Valvular Heart Disease 心臟內科 張哲明醫師
Mitral Stenosis • The MV leaflets thicken, the commissures fuse, and the chordae tendineae thicken and shorten. • Almost always the result of rheumatic fever. • Less common causes include congenital MS, SLE, RA, atrial myxoma, and bacterial endocarditis.
Pathophysiology -1 • The normal area of the MV orifice is 4-6 cm2. • Pure MS develops in approximately 40% of all pts with RHD. • A latency period of 10-20 years, or more, after an episode of rheumatic fever; therefore, the onset of MS symptoms does not occur until then. • The orifice 2 cm2, an increase in LA pressure (LAP) is necessary for normal transmitral flow to occur. • Critical MS - the opening < 1 cm2, at this stage, a LAP of 25 mm Hg is required to maintain a normal cardiac output.
Pathophysiology -2 • LAP raises pulmonary venous and capillary pressures, resulting in exertional dyspnea. • As the disease progresses, chronic LAP leads to pulmonary hypertension, tricuspid and pulmonary incompetence, and eventual right heart failure.
Frequency - In the US: The prevalence of MS has decreased because of the decline in the occurrence of rheumatic fever in the US and developed countries. • Mortality/Morbidity - Without surgical intervention, the progressive nature of the disease results in an 85% mortality rate 20 years after the onset of symptoms. • Sex - 2/3 of all patients with MS are female. • Age - the onset of symptoms usually is between the third and fourth decades.
Clinical • History - Hx of acute rheumatic fever. • History of murmur • Effort-induced dyspnea - Most common complaint. - Often triggered by exertion, fever, anemia, onset of Afib, or pregnancy. • Orthopnea • Chest pain due to RV ischemia, concomitant coronary atherosclerosis, or a coronary embolism. • Thromboembolism may be the first symptom of MS. • Palpitations • Recumbent cough
Physical • Peripheral and facial cyanosis • Jugular venous distention • Resp. distress, evidence of pulmonary edema (eg, rales) • Digital clubbing • Systemic embolization • Signs of right heart failure in severe MS include ascites, hepatomegaly, and peripheral edema. • If pulmonary hypertension is present, there may be a RV lift; an increased pulmonic S2 sound; and a high-pitched, decrescendo, diastolic murmur of pulmonary insufficiency (ie, Graham Steell's murmur).
Heart Murmur • Diastolic thrill that is palpable over the apex • A loud S1, followed by an S2, and the opening snap are best heard at the left sternal border. • This is succeeded by a low-pitched, rumbling, diastolic murmur, which is heard best over the apex while the patient is in the left lateral decubitus position. • This may diminish in intensity as the stenosis increases. • The duration, not the intensity, of the diastolic murmur correlates with the severity of the mitral narrowing. • The holosystolic murmur of MR may accompany the valvular deformity of MS.
Imaging Studies • Chest x-ray - Signs of pulmonary overload include: (1) prominence of pulmonary arteries, (2) enlargement of RV, and (3) evidence of CHF (eg, interstitial edema with Kerley B lines). - LA enlargement with straightening of the left heart border - Double density - Elevation of the left main stem bronchus - Pulmonary venous pattern changes with redistribution of the flow toward the apices - Prominent pulmonary arteries at the hilum, then they rapidly taper.
Mitral Stenosis - LA border is prominently convex
Echocardiography - the most sensitive and specific noninvasive method - the size of the mitral orifice can be measured - color doppler can evaluate the transvalvular gradient, pulmonary artery pressure, and accompanying MR. - Transesophageal echocardiography (TEE) is useful for detecting vegetations that are smaller than 5 mm or thrombi in the left atrium, which are not seen with transthoracic echocardiography.
Electrocardiogram - an enlarged left atrium is signified by a broad notched P wave, which is most prominent in lead II, with a negative terminal force in V1. - With severe pulmonary hypertension, right axis deviation and RV hypertrophy can be seen. - Atrial fibrillation is a common but nonspecific finding in MS.
