VALVULAR HEART DISEASE

VALVULAR  HEART DISEASE:

Mitral Stenosis

Definition. Most common lesion caused by rheumatic fever consisting of thickened mitral valve leaflets, fused commissures, and chordae tendineae. May result in right ventricular failure.

Etiology. Two-thirds of patients with mitral stenosis are women.

• Usually due to abnormalities of the mitral leaflets

• Most cases are secondary to rheumatic fever

• Rarely due to a congenital defect

Pathogenesis

• Mitral valve stenosis impedes left ventricular filling

• Increased left atrial pressure is referred to the lungs, causing pulmonary congestion

• Forward cardiac output becomes reduced, secondary pulmonary vasoconstriction occurs, and eventually right ventricular failure results

Clinical Symptoms. Usually manifest slowly over years.

• Dyspnea

• Orthopnea

• Paroxysmal nocturnal dyspnea

• Fatigue

• Wasting

• Hemoptysis (due to rupture of pulmonary  vessels)

• Systemic embolism (due to stagnation of blood in an enlarged left atrium)

• Hoarseness (due to impingement of an enlarged left atrium on the recurrent laryn- geal nerve)

• Right-sided heart failure

– Hepatomegaly

– Ascites

– Peripheral edema

Physical Signs

• Atrial fibrillation (irregular cardiac rhythm)

• Pulmonary rales

• Decreased pulse pressure

• Loud S1

• Opening snap following S2

• Diastolic rumble (low-pitched apical murmur)

• Sternal lift (due to right ventricular enlargement)

Diagnosis

EKG

• May show signs of right ventricular hypertrophy

• May show left and right atrial abnormalities

• Atrial fibrillation often occurs

Chest X-ray

• Large left atrium (indicated by a double-density right heart border, posterior dis- placement of esophagus, and elevated left mainstem bronchus), straightening of the left heart border

• May show signs of pulmonary hypertension, including Kerley B lines and increased vascular markings

• Large pulmonary artery

Echocardiography

•            Shows thickening of mitral valve leaflets and a reduction in the excursion and area of the valve leaflets

•            May also show left atrial enlargement

Treatment

Medical Therapy

•            Diuretics and salt-restricted diet

•            Digitalis to control the ventricular rate in patients with AF

•            Anticoagulants in patients with AF

•            Balloon valvulotomy is the standard of care for MS

Surgical Management

•            Indicated when patient remains symptomatic (functional class III) despite medical therapy

•            Mitral commissurotomy or valve replacement, if balloon dilation fails

•            Pulmonary hypertension is not a contraindication for surgery

Mitral  Regurgitation

Definition. Backflow of blood from the left ventricle into the left atrium, due to inadequate functioning (insufficiency) of the mitral valve. Most commonly from ischemia.

Etiology. Due to abnormalities of the mitral leaflets, annulus, and chordae tendinea.

•            Common causes are hypertension, CHF, ischemic heart disease, rheumatic fever, and any cause of dilation of the left ventricle

•            Occurs more commonly in men

Table 5-8. Acute versus Chronic Etiologies of Mitral Valve Regurgitation

Acute

Chronic

•            Rupture chordae tendineae (permits prolapse of a portion of a mitral valve leaflet into the left atrium) •            Papillary muscle rupture •            Endocarditis (may lead to valvular destruction) •            Trauma

•            Rheumatic heart disease (causing scarring and retraction of valve and leaflets) •            Papillary muscle dysfunction •            Mitral valve prolapse (click-murmur syndrome, Barlow syndrome, floppy mitral valve) •            Endocarditis •            Calcification of the mitral valve annulus •            Accompanying hypertrophic obstructive cardiomyopathy •            Congenital endocardial cushion defect, corrected transposition •            Endocardial fibroelastosis •            Severe left ventricular dilatation

Pathogenesis

•            A portion of the left ventricular stroke volume is pumped backward into the left atrium instead of forward into the aorta, resulting in increased left atrial pressure and decreased forward cardiac output.

•            Volume overload occurs, increasing preload.

•            Afterload is decreased as the left ventricle empties part of its contents into the rela- tively low-pressure left atrium.

•            This helps to compensate for the regurgitation by augmenting ejection fraction.

•            Left ventricular dysfunction occurs after prolonged compensation.

Clinical Manifestations

Left ventricular failure is manifested by:

•            Dyspnea

•            Orthopnea

•            Paroxysmal nocturnal dyspnea

Severe and chronic mitral regurgitation lead to right-sided failure presenting with:

•            Edema

•            Ascites

•            Anorexia

•            Fatigue

May also have pulmonary hypertension as a late finding.

