Biomedical subjects
N Shiiya
Publications and source records attributed to N Shiiya.
[Ruptured aortic aneurysm].
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Alterations in coagulation and fibrinolysis after surgery for aortic aneurysm.
We investigated the alterations in the coagulation and fibrinolysis systems after aortic aneurysm surgery under cardiopulmonary bypass (CPB) while using newly developed "molecular markers". Fibrinogen and antithrombin III (AT-III) decreased after surgery but returned to normal values within three days. The thrombin-antithrombin III complex (TAT) and plasmin-alpha-2-plasmin inhibitor complex (PIC) both showed increased values even preoperatively, which indicated that coagulation and fibrinolysis were activated in some patients with an aortic aneurysm. Both markers maintained a high level for at least 14 days after surgery. The fibrin degradation product (FDP) also showed an increased value before and after surgery. These results apparently showed that coagulation/fibrinolysis had already been activated in some patients and maintained such a state for at least 14 days after surgery. The relation of activated system and postoperative organ dysfunction as well as the means to suppress such activation are also discussed.
Preoperative disseminated intravascular coagulation (DIC) associated with aortic aneurysm--does it need to be corrected before surgery?
Disseminated intravascular coagulation (DIC) is one of the complications accompanying aortic aneurysm. We herein report four patients with aortic aneurysm who had DIC preoperatively. In all four cases, DIC was corrected immediately after surgery; however, in two cases, DIC could not be corrected preoperatively. This prompted us to reconsider the importance of correcting DIC before surgery. Of the four cases reported in this paper, DIC existed even at the time of surgery in two cases, in spite of meticulous treatment with heparin and/or protease inhibitor; however, the DIC could be removed postoperatively even in these two cases. Surgeons should not waste time with intensive DIC treatment preoperatively. If the DIC cannot be corrected within more than 2 weeks of meticulous treatment, surgeons should then perform surgery on the patient. In addition, it is also essential to ensure that the DIC is due to the aneurysm itself and that no other disease processes have been overlooked.
Spinal cord protection during thoracoabdominal aortic aneurysm repair: results of selective reconstruction of the critical segmental arteries guided by evoked spinal cord potential monitoring.
PURPOSE: The purpose of this study is to evaluate the results of spinal cord protection based on selective reconstruction of the segmental arteries. METHODS: Twenty-one patients who underwent repair of aneurysms (nine descending thoracic and 12 thoracoabdominal: three type I, six type II, and three type III) were analyzed. Ten patients had postdissection aneurysms. Operative techniques consisted of evoked spinal cord potential (ESP-dsc) monitoring and femorofemoral bypass in all cases, segmental resection in 12, and mild systemic hypothermia in eight. Arteries critical for cord blood flow were selectively reconstructed; if ESP-dsc showed change after resection of an aortic segment, arteries originating from this segment were reconstructed. RESULTS: ESP-dsc change was observed in 12 patients. Arteries found to be critical were at the T8-L1 level in all but three cases. Selective reconstruction was performed in 10 of these 12 patients. ESP-dsc change could be reversed before reconstruction in four cases, three by control of back-bleeding critical arteries. Selective reconstruction resulted in return of ESP-dsc in seven other patients. Spinal cord injury occurred in five patients, two of whom did not undergo selective reconstruction. CONCLUSION: These results suggest that our current technique allows determination of critical arteries but does not completely prevent injury.
[Clinical results of selective cerebral perfusion during reconstruction of the transverse aortic arch].
