[Efficacy of modified ultrafiltration in coronary artery bypass grafting]

We evaluated the efficacy of modified ultrafiltration (MUF) in coronary artery bypass grafting. Twenty patients were divide into two groups consisting of a control group (n = 11) and a MUF group (n = 9). MUF was carried out for fifteen minutes immediately after the completion of cardiopulmonary bypass. The blood flow through the ultrafilter was 300 ml/min and about 1,200 ml of water was removed. The hematocrit elevated significantly from 25% to 30% in the MUF group (p < 0.01). Postoperative blood loss in the first 24 hours in the MUF group was significantly less than that in the control group (8 +/- 2 ml/kg vs 12 +/- 4 ml/kg, p < 0.01). There was no statistical difference in the percentage of the increase in body weight after the operation, inflammatory reaction and pulmonary function (A-a DO2, PaO2/FIO2 and duration of intubation) between two groups. In conclusion, MUF is useful to hemoconcentrate and reduce postoperative blood loss in coronary artery bypass grafting.

[Efficacy of modified ultrafiltration in reoperation for valvular disease]

We evaluated the efficacy of modified ultrafiltration (MUF) in reoperation for valvular disease. Fourteen patients were divide into two groups consisting of a control group (n = 6) and a MUF group (n = 8). MUF was carried out for fifteen minutes immediately after the completion of cardiopulmonary bypass. The blood flow through the ultrafilter was 300 ml/min and about 1,200 ml of water was removed. The hematocrit elevated significantly from 25% to 31% in the MUF group (p < 0.05). The percentage of the increase in body weight after the operation in the MUF group was significantly less than that in the control group (3.3 +/- 3.1% vs 8.3 +/- 4.3%, p < 0.05). The PaO2/FIO2 after the operation in the MUF group was significantly higher than that in the control group (376 +/- 125 mmHg vs 242 +/- 79 mmHg, p < 0.05). The duration of mechanical ventilation in the MUF group was significantly less than that in the control group (1.1 +/- 1.1 days vs 5.3 +/- 3.3 days, p < 0.05). In conclusion, MUF is useful to hemoconcentrate, reduce postoperative body weight gain and promote early recovery of pulmonary function in reoperation for valvular disease.

Concomitant replacement of the aortic root and aortic arch with or without secondary thoracoabdominal aorta replacement

OBJECTIVES

Extensive aortic replacement, such as concomitant aortic root and arch replacement, thoracoabdominal aortic repair, and complete thoracic aorta replacement, remains controversial. We studied surgical morbidity and mortality in patients undergoing concomitant aortic root and arch replacement, and those undergoing secondary replacement of the thoracoabdominal aorta after this preceding procedure.

SUBJECTS AND METHODS

Between January, 1987 and March 1999, 21 patients (mean age: 52 years) underwent concomitant aortic root and arch replacement involving 3 surgical procedures--aortic root replacement with composite graft and arch (n = 12), aortic root replacement with valve sparing and arch (n = 4), or aortic root replacement with composite graft and arch and elephant trunk (n = 5).

RESULTS

Overall hospital mortality was 4.8%. Six patients (mean age: 42 years) underwent secondary thoracoabdominal aorta replacement after the concomitant root and arch procedure. The mean time until secondary surgery was 9.5 months. There was 1 hospital death.

CONCLUSION

Concomitant replacement of the aortic root and arch, or secondary replacement of the thoracoabdominal aorta after concomitant root and arch replacement can be conducted with low surgical morbidity and mortality.

Opening of potassium channels protects mitochondrial function from calcium overload

