B P8 C75 Mitral Stenosis Flashcards
RMS is now largely concentrated among the LMICs that are endemic for _____.
Group A Streptococcus (GAS) pharyngitis and ARF
The mechanism for valve damage in RMS is not clear but is thought to be ______ and involves both humoral and cellular immune mechanisms
Autoimmune response to GAS moieties that mimic valve antigens
_____ is most common in the Western world and is mainly mitral annular calcification (MAC) related, although MS after mitral valve interventions is increasingly seen in tertiary care centers
Degenerative MS (DMS)
The normal mitral valve area (MVA) is ≥_____ cm2
≥ 4.0 cm2
A gradient across the mitral valve starts to form with reduction in MVA to _____ cm2, considered mild MS, and symptoms begin to appear, initially with exercise.
Symptoms, more consistently develop at ≤ ____ cm2 and are associated with a 5 to 10 mm Hg gradient
2.0 cm2 - mild - gradient starts to form, symptoms begin to appear
≤1.5 cm2 - associated with 5-10 mm Hg gradient
Significant hemodynamic changes (gradients in excess of _____ mm Hg) and resting symptoms are common at MVA ≤_____ cm
> 10 mm Hg
< 1.0 cm2
Guidelines consider “severe” MS based on when symptoms occur and where intervention can improve them, and ≤_____ cm2 is the recommended threshold for this
1.5 cm2
MS due to a prosthetic valve is generally defined as resting mean valve gradient ≥ _____ mm Hg, peak mitral inflow velocity ≥ _____ msec, or effective orifice area ≤____ cm2.
MVG ≥ 5 mm Hg
Peak Mitral Inflow velocity ≥ 1.9 msec
EOA ≤ 2.0 cm2
Cardiac valve involvement in ARF starts with inflammation at the valve _____
Edges
The main abnormality in RMS is _____.
Fusion of the mitral leaflets in critical areas
* at their medial and lateral edges (commissural fusion), and the valve opening
* Narrowest at the valve tips
* Becomes a rigid structure that is oval or fish mouth shaped
RMS is characterized by _____ rather than just stiff valve leaflets and hence a relatively fixed orifice, and unlike AS, changes very little with varying hemodynamic conditions.
An increased LA pressure is then needed to maintain left ventricular (LV) filling and preserve cardiac output.
Commissural fusion
While MVA defines anatomic severity, it is the _____ that determines clinical symptoms and improvement after definitive therapies like percutaneous balloon mitral valvuloplasty or surgery
LA pressure
_____ is one of the most important factors in increasing LA pressures since it significantly reduces diastolic filling time and compromises forward flow, which is immediately seen as high mitral valve gradients and worsening symptoms.
Tachycardia
Atrial contraction helps overcome the resistance at the mitral valve level and preserve forward flow in MS—not surprisingly, the loss of atrial contraction and tachycardia during _____ can precipitate clinical worsening even in patients previously asymptomatic
AF
Since the gradient across the mitral valve increases as a square of the flow, small increases in the latter can have large effects on the gradient and its resulting symptoms, as seen in pregnancy, severe anemia, thyrotoxicosis, systemic infection, and other hyperdynamic states.
Chamber compliance (LA and to some extent, LV) also plays a role in development of symptoms, abnormal exercise hemodynamics, pulmonary hypertension (PAH), and degree of relief after relief of stenosis.
A newly recognized subset termed low gradient MS (MVA <____cm2, mean gradient <___ mm Hg, and _____) is now being recognized in the developed world and may account for a significant proportion of patients coming to BMV in some centers
MVA < 1.5 cm2
MVG < 10 mm Hg
Significant symptoms
Some patients with these hemodynamic findings—constituting 11% of BMV patients in one series12—appear to have a physiology akin to heart failure with preserved ejection fraction superimposed on MS and is characterized by older individuals with normal intrinsic LV contractility, decreased LV compliance, and high arterial afterload.
They respond suboptimally to BMV, highlighting that reduced LV compliance may explain symptoms that do not respond to treatment of MS alone.12
Backward transmission of high LA pressures results in ______ and ______; lung congestion explains exercise intolerance and dyspnea (and pulmonary edema in the most severe cases), and its relief, with diuretics or definitive MS treatment, is associated with immediate clinical benefit through reversing these changes
Pulmonary venous hypertension and increased lung water
Chronically elevated LA pressure results in ______ . This can improve symptoms for a short period before progressive MS overcomes these mechanisms
The development of ______ also ameliorates these symptoms but at the expense of right heart overload and possibly low cardiac output.