Selective cerebral perfusion (SPC) has become a reliable method for brain protection during reconstruction of the transverse aortic arch. However, arterial cannulation technique for the branches of the aortic arch varies among groups, and the necessity of perfusion for the left subclavian artery is controversial. To avoid atheroembolism to the brain and malperfusion of the vertebral arterial system, we carefully selected the arterial cannulation technique according to the result of preoperative ultrasonographic and angiographic evaluation of the branches of the aortic arch, and decided the necessity of perfusion for the left subclavian artery according to the dominance of the two vertebral arteries and the result of pressure monitoring of all three branches. In this report, we analyzed our clinical results of selective cerebral perfusion on 22 consecutive patients, which was performed between April 1992 and December 1993. There were 14 atherosclerotic aneurysms and 8 aortic dissections. The flow rate for SCP was controlled by a single blood pump separate from that for systemic perfusion, with the mean value being 13.1 ml/kg/min. Mean of minimum left superficial temporal arterial pressure was 51 mmHg, mean duration of SCP was 134 minutes, and mean of the lowest esophageal temperature was 17.9 degrees C. Blood pH was regulated with alpha-stat strategy. Arterial cannula for SCP was inserted directly into the vessels through a stab wound in most cases. In three of four patients in whom dissection extended to the branches, a balloon catheter was introduced through the lumen of the aortic arch.(ABSTRACT TRUNCATED AT 250 WORDS)
[A case of dissecting aortic aneurysm and presence of anti-Jr(a) antibody].
A 66-year-old woman was diagnosed as a DeBakey type II dissecting aortic aneurysm with angiography and CT. Antibody screening revealed circulating anti-Jr(a) antibody. Preoperatively, erythropoietin was administered twice a week. Over 24 days, a total of 1200 ml of her blood was removed and stored for autologous transfusion. The dissecting ascending aorta was replaced with the aid of cardiopulmonary bypass. The post operative course was uneventful. By using erythropoietin, pre-donated autologous blood, cell saver, aprotinin and transfusion of fresh autologous blood, it was possible to perform cardiovascular surgery on this patient who had an abnormal antibody. This patient is the first case of repair or dissecting aortic aneurysm with anti-Jr(a) antibody in Japan.
[Acute dissection of the interatrial septum after re-replacement of the mitral valve--a case report].
A 64-year-old man who had received a Carpentier-Edward mitral valve replacement seven years earlier was seen with dyspnea on exertion. After re-replacement of the mitral valve with SJM prosthesis, the patient developed acute left-sided heart failure on the third postoperative day. Transesophageal echocardiography revealed abnormal lumen posterior to the left atrium with regurgitant flow from the left ventricle. Right and left atriotomy revealed dissection of the interatrial septum and after removal of the prosthesis, communication between the left ventricle and the dissected lumen was recognized. After closing the communicating orifice, SJM prosthesis was again sutured on the mitral annulus with sub-annular pledgets to reinforce the annular attachment. Excessive debridement of the annular tissue was thought to be a causative factor to develop the dissection of the interatrial septum after mitral valve replacement.
Clinical application of evoked spinal cord potentials elicited by direct stimulation of the cord during temporary occlusion of the thoracic aorta.
Evoked spinal cord potentials elicited by direct stimulation of the cord were used to monitor spinal cord ischemia in 68 patients undergoing temporary occlusion of the thoracic aorta (29 thoracic nondissecting aortic aneurysms, 9 nondissecting thoracoabdominal aneurysms, and 30 dissecting aneurysms). "Immediate" postoperative paraplegia developed in three patients and "immediate" paraparesis developed in one, whereas "delayed" paraplegia developed in two others. During aortic crossclamping, four response patterns of the spinal cord potentials were obtained: (1) no change (n = 53), (2) change with return (n = 10), (3) change with inconsistent return (n = 2), and (4) change without return (n = 3). Neurologic complications occurred in 2%, 0%, 100% of these groups, respectively. Delayed paraplegia developed on the second postoperative day in only one patient with a false-negative result, and the potentials correlated well with this patient's clinical neurologic recovery. The aortic crossclamp time was significantly longer in the patients with "change with inconsistent return" and "change without return" than in the other two groups (p < 0.01). Femoral artery pressure and the cardiopulmonary bypass flow rate were also significantly lower in these groups than in the other two groups (p < 0.02 and p < 0.01, respectively). We conclude that intraoperative monitoring of direct spinal cord responses is useful for the early detection of spinal cord ischemia for assessing the efficacy of surgical countermeasures.
[Experience of reoperations followed by repairs of abdominal aortic aneurysms].
