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Biomedical subjects

Kazumasa Orihashi

Publications and source records attributed to Kazumasa Orihashi.

At least 19 recordsLinked to original sources
PubMed2006

Intra-aortic injection of propofol prevents spinal cord injury during aortic surgery.

OBJECTIVE: We investigated whether propofol, a widely used anesthetic, injected into clamped aortic segments quickly attenuated transcranial spinal motor-evoked potential (MEP) amplitudes and protected against spinal cord injury during thoracoabdominal aortic surgery. METHODS: Eighteen beagle dogs were divided into three groups (n=6, each group): group 1 (20 ml of saline, intra-aortic injection), group 2 (1.5 mg/kg of propofol, intravenous injection), and group 3 (1.5 mg/kg of propofol, intra-aortic injection). Aortic cross-clamping was performed for 30 min. In each group, MEP amplitudes were recorded before, during, and after aortic cross-clamping. Tarlov score and histopathological examination were used to evaluate the protective effects of intra-aortic propofol injections. RESULTS: MEP amplitudes in group 3 attenuated to a value that was 60% of the control in just a minute after aortic cross-clamping, but maintained 40% of the control value during aortic cross-clamping. However, MEP amplitudes in groups 1 and 2 gradually attenuated and almost disappeared. Groups 1 and 2 amplitudes were lower than those in group 3, 30 min after aortic cross-clamping (p<0.001). Twenty-four hours after ischemia, the Tarlov score in group 3 was 3.5+/-0.5 and was higher than scores from groups 1 and 2, which were 0.5+/-0.5 and 1.3+/-1.2 (mean+/-SD, p<0.001, and p<0.001), respectively. Histopathologically, normal spinal cord motor neurons in group 3 were preserved to a significantly greater extent than in groups 1 and 2 (p=0.0031, and p=0.0282, respectively). There was a strong correlation between Tarlov scores at 24h and the number of normal motor neurons in the anterior horns of spinal cords (r=0.897; p<0.001). CONCLUSIONS: Intra-aortic propofol injections produce the quick suppression of MEP amplitudes and protect spinal cords from ischemia during aortic cross-clamping.

Animals↗
PubMed2006

Cold spinoplegia and transvertebral cooling pad reduce spinal cord injury during thoracoabdominal aortic surgery.

OBJECTIVE: We examined the protective effects of the new selective spinal cord cooling by using cold saline infusion into the cross-clamped aorta and a transvertebral cooling pad placed over the lumbar vertebral column from paraplegia caused by ischemic spinal cord injury on thoracoabdominal aortic surgery. METHODS: Eighteen rabbits were divided into three groups: groups I, II, and III (n = 6 for each group). In group I (37 degrees C; 5 mL) and group II (3 degrees C; 5 mL), saline was infused into the isolated aortic segment twice, at 0 and 5 minutes after aortic cross clamping. In group III, a 3 degrees C saline solution plus cooling pads placed just after cross clamping were combined. The infrarenal aorta was then isolated proximally and distally by vascular clamps for 12 minutes. In our preliminary study, only the abdominal aorta just distal to the left renal artery was clamped. At 48 hours after reperfusion, the groups clamped for 12 and 15 minutes were all paraplegic. The time of clamping the aorta was set at 12 minutes as the critical point when paraplegia occurred upon simple clamping of the infrarenal aorta only. The spinal cord temperature was monitored at the L4 level continuously during the procedures in all three groups. At 8, 24, and 48 hours after the operation, hind limb function was estimated by using the Tarlov score, which is often used for evaluating motor function in animals. A histopathologic study using hematoxylin and eosin stains was also performed. RESULTS: At 48 hours after the operation, the Tarlov scores in groups I, II, and III were 0 +/- 0, 2.0 +/- 1.9, and 4.0 +/- 0 (mean +/- SD), respectively. The Tarlov score and histopathologic analysis in group III were significantly superior to those of groups I (P < .01) and II (P < .05). The spinal cord temperature in groups II and III decreased by -1.8 degrees C and -4.3 degrees C at its minimum. The rabbits in group III were also protected from paraplegia. CONCLUSIONS: Selective spinal cord cooling with cold saline infusion into the isolated aortic segment and transvertebral regional cooling can reduce the neurologic damage of spinal cord ischemia.