Prolonged elevation of LA pressure and LA remodeling can result in _____ that affects LA compliance. This may not be reversible after BMV, and low net AV compliance, which reflects the LA-LV as a unit, predicts both need for intervention and worse prognosis after BMV.
(1) Alveolar/interstitial thickening that limits alveolar edema
(2) Increased lymphatic drainage helps redistribute alveolar fluid
PAH
LA fibrosis
_____ are an early marker for LA dysfunction, can be seen in asymptomatic subjects with moderate MS, and are common in both RMS and DMS.
LA strain abnormalities
LA volume is increased and LA emptying fraction is reduced.
_______ is affected particularly in RMS and both reservoir strain (reflecting LA filling) and conduit strain (a marker for early diastolic emptying) are reduced, especially in patients with _____.
Abnormal _____ is associated with reduced functional capacity, predicts future AF, and identifies adverse prognosis in asymptomatic subjects with moderate MS.
Conduit strain - RMS
Reservoir + Conduit strain - MAC
Peak atrial longitudinal strain (PALS)
______, a more sensitive parameter for LV function, however, is commonly abnormal in RMS and improves rapidly after BMV.
LV deformation
Overt RV dysfunction occurs late in the course of MS and is often a consequence of _____.
PAH
Valve area in RMS decreases approximately _____ cm2 per year.
0.09 cm2/yr
Age, hemodynamic severity at diagnosis, and degree of valve deformity seem to predict progression.About a third show higher rate of progression, but this is not easily predictable from traditional clinical variables.
Recurrent episodes of ARF mediate faster progression in LMICs but this evolution can occur even without repeated episodes suggesting some role for other factors like hemodynamic damage and scarring.
_____ are an important trigger for definitive therapy and have strong prognostic value
Symptoms
Patients can first present with AF; almost _____% presented with an embolic episode in the past but early detection of AF in MS and aggressive use of oral anticoagulants (OACs) has markedly reduced this complication.
20%
_____, initially on exertion and then at rest, is the usual presentation in MS
Dyspnea
Transition to the symptomatic phase is often precipitated by _____ or conditions generating increased flow across the valve—AF and pregnancy commonly bring asymptomatic patients to attention in LMICs
Tachycardia
Stage A MS
- At risk for MS
- Mild valve doming during diastole
- Normal transmitral flow velocity
- No hemodynamic consequences
- No symptoms
Stage B MS
- Progressive MS
- Valve anatomy:
Rheumatic valve changes with commissural fusion and diastolic doming of mitral valve leaflets
Planimetered MVA >1.5 cm2 - Valve hemodynamics
Increased transmitral flow velocities MVA >1.5 cm2
Diastolic pressure half-time <150msec
*Hemodynamic consequences:
Mild to moderate LA enlargement
Normal pulmonary pressure at rest
- No symptoms
Stage C MS
- Asymptomatic severe MS
- Valve anatomy:
Rheumatic valve changes with commissural fusion and diastolic doming of mitral valve leaflets
Planimetered MVA ≤ 1.5 cm2 - Valve hemodynamics:
MVA ≤ 1.5cm2
Diastolic pressure half-time ≥150 msec - Hemodynamic consequences:
Severe LA enlargement Elevated PASP >50
mm Hg - No symptoms
Stage D MS
- Symptomatic severe MS
- Rheumatic valve changes with commissural fusion and diastolic doming of mitral valve leaflets
Planimetered MVA ≤ 1.5 cm2 - Valve hemodynamics:
MVA ≤ 1.5cm2
Diastolic pressure half-time ≥150 msec - Hemodynamic consequences:
Severe LA enlargement Elevated PASP >50
mm Hg - Symptoms
Decreased exercise tolerance
Exertional dyspnea
The dilated LA (______ syndrome—hoarseness due to compression of the recurrent laryngeal nerve) or pulmonary artery can cause pressure effects.
