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Austin Flint Murmur

Editor: Roman Zeltser Updated: 3/13/2023 3:51:11 PM


American physician Austin Flint first described his namesake murmur in 1862.[1] In his own poetic words: "The murmur is oftener rough than soft. The roughness is often peculiar. It is a blubbering sound, resembling that produced by throwing the lips or the tongue into vibration with the breath of respiration." The murmur is best described in modern terms as a low-pitched mid to late diastolic rumble heard best at the apex of the heart and is associated with severe aortic regurgitation.


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As others had previously suggested, an echocardiogram-based study found the Austin Flint murmur was not associated with rapid mitral inflow.[2] The authors concluded that the murmur resulted from the regurgitant aortic jet alone.[2] Another study of echocardiogram findings found that the auscultated sound resulted from the abutment of the aortic regurgitant jet against the left ventricular epicardium.[3] A prior study had suggested that the Austin Flint murmur arose from a regurgitant aortic jet directed at the anterior mitral leaflet resulting in shuddering of the leaflet.[4] The authors hypothesized that this shuddering resulted in vibrations and shock waves that ultimately distorted the regurgitant aortic jet and caused the familiar sound heard in the Austin Flint murmur. Ultimately, there is no consensus about the cause of the sound auscultated as the Austin Flint murmur.


One would expect the prevalence of the Austin Flint murmur to correlate with that of severe aortic regurgitation. In the Framingham study, the incidence of moderate to severe aortic regurgitation was less than 1% in age groups under 70 years old.[5] In the 70 to 83-year-old age group, the incidence was 2.2% for men and 2.3% for women.[5] However, not all patients with severe aortic regurgitation will have an Austin Flint murmur; therefore, the true prevalence of the murmur is currently unknown.


In developing countries, the most common cause of aortic regurgitation remains rheumatic heart disease.[6] In developed countries, aortic regurgitation occurs most often in young patients with a bicuspid aortic valve and in patients with advanced age when the burden of calcific aortic disease is highest.[5]

History and Physical

The Austin Flint murmur is a rumbling diastolic murmur best heard at the apex of the heart that is associated with severe aortic regurgitation and is usually heard best in the fifth intercostal space at the midclavicular line. Younger patients are more likely to have a history of a bicuspid aortic valve or rheumatic heart disease, while older patients are more likely to suffer from calcific valvular disease. A blood pressure reading on the patient will show an increased pulse pressure due to the backflow of blood through the aortic valve during diastole. An astute clinician may be able to palpate a "water hammer" pulse, which is also known as "Corrigan's pulse." This finding demonstrates arterial swelling followed by a brisk diastolic fall. Patients may endorse a history of syncope or lightheadedness associated with an inability to maintain forward flow through the aortic valve and the significant difference between systolic and diastolic pressure. Decreasing exercise tolerance and the inability to perform activities of daily living should prompt screening for this condition. 


The most appropriate test to order in a patient with an Austin Flint murmur is a transthoracic Doppler echocardiogram.[7] A cardiac magnetic resonance imaging (MRI) scan is indicated if the echocardiogram images are suboptimal due to body habitus.[7] In severe asymptomatic aortic regurgitation, the American College of Cardiology (ACC) and the American Heart Association (AHA) recommend yearly monitoring with a transthoracic echocardiogram.[7] This monitoring interval should be shortened in patients that develop left ventricular (LV) dilation despite being asymptomatic.