Ischemic preconditioning (IPC) protects myocardium from ischemia reperfusion injury by activating mitochondrial K(ATP) channels. However, the mechanism underlying the protective effect of K(ATP) channel activation has not been elucidated. It has been suggested that activation of mitochondrial K(ATP) channels may prevent mitochondrial dysfunction associated with Ca(2+) overload during reperfusion. The purpose of this experiment was to study, in an isolated mitochondrial preparation, the effects of mitochondrial K(ATP) channel opening on mitochondrial function and to determine whether it protects mitochondria form Ca(2+) overload. Mitochondria (mito) were isolated from rat hearts by differential centrifugation (n = 5/group). Mito respiratory function was measured by polarography without (CONTROL) or with a potassium channel opener (PINACIDIL, 100 microM). Different Ca(2+) concentrations (0 to 5 x 10(-7) M) were used to simulate the effect of Ca(2+) overload; state 2, mito oxygen consumption with substrate only; state 3, oxygen consumption stimulated by ADP; state 4, oxygen consumption after cessation of ADP phosphorylation; respiratory control index (RCI: ratio of state 3 to state 4); rate of oxidative phosphorylation (ADP/Deltat); and ADP:O ratio were measured. PINACIDIL increased state 2 respiration and decreased RCI compared to CONTROL. Low Ca(2+) concentrations stimulated state 2 and state 4 respiration and decreased RCI and ADP:O ratios. High Ca(2+) concentrations increased state 2 and state 4 respiration and further decreased RCI, state 3, and ADP/Deltat. PINACIDIL improved state 3, ADP/Deltat, and RCI at high Ca(2+) concentrations compared to CONTROL. Pinacidil depolarized inner mitochondrial membrane, as evidenced by decreased RCI and increased state 2 at baseline. Depolarization may decrease Ca(2+) influx into mito, protecting mito from Ca(2+) overload, as evidenced by improved state 3 and RCI at high Ca(2+) concentrations. The myocardial protective effects resulting from activating K(ATP) channels either pharmacologically or by IPC may be the result of protecting mito from Ca(2+) overload.

[Recent surgical treatment for patients with true aortic arch aneurysm]

From december 1996 to april 1999, 25 patients with true aortic arch aneurysm underwent aortic arch aneurysm repair using selective cerebral perfusion. There were 17 males and 8 females ranging in age from 62 to 79 years (mean 71 years). Orikaesi method was used in the procedure of distal anastomosis for complete aortic arch replacement with a prosthetic graft. This technique allowed us a simple approach to the lesion and the easy additional stitch. The average duration of extracorporeal circulation, aortic crossclamping, selective cerebral perfusion were 269 minutes, 140 minutes, and 122 minutes, respectively, under 19.3 degrees C of lowest esophageal temperature. There were no cases complicated with postoperative low output syndrome and cerebrovascular accident, and no hospital mortality. Replacement of the aortic arch using selective cerebral perfusion is a safe procedure with acceptable hospital mortality.

Bioenergetic effect of liposomal coenzyme Q10 on myocardial ischemia reperfusion injury

The antioxidant and bioenergetic effects of CoQ10 are well known but its clinical utility is limited by the requirement for enteral administration. A newly developed liposomal CoQ10 (CoQ) is water soluble and capable of intravenous administration. The purpose of this study is to determine the mechanism by which acute administration CoQ protects myocardium from reperfusion (Rp) injury. Rats were pretreated with CoQ 10 mg/kg i.v. 30 min prior to the experiment. Control rats were pretreated with liposome only. Hearts were excised and subjected to equilibration, 25 min of normothermic ischemia and 40 min of Rp on a Langendorff apparatus. At end Rp, CoQ hearts recovered 74 +/- 5% of their DP vs. 50 +/- 9% in control (p < 0.05). Aerobic efficiency was maintained (0.66 +/- 0.02 vs. control, 0.5 +/- 0.04, p < 0.003) and CoQ hearts lost less CK activity vs. control (p < 0.02). PCr and ATP were higher than control (p < 0.05, 0.02, respectively). Results show that i.v. CoQ improves recovery of function, aerobic efficiency, CK activity, and recovery of PCr and ATP after Rp. This suggests that acute administration of liposomal CoQ improves myocardial tolerance to I/R via its role as an antioxidant as well as improving oxygen utilization and high energy phosphate production.

Acute administration of liposomal coenzyme Q10 increases myocardial tissue levels and improves tolerance to ischemia reperfusion injury

