Chronic Aortic Valve Regurgitation Case File

Chronic Aortic Valve Regurgitation Case File

Eugene C. Toy, Md, Michael d . Faulx, Md

Case 7

A 55-year-old man presents to the primary care clinic to establish care. He states that he is healthy and takes no medications. He is an accountant and has not seen a doctor in years. His wife urged him to make this appointment because he is no longer able to go on morning jogs with her because of fatigue. He used to exercise regularly, but he has noticed reduced endurance over the last year that he has attributed to aging. Over the past few months he has noticed shortness of breath when he walks two flights of stairs. He has also had trouble sleeping and is now requiring three pillows to stay comfortable at night. Review of systems is other wise negative. Vital signs are notable for a heart rate of 85 bpm and a blood pressure of 140/60 mmHg while sitting. He is comfortable and able to move around the examination room without difficulty. Palpation of the carotid arteries reveals a "water hammer" pulse. His apical impulse is hyperdynamic and displaced laterally. Auscultation reveals a soft S1 and an S3. An early. diastolic decrescendo murmur is heard at the left upper sternal border with the patient leaning forward. Pulmonary and abdominal examinations are normal. Extremity exam is notable for mild pitting edema up to the midshin bilaterally.

c What is the most likely diagnosis?

c What is the best next step in diagnosis?

c What is the best next step in therapy?

Answer to Case 7:

Chronic Aortic Valve Regurgitation

Summary: A previously healthy 55-year-old man presents to the primary care clinic with mild but progressive exertional dyspnea and exercise intolerance. He also describes recent-onset orthopnea. His physical examination is remarkable for “water hammer” peripheral pulses and a hyperdynamic, laterally displaced apical impulse. Auscultation reveals a soft S1 and an S3 with an early, diastolic decrescendo murmur that is heard at the left upper sternal border. Extremity exam is notable for mild pitting edema up to the midshin bilaterally.

• Most likely diagnosis: Chronic aortic regurgitation.
• Next step in diagnosis: Electrocardiogram and echocardiography.
• Next step in therapy: Surgical evaluation if the regurgitation is severe.

ANALYSIS

Objectives

1. Understand why chronic left-sided valvular regurgitation can remain asymptomatic for years.
2. Understand how to recognize chronic left-sided valvular regurgitation on physical examination.
3. Understand the diagnostic approach for chronic left-sided valvular regurgitation.
4. Understand the role of surgery in patients with chronic left-sided valvular regurgitation.

Approach To:

Chronic Aortic Valve Regurgitation

DEFINITIONS

VALVULAR REGURGITATION: Backflow of blood through the chambers of the heart due to defective closure of the valves.

MITRAL VALVE PROLAPSE: Displacement of any part of the mitral valve leaflet or their coaptation point greater than 2 mm into the left atrium during systole.

ECCENTRIC HYPERTROPHY: Thickening of the wall of a hollow organ with dilatation of its cavity.

LEFT VENTRICULOGRAPHY: Radiographic visualization of the left ventricle after the injection of a radiopaque substance.

AORTOGRAPHY: Radiographic visualization of the aorta after the injection of a radiopaque substance.

ANNULOPLASTY: Surgical reconstruction of an incompetent heart valve.

CLINICAL APPROACH

Etiology

Chronic left-sided valvular regurgitation may be asymptomatic for years, but during that period the regurgitation can result in irreversible left ventricular (LV) systolic dysfunction. Therefore, knowing how to recognize these conditions is crucial. In the normal heart, oxygenated blood returns from the lungs to the left atrium via the pulmonary veins. Blood then flows across the mitral valve into the LV before leaving the heart through the aortic valve during systole. Understanding the etiology and mechanism of left-sided valvular dysfunction is important for the appropriate management of these conditions.

