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Austin-flint murmur

Updated : January 1, 2024





Background

The Austin Flint murmur is a cardiac phenomenon named after the American physician Austin Flint, who first described it in the 19th century. It is a mid-diastolic, low-pitched, rumbling murmur that is heard best at the apex of the heart, and it is often associated with aortic regurgitation. 

Aortic regurgitation is a condition where the aortic valve does not close properly, allowing blood to flow back into the left ventricle during diastole. The Austin Flint murmur occurs when this regurgitant flow interferes with the normal movement of the anterior mitral valve leaflet, causing it to vibrate and produce the characteristic low-frequency murmur. 

 

Epidemiology

The Austin Flint murmur is not a separate medical condition but rather a specific auscultatory finding associated with aortic regurgitation. Therefore, when discussing its epidemiology, we are essentially talking about the prevalence and characteristics of aortic regurgitation.

Aortic regurgitation is not an extremely common condition, but its prevalence can vary depending on factors such as age, sex, and the presence of other heart conditions. Aortic regurgitation may be more prevalent in older individuals due to degenerative changes in the aortic valve with age. In some studies, aortic regurgitation has been reported to be slightly more common in men than in women. 

Anatomy

Pathophysiology

The Austin Flint murmur is associated with aortic regurgitation, and its pathophysiology is linked to the effects of regurgitant blood flow on the mitral valve. Aortic regurgitation occurs when the aortic valve fails to close properly during diastole, allowing blood to flow back (regurgitate) from the aorta into the left ventricle. This regurgitant flow increases the volume of blood in the left ventricle during diastole. During diastole, the left ventricle is supposed to fill with blood as it receives blood from both the left atrium and the regurgitant flow from the aorta.

The regurgitant blood flow creates turbulence and increases pressure in the left ventricle during diastole. The increased pressure in the left ventricle during diastole can impact the mitral valve. The anterior mitral valve leaflet, in particular, may be forced against the ventricular wall by the regurgitant flow coming from the aorta. The turbulent blood flow and the impact of regurgitant blood on the anterior mitral valve leaflet result in a vibratory motion of the mitral valve leaflet.

This vibration creates the characteristic low-pitched rumbling murmur known as the Austin Flint murmur. The murmur is best heard at the apex of the heart, where the mitral valve sounds are typically auscultated. The timing of the murmur is mid-diastolic, coinciding with the period of rapid filling of the left ventricle. The presence and intensity of the Austin Flint murmur may correlate with the severity of aortic regurgitation. More severe regurgitation may result in a more pronounced murmur. 

Etiology

Rheumatic Heart Disease: 

  • Rheumatic heart disease, caused by an autoimmune response to untreated streptococcal infections (such as strep throat), can lead to damage to the heart valves, including the aortic valve. 

Congenital Valve Abnormalities: 

  • Congenital conditions, such as bicuspid aortic valve, are associated with an increased risk of aortic regurgitation. 

Connective Tissue Disorders: 

  • Conditions affecting connective tissue, such as Marfan syndrome and Ehlers-Danlos syndrome, can contribute to the development of aortic regurgitation. 

Syphilis: 

  • In its tertiary stage, syphilis can affect the aorta, leading to aortic regurgitation. 

 

Genetics

Prognostic Factors

The prognosis for individuals diagnosed with severe aortic regurgitation accompanied by the Austin Flint murmur is contingent upon various factors. Within a decade of identifying severe aortic regurgitation, 75% of patients are expected to either succumb to the condition or necessitate valve replacement. Survival predictors encompass age, functional class, existing comorbidities, the presence of atrial fibrillation, and the correction of left ventricular end-systolic diameter for body surface area.

Those with markedly impaired left ventricular function exhibit a survival rate of 62%, in contrast to the 96% survival rate observed in patients with preserved left ventricular function. The prognosis for individuals diagnosed with severe aortic regurgitation accompanied by the Austin Flint murmur is contingent upon various factors.

Within a decade of identifying severe aortic regurgitation, 75% of patients are expected to either succumb to the condition or necessitate valve replacement. Survival predictors encompass age, functional class, existing comorbidities, the presence of atrial fibrillation, and the correction of left ventricular end-systolic diameter for body surface area. Those with markedly impaired left ventricular function exhibit a survival rate of 62%, in contrast to the 96% survival rate observed in patients with preserved left ventricular function. 

