Two cases of single-stage lip and nostril reconstruction in holoprosencephaly.

Holoprosencephaly is a rare disorder of embryological development that presents with midline clefting of the lip. The incidence has been estimated at approximately 1 in 15,000. Previously, infants with severe holoprosencephaly were thought to die within 1-2 years of birth and seldom to benefit from surgery. Survival has increased with improved perinatal care and support services. Parents often request complete cheiloplasty, because the presence of a columella greatly influences aesthetic outcome. The authors report two cases of simultaneous columella reconstruction with cheiloplasty.

Observation and quantification of cavitation on a mechanical heart valve with an electro-hydraulic total artificial heart.

In previous studies, we investigated the cavitation phenomenon in a mechanical heart valve using an electro-hydraulic total artificial heart. With this system, a 50% glycerin solution kept at 37 degrees C was used as the working fluid. We reported that most of the cavitation bubbles were observed near the valve stop and were caused by the squeeze flow. However, in these studies, the effect of the partial pressure of CO(2) on the mechanical heart valve cavitation was neglected. In this study, in order to investigate the effect of the partial pressure of CO(2) on mechanical heart valve cavitation using an electro-hydraulic total artificial heart, we controlled the partial pressure of the CO(2) in vitro. A 25-mm Medtronic Hall valve was installed in the mitral position of an electro-hydraulic total artificial heart. In order to quantify the mechanical heart valve cavitation, we used a high-speed camera. Even though cavitation intensity slightly increased with increases in the PCO(2) at heart rates of 60, 70 and 100 bpm, throughout the experiment, there was no significant difference between the PCO(2) and cavitation intensity.

A metastatic haemangiopericytoma of the floor of the mouth.

A case of metastatic haemangiopericytoma in the floor of the mouth is described. Haemangiopericytoma is a relatively rare slow-growing vascular tumour with variable malignant potential. This tumour has been identified in almost every region of the body, but its occurrence in the oral cavity has been rarely reported. The rate of regional and distant metastasis of the tumour is low. This case, presented 12 years after initial surgery suggested the need for careful long-term follow-ups of patients with haemangiopericytoma.

Cavitation phenomenon in monoleaflet mechanical heart valves with electrohydraulic total artificial heart.

Recently, cavitation on the surface of mechanical heart valves has been studied as a cause of fractures occurring in implanted mechanical heart valves. In this study, to investigate the mechanism of cavitation bubbles associated with monoleaflet mitral valves in an electrohydraulic total artificial heart (EHTAH), and to select the best valves for our EHTAH system, we measured three parameters. First, an image was created of the cavitation bubbles using a high-speed camera. Second, pressure drop in the vicinity of the valve surface was measured using mini pressure sensor. Then, the closing of the valve was observed using a Laser displacement sensor. Most of the cavitation bubbles in the Medtronic Hall valve were observed at the edge of the valve stop. With the Omnicarbon valve, the cavitation bubbles were observed at the edge of the valve and on the inner side of the leaflet. On the other hand, cavitation bubbles were observed only on the inner side of the leaflet in Björk-Shiley valve. Cavitation bubbles concentrated on the edge of the valve stop; the major cause of these cavitation bubbles was determined to be the squeeze flow. The formation of cavitation bubbles depended on the valve closing velocity and the valve leaflet geometry. From a viewpoint of squeeze flow, a low closing velocity and a small size of the valve stop could minimize cavitation.

Prostaglandin synthesis inhibitor improves hypotension during normothermic cardiopulmonary bypass.

Hypotension is a major systemic side effect during cardiopu monary bypass (CPB), especially at normothermia. We previously reported that prostaglandin (PG) might play a substantial role in hypotension. The purpose of this study was to clarify whether a PG synthesis inhibitor (PGSI) could improve hypotension during CPB. Thirty-six patients undergoing cardiac surgery with normothermic CPB (35-37 degrees C) were divided into two groups: a PGSI group (n = 18), whose members wer given a PGSI before and during CPB, and a control group (n = 18). In both groups, perfusion flow was sufficient and pressure was maintained at above 45 mm Hg by infusion of metaraminol, a vasoconstrictor. The mean arterial pressure throughout CPB was significantly higher in the PGSI group than in the control group (57 +/- 4 vs. 48 +/- 3 mm Hg, p < 0.01), whereas the dose of infused metaraminol was significantly lower in the PGSI group (13 +/- 7 vs. 21 +/- 6 mg, p < 0.01). The blood base excess was not significantly different (1.0 +/- 1.6 vs. 1.7 +/- 1.9 mmol/L, p = 0.28), and urine output was significantly higher in the PGSI group (503 +/- 179 vs. 354 +/- 112 ml/hr, p < 0.01). In conclusion, PGSI can improve hypotension during CPB and increase urine output without impairing peripheral circulation.