Physical Signs

•            Hyperdynamic and displaced (downward and to the left) left ventricular impulse

•            Carotid upstroke diminished in volume but brisk

•            Holosystolic apical murmur radiating to the axilla and often accompanied by a  thrill

•            S3  heard with a soft S1  and widely split S2

•            Distended neck veins when severe or acute

Diagnosis

•            EKG shows signs of left ventricular hypertrophy and left atrial enlargement.

•            Chest x-ray shows cardiac enlargement, with vascular congestion when the regurgi- tation has led to heart failure.

•            Echocardiography: The mitral valve can prolapse into the left atrium during systole in cases of a ruptured chordae or mitral valve prolapse. Regardless of the cause, left atrial and left ventricular enlargement occurs if the condition is chronic.

•            Catheterization is the single most accurate test.

Treatment. With medical therapy, the goal is to relieve symptoms by increasing forward car- diac output and reducing pulmonary venous hypertension.

•            ARBs or hydralazine

•            Arteriolar vasodilators (ACE inhibitors)

•            Digitalis

•            Diuretics

 

With surgery, mitral valve replacement is used. Guidelines for selecting patients with mitral regurgitation for operation:

•            With significantly limiting symptoms and severe mitral regurgitation, surgery is usually indicated. The risk of surgery rises in chronic heart failure.

•            In patients with regurgitation who have few or no symptoms, surgery should be deferred. Their condition may remain stable for years.

•            Surgery is indicated when symptoms persist despite optimal medical management.

•            Criterion is an ejection fraction <60% or left ventricular end systolic diameter >40 mm.

•            Repair is preferable to replacement.

Mitral Valve Prolapse

Definition. The most common congenital valvular abnormality typically seen in young women and associated with connective tissue disease (e.g., Marfan or idiopathic).

Presentation. Most patients are asymptomatic. Lightheadedness, palpitations, syncope, and chest pain may occur. These symptoms are often due to arrhythmias, which may occur.

Auscultation

•            Mid-to-late systolic click and a late systolic murmur at the cardiac apex

•            Worsens with Valsalva or standing

•            Improves with squatting or leg raise

Complications (all very rare)

•            Serious arrhythmias

•            Sudden death

•            Congestive heart failure

•            Bacterial endocarditis (but does not mean routine dental prophylaxis is indicated)

•            Calcifications of valve

•            Transient cerebral ischemic attacks

Laboratory

Two-Dimensional/Doppler Echocardiography: Marked systolic displacement of mitral leaflets with coaptation point at or on the left atrial side of the annulus; moderate systolic displacement of the leaflets with at least moderate mitral regurgitation.

Treatment. No specific treatment is needed in the majority of cases. Medical Management: Beta blocker for chest pain and palpitations Surgical Management: Mitral valve replacement, rarely

 

Aortic Stenosis

Etiology

•            Calcification and degeneration of a congenitally normal valve; more common in the elderly population. This is the most common cause.

•            Calcification and fibrosis of a congenitally bicuspid aortic valve.

•            Rheumatic valvular disease: If the aortic valve is affected by the rheumatic fever, the mitral valve is also invariably affected.

Pathophysiology

Aortic stenosis results in elevation of left ventricular systolic pressure, and the resultant left ventricular hypertrophy maintains cardiac output without dilation of the ventricular cavity. Therefore, the stroke volume is normal until the late stages of the disease.

Forceful atrial contraction augments filling at the thick, noncompliant ventricle and gener- ates a prominent S4 gallop that elevates the left ventricular end-diastolic pressure.

Left ventricular hypertrophy and high intramyocardial wall tension account for the increased oxygen demands and, along with decreased diastolic coronary blood flow, account for the occurrence of angina pectoris.

As the myocardium fails, mean left ventricular diastolic pressure increases, and symptoms of pulmonary congestion ensue.

Clinical Manifestations

•            Classic symptoms are angina, syncope, and dyspnea from congestive heart failure

•            Pulsus tardus et parvus

•            Carotid thrill

•            Systolic ejection murmur in aortic area, usually with thrill, harsh quality, radiates to carotids

•            S4 gallop

•            A2 decreased, S2 single or paradoxically split

•            Aortic ejection click

Diagnosis

•            EKG will often show left ventricular hypertrophy.

•            Chest x-ray may present with calcification, cardiomegaly, and pulmonary congestion.

•            Echocardiography shows thick aortic valve leaflets with decreased excursion and LVH.

Treatment

•            Endocarditis prophylaxis is no longer recommended.

•            Surgery (valve replacement) is advised when symptoms develop, which is when the valve area is reduced below 0.8 cm2 (normal aortic orifice, 2.5–3 cm2). Generally, if patient has symptoms from stenosis, surgery is the treatment of choice.

