Chapter 21. Tricuspid & Pulmonic Valve Disease

Essentials of Diagnosis

Tricuspid regurgitation

• Prominent v wave in jugular venous pulse.
• Systolic murmur at left lower sternal border that increases with inspiration.
• Characteristic Doppler echocardiographic findings, including right ventricular (RV) volume overload (RV enlargement, paradoxical septal motion, and diastolic flattening of the interventricular septum), right atrial enlargement, and systolic turbulence in the right atrium.

Tricuspid stenosis

• Prominent a wave and reduced y descent in jugular venous pulse.
• Diastolic murmur at left lower sternal border that increases with inspiration.
• Characteristic Doppler echocardiographic findings, including a thickened and domed valve with restricted motion, right atrial enlargement, and increased diastolic velocity across the tricuspid valve.

General Considerations

Clinical interest in tricuspid valve disorders has increased because of several distinct but interrelated events in clinical cardiology. First, high-resolution, noninvasive imaging techniques have been developed and validated, allowing clinicians to easily assess the morphology and function of the tricuspid valve. Second, the frequency of tricuspid valve endocarditis has increased significantly, owing largely to an increasing population of injection drug users, patients with implanted cardiac devices or long-term central venous catheters, and, to a lesser extent, a growing number of immunocompromised patients. Third, several reparative percutaneous and surgical techniques with acceptable morbidity and mortality rates now exist. In addition, investigations in both animals and humans have demonstrated the influence of right-heart disease on cardiovascular performance vis-á-vis series and parallel interactions with the left ventricle.

Pathophysiology & Etiology

The tricuspid valve has three leaflets that are unequal in size (anterior > septal > posterior). The papillary muscles are not as well defined as those of the left ventricle and are subject to considerable variation in both their size and leaflet support. Like the mitral valve, the leaflets, annulus, chordae, papillary muscles, and contiguous myocardium contribute individually to normal valve function and can be altered by pathophysiologic processes (Table 21–1).

Tricuspid Regurgitation

Tricuspid regurgitation most frequently occurs with a structurally normal tricuspid valve (functional tricuspid regurgitation), which is the result of a dilated right ventricle and tricuspid annulus and papillary muscle dysfunction.

Functional tricuspid regurgitation is usually observed in patients with disease of the left heart (eg, left ventricular [LV] dysfunction, mitral valve disease), pulmonary vascular and parenchymal disease, right ventricular (RV) infarction, arrhythmogenic RV dysplasia, and congenital heart disease.

By contrast, organic tricuspid regurgitation occurs when the intrinsic structure of the valve is anatomically abnormal.

Rheumatic tricuspid regurgitation almost always coexists with mitral valve involvement and is due to associated pulmonary hypertension. Although two-thirds of patients with rheumatic mitral valve disease have pathologic evidence of tricuspid valve involvement, clinically significant tricuspid disease, which generally affects young and middle-aged women, is much less common. Rheumatic tricuspid involvement is usually mild and generally is shown clinically as pure regurgitation or mixed regurgitation and stenosis, caused by the fibrosis of the valve leaflets and chordae tendineae; contracture of the leaflets and commissural fusion produce regurgitation and stenosis, respectively.

Tricuspid valve endocarditis occurs primarily in injection drug users and patients with chronic intravascular hardware, left-to-right shunts, burns, and immunocompromised states. Infective endocarditis is more common in injecting drug users who are human immunodeficiency virus (HIV) positive than in those who are HIV negative. Infective endocarditis is typically caused by virulent pathogens that infect structurally normal valves. Staphylococcus aureus is the most common organism; the next most common pathogens are streptococci and enterococci. Pseudomonas and Candida species also predominate, and polymicrobial infections are not uncommon. Geographic location should also be considered when attempting to identify the responsible pathogens. Fungal endocarditis should be considered when vegetations are large; they occasionally cause obstruction. Abscesses may involve the annulus and septum, and chordal rupture or valve perforations may cause tricuspid regurgitation.

