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Biomedical subjects

K Kawachi

Publications and source records attributed to K Kawachi.

At least 163 records · Page 9Linked to original sources
PubMed1989

[Surgical treatment of postinfarction ventricular septal perforation--the difference between a cardiogenic shock group and a congestive heart failure group].

Twelve patients with postinfarction ventricular septal perforation (VSP) were divided into 2 groups based upon the preoperative status and the time interval between the operation and the occurrence of VSP after acute myocardial infarction (AMI). Group I were in cardiogenic shock unresponsive to either pharmacologic supports or IABP, and needed an emergency repair of VSP. The other group (group II) were in congestive heart failure responding to some extent to pharmacologic supports and IABP, and VSP of this group was repaired on the elective or semiemergency basis. Group I comprised of 7 patients, 5 males and 2 females, with a mean age of 65.9 +/- 12.6 years, and group II included 5 patients, 2 males and 3 females with an averaged age of 72.6 +/- 3.4 years. The mean time duration between AMI and the operation, and between the occurrence of VSP and the operation were 3.1 and 1.6 days in group I and 13.4 and 8.0 days in group II. The operative mortalities were 57% in group I and 0% in group II, a remarkable difference. The reasons why group I had a poor prognosis were analysed and were found as follows: (1) group I sustained a larger AMI of anteroseptal area together with the lateral and/or inferior infarctions more often than group II. (2) Group I had frequently multiple organ failure (MOF) even prior to operation due to cardiogenic shock. (3) Group I had severer right ventricular failure than group II, in which the right atrial pressure was markedly elevated. In group I, the right heart failure remained and was prolonged even after surgery reflected by the RAP/LAP ratio over 1 and finally resulting in MOF. To improve surgical results in group I, the operation should be undertaken on the emergency basis before MOF is completed, and patch reconstruction of the left ventricular free wall is recommended in patients with a wide AMI and a high positioned anterior septal perforation. When RV failure is dominant, not only a LV assist device but also a RV assist device may also improve the results.

Aged↗
PubMed1989

Depressed myocardial contractility and normal ejection performance after aortic valve replacement in patients with aortic regurgitation.

Left ventricular cineangiography and pressure measurement were performed in 33 patients with chronic aortic regurgitation before and after aortic valve replacement and in 25 normal control subjects. Stress and volume were analyzed. The 33 patients were divided into three groups based on preoperative end-systolic volume index: 15 with an index of less than 100 ml/m2 (group I), 12 with an index of 100 to 200 ml/m2 (group II), and six with an index of more than 200 ml/m2 (group III). Afterload estimated as end-systolic stress, which was significantly elevated in all groups before operation, returned to normal postoperatively. Systolic pump function improved postoperatively in all groups; group I and group II showing the most improvement with group III still having an abnormal ejection fraction. The ratio of end-systolic stress to end-systolic volume index, which is an index of contractile state that is relatively independent of preload and afterload, was abnormal in each group preoperatively. Postoperatively, the ratio improved in each group (from 2.8 +/- 0.5 to 4.8 +/- 0.9 for group I, from 1.4 +/- 0.3 to 3.2 +/- 0.6 for group II, and from 0.8 +/- 0.2 to 2.6 +/- 0.8 for group III, compared with 5.9 +/- 1.0 for control subjects). Group I had normal values whereas group II and group III had subnormal ratios, suggesting a depressed contractility. All 15 patients in group I had values that fell within the 95% confidence limits of the linear inverse relationship between ejection fraction and end-systolic stress for control subjects. Nine of the 12 patients in group II and all six in group III had values that fell below the 95% confidence limits of the normal ejection fraction-end-systolic stress relationship. Aortic valve replacement may reduce afterload and improve systolic pump function in many patients with aortic regurgitation. However, there is a subgroup of patients who, despite normal or near-normal pump performance as assessed by ejection fraction, have depressed myocardial contractility characterized by an abnormal relationship between end-systolic stress and either ejection fraction or end-systolic volume.

Adolescent↗
PubMed1989

[Clinical experiences with a new membrane oxygenator with low priming volume (D702 MASTER FLO 51), studies during pulsatile and constant flow perfusion].

