Status Objectivus II: Auscultation And Determination Of Murmurs In Examining The Heart
Stethoscope in Use
The modern convntional stethescope has the bell and the diaphragm. The former picks up low-pitched sounds better, whereas the latter is more useful to receive high-pitched sounds. The mitrial, tricuspid, pulmonary and aortic areas are auscultated in order and then the third left intercostal space (second aortic area) is auscultated. Several additional areas of the chest or body have also to be auscultated, when there are indications.
These include the interscapular area, neck, first and second left intercostal spaces, apices of lungs, abdomen, spine and head. Normal heart sounds, additional sounds such as third and fourth heart sounds, clicks and murmurs and pericardial rub are specially looked for. In general, the events occurring at the different valves are heard best over the corresponding areas.
The second sound in the pulmonary area shows two components-the aortic and the pulmonary (A2 and P2). Normally, during inspiration, the pulmonary component becomes delayed whereas the aortic component occurs slightly earlier and S2 becomes split. In expiration, both the components merge and S2 becomes single. This variation does not appear in disease. Splitting of the second sound is called fixed, if it does not show a variation between inspiration and expiration. This happens in atrial septal defect and right ventricular failure.
In atrial septal defect, both the ventricles share a common atrial reservoir and this leads to equal delay of A2 and P2 in inspiration. Inability to vary its stroke volume by the failing right ventricle accounts for the fixed splitting of S2 in right ventricular failure. If the splitting of the second sound becomes narrow during inspiration, it is called reversed split (Paradoxical split). This occurs in aortic stenosis and left ventricular failure.
Gallops are diastolic events and appear to be related to two periods of filling of the ventricles, namely the ventricular diastolic gallop occurring during the rapid filling phase and the atrial gallop occurring during the pre-systolic filling phase due to atrial systole. The former is an early sign of ventricular dysfunction.
Auscultation of Murmurs
These are produced by turbulence of blood flow at or near the valves or through abnormal communications. If a murmur occurs as a result of abnormally large amount of blood flowing through a normal valve, or due to valve-ring dilatation, this is termed functional murmur. This disappears when the hemodynamic abnormality is corrected. On the other hand, organic murmurs are produced by the abnormality in the heart or blood vessels and these murmurs tend to persist. In addition to its sites, several characteristics of the murmur help in identifying it source. These are:
- the timing,
- character (high pitched, low pitched, etc)
- response to maneuvers like hand grip valsalva and squatting.
Extra-cardiac adventitious sounds are venous hum, bruit over arteries, pericardial rub and pleuropericardial rub.
Using the right Blood pressure Cuffs
Recording of blood pressure
The appropriate sized cuff for adults and children has to be used, otherwise the values will be altered. It is ideal to use mercury Sphygmomanometers. If aneroid instruments are used, their accuracy should be verified periodically. The blood pressure should be recorded in both arms and legs, when arterial occlusion is suspected. The systolic pressure in the lower limb is 20-30mm higher than in the upper limb. Though the point of muffling of Korotkoff sounds denotes the diastolic blood pressure, to achieve consistency in recording, the point of disappearance of these sound can be accepted to represent the diastolic blood pressure for clinical purposes.
© 2013 Funom Theophilus Makama