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Biomedical subjects

R Yozu

Publications and source records attributed to R Yozu.

At least 19 recordsLinked to original sources
PubMed2003

[The role of staged Fontan operation on early and long-term outcome].

Of 185 patients with single ventricle physiology, 59 patients who underwent Fontan type operations between April 1970 and May 2002 served as subjects. Subjects displayed a median age of 5.2 years and a median body weight of 11.4 kg. In the first 22 years (group 1), 34 patients underwent concomitant right atrium-pulmonary artery (RA-PA) anastomosis, Björk procedure and total cavopulmonary connection (TCPC), while in the last 8 years (group 2), 25 patients underwent staged TCPC, where bidirectional cavopulmonary shunt (BCPS) and obliteration of additional pulmonary blood flow was performed previously. Four cases of early death (group 1:4 patients, group 2:0 patient) and 12 cases of late death (group 1:11 patients, group 2:1 patient) were encountered. Early mortality was 6.8% (group 1:12%, group 2:0%, p = 0.10) and late mortality was 21%. The 5-year survival rate was 85.2 +/- 4.9% (group 1:80.0 +/- 6.8%, group 2:93.8 +/- 6.1%, p = NS), and the 10-year survival rate was 79.6 +/- 6.0%. Staged TCPC, precedent BCPS with obliteration of additional pulmonary blood flow, seems to be beneficial for accurate patient selection for Fontan candidate.

Adolescent↗
PubMed2001

Optimal positioning of temporary epicardial atrial pacing leads after cardiac surgery.

OBJECTIVES: Atrial pacing plays an important role in preventing low output syndrome and arrhythmia after cardiac surgery. We studied the optimal positioning for temporary epicardiac atrial pacing. METHODS: The performance of temporary epicardiac atrial pacing leads was examined after 13 cases of elective coronary artery bypass grafting between October 1999 and January 2000. Two bipolar electrode leads were used--1 on the cephalic atrial wall between the left and right atrial appendages, where the Bachmann bundle indwells (site A), and the other on the interatrial groove (site B). To assess pacing performance on postoperative days 1, 2, and 7, we measured 3 pacing patterns--bipolar use of sites A and B leads, and combined use of the 2 with the site A lead acting as the negative electrode and the site B lead as the ground. The pacing threshold was measured at a 0.5 ms pulse width, using the P wave amplitude and slew rate as indicators of sensing performance. RESULTS: Bipolar pacing both at sites A and A-B was superior to that at site B in pacing threshold and sensing parameters. CONCLUSIONS: The negative electrode at site A is mandatory for high atrial pacing and sensing performance.

Cardiac Pacing, Artificial↗
PubMed2001

Port-access cardiac surgery. Experience with 34 cases at Keio University Hospital.

OBJECTIVES: We reviewed our experience with port-access cardiac surgery and evaluated the medical effects and benefits of this technique in view of postoperative quality of life and medical expenses incurred during hospitalization. METHODS: From June 1998 to August 2000, port-access cardiac surgery was conducted on 34 patients--22 with atrial septal defect, 6 with mitral regurgitation, 2 with coronary artery disease, 2 with partial endocardial cushion defect, 1 with ventricular septal defect, and 1 with atrial and ventricular septal defects. Two types of endoaortic-balloon catheters were used to execute aortic cross-clamping. Skin incisions were 5 cm long. RESULTS: No hospital or late deaths were observed. Patients with atrial septal defect were discharged on postoperative day 3.7, patients of mitral regurgitation on postoperative day 4.2, and patient of ventricular septal defect on postoperative day 4.0 on the average. None were readmitted. Patients appeared undisturbed by early discharge and were able to resume physical work on day 22 on the average after discharge. CONCLUSION: Patients undergoing port-access cardiac surgery recovered quickly from surgery and resumed work quickly. This technique thus proved satisfactory both physically and mentally to patients and improved their quality of life. Medically and economically this technique proved extremely beneficial. We confirmed it to constitute a viable approach and option for cardiac surgery in selected patients.

Adolescent↗
PubMed2001

Detection and management of concomitant coronary artery disease in patients undergoing thoracic aortic surgery.

