Tomoyuki Wada

Limb ischemia and reperfusion during abdominal aortic aneurysm surgery

PurposeAbdominal aortic aneurysm (AAA) surgery involves ischemia and reperfusion of the lower extremities, but assessing the pathophysiological changes is difficult. We evaluated the extent and time course of ischemia–reperfusion injury of the lower extremities during AAA surgery.MethodsTo monitor oxygen metabolism, two near-infrared spectroscopy (NIRS) probes were positioned on each calf muscle of nine patients undergoing AAA surgery. Lactate and pH were also measured in both iliac veins.ResultsNear-infrared spectroscopy signals responded sensitively to aortic cross-clamping and declamping. Lactate increased gradually and exponentially during aortic cross-clamping, and reconstruction of the first iliac artery resulted in a further but transient increase in ipsilateral venous lactate. The time course of the pH level after declamping was almost a mirror image of that of lactate. Reconstruction of the first iliac artery did not affect the contralateral NIRS signals, lactate, or pH.ConclusionsNear-infrared spectroscopy may be useful for monitoring limb ischemia during AAA surgery. The transient increase in lactate and the transient decrease in pH after first declamping may contribute to the mechanism of declamping shock. The fact that first declamping did not affect measurements on the other side shows that contralateral ischemia progresses steadily after reconstruction of the first iliac artery. Therefore, reconstruction of the second iliac artery should be done as soon as possible.

Endovascular aortic arch reconstruction using in situ stent-graft fenestration in the brachiocephalic artery.

A patient who had previously undergone retrosternal gastric tube reconstruction for esophageal cancer presented with an aortic arch aneurysm. The patient was treated with endovascular stent-graft placement without median sternotomy, followed by revascularization of the brachiocephalic trunk using percutaneous in situ graft fenestration. A 9-month follow-up examination revealed marked regression of the aneurysm with patency of the stent-graft, without any complications. This in situ fenestration technique may extend the limits of thoracic endovascular therapy for patients who are unsuitable for sternotomy or aortic side-clamping.

“Squid-Capture” Modified In Situ Stent–Graft Fenestration Technique for Aortic Arch Aneurysm Repair

An 83-year-old female was found to have an fusiform aneurysm in the aortic arch. She was deemed to be a high surgical risk; therefore, endovascular stent–graft placement followed by revascularization of the brachiocephalic trunk using in situ stent–graft fenestration was considered. However, the safe application of fenestration was deemed difficult due to the tortuosity of the brachiocephalic artery. The patient was successfully treated with the aid of the “squid-capture” technique, which consists of deployment of the stent–graft in a snare wire loop that was advanced from the brachiocephalic artery and fenestration of the stent–graft with the support of the loop. A follow-up exam revealed complete sealing of the aneurysm without any complications. The squid-capture technique allows for the safe and secure puncture of the graft.

Synaptic degradation of cardiac autonomic nerves in streptozotocin-induced diabetic rats

BACKGROUND Cardiac autonomic neuropathy (CAN) is a common complication in type I diabetes mellitus (DM). Nevertheless, the relationship between functional and structural disturbances of cardiac autonomic nerves remains unclear. METHODS AND RESULTS To clarify this relationship, we studied heart rate variability (HRV) and ultrastructural changes of cardiac autonomic nerves in streptozotocin (STZ)-induced DM in rats. STZ was injected (65mg/kg intravenous) into the tail vein of male Wistar rats to destroy β cells in the pancreatic islets. After STZ injection, fasting blood sugar (FBS) increased from baseline values of 75±3mg/dl up to 328±12mg/dl within 1week and it reached up to 353±24mg/dl within 17weeks. HR in these rats was decreased within 20days and low HR was maintained for the observation period. TP and HF power started decreasing 20days after STZ injection, and this decrease progressed throughout the observation period. The L/H power ratio was decreased 80days after STZ. Electron microscopic findings indicated a depletion of neurotransmitter vesicles and degradation of parasympathetic nerve endings but not of sympathetic ones in the SA node region of the heart in the early stages of DM. In the late stages of DM, the same region showed degradation of both sympathetic and parasympathetic nerve endings. CONCLUSION Synaptic degradation in parasympathetic nerves immediately after the onset of DM, and in sympathetic nerves much later in the development of DM is consistent with functional derangements in cardiac autonomic nerve activities assessed by HRV analysis.

Effect of Prostaglandin E1 on Ischemia–Reperfusion Injury During Abdominal Aortic Aneurysm Surgery

ObjectiveAbdominal aortic aneurysm (AAA) surgery subjects the lower extremities to ischemia and reperfusion. Although it is not extensive or prolonged, ischemia of the lower extremities during aortic cross-clamping is gradually and steadily induced. We studied the effects of prostaglandin E1 (PGE1) on ischemia–reperfusion injury of the lower extremities during AAA repair.MethodsDuring AAA surgery, two near-infrared spectroscopy probes were positioned on each calf muscle to monitor oxygen metabolism in the lower extremities. We also measured lactate concentration in both iliac veins.ResultsNear-infrared spectroscopy signals responded sensitively to aortic cross-clamping and declamping. Lactate increased time-dependently during aortic cross-clamping. The continuous venous administration of PGE1 (20 ng/kg per minute) inhibited the accumulation of lactate during aortic cross-clamping. Declamping of the first iliac artery resulted in a further but transient increase in ipsilateral venous lactate, which may be one component in the mechanism of declamping shock. Prostaglandin E1 eliminated the transient increase in ipsilateral lactate. The administration of PGE1 inhibited the contralateral accumulation of lactate after first declamping, and the lactate level decreased gradually before the second declamping.ConclusionsProstaglandin E1 seems to have a protective effect against ischemia–reperfusion injury of the lower extremities during AAA surgery.