The newly developed oxygenator "D702" is a compact hollow fiber membrane oxygenator with a priming volume of 170 ml. The maximum flow allowance is 4 liters per/minute. We used this oxygenator in 16 patients (11 infants and children, and 5 adults) undergoing various open heart surgery, and function of this oxygenator was studied. Pulsatile cardiopulmonary bypass was performed in 8 patients and nonpulsatile constant flow perfusion was employed in the remaining 8 patients. Our clinical experience showed excellent maintenance of PaO2 and PaCO2 during both pulsatile and constant flow bypasses. A low pressure drop was encountered across the membrane oxygenator, and therefore, this oxygenator is applicable for pulsatile cardiopulmonary bypass. The D702 is a very useful and applicable for a wide range of patients from infants to adults with a small body structure.

Adolescent↗
PubMed1989

[Successful recovery and long-term survival following postcardiotomy (mitral valve replacement) cardiogenic shock by means of a left ventricular assist device].

A 48-year-old woman who had had mitral regurgitation associated with hypertension and left ventricular hypertrophy underwent mitral valve replacement with a 29 mm xenograft. Following the uneventful procedure, she could not come off cardiopulmonary bypass for 6 times even with an aid of IABP and with re-replacement of the mitral valve using a 29 mm Duromedics prosthesis because of the fear of xenograft malfunction. A left ventricular assist device (LVAD) was then utilized with a resultant dramatic recovery from profound postcardiotomy cardiogenic shock, and cardiopulmonary bypass was successfully terminated. Postoperatively, her hemodynamics were maintained with a LVAD and IABP. Heparin was used to keep the prosthesis from blood clotting by monitoring the ACT. The heart recovered gradually from intraoperative myocardial damage and the LVAD was successfully removed at the 5th postoperative day. Postoperative cardiac catheterization studies showed decreases in left ventricular wall motion and ejection fraction, although improvements of pulmonary hypertension and left ventricular end-diastolic pressure at rest were observed. At present, 1 year and 9 months after the use of LVAD, she is leading nearly normal life of NYHA grade 1. Because of the excellent present clinical condition of this patient, the benefit of a LVAD in perioperative cardiogenic shock is stressed.

Female↗
PubMed1989

[Surgical treatment for chronic constrictive pericarditis through a combined median sternotomy and left anterolateral thoracotomy].

A 61-year-old and a 64-year-old male patients with chronic calcified constrictive pericarditis underwent pericardiectomy through a combined midsternotomy and anterolateral thoracotomy. X-ray films and CT scans of the chests demonstrated prominent calcification of the pericardium. At cardiac catheterization, the right atrial and ventricular enddiastolic pressures were elevated and the typical dip and plateau pressure curves were found in the right ventricle. A combined midsternotomy and left anterolateral thoracotomy gave a good operative view for the surgery. The post-operative course was uneventful in both patients. This combined approach has greater ease of decorticating the lateral to posterior surfaces of the left ventricle than a simple conventional approach.

Chronic Disease↗
PubMed1988

Relations of preoperative hemodynamics and coronary blood flow to improved left ventricular function after valve replacement for aortic regurgitation.

In this study of the limits of reversibility of left ventricular function after aortic valve replacement for aortic regurgitation, measurements were made of pre- and postoperative coronary blood flow and left ventricular volumes. Eighteen patients who had undergone aortic valve replacement for pure aortic regurgitation using the Björk-Shiley valve or the Bicerval valve were restudied an average of 8 +/- 3 months after surgery. Postoperative left ventricular end-systolic and end-diastolic volumes returned to near normal values. The slight left ventricular wall thickening apparent before surgery remained unchanged after surgery and, consequently, left ventricular mass, though somewhat reduced, remained abnormally high. Ejection fraction, which was low preoperatively, returned to normal postoperatively. Total coronary sinus blood flow decreased after surgery, but coronary sinus blood flow per 100 g of left ventricular mass increased. This recovery of coronary flow per unit mass was believed to cause the improvement in left ventricular function. A significant correlation was found between postoperative systolic function and preoperative left ventricular end-systolic and end-diastolic volumes, wall thickness and, especially, left ventricular mass, the latter indicating that, if preoperative left ventricular mass is less than 350 g/m2, postoperative improvement of systolic function is attainable. Another significant correlation was indicated by measurements of coronary sinus blood flow per 100 g of left ventricular mass. If this is greater than 35 ml/min before surgery, a postoperative improvement in systolic function to within the normal range may be expected.

