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Tricuspid, Pulmonic, and Multivalvular Disease
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Tricuspid Stenosis
Causes and Pathology
Tricuspid stenosis (TS) is almost always rheumatic in origin, although rheumatic valve disease more commonly affects left-sided valves. Other causes of obstruction to right atrial emptying are unusual and include congenital tricuspid atresia (see Chapter 82 ); right atrial tumors, which may produce a clinical picture suggesting rapidly progressive TS; and device leads, which more often are associated with tricuspid regurgitation (TR) but can become looped and fused to the tricuspid valve apparatus, and if multiple could cause obstruction. The carcinoid syndrome (see Chapter 52 ) and use of ergot-related drugs more frequently produce TR, which if severe, contributes to a gradient across the tricuspid valve ( 
). Dysfunction, including thrombosis, of a tricuspid mechanical or bioprosthetic valve can result in stenosis. Rarely, endomyocardial fibrosis, tricuspid valve vegetations, or extracardiac tumors cause obstruction to right ventricular (RV) inflow. Localized compression of the right atrium by a pericardial effusion may also lead to RV inflow obstruction and may be unrecognized if the effusion is mistaken for the right atrium ( Fig. 77.1 and ).
Most patients with rheumatic tricuspid valve disease have TR or a combination of TS and TR. Isolated rheumatic tricuspid valve disease is uncommon, and this lesion generally accompanies mitral valve disease, which dominates the presentation (see Chapter 75, Chapter 76 ). In many patients with TS, the aortic valve also is involved (i.e., trivalvular stenosis is present). TS is found at autopsy in approximately 15% of patients with rheumatic heart disease but is of clinical significance in only approximately 5%. Organic tricuspid valve disease is more common in India, Pakistan, and other developing nations near the equator than in North America or Western Europe. The anatomic changes of rheumatic TS resemble those of mitral stenosis (MS), with fusion and shortening of the chordae tendineae and fusion of the leaflets at their edges, producing a diaphragm with a fixed central aperture, typically without calcification. Like MS, TS is more common in women. The right atrium often is greatly dilated in TS, and its walls are thickened. There may be evidence of severe passive congestion, with enlargement of the liver and spleen, and right atrial thrombus formation which may extend into the vena cava or cause pulmonary embolism.
Pathophysiology
A diastolic pressure gradient between the right atrium and ventricle—the hemodynamic expression of TS—is augmented when the transvalvular blood flow increases during inspiration or exercise and is reduced when the blood flow declines during expiration. A relatively modest diastolic pressure gradient (i.e., a mean gradient of only 5 mmHg) usually is sufficient to elevate the mean right atrial pressure to levels that result in systemic venous congestion and, unless sodium intake has been restricted or diuretics have been given, is associated ultimately with jugular venous distention, ascites, and edema.
In patients with sinus rhythm, the right atrial a wave may be very tall. Resting cardiac output usually is markedly reduced and fails to rise during exercise. This accounts for the normal or only slightly elevated left atrial, pulmonary arterial, and RV systolic pressures, despite the frequent presence of accompanying mitral valvular disease.
A mean diastolic pressure gradient across the tricuspid valve as low as 2 mmHg and the typical echocardiographic appearance of leaflet restriction or doming is sufficient to establish the diagnosis of TS. Exercise, deep inspiration, and the rapid infusion of fluids or the administration of atropine may greatly enhance a borderline pressure gradient in a patient with TS. The diagnosis is generally made with transthoracic echocardiography; occasionally, transesophageal echocardiography (TEE) or other imaging such as cardiac magnetic resonance imaging (CMR) or computed tomography (CT) is necessary. Invasive assessment is rarely necessary.
Clinical Presentation
Symptoms
The low cardiac output in TS causes fatigue, and patients often experience discomfort from hepatomegaly, ascites, and anasarca (see Table 77.1 ). The severity of these symptoms, which are secondary to an elevated systemic venous pressure, is out of proportion to the degree of dyspnea. Some patients complain of a fluttering discomfort in the neck, caused by giant a waves in the jugular venous pulse. Occasionally, the symptoms of MS (severe dyspnea, orthopnea, and paroxysmal nocturnal dyspnea) may be masked by severe TS because the latter prevents surges of blood into the pulmonary circulation behind the stenotic mitral valve. The absence of symptoms of pulmonary congestion in a patient with obvious MS should suggest the possibility of TS.
