PubMed Health⌕ Search

Biomedical subjects

Katsuhiko Imai

Publications and source records attributed to Katsuhiko Imai.

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

Right gastroepiploic artery grafting for saphenous vein graft pseudoaneurysm.

Saphenous vein graft pseudoaneurysms are an unusual but potentially fatal complication of coronary artery bypass grafting because of their high risk of rupture or thromboembolism. We experienced the case of a 58-year-old man with a saphenous vein graft pseudoaneurysm with a floating thrombus that had developed 17 years after the initial coronary artery bypass grafting. The prevention of thromboembolism during a surgical procedure has been crucial for this type of operation. We developed the idea of in situ revascularization using the right gastroepiploic artery under the beating heart on cardiopulmonary bypass followed by an aneurysmectomy under an arrested heart.

Aneurysm, False↗
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↗
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↗
PubMed2004

Successful coil embolization for spontaneous arterial rupture in association with Ehlers-Danlos syndrome type IV: report of a case.

When a patient with Ehlers-Danlos syndrome (EDS) presents with a vascular emergency, performing life-saving surgery can be difficult because of the profound fragility of the arterial tissue. We report the case of a 27-year-old woman with EDS in whom a spontaneous arterial rupture was successfully treated with transcatheter embolization. The patient was brought to our hospital in shock, with left lower abdominal pain. She had been diagnosed with EDS type IV following a colonic rupture 8 years earlier. An emergency angiogram revealed rupture of the left external iliac artery. The active bleeding was managed by transarterial embolization of the ruptured artery using stainless steel coils, which took 30 min to achieve. The patient has not suffered any further vascular complications during the year since this procedure. Transcatheter coil embolization may be a reliable option for treating sudden arterial rupture in patients with this syndrome.

Adult↗
PubMed2004

Successful shrinkage of distal arch and proximal descending aortic aneurysm after transaortic endovascular stent-grafting.

OBJECTIVES: Although endovascular stent-grafting is available for atherosclerotic thoracic aneurysms, it is unknown whether the excluded thrombosed aneurysms shrink. We evaluated serial changes in distal aortic arch or proximal descending aortic aneurysms excluded space after transaortic stent-grafting. METHODS: Thirty-four patients with true distal aortic arch or proximal descending thoracic aortic aneurysms were treated by stent-grafts introduced via proximal arch aortic incisions. Follow-up included computed tomographs (CT) every 6 months in 31 patients. The maximum dimensions for excluded space and aneurysmal diameters were measured and evaluated to determine whether the aneurysmal space had decreased or shrunken following this alternative procedure. RESULTS: Two hospital deaths (5.9%) were caused by a cerebral embolism and a peri-operative myocardial infarction. Another case died from pneumonia a year after surgery. Thirty-one cases (91%) survived during follow-up, but one case suffered from paraplegia (2.9%). The follow-up period ranged from 10 to 72 months (average 39.3+/-27.2 months). There were no aneurysmal ruptures during follow-up. Post-operative serial CTs showed a disappearance or a significant shrinkage of the excluded aneurysmal space in 30 of the 31 cases (97%); one case suffered endoluminal leakage. CONCLUSIONS: Transaortic endovascular stent-grafting is feasible for distal aortic arch or proximal descending aortic aneurysms. The excluded aneurysmal space disappears or shrinks after successful stent-graft placement.

Aged↗
PubMed2004

Early type A dissection with the aortic connector device.

A 75-year-old woman who had suffered type B dissection had coronary artery bypass grafting surgery using a mechanical aortic connector. Four days after the operation, she had a sudden syncope. CT demonstrated type A dissection, and an emergency operation was done, and postoperative course was uneventful. This case demonstrates that this connector should be used carefully in patients with a history of type B dissection.

Aged↗
PubMed2004

Near-infrared spectroscopy for monitoring cerebral ischemia during selective cerebral perfusion.

OBJECTIVE: To minimize the neurological complications following cardiovascular surgery, it is essential to prevent an occurrence of cerebrovascular embolism and to detect and solve cerebral malperfusion without delay in the operating theater. Although we have introduced near-infrared spectroscopy (NIRS) monitoring for the purpose of detecting cerebral malperfusion, no criterion has been available. We searched for this criterion by examining the relationship of sustained drop in the regional oxygen saturation (rSO2) of the frontal lobes to the occurrence of neurological events. METHODS: The 59 consecutive patients undergoing aortic surgery with selective cerebral perfusion (SCP) were examined. The rSO2 was monitored throughout the surgery and the durations of drops in rSO2 to below 55% and those below 60% were determined for each patient. The durations of rSO2 drop and other surgery-related parameters were compared between the patients in whom neurological events occurred and those without such events. RESULTS: A total of 16 cases (27.1%) presented with neurological events. Newly developed cerebral infarction was documented in 6 of these 16 cases. Operation time and the durations for which rSO2 dropped were significantly longer for the 16 patients with neurological events than for the 43 patients without events (Op time: 546.8 versus 448.1 min, P=0.0064; rSO2 below 60%: 141.2 versus 49.8 min, P=0.0032; rSO2 below 55%: 66.6 versus 10.6 min, P=0.0011), while there was no significant difference in age, bypass time, aortic clamping time, SCP time, and circulatory arrest time between the two groups. In the 3 patients with infarcts suggestive to hypoperfusion, sustained decrease in rSO2 was observed, while it was not significant in the remaining 3 patients with infarcts suggestive to embolism. Among the 53 patients without infarction, transient neurological events occurred more frequently in patients with sustained drop in rSO2 below 55% for over 5 min (44.4% versus 5.7%, P=0.0014). CONCLUSIONS: A sustained drop in rSO2 during aortic surgery is closely related to the occurrence of neurological events following surgery. We recommend that recovery of drop in rSO2 below 55% should be addressed without delay. However, use of NIRS is limited for detecting embolic events or hypoperfusion in the basilar region.

Adult↗