Efficiency of an air filter at the drainage site in a closed circuit with a centrifugal blood pump: an in vitro study

In a closed circuit with a centrifugal blood pump, one of the serious obstacles to clinical application is sucking of air bubbles into the drainage circuit. The goal of this study was to investigate the efficiency of an air filter at the drainage site. We used whole bovine blood and the experimental circuit consisted of a drainage circuit, two air filters, a centrifugal blood pump, a membrane oxygenator, a return circuit, and a reservoir. Air was injected into the drainage circuit with a roller pump, and the number and size of air bubbles were measured. The air filter at the drainage site could remove the air bubbles (>40 microm) by itself, but adding a vacuum removed more bubbles (>40 microm) than without vacuum. Our results suggest that an air filter at the drainage site could effectively remove air bubbles, and that adding the filter in a closed circuit with a centrifugal blood pump would be safer.

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.

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.

A New Endo Aortic Occlusion Balloon for Limited Access Cardiac Surgery: Development and Clinical Evaluation

In recent years, minimally invasive cardiac surgery (MICS), or limited access cardiac surgery, has been presented as a promising operative procedure. We developed a new balloon device that is inserted directly into the ascending aorta to stop the heart during limited access cardiac surgery. The balloon has a three lumen structure: balloon lumen port, cardioplegia/vent lumen port, and aortic root lumen port. This direct EAC balloon catheter, designed to be inserted directly into the ascending aorta, is different from the Heartport system. The Heartport EAC balloon catheter is inserted into the aorta via an artery in the lower limb, making lower limb arterial disease a key concern. Our Direct Endo Aortic Clamp (EAC) balloon overcomes this problem. The device was clinically used in seven cardiac cases. All patients were discharged within 5 postoperative days, confirming the utility of the device.

Surgical treatment for a ruptured thoracic aortic aneurysm

OBJECTIVE

The treatment for a ruptured thoracic aortic aneurysm remains controversial. This study was undertaken to assess the outcome from surgery.

METHODS

Between 1993 and 1998, we have performed 19 operations for a ruptured thoracic aortic aneurysm. Patients with an impending rupture or a chronic false aneurysm were excluded. There were 11 men and 8 women, with a mean age of 70.5 +/- 6.7 years. The aneurysm was caused by dissection in 8 patients. Of these, 7 were acute (Stanford type A, 6; type B, 1), and the other one was chronic (type B). Aortic rupture occurred into the pericardial cavity (n = 7), into the left lung (n = 6), the mediastinum (n = 3), the pleural cavity (n = 2), or into the esophagus (n = 1). Severely unstable hemodynamics were noted in 12 patients with a rupture into the pericardium, mediastinum, or pleural cavity (Group A). Inotropic support was required in each of these patients. Metabolic acidosis developed all but 1 patient. The 7 patients with a rupture into the lung or esophagus coughed or vomited blood (Group B). The operative approach was anterior (n = 17) or lateral (n = 2). Grafts were placed in the ascending aorta (n = 4), ascending and transverse arch aorta (n = 7), transverse arch aorta (n = 3), or in the descending thoracic aorta (n = 5). Selective cerebral perfusion was used in 13 patients.

RESULTS

There were 5 hospital deaths (26.3%). The postoperative complications included central nervous system dysfunction (n = 3), low cardiac output syndrome or cardiac arrhythmias (n = 3), respiratory failure (n = 4), acute renal failure (n = 1), and local or systemic infections (n = 4). The perioperative event-free rate was 36.8% overall, 25% in Group A, and 57.1% in Group B.

CONCLUSIONS

Patients with unstable hemodynamics require prompt operative intervention. Rupture into the esophagus is associated with a high mortality rate. Rupture in a thoracic aortic aneurysm can be successfully treated with emergency surgery.

Efficacy of autologous platelet-rich plasma in thoracic aortic aneurysm surgery

OBJECTIVE

Allogenic blood transfusion can transmit viral infection or cause immunological side effects. Recently, improved operative techniques have required less frequent transfusions in thoracic aortic aneurysm surgery. This study examined the efficacy of using autologous platelet-rich plasma in thoracic aortic aneurysm surgery.

METHOD

Eight patients underwent nine operations using an autologous platelet-rich plasma program. The control group consisted of 15 historic patients matched for operative procedure and age. All operations were performed by the same surgeon. The platelet-rich plasma program required the collection of platelet-rich plasma prior to the infusion of heparin; platelet-rich plasma transfusions were administered following neutralization by heparin.