Carcinoid tumors are a rare cause of both tricuspid and pulmonic valve disease. The vasoactive substances (principally serotonin) produced by these tumors are believed to be causal, and patients with carcinoid valvular disease have higher serum levels of serotonin and increased urinary excretion of its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), than those without cardiac disease. Left-sided valve involvement is unusual due to inactivation of these vasoactive molecules by monoamine oxidase in the lungs, but can be seen in patients with right-to-left shunts or bronchial tumors. The valve exhibits pathognomonic plaque-like deposits of fibrous tissue (which may also deposit on the endocardium); leaflet distortion leads to regurgitation, stenosis, or both. Tricuspid regurgitation is the most common lesion and is detected by echocardiography in virtually all patients with carcinoid tricuspid valve disease. Cardiac involvement is progressive and causes significant morbidity and mortality in such patients, but early detection and surgical management may prolong survival. Long-term survival has been reported after tricuspid valve replacement, but carcinoid plaques may deposit on the bioprosthetic leaflets.

Tricuspid valve prolapse, owing to myxomatous degeneration, is seen almost exclusively in patients with mitral valve prolapse and occurs in as many as 50% of cases. Isolated involvement has been confirmed, however, by both echocardiography and necropsy. Anterior leaflet prolapse is most common, followed by septal and posterior leaflet prolapse. The associated tricuspid regurgitation is usually mild. Although tricuspid valve prolapse may be a marker of generalized connective tissue disease and a poor prognostic indicator in patients with mitral valve prolapse, its clinical significance remains undefined. Like mitral valve prolapse, the precise incidence of tricuspid valve prolapse is difficult to determine because of inconsistent clinical, echocardiographic, and angiographic definitions.

Tricuspid regurgitation is a frequent component of Ebstein anomaly of the tricuspid valve because of the apical displacement of septal and posterior tricuspid leaflets. This results in “atrialization” of a variable portion of the right ventricle and a range of abnormalities involving the anterior leaflet and atrial septum. The downward displacement of the tricuspid valve frequently causes a tricuspid regurgitant murmur (heard best in the apical area). This uncommon congenital abnormality is associated with right-to-left intra-atrial shunting, RV dysfunction, supraventricular arrhythmias, and sudden death.

Tricuspid regurgitation of at least moderate severity may complicate as many as 25% of cases of systemic lupus erythematosus; significant tricuspid regurgitation is usually due to the pulmonary hypertension produced by lupus pulmonary disease. Libman-Sacks endocarditis that involves the tricuspid valve is far less common. However, Libman-Sacks endocarditis has been associated with antiphospholipid antibodies, which has been shown to cause valvular thickening, isolated tricuspid involvement, and the development of nonbacterial vegetations. The cause of the valve disease is poorly understood, but intravalvular capillary thrombosis is believed to be a factor. Most patients present with combined tricuspid regurgitation and stenosis, and the regurgitation is typically moderate or severe. Pulmonary hypertension is usually present and contributes to the valvular dysfunction.

Although catheter-induced tricuspid regurgitation occurs in approximately 50% of cases with catheters across the valve, the regurgitation is quantitatively small, clinically unimportant, and usually disappears when the catheter is removed. Tricuspid regurgitation can occur as a late complication of successful mitral valve replacement (MVR). In one series, Doppler-detected moderate-to-severe regurgitation occurred in two-thirds of patients at a mean of over 11 years following MVR; over one-third of these patients had clinically evident tricuspid regurgitation. Other causes include blunt and penetrating trauma (rupture of papillary muscles, chordal disruption or detachment, leaflet rupture, complete valve destruction), primary or secondary cardiac tumors, orthotopic heart transplantation, and endomyocardial fibrosis.

Tricuspid Stenosis

Tricuspid stenosis is an uncommon lesion that is usually rheumatic in origin and almost exclusively accompanies mitral stenosis. Isolated rheumatic tricuspid stenosis is rare, and subvalvular disease is usually less severe in tricuspid than in mitral stenosis. Isolated carcinoid tricuspid stenosis is also rare; tricuspid regurgitation is more frequent and often occurs with pulmonic stenosis. Right atrial (RA) myxomas and obstructing metastatic tumors may produce hemodynamic changes that are indistinguishable from tricuspid stenosis. Tricuspid stenosis may be congenital and is infrequently predominant in Ebstein anomaly. Extrinsic compression of the tricuspid valve by a loculated pericardial effusion is an uncommon cause of tricuspid stenosis. Other unusual causes include systemic lupus erythematosus, Whipple disease, Fabry disease, antiphospholipid syndrome, infective endocarditis, endocardial fibroelastosis, and as a sequela to methysergide therapy. It should be noted that prosthetic tricuspid valves, like all prosthetic valves, are inherently stenotic.

