Development of a highly efficient implanted thermal ablation device: in vivo experiment in rat liver

OBJECTIVES

To evaluate an implanted thermal ablation device that can be heated with high efficiency using a resonant circuit as the implant.

METHODS

16 rats were used. The implants, adjusted at a resonance frequency of 4 MHz, were fixed on the surface of the liver of rats under laparotomy. In 14 of 16 rats, an alternating magnetic field (AMF) was applied for 6 min with an output of 300 W from outside the body using a ferrite core applicator. The implant temperature during AMF exposure was measured. The 14 rats were divided into 5 groups, depending on time from AMF application until they were sacrificed (1 h, 1 day, 3 days, 7 days and 1 month after application). Two rats not exposed to AMF were used as controls. Livers were removed and evaluated; the cross-sectional area and width of the ablated region were measured.

RESULTS

During AMF exposure, the implant temperature rose to 127.8±39.3 °C (mean±standard deviation). The cross-sectional area of the ablated region was largest after 1 day and tended to decrease with time. The widths of the ablated region were 4.87±0.22 mm, 4.15±0.36 mm, 3.67±0.58 mm and 3.24±0.16 mm in the 1 day, 3 day, 7 day and 1 month groups, respectively. No significant differences (p<0.05) were seen in either cross-sectional area or width of the ablated region.

CONCLUSION

Sufficient heat for ablation was obtained in vivo using a newly developed implanted thermal ablation device. This device may be a new option for thermal ablation therapy.

Midterm results after aortic valve-sparing operation

OBJECTIVES

We have conducted aortic valve-sparing operation for patients having aortic root dilatation and almost normal aortic valve leaflets since August 1998, and here report midterm results.

METHODS

Patients with dilated aortic annulus or Marfan's syndrome were treated with reimplantation, and the remaining patients with remodeling. Either 24 or 26 mm graft was selected based on aortic annular diameter and leaflet size. Aortic valve competence was assessed regularly with echocardiography.

RESULTS

Five patients (age: 29 +/- 13 yr), including 4 with Marfan's syndrome, had undergone reimplantation, and 3 (age: 46 +/- 18 yr) remodeling by December 2000. Mean follow-up was 18 (range: 10-32) months, and no postoperative death has occurred and no reintervention has been required thus far. All the patients in the remodeling group showed only a small pressure gradient through the aortic valve and decreased left ventricular diameter. Two in the reimplantation group showed a pressure gradient exceeding 20 mmHg. Two Marfan's syndrome patients in the reimplantation group showed slightly increased diastolic left ventricular diameter and 3 slightly increased systolic left ventricular diameter. Although aortic regurgitation had diminished in all patients by discharge, moderate aortic regurgitation recurred in 1 non-Marfan's syndrome patient in the reimplantation group because of degenerated aortic valve.

CONCLUSION

Although postoperative aortic valve function was not perfect in all patients undergoing reimplantation, midterm results after aortic valve-sparing operation were generally satisfactory. Proper selection of patients, procedures, and graft size was thought to be important to ensure a favorable surgical outcome.

Hemodynamic responses to intrapleural insufflation with hemipulmonary collapse

BACKGROUND

The hemodynamic effects of carbon dioxide (CO2) insufflation with hemipulmonary collapse were studied in consecutive thoracoscopic harvests of the left or right internal mammary artery (IMA), which were used for video-assisted coronary artery bypass grafting.

METHODS

Thirty-eight patients (30 male, eight female) with a mean age of 69.5 +/- 11.5 years were selected, and 33 left and five right IMA were harvested thoracoscopically. After hemipulmonary collapse was established by single-lung ventilation, low-flow (2-3 L/min) CO2 was delivered at a constant intrapleural pressure of 8-10 mmHg. Using electrocardiography, a radial arterial catheter, a Swan-Ganz catheter, and transesophageal echocardiography, we obtained values for seven hemodynamic variables. Baseline data were collected during bilateral lung ventilation. Each variable was then measured during hemipulmonary collapse and insufflation. The significance of any changes was established with Student's t-test after correcting for baseline differences.

RESULTS

Insufflation facilitated IMA harvest by expanding the pleural space between the anterior chest wall and heart. Mean insufflation times were 40.8 +/- 12.2 min on the left and 33.5 +/- 8.5 min on the right. Significant increases from the baseline values were observed in the mean central venous pressure (L:4.7-9.0 mmHg, R: 5.1-14.0 mmHg, p < 0.05), the pulmonary arterial pressure (L: 11.3-17.3 mmHg, R: 12.1-19.9 mmHg, p < 0.05), and the pulmonary capillary wedge pressure (L: 7.2-10.5 mmHg, R: 6.5-10.0 mmHg, p < 0.05). On the right, but not on the left, slight decreases were noted in the mean arterial pressure and cardiac index (71.3-62.6 mmHg, 2.01-1.76 L min-1 m-2, p < 0.05).

CONCLUSIONS

The hemodynamic effect resulting from one-lung collapse plus low-flow CO2 insufflation at 8-10 mmHg for 30-40 min is mild in both hemithoraces, although the impact is greater on the right.

Arterial blood gas management in retrograde cerebral perfusion: the importance of carbon dioxide

OBJECTIVES

Many interventional physiological assessments for retrograde cerebral perfusion (RCP) have been explored. However, the appropriate arterial gas management of carbon dioxide (CO2) remains controversial. The aim of this study is to determine whether alpha-stat or pH-stat could be used for effective brain protection under RCP in terms of cortical cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), and distribution of regional cerebral blood flow.

