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Biomedical subjects

S Nawa

Publications and source records attributed to S Nawa.

At least 55 records · Page 3Linked to original sources
PubMed1988

New extension of the Fontan principle: inferior vena cava-pulmonary artery bridge operation.

A new modification of the Fontan operation for complex cardiac anomalies is described. The technique comprises superior vena cava-pulmonary artery anastomosis and inferior vena cava-pulmonary artery bridging via a composite conduit connected to the inferior vena cava via the right atrium, totally excluding the right heart. The procedure was applied to a patient with complex cardiac abnormalities associated with asplenia. After operation the patient had good haemodynamic function initially though he died from multiorgan failure after airway bleeding on the 24th postoperative day. The procedure is a simple alternative to the complicated atrial partition required for the conventional Fontan operation.

Anastomosis, Surgical↗
PubMed1988

Efficacy of intra-aortic balloon pumping for failing Fontan circulation.

The Fontan circulation occasionally cannot be sustained by currently available medical treatment. In these circumstances, mechanical assistance to the Fontan circulation should be considered. We have experienced three cases where Fontan circulation was assisted by intra-aortic balloon pumping (IABP). The hemodynamic improvement and weaning from IABP were successfully achieved in all cases. One patient survived the serious postoperative course with the aid of IAPB, and two patients died following multiorgan failure, though the circulation had eventually been re-established. By studying the postoperative hemodynamics assisted by IABP, it is concluded that IABP is a reasonable, efficacious strategy to support and to re-establish the failing Fontan circulation, though the changes in hemodynamic variables will not immediately coincide with IABP application.

Adolescent↗
PubMed1988

Oxygenated perfluorocarbon, recombinant human superoxide dismutase, and catalase ameliorate free radical induced myocardial injury during heart preservation and transplantation.

The effect of free radical scavengers on free radical-induced myocardial injury during heart preservation and transplantation was examined. Four groups of nine hearts each were harvested from mongrel dogs (12.5 to 16.5 kg) and orthotopically transplanted to size-matched recipients. All hearts received a continuous perfusion of oxygenated modified Collins' solution (group A). In addition, groups B, C, and D received Fluosol DA and albumin. Preservation perfusion was performed for 18 hours, at 4 degrees C, pH = 7.4, and 20 mm Hg. In group C, recombinant human superoxide dismutase (4,080 U/mg, 20 mg/kg) and bovine catalase (46,200 U/mg, 20 mg/kg) were administered only during preservation perfusion. In group D, these scavengers were administered just before and during reperfusion for 1 hour. Hemodynamic studies were performed before excision of the donor hearts and 1 hour after the termination of cardiopulmonary bypass. Creatinine kinase MB isoenzyme and thiobarbituric acid reactive substance levels in the coronary effluent were determined during preservation perfusion and reperfusion. Only group A showed a significant heart weight gain (p less than 0.05) and a decline in passive compliance (p less than 0.05) during preservation. Lactate release was higher in group A than in the groups receiving Fluosol DA. In contrast, pyruvate levels in group A were lower than in other groups. The generation of free radicals stayed at a low level during preservation, but significantly increased during reperfusion and was associated with a corresponding increase in creatinine kinase MB isoenzyme. Perfusion with a perfluorochemical solution (group B) inhibited the sharp rise in levels of thiobarbituric acid reactive substances and of creatinine kinase MB isoenzyme and improved cardiac function during reperfusion (versus group A). Exogeneous free radical scavengers administered just before and during reperfusion (group D) significantly ameliorated thiobarbituric acid reactive substances and creatinine kinase MB isoenzyme levels and also induced a significant hemodynamic improvement during reperfusion. However, administration of scavengers during preservation did not. This study demonstrates that the generation of free radicals is primarily significant during reperfusion and reoxygenation after ischemia. Thus the best time for administration of scavengers is just before and just after the onset of reperfusion. Furthermore, perfusion with perfluorochemicals effectively maintains aerobic metabolism and ameliorates free radical damage during this period.

Animals↗
PubMed1987

Intermittently stuck occluder: case report of an unusual complication with the use of an aortic Omniscience prosthesis.

An occluder which intermittently became stuck in the open position with concomitant aortic regurgitation was encountered in a patient subjected to an aortic valve replacement with a 23 Omniscience prosthetic valve. The patient was intermittently aware of the complete momentary disappearances of the valve sounds, the etiology of which could not be discerned. During fluoroscopic examination, the occluder became stuck for a few cardiac cycles in what appeared to be the fully open position before finally moving. Prosthetic valve malfunction was thus diagnosed. The emergency operation was successful. Operative findings revealed that a thin thrombus had developed in a curtain-like fashion on the left ventricular face of the prosthesis with mild tissue overgrowth along the perimeter of the valve. The Omniscience prosthesis was replaced with a 19-mm St. Jude Medical prosthesis, and the patient's postoperative course has been uneventful.