Clinical Findings

Symptoms & Signs

Tricuspid valve disease can be difficult to recognize clinically. The symptoms may be overshadowed by associated illness, such as systemic lupus erythematosus, infective endocarditis, trauma, or neoplasia. The dominant presenting features may be symptoms that are usually not considered cardiac in origin: abdominal discomfort, ascites, jaundice, wasting, and inanition. In addition, patients with associated cardiovascular disease may have nonspecific symptoms (exertional dyspnea and fatigue in mitral stenosis) that obfuscate the diagnosis and deflect the suspicion of tricuspid valve disease. In patients with mitral stenosis, for example, tricuspid valve disease protects the pulmonary circulation and exertional dyspnea, pulmonary edema, and hemoptysis are less commonly reported, although a history of excessive fatigue may be elicited. Most often, however, the history is insufficient to diagnose tricuspid valve disease, and only a careful physical examination provides the necessary clues.

Physical Examination

Jugular Venous Pulse

Because the internal jugular veins lack effective valves, they should be inspected for an estimate of RA pressure (Figure 21–1 shows a normal jugular venous pulse). There are three waves (a, c, and v) and two descents, x and y (which correspond to the a and v waves, respectively). The a wave and the initial descent are produced by atrial contraction and relaxation, respectively. The x descent is interrupted by a c wave that is caused by isovolumetric contraction of the right ventricle and resultant bowing of the tricuspid valve toward the right atrium. The continuation of the x descent (sometimes called x′) is caused by the descent of the arteriovenous (AV) ring toward the apex during RV ejection. The right atrium fills and, because the tricuspid valve is closed, RA pressure rises, causing the v wave. The rapid fall in volume and pressure when the valve opens produces the y descent. Except for a small but variable delay, the jugular venous pulse and RA pressure contours are similar.

When inspecting the jugular venous pulse, the examiner should pay careful attention to the magnitude of the central venous (mean RA) pressure, the dominant wave (a or v), and changes in pulse contour with respiration. Tricuspid valve disease is typically associated with increased central venous pressure.

Tricuspid Regurgitation

The x descent of the jugular venous pulse is interrupted by an early v wave (c-v wave) with a rapid y descent (Figure 21–2). These findings are characteristically augmented during inspiration. The neck veins are distended, and the earlobes may pulsate. Because venous distention may obscure the jugular pulse contour, it is important to elevate the patient's head. RV volume overload leads to prominent pulsations over the left lower sternal border.

Tricuspid Stenosis

In tricuspid stenosis (Figure 21–3), inspection of the jugular veins reveals a dominant a wave (assuming sinus rhythm), which increases with inspiration, and a slow and shallow y descent due to resistance to early RV diastolic filling.

Cardiac Auscultation

Tricuspid Regurgitation

Tricuspid regurgitation is classically associated with a holosystolic murmur that is best heard at the right or left midsternal border, but when the right ventricle is markedly dilated, the location of the murmur may move toward the left and suggest mitral regurgitation. The auscultatory hallmark of tricuspid regurgitation is an inspiratory augmentation from increased systemic venous return and tricuspid valve flow (Figure 21–4). Under such circumstances as severe tricuspid regurgitation, markedly increased RA pressures, and RV systolic failure, the murmur may not increase with inspiration. Although usually described as holosystolic, the timing of the murmur may be early, mid, or late systolic. The murmur may be decrescendo when tricuspid regurgitation is severe and acute, and its character reflects the presence of a giant c-v wave; there may be a middiastolic flow rumble that resembles tricuspid stenosis. The murmur of tricuspid regurgitation is usually not accompanied by a thrill, and there is little radiation of the murmur. When the tricuspid valve is wide open in systole, there may be no murmur. An S3, which can vary in intensity and with inspiration, is often associated with an extremely dilated right ventricle. An S4 may also be heard if there is significant RV hypertrophy.