Adult↗
PubMed1988

Excellent patency and growth potential of internal mammary artery grafts in pediatric coronary artery bypass surgery. New evidence for a "live" conduit.

Coronary artery bypass grafting in pediatric patients provides a unique opportunity to evaluate the characteristics of graft material. Twelve pediatric patients with severe coronary artery involvement secondary to Kawasaki disease underwent coronary artery bypass grafting with internal mammary artery and autologous saphenous vein grafts. Eleven patients were boys and one was a girl; their ages ranged from 5 to 13 years (mean age +/- SD, 8.7 +/- 3.0 years). These 12 patients had 17 internal mammary artery and 11 autologous saphenous vein grafts with a mean value of 2.3 +/- 0.7 grafts per patient. Five patients underwent bilateral internal mammary artery grafting with or without concomitant autologous saphenous vein grafting. There was no mortality, and all patients are leading almost normal lives, although strenuous exercise is still prohibited for some. Biplanar cineangiography was performed before and 1 month after (early postoperative period) coronary artery bypass grafting in all patients and was repeated more than 1 year after (late postoperative period) bypass in eight patients. Changes in graft diameter and graft length were assessed by computer-assisted graphic analysis of 10 internal mammary artery grafts and of seven saphenous vein grafts between the early and late postoperative periods. Patency rates of saphenous vein grafts and of internal mammary artery grafts were 91% and 100%, respectively, at the early postoperative period (p = NS), and 50% and 100%, respectively, at the late postoperative period (p less than 0.05). In addition to the excellent patency of internal mammary artery grafts in the late postoperative period, an in situ internal mammary artery graft was found to have grown 125% in length with 112% body growth (112% body surface area) (r = 0.88, p less than 0.001) and to have enlarged 149% in diameter when the native coronary stenosis was tight. In contrast, the lengths of saphenous vein grafts either failed to change or were slightly decreased at the late postoperative period (p = NS). Growth potential of the internal mammary artery graft provides a new demonstration of the viability and adaptability of this graft. We conclude that the internal mammary artery graft is a "live" conduit with potential for growth and adaptation. This growth potential may be the most important reason for its excellent long-term patency, which suggests that in situ internal mammary artery grafts are the graft of choice for pediatric coronary artery bypass grafting.

Adolescent↗
PubMed1987

Results of internal mammary artery-coronary artery bypass surgery and the characteristics of internal mammary artery grafts.

Coronary artery bypass grafting utilizing the internal mammary artery (IMA) was performed in 108 patients with an operative mortality (less than 1 month) of 0% and a hospital mortality of 1.9%. The IMA was used most often in the left anterior descending artery system in combination with saphenous vein grafts (SVG) to the right and left circumflex artery systems. Although the IMA flow was smaller than the SVG flow when measured intraoperatively by an electromagnetic flow meter, postoperative clinical, electrocardiographic, isotopic, angiographic and coronary sinus flow-metric studies all demonstrated that the IMA can respond well to myocardial blood flow demand both at rest and during exercise, resulting in excellent clinical improvements with no detectable signs of flow deficiency. In addition, no signs of ischemia were detected in any of the 15 patients with stenosis in the left main trunk treated with an IMA graft. The IMA graft appears to have a great adaptive capacity to meet increased myocardial demand. Postoperative angiography performed at an average of 3 months after surgery in 60 unselected patients demonstrated an IMA patency rate of 98% in comparison with 88% patency in SVGs to the left anterior descending artery (p less than 0.05). Not only the patency rate, but also the graft wall characteristics were much better in IMA grafts than in SVGs. Some SVGs showed marked wall irregularity as early as 3 months after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Radial dose distribution for 18.3 MeV/n alpha beams in tissue-equivalent gas.

Experimental measurements of the radial restricted linear energy transfer (LETr) for alpha beams of 18.3 MeV/n in tissue-equivalent gas were presented. The radial dose distribution for the alpha beam was deduced from the restricted LET measurements. A differential W value for the alpha particle in the tissue-equivalent gas was also deduced. The result for the differential W value was 29.0 +/- 0.9 eV/ion pair. The radial dose varied according to an inverse-square function with distance from the track center for radii larger than 0.026 micron. The maximum extension of the track, the penumbra radius, as 2.73 +/- 1.67 microns, which was less than predicted by calculations (7-9 microns).

Alpha Particles↗