The antioxidant and bioenergetic effects of CoQ10 (CoQ) suggest it might be ideal therapy for acute myocardial ischemia. Its utility is limited by the requirement for enteral administration. This study related the administration of a new liposomal suspension of CoQ given intravenously to (1) serum and myocardial [CoQ] and (2) recovery of function, myocardial efficiency, and oxidant injury after cardiac ischemia and reperfusion (I/R). Rats (n = 8/group) were given liposomal CoQ 10 mg/kg iv or placebo (Control), 15 min (C-15), 30 min (C-30), and 60 min (C-60) before (1) measurement of serum and myocardial CoQ or (2) Langendorff perfusion of hearts subjected to 15 min equilibration, 25 min ischemia (37 degrees C), and 40 min reperfusion (RP). Developed pressure (DP) was measured via an intraventricular balloon and coronary flow was measured by a digital flow meter. Myocardial efficiency was defined as DP/MVO2 where MVO2 = microl O2 consumed/min/gram LV. At end RP hearts were assayed for CK, an oxidant sensitive enzyme. Maximum preischemic CoQ levels in serum and myocardium occurred 15 and 30 min after administration, respectively. At end reperfusion, C-30 hearts improved the most, recovering 75 +/- 4% of their preischemic DP while Control recovered only 52 +/- 6% (P < 0.03) as well as maintaining better myocardial efficiency (0.69 +/- 0.02 vs Control, 0.43 +/- 0.05) (P < 0.001). C-15, C-30, and C-60 groups all lost less CK activity after RP vs Control (P < 0.04).

CONCLUSION

(1) Serum and myocardial levels of CoQ can be raised acutely by iv liposomal CoQ. (2) Myocardial CoQ levels correlate best with I/R protection. (3) Acute iv CoQ improves function and efficiency and decreases oxidant injury after I/R. Intravenous CoQ may be effective clinically for acute cardiac ischemic syndromes.

[Early and late results of replacement of the ascending aorta and/or aortic arch using selective cerebral perfusion]

From 1987 to 1994, 116 patients received replacement of the ascending and/or aortic arch using selective cerebral perfusion. They were 82 male and 34 female, with average age of 64 years. There were 63 dissecting and 53 true aneurysms. Extent of replacement was: ascending aorta in 13, aortic root in 2, aortic arch in 93, and aortic root and complete arch in 8. Aortic arch replacements were composed of: 29 partial proximal aortic arch replacements, 44 complete aortic arch replacements, and 20 partial distal aortic arch replacements. Nineteen (16.4%) hospital deaths occurred. Univariate testing of pre-, intra-, and post-operative variables followed by stepwise logistic regression analyses identified elderly, ischemic heart disease, postoperative neurologic complication, cardiac dysfunction, renal failure, and massive bleeding as factors having independent association with hospital mortality. Neurologic complication was found in 10 patients (8.6%), and risk factor for this complication was preoperative peripheral vascular disease. Follow-up of hospital survivors documented an overall cumulative 5-year survive rate of 69%. There was no significant difference between dissection and true aneurysms in 5-year survive ratios, which were 63% and 82%, respectively. During follow-up periods, 18 patients died. Half of these cases were vascular deaths, caused by rupture, sudden death and secondary operation. Univariate analyses followed by stepwise Cox testing indicated that chronic obstructive pulmonary disease and a history of postoperative massive bleeding were associated with decreased later survival. Our experience suggests that selective cerebral perfusion is a safe technique for the repair of ascending aorta and/or aortic arch problems. High-risk subgroups of patients with these aortic problems can be identified by risk factors. Aggressive and careful management is necessary for such subgroups to improve early and late survival rates.

[Redo operation after surgery for aortic aneurysm and dissection]

Thirteen patients who underwent redo operation after surgical treatment of aortic aneurysm and dissection were presented. In 8 patients, redo operations were performed for aortic dissection following aortic valve replacement. A-C bypass, the Koster-Collins operation and replacement of thoracic aorta. In the other 5 patients, the reasons for redo operation were aortic root enlargement after replacement of ascending aorta and aortic valve replacement, pseudoaneurysm and aneurysmal dilatation around coronary button for the Bentall operation and recurrent aneurysm after patch aortoplasty and thoracoabdominal replacement using the Crawford's maneuver. To prevent these redo operation, adequate selection of surgical procedures and meticulous operative techniques should be required in primary operation.

