Mitral Valve Prolapse Revisited
A 75-year-old man was admitted with abrupt onset of dyspnea during sleep. On examination, his blood pressure was 222/165 mm Hg, pulse was 160 bpm, and oxygen saturation was 75% while breathing ambient air. Heart sounds were difficult to assess because of coarse crackles and his moaning. There was no edema in the extremities. An ECG showed sinus tachycardia with a QRS duration of 111 milliseconds, and a chest radiograph showed pulmonary edema without cardiomegaly. A presumed diagnosis of acute heart failure was made, and isosorbide dinitrate was administered intravenously with supplemental oxygen via a face mask. Cardiac auscultation after stabilization of vital signs showed a holosystolic murmur at the apex and an early systolic click at the left sternal border. Mitral regurgitation resulting from mitral valve prolapse (MVP) was most likely but was not confirmed by transthoracic echocardiography because of a lack of definitive evidence (Figure 1). Of note, another extra sound during early diastole was heard best at the third left sternal border.
A phonocardiogram performed 4 days after admission with the MES-1000 (Fukuda-Denshi Co, Tokyo, Japan) showed a holosystolic murmur at the apex and an early systolic click at the third sternal border (Figure 2 and Audio Files I and II in the online-only Data Supplement, respectively). An early diastolic heart sound with an interval of 110 to 130 milliseconds from the onset of the preceding second heart was recorded at the third left sternal border. Prolapse of A2 and A3 scallops of the mitral valve caused by ruptured chordae tendineae was later confirmed on transesophageal echocardiography (Figure 3 and Movie I in the online-only Data Supplement). The early systolic click and early diastolic extra sound had gradually diminished and almost disappeared in 2 weeks, as shown in a follow-up phonocardiogram (Figure 4). Because the patient refused to undergo surgical treatment of the mitral valve, he was discharged with azilsartan, amlodipine, and trichlormethiazide and was lost to follow-up after the first visit.
One interesting finding in our case is the additional heart sound during early diastole. The differential diagnoses include a mitral opening sound, a pericardial knock sound, and a third heart sound (S3). Given the clinical and echocardiographic findings, S3 is most likely because severe mitral regurgitation is known to be associated with S3. This condition, however, is implausible because the extra heart sound in the present case was obscure at the apex and was composed predominantly of high frequency. We may safely consider that the early diastolic additional sound was associated with MVP, although this is not widely appreciated. In 1976, Bonner et al1 reported a case of MVP with a midsystolic click, a late systolic murmur, and a striking early diastolic sound. In a study of 150 patients with MVP by Wei and Fortuin,2 8 patients (5.3%) had an early diastolic sound that was high-pitched, was best heard at the left sternal border, and coincided with the time when the prolapsed mitral leaflet recoapted with the unprolapsed mitral leaflet after returning from the left atrium.
Another interesting finding is the changes in the amplitude of the systolic click and diastolic extra sound over the clinical course. A systolic click associated with MVP is thought to be produced by a sudden flip of a prolapsed piece of the mitral leaflet during systole3 and is reported to be affected by various factors.4 The gradual disappearance of systolic clicks is reasonable in our case because the hemodynamic status, for example, blood pressure and heart rate, had improved with treatment. The present case indicates that not only a systolic click but also an extra diastolic sound associated with MVP or “diastolic click” can be modified in response to clinical conditions. Given that the final diagnosis of mitral regurgitation caused by MVP was delayed because of inadequate information on transthoracic echocardiography, the present case highlights the importance of auscultation even in the era of advanced imaging techniques.
We thank Drs Hiroki Sugihara and Hiroshi Katsume for thoughtful comments on the manuscript.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.115.020273/-/DC1.
- © 2016 American Heart Association, Inc.