RESULTS

The volume of platelet-rich plasma averaged 252 +/- 14.3 ml; total platelets in the platelet-rich plasma were 2.27 +/- 0.20 x 10(11) cells. The median number of homologous red blood cells transfused during the operative day was 0 units (range 0 to 12) in the platelet-rich plasma group and 3 units (range 0 to 25) in the controls. The median number of homologous fresh frozen plasma was 0 units (range 0 to 20) in the platelet-rich plasma group, and 5 units (range 0 to 30) in the controls. The platelet-rich plasma group received significantly fewer transfusions.

CONCLUSION

Autologous platelet-rich plasma transfusion was an effective way to reduce homologous blood transfusions in thoracic aortic aneurysm surgery.

[Effect of Down's syndrome on perioperative and long-term prognosis after ventricular septal defect repair]

In this study, we investigated perioperative and long-term prognosis and the risk of major complications after repair of ventricular septal defect in 48 patients with Down's syndrome who underwent ventricular septal defect repair between May 1980 to August 1999 were compared with those in 48 patients with normal chromosomes matched for age and time period. Pp/Ps were significantly lower after the operation in both groups; however perioperative and postoperative Pp/Ps of Down's syndrome group were significantly higher than that those of control group. The duration of intubation was significantly longer in the Down's syndrome group and the case-control study revealed that the risk of long intubation (> or = 7 days) was significantly higher in the Down's syndrome group, but the incidence of PH crisis did not differ between the 2 groups. The main reasons of prolonged intubation period were respiratory complications such as pneumonia or atelectasis. In Down's syndrome group, a 5 months old boy died of heart failure on the 5th postoperative day. All other patients were survived through a mean follow-up period of 122.4 months (the follow-up rate was 95.8%). In conclusion, the perioperative and long-term prognosis after ventricular septal defect repair in patients with Down's syndrome were similar to those in patients with normal chromosome.

Placement of interatrial patch suture lines in atrioventricular canal defect repair

BACKGROUND

The placement of the suture line for interatrial patches in complete and incomplete atrioventricular canal defect repairs varies from surgeon to surgeon despite established anatomic knowledge of the atrioventricular conduction system. This study describes our technique for it and reviews early and long-term outcomes.

METHODS

Between 1980 and 1999, 64 infants and children underwent repair of either complete (n=39) or incomplete (n=25) atrioventricular canal defects. Thirty-four of the children (53.1%) had Down's syndrome. The suture line for the interatrial patch originated on either the artificial or native ventricular septal crest and continued leftward above the annulus of the left inferior leaflet of the atrioventricular valve at the posteroinferior corner. All stitches were placed in a horizontal mattress or U-shaped fashion.

RESULTS

The operative survival rate was 94% (4 early deaths) and the overall survival rate was 85% (6 late deaths). Atrioventricular heart blocks occurred in none of the patients. Although left-sided atrioventricular function significantly improved with repair, two patients (3.1%) required reoperation for valve replacement because of residual or recurrent insufficiency.

CONCLUSIONS

This suture technique for interatrial patches is straightforward and results in a low incidence of heart block and a low re-operation rate for left atrioventricular valve insufficiency.

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.

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.

Mitral valve replacement in patients younger than 6 years of age

We present our experience in mitral valve replacement (including left-sided tricuspid valve in corrected transposition) in patients younger than 6 years of age. The long term results were examined with special focus on re-replacement of the valve. Between 1974 and 1995, we performed mitral valve replacement in 14 patients younger than 6 years of age, with no operative mortality. There were 3 late deaths, caused by endocarditis, valve thrombosis, and congestive heart failure, respectively. The five-year-survival rate after primary replacement was 85%, and the ten-year-survival rate was 75%, using Kaplan-Meier analysis. Ten patients (11 occasions) required repeated mitral valve replacements at 2 months to 17 years after the original replacement. The indication for the second or third mitral valve replacement was paravalvular leakage (2 patients), valve thrombosis (1 patient), degeneration in the porcine prosthesis (3 patients), and patient outgrowth of the original small prosthesis (5 patients). Again there was no operative mortality. One patient who suffered from multiple occasions of valve thrombosis died at two years after the second replacement. All patients who had outgrown the prosthetic valve received larger prosthesis at the second replacement than at the primary replacement. The actuarial percentage of freedom from valve-related events at 3 years, 5 years, and at 10 years, was 50%, 37%, and 8%, respectively.