METHODS

Fifteen anesthetized dogs (25.1+/-1.1 kg) on cardiopulmonary bypass (CPB) were cooled to 18 degrees C under alpha-stat management and had RCP for 90 min under: (1), alpha-stat; (2), pH-stat; or (3), deep hypothermic (18 degrees C) antegrade CPB (antegrade). RCP flow was regulated for a sagittal sinus pressure of around 25 mmHg. CBF was monitored by a laser tissue flowmeter. Serial analyses of blood gas were made. The regional cerebral blood flow was measured with colored microspheres before discontinuation of RCP. CBF and CMRO2 were evaluated as the percentage of the baseline level (%CBF, %CMRO2).

RESULTS

The oxygen content of arterial inflow and oxygen extraction was not significantly different between the RCP groups. The %CBF and %CMRO2 were significantly higher for pH-stat RCP than for alpha-stat RCP. The regional cerebral blood flow, measured with colored microspheres, tended to be higher for pH-stat RCP than for alpha-stat RCP, at every site in the brain. Irrespective of CO2 management, regional differences were not significant among any site in the brain.

CONCLUSIONS

CO2 management is crucial for brain protection under deep hypothermic RCP. This study revealed that pH-stat was considered to be better than alpha-stat in terms of CBF and oxygen metabolism in the brain. The regional blood flow distribution was considered to be unchanged irrespective of CO2 management.

Predictive risk factors for delayed extubation in patients undergoing coronary artery bypass grafting

Prolonged mechanical ventilation increases hospitalization costs, airway and lung trauma, and stress. The objective of this study was to elucidate patient characteristics and operative variables that predict delayed extubation in patients undergoing coronary artery bypass grafting (CABG). The records of 167 patients who underwent CABG between 1994 and 1998 were examined retrospectively. The patients were divided into early and delayed extubation groups. Putative factors affecting the duration of intubation were included in a univariate analysis using the t-test and chi-squared test. A logistic regression model was then developed to determine the factors associated with delayed extubation. Forty-four percent of the patients needed prolonged mechanical ventilation (more than 24h). Univariate predictors of delayed extubation (P < 0.05) were emergency surgery, preoperative use of an intra-aortic balloon pump (IABP), the duration of anesthesia, surgery, cardiopulmonary bypass and aortic cross-clamping, the total volume of fentanyl. lowest rectal temperature, glucose level, perioperative transfusion, bleeding, perioperative heart failure, perioperative insertion of IABP, postoperative transfusion, cardiac index, inspired oxygen fraction (FiO2), arterial oxygen tension (PaO2), the PaO2/FiO2 ratio, and the volume of catecholamine. In the delayed extubation group, the intensive care unit stay was significantly longer (P < 0.001) and re-exploration was required more frequently (P = 0.004). Excellent prediction was provided by a model consisting of six variables: age, duration of surgery, perioperative heart failure, glucose level, postoperative transfusion, and the PaO2/FiO2 ratio. These results suggest that decreasing the cardiopulmonary bypass time, maintaining a low glucose level during cardiopulmonary bypass, and ensuring adequate perioperative hemostasis may help to avoid pulmonary dysfunction and delayed extubation. Moreover, the PaO2/FiO2 ratio may be a useful predictor of delayed extubation in patients undergoing CABG.

Effects of recombinant human erythropoietin therapy on blood coagulation and fibrinolysis system

This study was designed to examine the effects of recombinant human erythropoietin (rHuEPO) therapy on blood coagulation and fibrinolysis in patients scheduled for elective heart surgery and undergoing preoperative autologous blood donation. Twenty-seven patients were studied, of whom 16 patients received rHuEPO (group E) and 11 patients no rHuEPO therapy (group N). The patients in group E were given 6000 units of rHuEPO intravenously every other day, three times a week, beginning from two weeks prior to the operation. In both groups, 400 ml of blood was collected preoperatively for predeposit once a week for two weeks, and the self-donated blood was returned to the patient intra- and postoperatively. Blood samples were drawn at the beginning of the study, immediately before the operation and two weeks after the operation. They were analyzed to assess blood coagulation, fibrinolysis, platelet function and vascular endothelial cell function, in order to examine the effects of the administration of rHuEPO. No significant difference was observed between the two groups in the degree of changes in these parameters following the operation. As enhancement of blood coagulability and fibrinolytic activity was evident postoperatively in both groups, changes in these parameters during the preoperative autologous blood donation period were also assessed excluding the postoperative data. Again, there was no significant intergroup difference in any of the markers evaluated. It was concluded that the administration of rHuEPO during preoperative autologous blood donation is unlikely to affect coagulation and fibrinolysis.

Doppler ultrasonographic identification of the critical segmental artery for spinal cord protection

OBJECTIVE

The purpose of this study is to evaluate the possibility of identifying critical segmental arteries (CSAs) based on Doppler ultrasonographic hemodynamics.

METHODS

In 18 mongrel dogs, the descending aorta was scanned directly with a 5-MHz linear probe through left thoracotomies and the flow velocities in segmental arteries were measured by pulsed Doppler. The aorta was cross-clamped between Th13 and L1, and flow velocity changes were recorded. According to flow increases, segmental arteries were divided into three groups: arteries with the largest flow increase (L-arteries), arteries with the smallest increase (S-arteries) and other arteries (O-arteries). Animals were divided into three groups. One aortic segment including an L-artery or an S-artery was perfused via a temporary shunt during 30-min aortic cross-clamping distal to the left subclavian artery (Group L or Group S) and neurological outcomes were compared with those of animals without shunting (Group N) after 24 and 48 h.

