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Pulmonary Stenosis


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Pulmonary Stenosis

  1. 1. New Page 1 file:///C:/Documents%20and%20Settings/Linda/Desktop/pspi/pspi.html 1 of 7 2/15/2003 2:55 PM Pulmonary Stenosis Etiology and Pathology Right ventricular outflow tract obstruction can occur either at the pulmonary valve level, narrowing of the infundibular portion of the right ventricle or both or narrowing of the pulmonary artery and its branches. In pulmonary valve stenosis the valve is usually tricuspid and the valve cusps are fused along the margins to form an obstructing diaphragm. The valve orifice size may vary from 2-10 mm in diameter. The valve may tend to become thickened and calcified. Right ventricular hypertrophy will develop with time even if the orifice is mildly narrowed. Dilatation of the pulmonary arteries beyond the valve occurs gradually. Rarely, pulmonary valve stenosis may be due to carcinoid syndrome. Infundibular stenosis may be due to hypertrophy of the outflow tract. Obstruction may rarely occur if there is a compression externally from a tumor or aberrant muscle bundle within the right ventricle. Infundibular stenosis may develop in patients with a large left to right shunt due to ventricular septal defects, or may be present in hypertrophic cardiomyopathy. As an isolated defect it is rare. There is usually no post-stenotic dilatation present. Supravalvular pulmonary artery stenosis or stenosis of the pulmonary artery may occur as single or multiple lesions located anywhere from the main pulmonary trunk to the smaller peripheral arterial branches Associated defects are observed in most patients and include pulmonic valvular stenosis, ventricular septal defect, tetralogy of Fallot, and supravalvular aortic stenosis. The most important cause of significant pulmonary artery stenosis producing symptoms in the newborn is intrauterine rubella infection. Rubella syndrome consists of deafness, cataracts, pulmonary artery stenosis, thrombocytopenia, hepatitis. Williams syndrome also includes not only supravalvular aortic stenosis by also pulmonary artery stenosis may be present. William's syndrome involves chromosome number 7. Obstruction within the pulmonary arterial tree may be classified into four types: (1) stenosis of the main pulmonary trunk or the main left or right branch (2) narrowing at the bifurcation or the pulmonary artery, extending into both right and left branches (3) multiple sites of peripheral branch stenosis and (4) a combination of main and peripheral stenosis. Pulmonary artery obstruction may be produced by localized narrowing, diffuse constrictions, or, rarely, a membrane or diaphragm. Poststenotic dilatation is usual when the stenosis is localized by may be absent or minimal with elongated constriction, The congenital form of pulmonic (PS) is the most common cause in children. In children valvular pulmonic stenosis, resulting from fusion of the valve cusps during mild to late pregnancy, is the most common form of isolated right ventricular obstruction and occurs at about 7 percent of patients with congenital heart disease. Hypertrophy of the septum and parietal bands narrowing the right ventricular infundibulum often accompanies the pulmonic valve lesion, especially if it is severe. Rheumatic inflammation of the pulmonic valve is very uncommon, is usually associated with involvement of other valves, and rarely leads to serious deformity. Carcinoid plaques, similar to those involving the tricuspid valve, are often present in the outflow tract of the right ventricle inpatients with malignant carcinoid and result in constriction of the pulmonic valve ring, retraction and fusion of the valve cusps, and either PS or the combination of PS and pulmonic regurgitation (PR). Signs and Symptoms In the majority of adults with pulmonary valve stenosis, even with significant obstruction, deny symptoms. Occasionally patients may complain of fatigue or dyspnea. The presence of angina or syncope would indicate severe obstruction as would the development of right heart failure.