Clinical History

The Austin Flint murmur is a specific auscultatory finding associated with aortic regurgitation. Understanding the patient’s medical history involves identifying the cause of aortic regurgitation, such as rheumatic heart disease, congenital valve abnormalities, or aortic root dilation. The hallmark sign is the Austin Flint murmur, a mid-diastolic, low-pitched rumbling sound heard best at the apex of the heart.

This murmur is often associated with severe aortic regurgitation. In the early stages, aortic regurgitation may be asymptomatic, and the Austin Flint murmur may be the only clinical finding. As the condition progresses, symptoms may include fatigue, palpitations, and shortness of breath, especially during physical activity.

Aortic regurgitation typically has an insidious onset, developing over years or even decades. The condition tends to be chronic, and the Austin Flint murmur may become more pronounced over time as aortic regurgitation worsens. The Austin Flint murmur is continuous, persisting throughout diastole. Its duration may correlate with the severity of aortic regurgitation. 

Physical Examination

In addition to auscultation for the Austin Flint murmur, a thorough physical examination may reveal signs of heart failure, such as elevated jugular venous pressure, displaced apical impulse, and signs of volume overload. A blood pressure measurement in the patient will reveal an elevated pulse pressure attributable to the retrograde flow of blood through the aortic valve in diastole.

A perceptive clinician might detect a palpable “water hammer” pulse, also recognized as “Corrigan’s pulse.” This observation manifests as arterial distension succeeded by a rapid fall in diastolic pressure. Individuals may report a history of fainting or dizziness linked to difficulty in sustaining forward blood flow through the aortic valve, accentuated by a notable difference between systolic and diastolic pressures. Reduced exercise tolerance and the incapacity to carry out routine activities should trigger an assessment for this condition. 

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

  • Thyrotoxicosis 
  • Severe anemia 
  • Mitral stenosis 
  • Tricuspid stenosis 
  • Mitral regurgitation 
  • Pulmonic regurgitation 
  • Infective endocarditis 

 

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

The treatment approach for the Austin Flint murmur centers on managing severe aortic regurgitation, addressing symptoms, and preventing complications. Blood pressure control is paramount, utilizing afterload-reducing agents such as dihydropyridine calcium channel blockers or angiotensin-converting enzyme inhibitors/angiotensin receptor blockers.

Diuretics and beta-blockers may be employed for symptomatic relief. Anticoagulation considerations depend on individual factors, particularly in cases requiring aortic valve replacement with a mechanical valve. Regular monitoring through echocardiography and clinical assessments guides the management plan.

Lifestyle modifications, including activity limitations and heart-healthy habits, are integral components. In severe cases, aortic valve replacement, with the choice between mechanical and bioprosthetic valves tailored to the patient’s characteristics, remains the definitive intervention. The overall approach is individualized, aiming to enhance quality of life, alleviate symptoms, and optimize long-term outcomes for patients with the Austin Flint murmur. 

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

The ultimate treatment involves the replacement of the aortic valve. In younger individuals capable of handling anticoagulation, metallic prosthetic valves are favored due to their longer lifespan compared to bioprosthetic valves. For elderly patients and those with contraindications to anticoagulation, the implantation of bioprosthetic valves is recommended as they do not necessitate lifelong anticoagulation therapy like metallic valves. 

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Lifestyle Modifications

Depending on the severity of symptoms, patients may be advised to limit strenuous physical activities to reduce the workload on the heart.

Encouraging a heart-healthy lifestyle, including a balanced diet, regular exercise within recommended limits, and smoking cessation, is essential. 

Phases of Management

Blood Pressure Control 

Given the association with aortic regurgitation, controlling hypertension is essential.

Afterload-reducing agents such as dihydropyridine calcium channel blockers, angiotensin-converting enzyme inhibitors, or angiotensin receptor blockers may be employed.

Medications may be used to manage symptoms, such as diuretics for fluid retention and beta-blockers for heart rate control. 

Symptomatic Relief: 

  • Diuretics: In cases where there is evidence of volume overload or congestive heart failure, diuretics may be prescribed to reduce fluid retention and alleviate symptoms. 
  • Beta-Blockers: These medications can be used to control heart rate, particularly in individuals with symptoms related to increased heart rate or palpitations. 

 

Anticoagulation Considerations: 

  • Individualized Approach: If anticoagulation is necessary, an individualized approach is crucial. For instance, if the patient has coexisting conditions or contraindications to anticoagulation, careful consideration is needed. 
  • Mechanical Valve Considerations: In cases where aortic regurgitation is severe and requires aortic valve replacement with a mechanical valve, lifelong anticoagulation is generally recommended. 

