Aiko Soda

Daily rhythms of left atrial pressure in beagle dogs with mitral valve regurgitation.

BACKGROUND Mitral valve regurgitation (MR) causes increased left atrial pressure (LAP) and is associated with occurrence of clinical signs. It will be useful to understand diurnal variations of LAP for the management of MR. HYPOTHESIS Circulatory parameters and diurnal rhythm are linked to clinical signs in cardiac diseases. LAP also exhibits a diurnal rhythm in dogs with MR. ANIMALS Five healthy Beagle dogs weighing 9.8-12.8 kg (3 males and 2 females; aged 2 years) were used. METHODS A radiotelemetry system for continuous measurement of LAP was used in this study. Rupture of the chordae tendineae was experimentally induced via left atriotomy, and a transmitter catheter was inserted into the left atrium. The body of the transmitter was implanted SC. After clinical condition was stabilized, the severity of MR was evaluated by echocardiography, and LAP was recorded for 72 consecutive hours for the analysis of diurnal variation. RESULTS Abrupt increases in LAP, which averaged 16.7 mmHg, were observed at feeding periods. In contrast, strong diurnal LAP variations were found, with a significant but slight increase in daytime LAP compared with nighttime LAP. CONCLUSIONS AND CLINICAL IMPORTANCE Diurnal LAP is characterized by a slight but significant nocturnal decrease and abrupt increases in response to excitation. The latter seemed to be more important considering the relationship with clinical manifestations. The clinical relevance of exercise restriction in the management of MR was acknowledged.

Efficacy of open patch-grafting under cardiopulmonary bypass for pulmonic stenosis in small dogs

OBJECTIVE To assess the efficacy of an open patch-graft technique under cardiopulmonary bypass (CPB) in small dogs. DESIGN AND METHODS A retrospective analysis of 10 dogs with pulmonic stenosis. Records between 1992 and 2002 were reviewed. The effect of surgical correction was evaluated and perioperative parameters were compared between survivors and non-survivors. RESULTS The postoperative pulmonary pressure gradient was reduced in all seven surviving patients. Mean +/- SE was 21.5 +/- 7.4 mmHg (range 3.0-54.2 mmHg) and 6/7 dogs were < 40 mmHg at 3 months postoperatively. Comparing the data between those patients that survived and those that did not, the preoperative pressure gradient (P = 0.04) and volume of the Glucose-Insulin-Kalium solution used (P = 0.001) were significantly higher in those that did not survive. CONCLUSION Open patch-grafting can be performed in small-breed dogs and decreased the pulmonary pressure gradient in survivors at 3 months postoperatively. However, this technique is more invasive than balloon valvuloplasty and should be used cautiously in severely stenosed patients.

Hydrodynamic characteristics of porcine aortic valves cross-linked with glutaraldehyde and polyepoxy compounds

Porcine aortic valve (AoF) tissues cross-linked with glutaraldehyde and epoxy compounds were reported to have high anticalcification properties, but their hydrodynamic characteristics have not been evaluated. The aim of the present study was to investigate the hydrodynamic differences between porcine AoFs, cross-linked with concomitant use of an epoxy compound and glutaraldehyde, at different fixation periods. The valves were mounted on a pulsatile flow circulation mimicking a left heart. The left atrial and left ventricular pressures and mitral and aortic flows were measured at every 0.002 seconds, and the hydrodynamic factor of the valves mounted on the mitral position was estimated. Effective orifice area and the regurgitation volume, which are used as indicators of valve efficiency, failed to detect significant differences due to glutaraldehyde fixation time. In addition, the pressure gradient across the bioprosthetic valve and the variation of mitral flow also had no significant differences. The flow circuit model of the present study was mimicking of a left heart. The evaluation of the mitral valvular function with different glutaraldehyde fixation times was accomplished by relating the pressure with the flow, and by estimating the time lag between valve motion and transvalvular flow.