Tricuspid Stenosis

The tricuspid opening snap is difficult to distinguish from the mitral opening snap, and auscultatory findings may be difficult to distinguish from existing mitral stenosis. Unlike mitral stenosis, however, the diastolic rumble of tricuspid stenosis has a higher pitch, increases with inspiration, is usually loudest at the lower left sternal border, and follows the opening snap of mitral stenosis. The tricuspid stenosis murmur is often scratchy, ends before the first heart sound, and has no presystolic crescendo in patients with normal sinus rhythm. A diastolic murmur from relative tricuspid stenosis may be heard with large atrial septal defects and severe tricuspid regurgitation. In patients with normal sinus rhythm, a presystolic hepatic pulsation may be felt; this is due to reflux from atrial contraction against the stenotic valve. Both tricuspid stenosis and regurgitation can, if chronic, lead to ascites, peripheral edema, jaundice, wasting, and muscle loss. Tricuspid valve disease, which is often diagnosed or suspected at the bedside, can almost always be confirmed with echocardiography.

Diagnostic Studies

The diagnostic evaluation of suspected tricuspid valve disease includes electrocardiography (ECG), plain chest film, echocardiography, and cardiac catheterization. Limited experience with cine magnetic resonance imaging (MRI) and computed tomography (CT) suggests that, except in certain instances (such as the evaluation of carcinoid heart disease), these techniques offer no clear advantage over echocardiography.

Electrocardiography

P waves characteristic of RA enlargement with no evidence of RV hypertrophy suggest isolated tricuspid stenosis. Most often, however, the rhythm is atrial fibrillation. When pulmonary hypertension is the cause of tricuspid regurgitation, the ECG may show evidence of RV hypertrophy with right axis deviation and tall R waves in V1 to V2 and RA enlargement (Figure 21–5A). Atrial fibrillation is also common, and incomplete right bundle branch block and Q waves in V1 are occasionally seen. Preexcitation frequently accompanies Ebstein anomaly (Figure 21–5B).

Chest Radiography

In tricuspid stenosis, the chest film is characterized by cardiomegaly, with a prominent right-heart border caused by RA enlargement, and a dilated superior vena cava and azygos vein. Pulmonary vascular markings may be notably absent. The chest film in tricuspid regurgitation shows cardiomegaly from RA and RV enlargement; pleural effusions and elevated diaphragms from ascites may be seen. In general, a dilated heart in the absence of pulmonary congestion or pulmonary hypertension should suggest either tricuspid valve disease or pericardial effusion. Massive RA enlargement suggests Ebstein anomaly.

Echocardiography

Echocardiography is the most useful noninvasive diagnostic test for evaluating tricuspid valve disease. Two-dimensional and Doppler echocardiographic examinations can identify associated disease of the left ventricle and other cardiac valves (eg, mitral stenosis), show the anatomic sequelae of chronic tricuspid valve disease (eg, dilated right heart chambers), and detect structural abnormalities of the tricuspid valve (eg, a thickened tricuspid valve with decreased mobility, compression of the tricuspid annulus, or involvement by tumor or prolapsing or displaced leaflets and vegetations; Figure 21–6). Three-dimensional echocardiography can be helpful in defining the anatomy of the tricuspid valve.

Tricuspid Regurgitation

In tricuspid regurgitation, the echocardiographic findings usually show RV volume overload with a dilated right ventricle, paradoxical septal motion, and diastolic flattening of the interventricular septum. Color-flow Doppler echocardiography can visualize the tricuspid regurgitant jet. The tricuspid valve diastolic gradient can be quantified using continuous wave Doppler, and pulmonary arterial pressure can be estimated from the pulmonary artery acceleration time or the peak velocity of the tricuspid regurgitant jet. Two-dimensional echocardiography distinguishes between primary disease of the left heart and RV disease, both of which cause functional tricuspid regurgitation, and organic disease of the tricuspid valve. Contrast found in the inferior vena cava and hepatic veins following injection of agitated saline into an arm vein implies significant tricuspid regurgitation. On the other hand, a tricuspid valve annulus less than 3.4 cm in diameter during diastole virtually excludes significant tricuspid regurgitation. The temporal and spatial distribution of systolic turbulence in the right atrium, using color-flow mapping, can be a means of estimating the severity of the regurgitation. Systolic reversal of the Doppler signal in the hepatic veins indicates significant tricuspid regurgitation. Doppler techniques that quantitatively estimate effective regurgitant orifice, regurgitant volume, and regurgitant fraction have been developed and validated. It should be recognized that Doppler-detected tricuspid regurgitation occurs commonly in normal individuals. In such cases, the Doppler signal tends not to be holosystolic, and systolic turbulence occupies only a small area of the right atrium.