Animals↗
PubMed2006

Traumatic subarachnoid hemorrhage visualized with transesophageal echocardiography.

Computed tomography (CT) is the current standard for the early diagnosis of traumatic subarachnoid hemorrhage (tSAH). It is, however, not feasible when a patient is hemodynamically unstable. We report a novel method of visualizing tSAH with transesophageal echocardiography (TEE). The spinal cord was visualized through the intervertebral disc with the transducer directed posteriorly in the esophagus. TEE findings of the spinal cord in three patients with tSAH were compared with those of 19 patients without it. In the former, fibrin-like mobile images were present, the ratio of diameter of spinal cord to internal diameter of spinal canal was significantly larger (0.59 +/- 0.07 vs. 0.45 +/- 0.04, p = 0.0070) and the pia mater was significantly thicker (1.41 +/- 0.12 mm vs. 0.66 +/- 0.15 mm, p = 0.0001). Our findings suggest that TEE may be an alternative way of diagnosing early tSAH at bedside in patients in which CT is not feasible.

Contraindications↗
PubMed2006

Detection and monitoring of complications associated with femoral or axillary arterial cannulation for surgical repair of aortic dissection.

OBJECTIVES: Femoral arterial perfusion can be associated with complications, and axillary arterial perfusion is not free from risk. The purpose of this study was to describe the incidence and complications of femoral versus axillary artery cannulation for surgical repair of aortic dissection and to devise a strategy for early detection and monitoring of complications using transesophageal echocardiography, near-infrared spectroscopy, and orbital Doppler. DESIGN: Retrospective and observational. SETTING: University hospital. PARTICIPANTS: Seventy-five consecutive patients with aortic dissection who underwent aortic repair between 1995 and 2004. INTERVENTIONS: Aortic surgery. MEASUREMENTS AND MAIN RESULTS: Among the 44 cases with femoral arterial perfusion, sudden onset of hypotension occurred in 3 cases but was immediately treated based on the TEE diagnosis (collapse of true lumen in the descending aorta). In another case, myocardial ischemia occurred because of occlusion of the coronary artery. These four cases comprised 57.1% of 7 patients with type III dissection with retrograde extension in whom femoral arterial perfusion was used. However, malperfusion was not encountered in 3 cases of the same type of dissection but with axillary arterial perfusion. Axillary artery perfusion (29 cases) led to malperfusion of the right frontal lobe and coronary artery in 1 case each. CONCLUSIONS: Flexible management guided by real-time information is essential. Upon initiating femoral arterial perfusion, malperfusion should first be checked for in the descending aorta and then in the coronary and visceral arteries, especially in cases of type III dissection with retrograde extension. Attention should be paid to cerebral and coronary malperfusion when initiating axillary arterial perfusion.

Adult↗
PubMed2006

An alternative for descending thoracic aortic aneurysm repair.

A simple technique termed "clamp test and spinal cord-plegia" for descending thoracic aortic aneurysm surgery is described. The clamp test is a passive method of creating ischemic conditions, whereas spinal cord-plegia is an active method of decreasing metabolism. This technique is a practical test that double-checks for critical feeding arteries and seems to have an excellent spinal cord-preserving effect.

Aged↗
PubMed2006

Evoked spinal cord potentials monitored at thoracoabdominal region after trans-intercostal stimulation.

