Hiroyuki Ohnishi

Clinical experience of argatroban for anticoagulation in cardiovascular surgery

PURPOSE We have reviewed our experience with Argatroban-a direct thrombin inhibitor for anticoagulation--in a variety of cardiovascular operations, and in extracorporeal circulation, as a substitute for heparin. SUBJECTS AND METHODS 60 patients receiving anticoagulation with Argatroban were classified into the following four groups. Group 1; 20 patients with anticoagulation therapy after cardiac surgery. Group 2; 8 patients with extracorporeal circulation for continuous hemofiltration for either pre- or post-operative control of acute renal failure. Argatroban was used alone or in combination with nafamostat mesilate. Group 3, one patient with replacement of the descending aorta with left heart assist and 15 patients with percutaneous cardiopulmonary support. And Group 4, 16 patients undergoing vascular surgery including the abdominal aorta. The target activated clotting time was individually set for each group. In Group 1, the coagulofibrinolytic activity and platelet function were measured precisely. Bleeding and complications were examined in all groups. RESULTS Group 1; the targeted activated clotting time of 150-180 seconds was achieved by a dosage of 0.4-0.8 microgram/kg/min Argatroban. Group 2; the activated clotting time of 150-180 seconds was achieved by 0.05-1.6 micrograms/kg/min (concomitance), or by 0.02-2.5 micrograms/kg/min (alone). Group 3; the activated clotting time of 180-200 seconds by 0.05-3.86 micrograms/kg/min. And Group 4; the activated clotting time of around 150 seconds by 2.0 micrograms/kg/min with initial bolus infusion of 0.1 mg/kg. Argatroban did not promote post-surgery bleeding and had no unfavorable effect on coagulo-fibrinolysis or on platelet activity. CONCLUSION Argatroban may be useful as an anticoagulant in the field of cardiovascular surgery as a substitute for heparin, without causing any post-surgery bleeding complication, or influencing the fibrinolytic activities or platelet functions.

Mitral Valve Replacement for a Severely Calcified Mitral Annulus

Abstract  We herein describe a surgical technique in a mitral valve replacement for a hemodialysis patient presenting with mitral valve stenosis and severe mitral annular calcification. Mitral annular calcification extending to the left ventricular myocardium was resected using a cavitron ultrasonic surgical aspirator (CUSA) to make a flat plane from the left atrium to the left ventricle. An autologous pericardium was secured to the posterior left ventricular wall and to the left atrial wall covering the mitral annulus for annular reconstruction. In the posterior mitral annulus, the prosthetic valve was fixed onto this pericardial patch. After the operation, the patient recovered well without any embolic complications. The prosthetic valve functions normally without any perivalvular leakage. Decalcification using the CUSA and the annular reconstruction with a pericardial patch is therefore indicated in valve replacement for patients with severe mitral annular calcification.

Aneurysm of the Right Sinus of Valsalva After Aortic Valve Replacement in Takayasu Arteritis

Abstract  We herein report a case with an aneurysm of the right sinus of Valsalva, which developed 14 years after an aortic valve replacement (AVR) for aortic regurgitation caused by Takayasu arteritis. The aortic wall around the right coronary artery ostium showed calcification, as a result, the modified Bentall procedure and coronary artery bypass to the right coronary artery were successfully performed. A pathological study of the resected aortic sinus wall showed a disruption of the elastic fibers in the media, granuloma formation, and a marked proliferation of the collagen fibers in the adventitia, and these findings were compatible with Takayasu arteritis. The development of an aneurysm of the sinus of Valsalva late after AVR indicates the necessity of a close and lifelong follow‐up for patients with Takayasu arteritis, especially focusing on the aortic root morphology.

Surgical Technique for Massive Mural Thrombus in the Left Atrium

Abstract  A surgical case of a massive mural thrombus in the left atrium associated with valvular heart disease is herein presented. The fresh autologous pericardium was used to cover the roughened left atrial endocardium after the removal of the mural thrombus. This procedure seems useful to prevent not only the perioperative thromboembolism caused by the dislodgement of the fragmented small thrombus but also any long‐term future thrombus formation by creating a smooth surface layer with the autologous pericardium.

