Approach to the Exam for Diastolic Murmurs

Diastolic murmurs are always a pathological finding on the auscultation of the heart, indicating the presence of a valvular abnormality. The physical exam can, by itself, reveal the cause of a diastolic murmur. However, it is very important to perform the physical exam with the right technique in order to maximize our chances to identify a diastolic murmur and determine its cause. On this page we will review the four most common types of diastolic murmurs with a particular focus on their causes and the best approach to the physical exam. We will also briefly review some of the most common causes for a continuous murmur. 

There are multiple causes for aortic regurgitation. One approach to classify them could be to differentiate between acute and chronic processes. The most important causes of acute aortic regurgitation are infective endocarditis and aortic dissection. Instead, the most common causes of chronic aortic regurgitation are aortic root dilation secondary to chronic hypertension and calcific degenerative aortic valve disease.

Auscultation technique

The murmur of aortic regurgitation is loudest at the left lower sternal border, around the 3^rd and 4^th intercostal spaces. Also, any maneuver that brings the heart closer to the chest wall will increase the intensity of this murmur. To do this, the best approach is to ask the patient to sit upright on the examination table, lean forward and hold the breath in full expiration. If the diastolic murmur is caused by aortic regurgitation it should increase in intensity with these maneuvers.

Pulmonary regurgitation is a relatively rare cause of a diastolic murmur, and it is usually due to either infectious endocarditis or pulmonary hypertension. In the first case, there is direct damage to the valve leaflets caused by an infectious process. In the second case, instead, there is a dilation of the pulmonary artery root that causes the valve to become incompetent.

Differentiation from aortic regurgitation

The diastolic murmur of pulmonary regurgitation is very similar to the one of aortic regurgitation. It is a decrescendo diastolic murmur with a blowing character. However, contrary to the one of aortic regurgitation, this murmur is loudest at the left upper sternal border, around the 2^nd and 3^rd intercostal spaces. Because of their similarity, it can be very difficult to differentiate between these two murmurs relying on auscultation alone. The key differential element is the presence of a peripheral arterial bounding pulse, that only patients with aortic regurgitation will demonstrate.

One of the most common causes of a diastolic murmur is mitral stenosis. It is the most common manifestation of rheumatic heart disease, which is also the main etiology of mitral stenosis. Other less frequent causes of mitral stenosis are atrial myxoma, calcific annular degeneration of the mitral valve and congenital causes, which are seen mostly in the pediatric population.

Tricuspid stenosis is the rarest of all causes for a diastolic murmur. Usually, it is found in patients with rheumatic heart disease. In this case, the patients will also have either mitral valve disease, aortic valve disease or both, making it hard to appreciate the murmur of tricuspid stenosis. The most important cause of isolated tricuspid stenosis is instead carcinoid syndrome.

It is important to differentiate diastolic and systolic murmurs from continuous murmurs, that are heard both in systole and in diastole. We will briefly describe two of the most common causes of a continuous murmur, that are the patent ductus arteriosus and pericarditis.