RESULTS

L-arteries had significantly larger flow increases than S- and O-arteries (74.3+/-33.8, 20.4+/-9.8 and 33.3+/-17.8 cm/s, P<0.01). In Group N, five of the six animals were completely paraplegic (Tarlov Grade 0) and the other was Grade 1. In Group S, four animals were Grade 4 and two were Grade 0 after 24h. However, two animals showed delayed paraplegia. Therefore, four animals were Grade 0 and two were Grade 4 after 48 h. All animals in Group L were neurologically normal (Grade 4) at both after 24h (vs. Group N, P=0.0013) and 48 h (vs. Group N, P=0.0013; vs. Group S, P=0.019).

CONCLUSIONS

Flow responses to aortic cross-clamping differed among segmental arteries and selective perfusion of L-arteries completely prevented paraplegia. Therefore, L-arteries were considered to be CSAs. Hemodynamic measurement of segmental arterial flow using Doppler ultrasonography could be clinically useful for spinal cord protection during thoracoabdominal aortic surgery.

Hemolysis after mitral valve replacement with mechanical valve prostheses

OBJECTIVE

We evaluated effects of type, size, and orientation of mechanical mitral valve prostheses on hemolysis.

METHODS

Subjects were 84 patients who had undergone mitral valve replacement. Lactate dehydrogenase was mainly used as a marker of hemolysis and was measured before surgery, 1 month after surgery, and in the late postoperative period.

RESULTS

Valves used included 16 Medtronic-Hall, 32 St. Jude Medical, and 36 CarboMedics valves. Medtronic-Hall valves caused less hemolysis than St. Jude Medical or CarboMedics valves in the late postoperative period. This resulted because hemolysis due to Medtronic-Hall valves was more severe 1 month after surgery than in the late postoperative period and because hemolysis due to St. Jude Medical or CarboMedics valves was more severe in the late postoperative period than 1 month after surgery. One reason for this finding is that cardiac output was greater in the late postoperative period than 1 month after surgery, making regurgitation through the pivots of bileaflet valves more severe. The orifice area and the orientation of prostheses did not affect hemolysis.

CONCLUSION

St. Jude Medical or CarboMedics valves caused more severe hemolysis than Medtronic-Hall valves in the late postoperative period.

Indication and perioperative management for cardiac surgery in patients with liver cirrhosis. Our experience with 3 patients

Three patients with noncardiac Child A cirrhosis underwent cardiac surgery. All survived surgery, but 2 died during follow-up periods. A 61-year-old woman who underwent successful double valve replacement died of diabetic coma and severe acidosis due to intestinal necrosis 18 months later. A 57-year-old woman who underwent successful mitral valve replacement died of liver failure induced by heart failure 9 years later. A 45-year-old man who underwent coronary artery bypass grafting is doing well 18 months after discharge. Proper perioperative management, including high-flow cardiopulmonary bypass, pharmacological and mechanical circulatory support, and mechanical respiratory support prevented further, potentially lethal, hepatic dysfunction, leading to good early surgical results. We concluded that patients with Child A cirrhosis could tolerate cardiac surgery. Subsequent surgical results, however, were unsatisfactory, and more careful follow-up is necessary to obtain better late results.

Right heart bypass for left circumflex coronary artery bypass grafting

Displacement of the heart to expose the left circumflex artery (LCX) causes hemodynamic disturbance during off-pump coronary artery bypass grafting (CABG). We applied right heart bypass (RHB) using a heparin-coated centrifugal pump without an oxygenator in an attempt to stabilize the hemodynamics. Five mongrel dogs (15.5-20 kg) were used. Hemodynamic parameters were continuously monitored at a fixed rate of 80 beats/min. The LCX was exposed with the use of an Octopus Tissue Stabilizer. After baseline data were obtained, each dog was placed in the Trendelenburg position. Finally, RHB was established with different pump flows. LCX exposure caused a significant decrease in aortic flow (to 33.1% +/- 13.1% of the baseline value) and arterial mean pressure (to 68.3% +/- 8.5%) (P < 0.001). Trendelenburg positioning caused these values to recover to 57.1% +/- 6.7% and 72.5% +/- 7.7%, respectively. RHB with 50% flow significantly improved the hemodynamic values, although 100% flow significantly increased LAP by 134.8% +/- 19.7% (P < 0.01). Tilting of the canine heart to expose the LCX caused significant deterioration of the hemodynamic values. Trendelenburg positioning was moderately effective, and RHB very effective, in improving the hemodynamics. In a limited number of cases, an appropriate flow of RHB may provide safe hemodynamic assistance during off-pump CABG of the LCX.