CONCLUSIONS

Mitral valve replacement in patients younger than 6 years of age can be performed relatively safely, but meticulous follow-up and appropriate decision making for re-replacement is mandatory for the long-term survival of these patients.

[Near-infrared spectroscopy during hypothermic selective cerebral perfusion--a clinical study of its value]

The purpose of this study is to assess the value of near-infrared spectroscopic oxymetry (NIRO) in monitoring cerebral oxygenation and metabolism during selective cerebral perfusion (SCP) for surgery of the aortic arch. The measurement protocol during SCP comprised oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), and total hemoglobin levels in the brain. From March 1994 through March 1997, 14 patients underwent surgical treatment of the aortic arch anomalies with intraoperative monitoring with NIRO. The temporary circulatory arrest was accomplished at a rectal temperature of 22 degrees C and the hypothermic SCP was employed for the cerebral protection. SCP was initiated at a flow rate of 10 ml/kg/min so as to maintain HbO2 at the same level as immediately before the circulatory arrest (baseline). The longitudinal changes of HbO2 level during the process revealed four different patterns and were grouped accordingly. Three of the patients maintained HbO2 level above the baseline during SCP (Group A). HbO2 level reached to the baseline at initial flow rate but decreased gradually thereafter in 4 patients (Group B). Gradual increment of the perfusion flow rate failed to elevate HbO2 level to the baseline in the 5 patients (Group C1). In this group, HbO2 level started to elevate about 60 minutes after the initiation of SCP. HbO2 level of the remaining 2 patients was absolutely resistant to the increment of SCP flow rate and kept low values throughout SCP (Group C2). All the patients recovered uneventfully without any neurological abnormality. Our analyses for the longitudinal behavior of the HbO2 level confirmed the previously reported evidences that the values were affected not only by perfusion flow rate but also by hemodilution, blood transfusion, and perfusion pressure. Furthermore, our present study disclosed another evidence that HbO2 level was strongly affected by subclavian steal phenomenon. Although there were no differences in the clinical outcome among the groups, referring to the theories that HbO2 level is better not to be departed from baseline level, it could be concluded that HbO2 level monitoring in the setting of the determined hematocrit and hypothermia was effective for securing the adequate demand and supply balance of the cerebral oxygenation. Our conclusion may extend further that NIRO is a useful means in determining the optimal perfusion flow rate of SCP during surgery of the aortic arch.

Video-assisted cardioscopic staple closure for atrial septal defect

Our goal was to determine the feasibility of video-assisted cardioscopic closure of atrial septal defect (ASD) without cardiopulmonary bypass using a staple catheter device and guiding catheter in an experimental setting. An artificial linear atrial septal defect (AASD) was created in 7 swine under video-assisted cardioscopic view, and staple closure was attempted at the AASD with a stapler inserted through a trocar guiding catheter via the right atrium under median sternotomy. The staple device was successfully and safely anchored in 4 animals. The whole process of stapling could be monitored by cardioscope and by post mortem macroscopic examination. In conclusion, although the size and flexibility of the stapler and the guiding catheter must be improved, our results demonstrate that there is a strong potential for video-assisted staple closure of ASD using this novel technique, which could contribute to the reduction of the number of open heart operations and thereby iatrogenic morbidity.

[A case report of postcoarctation mycotic aneurysm after surgical treatment for cerebral arterial aneurysms]

Postcoarctation mycotic aneurysm of the aorta is very rare. We present a case of a 55-year-old man with postcoarctation mycotic aneurysm of the aorta infected with methicillin resistant staphylococcus aureus (MRSA) after surgical treatment for cerebral arterial aneurysms. The operation was performed after negative conversion of MRSA in blood culture using antibiotics. The mycotic false aneurysm was completely resected following institution of an extra-anatomical bypass from the ascending aorta to abdominal aorta above celiac artery.

[Early and late results of cardiac and thoracic aortic surgery in patients older than 75 years from a quality of life point of view]

To determine the early and late results of cardiovascular surgery in patients older than 75 years old, we performed a retrospective study of 28 consecutive elderly patients between January, 1987 and July, 1996. Fourteen patients had cardiac surgery, and 14 had thoracic aortic surgery. Among all of them, nine patients had an emergency operation. The follow-up time ranged 7 to 76 months (mean 20.7 +/- 25.0). The total follow-up time was 561 patients months. The hospital mortality rate was 32.1% (9/28) over all and 15.8% (3/19) for the elective procedures. The early result during the latter five years decreases more than during the early five years (55% vs. 18%, respectively). Three patients died during the follow-up period. One patient dropped out of the follow-up. All 15 survivors were satisfied with their quality of life. Among the survivors of cardiac surgery, the mean New York Heart Association functional classification score decreased significantly (preoperative 3.0 +/- 0.89, follow-up 1.5 +/- 0.55). Though the early mortality is unsatisfactory, it is improving. This follow-up study demonstrates the benefits of cardiovascular surgery in elderly patients in terms of social integration and quality of life.

