Evaluation of conventional circulatory assist devices. Intraaortic balloon pumping, venoarterial bypass, and extracorporeal membrane oxygenation.

This study was undertaken to reveal the limitations and problems with the conventional mechanical circulatory assist devices by analyzing the results in 70 cases; intraaortic balloon pumping (IABP group, n = 42), venoarterial bypass pumping (VAB group, n = 18), and extracorporeal membrane oxygenation (ECMO group, n = 10). The IABP could significantly prevent the development of postoperative low cardiac output state, and the best survival rate (62 percent) was obtained in the coronary arterial disease group. In the VAB group, eight (44 percent) cases were weaned, and four (22 percent) cases survived. These conventional assist devices could, though with limitations, certainly support the circulation and/or provide a period for it to recover, otherwise bridging the patients to new methods. The early decision not only for initiation of mechanical assist devices but also for moving to more definite procedures will improve the results with such devices.

Magnetic resonance evaluation of patency of stented polytetrafluoroethylene graft connecting right atrium to pulmonary artery.

Magnetic resonance imaging (MRI) was used to evaluate late postoperative patency of a stented polytetrafluoroethylene (PTFE) graft, which had been used to connect the right atrium to the pulmonary artery in a patient with tricuspid atresia. The MRI depicted patency, luminal size, course, and geometric morphology of the conduit.

Total correction of Ebstein's anomaly by replacement with a biological aortic valve without plication of the atrialized ventricle.

For the surgical management of Ebstein's anomaly, the preferred operation will be Hardy's procedure, which preserves the patient's valve. However, we have encountered 3 cases of this disease in which the downward displacement of the tricuspid valve was so severe and the functioning right ventricle was so small that Hardy's method could not be adapted without causing tricuspid regurgitation and making the right ventricular chamber more narrow. We treated these patients by replacing the tricuspid valve with an inverted aortic valve with a stent and not plicating the atrialized ventricle. The results have been proved satisfactory through about 7 years' follow-up, suggesting that our technique will be remarkably effective as a radical corrective operation for Ebstein's anomaly with severe intracardiac abnormalities.

Coarctation restenosis after isthmosubclavioplasty. A consideration on operative procedure and intraluminal balloon angioplasty.

We describe a case of a six-month-old boy in whom an aortic coarctation restenosis had developed three months after isthmosubclavioplasty. The restenosis was successfully relieved by means of intraluminal balloon angioplasty. At the isthmosubclavioplasty operation, extensive mobilization of the aorta to facilitate the anastomosis should be avoided. From anatomic and operative viewpoints, coarctation restenosis after the isthmosubclavioplasty operation was considered to be amenable to the intraluminal balloon angioplasty.

Development of a new experimental model for total exclusion of the right heart without the aid of cardiopulmonary bypass.

A new experimental model for the total exclusion of the right heart was successfully developed in mongrel dogs without the use of cardiopulmonary bypass. A Y-shaped conduit was constructed with tube grafts spirally stented on the exterior (10 mm in diameter), and each upper limb of the conduit was provided with a 30F cannula. The foot of the conduit was anastomosed with the main pulmonary artery in an end-to-side way with a side clamp. After a closed atrioseptostomy was performed with a special knife of our design, the upper limbs of the graft were connected to the superior and inferior venae cavae by a cannulation method. The operative procedure was completed by tightening the occluding snares around the venae cavae and ligating the root of the pulmonary artery and azygos vein. Thus, without any use of the right atrium, venous blood from the venae cavae was totally diverted to the pulmonary circulation via the conduit, and only the coronary venous return was shunted to the left atrium. Five consecutive dogs tolerated the operative procedure. No pressure gradients were observed between the pulmonary arteries and venae cavae. The circulation with this model was able to be sufficiently sustained with mean pulmonary arterial pressures of about 25 mm Hg, and no significant changes were shown in the left ventricular pump function from the preoperative state. However, the decrease in the mean pulmonary artery pressure to 20 mm Hg resulted in severe circulatory failure, and two of the five dogs succumbed to this condition. Our new model will be useful for studying the hemodynamic characteristics of the circulation after operations that result in total exclusion of the right heart.

Serial evaluation of cardiac function with aortic regurgitation caused by serious aortic lesions. A preliminary comparative study with isolated chronic aortic incompetence.