Predictive risk factors for pulmonary oxygen transfer in patients undergoing coronary artery bypass grafting

The ratio of arterial oxygen tension to inspired oxygen fraction (PaO2/FiO2) is a useful indicator for weaning patients from mechanical ventilation and a reliable predictor of pulmonary dysfunction after cardiac surgery. The aim of this study was to elucidate the patient characteristics and variables that affect the PaO2/FiO2 ratio. Between 1994-1998, 167 patients who underwent coronary artery bypass grafting (CABG) were examined retrospectively. Spearman's correlation coefficients were calculated between the PaO2/FiO2 ratio and intubation period, and length of ICU stay. Patients were then divided into two groups with a PaO2/FiO2 ratio < 350 and PaO2/FiO2 ratio > or = 350. Univariate analysis of the putative risk factors was performed. A logistic regression model was developed to evaluate factors that would influence the PaO2/FiO2 ratio. A significant correlation was observed between the PaO2/FiO2 ratio and intubation period, and length of ICU stay. Univariate predictors of a PaO2/FiO2 ratio < 350 were low body weight, low preoperative PaO2 long operation time, high FiO2, low postoperative PaO2 history of smoking, hypertension and opening of pleura (p < 0.05). Excellent prediction was found with a model consisting of preoperative PaO2 and hypertension.

CONCLUSION

The results of this study suggest that patients with a low preoperative PaO2 or hypertension may need more careful peri- and postoperative management since these factors are closely associated with the PaO2/FiO2 ratio.

Atrial ablation using an IRK-151 infrared coagulator in canine model

BACKGROUND

A method of atrial ablation was developed with the aim of shortening the aortic cross-clamp time during MAZE surgery. The IRK-151 infrared coagulator (Infrarot-Kontaktkoagulator: MBB: Messerschmidt-Bolkow-Blohn, Germany) was employed. Our aim was to electrophysiologically confirm the efficacy of this device.

METHODS

The MAZE-III procedure was performed in four mongrel dogs. Instead of a pulmonary vein-encircling incision, IRK-151 was applied several times to create a continuously overlapping circular lesion. After aortic declamping, the potentials of both atria were recorded using 18 bipolar electrodes implanted in the atrial wall. The recording conditions were: 1) sinus rhythm, 2) overdrive pacing from outside the encircling coagulation, and 3) overdrive pacing from inside the encircling coagulation.

RESULTS

1) There was no detectable potential within the pulmonary vein-encircling coagulation. 2) There was no conduction of paced atrial potential inside the encircling coagulation. 3) Only the area within the encircling coagulation was activated by the stimulus. Other parts of the atrium showed sinus rhythm simultaneously.

CONCLUSIONS

The left atrium within the pulmonary vein-encircling coagulation was isolated electrophysiologically.

Hypertrophic obstructive cardiomyopathy associated with mitral regurgitation due to infective endocarditis

A 25-year-old woman treated for hypertrophic obstructive cardiomyopathy and suffering from mitral regurgitation due to infective endocarditis was referred to our department for surgery. Preoperative examinations revealed asymmetric septal hypertrophy, a large left ventricular outflow gradient (100 mmHg), and perforation of the anterior mitral leaflet resulting in severe mitral regurgitation. The entire mitral complex was resected and septal myectomy conducted to dilate the left ventricle. A bioprosthetic valve was then implanted. Although postoperative heart failure was severe, cardiac function has gradually recovered. The left ventricular outflow gradient has decreased to 8 mmHg, the diastolic left ventricular diameter has increased from 26 to 30 mm, and her New York Heart Association classification has improved from IV to I.

Three-dimensional computed tomography for reoperative minimally invasive coronary artery bypass

We have been using three-dimensional computed tomography (3-D CT) in reoperative coronary artery bypass grafting performed by using a minimally invasive approach. Preoperative 3-D CT scanning can provide beneficial anatomical information about old patent grafts as well as the internal thoracic artery. Thus a mini-thoracotomy can be created at an optimal site, leaving the old graft untouched, and the length of the harvested internal thoracic artery, necessary for the bypass, can be assessed using this new modality.

Minimally invasive limited pericardiectomy: the hybrid approach

This communication describes our clinical experience with the hybrid method, a video-assisted anterior minithoracotomy approach developed for minimally invasive limited pericardiectomy to treat 8 patients with massive pericardial effusion. The average operating time was 37.2 minutes, and there was no procedure-related morbidity or mortality. The mean follow-up period was 5.6 months, and there have been no recurrences. The hybrid approach can be accomplished irrespective of pleural adhesions. It eliminates the need for hemipulmonary collapse, making it more advantageous than the totally port-access thoracoscopic approach.

Aortobronchial fistula late after transverse arch replacement

We report an unusual case of aortobronchial fistula late after transverse arch replacement caused by the remnant of a temporary bypass near the ascending aorta. In reconstructive surgery of the ascending aorta, antegrade perfusion is preferably performed through a side branch after completion of the distal anastomosis by some surgeons. This report suggests possible risk of a serious late complication unless the side branch is placed and tailored properly.

Right heart mini-pump bypass for coronary artery bypass grafting: experimental study

BACKGROUND

Visualization of the left circumflex arteries during off-pump coronary artery bypass grafting (CABG) causes hemodynamic disturbance. We investigated whether right heart mini-pump bypass (RHB), using a centrifugal pump, improved the safety of this procedure by studying the influences of different heart displacement positions, the Trendelenburg maneuver and RHB on hemodynamics.

METHOD

Hemodynamic parameters in eight mongrel dogs (15.5-20 kg) were continuously monitored at a fixed heart rate of 80 beats/min through a conventional median sternotomy. The posterior descending artery (PDA) and left circumflex artery (LCX) were exposed using an Octopus tissue stabilizer. After evaluating the influence of the Trendelenburg maneuver on hemodynamics, a heparin-coated centrifugal pump without an oxygenator was introduced and the impact of different pump flow volumes was investigated during RHB.

