Psychiatric symptoms in renal transplant patients in relation to alexithymia.
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Adult↗
Biomedical subjects
T Komoda
Publications and source records attributed to T Komoda.
Study of anatomic constraints using three dimensionally reconstructed images for total artificial heart implantation.
The authors established a method of clarifying the three dimensional interrelationship among the mitral and tricuspid annuli, ascending aorta, main pulmonary artery, diaphragmatic surface of the heart (DS), and anterior thoracic wall, using four chamber view magnetic resonance imaging. This method was applied to measuring the parameters that restrict the size and shape of a total artificial heart (TAH) from three dimensional reconstructed images of six normal subjects. Assuming that the TAH is implanted on the diaphragm, which corresponds to DS, the width of the TAH is restricted to 7.6 cm, the transverse dimension of the cardiac base (D-B), and the height to 7.8 cm, the dimension from the DS to the center of the pulmonic annulus (DS-P1). Depth is restricted by the longitudinal dimension of the left ventricle projected on the DS (D-L). While D-L in early systole is 9.7 mm, in late systole D-L is reduced to 7.6 cm. The angle (DS) (AW) is 65.7 degrees; this is the angle between the DS and anterior thoracic wall that restricts the shape of the TAH. While these data in normal subjects may be useful for TAH implantation, in the patient with acute cardiac failure, further study of patients with chronic cardiac failure is necessary.
Adult↗
The inflexible mitral annulus after valve prosthesis. Inherent risk of dynamic left ventricular outflow tract obstruction.
Although chordal preserving mitral valve replacement is beneficial to cardiac function, the loss of flexibility of the annulus and consequent translational motion of the valve prosthesis during systole may cause potential left ventricular outflow tract (LVOT) obstruction after surgery. The extent of the flexibility of the mitral valve annulus (MVA) necessary for the prosthetic valve to prevent potential LVOT obstruction was determined. The three dimensional images of the MVA at 0, 100, 200, and 300 msec delay from the electrocardiogram R wave were reconstructed from cine-mode magnetic resonance images in eight normal subjects. In the lateral view of the MVA, the dorsal flexion angle (DFA) was defined. This angle implies the extent of the flexion of the anterior half of the MVA in relation to the posterior half. The data (mean +/- SD) for the DFA were 31.7 +/- 5.4 degrees (0 msec), 36.4 +/- 4.5 degrees (100 msec), 39.0 +/- 3.8 degrees (200 msec), and 43.6 +/- 2.6 degrees (300 msec), whereas the systolic increase in DFA was 11.9 +/- 3.2 degrees. The flexibility observed in normal mitral annuli is relevant to prosthetic mitral valves.
Adult↗
The relationship between the mitral annulus and left ventricular outflow tract.
Mitral annular inflexibility due to rigid prostheses (ring or valve) has long been considered to contribute to the mechanism of dynamic left ventricular outflow tract (LVOT) obstruction after mitral repair or replacement. In clarifying the geometric relationship between LVOT orifice and mitral valve annulus (MVA) in eight normal subjects, the authors have endeavored to show how that a rigid mitral prosthesis might obstruct the LVOT based on the assumption that any rigid prosthesis necessarily follows the motion of the posterior half of the MVA (MVApost) in the course of every heart beat. During systole, the relationship between the MVApost and the approximated plane of the LVOT orifice was constant. However, with the respect to the relationship between the LVOT orifice and the approximated plane of the MVApost (PI-MVApost), the intersection between the two shifted toward the apex during systole. Assuming the prosthesis is aligned on the MVApost with the same orientation as the PI-MvApost, this shift implies a reduction in the effective size of the LVOT orifice due to the prosthesis. The calculated obstruction rate was 24.9% (0 ms), 30.9% (100 ms), 35.5% (200 ms), and 45.4% (300 ms). These results indicate the importance of maintaining the flexibility of the MVA after mitral valve surgery.
Adult↗
Effects of prosthetic valve placement on mitral annular dynamics and the left ventricular base.
Insertion of a rigid mitral prosthesis impairs the function of the mitral annulus and induces systolic narrowing of the left ventricular outflow tract (LVOT). To study this mechanism, we investigated dynamic changes in the left ventricular (LV) base, which consists of the mitral annulus and LVOT orifice. In seven patients with mechanical mitral valve prostheses and eight normal subjects, the image of the LV base was reconstructed three-dimensionally and its dynamic change during systole was studied. In the patients, the rigid prosthetic valve (=mitral annulus) tilted toward the left ventricle with a hinge point at the posterior mitral annulus during systole. The left ventricular base exhibited contraction, but the size of the prosthetic valve was constant. As a consequence, the prosthetic valve occupied more of the left ventricular base, which resulted in narrowing of the LVOT. In the normal subjects, the mitral annulus did not interfere with the region of the LVOT orifice during systole as the mitral annulus underwent both dorsiflexion and contraction. Thus, fixation of the mitral annulus induces an anti-physiologic motion of the annulus. Conscious preservation of annular flexibility in mitral valve surgery is important in avoiding potential dynamic LVOT obstruction.
