CHAPTER 11: Mitral Regurgitation

PRIMARY MITRAL REGURGITATION

• Definition: Mitral valve apparatus is directly affected.

• Examples: Prolapse, flail leaflet, endocarditis.

• The Carpentier classification is useful for understanding etiology as well as therapeutic approaches.

  • - Type I: Normal leaflet size and motion, with the mitral regurgitation due to leaflet perforation or congenital clefts.

  • - Type II: Excessive leaflet motion with prolapse or flail leaflets.

  • - Type IIIa: Leaflet restriction in diastole, most commonly seen in rheumatic disease.

Source

• El Sabbagh A, Reddy YNV, Nishimura RA. Mitral Valve Regurgitation in the contemporary era: insights into diagnosis, management, and future directions. JACC Cardiovasc Imaging. 2018;11:628–643.

SECONDARY OR FUNCTIONAL MITRAL REGURGITATION

• Definition: The actual cause of the mitral regurgitation resides in the ventricle (not in the valve).

  • - Mitral leaflets and chordae are structurally normal.

  • - There is an imbalance between closing and tethering forces on the valve.

  • - It is caused by alterations in LV geometry.

• Examples: mitral annular dilatation due to dilated cardiomyopathy, dilated left atrium, chronic atrial fibrillation.

• As the mitral annulus dilates, the coaptive surface decreases (less and less of the leaflet tips are touching).

• Apical tethering can be measured as tenting area (performed in mid-systole when the area is at its smallest).

• Leaflet tethering is often asymmetric in ischemic cardiomyopathies.

• In these cases of unbalanced tethering due to regional wall motion abnormalities:

  • - The mitral regurgitation color flow jet is directed away from the relatively prolapsing leaflet.

  • - It is directed toward the relatively restricted leaflet.

  • - Initially left ventricular function becomes hyperdynamic.

  • - Global longitudinal strain may detect subtle left ventricular dysfunction.

Source

• Asgar AW, Mack MJ, Stone GW. Secondary mitral regurgitation in heart failure: pathophysiology, prognosis, and therapeutic considerations. J Am Coll Cardiol. 2015;65:1231–1248.

COLOR FLOW IN MITRAL REGURGITATION

• Jet area depicts blood flow velocities. This is not blood volume. It is a spatial display of velocities.

• Simply increasing left ventricular systolic “driving” pressure will increase the jet area with the same regurgitant orifice.

• Entrainment: A central mitral regurgitation jet will “pull in” (entrain) innocent bystander red blood cells that are already in the left atrium, exaggerating the apparent degree of regurgitation on color flow. When subjectively estimating the degree of regurgitation, one may want to “mentally downgrade” the severity.

• Coanda: An impinging eccentric mitral regurgitation jet creates the opposite dilemma: It may underrepresent the true severity of the regurgitation.

VENA CONTRACTA TECHNIQUE

• The transducer should be tilted so that PISA, vena contracta, and jet area can be identified.

• Zoom mode is preferred.

• Color flow sector should be kept to a minimum to optimize resolution.

MITRAL VALVE PROLAPSE

• One or both leaflets buckle back into the left atrium, characteristically in mid- to late systole. ...