OBJECTIVES: No method has been established to detect and manage coronary artery disease in patients undergoing thoracic aortic surgery. METHODS: Subjects were 192 patients scheduled for elective thoracic aortic surgery. Selection criteria for coronary angiography included a history of coronary artery disease or a positive dipyridamole myocardial perfusion imaging test. RESULTS: Four patients were inoperable due to complications associated with coronary angiography or aneurysm rupture following coronary revascularization. A total of 55 patients with coronary angiography (group A) underwent 57 thoracic aortic operations and 133 patients without coronary angiography (group B) underwent 143 similar operations. Of 13 group A patients with significant coronary stenosis, 9 underwent either preoperative percutaneous transluminal coronary angioplasty (n = 3) or concomitant coronary artery bypass (n = 6). Perioperative myocardial infarction occurred in 3 group A patients (5%) and in 4 group B patients (1%, ns). The incidence of cardiac events--perioperative myocardial infarction or cardiac death--in group A (11%, 6/57) was higher than that in group B (3%, 4/143; p < 0.05). Multivariate analysis demonstrated incomplete revascularization of major coronary arteries with significant stenosis as a risk factor for cardiac events (p = 0.0106). CONCLUSIONS: Although dipyridamole myocardial perfusion imaging was useful, additional selection criteria for coronary angiography is needed. Complete revascularization of major coronary arteries with significant stenosis is essential to reduce postoperative cardiac events.

Adolescent↗
PubMed2001

Sinus node function after mitral valve surgery using the superior septal approach.

UNLABELLED: BACKGROUND; Sinus node function after the superior septal approach (SSA) in mitral valve surgery is controversial. We assessed sinus node function after this approach based on electrophysiological examinations and electrocardiographic change. METHODS: Forty-six patients underwent successful mitral valve surgery via the SSA. Preoperatively, 25 patients were in atrial fibrillation (AF), 20 were in normal sinus rhythm (SR), and 1 patient was paced. Thirteen patients who demonstrated no sinus node dysfunction preoperatively underwent postoperative electrophysiological studies. Peripostoperative cardiac rhythm was monitored using a portable four-lead electrocardiograph, and late cardiac rhythm was examined using standard 12-lead electrocardiography in the outpatient clinic. RESULTS: Twelve of 20 patients with preoperative SR experienced early postoperative supraventricular arrhythmias, but all spontaneously recovered SR. Electrophysiological studies revealed a basic cycle length of 767 +/- 74 ms, sinoatrial conduction time of 72 +/- 34 ms, sinus node recovery time of 1,119 +/- 139 ms, and corrected sinus node recovery time of 349 +/- 114 ms, thus demonstrating a lack of sinus node dysfunction. During the postoperative period (34 +/- 24 months), 2 of the 20 patients with preoperative SR developed persistent AF, and 3 of the 25 patients with preoperative AF achieved normal SR. CONCLUSIONS: The SSA does not appear to cause longterm adverse effects on sinus node function, although temporary effects may occur.

Adult↗
PubMed2001

Intraoperative assessment of coronary artery bypass graft: transit-time flowmetry versus angiography.

BACKGROUND: Transit-time flowmetry has been used to assess graft status intraoperatively. This study examines the validity of this method by comparing its results with the findings of simultaneously performed graft angiography. METHODS: The left internal thoracic artery (LITA) anastomosed to the left anterior descending artery (LAD) was assessed intraoperatively with both transit-time flowmetry and graft angiography in 30 patients. The patients were stratified into two groups based on intraoperative angiographic findings. In 18 patients (group A), the LITA and the LAD were well filled with contrast medium and the anastomosis was widely patent. In the other 12 patients (group B), spastic LITA or LAD was observed. Postoperative angiography was also performed before discharge from the hospital. RESULTS: The mean graft flow was 44.0 +/- 25.4 mL/min in group A and 23.4 +/- 10.0 mL/min in group B (p = 0.0129). Diastolic-dominant flow pattern was observed in both groups, and the ratio of peak diastolic flow to peak systolic flow and the percent diastolic time-flow integral were not statistically different between the groups. The pulsatility index was almost the same between the two groups and was acceptable in both. Postoperative angiography revealed that all grafts were patent without spasm or anastomotic stenosis. CONCLUSIONS: LITA graft status is satisfactory when high graft flow with diastolic dominance is obtained. When there is vasospasm but no anastomotic problems, decreased graft flow with an acceptable pulsatility index and diastolic augmentation is observed.

Angiography↗
PubMed2001

Free right internal thoracic artery as a second arterial conduit: modification of proximal anastomosis for improvement of graft patency.