To investigate the feasibility of a novel recording method for trans-intercostal evoked spinal cord potentials (Tic-ESCPs) and the properties of the waveforms, the potentials were recorded and analyzed in an animal model. In two beagle dogs, Tic-ESCPs were recorded at the left twelfth intercostal to fourth lumbar nerves following stimulation at the left eleventh intercostal nerve, either with or without the use of a muscle relaxant. The amplitude and latency of the Tic-ESCP waves were then measured and compared with those of conventional transcranial spinal motor evoked potentials (MEPs). Tic-ESCPs could be obtained at any nerve, with or without the use of a muscle relaxant. The Tic-ESCP waveform was clear and simple, consisting of a small positive (P1) wave and a subsequent large negative (N1) wave. As the site of recording moved farther from the stimulation site, the N1 amplitudes were reduced and the P1 latency was prolonged. Under muscle relaxation, the N1 amplitudes were reduced, and the P1 latencies were shorter. As compared with MEPs, Tic-ESCPs could be evoked by a weaker stimulus, the N1 amplitude was smaller, and the P1 latency was shorter. Tic-ESCP recording was feasible either with or without the use of a muscle relaxant. The Tic-ESCPs showed simple and clear waveforms with smaller stimulations. Therefore, Tic-ESCPs may be useful for intraoperative spinal cord monitoring.

Abdomen↗
PubMed2005

Perioperative diagnosis of mesenteric ischemia in acute aortic dissection by transesophageal echocardiography.

OBJECTIVE: Although computed tomography, angiography, or magnetic resonance imaging is most commonly used for diagnosing mesenteric ischemia caused by acute aortic dissection, use of these modalities is often limited in the perioperative period. Thus, we have introduced transesophageal echocardiography to cover this deficit. Purpose of this study is to report the feasibility and accuracy of transesophageal echocardiographic diagnosis on mesenteric ischemia. METHODS: The consecutive 24 cases with acute aortic dissection which involved abdominal aorta and underwent surgery were examined. The celiac artery and superior mesenteric artery was visualized with 5 MHz biplane transesophageal echocardiography and was assessed for presence of dissection and blood flow in each of true and false lumen. The transesophageal echocardiographic findings were then correlated to the clinical course, computed tomographic findings, and laboratory data. RESULTS: The celiac artery and superior mesenteric artery was successfully visualized in 24 cases (100%) and 23 cases (95.8%), respectively. Perfusion patterns in superior mesenteric artery were categorized into four patterns: (1) intact artery with adequate perfusion (type A: 14 cases); (2) dissection in the artery but with adequate perfusion in true lumen (type B: 5 cases); (3) dissection in the artery with narrowed true lumen compressed by false lumen without detectable blood flow (type C: 1 case); and (4) obstruction of arterial orifice by the intimal flap with narrowed true lumen in the proximal aorta (type D: 2 cases). One case with immediate postoperative death and another case with unsuccessful visualization of superior mesenteric artery were excluded from the analysis. Clinically apparent intestinal ischemia was present in three cases: one case with type C and two cases with type D, but in none of the remaining 19 cases with type A or type B (both sensitivity and specificity were 100%). The superior mesenteric artery was opacified in all of these three cases with ischemia. CONCLUSIONS: The transesophageal echocardiographic assessment is feasible in nearly all patients and potentially provides correct diagnosis on intestinal ischemia in the perioperative period of acute aortic dissection. Types C and D indicate significant mesenteric malperfusion.

Acute Disease↗
PubMed2005

Left internal thoracic artery graft assessed by means of intraoperative transesophageal echocardiography.