TABLE 77.1
Clinical and Laboratory Features of Rheumatic Tricuspid Stenosis
Modified from Ockene IS. Tricuspid valve disease. In Dalen JE, Alpert JS, eds. Valvular Heart Disease . 2nd ed. Boston: Little, Brown; 1987:356, 390.
| History |
|
| Physical Findings |
|
| Imaging Findings |
|
Physical Examination (see Chapter 13 )
Because of the high frequency with which MS occurs in patients with TS, the similarity in the physical findings between the two valvular lesions, and the subtlety of physical findings in TS, echocardiography is essential to diagnose TS. The physical findings of TS may be attributed to MS, which is more common and associated with a louder murmur. Therefore a high index of clinical suspicion is required to detect TS. In the presence of sinus rhythm, the a wave in the jugular venous pulse is tall, and a presystolic hepatic pulsation often is palpable. The y descent is slow and barely appreciable. The lung fields are clear and, despite engorged neck veins and the presence of ascites and anasarca, the patient may be comfortable while lying flat. Thus, the diagnosis of TS may be suspected from inspection of the jugular venous pulse in a patient with MS but without clinical evidence of pulmonary hypertension. This suspicion is strengthened when a diastolic thrill is palpable at the lower left sternal border, particularly if the thrill appears or becomes more prominent during inspiration.
The auscultatory findings of the accompanying MS usually are prominent and often overshadow the more subtle signs of TS. A tricuspid opening snap (OS) may be audible but often is difficult to distinguish from a mitral OS. However, the tricuspid OS usually follows the mitral OS and is localized to the lower left sternal border, whereas the mitral OS usually is most prominent at the apex and radiates more widely. The diastolic murmur of TS is also commonly heard best along the lower left parasternal border in the fourth intercostal space and usually is softer, higher-pitched, and shorter in duration than the murmur of MS. The presystolic component of the TS murmur has a scratchy quality and a crescendo-decrescendo configuration that diminishes before S 1 . The diastolic murmur and OS of TS both are augmented by maneuvers that increase trans-tricuspid valve flow, including inspiration, the Mueller maneuver (forced inspiration against a closed glottis), assumption of the right lateral decubitus position, leg raising, inhalation of amyl nitrite, squatting, and isotonic exercise. They are reduced during expiration or the strain of the Valsalva maneuver and return to control levels immediately (i.e., within two or three beats) after the Valsalva release.
Echocardiography
The tricuspid valve should be carefully inspected at the time of echocardiography in any patient with known or suspected rheumatic heart disease or other valve disease known to affect multiple valves. The echocardiographic changes (see Chapter 16 ) of the tricuspid valve in rheumatic TS resemble those observed in the mitral valve in rheumatic MS (see Fig. 16.47). Two-dimensional echocardiography characteristically shows diastolic doming of the leaflets ( 
), thickening and restricted motion of the other leaflets, reduced separation of the tips of the leaflets, and a reduction in diameter of the tricuspid orifice. The presence of commissural fusion and the anatomy of the valve and subvalvular apparatus should also be assessed, as these features may impact therapy. TEE allows added delineation of the details of valve structure. Doppler echocardiography can be helpful in assessment of the tricuspid valve even when 2-dimensional images are suboptimal. In TS, Doppler shows a prolonged slope of antegrade flow and compares well with cardiac catheterization in the quantification of TS and assessment of associated TR. Doppler evaluation of TS has largely replaced the need for catheterization to assess severity. Severe TS is characterized by a valve area of ≤1cm 2 as assessed by the continuity equation. The pressure half-time is generally greater than 190 msec, and the right atrium and inferior vena cava are dilated. The mean pressure gradient across the tricuspid valve varies with heart rate, but a mean gradient ≥5 mm Hg is consistent with significant TS. Additional assessment of valve morphology may be provided by three-dimensional echocardiography, which allows en face views of the tricuspid valve from the atrial and ventricular aspects with simultaneous views of all three leaflets ( ).
Other Diagnostic Evaluation Modalities
Electrocardiography
In the absence of atrial fibrillation (AF) in a patient with valvular heart disease, TS is suggested by the presence of electrocardiographic evidence of right atrial enlargement (see Chapter 14 ). The P wave amplitude in leads II and V 1 exceeds 0.25 mV. Because most patients with TS have mitral valve disease, the electrocardiographic signs of biatrial enlargement commonly are seen. The amplitude of the QRS complex in lead V 1 may be reduced by the dilated right atrium.