Cardiac Catheterization - Increased left atrial or pulmonary capillary wedge pressure (PCWP) - Increased left atrial or PCWP to left ventricular pressure gradient - Calculated mitral valve orifice area - Calcified mitral valve - Concomitant mitral regurgitations - Presence of coronary artery disease (CAD)
Complications • Mural thrombi - 20% of pts, at high risk for embolization are those aged over 35, those with Afib and a low cardiac output, and those having a large LA appendage. • Development of Atrial fibrillation - up to 40% of pts. - Loss of atrial contraction with the development of Afib cardiac output by 20% - Since cardiac output is related to the heart rate, Afib with a rapid ventricular response diastolic filling time and further compromises cardiac output
Medical Treatment • Rate control : - Digitalis. - Beta-blocker. - Calcium channel blocker, in patients with a beta-blocker contraindication. (eg, diltiazem) • Diuresis for signs of pulmonary edema. • Anticoagulation : Anticoagulation is helpful in preventing thrombus formation and embolization in pts with Afib.
Interventional treatment • Balloon valvulotomy - It most commonly is used in young pts without extensive valvular calcification, in pregnant women, and in pts who are unfavorable operative candidates • Mitral valve replacement - performed if leaflets are immobile or heavily calcified. - It also is performed if there is severe subvalvular scarring. - Bioprosthetic or artificial mechanical valves can be used as replacements.
Percutaneous Transluminal Mitral Valvuloplasty
Mitral Regurgitation • Causes: - Acute rheumatic heart disease ( < 40 y/o) - Mitral valve prolapse (ie, myxomatous degeneration) - Myxomatous degeneration, cause unknown, often is a slow process, with a complication being the rupture of the chordae tendineae. - Acute MR, can be caused by a chordae tendineae rupture or papillary m. dysfunction. - Ischemia is responsible for 3-25% of MR, severity is directly proportional to the amount of LV hypokinesis.
- Mitral annular calcification can contribute to regurgitation. - Impaired constriction of the annulus results in poor valve closure. - LV dilatation and heart failure can also produce annular dilatation and poor valve closure resulting in MR. - Tendineae rupture can be due to endocarditis, myocardial infarction, or trauma. - Papillary m. dysfunction usually is caused by infarction.
Acute MR Chronic MR Lung edema with normal heart size Diffuse dilatation of the heart
History and Physical Examination - A high-pitched "blowing" holosystolic murmur is common. - the intensity of the murmur does not correlate well with the severity of the MR. - A 3rd heart sound indicates a large LV filling volume, and its prevalence increases with increasing severity of the MR • Echocardiography - determine the presence, severity, and mechanism of MR - size of the LA and LV and the degree of pulmonary HTN • Catheterization is necessary only in pts being referred to surgery
Pathophysiology and Natural History • Chronic MR - LV undergoes adaptive changes, such as chamber dilatation and eccentric hypertrophy. - EDV early, but the ESV & EF initially remain normal - LV myocardial contractility slowly over time, while the pt remains asymptomatic. Later, symptoms develop and the depressed LV contractility becomes irreversible - The natural hx of chronic MR depends on its cause and severity and on LV function. - severe asympt. or minimally sympt. MR due to MV prolapse, dz progresses to OP is required at a rate of about 10%/year.
Severe MR, with a flail leaflet and NYHA class III or IV suggest a high risk (an annual mortality rate of 34%), which contrasts greatly with the 4% rate for pts with class I or II symptoms.
Medical Treatment - Optimum medical management of patients with severe asymptomatic MR is controversial. - If HTN or LV dysfunction(+), treatment with afterload reduction is indicated. - In other pts, the use of afterload reduction is controversial, since there are no data to suggest that vasodilator therapy reduces the need for surgery. - ACEI may reduce the MR fraction and LV cavity size in some pts, especially if they have symptoms or an enlarged LV.
Surgical Treatment - The 1o indications for OP in severe MR are the development of symptoms or LV dysfunction. - The ideal time to operate is during transition from the chronic compensated state to the decompensated state. - The best results are achieved in pts with an EF > 60% and an end-systolic size < 4.5 cm. - Recent literature suggests a trend toward repairing the valve while the pt is still asymptomatic.
