What to listen for?

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According to the American Academy of Family Physicians (AAFP) distinguishing between pathological and benign (innocent) cardiac murmurs is perhaps the most challenging aspect of a physical examination. It is recommended that patients with signs or symptoms of a pathological murmur should be referred to a cardiologist.

This is even more true when making decisions during a pre-participation, school, college or DOT physical. When making eligible and disqualifying decisions, it is important to follow current clinical guidelines. Practitioners are often under pressure to clear a person for a certain activity, or may rush the exam, because no symptoms are presented.

Benign (functional, innocent or physiological) murmurs occurs in the absence of a cardiac structural abnormality with no symptoms or family history. The S2 sound pulse has a normal, physiological split, best heard at the pulmonary and there're no clicks or gallops. The murmur is usually early to mid-systolic with a musical, vibratory, or buzzing quality. And it is soft, grade two or lower.

The next image shows the relative mid-range energy distribution of the average heart beat for a patient with a benign murmur. The relative energy levels for the S1/S2 sound pulses, early-, mid- and late systole and diastole are also indicated. Note the relative low energy levels within the early and mid-systolic region. Typical for a benign murmur.

 Innocent Cardiac Murmurs

Pathological cardiac murmurs evolve from from structural abnormalities within the heart or greater vessels. These murmurs are usually loader (grade 3 or more), longer in duration, could be harsh and may change with various manoeuvres. Sometimes it's associated with an arrhythmia or an abnormal pulse. A diastolic murmur is always associated with a pathology.

The next image shows the energy distribution of a murmur due to pulmonic valve stenosis (PVS). Although there's a correspondence with the functional murmur in energy distribution (early systolic, ending before the S2 sound), the sound quality of the PVS will be more harsh.

PVS Murmur

The next image is an example of a murmur due to a VSD. This is a load, harsh pan-systolic murmur (above grade 3) which could easily be diagnosed with a stethoscope.

VSD Murmur




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