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Biomedical subjects

Shunei Saito

Publications and source records attributed to Shunei Saito.

8 recordsLinked to original sources
PubMed2006

Mitral valve motion assessed by high-speed video camera in isolated swine heart.

OBJECTIVE: We have recently reported our isolated and working swine heart model that examines the valve motion precisely by a high-speed digital video camera system. Using this modality, the present study aimed (1) to delineate the motion of the mitral leaflets, chords and annulus throughout the cardiac cycle, and (2) to elucidate the influence of alterations in loading conditions on leaflet excursion. METHODS: The valve motion of five isolated and working swine hearts was observed by an endoscope recording the images at 250 frames per second. Modified Krebs-Ringer solution was used as the sole perfusate. The images were obtained in hearts 30 min after reperfusion, changing the left atrial pressure as 4, 8, and 12 mmHg. RESULTS: The motion of the mitral valve in the vicinity of diastole was considered to be well understood by dividing the entire sequence into five stages: 'decoaptation,' 'E excursion,' 'diastasis,' 'A excursion,' and 'coaptation.' Initial separation occurred at both sides of the central tips of the leaflets. The leading edges always followed the mid-portion of the rough zone during opening and closing. The 'strut' second-order chords retained their tension throughout the cardiac cycle and played the role as rotary shafts of the other branching chords. The first-order chords lost their tension during opening, suggesting they mainly are involved in valve competence. Annular constriction occurred coincident with atrial contraction. An increase in preload made the isovolumic relaxation and contraction times shorter. The leaflets opened faster in the rapid-filling phase, whereas they required more time for opening and closing in the atrial-filling phase. CONCLUSIONS: The present study revealed the integrated movement of the mitral leaflets, chords and annulus, as well as the impact of altered preload.

Animals↗
PubMed2006

Returning reservoir blood to right atrium during extracorporeal circulation for descending aortic surgery.

We report our techniques on conducting a closed-circuit femoral-femoral bypass during descending aortic surgery by which collected blood can be easily returned into the right atrium. The main circuit was composed of a centrifugal pump, an artificial membrane lung, and a filter. A reservoir with a roller pump was connected to the main circuit via a filter. Extracorporeal circulation was established by right atrial drainage via the femoral vein and femoral arterial return. On aortic cross-clamping, systemic blood pressure was controlled by activating the roller pump in reverse rotation and shifting the body blood into the reservoir temporarily. For a small amount of bleeding after aortotomy, the reservoir blood was returned via the femoral artery by activating the roller pump in normal rotation. When a large amount of bleeding was present making the systemic blood pressure fall, the main circuit was clamped just distal to the centrifugal pump and reservoir blood was directly returned to the right atrium to maintain systemic pressure. Confirming that bleeding was reduced, the clamp distal to the centrifugal pump was gradually released and blood was delivered to both the right atrium and the femoral artery. We believe that our system is a highly beneficial modality.

Aged↗
PubMed2006

Infective endocarditis with an aortic periannular abscess extending along the right coronary artery.

A 50-year-old male underwent surgery for infective aortic valve endocarditis, which had been refractory to medical treatment. The valve was bicuspid, and involvement of the annular and subannular structures was recognized. A large suppurative discharge was obtained on incising this portion. Although there was no interventricular shunt, the abscess cavity was revealed to extend through the epicardial surface of the right atrioventricular groove. Following extensive debridement and irrigation, the defect was closed by an autologous pericardial patch. A 23 mm mechanical valve was implanted placing some of the stitches deep into the muscular interventricular septum. Infection was controlled by six-week administration of cefazolin sodium and gentamicin sulfate, and the patient survived.

Abscess↗
PubMed2005

Surgery for calcific aortic root stenosis in homozygous familial hypercholesterolemia.

A 35-year-old female with homozygous familial hyperlipidemia (IIa) was referred to our hospital for an operation against supravalvular and valvular aortic stenosis. She had been treated with low-density lipoprotein apheresis for 20 years, and total cholesterol ranged between 200 and 400 mg/dl under this treatment. She had undergone percutaneous coronary intervention for ostial stenosis of the right coronary artery three times since the age of 19. Unenhanced three-dimensional computed tomography showed supravalvular stenosis, funnelling and heavily calcified aorta. An operation was performed under deep hypothermic circulatory arrest without aortic cross clamping. After the ascending aorta had been replaced with a one-branched vascular graft, arterial perfusion was resumed. The stenosed ascending aorta was resected at the sinotubular junction. Because the aortic root was still extremely small, the noncoronary sinus and the commissure between left and right coronary cusp were incised, and the aortic root was enlarged with linguiform vascular-graft patches. A 21-mm mechanical valve was implanted. The postoperative course was uneventful.