  2. 2. New Page 1 file:///C:/Documents%20and%20Settings/Linda/Desktop/pspi/pspi.html 2 of 7 2/15/2003 2:55 PM Heart Sounds Most patients with right ventricular outflow obstruction present in adult life are detected because of the chance finding of a murmur. The murmur is a mid-systolic ejection click in type and finishes before pulmonary valve closure and it usually increases in intensity with inspiration . In mild or moderate pulmonary valve stenosis, the second heart should is abnormally widely split in expiration, though the split widens further on inspiration as would occur in normal patients. The severity of the stenosis determines the width of splitting: the wider the expiratory split, the more severe the stenosis. Pulmonary valve closure becomes inaudible when the stenosis is very severe. The abrupt halting of the abnormal pulmonary valve at the onset of systole gives rise to a pulmonary ejection sound. In infundibular stenosis the ejection sound will be absent. Associated right ventricular hypertrophy may be detected by palpation and would give rise to abnormal dominance of the 'a' wave in the venous pulse. Laboratory Examinations Electrocardiography The electrocardiogram in mild or moderate pulmonary stenosis may be normal. In severe pulmonary stenosis, right ventricular hypertrophy is usually present. In severe cases with right heart dilatation, right atrial enlargement may be present in addition to right ventricular hypertrophy. Chest X-ray Pulmonary valve stenosis is characterized on the chest x-ray by a normal sized heart with post-stenotic dilatation of the pulmonary trunk, characteristically extending into the left branch. Pulmonary artery
  3. 3. New Page 1 file:///C:/Documents%20and%20Settings/Linda/Desktop/pspi/pspi.html 3 of 7 2/15/2003 2:55 PM dilatation in come cases may be gross. Pulmonary oligemia may sometimes be visible. Cardiac Catheterization The right ventricular outflow tract obstruction is detected at cardiac catheterization by a systolic pressure difference. The site of obstruction will also be determined. On right ventricular angiography the site of the outflow obstruction can be seen when it is at valve level, Infundibular level or in the right ventricular cavity. In pulmonary valve stenosis the cusps will be thickened, domed in systole, with a central jet and post-stenotic dilatation of the pulmonary artery. Pulmonary Insufficiency Hemodynamically severe pulmonary insufficiency (PI) is a rare finding and rarely caused by the primary pathologic process and usually appears secondary to pulmonary hypertension (PHTN). Etiology and Pathology The primary cause of pulmonary insufficiency is the dilatation of the pulmonary ring due to pulmonary hypertension. Endocarditis which may show vegetations on the flow side of the cusps and is the second most common etiology. Pulmonary insufficiency can also occur because of connective tissue disease such as Marfan's syndrome. It may also occur in conjunction with valvular pulmonary stenosis, post-valvotomy. It is found in 87% of the population. Pathophysiology Unless pulmonary hypertension occurs, the right ventricle volume overload resulting from pulmonary insufficiency may be tolerated for a long time. When pulmonary hypertension appears then right heart failure develops relatively soon. Signs and Symptoms Pulmonary insufficiency causes few problems and is relatively asymptomatic until very late in the disease. Dyspnea on exertion occurs due to pulmonary hypertension in severe cases and because of severe pulmonary hypertension, acities, and fluid retention. Right ventricular failure can eventually result because of the pulmonary hypertension. The diagnosis is very incidental compared t the more dominant problems of right heart failure.
  4. 4. New Page 1 file:///C:/Documents%20and%20Settings/Linda/Desktop/pspi/pspi.html 4 of 7 2/15/2003 2:55 PM Heart Sounds When associated with pulmonary artery dilation and pulmonary hypertension, PR leads to an early diastolic, decrescendo murmur in the left sternal boarder. The murmur is called a Graham Steell murmur and usually is associated with other signs of pulmonary hypertension. Severe pulmonary hypertension usually is indicated with a right ventricular systolic pressure of >70 mm Hg. The PR murmur in association with normal pulmonary pressures tends to be mid-diastolic, with a crescendo-decrescendo pattern. The murmur is difficult to differentiate from aortic insufficiency; in one study, the examiner was correct only 25% of the time. Right Heart Disease Right-sided heart disease encompasses a wide variety of disorders, most