RESULTS

LCX exposure caused significant decreases in aortic flow (to 35. 1+/-12.8%) and arterial mean pressure (to 66.1+/-9.3%) compared with baseline (P<0.001). In contrast to PDA exposure, values remained significantly decreased during the Trendelenburg maneuver. On the contrary, RHB significantly improved the hemodynamic impairments caused by both heart displacement procedures, especially LCX exposure, although 100% pump flow significantly increased left atrial pressure to 131.3+/-19.5% (P<0.01).

CONCLUSION

Exposure of the LCX caused severe hemodynamic deterioration, which was not fully reversed by the Trendelenburg maneuver. In contrast, RHB significantly improved hemodynamics, and therefore this technique can be beneficial for CABG of LCX in the limited cases.

Swinging motion of intimal flap through the aortic valve in acute aortic dissection

The purpose of this article is to present a very rare case of Stanford type A acute aortic dissection featuring a swinging motion of the cylinder-shaped intimal flap through the aortic valve. The patient was a 62-year-old male suffering from severe cardiogenic shock. A transthoracic echocardiogram revealed aortic dissection and severe aortic regurgitation. A transesophageal echocardiogram demonstrated that the aortic dissection in the ascending aorta was circumferential and the proximal portion of the intimal flap was swinging through the aortic valve, ie., falling into the left ventricle during the diastolic phase and being ejected back into the ascending aorta during the systolic phase. An emergency graft replacement of the ascending aorta was performed. During ventricular fibrillation under total cardiopulmonary bypass, we performed cardiac massage to prevent myocardial ischemia, because blood flow from a heart lung machine inverted the intimal flap, which might have disturbed the coronary circulation. The patient's postoperative course was uneventful, and his postoperative echocardiogram revealed only a trace of regurgitant flow through the aortic valve. Back-and-forth movement of the cylinder-shaped intima requires coexistence of the following three conditions: severe aortic regurgitation, circumferential dissection, and complete transection of the intimal flap. We conclude that this movement of the intimal flap should be regarded as one of the most serious complications leading rapidly to cardiogenic shock. From a surgical point of view, it is most important to prevent myocardial ischemia during cardiopulmonary bypass especially in cases in which ventricular fibrillation has occurred. We describe the ways to prevent myocardial ischemia in this rare situation.

Cardiac function evaluated by transesophageal echocardiography during cardiopulmonary bypass

OBJECTIVE

To evaluate cardiac function at cardiopulmonary bypass weaning, we applied a new technique clinically to determine the approximated Emax without using a conductance catheter.

METHODS

Subjects were 5 patients. The left ventricular end-systolic pressure was obtained by overlaying the radial arterial pressure curve on the left ventricular pressure curve. Left ventricular end-systolic volume was assessed by a transesophageal echographic apparatus. At cardiopulmonary bypass weaning, volume loading was applied to increase left atrial pressure by a few mmHg while fixing the pump flow rate at half flow. Changes in left ventricular end-systolic volume and approximated left ventricular end-systolic pressure for total heart beat were plotted during this period, and the gradient of the regression line was taken as approximated Emax.

RESULTS

Approximated Emax ranged from 1.29 to 3.28 (mean 2.13 +/- 0.72), and its correlation coefficient was 0.80 +/- 0.06.

CONCLUSION

Our new technique is useful in evaluating cardiac function during cardiopulmonary bypass.

[Recent donation and clinical results of homograft tissue]

Between August 1995 and July 1999, we have experienced 14 donors for allografts (mean age: 39.8 +/- 15.8, M/F = 10/4, mean warm ischemic time: 359 minutes). Donated tissues were included 12 aortic valves and 12 pulmonary valves, respectively. Since February 1994, clinical diagnoses of 14 patients included 7 congenital heart disease, 5 infective heart disease, 1 artificial graft infection, and 1 thrombosed valve. There was no graft-transmitted disease. In congenital heart disease, 3 patients (HLHS: 1, Truncus: 1, TOF + PA: 1) died (early mortality, 42%) and 1 with TGA had residual conduit stenosis. However, in infective heart disease, all patients survived without recurrent infection and did not need reoperation (early mortality, 0%). Our clinical results of homograft implantation for infective heart disease were excellent, but more careful consideration will be needed for congenital heart disease in neonates and/or patients with poor preoperative condition.

Upper hemisternotomy as conversion from minimally-invasive coronary artery bypass grafting

A seventy-year-old man was admitted to hospital for ischemic heart disease and abdominal aortic aneurysm. In the cardiac procedure, we employed a technique for conversion from minimally invasive coronary artery bypass grafting. This technique entailed cardiopulmonary bypass using standard instruments and technique, and the exposure for grafting was the same as for the simple minimally-invasive coronary artery bypass grafting. Moreover, the incision we reported in this case was simply extendable even to a full sternotomy if necessary.

Ultrasonic coagulator for video-assisted internal mammary artery harvest

BACKGROUND

The Harmonic Scalpel (HS; Ethicon Endo-Surgery, Cincinnati, OH, USA) is an ultrasonic coagulator that generates less heat than electrocautery. We compared canine internal mammary arteries (IMAs) harvested using the HS or electrocautery and reviewed the early clinical outcome after thoracoscopic IMA takedown with the HS.