We experienced 8 cases who required reoperations, including 2 re-redo operations, after repairs of infrarenal abdominal aortic aneurysms. Of 8 patients, one patient developed a new aneurysm due to atherosclerosis in thoraco-abdominal aorta involving all visceral arteries and other 7 patients had aneurysmal formations at proximal anastomotic sites, including 3 suprarenal, 2 juxtarenal and 2 infrarenal aortic lesions. Etiology at initial operation in patients who subsequently developed anastomotic aneurysms included vasculo-Behçet disease in 4, atherosclerosis in 2 and dissecting aortic aneurysms type III due to Marfan syndrome in 1. At reoperation, all who had vasculo-Behçet disease had ruptures of anastomotic sites and 2 patients underwent repairs of dehiscent patch, 1 extra-anatomic bypass between ascending and abdominal aorta and 1 interposition of graft. One patient who had graft infection after repair of abdominal aortic aneurysm required axillo-femoral bypass with removal of infected graft. A patient who had dehiscence of proximal anastomosis after repair of aortoiliac occlusive disease required interposition of graft. Two patients, Marfan syndrome and aneurysm in thoraco-abdominal aorta, underwent graft replacement of thoraco-abdominal aorta concomitant with reconstruction of all visceral arteries. There were 8 patients who required reoperations for aneurysms at distal anastomotic sites after repairs of abdominal aortic aneurysms. Five patients underwent repairs of new aneurysms, including replacement of total arch in 3, descending aorta in 1 and iliac artery in 1. In all cases, no hospital death was noted, however, late deaths were occurred in vasculo-Behçet disease, Marfan syndrome and graft infection. Thus, late result depends on etiology of disease. Although patients who requires reoperation after repair of abdominal aortic aneurysms have higher operative risk factors, early and late results are satisfactory compared to initial operations.
[Surgical aspects of automatic implantable cardioverter defibrillator (AICD) in patients with life-threatening ventricular tachyarrhythmias].
Implantations of automatic implantable cardioverter defibrillator were performed in five patients with life-threatening ventricular tachyarrhythmias. Preoperative diagnoses of arrhythmias were sustained ventricular tachycardia (VT) in two cases, ventricular fibrillation (VF) in two cases and sustained VT+VF in one case. Four of five cases had basic diseases respectively (broad anterior myocardial infarction, dilated cardiomyopathy, arrhythmogenic right ventricular dysplasia, hypertrophic cardiomyopathy), and the other case was idiopathic. Preoperative CTR were 43-65% (mean 57.4%) and left ventricular ejection fraction were 26-76% (mean 51.2%). Implantation of AICD was indicated for patients who survived circulatory arrest or life-threatening VT. Median sternotomy (3) or left antero-lateral thoracotomy (2) were performed for implantation of large-small patch electrodes for defibrillation. AICD generators were implanted in the pocket under abdominal rectal muscle in all cases. Postoperatively myocardial insufficiency, pericarditis, pleuritis occurred in three cases respectively. In the follow-up periods (2-25 months, mean 13 months), AICD worked effectively in two patients with spontaneous VT (6 months, 1 year after operation) and no cardiac death was experienced. We concluded that AICD system is effective for the life-threatening ventricular tachyarrhythmias, although the further estimation in longer follow-up periods are warranted.
Changes in hemodynamics and coronary blood flow during left ventricular assistance with the Hemopump.
The Hemopump, a catheter-mounted left ventricular assist device, has been demonstrated to be effective in supporting patients with potentially reversible cardiac failure. The mechanism of recovery of the hearts with this device is not fully understood. The effects of the Hemopump on hemodynamics and coronary blood flow with and without myocardial ischemia and failure have been studied in 8 anesthetized open-chest dogs. Coronary blood flow in the left circumflex artery was assessed with an intracoronary Doppler catheter. Myocardial ischemia was induced by ligation of the left anterior descending and diagonal branches. The effects of maximum support were compared with those of minimum support. The effects of the Hemopump varied according to cardiac function. When cardiac dysfunction was mild, the Hemopump support slightly reduced myocardial O2 demand (assessed by pressure-work index) by volume unloading. When cardiac dysfunction was severe, total bypass was achieved and myocardial O2 demand decreased by 45%, owing to both volume and pressure unloading. Coronary blood flow was incompletely auto-regulated, and the ratio of blood flow to O2 demand increased.