BACKGROUND: We report a method of intraoperative assessment of left internal thoracic artery (LITA) graft with transesophageal echocardiography regarding patency, stenosis, and presence of remnant branch artery. METHODS: In 52 consecutive coronary artery bypass grafting surgery patients, blood flow velocity was measured at the origin of the LITA after coronary artery bypass grafting by means of transesophageal echocardiography. The flow pattern and velocity change at temporary clamping of the graft was examined and was compared with the postoperative angiographic findings. RESULTS: The LITA was visualized in 47 of 52 cases (90.4%). The LITA flow was diastolic dominant, systolic dominant, or equivalent in 41, 3, and 3 cases, respectively. The anastomosis was stenotic in 2 of 6 cases of the latter two groups, but in none of the 41 cases with diastolic dominant flow (p = 0.0139). The branch artery was present in 4 of 6 cases of the latter two groups, but in only 2 of 41 cases with diastolic dominant flow (p = 0.0012). Remnant branch artery was found in all three cases with systolic dominant flow. The LITA flow was instantaneously reduced at clamping and recovered at declamping in every case with graft occlusion but one. The ratio of velocity change at clamping was less than 0.50 in all 41 cases without remnant branch, whereas it was more than 0.50 in 5 of 6 cases with a branch (p < 0.0001). CONCLUSIONS: The transesophageal echocardiographic assessment with the clamp test is feasible intraoperatively in the majority of patients, enabling us to assess LITA graft patency, stenosis, or presence of a remnant branch.

Adult↗
PubMed2005

Midterm results of pulmonary vein isolation for the elimination of chronic atrial fibrillation.

BACKGROUND: This study aims to clarify midterm results of chronic atrial fibrillation elimination after pulmonary vein isolation and provides an evaluation of factors influencing results. METHODS: Forty-nine patients were enrolled in this study. We performed a simple pulmonary vein isolation with the aid of cryoablation or radiofrequency ablation directed towards the left posterior remnant of the posterior left atrium. Results were evaluated using elimination rates of atrial fibrillation during the postoperative follow-up for > 12 months. We also examined factors influencing the recurrence of atrial fibrillation. RESULTS: There were no hospital deaths or serious complications among the 49 patients. The total follow-up duration was 137.2 patient years. Forty-seven patients (96%) were followed with serial consultations, but 2 patients were dropped from this study because of changes in residence. Thirty-five of 49 patients (71.4%) showed regular sinus or nodal rhythms at discharge. In 4 patients atrial fibrillation recurred during the follow-up period, whereas in another 4 patients sinus rhythm was restored, although they showed atrial fibrillation at discharge. The cumulative elimination rate was 70.2% (33 of 47 patients), which was determined at the last follow-up period. Large left atrial diameters, a long history of atrial fibrillation, and low-voltage fibrillatory waves in V1 leads were preoperative indicators of recurrence of atrial fibrillation. CONCLUSIONS: Pulmonary vein isolations were effective in the treatment of chronic atrial fibrillation patients and sinus rhythms were restored within the follow-up period.

Adult↗
PubMed2005

Newly developed aortic dissection in the abdominal aorta after femoral arterial perfusion.

BACKGROUND: Aortic dissection after femoral arterial perfusion has been reported as a dreadful complication. Apart from such a drastic event, using intraoperative transesophageal echocardiography we detected aortic dissection confined to the abdominal aorta that was associated with visceral malperfusion. METHODS: We examined 11 consecutive patients with aortic dissection in whom the abdominal aorta was intact, and surgeries were performed with femoral perfusion. The abdominal aorta and visceral branches were examined for new development of dissection or malperfusion by means of transesophageal echocardiography before, during, and after cardiopulmonary bypass. These echocardiographic findings were then related to the postoperative assessment and midterm results. RESULTS: Aortic dissection was found in 3 of 11 cases (27.2%). Unusual progression of metabolic acidosis (base excess < or =10 mEq/L) occurred, possibly as a result of malperfusion of visceral arteries, in 2 of these 3 cases, whereas none of the 8 cases presented with such findings. The presence of dissection was later confirmed by postoperative computed tomography in all but 1 case. In the midterm follow-up period, aneurysm formation was found in the infrarenal aorta and iliac arteries in 2 of the 3 cases with new aortic dissection but not in any of the remaining 8 cases. CONCLUSIONS: New development of aortic dissection after femoral arterial perfusion was found in 27% of the cases in this series. Although these occurred without dramatic symptoms, this event may be related to unusual metabolic acidosis during cardiopulmonary bypass or to subsequent aneurysmal formation of the infrarenal aorta or iliac arteries, or both.