 

Medication

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References

Austin-flint murmur

Updated : January 1, 2024




The Austin Flint murmur is a cardiac phenomenon named after the American physician Austin Flint, who first described it in the 19th century. It is a mid-diastolic, low-pitched, rumbling murmur that is heard best at the apex of the heart, and it is often associated with aortic regurgitation. 

Aortic regurgitation is a condition where the aortic valve does not close properly, allowing blood to flow back into the left ventricle during diastole. The Austin Flint murmur occurs when this regurgitant flow interferes with the normal movement of the anterior mitral valve leaflet, causing it to vibrate and produce the characteristic low-frequency murmur. 

 

The Austin Flint murmur is not a separate medical condition but rather a specific auscultatory finding associated with aortic regurgitation. Therefore, when discussing its epidemiology, we are essentially talking about the prevalence and characteristics of aortic regurgitation.

Aortic regurgitation is not an extremely common condition, but its prevalence can vary depending on factors such as age, sex, and the presence of other heart conditions. Aortic regurgitation may be more prevalent in older individuals due to degenerative changes in the aortic valve with age. In some studies, aortic regurgitation has been reported to be slightly more common in men than in women. 

The Austin Flint murmur is associated with aortic regurgitation, and its pathophysiology is linked to the effects of regurgitant blood flow on the mitral valve. Aortic regurgitation occurs when the aortic valve fails to close properly during diastole, allowing blood to flow back (regurgitate) from the aorta into the left ventricle. This regurgitant flow increases the volume of blood in the left ventricle during diastole. During diastole, the left ventricle is supposed to fill with blood as it receives blood from both the left atrium and the regurgitant flow from the aorta.

The regurgitant blood flow creates turbulence and increases pressure in the left ventricle during diastole. The increased pressure in the left ventricle during diastole can impact the mitral valve. The anterior mitral valve leaflet, in particular, may be forced against the ventricular wall by the regurgitant flow coming from the aorta. The turbulent blood flow and the impact of regurgitant blood on the anterior mitral valve leaflet result in a vibratory motion of the mitral valve leaflet.

This vibration creates the characteristic low-pitched rumbling murmur known as the Austin Flint murmur. The murmur is best heard at the apex of the heart, where the mitral valve sounds are typically auscultated. The timing of the murmur is mid-diastolic, coinciding with the period of rapid filling of the left ventricle. The presence and intensity of the Austin Flint murmur may correlate with the severity of aortic regurgitation. More severe regurgitation may result in a more pronounced murmur. 

Rheumatic Heart Disease: 

  • Rheumatic heart disease, caused by an autoimmune response to untreated streptococcal infections (such as strep throat), can lead to damage to the heart valves, including the aortic valve. 

Congenital Valve Abnormalities: 

  • Congenital conditions, such as bicuspid aortic valve, are associated with an increased risk of aortic regurgitation. 

Connective Tissue Disorders: 

  • Conditions affecting connective tissue, such as Marfan syndrome and Ehlers-Danlos syndrome, can contribute to the development of aortic regurgitation. 

Syphilis: 

  • In its tertiary stage, syphilis can affect the aorta, leading to aortic regurgitation. 

 

The prognosis for individuals diagnosed with severe aortic regurgitation accompanied by the Austin Flint murmur is contingent upon various factors. Within a decade of identifying severe aortic regurgitation, 75% of patients are expected to either succumb to the condition or necessitate valve replacement. Survival predictors encompass age, functional class, existing comorbidities, the presence of atrial fibrillation, and the correction of left ventricular end-systolic diameter for body surface area.

Those with markedly impaired left ventricular function exhibit a survival rate of 62%, in contrast to the 96% survival rate observed in patients with preserved left ventricular function. The prognosis for individuals diagnosed with severe aortic regurgitation accompanied by the Austin Flint murmur is contingent upon various factors.

Within a decade of identifying severe aortic regurgitation, 75% of patients are expected to either succumb to the condition or necessitate valve replacement. Survival predictors encompass age, functional class, existing comorbidities, the presence of atrial fibrillation, and the correction of left ventricular end-systolic diameter for body surface area. Those with markedly impaired left ventricular function exhibit a survival rate of 62%, in contrast to the 96% survival rate observed in patients with preserved left ventricular function. 