The applicability of the right internal thoracic artery (RITA) for coronary artery bypass grafting is higher when used as a free graft than as a pedicled graft. However, the technical difficulty of directly connecting the proximal end of the free RITA to the much larger aorta leads to poor patency. To overcome this technical limitation, we have used a modification that places the proximal end of this artery onto the hood of an accompanying vein graft at the aortic anastomosis instead of directly onto the aorta. We performed isolated coronary artery bypass grafting on 43 patients using the free RITA as a second arterial graft following pedicled left internal thoracic artery grafting. The mean patient age was 60 years and 38 patients were male. There was no mortality and no incidence of morbidity related to free RITA use. Postoperative coronary angiography performed in all patients revealed that all proximal anastomoses were widely patent, making the patency rate of the free RITA 100%. With these encouraging results, the free RITA graft with the described modification is thought to be a more promising second arterial graft with greater versatility than the pedicled graft. The long-term evaluation of a large patient population will determine the significance of this modification.

Adolescent↗
PubMed2001

[Clinical experience in thoracoscopic left internal mammary artery harvesting with voice activated robotic assistance].

Between September 1998 to February 2000, 45 consecutive patients underwent robotic-assisted, video-enhanced coronary artery bypass grafting. All IMA's were harvested using the voice-activated robotic assistant (AESOP 3000, Computer Motion Inc, Santa Barbara, CA) and the Harmonic scalpel (Ethicon Endo-Surgery, Cincinnati, OH). Left IMA's were successfully harvested in all patients. Harvested IMA's were anastomosed to LAD's under direct vision through limited left anterior thoracotomy. The IMA harvest time was 57.8 +/- 23.2 min, intraoperative graft flow was 34.3 +/- 20.5 ml/min, postoperative hospital stay was 3.9 +/- 1.5 days. The early postoperative angiogram showed that all grafts were patent. There was no mortality, no significant morbidity. The robotic assisted, video enhanced CABG provides safe and complete LIMA dissection with minimal manipulation and assures sufficient LITA length for tension free anastomosis.

Adult↗
PubMed2000

Video-assisted thoracoscopy system guidance in linear radiofrequency ablation.

The transcatheter creation of linear endocardial lesions in the atria has been attempted to restore sinus rhythm in patients with atrial fibrillation (AF). However, due to fluoroscopic limitations, there are a number of technical difficulties involved with using this procedure, which include determining the ablation site, orienting the catheter tip, and confirming tip-tissue contact. The present study was performed to assess the feasibility of employing a transthoracic approach to linear radiofrequency ablation using a video-assisted thoracoscopy system (VATS) to anatomically guide the experimental setting in beating swine hearts. AF was induced pharmacologically by aconitine solution. Epicardial radiofrequency linear ablation of the right atrium was conducted under VATS monitoring using an ablation catheter that was inserted and manipulated through trocar ports. The ablation energy setting was 80 degrees C with 30s duration per ablation. The thoracoscopic visual field for transthoracic ablation was adequate, and the ablation catheter was positioned and anchored safely on the atrial epicardium. The restoration of sinus rhythm was confirmed in the limb lead and atrial electrograms, and transmural heat degeneration was confirmed by postmortem histological examination in all specimens. Our results suggest the potential usefulness of VATS for providing adequate anatomical guidance in epicardial linear radiofrequency ablation.

Animals↗
PubMed2000

Complications associated with clamping the aorta between the left common carotid artery and left subclavian artery.

BACKGROUND: Hypothermic circulatory arrest using a left thoracotomy has recently been recommended for repair of distal arch lesions to prevent the atheroembolism that often results from clamp injury. The recommendation holds even for cases in which aortic cross-clamping between the left common carotid artery and left subclavian artery is possible. METHODS: Over the last 16 years, 69 patients underwent repair of the distal arch or descending thoracic aorta using distal perfusion with the proximal aortic clamp placed between the left common carotid and left subclavian artery. The average age of the patients was 61+/-12 years; 18 of them (26%) were older than 70 years. Forty-four patients (64%) had atherosclerotic true aneurysms. RESULTS: The surgical procedures used included patch closure of saccular aneurysms in 20 patients (29%) and graft replacement in 47 (71%). The left subclavian artery was reattached in 7 patients (10%). Although there were 3 hospital deaths (4%), no cerebral complications occurred aside from temporary neurologic dysfunction in 4 patients (6%). CONCLUSIONS: An acceptably low incidence of cerebral complications is associated with cross-clamping the aorta between the left common carotid artery and left subclavian artery.

Adult↗
PubMed2000

Acute ischemic hepatic failure resulting from intraaortic balloon pump malposition.