A safer technique of aortic root replacement after aortic valve replacement

Aortic root replacement after aortic valve replacement (AVR) is often complicated by bleeding around the aortic root, which increases the risk of morbidity and mortality, making it a technically challenging procedure. We describe a new technique of aortic root replacement designed to minimize bleeding around the aortic root. This surgical technique focuses on safe dissection and exposure of the aortic root to avoid inadvertent entry into the right atrium or right ventricle; on modifying the proximal anastomosis of the graft to the aortic annulus; and on performing a coronary artery reimplantation that achieves complete hemostasis at the suture lines. We performed aortic root replacement after AVR in four patients over a 4-year period, without encountering any bleeding around the aortic root.

Aortic dissection late after aortic valve replacement

We experienced 3 cases of an aortic dissection occurring late after an aortic valve replacement, and successfully treated by an aortic root replacement. An aortic dissection involving the ascending aorta can develop late after an aortic valve replacement, and such an occurrence is associated with a high mortality and morbidity. The development of effective surgical strategies at the initial aortic valve surgery, strict control of blood pressure after aortic valve replacement, serial evaluations of aortic size, and the prophylactic replacement of the ascending aorta for patients with aortic dilatation after aortic valve replacement, all play clinically important roles in preventing an aortic dissection after aortic valve replacement. When an aortic dissection occurs in patients with a previous aortic valve replacement, an aortic root replacement should be performed in order to avoid leaving the fragile diseased aortic wall including the sinus of Valsalva.

Mitral valve repair for broad, asymmetrical prolapse in the posterior mitral leaflet

We designed a mitral valve repair and successfully performed this repair for a case of broad, asymmetrical prolapse in the middle scallop of the posterior mitral leaflet. The repair procedure consists of making a fan-shaped leaflet by resecting the prolapsed portion in a trapezoid shape with detachment of the leaflet along the annulus and leaflet reapproximation by rotating this fan-shaped leaflet. This technique can utilize more leaflet tissue for filling the gap made by leaflet resection than the quadrangular resection and suture technique. As a result, it helps reduce tension on the suture lines, avoids the need for extensive annular plication, and also avoids leaflet distortion while making it easier to adjust the height of the leaflets that should be reapproximated. The essence of this mitral valve repair exists in the “resecting line of the leaflet,” which has not yet been reported.

Emergent Pulmonary Embolectomy: The Efficacy of Percutaneous Cardiopulmonary Support as a Bridge to Surgery

Five patients with acute pulmonary embolism (APE) underwent operation by the author between 1985 and 1990 because of circulatory collapse. All were weaned from extracorporeal circulation, but two patients were lost because of bleeding tendency and neurological deficit. Considering such experiences until 1990, we have changed our strategy in the surgical management of APE at our institution. Since 1991, 33 patients with massive APE have been treated, most with thrombolytic therapy. Transthoratic echocardiogram is very effective in detecting APE as an initial diagnostic procedure and confirmed marked dilation of the right ventricle with a small left ventricle. Four patients were seen with severe cardiopulmonary collapse, and all received cardiopulmonary resuscitation. Acute pulmonary embolism was strongly suspected, and percutaneous cardiopulmonary support (PCPS) was initiated for resuscitation and the maintenance of circulation for three patients. After resuscitation, trans-esophageal echocardiography was done and showed thrombus in the main pulmonary artery. Three patients were taken to the operating room without the conventional definitive diagnostic studies. One patient responded to resuscitation without PCPS, underwent pulmonary angiography, and received thrombolytic therapy followed by emergent pulmonary embolectomy. All four patients were subsequently discharged from the hospital and are doing well now. The clinical course of the four patients is described, and management of massive pulmonary embolism and the efficacy of PCPS as a bridge to operation are discussed. It is concluded that surgical treatment for moribund APE is effective and can be performed safely, and PCPS is also effective as a bridge to operation or alternative diagnostic procedure or treatment.

A case of the ascending aorta and aortic arch replacement with thrombo-occlusion of distal arch and descending aorta suround the modified elephant trunk graft

We report a 65-year-old female who had a extensive thoracic aneurysm from ascending aorta to descending thoracic aorta. The patient underwent a graft replacement of ascending aorta and aortic arch using modified elephant trunk method. The surgery was carried out through median sternotomy with profound hypothermia and selective cerebral perfusion. Postoperatively, the patient was recovered without any complications except bronchial asthma. Postoperative chest computed tomography showed that the surrounding space of the elephant trunk vascular graft inserted into distal arch and descending aneurysm was mostly occupied with thrombus. Therefore, we considered that the second operation on the descending aorta is not necessary at this point and careful attention to the size and shape of the descending aneurysm should be paid.