METHODS

Using HS and bipolar electrocautery (BE), 51 and 49 IMA branches, respectively, in six mongrel dogs were divided. The divided branches were subjected to a pressure tolerance test. The impact of coagulation on the main trunk was investigated microscopically. Thoracoscopic IMA harvesting with the HS was performed in 41 patients. Seven human IMA segments including 10 branches were examined microscopically. Postoperative angiography of 40 IMA grafts (97.6%) was performed.

RESULTS

All the IMA branches withstood intraluminal pressures up to 250 mmHg. With BE, coagulation reached the adventitia of the main trunk in six segments (12.2%), but the HS caused no injury. Thoracoscopic IMA harvesting with excellent hemostasis was achieved using only the HS in all 41 patients. The main trunks of the human IMA segments were microscopically intact, and postoperative angiography demonstrated that the IMA grafts were intact.

CONCLUSION

The HS appears to be a reliable coagulator for thoracoscopic IMA harvesting with minimal damage.

Estimation of functional liver reserve in patients before cardiac surgery using antipyrine plasma clearance test

BACKGROUND

Hyperbilirubinemia is not uncommon and is sometimes fatal after valvular surgery. One important cause of it is a poor functional liver reserve, however, conventional tests reflect hepatic blood flow and do not offer precise evaluation of the pure functional liver reserve. Antipyrine has particular pharmacological properties, and its plasma clearance represents quantitatively the functional capacity of the liver. In this study, we measured antipyrine plasma clearance in cardiac surgical patients and evaluated the feasibility of using this parameter as a predictor of the risk of postoperative hyperbilirubinemia.

METHODS

The plasma clearance of antipyrine was measured preoperatively in 40 cardiac patients undergoing mitral and/or tricuspid valvular surgery and its relations with hemodynamics or postoperative course were studied.

RESULTS

Antipyrine clearance in preoperative patients was 0.365+/-0.175 (mean +/- SD) ml/min/kg, lower than the normal range (0.405+/-0.04 ml/min/kg), and showed no correlation with cardiac index, while the plasma disappearance rate of indocyanine green depended on the cardiac index. The maximum postoperative total bilirubin level showed significant correlation with antipyrine clearance (r=-0.699); this correlation coefficient was greater than that with indocyanine green (-0.477). The correlation was more prominent in patients with cardiac dysfunction. Furthermore, antipyrine clearance showed significant predictability of the duration of ICU stay.

CONCLUSIONS

Antipyrine clearance provides a precise estimate of functional liver reserve which is independent of hemodynamics and predicts the risk of postoperative hyperbilirubinemia in preoperative cardiac patients.

Application of AdvaSeal for acute aortic dissection: experimental study

BACKGROUND

In the surgical treatment of acute aortic dissection, intractable hemorrhage often occurs. We performed an animal study to test the hypothesis that a new sealant, AdvaSeal (Ethicon Inc, Johnson & Johnson Medical KK, Somerville, NJ), can close the false channel of aortic dissection.

METHODS

Acute descending aortic dissection was created surgically in 12 mongrel dogs. In 7 of these (treated group), AdvaSeal was applied to the false cavity for reinforcing and fusing the dissected layers and also to the suture line. The other 5 dogs (control) were left untreated. Specimens were harvested 2 weeks after surgery.

RESULTS

The sealant could be used in wet conditions. In the treated group, hemostasis was easily achieved during surgery. All false cavities were perfectly thrombosed, causing no deleterious effects related to the sealant. In the control group, all false lumina remained patent.

CONCLUSIONS

The advantage of AdvaSeal was its effectiveness on wet tissue and its adhesiveness, allowing good hemostasis and closure of the false lumen. The sealant can be an easy and efficacious sealant in treatment for acute aortic dissection.

Management of severe acute pancreatitis with a somatostatin analog in a patient undergoing surgery for dissecting thoracic aneurysm: report of a case

A patient who was admitted to our hospital to undergo surgery for a dissecting thoracic aneurysm suffered preoperatively from severe acute pancreatitis with pancreatic pseudocysts. Computerized tomography (CT) demonstrated the presence of new fluid collection around the cyst with the absence of pancreatic necrosis. He was given a somatostatin analog (sandostatin), which was effective in decreasing the abdominal symptoms, leukocyte counts, and the serum C-reactive/protein level. A CT scan revealed that the pancreatic pseudocyst and peripancreatic fluid collection had disappeared. Although somatostatin has been reported to be ineffective for acute pancreatitis with necrosis, pancreatitis without necrosis may regress after treatment with sandostatin. This is probably due to its suppressive effect on the exocrine function, thus resulting in a decrease of pancreatic juice infiltration.

Hemodynamic effects of carbon dioxide insufflation under single-lung ventilation during thoracoscopy

BACKGROUND

The hemodynamic effects of carbon dioxide insufflation under single-lung ventilation were studied in 22 consecutive thoracoscopic harvests of the left internal mammary artery, which was used for minimally invasive coronary artery bypass grafting.

METHODS

An electrocardiograph, arterial catheter, Swan-Ganz catheter, and transesophageal echocardiograph were used to monitor seven hemodynamic variables. Baseline data were obtained during ventilation of both lungs and the measurements were repeated after the left lung was collapsed and at 5 and 30 minutes after hemithorax insufflation with low-flow (2 to 3 L/minute) carbon dioxide gas was begun. The intrapleural pressure was maintained at 8 to 10 mm Hg.