•            Balloon valvuloplasty may be useful in those too ill to tolerate surgery.

  

Table 5-9. Differential Diagnosis of Aortic Valve Stenosis

Disease Entity	Differentiating Features
Aortic valve sclerosis of the elderly, without stenosis	•            Systolic murmur does not peak late •            Carotids do not have delayed upstrokes •            No left ventricular hypertrophy by EKG •            Echocardiographic visualization of excursion of valve leaflets usually normal or mildly reduced, but valves may not be visualized •            No hemodynamically significant aortic valve gradient by cardiac catheterization
Hypertrophic obstructive cardiomyopathy	•            Brisk bifid carotid upstrokes •            Murmur usually does not radiate into neck •            Characteristic change in murmur with various maneuvers •            Pseudoinfarct pattern (large septal Q waves) on EKG •            Characteristic echocardiographic features
Mitral regurgitation	•            Murmur is holosystolic and radiates to axilla and not carotids •            Carotid upstroke may be normal •            Dilated left ventricle •            Aortic valve normal on echocardiogram unless there is associated aortic valve disease
Pulmonic stenosis	•            Murmur does not radiate into neck; loudest along the left sternal border; increases with inspiration •            Physical examination, chest x-ray, and EKG may reveal enlarged right ventricle •            Echocardiogram reveals right ventricular enlargement and hypertrophy

Note: All of the above have a systolic murmur that can be confused with aortic stenosis.

 

Table 5-10. Effect of Various Maneuvers on Systolic Murmurs

	Valsalva	Phenylephrine Handgrip	Squatting	Amyl Nitrite	Leg Raising
Aortic stenosis	Decrease	Decrease	Increase or decrease	Increase	Increase
Hypertrophic obstructive cardiomyo- pathy	Increase	Decrease	Decrease	Increase	Decrease
Ventricular septal defect	Decrease	Increase	No change	Decrease	Increase
Mitral regurgitation	Decrease	Increase	Increase	Decrease	Increase

Aortic Regurgitation

Etiology. Systemic hypertension and ischemic heart disease are the most common causes of aortic regurgitation.

•            It may occur after infectious endocarditis.

•            Conditions that may affect the ascending aorta and cause aortic regurgitation:

–           Syphilis

–           Ankylosing spondylitis

–           Marfan syndrome

–           Rheumatic fever

–           Aortic dissection

–           Aortic trauma

Pathophysiology

Aortic regurgitation results in a volume overload of the left ventricle.

•            The ventricle compensates by increasing its end-diastolic volume according to the Frank-Starling mechanism.

•            The left ventricular dilation is thought to overstretch the myofibrils, leading to less actin–myosin interaction and decreased contractility.

•            In acute severe aortic regurgitation, the left ventricle has not had the opportunity to dilate, its compliance is relatively high, and the aortic regurgitation therefore leads to very high left ventricular end-diastolic pressure.

If mitral regurgitation ensues, the elevated left ventricular diastolic pressure is reflected back to the pulmonary vasculature, and acute pulmonary edema may occur.

Acute aortic regurgitation results in a lower cardiac output, narrower aortic pulse pressure, and a smaller left ventricle than does chronic aortic regurgitation.

 

Aortic diastolic pressure decreases in chronic aortic regurgitation because of both the regur- gitation of blood into the left ventricle and a compensatory decrease in systemic vascular resistance to maintain forward cardiac flow to the periphery. The increased pulse pressure in chronic aortic regurgitation is due to the large stroke volume, causing increased systolic and decreased diastolic pressure.

Clinical Manifestations

•            Dyspnea is the most common complaint.

•            Diastolic decrescendo murmur is the most typical.

•            Systolic flow murmur

•            Duroziez sign: Systolic and/or diastolic thrill or murmur heard over the femoral arteries

•            S3 in early left ventricular decompensation

•            Austin-Flint murmur

•            Remember: Aortic regurgitation can cause 3 different murmurs.

Diagnosis

•            EKG: LV hypertrophy often with volume overload pattern (narrow deep Q waves in left precordial leads)

•            Chest x-ray: LV and aortic dilation

•            Echocardiography: Dilated LV and aorta; left ventricular volume overload; fluttering of anterior mitral valve  leaflet

Treatment. Endocarditis prophylaxis is no longer recommended.

•            Salt restriction, diuretics, after load reduction (e.g., ACE inhibitors)

•            Aortic valve replacement when symptoms worsen or ejection fraction decreases.

•            Vasodilators such as an ACE, ARB, or nifedipine are the standard of care.

•            Perform surgery when the ejection fraction is <55% or left ventricular systolic diameter is >55 mm.