Endothelin dilates bovine pulmonary circulation and reverses hypoxic pulmonary vasoconstriction.
To assess the effects of endothelin 1 (ET) on the pulmonary and systemic vascular beds simultaneously, we examined the hemodynamic responses to ET in awake calves implanted with a Jarvik total artificial heart (TAH), a device that maintains constant cardiac output (CO). During basal conditions, successive incremental intravenous (i.v.) injections of 1, 3, and 10 micrograms ET caused a dose-dependent decrease in pulmonary arterial pressure (PAP), (from 24 +/- 3 to 15 +/- 1 mm Hg, p less than 0.05) while having no effect on systemic arterial (SAP), left atrial (LAP), and right atrial (RAP) pressures. Administration of 30 micrograms ET i.v. also decreased PAP, had no effect on LAP and RAP, but increased SAP from 100 +/- 6 to 118 +/- 4 mm Hg (p less than 0.05). The decrease in PAP was rapid, occurring within seconds and lasting 10 min, whereas the increase in SAP occurred after 2-5 min and was prolonged for greater than or equal to 20 min. As compared with injection in the right atrium, administration of 30 micrograms ET into the left atrium reduced PAP to a similar extent, but induced a greater increase in SAP (+32.5 +/- 4 vs +17.5 +/- 2 mm Hg, p less than 0.05). ET also dose-dependently reversed the acute pulmonary vasoconstriction induced by inhalation of an hypoxic gas mixture. In all cases, pulmonary vasodilation occurred without evidence of short-term tolerance. The results demonstrate that ET is a potent in vivo pulmonary vasodilator. In calves, the predominant hemodynamic response to ET is pulmonary vasodilation, with systemic vasoconstriction apparent only at higher concentrations of the peptide.
Coronary hemodynamics during hemopump left-intraventricular assistance.
Hemopump left intraventricular pumping (HP) can permit percutaneous transluminal angioplasty (PTCA) in high-risk patients. Benefits may be related to left ventricular unloading or myocardial perfusion improvement, or both. Direct ultrasonic measurements of coronary blood flow were made in the dilated vessel after a successful PTCA in five patients. A 3 Fr intracoronary Doppler catheter was placed in the coronary artery to measure flow velocities (maximal or diastolic velocity; minimum or systolic velocity and mean velocity). A SwanGanz catheter was used to measure the cardiac index and pulmonary capillary wedge pressure. Mean aortic pressures were monitored through an 8 Fr guiding catheter. Measurements were made after a 5-min period of minimal speed (T0) of the HP to avoid retrograde regurgitation through the turbine; during the increase from minimum to maximal speed (T1); after a 5-min period of maximal HP flow (3l/min) (T2) and after HP was pulled back (T3). From T0 to T2, cardiac index rose from 1.93 +/- 0.38 to 3.26 +/- 0.35 l/min/m2 and capillary wedge pressure decreased from 18 +/- 6 to 13 +/- 5 mmHg (p less than 0.05); from T2 to T3, cardiac index decreased to 2.4 +/- 0.4 while capillary wedge pressure increased to 17 +/- 5 (p less than 0.05). Mean arterial pressure and heart rate did not change significantly throughout the study. When the hemopump flow was raised to high speed, coronary blood flow increased immediately but returned shortly to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)
Enhanced O2 transportation during cardiopulmonary bypass in piglets by the use of inositol hexaphosphate loaded red blood cells.