Chronic mitral regurgitation (MR) results from abnormalities in any component of the mitral valve apparatus: the anterior and posterior leaflets, the mitral annulus, the chordae tendinae, and the papillary muscles. Myxomatous degeneration, endocarditis, and ischemia are some of the leading causes of mitral valve dysfunction, but there are other causes, as listed in Table 7-1. Mitral valve prolapse is another condition that has the potential to cause MR. Chronic aortic regurgitation (AR) results from abnormalities in the valve leaflets or in the aortic root. Bicuspid aortic valves, rheumatic heart disease, and endocarditis are the leading causes of leaflet dysfunction. Longstanding hypertension is a leading cause of aortic root disease. Other causes of chronic AR are listed in Table 7-1.

Abbreviations: HOCM, hypertrophic obstructive cardiomyopathy ; SAM, systolic anterior motion.

Pathophysiology

Both forms of chronic left-sided valvular regurgitation subject the LV to increased end diastolic volume. Chronic volume overload of the ventricle causes increased wall stress that stimulates ventricular myocytes to remodel, resulting in eccentric hypertrophy. Ventricular dilatation allows the heart to maintain forward cardiac output without a substantial increase in diastolic pressure. The LV can remain in this compensated albeit disadvantaged state for many years, but over time continued ventricular enlargement and interstitial fibrosis eventually leads to systolic and diastolic dysfunction. Left atrial enlargement is commonly seen in both conditions, but patients with chronic MR are much more likely to be affected by atrial enlargement due to the greater degree of left atrial volume overload. In patients with chronic MR, atrial fibrillation is a particular concern given the high likelihood for left atrial enlargement.

Clinical Presentation

When LV dysfunction develops, patients typically present with symptoms of congestive heart failure. Because treatment before the onset of LV dysfunction is ideal, physical examination and serial monitoring of left ventricular size and function are particularly important in the long-term management of these conditions. Carotid upstrokes are usually brisk. The apical impulse is hyperdynamic and laterally displaced, and a thrill may be present. Auscultation reveals a soft S1 and a widely split S2 due to early closure of the aortic valve secondary to reduced transaortic flow in systole. An S3 can sometimes be heard as well. A high-pitched, blowing, holosystolic murmur can usually be heard best at the apex and radiates to the axilla. Anteriorly directed jets can be heard at the sternum, and posteriorly directed jets can be heard at the spine. The intensity of the murmur does not increase with inspiration as with tricuspid regurgitation but can increase with handgrip. If the mechanism of the MR is due to mitral valve prolapse or papillary muscle dysfunction, the murmur may not be holosystolic, and a midsystolic click may be present.

In patients with chronic AR, a wide pulse pressure is typically present and leads to many of the classic signs that are described in Figure 7-1. Peripheral arterial examination can reveal a bisferious, or “twice-beating,” pulse. The apical impulse is usually hyperdynamic and laterally displaced. Auscultation can reveal a soft S1 due to early closure of the mitral valve. An S3 and S4 are often heard. An early diastolic, decrescendo murmur can typically be heard at the left upper sternal border, especially with the patient leaning forward. The severity of aortic regurgitation typically correlates with the duration of the murmur and not the intensity. A rumbling diastolic murmur, known as the Austin Flint murmur, can sometimes be heard at the apex. This murmur is thought to be caused by AR jet interference with mitral inflow, but the exact mechanism is unclear.

Diagnostic Approach

Laboratory evaluation of patients with chronic left-sided valvular regurgitation is usually unrevealing. The electrocardiogram (ECG) may reveal LV hypertrophy and left atrial enlargement in both chronic MR and AR. In chronic MR, the ECG may also show atrial fibrillation. In chronic AR, the ECG may show left-axis deviation.

Figure 7-1. List of eponymous findings in severe aortic regurgitation. (Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2013. All rights reserved.)

Chest radiograph may reveal cardiomegaly in both conditions. A dilated aortic knob and root may be seen in chronic AR.