Treatment / Management

Treatment and management of a patient with an Austin Flint murmur are the same as other patients with severe aortic regurgitation regardless of whether an Austin Flint murmur is present. Medical management consists of treating hypertension with afterload reducing agents such as dihydropyridine calcium channel blockers or angiotensin-converting enzyme inhibitors/angiotensin receptor blockers.[7] Definitive management is with aortic valve replacement.[7] Metallic prosthetic valves are a preferred choice in younger patients who can tolerate anticoagulation due to increased longevity compared to bioprosthetic valves.[7] Elderly patients and patients with contraindications to anticoagulation should undergo implantation of bioprosthetic valves, which do not require the same lifelong anticoagulation therapy as a metallic valve.[7] Patients who are poor surgical candidates, as determined by the Society of Thoracic Surgeons' cardiac risk score (STS score), can be evaluated for the implantation of a transcatheter aortic valve replacement.[7](A1)

Differential Diagnosis

The differential diagnosis for patients presenting with a cardiac murmur and a widened pulse pressure includes conditions associated with hyperdynamic circulation. These include: 

  • Thyrotoxicosis
  • Severe anemia
  • Wet beriberi or Thiamine deficiency
  • Presence of arteriovenous fistulae 
  • Pregnancy

Other intracardiac causes of similar physical presentation include:

  • Infective endocarditis
  • Mitral stenosis
  • Tricuspid stenosis
  • Mitral regurgitation
  • Pulmonic regurgitation

As originally described by Flint in 1862, the murmur was "presystolic in timing and indistinguishable from that of mitral stenosis."[1] The Austin Flint murmur can be differentiated from organic mitral stenosis by the presence of an opening snap in mitral stenosis. Further differentiation is achievable with amyl nitrate inhalation, which will decrease the intensity of the Austin Flint murmur due to a decrease in afterload. The murmur of mitral stenosis will increase in both duration and intensity with amyl nitrate inhalation.


The prognosis of patients with severe aortic regurgitation associated with the Austin Flint murmur depends on a variety of factors. Within ten years of diagnosis of severe aortic regurgitation, 75% of patients will either pass away or require valve replacement.[8] Predictors of survival include: age, functional class, comorbidities, atrial fibrillation, and left ventricular end-systolic diameter corrected for body surface area.[8] Those with severe left ventricular dysfunction have a survival rate of 62% compared to 96% in patients with preserved left ventricular function.[9]


Complications of severe chronic aortic regurgitation include progressive LV dysfunction and dilation that can lead to progressive, symptomatic congestive heart failure, myocardial infarction, arrhythmias, and sudden cardiac death. The presence of symptomatic aortic regurgitation portends a higher risk of complications, as well as the presence of echocardiographic findings of reduced LV ejection fraction and worsening LV end-systolic dimension. This highlights the importance of monitoring patients with aortic regurgitation to prevent adverse outcomes.


The first consultation for a patient with an Austin Flint murmur should be with a cardiologist. The cardiologist can medically manage the patient while they coordinate care with prompt referral to a cardiothoracic surgeon for evaluation of surgical aortic valve replacement. If the patient is not a candidate for a surgical aortic valve replacement due to an elevated STS score, an interventional cardiologist trained in structural heart disease should provide a consult to evaluate the patient for a transcatheter aortic valve replacement.

Deterrence and Patient Education

Patient education is key in ensuring adequate clinical outcomes for this disease. Patient education on medical compliance, including compliance with medications as well as routine monitoring, can help delay LV dysfunction and optimize the timing of surgery. Patients should be encouraged to follow up regularly with a cardiologist for routine echocardiography to improve long-term outcomes.  

Enhancing Healthcare Team Outcomes

The auscultation of an Austin Flint murmur correlates with severe aortic regurgitation. Coordinated care between the cardiologist, cardiothoracic surgeon, and an interventional cardiologist is an integral part of managing these complex patients. In patients that are candidates for replacement, surgical aortic valve replacement is the gold standard of care.[Level 1] In patients with prohibitively high STS scores, the surgeon should discuss the option for a transcatheter aortic valve approach with the patient.[Level 1] In patients that are not candidates for replacement, long-term monitoring, as well as patient education on symptom management, can help delay the need for surgery. Specialty-trained nurses in cardiology can help educate the patient on adequate medical management of symptoms, daily weight measurements, medication compliance, and compliance with routine testing to ensure patients receive optimal care. Asymptomatic patients with this disease should be screened for changes in exercise capacity and symptoms regularly. Specialty nurses can help obtain this data from patients at regularly scheduled intervals and notify the clinicians if symptoms develop. This will help optimize the timing of surgery and prevent complications. 