Aortic Stenosis - Aortic stenosis (AS) is the obstruction of blood flow across the aortic valve. - AS has several etiologies: congenital uni- or bicuspid valve, rheumatic fever, and degenerative calcific changes of the valve. • Frequency: - AS exists in up to 2% of those < than 70 yrs. - The etiology of AS in those aged 30-70 yrs can be rheumatic disease or calcification of a congenital bicuspid valve. - > 70 yrs, degenerative calcification is the primary cause of AS. - Among people older than 75 years, 3% have critical AS. - Among children, 75% of cases of AS are in males.
History: - usually has an asymptomatic latent period of 10-20 years. - the classic triad of chest pain, heart failure, and syncope. - May have a higher incidence of nitroglycerine-induced syncope. • Mortality/Morbidity: - Sudden cardiac death occurs in 3-5% of patients with AS. - Adults with AS have a 9% mortality rate per year. - Once symptoms develop, the incidence of SCD increases to 15-20%, with less than a 5-year survival rate. - Pts with exertional angina, syncope, and CHF have an average of 5, 3, 2 years survival respectively.
Pathophysiology: - Stenosed AV, resistance to systolic ejection occurs and a systolic p. gradient develops between the LV and the aorta. - aperture that leads to a progressive LV systolic p. - pressure overload in the LV, causes an in ventricular wall thickness (ie, concentric hypertrophy), no chamber dilatation and ventricular function is preserved at this time. - Eventually, the LV dilates; increase in LV end-diastolic pressure. - A sustained pressure overload eventually leads to myocardial decompensation. - myocardium contractility, which leads to a decrease in cardiac output, LVEDP, PCWP, EF & C.O - Ultimately, congestive heart failure occurs.
Physical : • Palpation - laterally displaced apex (LVH); systolic thrill (at the base, the jugular notch, and along the carotid a.) • Auscultation - Crescendo-decrescendo systolic ejection murmur (loudest at the base of the heart and most commonly is appreciated in the 2nd Rt intercostal space); S3 (LV dilates and fails); S4 (LVH) • Pulsus parvus et tardus - arterial pulse with a delayed and plateaued peak, decreased amplitude, and a gradual downslope.
A, Normal aortic valve B, Congenital AS C, Rheumatic AS D, Calcified AS E, Calcified senile AS
Imaging Studies: • Chest x-rays - may show cardiac enlargement, more severe stages of AS, signs of LAE, PA enlargement, Rt-sided enlargement, and pul. congestion are evident. • Echocardiographs - An echo-dense aortic valve with no cusp motion, max. aortic cusp separation (less than 8 mm in the adult) is also indicative of severe AS, LVH, systolic P.G across the AV. • Electrocardiogram - LVH / strain pattern, 13% have conduction defects, LAE (mitral valve process)
Aortic Stenosis - rounded LV border (LVH) - prominent proximal ascending aorta ( post-stenosis dilatation)
Cardiac Catheterization - surgery, suspected of having CAD, and > 40 years (even without significant symptoms). - 50% incidence of underlying CAD. - OP is routinely recommended when a cross-sectional area is 0.8-1.9 cm. - unlike PBMC for treating mitral stenosis, valvuloplasty has been largely unsuccessful for treating aortic stenosis. (associated with a high risk of bleeding and embolic complications, and the 6-month success rate is dismally low)
Surgical Treatment - AS must be thought of as a surgical disease, since there are few medical alternatives to surgery and no medical treatments that positively affect survival. - Surgery is indicated when symptoms are present together with severe stenosis, as measured by echocardiography or catheterization. - The prognosis without surgery is poor.