Ortner syndrome
PE findings due to the pathologic MV
- Loud S1 (and a tapping apex)
- Opening snap (OS)
- Mid-diastolic murmur with presystolic accentuation
PE findings due to the consequences of MS
- AF
- Pulmonary venous and arterial hypertension
- Tricuspid regurgitation (TR)
- Right heart failure
- In late stages, systemic hypoperfusion
The _____ is a classic feature of RMS and arises at the peak of a rapid and forced opening of the restricted mitral leaflet by high LA pressure. It denotes two important things
Opening snap
(1) its presence along with a loud S1 implies a pliable mitral valve that is likely to be a good candidate for BMV
(2) its timing helps in assessing severity of MS—a higher LA pressure opens the mitral valve earlier, and, therefore, time between aortic closure sound and mitral OS (A2- OS interval) is inversely proportional to the severity of MS
The S1 is often loud with a _____ mitral valve, but significant leaflet restriction (with fibrosis, calcification or subvalvular pathology) can decrease its intensity
Pliable
As with a loud S1, increasing calcification and rigidity of the body of the leaflets diminishes OS and might indicate ______ anatomy for percutaneous intervention.
Unfavorable anatomy
The murmur in MS is difficult to hear and needs practice and a quiet room for best detection; _____ can bring out the findings.
Tachycardia with mild exercise
It is a low pitched diastolic rumble, best heard at the apex with the _____ of the stethoscope while the patient is in the left lateral position.
Its onset follows the OS, but may be heard just during presystolic accentuation in mild MS and gradually increases in _____ with increasing severity of stenosis.
Bell
Length
The _____ of the murmur correlates with severity of MS but the intensity does not.
Length
A presystolic accentuation (coinciding with atrial contraction) is prominent unless the patient is in _____.
AF
Some murmurs may mimic MS—those from high flow across the mitral valve (severe MR, some shunts like ventricular septal defect, or patent ductus arteriosus with high Qp/Qs or other high flow conditions) can be differentiated from MS by their ______.
Clinical context
Short murmurs
Lack of an OS
Presence of an S3
S3 (which occurs later in diastole, is softer and not generally confused with OS) and S4 are not usually audible and their presence excludes severe MS
The Austin Flint murmur of aortic regurgitation (AR) usually does not have a ______ and there are clear signs of significant AR
Loud S1, OS, or presystolic accentuation
A _____ A2-OS interval followed by a ____ murmur starting earlier in _____ with prominent presystolic accentuation and signs of PAH or RV overload in a patient with limiting symptoms suggests severe MS.
Short A2-OS interval
Long murmur starting early in diastole with prominent presystolic accentuation
______ indicates a pliable valve that could be suitable for BMV.
Loud S1 and prominent OS
MVA is best assessed with _____ in all patients with RMS since it is the most accurate method if done correctly (tracing the inner edge at valve tips in mid-diastole of a completely seen, enface orifice of good image quality) and less subject to effect of changing loading conditions
Planimetry
Class I recommendations for intervention for RMS
In symptomatic patients (NYHA Class II, III, or IV) with severe rheumatic MS (mitral valve area ≤ 1.5 cm2, Stage D) and favorable valve morphology with less than moderate (2+) MR in the absence of LA thrombus. PMBC is recommended if it can be performed at a comprehensive valve center
In severely symptomatic patients (NYHA Class III or IV) with severe rheumatic MS (mitral valve area ≤ 1.5 cm2, Stage D) who (1) are not candidates for PMBC, (2) have failed a previous PMBC, (3) require other cardiac procedures, or (4) do not have access to PMBC, mitral valve surgery (repair, commissurotomy, or valve replacement) is indicated. (IB)
The main abnormality in DMS involves the _____ of the valve leaflets rather than the tips as in RMS and is unevenly distributed around the valve inflow.
Base of the valve leaflets
Early mitral filling is often preserved and late diastolic gradients can become minimal in beats with long RR intervals, unlike in RMS
In addition, comorbidities reduce LA compliance and increase LV stiffness, both of which can lead to elevated LA pressure despite smaller Doppler gradients across the mitral valve; it is sometimes difficult to be certain that MAC related mitral inflow obstruction rather than comorbidities is the dominant cause of symptoms.
A premature beat has less of an impact on LA pressures. Long RR intervals allow more complete LA emptying, and significantly lower LA pressure, and the gradient is appreciably ______ during diastasis, something that is not usually seen in severe rheumatic MS
Reduced