Application of indirect flow rate measurement using motor driving signals to a centrifugal blood pump with an integrated motor.

The method of measuring the flow rate of a centrifugal blood pump from the input electric power, which will be indispensable for the long-term use of such devices, was developed and was applied to the direct-driven centrifugal blood pump that has been developed by our research group. The accuracy was evaluated in a chronic animal experiment using an adult goat. The results demonstrated that this method carries the sufficient potential of the instantaneous monitoring method, but errors due to electromagnetic and mechanical losses were not determined always precisely. The detection of adverse phenomena such as the obstruction of the inlet cannula was also possible from the estimated value of the flow rate and its waveform pattern.

Performance of a newly developed implantable centrifugal blood pump.

The performance of the newly developed implantable centrifugal blood pump was investigated in vitro. The pump was developed with the end goal of building a versatile system that includes a left ventricular assist system with an internal secondary battery or an implantable biventricular assist system with two implantable blood pumps. The hydrodynamic characteristics and efficiency of the blood pump were evaluated, and the mechanical damage to the blood caused by the blood pump was assessed through a hemolysis test using fresh goat blood. The pump could generate 120 mm Hg at a flow rate of 5 L/min and a motor speed of 2,500 rpm. The electric input power to the pump was approximately 5 watts under these working conditions. The hemolysis caused by the pump was a bit higher than that by the former model, but stayed within an acceptable range. Performance of the pump in vitro was considered sufficient for a left ventricular assist device, although further design improvement is necessary in terms of hemolysis and system efficiency to improve biocompatibility of the pump.

Change in vasoconstrictive function during prolonged nonpulsatile left heart bypass.

We investigated changes in vasoconstrictive function accompanying prolonged nonpulsatile left heart bypass (NLHB). After 2-week pulsatile left heart bypass (PLHB) in 11 goats, NLHB was conducted for another 4 weeks (Group N) in 6 goats. In the other 5 goats, PLHB was continued for another 4 weeks (Group P). Systemic vascular resistance at rest (rSVR) was measured on the last days of the second and sixth postoperative week (W2 and W6, respectively). Subsequently, phenylephrine was injected, and the maximum values (SVRmax) and the maximum increasing change in SVR (DeltaSVR) were measured. No significant difference was observed in rSVR between groups at W2 or W6. The SVRmax and the DeltaSVR at W2 were consistent in both groups. However, at W6, the SVRmax and the DeltaSVR of Group N were significantly lower than those of Group P. In conclusion, prolonged NLHB caused a significant decrease in the SVR response to phenylephrine, indicating a dimunition of vasoconstrictive function.

Oxygen metabolism under various bypass flow conditions during cardiopulmonary support in awake goats.

Despite its wide clinical application, patient recovery from cardiopulmonary support (CPS) is not necessarily satisfactory. To clarify what influence CPS has on organ perfusion, we investigated the oxygen metabolism under various bypass flow (BF) conditions in a series of chronic animal CPS experiments. The CPS system, which consists of a pulsatile ventricular assist device and a compact artificial lung was installed without anesthesia in 6 adult goats weighing 49-51 kg. BF was adjusted stepwise from 0% to 50%, 75%, 90%, and 100% of total systemic blood flow (TSF) by balancing the pulmonary arterial flow. The animals' TSF and oxygen delivery (DO2) were sufficiently maintained throughout the experiments. The oxygen consumption (VO2) and the oxygen extraction rate (ExO2) increased from 178+/-14 to 342+/-19 ml/min, and from 28+/-2% to 64+/-1%, respectively, in proportion to the increase of CPBF dependency from 0% to 100%. The blood lactate level did not change appreciably even at 90% BF from 5.7+/-0.3 to 11.2+/-1.2 mg/dl, but drastically elevated to 23.5+/-4.6 mg/dl at the total bypass. This indicates that CPS leads to a relative lack of oxygen and can induce organ dysfunction due to increasing VO2 and ExO2 in proportion to the increase of BF dependence even if TSF and DO2 are sufficiently maintained.

