RESUMEN
This report describes a case of accessory mitral valve in an elderly patient on maintenance hemodialysis. Transesophageal echocardiography revealed a mobile sac-like structure with size of 12 × 10 mm(2), which attached to the left ventricular surface of base of the anterior mitral valve leaflet. Mobile stick-like structure with diameter of 21 mm was extending from this sac-like structure toward the left ventricular outflow tract and had a floating free edge. Peak pressure gradient across the left ventricular outflow tract was 32 mmHg. There were no other congenital cardiac anomalies. No clinical findings suggestive of bacterial or nonbacterial vegetation were seen. Also other possibilities of mobile thrombus or calcification were unlikely. These abnormal structures were diagnosed as accessory mitral valve with rudimentary chordae.
RESUMEN
We developed a simple method to eliminate electrocardiogram (ECG) artifacts from electroencephalogram (EEG) records by using simultaneously recorded ECG data. The raw EEG data, the real EEG data and the ECG data were regarded as multi-dimensional vectors Ea, Er and C, respectively. Also, the ECG data, with reduced amplitude whose coefficient was denoted as 'k', were assumed to be overlapped on the real EEG. These assumptions introduced the equations [Ea = Er + k.C], [Er.C = 0] and finally [k = Ea. C/C.C]. This calculation method was implemented by a Macintosh computer using data exported from digital EEG recordings (sampled at 200 Hz with 16-bit resolution). In several subjects, sampling intervals of 5 or 10 seconds for calculation succeeded in eliminating ECG artifacts. However, regardless of the sampling interval, this elimination condition was not always efficient in several other subjects, including a brain-dead patient. It was suggested that the ECG data used were insufficient for the calculation, because only one hand-to-hand reference was used for simultaneous recording, as usual. This one ECG reference was able to express only one ECG projection. Then two other hand-to-foot references of ECG were added to the recordings, and the elimination procedure was performed using all of the simultaneously recorded ECG data at the three references. Consequently, elimination was much improved in most subjects, including the brain-dead patient. Our method may be useful for eliminating ECG artifacts without changing reference electrodes.