Video assisted thoracoscopic and cardioscopic radiofrequency Maze ablation

The authors examined the feasibility of transthoracic radio frequency Maze ablation of atrial fibrillation using video assisted thoracoscopy and cardioscopy in the experimental setting of a beating porcine heart. In six pigs under general anesthesia, the left atrium was viewed using a video assisted thoracoscopy system (VATS), and radiofrequency linear ablation of the left atrial wall was carried out using a radiofrequency ablation catheter (HAT200S:OSYPKA) inserted through a trocar port. The right atrium was also ablated in the same manner under VATS. In six other pigs, intravenous radiofrequency ablation by cardioscopic catheter device was carried out. Atrial fibrillation was provoked by acetylcholine injection plus rapid atrial pacing. The thoracoscopic visual field created for radiofrequency catheter ablation from a transthoracic approach and the cardioscopic visual field from an intravenous approach were sufficient, and safe positioning of the ablation catheter device on the atrial epicardium and endocardium, which enabled linear ablation of the atrium, was obtained. The Optimal setting for ablation was 70-80 degrees C/ 30 sec duration per each ablation. This process was monitored and documented by a video system through the thoracoscope and cardioscope, and results were confirmed by postmortem macrohistologic examination. In conclusion, the authors' results suggest the potential usefulness of the combination of transthoracic radiofrequency catheter ablation with video assisted thoracoscopic and cardioscopic linear ablation of atrial fibrillation, and the possibility that use of this system might eliminate the need for open heart Maze surgery.

Experimental study of combination of extraaortic balloon counterpulsation and ventricular assist cup to acute heart failure in dogs

The goal of this study is to evaluate the applicability and effectiveness of combination support of the extraaortic balloon (EAB) and the ventricular assist cup (VAC) to the acute heart failure model. Under general anesthesia, 10 adult dogs were used. Through the median sternotomy, EAB was placed around the ascending aorta and VAC in the pericardial cavity. After heart failure was induced by administration of propranolol, the on-off tests of devices were done as follows. Only EAB was used, and only VAC was used and both devices were used. Regional blood flows (RBFs) of both ventricles, liver kidneys, and brain were measured by colored microsphere technique. Hemodynamic parameters were also measured. In heart failure model, cardiac output (CO) decreased to 66% of control value. In the group assisted by EAB, aortic peak-diastolic pressure and RBFs of both ventricle and brain increased significantly. In the group assisted by VAC, CO and RBFs of all but the left ventricle significantly increased. In the group assisted by EAB and VAC, aortic peak-diastolic pressure, CO, and all five RBFs significantly increased. These results suggest the combination of EAB and VAC is applicable and effective and would be a promising implantable device for the chronic heart failure.

Detrimental effects of exogenous glutamate on spinal cord neurons during brief ischemia in vivo

BACKGROUND

Paraplegia remains a serious complication of thoracoabdominal aortic operations. However, despite growing in vitro evidence, it has been difficult to demonstrate glutamate neurotoxicity in vivo because of the reuptake activity that occurs. We hypothesized that glutamate can be toxic to the spinal cord under metabolic stress.

METHODS

Infrarenal aortic isolation was performed in New Zealand white rabbits. Group A animals (n = 7) then received a segmental infusion of glutamate (50 mmol/L) for 5 minutes. Group B animals (n = 7) received saline as a negative control. Group C animals (n = 6) were pretreated with a segmental infusion of 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)-quinoxaline (4 mg/kg), a competitive alpha-amino-3-hydroxy-5-methylisoazole-4-propionic acid/kainate antagonist, followed by the segmental infusion of glutamate (30 mmol/L) for 4 minutes. Group D animals (n = 6) received the vehicle agents only, followed by the same glutamate infusion (30 mmol/L) as in group C as a control for group C. Neurologic status was assessed at 12, 24, and 48 hours after operation and scored using the Tarlov system.

RESULTS

Group A animals exhibited paraplegia or paraparesis with marked neuronal necrosis. Group B animals recovered fully. Group C animals had better neurologic function than group D animals (p = 0.0039).

