Shonosuke Matsushita

The minimum coronary artery diameter in which coronary spasm can be identified by synchrotron radiation coronary angiography

BACKGROUND Coronary vasospasm is defined as a temporary, intense narrowing of the coronary conduit artery. It brings about ischemic chest pain and becomes one of the causes of myocardial infarction. Coronary spasms are divided into two categories. One is the coronary spasm of the conduit artery and the other is the coronary microvascular spasm. Although coronary spasms are diagnosed with the images of coronary angiography, microvascular spasms cannot be diagnosed because of the limitations of conventional angiographic systems. However, synchrotron radiation coronary angiography (SRCA) can identify coronary arteries down to 100 microm in diameter in the beating heart and 50 microm in arrested heart. AIM The purpose of this study was to confirm whether microvascular spasms could be identified or not using SRCA, and then down that size identification was possible. METHODS The Langendorff perfusion system with isolated rat hearts was employed. Krebs-Henseleit solution (KH solution) was used as a perfusate. 10mM of 4-aminopyridine (4-AP: a voltage-gated potassium channel blocker; spasm inducer) was added to the KH solution and maintained for 5 min. SRCA was performed at pre-, during and 10 min after cessation of the KH solution with 4-AP. Coronary spasms were defined as a temporal 75% reduction of coronary arterial diameter. RESULTS AND CONCLUSION Multiple sizes of coronary arteries showed coronary spasms. The minimum stenosed coronary artery size was 100 microm. Since coronary microvascular spasms are seen in the arterioles (50-400 microm), coronary microvascular spasms may be diagnosed with the use of synchrotron radiation coronary angiography.

The Role of CCL5 in the Ability of Adipose Tissue-Derived Mesenchymal Stem Cells to Support Repair of Ischemic Regions

Mesenchymal stem cells (MSC) are multipotent and possess high proliferative activity, and thus are thought to be a reliable cell source for cell therapies. Here, we isolated MSC from adult tissues--bone marrow (BM-MSC), dental tissue (DT-MSC), and adipose tissue (AT-MSC)--to compare how autotransplantation of these MSC effectively supports the repair of bone fracture and ischemic tissue. An analysis by in vitro differentiation assays showed no significant difference among these MSC. The degree of calcification at the joint region of bone fracture was higher in mice transplanted with AT-MSC than in mice transplanted with BM-MSC or DT-MSC. To compare the abilities of MSC, characterize how those MSC affect the repair of ischemic tissue, vascular occlusion was performed by ligation of the femoral artery and vein. Of note, the blood flow in the ischemic region rapidly increased in mice injected with AT-MSC, as contrasted with mice injected with BM- or DT-MSC. The number of CD45- and F4/80-positive cells at the femoral region was higher in AT-MSC recipients than in recipients of BM-MSC or DT-MSC. We evaluated the mRNA expression of angiogenic and migration factors in MSC and found the expression of CCL5 mRNA was higher in AT-MSC than in BM-MSC or DT-MSC. Transplantation of AT-MSC with impaired expression of CCL5 clearly showed a significant delay in the recovery of blood flow compared with the control. These findings have fundamental implications for the modulation of AT-MSC in the repair of vasculature and bone fracture.

Surgical removal of infected pacemaker leads without cardiopulmonary bypass after failed extraction using the Excimer Laser Sheath Extraction System

With the growing number of cardiac pacemakers and internal cardioverter defibrillator implantations, problems with endocardial lead infection have been increasing. The newly developed Excimer Laser Sheath Lead Extraction System has been recognized as being highly useful for removing chronic infected leads. However, serious bleeding complications are a concern when this system is used. Here we report our experience with a 67-year-old man who was diagnosed with pacemaker endocarditis. Initially, lead removal was attempted using the Excimer Laser Sheath Extraction System, though this was abandoned because of severe adhesion of the leads and the junction of the supra vena cava (SVC) with the right atrium. Surgical removal of the leads was performed without using cardiopulmonary bypass and the leads were removed without any complications. During surgery, we found there was a silent perforation of the innominate vein brought about by the Excimer Laser Sheath System. Also, the junction of the SVC with the right atrium was thought to be an area potentially at high risk of perforation, because of a lack of surrounding tissue. It is our opinion that those who carry out procedures with the Excimer Laser Sheath System should understand the potential risk of perforation based on cardiac anatomy and should be prepared for lethal bleeding complications. Also, for emergent situations, we believe that close backup by a cardiovascular surgical team should be considered essential for performing the Excimer Laser Sheath Lead Extraction safely.

Reducing the dose of contrast medium in angiography by use of a highly sensitive receiver and synchrotron radiation system.

OBJECTIVE Contrast medium causes side effects such as contrast-induced nephropathy, and the dose of contrast medium is a risk factor in their occurrence. To reduce doses of contrast medium, we developed an angiographic system with high definition and high sensitivity and reviewed its effectiveness. The system entails synchrotron radiation, which is characterized by high photon density and straightness of beam that together result in high resolution, and a high-gain avalanche rushing amorphous photoconductor receiver, which is 100 times more sensitive than conventional charge-coupled device cameras. MATERIALS AND METHODS Diluted contrast medium was administered, and angiography of rat hindlimbs was performed with synchrotron radiation and the high-gain photoconductor receiver. The difference in gray-scale value between the background and contrast medium was calculated. Images were evaluated by counting of arteries. RESULTS The difference in contrast at low levels was detected with the high-gain photoconductor receiver but not with the charge-coupled device camera. The photon density of synchrotron radiation with the high-gain photoconductor receiver was one-fifth that with the charge-coupled device camera. The high-gain photoconductor receiver had approximately 5 times the sensitivity of the charge-coupled device camera. CONCLUSION Use of the synchrotron radiation and high-gain photoconductor receiver makes it possible to perform angiography with an extremely low concentration of contrast medium.

