Chapter 42

    It is a rather common situation involving the mitral valve and producing a rather typical auscultatory syndrome, as described by J.B. Barlow in 1968.
    This syndrome is frequently sporadic but many familiar cases were reported and a dominant Mendelian inheritance seems to be prevalent.
    Anatomically, the billowing occurs more often in the posterior mitral leaflet with dilation of the valve and many times prolapse and consequently blood regurgitation during late systole. Cases where billowing is present in both leaflets are probably not uncommon. Rarely, the syndrome can be seen in the tricuspid valve.
    Microscopically, a non-specific myxomatous degeneration seems to be responsible for the pathology. This mucoid degeneration is localized in the mitral valve and does not affect other structures as the aorta or myocardium.
    The billowing of the mitral valve should be distinguished from similar situations as seen in:

Marfan's syndrome and Ehler-Danlos' syndrome. Idiopathic hypertrophy subaortic stenosis. Mitral insufficiency due to RHD and trauma. Mitral insufficiency in papillary muscle dysfunction. Floppy mitral valve syndrome, which is more progressive and severe.

    Temporary mitral valve prolapse secondary to myocardial trauma, contusion of the papillary muscle or subvalvular apparatus is not unusual.

CLINICAL PICTURE AND PHYSICAL FINDINGS

    The condition is rare in infants and usually appears in adolescents and young adults. The majority of these patients are totally asymptomatic, others will present with chest pain, probably associated with abnormal papillary muscle stress. The severity of the pain does not correlate with the severity of the prolapse. Many times the symptoms are the ones of typical angina pectoris with close relation to physical exertion. Many times, however, no good correlation with activity or resting is founded.
    Palpitations are not uncommon and probably correlate with ventricular arrhythmia and less common with atrial arrhythmias.
    There are rare cases of sudden death reported with a possible relation to underline prolapsing of the mitral valve and arrhythmias induced by this condition.
    Most of the time the prolapse is merely an ausculatory syndrome characterized by:

1. Systolic click, sharp and easily audible. Some other times is rather dull - the click can occur in early, middle or late systole.
2. Murmur of mitral regurgitation, not always present. Usually is a late systolic apical murmur.
3. Standing may induce early appearance of both the systolic click and the murmur.
       In the standing position, not rarely the murmur may turn panysystolic.
4. Many times the auscultatory syndrome is incomplete and click with no murmur or vice versa can be seen. However, the systolic murmur or click can be easily induced by the standing position.
5. Silent mitral billowing can occur but in this case, isometric exercise, Valsalva maneuver and different vasoactive drugs can make a click or a murmur appear for the first time.
6. Atypical presentation as a pansystolic murmur can be seen. In rare cases typical mitral opening snap has been recorded.

ROENTGENOGRAM

    The roentgenogram is usually normal unless gross regurgitation across the mitral valve appears.

ELECTROCARDIOGRAM

    The electrocardiogram, when abnormal, reveals inverted T waves in leads 11,111 and AVF. Sometimes ST segment depression can be noted in the same leads. Positive Treadmill Test for ischemia with normal coronaries is not uncommon.
    As previously noted, ventricular and supraventricular arrthymias are not unusual in the form of single isolated premature contractions, atrial fibrillation, atrial flutter and in rare cases, ventricular tachycardia and ventricular fibrillation.

ECHOCARDIOGRAPHY

    Echocardiography is of tremendous help in this syndrome in demonstrating the abnormal pattern of mitral valve motion typical of this pathology.
    A good sonographic diagnosis is however, synonymous of expertise, and misleading conclusions result from a mediocre echocardiographer.
    Echoes of consequent mechanics recognized. both anterior and posterior leaflets can be seen with their pattern of movement. Left atrial size, ventricular and muscular subvalvular apparatus can also be recognized.

LEFT VENTRICULAR ANGIOGRAPHY

    Left ventricular angiography in both oblique projections will closely demonstrate the posterior ballooning of the mitral leaflet during systole.
    RAO projection is the optimal position for evaluation of mitral valve regurgitation and ventricular contractions.
    Catheterization and angiography, however, are usually not necessary for a final diagnosis since the advent of echocardiography.