Clinical and hemodynamic appearances of aortic regurgitation caused by serious aortic lesions (AR-Ao-group) seemed more deteriorated than those with isolated chronic aortic regurgitation (AR-group). Often postoperative course and operative outcome are smooth and satisfactory in the AR-Ao-group. To support this observation, serial changes of left ventricular (LV) function and LV sphericity were evaluated before and after operation in ten cases in the AR-Ao-group and compared with those in the AR-group. Before operation, there were no significant differences in LV function between the two groups. Postoperative improvement of LV sphericity and LV function were statistically better in the AR-Ao-group. The LV function reserve was considered sufficiently retained in the AR-Ao-group. Results with this study supported that clinical observation. Therefore, the total correction, at the same time of aortic incompetence and aortic lesions is recommended.

Pulmonary artery connection in the Fontan procedure. Flexible polytetrafluoroethylene conduit for expansion.

From clinical experiences with the Fontan operation in six cases, a few practical contrivances and operative steps are described. We stress that meticulous care should be taken not to cause any stenotic complication in the outflow tract toward the pulmonary artery, particularly by traction of the right atrial appendage only to achieve a direct anastomosis. Conduit repair would be necessitated by cases in order to expand the indicative criteria vertically as well as horizontally. For conduit material, we used consecutively nonvalved polytetrafluoroethylene that was reinforced by handmade stainless steel wire ring (Gore-Tex, Inc) or by spirally built-in stent (IMPRA, Inc). The latter was eventually useful in obtaining natural curving of the conduit without kinking or compression. Some contrivances in anastomosing a conduit were also proposed to achieve an excellent result. We believe these practical contrivances will serve for expansion of the indicative criteria and promise improved operative outcome.

Oxygenated perfluorocarbon, recombinant human superoxide dismutase, and catalase ameliorate free radical induced myocardial injury during heart preservation and transplantation.

The effect of free radical scavengers on free radical-induced myocardial injury during heart preservation and transplantation was examined. Four groups of nine hearts each were harvested from mongrel dogs (12.5 to 16.5 kg) and orthotopically transplanted to size-matched recipients. All hearts received a continuous perfusion of oxygenated modified Collins' solution (group A). In addition, groups B, C, and D received Fluosol DA and albumin. Preservation perfusion was performed for 18 hours, at 4 degrees C, pH = 7.4, and 20 mm Hg. In group C, recombinant human superoxide dismutase (4,080 U/mg, 20 mg/kg) and bovine catalase (46,200 U/mg, 20 mg/kg) were administered only during preservation perfusion. In group D, these scavengers were administered just before and during reperfusion for 1 hour. Hemodynamic studies were performed before excision of the donor hearts and 1 hour after the termination of cardiopulmonary bypass. Creatinine kinase MB isoenzyme and thiobarbituric acid reactive substance levels in the coronary effluent were determined during preservation perfusion and reperfusion. Only group A showed a significant heart weight gain (p less than 0.05) and a decline in passive compliance (p less than 0.05) during preservation. Lactate release was higher in group A than in the groups receiving Fluosol DA. In contrast, pyruvate levels in group A were lower than in other groups. The generation of free radicals stayed at a low level during preservation, but significantly increased during reperfusion and was associated with a corresponding increase in creatinine kinase MB isoenzyme. Perfusion with a perfluorochemical solution (group B) inhibited the sharp rise in levels of thiobarbituric acid reactive substances and of creatinine kinase MB isoenzyme and improved cardiac function during reperfusion (versus group A). Exogeneous free radical scavengers administered just before and during reperfusion (group D) significantly ameliorated thiobarbituric acid reactive substances and creatinine kinase MB isoenzyme levels and also induced a significant hemodynamic improvement during reperfusion. However, administration of scavengers during preservation did not. This study demonstrates that the generation of free radicals is primarily significant during reperfusion and reoxygenation after ischemia. Thus the best time for administration of scavengers is just before and just after the onset of reperfusion. Furthermore, perfusion with perfluorochemicals effectively maintains aerobic metabolism and ameliorates free radical damage during this period.

Efficacy of intra-aortic balloon pumping for failing Fontan circulation.