Radiography
The key radiologic finding is marked cardiomegaly with conspicuous enlargement of the right atrium (i.e., prominence of the right heart border), which extends into a dilated superior vena cava and azygos vein, but without conspicuous dilation of the pulmonary artery. The vascular changes in the lungs characteristic of mitral valvular disease may be masked, with little or no interstitial edema or vascular redistribution, but left atrial enlargement may be present.
The stenotic tricuspid valve can also be visualized with CMR or computed tomographic imaging and right atrial and ventricular volumes quantified.
Cardiac Catheterization
Invasive hemodynamic assessment of TS is rarely needed but is appropriate in the symptomatic patient in whom the physical findings and noninvasive data are discordant. It may occasionally be undertaken in patients undergoing invasive hemodynamic assessment for another indication. Right atrial and RV pressures can be recorded simultaneously, using two catheters or a single catheter with a double lumen, with one lumen opening on either side of the tricuspid valve.
Management
Although the fundamental approach to the management of severe TS is surgical treatment, intensive sodium restriction and diuretic therapy may diminish those symptoms secondary to the accumulation of excess salt and water. If AF is present, ventricular rate control is needed to improve diastolic filling. A preparatory period of diuresis may diminish hepatic congestion, thereby improving hepatic function sufficiently to diminish the risks of subsequent operation.
Most patients with TS have coexisting valvular disease that requires surgery. Surgical treatment of TS should be carried out at the time of mitral valve repair or replacement in patients with TS in whom the mean diastolic pressure gradient exceeds 5 mm Hg and the tricuspid orifice is less than approximately 2.0 cm 2 . The final decision concerning surgical treatment is sometimes made at the operating table.
Because TS almost always is accompanied by some TR, simple finger fracture valvotomy may not result in significant hemodynamic improvement but may merely substitute severe TR for TS. However, open valvotomy or commissurotomy in which the stenotic tricuspid valve is converted into a functionally bicuspid valve may result in improvement, but annuloplasty may also be necessary if annular dilatation is present. The commissures between the anterior and septal leaflets and between the posterior and septal leaflets are opened. It is not advisable to open the commissure between the anterior and posterior leaflets for fear of producing severe TR. If open valvotomy does not restore reasonably normal valve function, the tricuspid valve may have to be replaced. A large bioprosthesis is preferred to a mechanical prosthesis in the tricuspid position because of the high risk of thrombosis of the latter and the longer durability of bioprostheses in the tricuspid than in the mitral or aortic positions. Tricuspid balloon valvuloplasty is feasible, but has limited efficacy as it may result in significant TR. It may be considered in the rare patient without TR, but because of lack of long-term outcome data, surgical therapy is preferred.
Tricuspid Regurgitation
Causes and Pathology
A trivial to mild degree of TR is commonly seen with echocardiography in patients with a normal right heart and structurally normal tricuspid valve. This is of no consequence and under normal conditions, does not increase in severity. However, various conditions can lead to greater degrees of TR. The most common cause of TR is not intrinsic involvement of the valve itself (i.e., primary TR) but rather dilation of the right ventricle and of the tricuspid annulus causing secondary (functional) TR (see Table 77.2 ). Right heart dilatation may result from volume overload as seen with left-to-right shunts in atrial septal defects or anomalous pulmonary venous connections. Dilatation may be a complication of RV failure of any cause (see Fig. 16.48). It is observed in patients with RV hypertension secondary to any form of cardiac or pulmonary vascular disease. Thus, secondary TR may be seen in left-sided valve disease, acute or chronic pulmonary thromboembolic disease, or chronic obstructive lung disease. , In general, a RV systolic pressure greater than 55 mm Hg will cause functional TR. TR can also occur secondary to RV infarction, congenital heart disease (e.g., pulmonic stenosis [PS] and pulmonary hypertension secondary to Eisenmenger syndrome; see Chapter 82 ), primary pulmonary hypertension (see Chapter 88 ) and cor pulmonale. In infants, TR may complicate RV failure secondary to neonatal pulmonary diseases and pulmonary hypertension with persistence of the fetal pulmonary circulation. In all these cases, TR reflects the presence of, and in turn aggravates, severe RV failure. Functional TR may diminish or disappear as the right ventricle decreases in size with the treatment of heart failure. TR can also occur as a consequence of dilation of the annulus in the Marfan syndrome, in which RV dilation secondary to pulmonary hypertension is not present. Acute or chronic AF can also lead to functional TR from tricuspid annulus dilatation, and AF is an important cause of isolated TR. ,
TABLE 77.2
Causes and Mechanisms of Pure Tricuspid Regurgitation
Modified from Waller BF. Rheumatic and nonrheumatic conditions producing valvular heart disease. In Frankl WS, Brest AN, eds. Cardiovascular Clinics: Valvular Heart Disease: Comprehensive Evaluation and Management . Philadelphia, FA: Davis; 1989:35, 95.