A continuous lysing and resealing of erythrocytes permitted internalization of inositol hexaphosphate (IHP), a strong allosteric effector of Hb, leading to significant rightward shifts of the HbO2 dissociation curve. Twelve piglets were put on cardiopulmonary bypass (CPB) with the heart beating, cooled to 25 degrees C then rewarmed to 37 degrees C before weaning off CPB. AoP, LV pressure, PAP, and cardiac output (CO) were monitored. Blood samples were taken before CPB, at 25 degrees C, at 30 degrees C, at 37 degrees C and after CPB for assessment of blood gases, arterio-venous difference in O2 content, lactates, P50 (partial pressure of O2 at 50% Hb saturation), and ionogram. Control group I included five pigs where the CPB circuit was primed with Ringer's lactate solution and porcine blood. In group II (n = 5), priming was done with Ringer's lactate solution and IHP loaded erythrocytes. P50 was significantly higher during CPB than before surgery in group II (20%), but not in group I (1%). There was a significant increase in VO2 in group II (6.02 ml/min) compared to group I (4.03 ml/min) (p less than 0.05) after CPB. Hemodynamics improved after CPB in group II (mean AoP 42 mmHg and syst LVP 70 mmHg) compared to group I (AoP 25 mmHg and syst LVP 22.5 mmHg). These preliminary results show that O2 transportation at the end of CPB is enhanced and myocardial function is improved in piglets with the use of IHP erythrocytes.
Irreversible drop of systemic vascular resistances in patients implanted with a Jarvik total artificial heart.
Maintenance of the body's perfusion by a total artificial heart (TAH) may result in physiological alterations to the circulatory system. Little has been said about modifications to systemic vascular resistances (SVR) during TAH assistance. This paper reports on two patients implanted with a Jarvik - 70 cc TAH, who died after 1 and 3 days, both with an irreversible drop of SVR related to a complete loss of vascular tone but not related to sepsis. Activation of multiple cascades of inflammation, triggered by the extracorporeal circulation (ECC), is maintained during TAH support. Desperately sick patients might not be able to face the vaso-active situations created by the inflammatory response.
[The intracardial hemopump. A new technique of left ventricle assist device].
A new left ventricular assist device consisting of a canula containing a turbine introduced by retrograde catheterisation was evaluated in the prevention of complications in 9 patients undergoing high risk coronary angioplasty. The good clinical and hemodynamic status during and after coronary dilatation confirmed the system's innocuity and its efficacy each time it could be correctly positioned in the ventricle (6 patients). These extremely encouraging preliminary results suggest that an additional simplification but reducing the size of the canula and increasing turbine flow, allowing percutaneously introduction would constitute a significant development.
[Studies on anastomoses of rat abdominal aorta using the carbon dioxide laser--histological changes and elastic properties of the anastomotic sites].
End-to-end anastomoses of rat abdominal aorta (about 1.8 mm in external diameter) were performed using the carbon dioxide laser, and histological change and dynamic compliance of the anastomotic site were compared with the control group with continuous suture technique. To anastomose vessels with laser energy, four to five stay sutures were placed, and laser energy of 30 to 35 mW with a 100 microns focal spot size was applied to the anastomotic site in the continuous mode. The rats were sacrificed for histological evaluation and measurement of dynamic compliance (Cd) at 2 hours and at 2, 6, and 8 weeks after anastomosis. Cd was calculated from the variables which were measured using the ultrasonic displacement meter at the mean pressure of 55 mmHg with the vessels connecting to the experimental circuit. All laser-assisted and suture anastomoses were patent (laser 21/21, suture 16/16). The rate of aneurysm formation was 4.8% (1/21) for the laser group and 12.5% (2/16) for the suture group. Histological examination showed that the anastomotic site of the laser-assisted anastomosis demonstrated less foreign-body reaction than that of the suture anastomosis and regeneration of the elastic fibers at 6 weeks postoperatively in the optimally coaptated cases. Cd of both laser-assisted and suture anastomoses decreased significantly (p less than 0.01) as compared with that of the untreated aorta. But Cd of the laser-assisted anastomoses had recovered 6 weeks after surgery, and was significantly (p less than 0.05) greater than that of suture anastomoses. From the present study of histological change and dynamic compliance, the results of the laser-assisted arterial anastomoses were more favorable than that of the suture anastomoses.