The mechanisms of coenzyme Q10 as therapy for myocardial ischemia reperfusion injury

It has been hypothesized that CoQ10 (CoQ) pretreatment protects myocardium from ischemia reperfusion (I/R) injury by its ability to increase aerobic energy production as well as its activity as an antioxidant. Isolated hearts from rats pretreated with either CoQ 20 mg/kg i.m. and 10 mg/kg i.p. or vehicle 24 and 2 h prior to the experiment, were subjected to 15 min of equilibration (EQ), 25 min of ischemia, and 40 min of reperfusion (RP). Developed pressure, +/-dp/dt, myocardial oxygen consumption, and myocardial aerobic efficiency (DP/MVO2) were measured. 31P NMR spectroscopy was used to determine ATP and PCr concentrations. Lucigenin-enhanced chemiluminescence of the coronary sinus effluent was utilized to determine oxidative stress through the protocol. CoQ pretreatment improved myocardial function after ischemia reperfusion. CoQ pretreatment improved tolerance to myocardial ischemia reperfusion injury by its ability to increase aerobic energy production, and by preserving myocardial aerobic efficiency during reperfusion. Furthermore, the oxidative burst during RP was diminished with CoQ. Similarly it was hypothesized that CoQ protected coronary vascular reactivity after I/R via an antioxidant mechanism. Utilizing a newly developed lyposomal CoQ preparation given i.v. 15 min prior to ischemia, ischemia reperfusion was carried out on Langendorff apparatus as previously described. Just prior to ischemia and after RP, hearts were challenged with bradykinin (BK) and sodium nitroprusside (SNP) and change in coronary flow was measured. CoQ pretreatment protected endothelial-dependent and endothelial-independent vasodilation after I/R. We conclude that CoQ pretreatment protects coronary vascular reactivity after I/R via OH radical scavenger action.

[Separate perfusion of upper and lower body under mild hypothermia during operation on the thoracoabdominal aorta]

During last 7 years, we performed 24 operations on the thoracoabdominal aorta. There were 9 true and 15 dissecting aneurysms. There were two cases of ruptured aneurysm and thoracoabdominal replacement was performed as a last stage operation for total aortic replacement in 4 cases. Three cases with aortic dissection died within 30 days after surgery. Femoro-femoral bypass was used in 4 cases (1 case died of brain damage, paraplegia and MOF), left heart bypass in 5 cases and separate perfusion of upper and lower body (SPULB) under deep hypothermia in 7 cases (2 cases died of LOS and cerebrovascular accident occurred at 2 weeks after operation) and SPULB with mild hypothermia in 8 cases for circulatory support. There was one case of renal dysfunction and transient mild liver dysfunction occurred in 7 cases. There was no evidence on relationship between surgical outcome and methods of circulatory supports, but we recently prefer SPULB under mild hypothermia for thoracoabdominal surgery since intraoperative massive bleeding and cardiac arrest can be easily treated and major organs can be protected by introducing hypothermia in this perfusion technique.

Diverticulum of the superior vena cava

A 14-year-old girl underwent operation with the diagnosis of diverticulum of the superior vena cava. Microscopic findings revealed a diverticulum with venous architecture. This represents a rare case of a giant diverticulum of the superior vena cava.

[The effect of preclotting and collagen coating on endothelializing rate and thrombogenesity of Dacron grafts in the canine thoracic aorta]

Although high porosity knitted Dacron is generally recognized to have superior healing characteristics over woven Dacron, its porosity must be controlled at the clinical operation. This can be achieved with several materials, including geratin, insoluble collagen, albumin, and fibrin. We made atherocollagen coated graft using EX-313 as a new crosslinking agent. The purpose of this study is to compare the endothelializing rate and thrombogenesity of Dacron grafts coated by atherocollagen in the canine thoracic aorta with preclotting grafts with blood or albumin. Five groups were studied: Control group (n = 10), without preclotting; A-P group (n = 8), preclotting with albumin; B-P group (n = 5), preclotting with blood; W-C group (n = 5), atherocollagen coating with low cross-linkage; S-C group (n = 7), atherocollage coating with high cross-linkage. Thoracic aorta was replaced with 8 mm graft in length of 5.0 to 5.5 cm using temporary bypass with anthron tube. Grafts were harvested 3 months following implantation, and the endothelized surface ratio was calculated by microscopic line sampling method. Endothelized surface ratio of Control group, A-P group B-P group, W-C group and S-C group were 85%, 55%, 67%, 93% and 85%, respectively. Endothelized surface ratio of W-C group and S-C group were higher (p < 0.05) than those of A-P group, B-P group. There were thrombus in non-epithelized area. We conclude that atherocollagen coated graft had superior antithrombogenesity compared to albumin or blood preclotting graft.