Adult↗
PubMed1987

Characteristics of chronically paced cardiac functions in the congenital complete atrioventricular block.

Characteristics of morphology, cardiac function, and cardiac reserve at late state were evaluated at rest, by changing the pacing rates, and after exercise in patients with ventricular pacemakers for isolated congenital complete atrioventricular block. Heart size was reduced statistically after pacemaker implantation, and concentric myocardial hypertrophy was observed. Cardiac pump functions at rest seemed fairly well compensated by increased ejection fraction, but the cardiac index was still lower than that of the normal heart. Responses of cardiac function towards the changing rates were considered satisfactory, and those variables had statistic correlations with the pacing rates. After exercise, significant increase of cardiac pump function and also statistic acceleration of myocardial function were observed. This fact proved that cardiac reserve was good, although the increased cardiac output after exercise was still insufficient without an increase in heart rate. More physiological pacing modes would be required as currently recommended.

Adolescent↗
PubMed1987

Traumatic combined valve lesions with aneurysm of the sinus of Valsalva causing late onset of heart failure.

A 23 year old man was operated on because severe incompetence of the aortic, mitral, and tricuspid valve caused congestive heart failure five months after a violent steering wheel injury. The following abnormalities were found at operation: a disrupted right coronary cusp, a torn chorda of the anterior mitral leaflet, a dilated tricuspid annulus, and an intimal tear on the aortic root near the right coronary ostium that had developed into an aneurysm of the sinus of Valsalva.

Accidents, Traffic↗
PubMed1987

Pulmonary artery connection in the Fontan procedure. Flexible polytetrafluoroethylene conduit for expansion.

From clinical experiences with the Fontan operation in six cases, a few practical contrivances and operative steps are described. We stress that meticulous care should be taken not to cause any stenotic complication in the outflow tract toward the pulmonary artery, particularly by traction of the right atrial appendage only to achieve a direct anastomosis. Conduit repair would be necessitated by cases in order to expand the indicative criteria vertically as well as horizontally. For conduit material, we used consecutively nonvalved polytetrafluoroethylene that was reinforced by handmade stainless steel wire ring (Gore-Tex, Inc) or by spirally built-in stent (IMPRA, Inc). The latter was eventually useful in obtaining natural curving of the conduit without kinking or compression. Some contrivances in anastomosing a conduit were also proposed to achieve an excellent result. We believe these practical contrivances will serve for expansion of the indicative criteria and promise improved operative outcome.

Adolescent↗
PubMed1987

Serial evaluation of cardiac function with aortic regurgitation caused by serious aortic lesions. A preliminary comparative study with isolated chronic aortic incompetence.

Clinical and hemodynamic appearances of aortic regurgitation caused by serious aortic lesions (AR-Ao-group) seemed more deteriorated than those with isolated chronic aortic regurgitation (AR-group). Often postoperative course and operative outcome are smooth and satisfactory in the AR-Ao-group. To support this observation, serial changes of left ventricular (LV) function and LV sphericity were evaluated before and after operation in ten cases in the AR-Ao-group and compared with those in the AR-group. Before operation, there were no significant differences in LV function between the two groups. Postoperative improvement of LV sphericity and LV function were statistically better in the AR-Ao-group. The LV function reserve was considered sufficiently retained in the AR-Ao-group. Results with this study supported that clinical observation. Therefore, the total correction, at the same time of aortic incompetence and aortic lesions is recommended.

Adult↗
PubMed1987

Echocardiographic prediction of postoperative low cardiac output syndrome in patients with mitral stenosis.

Thirty-eight patients were operated on for mitral stenosis between March 1979 and September 1981. Thirty-six of them were examined as to their age, symptom duration, chest roentgenograms, electrocardiograms and echocardiograms to obtain various indices of left ventricular function. The usefulness of these indices as preoperative risk factors for predicting postoperative low cardiac output syndrome (LOS) was investigated. Cases which had values of ejection fraction, cardiac index, percent fiber shortening or mean velocity of circumferential fiber shortening less than 0.45, 2.0 l/min/m2, 25% and 0.80 circ/sec, respectively, in the preoperative echocardiographic examination were associated with a greater chance of postoperative LOS. Each of these factors was independently useful as a risk factor in cardiac surgery for mitral stenosis. Moreover, it was revealed that the combination of a preoperative percent fractional shortening (%FS) of less than 30% and a cardiac index smaller than 2.0 l/min/m2 indicated a strong predisposition toward postoperative LOS.

Adult↗
PubMed1986

An unusual complication of a myocardial electrode--apatite mantle on the platinum-iridium spurs.

A case of a high excitation threshold that occurred 2 years 5 months after the initial implantation of pacemaker electrodes is described in a girl 4 years 3 months of age. This complication was considered to be due to calcification of the platinum-iridium electrode spurs. The calcified material was shown to be a kind of apatite using the X-ray powder diffraction method. This complication is rare, but it must be kept in mind since battery longevity has markedly improved in recent years.

Apatites↗