic wall
The heart is located in the thoracic cavity. Several anatomical reference points are important in indicating the position of the heart. These are briefly listed below [Figure 1]:
- sternum: breastbone
- sternal angle (angle of Louis): angle at transition of uppermost (manubrium) and middle (corpus) parts of the sternum, point where 2nd rib is attached.
- intercostal space (ICS): space between 2 ribs, named after the upper rib. For example, the 3rd ICS is located between the 3rd and the 4th rib.
- midclavicular line: vertical line though the middle of the clavicle (collarbone)
- midaxillary line: vertical line though the middle of the armpit.
Figure 1: Position of the heart with respect to the thoracic wall
1 Clavicle
2 Sternum
2a Manubrrium
2b Sternal angle
2c Xiphoid process
3 Heart
3a Aortic arch
3b Apex
4 Intercatal space
5 Midclavicular line
6 Midaxillary line
Furthermore, knowledge of the anatomy of the heart is needed to interpret the examination. A brief summary is now provided [Figure 2].
Figure 2: Anatomy of the heart
- superior vena cava: the upper vena cava carries blood back to the right atrium
- inferior vena cava: the lower vena cava returns blood to the right atrium
- right atrium (auricle)
- right ventricle (chamber)
- pulmonary trunk (stem of the pulmonary artery)
- left pulmonary artery
- right pulmonary artery
- left pulmonary vein
- right pulmonary vein
- left atrium
- left ventricle
- aorta
- ventricular septum: partition between the left and right ventricle
- tricuspid orifice: transition between the right atrium and right ventricle.
This contains the atrioventricular tricuspid valve. - pulmonary orifice: transition between the right ventricle and the pulmonary
trunk. This contains the semilunar (half-moon shaped) pulmonary valve. - mitral orifice: transition between the left atrium and left ventricle.
This contains the atrioventricular bicuspid valve or mitral valve. - aortic orifice: transition between the left ventricle and aorta.
This contains the semilunar (half-moon shaped) aortic valve.
The following important structures are not shown in Figure 2:
- atrial septum: partition between the left and right atria
- the pericardium: the parietal layer of the heart sac
- the epicardium: the visceral layer of the heart sac
- the sinus node: impulse-generating centre (also referred to as the SA node or Keith-Flack node) situated in the right atrium at the inferior vena cava’s point of entry
- the atrioventricular (AV) node: impulse-generating centre at the transition between the right atrium and the right ventricle (also referred to as the Aschoff-Tawara node)
Aim of the heart examination
To gain an impression of the position, size, rhythm and pumping function of the heart.
Conditions
- Relaxed and familiar atmosphere
- Pleasant ambient temperature
- Adequate lighting
- Physician stands to the right of the patient
- Patient in supine position
- Fully unclothed upper body.