Tricuspid Stenosis

As shown in Figure 21–7, the stenotic tricuspid valve is thickened and domed and has restricted motion. The echocardiographic appearance alone may be misleading because many patients with two-dimensional echocardiographic findings that suggest tricuspid stenosis have normal tricuspid valve diastolic pressure gradients. Although the right atrium is usually dilated, the right ventricle is not enlarged in isolated tricuspid stenosis. The severity of the stenosis is determined with continuous wave Doppler. Accurate peak instantaneous and mean gradients across the stenotic tricuspid valve are readily calculated using the modified Bernoulli equation, which relates a pressure drop (dP) to the velocity (V) across a stenosis (dP = 4V 2). The pressure half-time method for calculating valve orifice area, used successfully for the mitral valve, has not been validated for the tricuspid valve. A tricuspid valve area less than 1.0 cm2 indicates severe tricuspid stenosis.

Cardiac Catheterization

Tricuspid Regurgitation

Opacification of the right atrium following injection of radiographic contrast into the right ventricle detects and estimates the severity of the regurgitation. Although right ventriculography requires a catheter across the tricuspid valve, there is no significant contrast leak into the right atrium under normal circumstances. Right atrial and ventricular pressures are elevated, and the RA pressure may become “ventricularized” as a result of a large c-v wave and an absent x descent (Figure 21–8A). Kussmaul sign (increased RA pressure with inspiration or the absence of a normal fall in RA pressure) may be seen when the regurgitation is severe.

Tricuspid Stenosis

In tricuspid stenosis, the mean RA pressure is increased; characteristically, the a wave is prominent and the y descent is slow. The hallmark of tricuspid stenosis is a diastolic gradient between the right atrium and right ventricle that increases with inspiration (Figure 21–8B). The gradients are frequently small; however, their detection is enhanced by recording RA and RV pressures simultaneously with two optimally damped catheters and equally sensitive transducers. Because of the low gradient, calculation of the valve area is unreliable. Injection or rapid volume infusion of atropine to increase the heart rate can increase the diastolic gradient and facilitate the diagnosis.

Treatment

Medical

Tricuspid regurgitation is usually well tolerated in the absence of pulmonary hypertension. When pulmonary arterial pressures increase, cardiac output falls, leading to symptoms of right-heart failure (edema, fatigue, dyspnea). Restriction of sodium and the use of potent loop diuretics decrease RA pressure. Medical therapy is also aimed at the cause of pulmonary hypertension. Treatment of associated systemic diseases is a critically important aspect of the therapeutic paradigm; it is, however, beyond the scope of this discussion. Symptomatic tricuspid stenosis is treated surgically.

Surgical

Surgery on the tricuspid valve may involve repair, reconstruction, excision, or replacement with a prosthetic valve. The decision to operate on the stenotic tricuspid valve is a straightforward one; the decision to operate on a regurgitant valve is more challenging. The surgeon must determine whether the regurgitation is functional or organic (ie, associated with a structurally normal or abnormal tricuspid valve), and if it is functional, the response of the pulmonary arterial pressure to the primary procedure should be anticipated. For example, repair may be unnecessary for functional tricuspid regurgitation if there is a high likelihood of a postoperative fall in pulmonary arterial pressure. In addition, repair of the functionally regurgitant tricuspid valve in patients with severe right ventricular dysfunction is unlikely to improve their status. However, the response of tricuspid regurgitation to reduced pulmonary artery pressure can be difficult to predict, and, as mentioned previously, significant tricuspid regurgitation often complicates successful MVR despite reduced pulmonary artery pressures. Given the high morbidity and mortality associated with reoperation to correct tricuspid regurgitation following MVR, the presence of any degree of preoperative tricuspid regurgitation, especially organic regurgitation, warrants consideration of concurrent tricuspid valve repair. Moreover, because “functional” tricuspid regurgitation may be due to unrecognized annular involvement and because annular dilation may be progressive, “prophylactic” tricuspid annuloplasty has been recommended when the annular diameter exceeds 21 mm/m2. Interestingly, in patients with chronic pulmonary thromboembolic disease, pulmonary thromboendarterectomy dramatically reduces functional tricuspid regurgitation without a change in tricuspid annular diameter.