Adult↗
Mitral annular flexibility.
An analysis of three-dimensional movement of the mitral valve annulus (MVA) may address the question of geometrical change after mitral valve repair to preserve mitral annular function. Conventionally, annular contraction has been studied for this purpose. We investigated this geometrical change occurring in the anterior half of the MVA and discuss its clinical significance. Three-dimensional images of the MVA during systole were reconstructed from magnetic resonance images of eight normal subjects. The posterior half of the MVA exhibited translational motion. We assume that this portion, exhibiting translational motion as well as contraction, purely follows the motion of the left ventricular contraction. Compensating for the discrepancy between the motion of the aortic root and that of the posterior half of the MVA, the anterior half exhibited a flexible change in shape during systole, thus maintaining a sufficient left ventricular outflow tract (LVOT). The increase in the extent of displacement of the anterior MVA from the posterior half of the MVA during systole, which was 3.6 +/- 1.0 mm (mean +/- SD), indicates the annular flexibility. The preservation of annular flexibility may prevent LVOT obstruction. Further geometrical analysis of patients after mitral repair will clarify annular function as presented in this article.
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Reconstructed image of the human heart based on magnetic resonance images for total artificial heart implantation.
Parameters used to develop a three-dimensional reconstructed image of the remaining heart after total artificial heart implantation (i.e., for the mitral and tricuspid annuli, ascending aorta (AO), and pulmonary artery [PA]) were calculated based on reconstructed images from data obtained from four magnetic resonance (MR) image views: 1) transverse, 2) coronal, 3) left ventricular long axis (LAX), and 4) four chamber view (FCV). The values obtained were compared with those obtained from silicone models of the same hearts. It was found that, of the four MR image views, LAX and FCV provided the greatest numbers of points reflecting annular contour that were useful in reconstruction of the atrioventricular (AV) annuli, and the highest percentages of segmented outline-connecting points less than 1 cm apart for the total outline. The AV annuli were sliced in the least slice time using FCV imaging. The authors applied FCV MR imaging to a beating heart to reconstruct the AV annuli and obtained accurate results. To quantify more accurately the data for the axis directions of AO and PA, research to establish a new orientation on the thorax is in progress.
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The three-dimensional relationships between mitral and tricuspid valvular annuli for total artificial heart implantation.
The three-dimensional relationship between the mitral valvular annulus (MVA) and tricuspid valvular annulus (TVA) was studied in 32 cadaver hearts. It was found that when the distance from the center of the MVA and TVA (D-G) were standardized and when MVA and TVA were overlapped by matching their centers, MVA was located in the fan shaped region in the lateral view of the TVA and pointed toward the orifice of the coronary sinus. D-G was correlated with the volume of the space occupied by both ventricles. When the value of D-G was standardized, TVA remains free to change its shape and orientation toward either the cranial or caudal direction.
Aged↗
A pulsatile cardiopulmonary bypass system that prevents negative pressure at the membrane oxygenator.
Negative pressure is a problem in pulsatile cardiopulmonary bypass (CPB). To avoid this, the authors designed a pulsatile CPB system containing a Sarns centrifugal pump (CP) and a Univox membrane oxygenator, in which the inertial flow is not obstructed by the CP. In both an in vitro study and a clinical study, negative pressure was not observed in the arterial line of the CPB circuit when this system was used. When a roller pump (RP) was used, however, instead of a CP, negative pressure did occur. In a clinical study using this system, mean pulse pressure was 36 mmHg and hemolysis, expressed as the rate of rise in plasma free hemoglobin from 10 to 70 min of CPB, was 26.2 mg/dl/hr, which did not exceed that seen with a pulsatile CPB using an RP instead of a CP. The hemolysis seen in the study caused no clinical problems. Thus, pulsatile CPB using a CP and Univox membrane oxygenator should be considered for clinical use to prevent the occurrence of negative pressure.
Cardiopulmonary Bypass↗
Dynamic change in the left ventricular base with or without a rigid mitral valve prosthesis.
To evaluate the narrowing of the left ventricular outflow tract (LVOT) during systole caused by a rigid mitral prosthesis, the geometric relationship between the prosthesis (or the mitral annulus) and the left ventricular base (LVB) was studied in five patients with mechanical mitral valve prostheses and eight normal subjects. The images of the mitral valve annulus (MVA) and the LVOT orifice reconstructed in three dimensions were projected on the plane of the LV base. Calculating the areas of these projected images (i.e., those for MVA [Sm], LVOT orifice [So], the LVB [Sb; Sb = Sm + So]), the MVA-LVB ratio (Sm/Sb) was determined. In the normal subject, the MVA-LVB ratio was nearly constant during systole (59 +/- 5% at 0 msec and 62 +/- 7% at 300 msec, respectively), whereas in the patients with prostheses, the ratio increased from 61 +/- 4% (0 msec) to 69 +/- 4% (300 msec). The increase in MVA-LVB ratio reduces the proportionate share of LVOT orifice in relation to the total LVB. The ideal mitral valve prosthesis should be flexible at the annulus to attain good performance in LVB dynamics.
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