D. Heart and blood vessels Chapter V Thorax D. Heart and blood vessels Heart by Dr. Zhuo-ren Lu
I. Inspection l Observe protrusion of precordium and apical impulses with tangential lighting. Check other pulsation in the anterior chest. l The normal impulse is located generally in the fifth intercostal space, 0.51cm within the midclavicular line.
l An abnormal position of impulse generally indicates cardiac enlargement, but the causes of cardiac displacement such as scoliosis, funnel sternum, pleural effusion and pulmonary fibrosis, a big mass in abdominal cavity should be eliminated. l Left ventricular hypertrophy results in downward (6th space) and outward displacement of the apex beat. Right ventricular hypertrophy causes strong pulsation under the xiphoid or/and a change of apex beat in position towards left (5th space). l A feeble diffuse impulse ( more than 22.5cm in diameter) may suggest dilation. If the thrust is forcible, hypertrophy is suggested.
II. Palpation 1. The hand should then be placed on the all areas of the precordium in order to detect any abnormal pulsation, vibrations or thrill, and pericardium friction rub. 2. The pulsation of the abdominal aorta may often be felt in the epigastric area. Also, the impulse from right ventricle can be felt by the fingertips placed under the xiphoid process while inspiration.
3. Thrill A thrill is a palpable murmur from the heart or great vessels. The main reason is the obstruction to blood flow through a narrowed valve or the certain abnormal congenital defects. Thrills may be systolic, diastolic or may occur continuous in time. l In aortic stenosis and aneurysm of the great vessels at the root of the neck, a powerful systolic thrill may be palpable over the 2nd interspace, usually spreading upwards to the neck. l To the left of the sternum in the 2nd interspace, pulmonary stenosis gives rise to a similar systolic thrill.
l In the left 3rd or 4th parasternal area, systolic thrills are due to congenital lesions of the interventricular septum of heart. l Diastolic thrills at the apex are usually due to mitral stenosis. l The combination of a systolic and diastolic thrill occurs over the base of the heart in patients with patent ductus arteriosus. l Timing a thril is best accomplished by either the apex beat or the carotid artery palpation, both of which correspond to ventricular systole.
4. Pericardial friction rub Pericardial friction rub is caused by a fibrinous pericarditis. l It is present during both phases of the cardiac cycle. In the presence of pericardial effusion the rub will disappear because of the separation of the visceral and parietal layers by the fluid. lOften rubs are more readily palpated with sitting erect and leaning forward. l They are best palpated in the left 3rd and 4th intercostal spaces at the sternal border.
III. Percussion l Percussion of cardiac dullness border starts to the left on the chest, from 23cm apart from the apical impulse towards cardiac dullness (relative cardiac dullness). Percussion is performed from left towards cardiac dullness in the 4th, 3rd and 2nd intercostal spaces. Next, to the right of the chest, percussion is done in the midclavicular line down to a dull point (the upper margin of liver). Then, percuss from right towards cardiac dullness in the 4th (above the liver dullness), 3rd, and 2nd intercostal spaces.
l Measure the vertical distances from each point of cardiac dullness to the mid-sternal line with a stiff ruler. l When the left border of cardiac dullness falls outside the midclavicular line, it usually indicates that the left ventricle is enlarged. l If the left border of cardiac dullness goes out of left midclavicular line (the left cardiac border towards left in the 5th intercostal space), it suggests that the right ventricle enlarged. l The cardiac dullness enlarged towards two sides: (1)both left and right ventricles enlarged, (2) a large volume of fluid in the cavity of pericardium. In this case, the cardiac borders will be changed following the change of the patient's position.