Mixed venous oxygen saturation as a promising parameter for physiologic control of total artificial heart.

Mixed venous oxygen saturation (SvO2) has been proposed as one of the suitable parameters for physiologic control of a total artificial heart (TAH). To establish the practical application of SvO2, we investigated the response of cardiac output (CO) and SvO2 to step-loaded exercise. A normal calf was surgically equipped with an ultrasonic flowmeter probe and an oximetry catheter in the pulmonary artery to measure CO and SvO2, respectively. Three stage step treadmill exercise tests (1, 2, and 4 km/h) were performed three times. While CO increased from 8.9 L/min at preexercise level to 9.7, 10.2 and 11.4 L/min at 1, 2, and 4 km/h, respectively, SvO2 decreased from 59.6% to 56.8, 55.3, and 52.2%, respectively. There existed a linear correlation between the magnitude of changes in CO and SvO2. CO and SvO2 exhibited a similar course of change, expressing an inverted exponential curve. The time constant of SvO2 was from 19 to 35 seconds, whereas that of CO was from 21 to 39 seconds. We conclude that SvO2 changes in close association with CO during exercise and has good potential to be a parameter for physiologic control of a TAH, by reflecting the recipient's CO demand without conspicuous time delay.

Influence of pulsatile and nonpulsatile left heart bypass on the hormonal circadian rhythm.

We investigated endocrine circadian rhythm (CR) during pulsatile and nonpulsatile left heart bypass (PLHB and NLHB). A ventricular assist device (VAD) was installed in five goats. After 2 weeks of PLHB, NLHB was subsequently conducted for 4 weeks. The levels of melatonin, cortisol, and renin activity were measured every 2 hours for 24 hours on the last day of the second PLHB week and the second and fourth NLHB weeks. Acquired data were compared with those of the normal control goats (Cont) to determine the presence or absence of CR, as well as the timing, acrophase, amplitude, and mesor of CR. Variations in melatonin, CR were consistently detected at all sampling points. In contrast, CR of cortisol during PLHB and NLHB was observed in a few cases, although considerable CR was noted in most of the Cont cases. The variations in renin activity indicated CR in most of the Cont cases and in all cases at all sampling points during PLHB and NLHB, whereas their acrophases were diversified. In conclusion, the CR of melatonin, reflecting the fundamental circadian clock, was maintained during both PLHB and NLHB, while it could be modified for stress sensitive cortisol and hemodynamic responsive renin during these bypass modalities.

Noninvasive assessment method to determine the anatomic compatibility of an implantable artificial heart system.

To assess the anatomic compatibility of an artificial heart (AH), we attempted to develop a computer environment that would facilitate a reliable simulation of an AH implanted in the human thorax. A three-dimensional thoracic computer model with a ventricle-resected heart was constructed, by using manually extracted contour points of the aorta, pulmonary artery, atria, atrioventricular valves, diaphragm, and thoracic wall from a set of consecutive CT images. Such a model enabled simulation of an AH implantation by orienting the AH model in it. Error evaluation on CT imaging and contour extraction with a Plexiglas cylindrical phantom showed that the diameter of the extracted phantom contour was approximately 2 mm smaller than its original with a standard deviation of <0.5 mm. Errors in contour and surface reconstruction could be reduced to far less than 1 mm under constrained conditions. A study on the influence of breathing revealed that variations in some thoracic dimensions between inspiration and expiration could reach 10 mm. In summary, computer simulation of AH implantation is a worthwhile approach with acceptable accuracy, although further considerations of extreme thoracic situations will be required.

Computational fluid dynamics analysis of a centrifugal blood pump with washout holes.

The authors studied avoidance of coagulation occurrence using computational fluid dynamics (CFD) analysis from the fluid dynamical point of view. Concerning centrifugal pumps, blood coagulation sometimes occurs at the region behind the impeller where the flow is generally stagnant. Therefore, we conducted a thorough study with the specimen pump with and without washout holes, mocking up the Nikkiso HPM-15. As the result, the model with washout holes indicated that the fluid rotates rapidly at the vicinity of the shaft and generates washout effects near the stationary rear casing. On the other hand, the model without washout holes showed that fluid cannot be quickly shipped out of the area behind the impeller and rotates mildly around the shaft. To clarify the moving relations between the impeller and the fluid, validation studies by comparing the results of CFD analysis and flow visualization experiments are ongoing; thus far, the studies show that CFD results are similar to the results from flow visualization experiments.