CONCLUSIONS

Exogenous glutamate can have detrimental effects on spinal cord neurons during a brief period of ischemia. This model may be useful for the purpose of assaying a glutamate receptor antagonist in vivo.

[Surgical repair of a dissecting aortic aneurysm with entry at proximal descending aorta through left thoracotomy--a case report]

A 45-year-old man underwent a distal arch and descending aortic replacement through a left thoracotomy. His chronic type A dissecting aortic aneurysm had the entry at the proximal descending aorta. After 9 years of his first dissection, he suffered from a second dissection. In computerized tomogram (CT), the ascending and descending aorta enlarged to 6.0 cm and 7.0 cm in diameter, respectively and descending aorta showed a three channeled dissection. The open proximal anastomosis technique was used under the deep hypothermic circulatory arrest (HCA) followed by selective cerebral perfusion (SCP). Surgical repair included the obliteration of the proximal false lumen at the level between the left carotid and subclavian artery. A thrombosed retrograde dissection in the ascending aorta was revealed in postoperative evaluation, and decreased in size at follow up CT.

[A successful surgical case of a dissecting aortic aneurysm with right-sided aortic arch and right-sided descending aorta]

The patient was a 70-year-old female whose aortogram and chest computer tomogram revealed DeBakey type IIIb dissecting aortic aneurysm in association with right-sided aortic arch, right-sided descending aorta and aberrant left subclavian artery arising from the Kommerell's diverticulum. Because she had cachexy with hoarseness and difficulty in swallowing caused by an aneurysm she received hypotensive therapy until recovery of her general condition before elective operation. The aneurysm was 7 cm in diameter and was replaced with vascular graft. Reconstruction of the aberrant left subclavian artery and closure of the false lumen via right thoracotomy were also performed under partial bypass installed between the right common femoral vein and artery using modified PCPS. Postoperative computer tomogram and aortogram showed properly replaced vascular graft and closure of false lumen. Dissecting aortic aneurysm complicated with a right-sided arch is quite rare. Including our case, 12 cases have been reported in the world and 9 cases were in Japan. This is one of the most successful surgical case for DeBakey type IIIb dissecting aortic aneurysm in association with right-sided aortic arch, right-sided descending aorta and aberrant left subclavian artery arising from the Kommerell's diverticulum.

Experimental study of extraaortic balloon counterpulsation as a bridge to other mechanical assists

A special extraaortic balloon was developed that can be placed around the ascending aorta. This balloon can easily support the heart temporarily in a median sternotomy field, especially in cases in which it is difficult to use intraaortic balloon pumping because of peripheral arterial disease. The goal of this study was to judge the applicability of this extraaortic balloon counterpulsation. An extraaortic balloon was placed around the ascending aorta of eight adult canines. Two heart failure models were used in this study: group A-moderate heart failure; group B-severe heart failure. In group A, the aortic systolic pressure was significantly reduced (9.3%, p < 0.01), but in group B, there was no significant change. In group A, there was a significant increase in cardiac output (12.0%, p < 0.01), but in group B, there was no significant change. The endocardial viability ratio in both groups significantly increased (group A: 11.3%, p < 0.01; group B: 11.9%, p < 0.05). An extraaortic balloon around the ascending aorta is easily applicable through a median sternotomy, and can be used as a bridge to more powerful mechanical assists when intraaortic balloon pumping cannot be used.

[The surgical treatment of coarctation of the aorta and interruption of the aortic arch in the first three months of life--effectiveness of temporary bypass between the pulmonary artery and the descending aorta]

From February 1987 to January 1994, we operated on 24 patients with coarctation of the aorta (CoA) and 9 patients with interruption of the aortic arch (IAA). A policy of staged repair was followed, consisting of reconstruction of the aortic arch with pulmonary artery banding and ligation of the ductus arteriosus in the first stage and intracardiac repair with pulmonary artery band removal in the second stage. In recent cases an extended aortic arch anastomosis was performed using a heparin-coated "shunt tube" between the pulmonary artery and the descending aorta to maintain blood flow to the lower half of the body during aortic cross-clamping. The use of the shunt increased intraoperative urine output (p < 0.05). This technique may allow patients whose condition is poor to undergo aortoplasty more safely. One patient died. This patient had CoA and total anomalous pulmonary venous return, who underwent a one-stage repair, in violation of our policy (early mortality 3.0%). There were two interim deaths before the second stage repair. At present, 18 patients have undergone staged intracardiac repair, including VSD closure (14 cases), Jatene's procedure (1), Ratelli's procedure (1), Damus-Kaye-Stansel (DKS) procedure (1), total cavo-pulmonary connection (TCPC) + DKS procedure+annuloplasty of a common atrioventricular valve (1). There were two early deaths and one late death following intracardiac repair, all in patients with IAA plus VSD.