Acidosis↗
PubMed2005

Thrombosed arch vessels after cardiac arrest because of pulmonary embolism.

An unusual case of thrombus formation in the arch vessels after cardiac arrest because of pulmonary embolism is reported. A 67-year-old woman developed pulmonary embolism that soon led to cardiac arrest. Although percutaneous cardiopulmonary support was started, the blood pressure of her upper extremity was below 20 mm Hg and blood gas analysis showed marked metabolic and respiratory acidosis. Transesophageal echocardiography revealed thrombus in the right pulmonary artery, thrombus with floppy movement in the aortic arch, and 3 arch branch arteries filled with thrombus with little blood flow around it. After thrombolytic therapy, the thrombi gradually shrunk and perfusion in the upper extremities improved. The patient was successfully weaned from percutaneous cardiopulmonary support and was discharged alive. Thrombus formation can occur in the arch branch arteries after cardiac arrest, causing unusual laboratory data. Transesophageal echocardiography is useful for obtaining real-time information in the cardiovascular system at bedside in such a critically ill patient.

Aged↗
PubMed2005

Malposition of selective cerebral perfusion catheter is not a rare event.

OBJECTIVE: Although malposition of a catheter for selective cerebral perfusion can lead to postoperative neurologic complications, the clinical relevance or even an incidence of this event is not clear because there have been no measures to diagnose it. The purpose of this study is to report the results of intraoperative diagnosis of catheter malposition by means of near-infrared spectroscopy, orbital ultrasound, and transesophageal echocardiography. METHODS: The 35 consecutive patients of aortic arch aneurysm undergoing total arch replacement (13 patients) or transaortic stent graft implantation (22 patients) were examined. The regional oxygen saturation in the frontal lobe was continuously monitored with near-infrared spectroscopy. When cerebral malperfusion was suspected with saturation drop and reduced blood flow in orbital ultrasound, blood flow in the cervical branches and catheter position were examined with transesophageal echocardiography. RESULTS: Catheter malposition was detected in 4 of 35 cases (11.4%). The echo findings included: (1) reduced or absent flow and/or collapsed lumen in the common carotid artery despite an adequate perfusion rate; and (2) the balloon of catheter blocking the inflow to the common carotid artery. There was no unusual changes in parameters of other conventional monitors. After the catheter was withdrawn (three cases) or replaced (one case) based on the above diagnosis, cerebral perfusion was restored, confirmed by these three modalities. An accidental entry of catheter into the right common carotid artery was detected by transesophageal echocardiography in one case, in which there was no abnormal finding of oxygen saturation or orbital blood flow. CONCLUSIONS: Catheter malposition on the right side is not a rare event during selective cerebral perfusion. The catheter can migrate into the right subclavian artery or common carotid artery. Pressure monitoring cannot reliably detect an occurrence of catheter migration into the right subclavian artery. Combined use of near-infrared spectroscopy, orbital ultrasound, and transesophageal echocardiography can be useful for detecting this event and making an appropriate decision without delay to prevent irreversible brain damage.

Aged↗
PubMed2005

Extrathoracic subclavian venipuncture under ultrasound guidance.

BACKGROUND: Cardiac pacemaker and defibrillator leads are inserted through extrathoracic subclavian venipuncture using ultrasound (US) guidance, but there can be complications. The purpose of this study was to investigate a safer and improved implanting procedure. METHODS AND RESULTS: Venipuncture guided by US with a 7.5 MHz convex transducer was performed to implant 32 leads in 18 patients. US enabled identification and location of the vein and needle tip during puncture and clarified the reasons for unsuccessful venipuncture. Venipuncture was successful on the second attempt or within 2 min in 90.6% (29/32) and 84.4% (27/32) of lead placements, respectively, although the vein was small (mean, 7.8 mm), deep (mean, 22.7 mm), and required a large angle of entry (mean, 52.4). The subclavian artery or lung was adjacent to the vein in 50.0% and 27.8% of cases, respectively. The flexible wall of the vein interfered with the penetration of the needle in 33.3% of cases. It was often difficult to locate the needle tip because of poor visualization. CONCLUSIONS: Ultrasound guidance of subclavian venipuncture enables a safe and time-saving procedure by visualizing not only the needle but also the vein and surrounding structures, although further modifications of the needle are needed for better visualization.

