STS E Book - The Mitral Valve Flashcards
What are the trigones of the mitral valve
The two fibrous components whose limits define the fibrous portion of the mitral annulus
The right fibrous trigone of the mitral valve is part of the central fibrous body of the heart, in continuity with what structures (3)?
The aortic valve, the tricuspid valve, and membranous septum
What are the important markers of the mitral valve used for annuloplasty ring sizing? Why?
Intertrigonal distance, because the fibrous annulus remains unchanged across the spectrum of mitral disease
What are the papillary muscles that support the mitral valve? What is their blood supply?
Anterolateral - LAD and Cx
Posteromedial - PDA
What is the usual etiology of mitral stenosis?
Rheumatic fever in childhood or adulthood - definitive history can be obtained in about 50-60%.
Does rheumatic fever affect women or men more?
Women by a 2:1 to 3:1 ratio, usually acquired before 20, becomes evident 1-3 decades later
What is the underlying bacteria that causes rheumatic fever and thus rheumatic mitral stenosis?
Group A beta-hemolytic strep -> mimicry b/w strep antigens and heart tissue proteins -> antigen cross-reactivity + high inflam cytokine + low IL-4 -> auto-immune pancarditis -> valve leaflet (MV most common), endocardium, and myocardium damage -> commissural fusion, chordial fusion and shortening, leaflet fibrosis, calcifications
What are the physiologic adaptations of mitral stenosis?
Ventricular filling restriction -> LA pressure inc -> TV gradient increase during diastole -> … -> chronic and progressive stenosis -> inc PVR and pulm HTN
What are the valve area and transvalvular gradient consistent with mitral stenosis?
Diastolic pressure half time?
MVA < 1.5 cm^2 (MVA < 1 is very severe)
TVG >10 mm Hg
Other dx criteria: diastolic half-time >150 ms
Will cause elevated PASP >30
How is mitral transvalvular gradient dynamic as it relates to heart rate?
With increased HR -> dec duration of LV filling during diastole -> inc mean TVG and LA pressure.
This can create situations where the TVG is only significant (and thus symptomatic) during exercise.
Why is maintenance of sinus rhythm important for mitral stenosis patients?
Atrial contraction augments flow through the stenotic valve, thereby helping to sustain adequate forward cardiac output
Why does maintaining sinus rhythm become difficult for MS patients?
High LA pressure -> LA hypertrophy and dilation -> disorganized atrial muscle fibers -> abnormal conduction velocities -> nonhomogenous refractory periods -> inc automaticity or re-entry -> AF -> atrial thrombus and dec hemodynamic stability.
Eventually PASP >30.
MS = MVA < 1.5 or DP1/2t > 150 ms.
Describe the pathophysiology of pHTN in MS.
Passive transmission of high LA pressure (w/ severe enlargement of LA) -> PV HTN, pulm arteriole constriction -> pulm vasc obliterative changes -> PA systolic P >60 -> inc impedance to RV emptying -> RHF and TR.
Elevated PASP >30 is a hemodynamic consequence of severe MS.
How is frailty caused by MS?
“Cardiac cachexia” can be caused by the low CO, CHF, and lethargy associated w/ MS
Describe the TTE findings of rheumatic mitral stenosis
Reduced diastolic excursion of the leaflets, thickening or calcification of the valvular and subvalvular apparatus; M-mode can show thickening, reduced motion, parallel movement of the anterior and posterior leaflets during distole