Heart Murmur, Diastolic
David E. Anisman and Gerald F. Farnell
A diastolic murmur is a finding that provides a clue to an underlying disease process. Unlike their systolic counterparts (Chapter 7.7), diastolic murmurs almost always indicate underlying heart disease.
Approach
Given the broad range of factors that may cause diastolic murmurs, a two-part scheme is used to narrow the differential diagnosis. First, the timing of the murmur (early, mid-, or end-diastolic) helps in localizing the anatomic abnormality to a specific valve or other heart structure. Second, historical features such as congestive heart failure, rheumatic disease, congenital abnormalities, or connective tissue and collagen vascular disease further characterize the underlying cause.
History
A. Symptoms. Many patients with diastolic murmurs will not present with specific complaints; rather, the murmurs will be found in the course of a routine medical examination. With symptomatic lesions, the patient may experience dyspnea, chest pain, or palpitations. Pulmonary regurgitation (PR) is usually asymptomatic except in its most severe forms. More specific symptoms include chest or neck pounding in aortic regurgitation (AR); hemoptysis, embolism, or hoarseness (left recurrent laryngeal nerve compression from the left atrium) in mitral stenosis (MS); failure to thrive or frequent respiratory infections with congenital MS; edema in tricuspid stenosis (TS); and fever, anemia, weight loss, embolism, digital clubbing, arthralgias, syncope, rash, and Raynaud’s phenomenon with an atrial myxoma (1).
B. Past medical history. Does the patient have a history of rheumatic fever (RF)? RF is the most common cause of all diastolic murmurs (mitral → aortic → tricuspid → pulmonic) (2). Of patients with mitral stenosis, 50% will have a history of rheumatic fever (3).
1. Endocarditis. Vegetations can lead to either AR/PR or MS/TS.
2. Pulmonary hypertension with PR is classically associated with the Graham Steell murmur, heard in the left third interspace near the sternum and propagated down the sternum.
3. Connective tissue and collagen vascular diseases predispose to aortic root dilatation and AR.
4. Congenital heart malformations can be associated with multiple valvular lesions, left ventricular (LV) outflow tract abnormalities, or shunts (with resultant volume overload).
5. Atrial myxoma is a rare cause of variable AV valve obstruction.
6. Syphilis can cause aortitis and AR.
Physical examination (PE)
A. Table 7.3 lists characteristic PE findings of diastolic murmurs.
B. Fine points of the physical examination
1. Is the murmur of AR louder at the right sternal border? If so, consider aortic root dilation. Remember, whereas the duration of the chronic AR murmur is directly proportional to the severity of the regurgitation, the duration of the acute AR murmur may not predict its severity (3).
2. Is the murmur of MS shorter, or does it extend closer to S2? The length of this murmur, not its intensity, is directly proportional to the severity of the stenosis (3). In addition, the murmur may not be audible with increased heart rates because of shortening of diastole.
3. Does the murmur of MS vary from examination to examination? If so, and especially if it is introduced by a “plop” sound, consider atrial myxoma.
Testing
Echocardiogram is the essential test for confirming the anatomic location of the murmur and its severity. Transthoracic echocardiography (ECHO) is generally sufficient, unless endocarditis is suspected, in which case a transesophageal ECHO is preferred to evaluate for vegetations. If aortic root dilatation is present on ECHO, a computed tomography or magnetic resonance imaging scan may help to delineate the anatomy further. Additional laboratory testing may be warranted to further evaluate the underlying cause (e.g., serologic studies for collagen vascular disease, serologic test for syphilis, and so on).
Diagnostic assessment
With a careful examination and thorough history, the valve causing the murmur and the probable cause of the valvular lesion can be identified prior to ordering the definitive test (ECHO). The most common cause of all diastolic murmurs is still rheumatic heart disease, even though the incidence of acute rheumatic fever has decreased. Mitral stenosis is almost invariably caused by rheumatic heart disease (98% in one study of excised valves) (3,4), with the remainder caused by vegetations (from endocarditis) or congenital factors (4). Tricuspid stenosis is also predominantly rheumatic in origin and is rarely an isolated lesion. Other causes of TS include carcinoid and congenital malformations. Rheumatic heart disease is the leading cause of chronic AR, followed by congenital bicuspid valves and aortic root dilatation (Marfan’s syndrome, Ehlers-Danlos syndrome, ankylosing spondylitis, and syphilitic aortitis). If chronic, AR can result in LV dilation and compensation; if acute, it can be associated with severe LV overload and significant symptoms. Acute AR is most often related to endocarditis, aortic dissection, and trauma. Pulmonary regurgitation without hypertension has multiple causes, including pulmonary trunk dilation, endocarditis, carcinoid, trauma (from balloon-tipped catheters), and rheumatic fever. The nonstenotic physiologic murmurs are related to high-flow states across an otherwise normal mitral
or tricuspid valve. For a mitral flow murmur, the primary lesions are usually mitral regurgitation, ventricular septal defects, or patent ductus arteriosus. For a tricuspid flow murmur, an atrial septal defect or severe tricuspid regurgitation is the most common cause. The Austin–Flint murmur, caused by increasing left ventricular pressure pushing the anterior mitral leaflet into the flow of blood coming from the atrium, is the result of significant aortic regurgitation.
References
1. Chizner MA, ed. Classical teachings in clinical cardiology. Chatham, New Jersey: Laennec Publishing, 1996.
2. Coblyn JS, Weinblatt ME. Rheumatic disease and the heart. In: Braunwald E, ed. Heart disease: a textbook of cardiovascular medicine, 5th ed. Philadelphia: WB Saunders, 1997:1776–1785.
3. Abrams J, ed. Synopsis of cardiac physical diagnosis. Philadelphia: Lea & Febiger, 1989.
4. Olson LJ, Subramanian MB, Ackermann DM, Orszulak TA, Edwards WM. Surgical pathology of the mitral valve: a study of 712 cases spanning 21 years. Mayo Clin Proc 1987;62:22–34.
Pictures
Book Source Details
- Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
- Author(s): Robert B. Taylor (editor)
- Year of Publication: 2000
- Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.
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Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2008 Williams & Wilkins.
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