The decision whether to repair or replace the tricuspid valve with a prosthesis depends on the suitability of valve repair, the associated surgical procedures, and the underlying disease. Thrombosis is a more frequent problem with tricuspid than with mitral prostheses. Thus, primary valve repair, when possible, is the preferred procedure. Repair of the stenotic tricuspid valve involves identifying and separating the fan chordae (the chords that support the leaflets in the area of the commissure), leaflet decalcification, and chordal or papillary muscle division.

Annuloplasty procedures correct dilatation of the tricuspid valve annulus. The dilatation, which is not symmetric, typically involves the annulus around the anterior and posterior leaflets (posterior more than anterior). The procedure involves sizing and selectively plicating the anterior and posterior annuli. Although the routine use of an annuloplasty ring is considered superior to nonring methods and is recommended by some groups, this position is not universally accepted.

When the tricuspid valve cannot be repaired and replacement is necessary, a bioprosthesis is often used because of the lower risk of thrombosis, although recent changes in valve design have significantly lowered the risk of thrombosis with mechanical prostheses. Bioprosthetic valves are also more prone to late failure than mechanical prostheses. If anticoagulation is necessary for other reasons, a St. Jude prosthesis is preferred by some surgeons—especially for younger patients. Also, there is a risk of complete heart block requiring permanent pacing with tricuspid valve replacement. Recent studies indicate that long-term outcomes (mortality, thrombosis, structural deterioration) for bioprosthetic and mechanical valves are similar.

The primary indications for surgery in patients with tricuspid valve endocarditis are uncontrollable infection, septic emboli, or refractory congestive heart failure. Because virulent organisms are the rule, they are not, per se, an indication for surgery. Total excision of the tricuspid valve is an attractive option in injection drug users, considering both recidivism and the threat of prosthetic valve endocarditis. As noted earlier, tricuspid regurgitation without pulmonary hypertension is well tolerated; however, 20% of these patients ultimately may require valve replacement for right-heart failure. Debridement and valve repair have been suggested as alternative procedures to valve excision.

Successful percutaneous balloon valvuloplasty has been reported for native valve tricuspid stenosis and stenotic bioprosthetic tricuspid valves, but experience is limited. There are no published studies to compare percutaneous balloon valvotomy with surgical valvuloplasty, and only limited long-term results have been published.

Prognosis

The natural history of tricuspid valve disease is a function of the associated valvular lesions and the underlying disease. Isolated lesions are rare, and their natural history is unknown.

Regardless of etiology, tricuspid regurgitation is associated with decreased survival, and mortality increases as severity of regurgitation increases. In general, the results of tricuspid valve surgery depend on the types of valve lesions, the corrective procedures, the degree and reversibility of LV and RV function, and the pulmonary vascular resistance. Residual tricuspid regurgitation usually occurs when the pulmonary vascular resistance remains elevated. Many patients have small-to-moderate tricuspid valve gradients after tricuspid valve replacement; like residual tricuspid valve leaks, these are usually not clinically important. Although most surgeons favor repair over replacement, the superiority of this approach is difficult to prove.

Essentials of Diagnosis

Pulmonic regurgitation

• Diastolic murmur at the left upper sternal border that increases with inspiration.
• Split S2 with a loud P2.
• Characteristic Doppler echocardiographic findings, including valvular abnormalities (depending on etiology), right ventricular enlargement, and diastolic turbulence in the right ventricular outflow tract.

Pulmonic stenosis

• Systolic murmur at the left second intercostal space preceded by a systolic click.
• Split S2 with a soft P2.
• Characteristic Doppler echocardiographic findings, including thickened and domed leaflets, and increased systolic velocities across the pulmonic valve.

General Considerations

The technologic advances made in the fields of noninvasive cardiac imaging, interventional cardiology, and cardiac surgery over the past few decades have had a noticeable effect on the diagnosis and management of pulmonic valve disease.

Pathophysiology & Etiology

The normal pulmonic valve is a semilunar valve with anterior, left, and right leaflets. The function and texture of the valve leaflets, as well as the size of the valve annulus, can be adversely affected in a variety of diseases.