The Austin Flint murmur is a specific auscultatory finding associated with aortic regurgitation. Understanding the patient’s medical history involves identifying the cause of aortic regurgitation, such as rheumatic heart disease, congenital valve abnormalities, or aortic root dilation. The hallmark sign is the Austin Flint murmur, a mid-diastolic, low-pitched rumbling sound heard best at the apex of the heart.

This murmur is often associated with severe aortic regurgitation. In the early stages, aortic regurgitation may be asymptomatic, and the Austin Flint murmur may be the only clinical finding. As the condition progresses, symptoms may include fatigue, palpitations, and shortness of breath, especially during physical activity.

Aortic regurgitation typically has an insidious onset, developing over years or even decades. The condition tends to be chronic, and the Austin Flint murmur may become more pronounced over time as aortic regurgitation worsens. The Austin Flint murmur is continuous, persisting throughout diastole. Its duration may correlate with the severity of aortic regurgitation. 

In addition to auscultation for the Austin Flint murmur, a thorough physical examination may reveal signs of heart failure, such as elevated jugular venous pressure, displaced apical impulse, and signs of volume overload. A blood pressure measurement in the patient will reveal an elevated pulse pressure attributable to the retrograde flow of blood through the aortic valve in diastole.

A perceptive clinician might detect a palpable “water hammer” pulse, also recognized as “Corrigan’s pulse.” This observation manifests as arterial distension succeeded by a rapid fall in diastolic pressure. Individuals may report a history of fainting or dizziness linked to difficulty in sustaining forward blood flow through the aortic valve, accentuated by a notable difference between systolic and diastolic pressures. Reduced exercise tolerance and the incapacity to carry out routine activities should trigger an assessment for this condition. 

  • Thyrotoxicosis 
  • Severe anemia 
  • Mitral stenosis 
  • Tricuspid stenosis 
  • Mitral regurgitation 
  • Pulmonic regurgitation 
  • Infective endocarditis 

 

The treatment approach for the Austin Flint murmur centers on managing severe aortic regurgitation, addressing symptoms, and preventing complications. Blood pressure control is paramount, utilizing afterload-reducing agents such as dihydropyridine calcium channel blockers or angiotensin-converting enzyme inhibitors/angiotensin receptor blockers.

Diuretics and beta-blockers may be employed for symptomatic relief. Anticoagulation considerations depend on individual factors, particularly in cases requiring aortic valve replacement with a mechanical valve. Regular monitoring through echocardiography and clinical assessments guides the management plan.

Lifestyle modifications, including activity limitations and heart-healthy habits, are integral components. In severe cases, aortic valve replacement, with the choice between mechanical and bioprosthetic valves tailored to the patient’s characteristics, remains the definitive intervention. The overall approach is individualized, aiming to enhance quality of life, alleviate symptoms, and optimize long-term outcomes for patients with the Austin Flint murmur. 

The ultimate treatment involves the replacement of the aortic valve. In younger individuals capable of handling anticoagulation, metallic prosthetic valves are favored due to their longer lifespan compared to bioprosthetic valves. For elderly patients and those with contraindications to anticoagulation, the implantation of bioprosthetic valves is recommended as they do not necessitate lifelong anticoagulation therapy like metallic valves. 

Depending on the severity of symptoms, patients may be advised to limit strenuous physical activities to reduce the workload on the heart.

Encouraging a heart-healthy lifestyle, including a balanced diet, regular exercise within recommended limits, and smoking cessation, is essential. 

Blood Pressure Control 

Given the association with aortic regurgitation, controlling hypertension is essential.

Afterload-reducing agents such as dihydropyridine calcium channel blockers, angiotensin-converting enzyme inhibitors, or angiotensin receptor blockers may be employed.

Medications may be used to manage symptoms, such as diuretics for fluid retention and beta-blockers for heart rate control. 

Symptomatic Relief: 

  • Diuretics: In cases where there is evidence of volume overload or congestive heart failure, diuretics may be prescribed to reduce fluid retention and alleviate symptoms. 
  • Beta-Blockers: These medications can be used to control heart rate, particularly in individuals with symptoms related to increased heart rate or palpitations. 

 

Anticoagulation Considerations: 

  • Individualized Approach: If anticoagulation is necessary, an individualized approach is crucial. For instance, if the patient has coexisting conditions or contraindications to anticoagulation, careful consideration is needed. 
  • Mechanical Valve Considerations: In cases where aortic regurgitation is severe and requires aortic valve replacement with a mechanical valve, lifelong anticoagulation is generally recommended.