Valvular Heart Disease PDF

VALVULAR HEART DISEASE Miriam Al Battal, MD Definition  Stenosis: failure of a valve to open completely, obstructing forward flow.  Insufficiency: failure of a valve to close completely, thereby allowing regurgitation (backflow) of blood.  clinical consequences of va...

VALVULAR HEART DISEASE Miriam Al Battal, MD Definition  Stenosis: failure of a valve to open completely, obstructing forward flow.  Insufficiency: failure of a valve to close completely, thereby allowing regurgitation (backflow) of blood.  clinical consequences of valve dysfunction depends: valve involved degree of impairment Tempo of disease onset Calcific Aortic Stenosis  most common of all valvular abnormalities  age-associated  “wear and tear” of either anatomically normal valves or congenitally bicuspid valves  seventh to ninth decades of life  stenotic bicuspid valves : one to two decades earlier. Etiology ❑ Chronic progressive injury: Hyperlipidemia, Hypertension….  deposition of hydroxyapatite (the same calcium salt found in bone). MORPHOLOGY  Calcified masses on the outflow surfaces of the cusps that ultimately prevent cuspal opening.  free edges of the cusps are usually not involved  Microscopically: layered architecture of the valve is largely preserved.  Calcification begins in the valvular fibrosa on the outflow surface of the valve, at the points of maximal cusp flexion (near the margins of attachment). In contrast with rheumatic (and congenital) aortic stenosis commissural fusion is not usually seen. Hemodynamic changes  Left ventricular increase pressure overload → producing concentric left ventricular hypertrophy. Consequences  Increased LV oxygen demand → hypertrophied myocardium tends to be ischemic  Impaired ventricular filling during diastole → left heart failure  Angina pectoris may occur.  Syncope & exertional dyspnea  Both systolic and diastolic myocardial function may be impaired; eventually, cardiac decompensation and CHF can ensue.  Calcific Stenosis of Congenitally Bicuspid Aortic Valve  1% of the population  two functional cusps of unequal size  larger cusp having a midline raphe, resulting from incomplete commissural separation during development;  raphe : major site of calcific deposits Mitral stenosis  Chronic Rheumatic Mitral Valvar Disease ❖ thickening of the leaflets ❖ fusion of the ends of the zones of apposition (so-called commissural fusion) ❖ Shortening and fusion of tendinous cords Valvar scarring and fibrosis ❑ Chronic pulmonary congestion and passive pulmonary hypertension, and consequently to right ventricular hypertrophy. ❑ Atrial fibrillation, due to the increase of left atrial volume. Aortic regurgitation  Aortic regurgitation (AR) is characterized by regurgitation of blood from the aorta to the left ventricle (LV) during diastole Aortic regurgitation ❑ intrinsic disease of the valve leaflets Rheumatic heart disease Infective endocarditis ❑ Aortic disease: Degenerative aortic dilation (aging and hypertension) Syphilitic aortitis Ankylosing spondylitis Rheumatoid arthritis Marfan syndrome  Acute Aortic Regurgitation  Most commonly caused by bacterial endocarditis, aortic dissection, or blunt chest trauma (Aortic dissection should always be suspected in patients with AR and chest or back pain)  Sudden large regurgitant volume is imposed on an LV of normal size that has not had time to accommodate the volume overload → resulting in an acute increase in LV diastolic pressure and a fall in forward cardiac output  Inability of ventricle to develop compensatory chamber dilatation acutely results in a decrease in forward stroke volume.  Tachycardia may develop as a compensatory mechanism to maintain cardiac output, but often insufficient. Acute AR - Pathophysiology  Patients often present with pulmonary edema or cardiogenic shock.  LV dilation and thinning of LV wall combined with tachycardia leads to increased myocardial O2 demand  Ischemia and its consequences, including sudden death, occur commonly in acute AR.  Chronic Aortic Regurgitation  Chronic AR imposes both volume and pressure overload on the LV.  the volume overload (Increased regurgitant volume ) of the left ventricle (LV) → gradual increase in LV size → normal forward cardiac output despite the regurgitant valve flow  LV diastolic pressures remain normal.  Compensatory eccentric hypertrophy occurs→ maintain normal stroke volume with the chamber enlargement Chronic AR - Pathophysiology Decompensated  LV systolic dysfunction accompanied by decreased LV diastolic compliance due to hypertrophy and fibrosis  Leads to high filling pressures and CHF symptoms Mitral valve regurgitation Etiology  A dysfunction of any portions of the mitral valve apparatus can cause mitral regurgitation.  