The Fontan circulation occasionally cannot be sustained by currently available medical treatment. In these circumstances, mechanical assistance to the Fontan circulation should be considered. We have experienced three cases where Fontan circulation was assisted by intra-aortic balloon pumping (IABP). The hemodynamic improvement and weaning from IABP were successfully achieved in all cases. One patient survived the serious postoperative course with the aid of IAPB, and two patients died following multiorgan failure, though the circulation had eventually been re-established. By studying the postoperative hemodynamics assisted by IABP, it is concluded that IABP is a reasonable, efficacious strategy to support and to re-establish the failing Fontan circulation, though the changes in hemodynamic variables will not immediately coincide with IABP application.

Fistula formation from neovascularity developing in malignant fibrous histiocytoma of the heart.

Neovascularity in cardiac tumours is uncommon and fistula formation from such neovascularity is extremely rare. Fistula formation from neovascularity developing in a malignant fibrous histiocytoma of the heart is described in a 48-year-old man. The the case illustrates that cardiac tumour is not only a cause of cardiac output obstruction but also of coronary artery fistula.

Spontaneous secure reimplantation of a dislodged pacemaker electrode onto the right ventricular outflow tract, reestablishing a sufficient pacing condition.

A 62-year-old woman underwent cardiac pacemaker implantation for sick sinus syndrome with bradycardia, and the tip of an endocardial tined lead was positioned to the right ventricular apex. On the fifth postoperative day, an incomplete pacing failure, lasting about 10 min, was observed transiently on 24-h monitoring. This event, however, was not considered to be a clinical manifestation of the ensuing complication until the patient visited our pacemaker clinic 2 months postoperatively. At that time, a chest x-ray demonstrated that the electrode tip had migrated markedly to the right ventricular outflow tract (RVOT), but presented a sufficient pacing condition. The reimplantation site appeared to be very insecure for pacing, raising the potential risk of repeat dislodgement since the lead was not provided with a helix. At the second operation, performed to assess the problem, the ventricular excitation threshold measured at 1.3 V with a 0.5 ms pulse width. Furthermore, it was unexpectedly disclosed that the electrode tip was so tightly anchored at the site that it could not be withdrawn, eliminating the possibility of repeat dislodgment. Consequently, the entire original pacing system could be used as before and no further complications were observed. Although the situation encountered was very rare and seemed to be problematic, careful observation might be an alternative to surgical intervention even when a tined tip without helix has been used.

Expanded selection criterion for Fontan's operation based on the size of distal pulmonary arteries.

This study examined pulmonary arterial size to clarify a quantitative selection criterion for Fontan's operation in six cases without pulmonary hypertension. Pulmonary arterial size was angiographically assessed before and after the operation. No enlargement of the artery was observed, even after the procedure, confirming the importance of preoperative pulmonary arterial size. All three cases with preoperative PAa/N-RPAa of more than 0.5 survived the operation, whereas two of the remaining three cases (less than 0.5) died due to low cardiac output. The only survivor in the latter group had previously received Glenn's anastomosis. Hemodynamic study was done simultaneously, and a significant exponential correlation was obtained between preoperative PAa/N-RPAa and perioperative post-repair right atrial pressure (p less than 0.025). It was concluded that the selection criterion based on pulmonary arterial size could be expanded to a PAa/N-RPAa value of 0.5 when no Glenn's anastomosis had previously been done and the rudimentary right ventricle was not to be utilized. The exponential curve is useful for postoperative care in Fontan's operation, since it indicates the central venous pressure necessary to sustain the circulation at a level corresponding to the preoperative pulmonary arterial size.

Surgical correction of Ebstein's anomaly by tricuspid valve replacement and its late problems.

The choice between valve replacement and plasty for surgical management of Ebstein's anomaly still remains controversial. Since 1960, we have treated 16 cases of Ebstein's anomaly, and 7 of the 16 cases have undergone surgical correction. Tricuspid valve replacement (TVR) without plication of the atrialized ventricle was applied in 4 cases, and Hardy's procedure was adopted in three cases. The division of the Bundle of Kent was carried out simultaneously in 2 cases with Wolff-Parkinson-White (W-P-W) syndrome of the TVR group. All patients have survived the operation. Early and late (as long as 14 years) postoperative evaluations have demonstrated superiority of the TVR group. However, the late echocardiographic findings have revealed new problems in the TVR group, such as hypokinetic or paradoxical motion of the atrialized ventricle in two cases and hypofunction of the left as well as the right heart.