We describe a rare intraaortic balloon pump (IABP) vascular complication as a result of malpositioning of the IABP. A 61-year-old man with unstable angina underwent emergency coronary artery bypass grafting soon after the insertion of an IABP. Postoperative hemodynamics were stable, but acute hepatic dysfunction occurred on the second postoperative day. Doppler echography revealed the absence of hepatic arterial flow. The IABP was removed, and arterial flow was immediately restored. Thereafter, the hepatic function recovered rapidly. This is a rare case that demonstrates how IABP can cause mechanical abdominal arterial branch obstruction. Evaluations using Doppler echography are useful in detecting such IABP complications.

Coronary Artery Bypass↗
PubMed2000

Development of a completely closed circuit using an air filter in a drainage circuit for minimally invasive cardiac surgery.

The completely closed circuit system is the future direction of cardiopulmonary bypass because of its compactness and superior biocompatibility. The most serious obstacle for clinical application is the sucking of air bubbles into the drainage circuit. The purpose of this study was to remove the air bubbles from the drainage circuit. Infusing 50 ml/min of air bubbles into the drainage circuit of the usual closed circuit, and infusing 50, 100, and 150 ml/min of air into the drainage circuit of a newly developed closed circuit (drainage circuit using an air filter), the number and size of air bubbles were observed at the outlet of the arterial filter. In the usual closed circuit, many air bubbles of over 40 microm were detected within 5 s at a blood flow of 4 L/min because the centrifugal pump decreased the size of the bubbles, which then passed through the oxygenator and arterial filter. Air bubbles of over 40 micro were not detected in the newly developed closed circuit within 5 min at a blood flow of 4 L/min. The removal of air mixed into the completely closed circuit was possible with a drainage circuit using an air filter that was developed. The clinical use of the completely closed circuit for minimally invasive cardiac surgery (MICS) became possible based on this development.

Air↗
PubMed2000

Vacuum assisted cardiopulmonary bypass in minimally invasive cardiac surgery: its feasibility and effects on hemolysis.

The present study describes a cardiopulmonary bypass (CPB) technique that incorporates vacuum assisted venous drainage and arterial return using a centrifugal pump in minimally invasive cardiac surgery (MICS). The technique was performed on 40 patients scheduled to undergo MICS. The proposed CPB technique enables a good operative field to be obtained even through a limited incision through the use of peripheral cannulation using small cannulae. Vacuum pressure was applied to the venous reservoir (-43 +/- 14 mm Hg) to maintain adequate CPB flow (>2.4 L x min-1 x M-2). The effects of CPB on hemolysis were subsequently compared between patients who underwent the proposed procedure (MICS group; n = 6) and a control group who underwent coronary arterial bypass grafting (CABG group; n = 6) with conventional CPB. Plasma free hemoglobin (FHb) increased and plasma haptoglobin (Hp) decreased during CPB in both groups, with no significant difference between the groups. By the next day, FHb had returned to pre-CPB levels whereas Hp remained lower in both groups. Again, these values did not differ significantly between groups. Thus, we conclude that the proposed CPB technique is useful in MICS with acceptable effects on hemolysis.

Analysis of Variance↗
PubMed2000

Closed circuit cardiopulmonary bypass with centrifugal pump for open-heart surgery: new trial for air removal.

The purpose of this study is to examine the efficiency of venous air removal with a new cardiopulmonary bypass (CPB) circuit design for conventional open-heart surgeries. A main concern with a closed circuit for open-heart surgeries is air entrainment into the venous line. A venous filter was placed proximal to the centrifugal pump. The circuit proximal to the centrifugal pump was divided into two lines; one line was attached to the venous reservoir outlet. By clamping the line to the reservoir, this circuit becomes closed. Negative pressure was applied to the purge line connected to the venous reservoir for venous air removal. Micro bubbles were measured at two locations, both distal to the venous and arterial filters. When the injection rate reached 100 ml/min, with the air-injection over 30 s, micro bubbles greater than 40 micro were observed at the outlet of venous filter. However, there was no micro bubble greater than 40 micro detected at the outlet of arterial filter. Although micro bubbles greater than 40 micro were not detected at the outlet of the arterial filter up to the injection rate of 300 ml/min, when the injection rate reached 400 ml/min, micro bubbles greater than 50 microm were detected distal to the arterial filter. From this examination, we determined that air entrained in the venous line up to approximately 300 ml/min is automatically removed by this method with the pressure-balanced condition. This pressure balance means that resistance of venous return, gravity siphon, negative pressure by centrifugal pump, and negative pressure applied to the air-purge line of the filter are balanced; that is, the venous return is sufficient, and the venous reservoir volume is kept stable. From this study we determined that this circuit design efficiently removes the entrained air in the venous line.

