ABSTRACT
STUDY DESIGN: Animal study. PURPOSE: To review the present warning point criteria of the compound muscle action potential (CMAP) and investigate new criteria for spinal surgery safety using an animal model. OVERVIEW OF LITERATURE: Little is known about correlation palesis and amplitude of spinal cord monitoring. METHODS: After laminectomy of the tenth thoracic spinal lamina, 2-140 g force was delivered to the spinal cord with a tension gage to create a bilateral contusion injury. The study morphology change of the CMAP wave and locomotor scale were evaluated for one month. RESULTS: Four different types of wave morphology changes were observed: no change, amplitude decrease only, morphology change only, and amplitude and morphology change. Amplitude and morphology changed simultaneously and significantly as the injury force increased (p<0.05) Locomotor scale in the amplitude and morphology group worsened more than the other groups. CONCLUSIONS: Amplitude and morphology change of the CMAP wave exists and could be the key of the alarm point in CMAP.
Subject(s)
Animals , Action Potentials , Contusions , Gravitation , Laminectomy , Models, Animal , Spinal CordABSTRACT
This study evaluated factors influencing residual aortic regurgitation (AR) after valve re-suspension surgery for acute type A aortic dissection. From January 1996 through December 2002, 63 patients were treated for acute type A dissection at our institution. Among these 63 patients, pre-and postoperative echocardiograms were available in 38 patients who underwent surgery combined with native aortic valve re-suspension. These 38 patients were divided into 2 groups according to the postoperative AR grade, i. e.: AR group: AR grade≥II (<i>n</i>=6), no-AR group: AR grade≤I (<i>n</i>=32). The severity of pre and postoperative AR was assessed by transthoracic or transesophageal echocardiography. The preoperative diameters of mid ascending aorta and sinotubular junction, and the percentage of the circumference of the dissection at the sinotubular junction level was measured by enhanced CT scan. Preoperative patient backgrounds were similar in both groups. The preoperative AR grade in the AR group was significantly greater than that of the no-AR group (2.25±1.17: 0.69±0.91, <i>p</i><0.001). The tear was more frequently located in the ascending aorta in the AR group than in the no-AR group (66.7%: 37.5%, <i>p</i><0.05). The percentage of circumference of the dissection at the sinotubular junction level did not affect the preoperative AR grade, but it did show a tendency to influence the severity of postoperative AR, though the difference was not significant. Three patients (7.9%) had AR grade III at the time of discharge, but did not clinically require further surgical intervention. Preoperative significant AR and the location of the tear in the ascending aorta are associated with postoperative residual AR after aortic valve re-suspension. The percentage of circumference of the dissection at the sinotubular junction level might influence the severity of postoperative AR.
ABSTRACT
The patient was a 70-year-old woman with severe aortic stenosis and familial hyperlipidemia which was diagnosed in 1994. The patient was admitted as an emergency case due to syncope in 2002. According to ultrasound cardiography (UCG), the pressure gradient of the aortic valve was 120.7mmHg, and the diameter of the aortic valve annulus was 16.7mm. Computed tomography showed porcelain aorta from the annulus of aortic valve to the ascending aorta. On cardiac catheterization, the pressure gradient was 96mmHg, AVA was 0.4cm<sup>2</sup>, and the ejection fraction was 38.7%. Since these findings suggested that conventional AVR was difficult, thoracotomy was performed at the left 5th intercostal level, and apicoaortic valved conduit (valved graft: SJM19HP, Intergard 22mm+Medtronic apical LV connector) was implanted. Postoperative cine MRI showed that most of the cardiac output (87%, 3.29<i>l</i>/min) flowed through the conduit, with the flow via the aortic valve accounting for 13%, 0.51<i>l</i>/min. This surgical procedure can be an effective alternative when conventional AVR is difficult.