Defibrillators, Implantable↗
PubMed2005

Novel Doppler technique to assess systemic vascular resistance: the snuffbox technique.

BACKGROUND: To explore an alternative to the systemic vascular resistance index (SVRI) for monitoring peripheral circulation in patients in the intensive care unit (ICU), the resistive index (RI) in the upper extremity arteries was measured by using surface Doppler ultrasound. METHODS AND RESULTS: The correlation between RI and vascular resistance was assessed in vitro using a vessel phantom in a Donovan-type mock circulation system. In addition, 15 ICU patients who had undergone open-heart surgery were studied. Mean arterial pressure, central venous pressure and cardiac output were measured 30 times at 10 min intervals after patients returned to the ICU following surgery, and the SVRI was calculated from these parameters. At the same time points, 3 parts of the upper extremity arteries (brachial artery in the cubital fossa (BA), radial artery at the wrist (RA), and radial artery at the anatomical snuffbox (SB)) were scanned by Doppler ultrasound, and the resistance index (RI) for each artery region was calculated. In vitro, RI increased with higher vascular resistance, exhibiting a significant correlation (r = 0.982, p < 0.0001). In vivo, the average incidence angles at the BA and RA were larger than 60 degrees , while that at the SB was only 11.5+/-10.8 degrees. The overall correlation between SVRI and RI for all patients was not significant for the BA or RA, but was significant for the SB (p < 0.0001). In individual patients, the correlation of SVRI with RI at the BA or RA was significant in 3 patients only, whereas significant correlation for the SB was observed in all patients. Doppler waveform analysis at the SB revealed diastolic flow reversal with increased SVRI. CONCLUSIONS: Measurement at the SB provides an ideal ultrasound incidence angle for the measurement of blood flow velocity. Hence, RI measured in this way may serve as an indicator of peripheral vascular resistance, and may be effective for the evaluation of peripheral circulatory disturbance.

Aged↗
PubMed2005

Echo-guided identification of key lumbar arteries for the spinal cord: preliminary study in the canine model.

Although identification of the key artery that perfuses the spinal cord is essential to avoid occurrence of paraplegia after surgery on the thoracoabdominal aorta, reliable and noncomplicated measures are not yet available. A new method of determining it by using echocardiography with a saline injection into the lumbar artery was evaluated for feasibility and adequacy in a canine model. In two mongrel dogs, the abdominal aorta was opened and saline was directly injected into the lumbar arteries while the spinal cord was visualized by echocardiography through the intervertebral disc. When the echogenic or Doppler signal was detected in the spinal cord, the particular lumbar artery was determined as "positive", or as "negative" when the signal was not detected. After the dog was sacrificed, red resin was injected into the "positive" arteries and blue resin into the "negative" arteries. In the extracted spinal cord, the anterior and posterior spinal arteries were filled with red resin, rather than with blue resin, to indicate that the key arteries were correctly identified. There were multiple "positive" arteries, which were mainly located on the left side and accounted for approximately one-third of the entire lumbar arteries. The "negative" arteries mainly perfused the muscles around the vertebra. Injected resin came out of the adjacent lumbar arteries of the same category, suggesting that communication is present among the positive arteries, but independently of that among the negative arteries. Echo-guided identification of key arteries is technically feasible and correctly determines the key arteries in this preliminary canine model.

Animals↗