Echocardiographic prediction of postoperative low cardiac output syndrome in patients with mitral stenosis.

Thirty-eight patients were operated on for mitral stenosis between March 1979 and September 1981. Thirty-six of them were examined as to their age, symptom duration, chest roentgenograms, electrocardiograms and echocardiograms to obtain various indices of left ventricular function. The usefulness of these indices as preoperative risk factors for predicting postoperative low cardiac output syndrome (LOS) was investigated. Cases which had values of ejection fraction, cardiac index, percent fiber shortening or mean velocity of circumferential fiber shortening less than 0.45, 2.0 l/min/m2, 25% and 0.80 circ/sec, respectively, in the preoperative echocardiographic examination were associated with a greater chance of postoperative LOS. Each of these factors was independently useful as a risk factor in cardiac surgery for mitral stenosis. Moreover, it was revealed that the combination of a preoperative percent fractional shortening (%FS) of less than 30% and a cardiac index smaller than 2.0 l/min/m2 indicated a strong predisposition toward postoperative LOS.

Evaluation of the left ventricular reserve by dynamic exercise echocardiography after surgery for valvular heart diseases.

Dynamic ergometer exercise in a supine position was applied to 64 patients more than 1 year after valvular heart surgery, and the left ventricular reserve was evaluated echocardiographically. The left ventricular reserve declined in the mitral stenosis-mitral valve replacement group, while it was better maintained in the mitral stenosis-mitral commissurotomy, aortic regurgitation and aortic stenosis groups. The patients were divided into 3 groups depending on whether the percentage increase during exercise of stroke index, an index of left ventricular pump function, increased, unchanged, or decreased. The percentage increase of mean velocity of circumferential fibre shortening (y) and that of left ventricular end-diastolic diameter (x) during exercise were plotted for each group. The increased group was isolated from the unchanged group by the line of y = -5.02x + 30.1; the unchanged group was isolated from the decreased group by that of y = -5.68x-10.0, and the increased and unchanged groups were clearly isolated from the decreased group by that of y = -6.86x-4.76. We conclude that dynamic ergometer exercise echocardiography is useful for evaluating the left ventricular reserve of postoperative patients with valvular heart disease. It was also thought that the subclinical state of cardiac failure can be effectively detected by the present method.

Intrathecal oxygen concentration as a new indicator of spinal cord ischemia.

A number of approaches have been put forward to monitor spinal cord ischemia during thoracic and thoracoabdominal aortic occlusion. However, none of these can ultimately prevent devastating complications which result from ischemic spinal cord injury. A direct measurement of the oxygen content of the spinal cord may accurately indicate the perfusion state, but in practice it is impractical. We surmised that intrathecal and/ or epidural oxygen concentration(I-pO2 and E-pO2, respectively) accurately reflect oxygen content in the spinal cord. So, we examined whether or not I-pO2 and/or E-pO2 correlated with the spinal cord pO2 (S-pO2) in dogs. In nine mongrel dogs, a model of graded spinal cord ischemia was developed by stepwise alternation of the level of aortic occlusion with an intraaortic balloon catheter. I-pO2, E-pO2 and S-pO2 were measured with a mass spectrometer. Our results show that, both I-pO2 and E-pO2 significantly correlated with S-pO2. I-pO2 correlated with S-pO2 better than E-pO2 did. Therefore, I-pO2 can be used as a new indicator for spinal cord ischemia, and I-pO2 monitoring would be useful to prevent paraplegia associated with thoracic aortic surgery.

Post-Fontan care based on hemodynamic characteristics, with special reference to the central venous pressure.

Changes in the hemodynamics of six patients having received Fontan-like operations were closely observed during the first 48 h after the operation. Catheterization studies and simultaneous angiocardiography were also performed before and after the operation. Hemodynamic derangement was particularly severe during the first 24 h postoperatively as indicated by a low cardiac output of less than 2.01/min/m2, which persisted in spite of very high central venous pressure. Furthermore, the central venous pressure needed to re-establish the circulation soon after the Fontan procedure significantly correlated with the angiocardiographically assessed preoperative size of distal pulmonary arteries. Accordingly, the preoperative evaluation of the distal pulmonary arterial size is very important, that provides a good guide-line for the degree of circulatory volume expansion necessary to elevate the central venous pressure and to sustain the circulation in the early postoperative period.