[Preliminary clinical results of surgery for type A acute aortic dissections using gelatin-resorcin-formaldehyde glue]

We used gelatin-resorcin-form-aldehyde (GRF) glue to fuse the false lumen of type A acute aortic dissection in four patients. All were operated on within 3-24 hours after onset, and gluing of the two cylinders of the dissecting aorta could be done safely in a short time. Initial intimal tears were located in the transverse aorta in three patients and in the proximal descending aorta in one. Simple transection and end-to-end anastomosis of the ascending aorta was done for the first two cases. But in the last two patients, we resected the intimal tear in the transverse aorta and applied GRF glue to the stump of the aortic arch and to that of the aortic root, followed by graft replacement of the ascending aorta. There were no hospital deaths. But we had to reoperate on one patient five months after the first operation due to potentially residual dissection in the aortic root. GRF glue is a very useful adhesive for acute aortic dissection operations, but further refinement of the operative technique using it is necessary.

Feasibility study of vascular-endoscopic valvuloplasty. Using a laser and flexible endoscope

Percutaneous balloon valvuloplasty is generally accepted, but post procedural complications limit its efficacy and reduce long-term success. To eliminate these risks, the authors explored the feasibility of cardioscopy guided percutaneous laser valvuloplasty in an experimental setting. The combined working model consisted of a separate balloon tipped thin fiber optic endoscope, laser balloon catheter, and a Nd-YAG laser transmitter. A porcine pulmonary valve was used as our in vivo target of laser ablation in a beating heart. Under general anesthesia, the endoscopic catheter is delivered into the pulmonary valve area through either the internal jugular or femoral vein under fluoroscopy. Positioning the pulmonary apparatus coaxial to the endoscopic visual field by manipulation of the catheter allowed for targeting and ablation of the commissure of the pulmonary valve under endoscopic view through the balloon filled with saline solution. The ablation energy was 15-30 W, 0.5-1.0 sec, and 2,000-3,000 J total. The animal was then killed and histopathologic study of the ablated area was done. The commissure of the pulmonary valve was smoothly ablated in 4 cases, and the entire ablation procedure was successfully witnessed through endoscopy. The authors encountered some difficulty in laser targeting, limitations to the endoscopic field of vision, and difficulty in holding the position of the apparatus in the beating heart. These are the barriers to overcome for future clinical application of this procedure. However, these results indicate the clear possibility of future use of cardioscopy guided percutaneous laser valvuloplasty in a clinical setting.

Development and clinical application of a next generation implantable echocardiography probe for monitoring cardiac function under assisted circulation after open heart surgery

Post-operative cardiac function generally is monitored by electrocardiography, invasive measurement of blood pressure, and determination of hemodynamic variables, such as pulmonary pressures and cardiac output with a Swan-Ganz catheter. In recent years, transesophageal echocardiography has been introduced into clinical use, but it is not a popular method of monitoring for various reasons, including the difficulty of application to unconscious post-operative patients. Since 1991, we have been developing a small implantable echocardiography probe. This probe was tested in 15 patients who underwent open heart surgery for severe left ventricular hypofunction, and its clinical utility was demonstrated. No deaths occurred in this series. The implantable echocardiography probe allowed post-operative cardiac function to be monitored in real-time. The ejection fraction, the cardiac output, the status of valves after valvuloplasty, the presence of cardiac tamponade, and other variables could be assessed. The echocardiography probe can be positioned at any site where specific information is desired during surgery. It can be inserted as easily as a pericardial drain tube and is removed in the same manner when no longer necessary. This probe has the potential to be useful for monitoring patients on assisted circulation after cardiac surgery.

Surgical reconstruction of an ascending aortic dissection in Takayasu's arteritis

A 45-year-old Japanese woman with Stanford type A dissecting aortic aneurysm underwent a reconstructive operation on the ascending aorta. Histopathological diagnosis was Takayasu's arteritis in the chronic and inactive phase. It is very rare that a dissecting aortic aneurysm results from Takayasu's arteritis. Long-standing hypertension and fragility of the aortic media due to disruption of elastic fibers were suspected to cause dissection in the entire aorta in this case.