Pulmonic Regurgitation

Trivial to mild pulmonic regurgitation occurs in almost everyone at any age, but more severe pulmonic regurgitation commonly occurs in the setting of pulmonary hypertension. The regurgitation is caused by dilatation of the pulmonic valve ring, and any cause of pulmonary hypertension can precipitate pulmonic regurgitation. Idiopathic dilation of the pulmonary trunk and Marfan syndrome also cause pulmonic regurgitation via a similar distortion of the valve ring. Infective endocarditis is unusual, but when present, often causes pulmonic regurgitation, with vegetations causing dysfunction of the leaflets themselves. Although the pulmonic valve is the least likely to be seeded in endocarditis, the rising number of injecting drug users, immunocompromised persons, and patients with subclinical pulmonic stenosis represent a growing population at risk. Pulmonic regurgitation can also occur as a consequence of surgical treatment for tetralogy of Fallot or balloon valvuloplasty of congenital pulmonic stenosis. The pulmonic regurgitation is generally mild and hemodynamically insignificant, but in rare cases, it can progress to RV dilation, necessitating pulmonic valve replacement. Rheumatic heart disease is an infrequent cause of pulmonic regurgitation, and it invariably occurs in the setting of multiple valve disease. Other rare causes of pulmonic regurgitation include chest trauma, carcinoid tumors, syphilis, and catheter-related valve dysfunction.

Pulmonic Stenosis

Pulmonic stenosis is a congenital disorder in over 95% of cases. Congenital pulmonic stenosis is usually caused by a valvular lesion, although subvalvular (infundibular hypertrophy) and supravalvular (rare intracardiac tumors, congenital rubella syndrome) lesions do occur. Valvular pulmonic stenosis is most often due to fibrosis of the valve with thickening of the leaflets. The leaflets dome into the pulmonary trunk during systole, producing a narrow central aperture. Less commonly, the valve leaflets are dysplastic and rubbery with a small valve annulus. Bicuspid pulmonic valves also occur. The pathologic distinctions made earlier do have some clinical relevance, as dysplastic valves are less responsive to balloon dilatation than dome-shaped valves. Isolated congenital pulmonic stenosis is the most commonly encountered congenital pulmonic valve disease in adulthood, and it typically causes valvular pulmonic stenosis. Tetralogy of Fallot also causes pulmonic stenosis with a bicuspid valve, and Noonan syndrome can be associated with dysplastic pulmonic stenosis. Other congenital syndromes associated with pulmonic stenosis include double-outlet right ventricle, atrioventricular canal defect, and univentricular atrioventricular connection.

The most common acquired form of pulmonic stenosis occurs with carcinoid heart disease. The proposed mechanism for carcinoid valve disease has been discussed earlier in this chapter. The whitish carcinoid plaques adhere to the valve leaflets and can cause both pulmonic stenosis and pulmonic regurgitation. Rheumatic heart disease is a rare cause of pulmonic stenosis and, when present, is generally seen with multiple valve disease. Large vegetations on an infected pulmonic valve can rarely cause pulmonic stenosis.

Clinical Findings

Symptoms & Signs

As with tricuspid disease, the symptoms of pulmonic valve disease can be subtle and overshadowed by coexisting illnesses. Patients with pulmonic regurgitation are often asymptomatic unless symptoms of pulmonary hypertension and RV failure eventuate. Patients with pulmonic stenosis are also frequently asymptomatic. Symptoms can appear gradually as the pulmonic valve pressure gradient increases and include exertional dyspnea, chest pain, and fatigue.

Physical Examination

Jugular Venous Waveform

The presence of pulmonic stenosis is suggested by a prominent jugular venous a wave in the setting of a relatively normal central venous pressure.

Cardiac Auscultation

Pulmonic Regurgitation

The pulmonic component of S2 is usually loud because most patients have pulmonary hypertension, and the second heart sound is often split due to prolonged RV emptying. RV S3 and S4 gallops are sometimes heard in the left parasternal area. In the absence of pulmonary hypertension, the murmur of pulmonic regurgitation is a low-pitched, crescendo–decrescendo diastolic murmur that is best heard near the left second or third intercostal space. The murmur is augmented during inspiration. However, in patients with significant pulmonary hypertension, the murmur assumes a different quality. The dilatation of the pulmonic valve annulus allows for a more forceful regurgitant jet, resulting in a high-pitched, decrescendo murmur that is best heard at the left parasternal border near the second or third intercostal space, otherwise known as the Graham Steell murmur.