Protection from postischemic spinal cord injury by perfusion cooling of the epidural space

To avoid devastating spinal cord injury during aneurysm operations, we evaluated the protective effects of epidural space perfusion cooling during occlusion of the descending thoracic aorta in a canine model. Sixteen dogs were divided into three groups: group 1 (n = 5) underwent 60 minutes of aortic occlusion without epidural space perfusion cooling; group 2 (n = 6), 60 minutes of occlusion with perfusion cooling; and group 3 (n = 5), 120 minutes of occlusion with perfusion cooling. The development of motor disturbance and its severity were examined 7 days after the procedure. In group 1, 1 dog was normal and 4 dogs showed spastic paraplegia with rigidly extended hind limbs. In group 2, 5 dogs were normal and 1 dog was unable to walk although it could move both of its hind legs slightly. In group 3, all 5 dogs were normal. Groups 2 and 3 had a significantly better neurologic outcome than group 1. Histologic examination of the spinal cord in dogs with paraplegia revealed degeneration of gray matter with macrophage infiltration. Histologic examination of the spinal cord in dogs without neurologic deficit showed enlargement of the central canal, light edema, and a small number of dark neurons. We conclude that epidural space perfusion cooling is effective in reducing the incidence of spinal cord injury after temporary occlusion of the descending thoracic aorta.

Replacement of the transverse aortic arch for type A acute aortic dissection

Surgical treatment of acute aortic dissection involving the segment of transverse aortic arch is difficult and often associated with a high mortality and morbidity. The high mortality and morbidity are primarily related to anatomic features and techniques of cerebral protection employed during the period of aortic branch occlusion needed for reconstruction. This study reports our experience of 20 consecutive cases of acute type A aortic dissection treated by repair or replacement of the transverse aortic arch during emergency operation. Ages of the patients ranged from 56 to 76 years. All patients were referred to us within 2 weeks of onset (mean time, 58 hours). Selective cerebral perfusion or deep hypothermia with complete circulatory arrest was employed during the period of aortic branch occlusion. Duration of cerebral perfusion, circulatory arrest, myocardial ischemia, and cardiopulmonary bypass averaged 106 minutes, 32 minutes, 127 minutes, and 248 minutes, respectively. There were three operative deaths. All three dissections were ruptured ones, and the patients died of hemorrhage, deep coma, or multiple organ failure. One patient died of infection 3 months after operation. The remaining patients are alive and well without any detectable neurological deficit 1 month to 4 years postoperatively. This experience emphasizes that repair or replacement of acute type A aortic dissection involving the aortic arch can be performed safely by adequate selection of patients, supportive measures, and operative methods.

[Separate perfusion of upper and lower body for ruptured thoracoabdominal aortic aneurysm--a case report]

A case of ruptured thoracoabdominal aortic aneurysm was presented. The patient had emergent replacement of thoracoabdominal aorta with an aid of separate perfusion of upper and lower body. The postoperative course was uneventful. It was suggested that separate perfusion of upper and lower body was useful in the patients who require extensive aortic replacement and who are at substantial risk for spinal cord injury.

[A clinical study of the myocardial protective effect of allopurinol]

This study was proposed to study the myocardial protective effect of allopurinol clinically. This study involved 65 patients undergone coronary artery bypass operations or cardiac valve replacements or plasties. Patients were divided into two groups: group I, 30 patients received 2,400 mg of allopurinol preoperatively; group II, 35 patients undergoing no treatment of allopurinol. Postoperative values of GOT, CK-MB and LDH1 + LDH2 in group I were significantly lower than that of group II. These results suggest that allopurinol has advantageous effect on myocardial protection.

[Surgical experience in patients with Marfan's syndrome and cardiovascular disease]

10 patients with Marfan's syndrome and cardiovascular disease were operated at Tohoku University Hospital from 1971 to 1988. Surgery included composite valve graft replacement of ascending aortic aneurysm with aortic regurgitation in 5 patients and prosthetic mitral valve replacement in three patients; two had resection of aneurysm with Dacron tube replacement. Operative mortality was 10%. Two late death occurred (22%). It was suggested that regular follow-up examination is important in these patients to detect new lesions and to evaluate known lesion.