of which have similar clinical manifestations in their late stages. The spectrum of right heart conditions include pulmonary hypertension of many causes, cor pulmonale, and primary tricuspid and pulmonic valve disease. Cor pulmonale, i.e., right heart disease due to pulmonary hypertension in the absence of left heart disease, implies right ventricular (RV) enlargement. The current discussion will address pulmonary hypertension and cor pulmonale since tricuspid and pulmonic disease has been reviewed in previously. Etiology Pulmonary hypertension is the major cause of RV dysfunction and is classified as primary (rare 2 million population) or secondary which is more prevalent. Pulmonary hypertension results from an increased resistance to blood flow at any number of sites within the circulation and pulmonary vascular bed representing only one of these potential sites. The pulmonary circulation is a low pressure, low resistance circulation which perfuse the lungs for oxygenation and elimination of CO2. In addition to increased resistance (pressure) to blood flow, markedly increased flow (volume) alone can cause pulmonary hypertension, even when resistance to flow is normal at every point in the circulation. There are 5 etiologies based on different locations within the heart and conditions of the patients: 1. Increased resistance to pulmonary venous drainage: a. mitral stenosis b. left atrial hypertension c. left ventricular Failure d. reduced Left ventricular compliance (increased LVEDP) due to infarction, CAD, age, and acute AI e. left atrial myxoma f. mitral regurgitation g. Cor Triatriatum h. aortic stenosis i. CAD j. constrictive pericarditis k. cardiomyopathy l. LV Diastolic Failure m. pulmonary venous obstruction due to congenital stenosis of pulmonary veins or outward compression from another source. 2. Increased resistance to pulmonary vascular flow: such as decrease cross sectional area or constriction of pulmonary vascular beds secondary to parenchyma disease:
  5. 5. New Page 1 file:///C:/Documents%20and%20Settings/Linda/Desktop/pspi/pspi.html 5 of 7 2/15/2003 2:55 PM a. COPD, Cor pulmonale (Parenchyma disease of the lung) Chronic Bronchitis, emphysema destroying pulmonary capillary beds b. restrictive Lung disease (carcinoma, sarcoidosis, collagen vascular disease) c. hepatic cirrhosis, Portal thrombosis d. Eisenmenger Syndrome - patient with congenital lesions (VSD, ASD, or PDA or both) severe PHTN where reversal of a left to right shunt occurs and there is equalization of pressures beyond surgery 3. Increased resistance to flow through pulmonary artery: a. pulmonary emboli acute or chronic b. peripheral pulmonic stenosis 4. Hypoventilation: a. obesity b. pharyngeal - Tracheal obstruction c. chest wall disorders d. neuromuscular - myasthenia gravis e. sleep apnea 5. Miscellaneous: a. high altitudes b. isolated anomalous pulmonary venous return c. tetrology of Fallot d. IV drug abuse e. Takayasu's disease RV dysfunction may occur when there is ischemia or infarction of the RV, or chronic pressure of volume overload of the RV, or chronic pressure or volume overload of the RV. Arrhythmogenic RV cardiomyopathy (ARVC) also results from the progressive loss of RV cells. the myocardium is slowly replaced by non contractile fibrous tissue. Chronic dilatation of the RV in the absence of elevated pulmonary artery pressure can result from chronic RV volume overload. Disorders that lead to volume overload include ASD, Ebstein anomaly, partial anomalous pulmonary venous return, tricuspid regurgitation (TR), and pulmonic insufficiency (PI). The latter two conditions may be caused by endocarditis, carcinoid syndrome, iatrogenic or traumatic disorders, rheumatic valve disease, and congenital abnormalities. Signs and Symptoms Although the spectrum of diseases associated with RV dysfunction is wide, the late stages of nearly all forms of right heart disease have similar symptoms. Development of RV dysfunction results in fatigue, which is the most commonly reported symptom. As RV dysfunction progresses, patients may complain of a full neck (distended jugular veins), lower extremity edema, and right upper quadrant pain. Hepatic congestion may lead to ascities, and patients will complain of increasing abdominal girth. These symptoms are common to all forms of right heart disease and are not helpful for determining the specific underlying etiology. Symptoms of coronary artery disease should be sought in patients with unexplained right heart failure. They may have a history of prior myocardial infarction or symptoms of exertional angina or dyspnea.