RESULTS

Thoracoscopic harvest of the internal mammary artery was completed in all cases with a mean insufflation time of 44+/-12 minutes. There were no significant changes in the mean arterial pressure, heart rate, cardiac index, and left ventricular ejection fraction throughout the procedure, whereas the central venous pressure, mean pulmonary arterial pressure, and pulmonary capillary wedge pressure (p < 0.05 for each variable) during insufflation.

CONCLUSIONS

Low-flow carbon dioxide insufflation into the left hemithorax with an intrapleural pressure of 8 to 10 mm Hg under selective right-lung ventilation does not compromise the human heart with normal to moderately depressed function and can be an efficacious adjunct in specific thoracoscopic procedures.

Intravalvular implantation technique for aortic valve replacement in aortitis syndrome

BACKGROUND

Paravalvular leakage is one of the most serious complications of aortic valve replacement in patients with aortitis syndrome. The purpose of this study was to compare the effectiveness of the intravalvular implantation technique in preventing paravalvular leakage with that of the conventional technique.

METHODS

Since 1982, 14 patients with aortic regurgitation caused by aortitis syndrome have undergone aortic valve replacement at our institute. An intravalvular implantation technique was applied in 7 of the 14 patients. The technique consists of suturing a prosthetic valve to the aortic annulus and sandwiching the leaflets between exogenous felt pledgets and the inflamed aortic annulus.

RESULTS

Paravalvular leakage occurred in 3 of 7 patients in the conventionally treated group and in none of 7 in the intravalvular implantation group.

CONCLUSIONS

The intravalvular implantation technique is effective in preventing paravalvular leakage in patients with aortitis syndrome.

Atrial ablation with an IRK-151 infrared coagulator

BACKGROUND

The purpose of this study was to develop a method of atrial ablation. In the IRK-151 infrared coagulator, light from a tungsten-halogen lamp is focused into a quartz rod. The distal exit plane is connected to a tip made of sapphire to allow linear ablation.

METHODS

Thirty-six lesions were created in 9 mongrel dogs. The beating ventricular myocardium was ablated from the epicardium. In each dog, 4 lesions were created by using the following durations of application: 3, 9, 15, and 21 seconds. After the ablation, the myocardium was fixed and stained. A linear lesion on the beating right atrial free wall was created. Before and after the ablation, epicardial plaque-electrode mapping was performed. Three months after ablation, remapping was performed.

RESULTS

The ablated myocardium had well-demarcated necrosis without carbonization or vaporization. The maximum depth was 10.3 +/- 0.8 mm. The conducting pathway was blocked. The block, once made, continued for 3 months.

CONCLUSIONS

The IRK-151 produces well-demarcated lesions that were deep enough for atrial ablation to block the conducting pathway.

[Snare injury in coronary artery bypass grafting on the beating heart: report of 2 cases]

From June to November 1997, 8 patients underwent coronary artery bypass grafting on the beating heart. The first 2 patients had snare injury. Postoperative angiography showed coronary stenosis distal to the LITA-LAD anastomosis in the first case and a pseudo-aneurysm at the septal branch of the LAD in the second case, most likely due to snaring maneuver with 3-0 prolene or 3-0 GORE-TEX suture with a sharp needle. Since then, we have been satisfactorily utilizing the RETRACT-O-TAPE (a silicone tape with blunt needle, QUEST Medical, Inc.) for coronary occlusion to avoid injury to the native vessels and their branches.

[Video-assisted MICABG for the patient with right mammary carcinoma--a case report]

A 69-year-old female with advanced right mammary carcinoma presented to us with diffuse stenosis of the proxymal left anterior descending artery (LAD). Right mastectomy had been suspended. The LAD was treated with minimally invasive CABG (MICABG) assisted with a thoracoscopic procedure. The left internal thoracic artery (LITA) was taken down through thoracoscopy from the upper margin of the 1st rib to the lower margin of the 5th rib using only the Harmonic Scalpel (Ethicon Endo-Surgery). Coronary anastomosis to the LAD was completed without cardiopulmonary bypass through a small thoracotomy on the anterior 4th intercostal space. The operation time was 4 h 30 min and the blood loss was 120 ml. Post operative course was uneventful. Doppler study and angiography demonstrated patent LITA to the LAD. Right mastectomy was achieved 29 days after MICABG. MICABG can be a veneficial alternative method for the patient with malignant disease, allowing quick convalescence and early cancer operation. Thoracoscopy allows for sufficient LITA harvest up to the 1st rib or higher with the Harmonic Scalpel.

[Open heart surgery in patients with a tracheostoma]

From April 1992 to May 1997 six patients underwent open heart surgery, who had tracheostoma at the time of operation. The sternum was divided completely in three patients whose tracheostoma lay highly on the neck, and it was cut transversely on the manubrium at the level of the first intercostal space, below which it was split longitudinally in two patients (partial median sternotomy). In one patient right anterolateral thoracotomy was used. There were no operative death and no complication related to infection. A left internal thoracic artery (LITA) was used successfully for a bypass conduit in two patients who underwent partial median sternotomy. Dissection of the proximal portion of the LITA through the second intercostal space prior to the sternotomy made the graft procurement feasible in this particular situation. In conclusion, full-length sternotomy is performable safely when the tracheostoma lies highly on the neck, and the partial sternotomy up to the midmanubrium is applicable, including LITA harvesting, even if it is just at the sternal angle.

