Biomedical subjects

H Ishitoya

Publications and source records attributed to H Ishitoya.

25 records · Page 2Linked to original sources

PubMed1994

[Relation between surgical outcome and preoperative end-systolic volume of the left ventricle in patients with regurgitant valvular heart disease].

The relation between the end-systolic volume index of the left ventricle (ESVI (ml/m2)) and the early and late results after valve replacement were reviewed in 249 patients with pure aortic regurgitation (AR) and 189 patients with pure mitral regurgitation (MR). The patients with AR were classified into 4 groups (A1-A4) and those with MR were classified into 3 groups (M1-M3) according to the ESVI. The ESVI, the number of patients (No of P), early mortality rate (EM) and the actuarial survival rate at 12 years after valve replacement (AS at 12 yr) in each group are shown in the following Table. [table: see text] The actuarial survival rate at 12 years after operation in A1 and A2 were significantly lower than that in A3 and A4. In 57% of the late deaths in A1 and A2 patients, the cause of the death was thought to be rhythm disturbance. In contrast, there were no differences in late survival among the three groups with MR (M1, M2 and M3). The minor axis of the left ventricle at end-diastole and at end-systole (Dd and Ds) and shortening fraction of the left minor axis (FS), evaluated by echocardiography, were normalized early after the operation in A1 patients only. The Dd, Ds and FS in A2 and A3 returned to normal late after the operation. However, in A4, these parameters still remained abnormal. Thus, patients with a deteriorated left ventricle can survive the operation. However, the long-term results in patients with AR with ESVI more than 150 ml/m2 were unsatisfactory.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve Insufficiency↗

PubMed1994

[Curative report of post sternotomy mediastinitis due to bacterofungal infection].

We describe a 72-year-old patient with mediastinitis caused by Methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans after median sternotomy who was successfully treated with wound closure with pectoral musculocutaneous flap and closed continuous mediastinal irrigation. The irrigation device consisted of two pairs of irrigation and suction tubes which placed upper and lower half of mediastinum respectively, in which high rate irrigation technique (200 ml/h) was employed using 0.01% of Vancomycin hydrochloride as a base agent and additional 0.1% of Povidone-iodine in early phase and 0.01% of Fluconazole in late phase. After 12-days irrigation, the drainage culture turned negative and the wound was healed and tomographically granulated. High rate irrigation with sufficient concentration of antimicrobial agents selected according to each organism sensitivity could eliminate redundant irrigation and contribute to avoid antimicrobial toxication. We experienced also another four cases (two caused by MRSA, two caused by Serratia liquefaciens) treated successfully with this technique. These results led us to believe that continuous mediastinal irrigation technique could be carried out with safe and effectiveness so far as high rate irrigation with low concentration of Povidone-iodine is employed.

Aged↗

PubMed1992

[A case of sliding commissuroplasty for the chordal rupture in the paracommissural area].

A 67-year-old female patient underwent mitral valvuloplasty for mitral regurgitation due to the chordal rupture at the posterior commissure. Sliding commissuroplasty was made to avoid large annular plication. Carpentier's prosthetic ring (30 mm) was sutured to remodel the annulus and to reinforce repair. Postoperative Left ventriculogram revealed no regurgitation. Sliding commissuroplasty is effective for mitral regurgitation due to commissural chordal rupture.

Aged↗

PubMed1992

[A case report of ruptured aneurysm of the sinus Valsalva resulted in tricuspid valve endocarditis].

A case of a 42-year-old man with ruptured aneurysm of the sinus Valsalva resulted in tricuspid valve endocarditis was reported. The aneurysm originating from the right sinus Valsalva ruptured into the right atrium, which caused tricuspid valve endocarditis. The aneurysm was closed through right atrial approach. A part of the septal leaflet of tricuspid valve including vegetation was resected and repaired.

Adult↗

PubMedDate not supplied

Effect of additional intraaortic balloon support during weaning from a left ventricular assist system.

A safe and reliable method of weaning from a left ventricular assist system (LVAS) is necessary for successful circulatory support in patients with marginal heart failure. The purpose of this study is to assess the effect of additional intraaortic balloon (IAB) support during weaning from an LVAS by means of the LV pressure-volume relationship. A pneumatic LVAS with a sac-type blood pump was implanted in six adult mongrel dogs weighing 14 to 20 kg. All dogs had a drainage cannula placed in the left atrium and an outflow conduit in the ascending aorta. Hemodynamic parameters, pulmonary arterial flow, and pump output were monitored. An IAB was inserted through the groin. A conductance catheter and microtip manometer were inserted into the LV cavity. As a combination driving mode, LVAS ejection in the early diastolic phase and IAB inflation in the late diastolic phase were applied. After evaluation of baseline LV function, the pressure-volume relationship was repeatedly measured during change of driving modes as isolated LVAS, LVAS + IAB (1:1), LVAS + IAB (2:1), and isolated IAB supports. Finally, LV failure was introduced by stepwise ligation of left coronary arteries, and the LV pressure-volume relationship was measured in each driving mode. Under normal conditions, the pressure-volume loop showed no significant change among the four driving modes. In contrast, the LV pressure-volume relationship significantly improved according to the degree of additional IAB support on LVAS assistance under the condition of LV failure. These results suggest that additional IAB support might improve LV energy during weaning from an LVAS.

Animals↗

PubMedDate not supplied

Operating point control system for a continuous flow artificial heart: in vitro study.

We proposed and developed a practical and effective servo control system for rotary blood pumps. A rotary blood pump for assisting the failing natural heart should be operated only in physiologically acceptable conditions. The operation of a rotary blood pump is based on the rotational speed of the impeller and pressure head. If the pump flow and the pressure head are set within an acceptable range, the driving condition is deemed normal condition, and this control system maintains the preset operating point by applying proportional and detective control (PD control). If the pump flow or pressure head is outside the acceptable range, the driving condition is determined to be abnormal condition, and this system operates the pump in a recovery fashion. If the driving condition is kept under abnormal conditions of sudden decrease of the flow, the condition is termed a suction condition. The controller releases the pump from the suction condition and later returns it to the normal condition. In this study, we evaluated these servo control modes of the centrifugal pump and confirmed whether the performance of this proposed operating point control system was practical.

Algorithms↗

PubMedDate not supplied

Evaluation of floating impeller phenomena in a gyro centrifugal pump.

The Gyro centrifugal pump, developed as a totally implantable artificial heart, was designed with a free impeller in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet balance) to prevent thrombus formation or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller is lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proven by observation of the impeller behavior by means of a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and the rotational speed of the impeller. To keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving conditions of right and left pumps, the magnet-magnet coupling distance was altered by a spacer that was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist) by changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller revolution. This is called "the dynamic revolutions per minute suspension."

Centrifugation↗