Echocardiography, both transthoracic and transesophageal, is the mainstay for diagnosis and is used to determine both the severity and the mechanism of valvular dysfunction. Additionally, echocardiography provides insight into LV function and aortic root anatomy. Cardiac catheterization in patients with chronic MR may reveal prominent V waves on pulmonary capillary wedge pressure tracings. Left ventriculography and aortography also provides information about ventricular function and the severity of valvular disease. Coronary angiography is helpful in ruling out concomitant coronary artery disease in patients requiring surgery. Cardiac magnetic resonance imaging can be helpful, particularly in chronic AR because of its ability to accurately assess the size of the LV and aortic root.

Treatment

Patients with symptomatic severe chronic left-sided valvular regurgitation should be considered for surgical treatment. In chronic MR, when primary valve dysfunction exists as in myxomatous degeneration or rheumatic heart disease, mitral valve repair or replacement is generally indicated. When the MR is secondary to LV dysfunction (termed “functional MR” as in ischemic heart disease and dilated cardiomyopathy), aggressive medical therapy of the underlying disease should be pursued first because surgical correction of the mitral regurgitation may not improve systolic function or symptoms. Differentiaion between primary and functional mitral regurgitation can sometimes pose a challenge to the managing clinician and may require the use of more advanced diagnostic imaging such as transesophageal echocardiography (TEE) or magnetic resonance imaging (MRI) to assess for left ventricular viability.

In patients with asymptomatic severe chronic valvular regurgitation, the decision on the timing of surgery is more complex. The goal with asymptomatic patients is to intervene before left ventricular remodeling becomes extreme and results in permanent dysfunction (Table 7-2). Symptoms in the setting of severe aortic or mitral valvular regurgitation, including dyspnea or exercise intolerance, provide a clear indication for surgical management of that patient. Additional factors such as the presence of atrial fibrillation or pulmonary hypertension are also considered when choosing treatment options for severe MR. Aortic valve surgery is indicated in symptomatic or asymptomatic patients with severe AR and either an LV ejection fraction of <50% or those undergoing cardiac surgery for another reason.

In patients with severe MR who require surgery, mitral valve repair is preferred over replacement because studies suggest better postoperative LV function and survival with repair. Mitral valve repair usually involves placement of an annuloplasty ring to reduce the diameter of the mitral annulus and subsequently improve closure of the valve leaflets. Mitral valve replacement is performed with either a mechanical or bioprosthetic valve, and the need for chronic anticoagulation with the mechanical valve must be weighed against the reduced longevity of the bioprosthetic valve when making this decision. The typical “life expectancy” of a bioprosthetic heart

Abbreviations: LVd d, left ventricular dimension in diastole; LVd s, left ventricular dimension in systole; LVEF, left ventricular ejection fraction. *It is also considered appropriate to pursue mitral valve repair in asymptomatic patients with severe  regurgitation and normal ventricles if there is a > 90% success rate for mitral repair at the institution where the surgery will be performed .

valve is difficult to predict and varies with valve position, valve type, and patient characteristics. Some patients with severe AR may be candidates for surgical repair such as those with bicuspid aortic valves, but most undergo replacement with either a bioprosthetic or mechanical aortic valve.

Medical therapy is indicated in patients with chronic severe valvular dysfunction if they are not operative candidates. In patients with severe MR, the objectives of medical therapy include preload reduction, blood pressure control, and maintenance of sinus rhythm. Unlike acute mitral regurgitation, the role of aggressive afterload reduction in chronic mitral regurgitation is less clear. In patients with hypertension or a separate indication for afterload reduction such as LV systolic dysfunction, the use of drugs such as ACE inhibitors or angiotensin receptor blockers is reasonable, but their use in normotensive patients with normal LV function and severe chronic MR has not been clearly shown to be beneficial. In patients with severe AR, vasodilator therapy with ACE inhibitors, hydralazine, and calcium channel blockers are generally recommended. Patients with significant aortic root dilatation are often started on beta-blockers and/or angiotensin receptor blockers, especially if they have Marfan’s syndrome. Serial echocardiography should be performed on asymptomatic patients with chronic left-sided valvular regurgitation to assess for progressive valvular dysfunction and the development of LV dysfunction or dilatation.