Persistent hemolysis after coil occlusion of a patent ductus arteriosus in a patient with aortic regurgitation

We report a rare case of hemolysis after coil occlusion of a patent ductus arteriosus (PDA), which was treated by surgical removal of the coil and closure of PDA. A 65-year-old woman was admitted to our hospital with congestive heart failure due to severe aortic regurgitation associated with PDA. Before undergoing open heart surgery she underwent closure of the PDA using a Jackson coil as an adjunct of treatment to improve her hemodynamic state. However, a small residual shunt resulted in severe hemolysis. Two weeks after the intervention she underwent aortic valve replacement and PDA closure after removal of the coil through the main pulmonary artery under moderate hypothermia and temporary circulatory arrest. Hemolysis is always secondary to a residual leak and several methods have been reported to manage this complication. Our report suggests that early surgical retrieval of the coil before the organized thrombus is formed, can be safely performed even in an elderly patient whose ductus is usually fragile.

[Atrial septal defect and severe pulmonary hypertension in an adult who needed nitric oxide inhalation after repair]

A 51-year-old male was diagnosed as having an ostium secundum atrial septal defect with severe pulmonary hypertension. Although pulmonary artery pressure was as high as 96/32 and pulmonary vascular resistance was 14.2 U.m2, he underwent corrective surgery, because pulmonary to systemic blood flow ratio was 2.0. After he regained consciousness in ICU, pulmonary hypertensive crises recurrently occurred and the hemodynamics became quite unstable. Administration of conventional drugs proved to be ineffective. Since inhalation of low dose (3-4 ppm) nitric oxide was started, however, his condition was markedly improved and he recovered uneventfully thereafter. Two years later, pulmonary artery pressure was reduced to 52/28 and pulmonary vascular resistance was 9.9 U.m2. Although good outcome can not be expected in all surgically treated cases, we should refrain from deciding easily that surgery is contraindicated, because no criteria of surgical indication for atrial septal defect with pulmonary hypertension appears to be perfect.

Coronary artery bypass grafting by median sternotomy in patients with a tracheostoma

The approach to the heart for open heart surgery in patients with a tracheostoma requires careful consideration. The presence of a tracheostoma interferes with the standard sternotomy and increases the risk of mediastinitis. We have successfully performed coronary artery bypass grafting in two patients with a tracheostoma using the limited median sternotomy and describe the surgical procedure used in these patients.

[Cardiac surgery in Jehovah's Witness]

Clinical experiences of 35 cardiothoracic operations in Jehovah's Witness patients were presented with special reference to a method of taking informed consent for surgery. At first the surgeon explained the details of the proposed surgery including its risks and benefits. He should also express his confidence in accomplishing the operation without blood transfusion. Otherwise he should not dare to perform the operation. The surgeon asked the patient to talk about his or her religious belief in transfusion denial. Then the surgeon was allowed to talk about his professional duty and ethical belief in saving the patient at all costs. Finally, both the patient and the surgeon would sign the document of informed consent without fully determining whether or not the patient would undergo transfusion at an unexpected situation since the possibility of such unexpected necessity of blood transfusion was believed extremely low by both the surgeon and the patient. The trust of the patient in the technique of the surgeon was the key to this agreement.

Repair of ruptured anastomotic aneurysm: elephant trunk technique after endovascular covered stents

Endovascular covered stents were successfully applied to temporarily halt hemoptysis and postpone surgical intervention in a 69-year-old man with a ruptured anastomotic false aneurysm of the distal aortic arch. Surgical graft implantation was performed successfully by the elephant trunk technique 14 days after the endovascular stent-grafting, at which time aspiration pneumonia had subsided.

Mitral valve repair through combined left atrial and ventricular approach for congenital mitral stenosis

A 3-year-old boy underwent mitral valve repair for congenital mitral stenosis through combined superior-septal atriotomy and apical left ventriculotomy. The operation was performed safely with excellent exposure of the subvalvular apparatus by the ventricular approach, while sufficient visualization of the valvular lesion was obtained by the atrial approach. Postoperative echocardiography demonstrated normal left-ventricular motion and no residual mitral stenosis.

Mitral valve repair with extensive resection of the anterior leaflet for regurgitation due to Barlow's disease. Report of a case

We recently performed mitral valve repair for a case of mitral regurgitation due to Barlow's disease, which is relatively rare in Japan. Both the anterior and posterior leaflets were affected by advanced myxomatous change, and appeared markedly thickened and redundant. Although extensive resection of the anterior leaflet is not a generally accepted method, nearly one fourth of the anterior leaflet was resected in this case. Now, at 36 months after the operation, there is only trivial regurgitation and the patient is doing well and without symptoms. We believe that extensive resection of the anterior leaflet can be a useful treatment for repair of a redundant anterior leaflet with excess tissue.

[Reoperation for relief of valvular and supravalvular stenosis late after aortic valve replacement with Manouguian's anulus enlargement: report of a case]

Thirteen year-old boy who received aortic valve replacement with Manouguian's anulus enlargement for congenital aortic stenosis 7 years ago developed valvular and supravalvular stenosis. Pressure gradient between left ventricle and aorta was 55 mmHg. The etiology of supravalvular stenosis was extensive patch plasty of ascending aorta and severe degeneration of expanded polytetrafluoroethylene patch. Moreover, white hard mass existed just outside the patch and was one of the components of the stenosis. This mass was acellular calcification without foreign body reaction. Degenerated prosthetic patch was thoroughly resected, and redo Manouguian's procedure with autogeneous pericardium was performed. We tried to use two sizes larger 21 mm valve, but, after all, 19 mm valve was sewn into place. His postoperative course was uneventful.