  6. 6. New Page 1 file:///C:/Documents%20and%20Settings/Linda/Desktop/pspi/pspi.html 6 of 7 2/15/2003 2:55 PM Pulmonary hypertension related to pulmonary venous congestion from left heart disease leads to symptoms of left-sided failure either before or concurrent with symptoms of right heart failure. Symptoms of left-sided heart failure include shortness of breath, dyspnea of exertion, orthopnea, and paroxysmal nocturnal dyspnea (PND). symptoms of angina or a prior history of myocardial infarction are important. Patients also may complain of palpitations, PND, or fatigue due to atrial arrhythmias. Patients with primary pulmonary hypertension or COPD have symptoms of dyspnea in the absence of significant orthopnea or PND. Severe pulmonary hypertension of any cause may be associated with chest pain, especially with exercise, that presumably is related to RV subendocardial ischemia. syncope and presyncope are fairly common features of advanced pulmonary hypertension. Pulmonic valvular disease may be entirely asymptomatic and only recognized on the cardiac physical examination. Cyanosis is fairly common and is reported in about 30% of cases due to shunting through a patent foramen ovale. Epistaxis (hemorrage from the nose) and clubbing are other features of pulmonic valvular disease. Symptoms of right heart failure may occur eventually and are poor prognostic sign. TR may be due to RV pressure or volume overload and often results from tricuspid annular dilatation. TR due to carcinoid syndrome or endocarditis, however, has distinct signs and symptoms. Carcinoid syndrome has been discussed in an earlier module. A history of intravenous drug use and fever are the usual presenting historical features of tricuspid valve endocarditis. Physical Examination When discussing RV dysfunction an the resulting TR, it is useful to categorize patients into those with normal pulmonary artery pressure and those with pulmonary hypertension. Normal Pulmonary Artery Pressure In the absence of elevation of pulmonary artery pressure, the RV usually faces a pure volume overload. Volume overload may be the result of left to right shunting, TR, or PR. In general, the magnitude of TR is less than when pulmonary hypertension is present. The normal RV and right atrium (RA) are relatively compliant. Elevated Pulmonary Artery Pressure The RV in chronic severe pulmonary hypertension has increased systolic and diastolic pressures and volume (chamber dilation); ultimately, the tricuspid valve annulus dilates and TR develops. Decreased compliance of the hypertrophied RV will augment the magnitude of the TR. TR resulting from pulmonary hypertension tends to be more severe. In patients with rheumatic mitral valve diseae or chronic congestive heart failure, TR generally is present in subjects with mean RA pressures >10 mm Hg. Jugular Venous Pulse Neck vein pulsations in right heart disease are of major diagnostic importance. The diagnosis of TR often can be entertained prior to auscultation by careful examination of the jugular pulse. With increasing severity of TR, the accentuated jugular V wave appears during systole. As the severity of TR increases in magnitude the X descent becomes attenuated and ultimately disappears. The regurgitant V wave is systolic and simultaneous with the palpable carotid arterial pulse, although the precise timing , peak and contour are somewhat different from the arterial pulsations. Heart Sounds First Heart Sound (S1) RV hypertrophy or dilatation in the presence of right bundle branch block may be associated with a split S1. Second Heart Sound (S2) With pulmonary hypertension, an accentuated P2 often is present and may be widely transmitted over the precordium. If severe RV failure is present, RV ejection will be prolonged and the stroke volume relatively fixed during respiration. S2 will be widely Split both in inspiration and expiration. This can simulate the fixed splitting of an ASD. Third Heart Sound (S3)
  7. 7. New Page 1 file:///C:/Documents%20and%20Settings/Linda/Desktop/pspi/pspi.html 7 of 7 2/15/2003 2:55 PM RV S3 occasionally can be heard with RV dysfunction. The S3 may reflect the excessive volume of blood crossing the tricuspid valve in early diastole and/or RV decompensation associated with a large RV end-diastolic volume and decreased ejection fraction. Right sided S3 and S4 typically are louder during inspiration and wane with expiration. Such sounds may be audible only in inspiration. Fourth Heart Sound (S4) A right sided S4 may be heard in patients with acute-onset TR. This is similar to the left-sided S4 found in patients with acute mitral regurgitation. In such cases, the RV and the RA usually are of normal size. The regurgitant volume load results in vigorous RA contraction and produces a large increase in end-diastolic flow and pressure in the RV. Acute TR is likely to occur in a drug addict with tricuspid valve endocarditis or in a patient with traumatic rupture of a tricuspid valve. A right-sides S4 may be heard in patients with RV hypertension secondary to pulmonary stenosis or idiopathic pulmonary hypertension. This results from atrial contraction into a noncompliant RV. The right-sided S4 increases with inspiration. It may be quite loud.