CASE CORRELATION

• See also Case 6 (acute valvular regurgitation).

COMPREHENSION QUESTIONS

7.1 A 70-year-old man with rheumatic heart disease complicated by severe mitral regurgitation presents to the emergency department for evaluation of fatigue. Which of the following physical examination findings is not characteristic of this disease?

A. Laterally displaced apical impulse

B. Soft S1

C. Widely split S2

D. Blowing, holosystolic murmur at the left lower sternal border that increases with inspiration

E. Brisk carotid upstrokes

7.2 A 60-year-old woman with a bicuspid aortic valve complicated by chronic aortic regurgitation is seeking a second opinion. Her most recent echocardiogram showed severe AR but normal LV function and size. Additionally, the ascending aorta was normal. She is quite active in her community and denies symptoms of congestive heart failure. She insists on being referred to a cardiac surgeon for replacement. What is the next step in therapy?

A. Reassure the patient and tell her to return only when she develops symptoms

B. Obtain serial echocardiograms to monitor for the onset of LV dysfunction or dilatation

C. Start an ACE inhibitor to slow the progression of disease

D. Refer her to a cardiac surgeon for aortic valve repair

E. Refer her to a cardiac surgeon for aortic valve replacement

7.3 A 50-year-old man with asymptomatic severe chronic MR secondary to myxomatous degeneration presents to the clinic for routine follow-up. He is an attorney and has been quite busy with work. He denies symptoms of congestive heart failure. His examination is unchanged from his prior visit. His echocardiogram today shows interval worsening of his LV ejection fraction to 45%. What is the next best step in management?

A. Repeat echocardiogram in 3 months

B. Start an ACE inhibitor

C. Refer for mitral valve repair

D. Refer for mitral valve replacement with bioprosthetic valve

E. Refer for mitral valve replacement with mechanical valve

ANSWERS

7.1 D. The murmur of MR is a blowing, holosystolic murmur that is typically heard best at the apex and does not increase with inspiration. The murmur that is described is tricuspid regurgitation.

7.2 B. In patients with asymptomatic severe AR, serial echocardiograms should be obtained to monitor for the onset of LV dysfunction or dilatation.

7.3 C. In asymptomatic patients with primary severe MR and LV dysfunction, mitral valve repair is preferred over mitral valve replacement because studies suggest better postoperative LV function and survival with repair.

CLINICAL PEARLS

C Patients with chronic left-sided valvular regurgitation may remain asymptomatic for years. making physical examination and serial echocardiography vitally important for diagnosis and management.

C In patients with chronic left-sided valvular regurgitation. remodeling of the LV in response to volume overload accounts for many of the physical examination findings.

C Echocardiography is the mainstay for diagnosis and provides information about the severity and mechanism of valvular dysfunction.

C Patients with symptomatic severe chronic left-sided valvular regurgitation should be considered for surgery.

C Mitral valve repair is preferred over mitral valve replacement because studies suggest better postoperative LV function and survival with repair.

References

Carabello BA. The current therapy for mitral regurgitation. J Am Coll Cardiol. 2008; 52:319–326. 

Carabello BA, Crawford FA. Valvular heart disease. N Engl J Med. 1997;337:32–41. 

Enriquez-Sarano M, Tajik AJ. Clinical practice. Aortic regurgitation. N Engl J Med. 2004; 351: 1539–1546. 

Fauci AS, Braunwald E. Harrison’s Principles of Internal Medicine. 17th ed. New York, NY: McGraw-Hill; 2008:1465–1480. 

Griffin BP, Callahan TD, Menon V. Manual of Cardiovascular Medicine. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:238–295. 

Sabatine MS. Pocket Medicine. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:121–123. 

Sapira JD. Quincke, de Musset, Duroziez, and Hill: some aortic regurgitations. South Med J. 1981;74: 459–467.

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