Pulmonic Stenosis

The second heart sound is also split with pulmonic stenosis, and this splitting is proportional to the degree of stenosis. Unlike in pulmonic regurgitation, the pulmonic component of S2 is soft in pulmonic stenosis, and an S4 can frequently be appreciated over the lower left sternal border. A high-frequency systolic click can be heard near the left upper sternal border that precedes the late-peaking crescendo–decrescendo systolic murmur that typifies pulmonic stenosis. Unlike the murmur, the click becomes softer during inspiration due to enhanced late diastolic pulmonic valve opening with the increased RV filling. The murmur can be associated with a thrill, and an RV impulse is frequently palpable.

Diagnostic Studies

The diagnostic evaluation of pulmonic valve disease should include an ECG, chest film, and a transthoracic echocardiogram. Cardiac catheterization is generally unnecessary given the high degree of agreement between echocardiographic and catheterization data in pulmonic valve disease.

Electrocardiography

Pulmonic regurgitation and pulmonic stenosis can both cause ECG evidence of RV enlargement. Typical findings include right bundle branch block, right axis deviation, and RV hypertrophy. Mild or moderate pulmonic stenosis frequently presents with a normal ECG.

Chest Radiography

Nonspecific enlargement of the right ventricle and pulmonary arteries can be seen with pulmonic regurgitation. Characteristically, pulmonic stenosis is associated with dilatation of the main pulmonary artery.

Echocardiography

In pulmonic regurgitation, the pulsed Doppler technique is used to accurately detect the presence and severity of pulmonic regurgitation. In addition, the presence of pulmonary hypertension, RV hypertrophy and dilation, and coexistent valve disease can be detected. Transesophageal echocardiography has a role in the evaluation of suspected pulmonic valve endocarditis.

Echocardiography determines the nature, location, and severity of the stenosis. Pulmonary stenosis is diagnosed almost exclusively by Doppler echocardiography, and, as with pulmonic regurgitation, data regarding the status of the ventricles and other valves can also be obtained. Transesophageal studies may be useful when the location of the stenosis is unclear from the surface study.

Cardiac Catheterization

Cardiac catheterization is recommended in adolescents and young adults with congenital pulmonic stenosis for evaluation of the valvular gradient if the Doppler peak jet velocity is greater than 3 m/s and balloon valvotomy is feasible.

Magnetic Resonance Imaging (MRI)

MRI provides excellent images of the pulmonary outflow tract and valve and is especially useful for planning percutaneous bioprosthetic valve placement. It can also visualize the main pulmonary artery anatomy to assess for branch stenosis. In addition, it provides for accurate assessment of RV size and function. Finally, it can assess both stenosis and regurgitation quantitatively.

Treatment

Pulmonic regurgitation rarely requires specific treatment. Treatment of predisposing cardiac conditions, such as pulmonary hypertension, endocarditis, or left-sided valve disease, often improves the pulmonic regurgitation. As mentioned previously, certain patients may progress to right-heart failure from pulmonic regurgitation following repair of tetralogy of Fallot. These patients may require valve replacement, often with a bioprosthetic valve or pulmonary allograft.

Pulmonic stenosis has been managed with great success by balloon valvuloplasty. Treatment is based on severity of disease: balloon valvotomy is recommended if the RV–to–pulmonary artery peak-to-peak gradient is greater than 30 mm Hg at catheterization in the symptomatic patient, and greater than 40 mm Hg in the asymptomatic patient. Patients with dysplastic valves may not respond to balloon valvuloplasty and may require valve replacement with a bioprosthetic valve. Percutaneous stented pulmonary valve implantation is an alternative to surgical replacement of pulmonic stenosis and regurgitation in selected patients.

Prognosis

The prognosis of pulmonic valve disease is generally excellent. With pulmonic regurgitation, clinicians must consider the comorbidities involved (particularly pulmonary hypertension) that may influence prognosis. Patients with congenital pulmonic stenosis can expect a life expectancy comparable to that of the general population.