Adult↗
PubMed2005

Does antiphospholipid antibody syndrome affect bioprosthetic heart valve? Midterm echocardiographic report.

Cardiovascular involvements in antiphospholipid antibody syndrome have been recognized as a major complication of this disease. Furthermore, some papers report bioprosthetic heart valve also seems to be affected. A 32-year-old female with aortic regurgitation presented to our hospital. Further examination revealed high titer of anticardiolipin beta 2 glycoprotein 1 antibody, and she was diagnosed as having primary antiphospholipid antibody syndrome since the patient failed to match the criteria of systemic lupus erythematosus. Cardiopulmonary bypass was uneventfully conducted under systemic heparinization of usual dosage. Administration of warfarin sodium was started on the third postoperative day, and international normalized ratio was controlled from 2.0 to 2.5. On echocardiographic examination at 1 month, mean systolic gradient was 17 mmHg. Although transesophageal echocardiography at 2 years after surgery revealed no sign of valvular destruction or sclerosis, transaortic gradient had increased to 26 mmHg. Bioprosthetic stenosis was suspected probably due to pannus formation and the patient may have to undergo another valve replacement in the near future.

Adult↗
PubMed2005

Pressure-volume relationship in isolated working heart with crystalloid perfusate in swine and imaging the valve motion.

OBJECTIVE: It is widely accepted that both valve and cardiac functions are closely correlated. In order to investigate the relationship between the valve and cardiac functions, we developed a model of an isolated working heart with crystalloid perfusate in swine. We investigated the feasibility of this model to evaluate the precise left ventricular function using the pressure-volume relationship and metabolic measurement. Another objective was as a trial for the imaging and analysis of valvular interventions with a high-speed digital camera on this model. METHODS: Six isolated working hearts were subjected in the pressure-volume study, and additional three hearts were used in the valve imaging study. Measurement of the pressure-volume relationship was undertaken in situ before the heart was removed, and on the working heart mode during the initial 30 min as the baseline, and at every 60 min. Lactate levels were measured at every stage in the working heart mode. Mitral valve interventions were performed in three hearts, and valve motions were observed by a high-speed digital camera via the left ventricle. RESULTS: The end-systolic elastance maintained a baseline level (5.17+/-2.25) until 180 min and decreased at 240 min (3.97+/-1.97, NS) and 300 min (2.85+/-1.29, P<0.01) of the working heart mode as compared with baseline. The Tau maintained a constant level until 180 min and increased at 240 min (62.2+/-13.3, NS) and 300 min (85.5+/-43.4, P<0.05) as compared with baseline (50.3+/-13.6). The slope of the end-diastolic pressure-volume relationship gradually increased with no significance until 180 min and increased significantly (0.147+/-0.066, P<0.01 vs 0.067+/-0.041 at baseline). Lactate increased accumulatively. The total heart energy was reduced from the initial phase of the working heart mode. The valves were well captured by the high-speed digital camera. CONCLUSIONS: The systolic and diastolic functions of an isolated heart were preserved at an acceptable level for 180 min. The practical reliability of the swine working heart model was demonstrated. This model will be used reliably for the investigation of the interaction of valve and cardiac functions.

Animals↗
PubMed2004

Convenient training method for aortic cannulation: glove- and-peel method.

Aortic cannulation is a difficult technique for young cardiovascular surgeons. A convenient training method for this procedure is introduced in this paper. After two gloves are worn on a hand, they are removed together, then a piece of mandarin-orange peel is inserted between the gloves. The inner glove is filled with water and the mouth of the inflated gloves is securely tied with a strong ligature. Then this "glove balloon" is set inside a container to stabilize it. Purse-string stitches are placed on the orange peel. After the center of the purse string is incised with a number 11 blade, a cannula is introduced. This "glove-and-peel method" will help young cardiovascular surgeons to become accustomed to aortic cannulation.

Aorta↗