Air↗
PubMed1999

The surgical treatment of fixed subaortic stenosis: a clinical experience in Japan.

We report herein the results of a retrospective study conducted on ten consecutive Japanese patients who underwent successful surgical relief of fixed subaortic stenosis between 1972 and 1994 at ages ranging from 8 months to 21 years, and followed for 3.6 years and 26 years. Associated cardiovascular defects were present in six patients, two had a history of infective endocarditis, a discrete fibrous ring was found in nine patients, and a redundant abnormal sheet was found in one. A stenotic structure was removed in nine patients and incised in one, while myotomy was additionally performed in one. There were no early complications or deaths. Cardiac catheterization revealed a significant decrease in the peak systolic pressure gradient from 84+/-22 mm Hg preoperatively to 32+/-22 mm Hg postoperatively (P = 0.0017). Reoperation of an aortic valve replacement with or without valvular annulus enlargement was required in four patients because of a small annulus with aortic insufficiency or infective endocarditis. Infective endocarditis was a major cause of late mortality (n = 1) and morbidity (n = 1), but the remaining eight patients have been asymptomatic. Thus, although this lesion is relatively rare in Japan, the typical discrete type may be more common than previously believed. While a relief operation is associated with low early mortality, the palliative aspect regarding pathology of the aortic valve should not be underestimated, including poor growth of the valve annulus, deterioration of aortic insufficiency, and infective endocarditis. The most appropriate operative procedure for reoperation remains to be evolved.

Adolescent↗
PubMed1999

Prognosis of Marfan and non-Marfan patients with cystic medial necrosis of the aorta.

The characteristics and prognosis of patients with cystic medial necrosis of the aorta were reviewed. Subjects were 46 patients who underwent aortic and/or aortic valve surgery between August 1965 and October 1994. All had histologically documented cystic medial necrosis including 22 Marfan patients. The patients with Marfan syndrome were substantially younger (median age, 32 vs 50 years; p < 0.05), and experienced annulo-aortic ectasia more frequently {81% (17/22) vs 46% (11/24); p < 0.05} than those without the syndrome. Sixty-eight percent (15/22) of the Marfan patients and 63% (15/24) of the non-Marfan patients experienced complications with aortic dissection, although not to a significant degree. The hospital mortality rate was 14% (3/22) in the Marfan group and 21% (5/24) in the non-Marfan group, which was also not significant. Of the 38 survivors, developments in the health of 37 were completely followed-up until October 1997. The cardiovascular event-free rate for Marfan patients at 10 years (28%) was lower than that for non-Marfan patients (68%, p = 0.057), whereas the actuarial survival rates at 10 years were nearly equal (72% for the Marfan patients and 74% for the non-Marfan patients). Reoperation was the first cardiovascular event in 77% (10/13) of the Marfan patients and in 14% (1/7) of the non-Marfan patients (p < 0.05). Cardiovascular event was the main cause of late death both for Marfan patients (80%; 4/5) and for non-Marfan patients (86%; 6/7). In conclusion, independent of the presence of Marfan syndrome, careful follow-up is necessary for patients with cystic medial necrosis of the aorta to eliminate serious late complications.

Adolescent↗
PubMed1999

Effect of storage temperature on cell viability in cryopreserved canine aortic, pulmonic, mitral, and tricuspid valve homografts.

We determined how long cryopreserved aortic, pulmonic, mitral, and tricuspid valve homografts could be stored in a deep freezer (-80 degrees C) without compromising fibroblast viability. Valves harvested from 20 anesthetized mongrel dogs were grouped into nonfrozen control, frozen and stored in liquid nitrogen (-196 degrees C), and frozen and stored in a deep freezer (-80 degrees C). Frozen groups were divided into subgroups and stored for 2, 4, 8, or 12 weeks. A leaflet of each valve was divided into three fragments, and fibroblast viability was analyzed by flow cytometry. Cell viability was defined as staining by fluorescent diacetate but not by propidium iodide. The viability of untreated control valves from all four sites was about 70%, decreasing to about 50% when treated with low doses of antibiotics. The viability of frozen valves stored in liquid nitrogen was about 45% without a significant difference among storage periods. The viability of valves frozen and stored in a deep freezer was significantly lower than for the liquid nitrogen group at 2 weeks for the mitral valve and at 4 weeks for other valves. These results suggest that homografts can be stored in a deep freezer for up to 2 weeks without deterioration.

Animals↗