Development of FOP-HARP imaging device

The high-gain avalanche rushing amorphous photoconductor (HARP) camera tube achieves ultrahigh-sensitivity by using the avalanche multiplication. The applications of this tube extend beyond broadcasting into other fields. It is attracting a great deal of attention especially for radiation diagnosis, such as synchrotron radiation microangiography, because it can obtain high-resolution and high-contrast images with a low dose of radiation. However, in the present system, a fluorescent screen and the photoconductive film of the HARP tube are connected optically by a lens-coupling method, and low light throughput remains a big problem. To improve the light throughput by using a fiber-coupling method, we applied a fiber-optic plate (FOP) to the substrate of a HARP tube. The FOP consists of three types of glass that have differing hardnesses and elastic coefficients that make it difficult to flatten the FOP surface enough to form the HARP film. We thus introduced a new mechanical polishing method and succeeded in realizing avalanche multiplication in the FOP-HARP tube. The results of shooting experiments by applying the FOP-HARP to the microangiography showed that a spatial resolution of over 20 line pairs/mm was obtained. Moreover, rat femoral arteries of 150-200 μm in diameter could be visualized as motion pictures with a one-fourth lower concentration of contrast material than that needed for ordinary microangiography. Another potential application of the FOP-HARP is an ultrahigh-sensitivity nearinfrared (NIR) image sensor made by fiber-coupling with an image intensifier (I.I.). The image sensor provides highquality images and should be a powerful tool for NIR imaging.

A new technique of in vivo synchrotron radiation coronary microangiography in the rat

Background Previously, in our laboratory, synchrotron radiation coronary microangiography (SRCA) using Langendorff-perfused rat hearts could visualize a coronary artery of 50 µm in diameter. However, in vivo rat SRCA poses the problem of compromised temporal resolution due to the rapid heart rate of rats. Purpose To establish a simple method of in vivo rat SRCA with bradycardia induced by intravenous injection of adenosine triphosphate disodium hydrate (ATP). Material and Methods SRCA was performed at the Photon Factory of the High Energy Accelerator Research Organization (Tsukuba, Japan). Eight male Wistar rats were anesthetized. A catheter for injecting the contrast material was inserted into the carotid artery. Temporary bradycardia was induced by an intravenous bolus injection of 5 mg of ATP, and SRCA was performed immediately thereafter. Results After ATP administration, the average heart rate decreased from 388 to 73 beats per minute. As a result, we could detect a coronary artery as small as 45 µm in diameter. Conclusion Our SRCA system which has a high resolution of 9 µm per pixel could detect a coronary artery as small as 45 µm in diameter in the in vivo rat.

Using synchrotron radiation angiography with a highly sensitive detector to identify impaired peripheral perfusion in rat pulmonary emphysema

Synchrotron radiation angiography with a HARP detector made it possible to evaluate impaired pulmonary microcirculation in pulmonary emphysema by means of high sensitivity.

Giant coronary artery aneurysm with pulmonary artery fistula in a patient on chronic hemodialysis.

The combination of coronary artery aneurysm and pulmonary artery fistula is extremely rare and its common cause is atherosclerosis. A 61-year-old woman presented with a giant coronary artery aneurysm with pulmonary artery fistula and intramyocardial calcifications of the left ventricle associated with progressive atherosclerosis due to chronic hemodialysis. The coronary artery aneurysm was resected under cardiopulmonary bypass because of hemodynamic instability due to restrictive cardiac dysfunction. The patients restrictive cardiac dysfunction was improved after aneurysm resection. Surgical resection should be considered for giant coronary artery aneurysm with restrictive cardiac dysfunction.

Renal contrast microangiography with synchrotron radiation: a novel method for visualizing structures within nephrons in vivo

Background No non-invasive method of observing renal microcirculation in vivo has been established as yet. Although angiography is considered to be ideally suited for the purpose, conventional X-rays cannot be used to image structures smaller than 100 µm. Purpose To develop a method for visualizing the renal arterioles, glomeruli, and proximal tubules of rats in vivo making use of synchrotron radiation. Material and Methods Male Wistar rats were anesthetized, and a catheter was inserted via laparotomy into the abdominal aorta with its tip placed above the renal arteries. The rats were paralyzed with a neuromuscular blocking agent and mechanically ventilated. An inorganic iodine contrast medium was injected via the catheter. The SR derived X-rays transmitted through the subjects were recorded with a CCD camera. Two-dimensional images with a pixel size of 9 µm were obtained. The exposure time was fixed at 50 ms, with a maximum acquisition rate of three images/s. Results Renal arterioles as small as 18 µm in diameter, glomeruli with an average diameter of 173 ± 21 µm, as well as proximal tubules, were clearly visualized. In addition, glomerular density at the peripheral renal cortex was measurable. Conclusion Rat renal microcirculation could be successfully observed in real-time, without exteriorization of the kidney in this study.

Nontraditional placement of an implantable cardioverter-defibrillator in a heterotaxy patient after the completion of total cavopulmonary connection

A 15-year-old boy with heterotaxy syndrome developed a prolonged QT interval and intractable torsade de pointes after the administration of sodium channel blockers for atrial tachyarrhythmia. Although this situation called for the placement of an implantable cardioverter-defibrillator, a conventional transvenous approach was not available since the patient had previously undergone a nonfenestrated extracardiac total cavopulmonary connection. We were urged to carry out the surgical placement of an epicardial lead for an implantable cardioverter-defibrillator using a single coil transvenous shock lead through re-do midline sternotomy. Here we describe the details of this nontraditional surgical procedure for the placement of a lead for an implantable cardioverter-defibrillator in a case without venous access into the heart.