| Causes |
| Anatomically Abnormal Valve |
|
| Anatomically Normal Valve (Functional, dilated annulus) |
|
| Mechanisms |
| Condition | Leaflet Area | Annular Circumference | Leaflet Insertion |
|---|---|---|---|
| Floppy | ↑ | ↑ | Normal |
| Ebstein anomaly | ↑ | ↑ | Abnormal |
| Pulmonary/right ventricular systolic hypertension | Normal | ↑ | Normal |
| Papillary muscle dysfunction | Normal | Normal | Normal |
| Carcinoid | ↓/Normal | Normal | Normal |
| Rheumatic | ↓/Normal | Normal | Normal |
| Infective endocarditis | ↓/Normal | Normal | Normal |
A variety of disease processes can affect the tricuspid valve apparatus directly and lead to regurgitation (primary TR). , Organic TR may occur on a congenital basis (see Chapter 82 ), as part of Ebstein anomaly, defects involving the atrioventricular canal, when the tricuspid valve is involved in the formation of an aneurysm of the ventricular septum, or in corrected transposition of the great arteries, or it may occur as an isolated congenital lesion. Rheumatic fever may involve the tricuspid valve directly. When this occurs, it usually causes scarring of the valve leaflets and/or chordae tendineae, leading to limited leaflet mobility and either isolated TR or a combination of TR and TS. Rheumatic involvement of the mitral, and often aortic, valves coexist.
TR may result from prolapse of the tricuspid valve caused by myxomatous changes in the valve and chordae tendineae; prolapse of the mitral valve is usually present in these patients as well. Prolapse of the tricuspid valve has been estimated to occur in 20% of all patients with mitral valve prolapse (MVP), but compared to MVP, diagnostic criteria are less well-defined. Tricuspid valve prolapse also may be associated with atrial septal defect.
Distortion of the tricuspid leaflets by transvenous pacemaker and defibrillator leads is an increasingly common cause of clinically significant TR. , Injury to the tricuspid valve or subvalvular apparatus may complicate endomyocardial biopsy.
TR or the combination of TR and TS is an important feature of the carcinoid syndrome ( Fig. 77.2 ; see also Fig. 16.49), which leads to focal or diffuse deposits of fibrous tissue on the endocardium of the valvular cusps and cardiac chambers and on the intima of the great veins and coronary sinus (see Chapter 52 ). The white, fibrous carcinoid plaques are most extensive on the right side of the heart, where they usually are deposited on the ventricular surfaces of the tricuspid valve and cause the cusps to adhere to the underlying RV wall, thereby producing TR. A similar process may affect the tricuspid valve in patients who have used drugs that increase serotonin levels or simulate its effect on serotonin receptors (see ). These include the anorectic drugs, fenfluramine and phentermine; ergot derivatives used for treating migraine headaches (ergotamine and methylsergide) or Parkinson disease (pergolide or cabergoline); or the synthetic stimulant and hallucinogen, 3,4-methylenedioxymethamphetamine (Ecstasy).
Other causes of TR include penetrating and nonpenetrating trauma, dilated cardiomyopathy, and infective endocarditis ( 
) (particularly staphylococcal endocarditis in intravenous drug users). Endomyocardial fibrosis with shortening of the tricuspid leaflets and chordae tendineae is an important cause of TR in tropical Africa, Asia, and South America. Less common causes of TR include cardiac tumors (particularly right atrial myxoma), endomyocardial fibrosis, methysergide-induced valvular disease, and systemic lupus erythematosus involving the tricuspid valve.
Clinical Presentation
The clinical stages of TR are depicted in Table 77.3 .
Symptoms
In the absence of pulmonary hypertension or RV failure, TR generally is well tolerated. When pulmonary hypertension and TR coexist, cardiac output declines and the manifestations of right-sided heart failure become intensified. Thus, the symptoms of TR result from a reduced cardiac output and from ascites, painful congestive hepatomegaly, and massive edema. Occasionally, patients exhibit throbbing pulsations in the neck, which intensify on effort and are caused by jugular venous distention, and systolic pulsations of the eyeballs also have been described. In the many patients with TR who have mitral valve disease, the symptoms of the latter usually predominate. Symptoms of pulmonary congestion may abate as TR develops but are replaced by weakness, fatigue, and other manifestations of a depressed cardiac output.
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