Aortic Regurgitation • Background: - AR is the diastolic flow of blood from the aorta into the LV. - incompetence of the AV or any disturbance of the valvular apparatus (eg, leaflets, annulus of the aorta), resulting in diastolic flow of blood into the LV chamber. • Pathophysiology: - The most common cause of chronic AR used to be RHD. - Presently, it is most commonly caused by bacterial endocarditis - In developed countries, it is caused by dilatation of the ascending aorta
- AR may be a chronic disease process or it may occur acutely, presenting as heart failure. - Diastolic reflux through the AV can lead to LV volume overload. - The severity of the AR is dependent on the diastolic valve area, the diastolic pressure gradient between the aorta and LV, and the duration of diastole.
Causes: • Acute AR - rheumatic, infective endocarditis, ruptured sinus of Valsalva, trauma, prosthetic valve surgery,aortic dissection, laceration of the aorta • Chronic AR • rheumatic, syphilis, aortitis (ie, Takayasu disease), Marfan syndrome, osteogenesis imperfecta, bicuspid aortic valve, VSD, sinus of Valsalva, ankylosing spondylitis, Reiter syndrome, Rheumatoid arthritis, SLE, Hypertension, Infective endocarditis
Mortality/Morbidity: - 3/4 of patients with significant AR survive 5 years after Dx. ; half survive for 10 years. - mild-to-moderate AR survive 10 years in 80-95% of the cases. - Average survival after onset of CHF is less than 2 years. - Acute AR is associated with high morbidity, which can progress from pulmonary edema to refractory heart failure and cardiogenic shock. • Age: - Chronic AR often begins in the late 50s and is documented most frequently in patients older than 80 years.
Clinical • Physical: • The hallmark is a high-pitched decrescendo diastolic murmur at the left sternal border after the 2nd heart sound. • Acute AR - severe AR associated with CHF and/or shock often will appear gravely ill. - Tachycardia, cyanosis, pulmonary edema, arterial pulsus alternans, early diastolic murmur, Austin-Flint murmur • Chronic AR - All auscultatory phenomena indicate vasodilatation of peripheral circulation. - Decrescendo diastolic murmur
- Pulsus bisferiens: increased pulse pressure; visible, forceful, and bounding peripheral pulses (water hammer) - Corrigan’s pulse: the carotid pulse has a rapid rise & full upstroke with a rapid fall in diastole - de Musset sign: Bobbing of the head - Quincke sign: Capillary pulsations of the nail bed - Muller sign: Pulsations of the uvula - Hill sign: Systolic pressure in lower extremity greater than upper extremity by 20 mm Hg - Traube sign: Loud systolic sound over femoral arteries - Duroziez’s sign: Compression of femoral artery with a stethoscope produces a systolic-diastolic murmur - Pistol-shot femoral pulses
Austin-Flint murmur - a low pitched diastolic rumble ( similar to MS murmur; indicates mod. to severe AR. • Diagnosis • Electrocardiography - usually shows LVH • CXR - proximal aorta dilated and LV dilatation • Echocardiography • Cardiac catheterization
Aortic Regurgitation - a Marfan synd. p’t - prominent LV border (LV dilatation) - ascend. aorta is convex - dilated descend. aorta
Medical Treatment - AR is the only valvular disease in which medical therapy (ie, afterload reduction) is proven to alter the natural history. - The agent most studied is nifedipine; In a study comparing it with digoxin, nifedipine was shown to significantly delay the need for aortic valve replacement in pts with severe asymptomatic aortic insufficiency, also had relatively smaller ventricle size and higher ejection fraction.
Indications for Surgery - As in pts with severe MR, the preoperative size of the LV in pts with AR is directly related to the postoperative EF, but with two important differences. - Pts with AR may have larger ventricles preoperatively and maintain normal EF postoperatively. - Also, if the EF has been reduced for < 12 to 14 mo., it may return to normal postoperatively. - Asymptomatic pts with normal LV function have an excellent prognosis, even in the presence of mild cardiac enlargement.
- The indications for valve replacement in pts with severe AR include : 1) the onset of symptoms, 2) (+) LV dysfunction (EF <50%), and 3) (+) severe LV dilatation (end-systolic size >5.5 cm). - Once significant LV systolic dysfunction is present, surgical outcome is less satisfactory.