Angiocardiographic quantitative evaluation of double-outlet right ventricle: special reference to the morphology of the common outflow tract.

Geometrical measurements of angiocardiograms of the common outflow tract (COT) of 13 patients were made to determine in which cases internal conduit repair was feasible, and under which conditions a patch enlargement of the COT was indicated. In the pulmonary stenosis (PS) group, the area of the narrowest cross-section of the COT was significantly smaller than that in the pulmonary hypertension (PH) group (p less than 0.025). In the PS group, the area was rarely sufficient to be shared by systemic and pulmonary circulation. Therefore, stenosis in the outflow tract to the pulmonary artery will occur if the intraventricular tunnel technique is applied, without patch enlargement of this portion, to patients with PS. On the contrary, the cross-sectional areas of the COT and pulmonary arteries were significantly larger in the PH group than in the PS group. Accordingly, the intracardiac conduit operation may be possible in such patients without a patch enlargement, even in young patients if other intracardiac conditions allow. Preoperative angiocardiographic evaluation of the COT is helpful in preoperatively selecting the proper operative procedure for this anomaly.

Efficacy of percutaneous transluminal coronary recannalization for preservation of the post-infarct left ventricular regional wall motion: a trial of the evaluation by weighting coronary artery segments.

Efficacy of the percutaneous transluminal coronary recannalization (PTCR) therapy was evaluated by weighting infarct-related coronary artery segments in 28 consecutive patients with acute myocardial infarction. The study focused on the influences of the time interval from the onset of chest pain to PTCR (PTCR-Time) and on the post-infarct left ventricular regional wall motion in conjunction with the serum levels of GOT, LDH and CPK and with PTCR-Time. PTCR success rate was 84.0%, and re-occlusion rate was 4.0%. The thrombolysis in myocardial infarction grade 2, however, was observed in 7 (33.3%) of 21 cases with successful PTCR. There was no significant difference in PTCR-Time between the PTCR success and nonsuccess groups. Significant correlations were observed between the PTCR-Time and each peak value of standardized serum levels of LDH and CPK, and between the PTCR-Time and the post-infarct regional wall motion abnormality. There were also significant correlations between the standardized serum level of each of these three enzymes and the post-infarct regional wall motion abnormality. It was clearly demonstrated that the earlier the recannalization of the infarcted artery was achieved, the less extensive the myocardial damage in quantitative and qualitative aspects.

Continuous measurement of tissue oxygen and carbon dioxide gas tensions in dog liver in ischemia/reperfusion.

An experiment was conducted to determine whether the oxygen and carbon dioxide gas tensions in liver tissue (PtO2 and PtCO2, respectively) reflect the state of microcirculation and/or metabolism in the ischemic liver. Subjects were divided into three groups: group 1, 30 min ischemia; group 2, 60 min ischemia; group 3, four times of intermittent 15 min ischemia after every 10 min of reperfusion. PtO2, PtCO2 and tissue blood flow (TBF) were measured by mass spectrometry, comparatively studied with the serum GOT level as an indicator of liver tissue damage. Furthermore, the time point at which the PtCO2 increase for 1 min initially became less than 1/2 of the maximum value was located on the transit curve of PtCO2, referred to as the critically anaerobic (CA) point, with which new indices of critically anaerobic score (CAS) and time (CAT) (see details in text) were developed. The profiles of PtO2 and PtCO2 during ischemia and reperfusion were clearly demonstrated, and the CA point was observed 12.7 +/- 2.9 min after induction of ischemia. PtO2 was positively correlated with TBF and negatively with the serum GOT level. Furthermore, not only CAS but also CAT were significantly correlated with PtO2, TBF, and the serum GOT level. It was concluded that PtCO2 reflects the state of anaerobic tissue metabolism during ischemia and PtO2 reflects the magnitude of microcirculatory disturbance and tissue injury caused by ischemia/reperfusion. Therefore, continuous monitoring of not only PtO2 but also PtCO2 is beneficial for patients undergoing hepatic surgery with ischemia.