The recovery time from an aortic valve replacement is 4 to 8 weeks.  The most important factors in recovery are nutrition and exercise. Nutritional guidance should be provided before discharge, and follow-up with a nutritionist after discharge may be beneficial in high-risk patients. When anticoagulation is appropriate, a board-certified cardiology specialty pharmacist should also provide input. Patients that are elderly or with significant comorbidities benefit from cardiac rehabilitation, which has shown to increase aerobic capacity and quality of life.[10] [Level 1]



Flint A. Classics in cardiology: on cardiac murmurs(*) (part 3). Heart views : the official journal of the Gulf Heart Association. 2012 Apr:13(2):77-83. doi: 10.4103/1995-705X.99236. Epub     [PubMed PMID: 22919455]


Emi S, Fukuda N, Oki T, Iuchi A, Tabata T, Kiyoshige K, Fujimoto T, Manabe K, Ito S. Genesis of the Austin Flint murmur: relation to mitral inflow and aortic regurgitant flow dynamics. Journal of the American College of Cardiology. 1993 May:21(6):1399-405     [PubMed PMID: 8473648]


Landzberg JS, Pflugfelder PW, Cassidy MM, Schiller NB, Higgins CB, Cheitlin MD. Etiology of the Austin Flint murmur. Journal of the American College of Cardiology. 1992 Aug:20(2):408-13     [PubMed PMID: 1634679]


Rahko PS. Doppler and echocardiographic characteristics of patients having an Austin Flint murmur. Circulation. 1991 Jun:83(6):1940-50     [PubMed PMID: 2040046]


Singh JP, Evans JC, Levy D, Larson MG, Freed LA, Fuller DL, Lehman B, Benjamin EJ. Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Heart Study). The American journal of cardiology. 1999 Mar 15:83(6):897-902     [PubMed PMID: 10190406]


Bekeredjian R, Grayburn PA. Valvular heart disease: aortic regurgitation. Circulation. 2005 Jul 5:112(1):125-34     [PubMed PMID: 15998697]


Nishimura RA, Otto CM, Bonow RO, Carabello BA, Erwin JP 3rd, Guyton RA, O'Gara PT, Ruiz CE, Skubas NJ, Sorajja P, Sundt TM 3rd, Thomas JD, American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Journal of the American College of Cardiology. 2014 Jun 10:63(22):2438-88. doi: 10.1016/j.jacc.2014.02.537. Epub 2014 Mar 3     [PubMed PMID: 24603192]

Level 1 (high-level) evidence


Dujardin KS, Enriquez-Sarano M, Schaff HV, Bailey KR, Seward JB, Tajik AJ. Mortality and morbidity of aortic regurgitation in clinical practice. A long-term follow-up study. Circulation. 1999 Apr 13:99(14):1851-7     [PubMed PMID: 10199882]


Bonow RO, Picone AL, McIntosh CL, Jones M, Rosing DR, Maron BJ, Lakatos E, Clark RE, Epstein SE. Survival and functional results after valve replacement for aortic regurgitation from 1976 to 1983: impact of preoperative left ventricular function. Circulation. 1985 Dec:72(6):1244-56     [PubMed PMID: 4064269]


Savage PD, Rengo JL, Menzies KE, Ades PA. Cardiac Rehabilitation After Heart Valve Surgery: COMPARISON WITH CORONARY ARTERY BYPASS GRAFT PATIENTS. Journal of cardiopulmonary rehabilitation and prevention. 2015 Jul-Aug:35(4):231-7. doi: 10.1097/HCR.0000000000000104. Epub     [PubMed PMID: 25622220]

Level 2 (mid-level) evidence