A new method for protection from shower embolism during TEVAR on a shaggy aorta

The case of a patient with a thoracoabdominal aortic aneurysm accompanied by a shaggy aorta, in whom embolism was prevented by a graft used in debranching and placement of an extracorporeal shunt during thoracic endovascular aortic repair, called the “block and trap method”, is presented. Two-staged operations were performed using Y graft replacement, debranching bypass, and thoracic endovascular aortic repair during which a temporary shunt line with a blood filter was made involving the femoral artery and vein. The method of trapping emboli in a filter in an external shunt appears effective.

Cardiac autonomic nerve abnormalities in chronic heart failure are associated with presynaptic vagal nerve degeneration

BACKGROUND Understanding of the functional and structural disturbances of cardiac autonomic nerves in ventricular hypertrophy and eventual chronic heart failure (CHF) remains unclear. METHODS AND RESULTS ECG signals were obtained by a radio transmitter from male Wistar rats that received monocrotaline (MCT) via subcutaneous injection. Heart rate (HR) and HR variability (HRV) were analyzed. The RR interval, total power (TP), low frequency (LF) power, high frequency (HF) power, and LF/HF (L/H) power ratio were measured. Ultrastructural changes in cardiac autonomic nerves at the sinoatrial (SA) node region were studied using an electron microscope. TP and HF powers in MCT-induced right ventricular hypertrophy (RVH) and eventual CHF were significantly decreased, and HR was significantly increased at week 5 or later after the MCT injection. The electron microscopic findings indicated the depletion of neurotransmitter vesicles and degradation of parasympathetic but not sympathetic nerve endings in the SA node region of the heart. CONCLUSION MCT-induced RVH and CHF rats showed presynaptic vagal nerve degradation prior to sympathetic nerve derangement in the heart.

An implantation of DDD epicardial pacemaker through ministernotomy in a patient with a superior vena cava occlusion.

SAKO, H., et al.: An Implantation of DDD Epicardial Pacemaker Through Ministernotomy in a Patient with a Superior Vena Cava Occlusion. We successfully implanted a DDD epicardial pacemaker through a limited lower sternotomy in a patient whose superior vena cava had been occluded. Both epicardial leads were connected to the generator placed in the existing subcutaneous pocket on the left pectoral region through the second intercostal space. This approach provided excellent exposure and easy access to both the right appendage and the right ventricle. The combined procedure of epicardial DDD pacemaker implantation through a limited lower sternotomy with placement of the generator in the pectoral subcutaneous pocket is one of the better methods when intravenous lead implantation is difficult. (PACE 2003; 26:778–780)

Pinhole rupture of aortic root aneurysm with severe atherosclerotic change

We report two cases of the rupture of calcified aortic root aneurysms that were successfully treated by emergency operations. One patient underwent Bentalls operation, and for the other, we performed a valve-sparing operation. Because their aneurysms revealed pear-like configurations with aortic regurgitation, the findings were consistent with annuloaortic ectasia (AAE). However, both cases were unlike typical AAE in that the aortic walls showed severe atherosclerotic change, with little sign of cystic medial necrosis. It was very interesting that each rupture point was a very small pinhole originating from one of the atherosclerotic ulcers.

Denervation and reinnervation of the heart after aortic surgery, estimated by 123I-metaiodobenzylguanidine scintigraphy.

PurposeTo investigate whether sympathetic nerve injury occurs during aortic surgery and how reinnervation takes place afterward.MethodsImaging with 123I-metaiodobenzylguanidine (MIBG) was performed in 12 patients (aortic group) who underwent aortic surgery (ascending replacement 3, ascending-arch replacement 9) before and 3 weeks after surgery. In 8 of 12 patients, MIBG scintigraphy was performed 1 and 2 years after surgery. Twelve patients (control group) who underwent open-heart surgery (mitral valve repair: 11; tricuspid valve replacement: 1) were studied using MIBG scintigraphy. The heart-to-mediastinum (H/M) activity ratio was obtained from planar images. The myocardial single-photon-emission computed tomography image was divided into five segments and the regional tracer uptake was scored from 0 = absent to 3 = normal uptake.ResultsNo significant difference in the H/M ratio in either early and delayed planar scans was observed between both groups before surgery. The H/M ratios significantly decreased 3 weeks after surgery in the aortic group, whereas there was no significant change in the control group. The H/M ratio did not recover to the preoperative level within 2 years. In these 8 patients, the regional uptake of MIBG improved in the anterior and septal regions 1 year after surgery.ConclusionDuring ascending or ascending-arch replacement, the sympathetic nerve was globally denervated and slight reinnervation was observed within 2 years. The anterior and septal regions showed a rapid reinnervation, whereas other regions did not.