The most common cause of mitral regurgitation is mitral valve prolapse (MVP) Other causes: pathophysiology of mitral regurgitation three phases  acute phase  chronic compensated phase  chronic decompensated phase Acute mitral regurgitation  Ex: sudden rupture of a chorda tendinea or papillary muscle  sudden volume overload of both the left atrium and the left ventricle.  the stroke volume of the left ventricle is increased (increased ejection fraction) PV  Acute mitral regurgitation  Due to the added regurgitant vol there is ↑ in LV volume that leads to an ↑ in LV cavity pressure and it causes an ↑ in wall stress  Increased LV wall stress→ deterioration of the LV contraction → dysfunctional LV and a decrease in ejection fraction.  The increased pressures in the left atrium inhibit drainage of blood from the lungs via the pulmonary veins.  This causes pulmonary congestion.  Cardiovascular collapse with shock (cardiogenic shock) may be seen in individuals with acute mitral regurgitation  Chronic phase Compensated:  develops slowly over months to years  left ventricle → eccentric hypertrophy (in order to better manage the larger than normal stroke volume).  In the left atrium, the volume overload causes enlargement of the chamber of the left atrium, allowing the filling pressure in the left atrium to decrease.  This improves the drainage from the pulmonary veins, and signs and symptoms of pulmonary congestion will decrease.  Individuals in the chronic compensated phase may be asymptomatic and have normal exercise tolerances.  Chronic phase Decompensated:  the hallmark for the chronic decompensated phase: left ventricular dysfunction.  the ventricular myocardium is no longer able to contract adequately to compensate for the volume overload of mitral regurgitation, and the stroke volume of the left ventricle will decrease.  The decreased stroke volume causes a decreased forward cardiac output and an increase in the endsystolic volume. The increased end-systolic volume translates to increased filling pressures of the left ventricle and increased pulmonary venous congestion.  In addition : left ventricle begins dilatation →dilatation of the mitral valve annulus, which may worsen the degree of mitral regurgitation.  The individual will have symptoms of congestive heart failure: shortness of breath, pulmonary edema, orthopnea, as well as symptoms suggestive of a low cardiac output state (i.e. decreased exercise tolerance). Mitral Valve Prolapse (Myxomatous Degeneration of the Mitral Valve)  one or both mitral valve leaflets are “floppy” and protrude into the left atrium during systole.  it is more common in women  Incidental finding on physical examination (mid-systolic clicks) Pathogenesis  unknown in most cases  Uncommonly, associated with heritable disorders of connective tissue including Marfan syndrome.  MORPHOLOGY  The characteristic anatomic change in MVP is ballooning (hooding) of the mitral leaflets  leaflets are often enlarged, redundant, thick, and rubbery.  tendinous cords may be elongated & thinned  key histologic change : marked myxomatous degeneration of the spongiosa layer, reflected by increased deposition of a highly sulfated hydrophilic matrix  Collagenous fibrosa layer of the valve is also attenuated, affecting the structural integrity of the leaflet.  Secondary changes stresses and tissue injury incident to the billowing leaflets:  fibrous thickening of the valve leaflets  thickening of the mural endocardium of the left ventricle or atrium as a consequence of friction-induced injury induced by the prolapsing, hypermobile leaflets;  thrombi on the atrial surfaces of the leaflets or the atrial walls  focal calcifications  Mitral Annular Calcification  degenerative calcific deposits typically develop in the fibrous annulus.  stony hard nodule (2 to 5 mm) at the base of the leaflets  Mitral annular calcification usually does not affect valvular function.  Complications: ❑ a site for thrombus formation, ❑ a nidus for infective endocarditis.  Exceptional complications: ❑ Regurgitation ❑ Stenosis by impairing opening of the mitral leaflets ❑ Arrhythmias and sudden death by penetration of calcium deposits to a depth sufficient to impinge on the atrioventricular conduction system  85 yo male KTH hypertension present to our ED for chest pain and dyspnea.  3 days ago he lost consciousness while climbing the stair  CXR shows mild pulmonary edema  Echo shows hypertrophied left ventricule What of the following is true? - His mitral valve is enlarged, redundant, thick, and rubbery - His aortic valve presents calcified masses on the outflow surfaces of the cusps - His mitral valve presents degenerative calcific deposits in the fibrous annulus - His mitral and aortic valve are normal