Effects of reduced pulse pressure to the cerebral metabolism during prolonged nonpulsatile left heart bypass.

We investigated changes in the cerebral metabolism with long-term reduced pulse pressure. Nine goats underwent pulsatile left heart bypass (LHB) for 2 weeks while awake, and nonpulsatile LHB was subsequently conducted for 4 weeks. The average pulse pressure during nonpulsatile LHB (13, 10, 11, and 11 mm Hg at the 1st, 2nd, 3rd, and 4th nonpulsatile LHB week, respectively) was significantly lower than that during pulsatile LHB (36 mm Hg). There were no significant differences in either arterio-jugular venous oxygen differences (AJDO2) and cerebral oxygen extraction ratio between the 2nd pulsatile LHB week and the 1st, 2nd, 3rd, and 4th nonpulsatile LHB weeks. The arterio-jugular venous glucose differences, jugular venous-arterial lactate differences (JAD Lactate), and lactate oxygen indexes (JAD Lactate/AJDO2) also remained unchanged during the entire course of the experiments. In conclusion, the cerebral metabolism during nonpulsatile LHB did not change compared to that during pulsatile LHB.

Preprimed artificial lung for emergency use.

We investigated the possibility of preprimed storage of an artificial lung (AL), aiming at facilitating its emergency use. Test ALs, consisting of a special microporous hollow fiber membrane made of polyolefin in which direct blood-gas contact was completely eliminated, were preprimed with saline solution, sterilized by gamma-ray irradiation, and evaluated after 1-3 months of storage at room temperature. A small amount of bubble was noted in the priming solution after storage in some ALs, which most likely originated from the air dissolved in the priming solution or persisted in the liquid compartment at priming. Although the preprimed solution contained several polyolefin-breakdown products due to irradiation, including ethyl alcohol, n- and t-butyl alcohol, acetone, and carbon dioxide, the levels of these substances were at concentrations known to be not toxic. Endotoxin concentration was negligible. In SEM observation, no perceptible microstructural change was observed in the hollow fibers after preprimed storage. Maximum tensile stress and ultimate elongation of the hollow fiber in the test ALs were reduced by approximately 20% and 3%, respectively, from those of the control AL. The influence of preprimed storage on gas-exchange function was examined in a venoarterial bypass animal study using a goat. Oxygen transfer function was well preserved whereas carbon dioxide removal function was slightly lowered according to the storage term in the stored ALs compared with those of a nonpreprimed control AL. On the basis of these results, we conclude that preprimed storage of the AL with gamma-ray sterilization is basically feasible and realistic.

Prolonged nonpulsatile left heart bypass diminishes vascular contractility.

We investigated possible functional changes in the vascular system accompanying the morphological change in prolonged nonpulsatile left heart bypass (LHB). Three adult goats underwent pulsatile LHB. Two weeks postoperatively, the pulsatile ventricular assist device was replaced with a centrifugal pump and nonpulsatile LHB was subsequently conducted for 4 weeks. The mean aortic pulse pressure was 39 and 16 mmHg during the pulsatile and nonpulsatile LHB, respectively Systemic vascular resistance (SVR) and plasma norepinephrine levels were measured at the end of pulsatile LHB (PUL), and at the end of 1st, 2nd, 3rd, and 4th week of nonpulsatile LHB (NP1w, NP2w, NP3w, NP4w, respectively). At each point, 50 microg/kg nitroglycerin and 1 microg/kg norepinephrine were injected and the minimal and maximal values of SVR after injection were calculated as parameters reflecting the vascular tonus and contractility. The SVR and plasma nor epinephrine level did not significantly change during the entire course (SVR: 1106, 895, 982, 920, and 938 dyne x sec x cm(-5); norepinephrine level: 0.3, 0.2, 0.1, 0.2, and 0.1 ng/ml; at PUL, NP1w, NP2w, NP3w, and NP4w, respectively). The minimal value of SVR after nitroglycerin injection remained unchanged, indicating that vascular tonus was stable during the entire course (618, 687, 623, 560, 653 dyne x sec x cm(-5), respectively). In contrast, the maximal value of SVR after norepinephrine injection at NP3w and NP4w (1695 and 1759 dyne x sec x cm(-5)) became significantly reduced compared to that at PUL (2346 dyne x sec x cm(-5)). These results indicated that prolonged nonpulsatile left heart bypass did not affect the vascular tonus, but significantly diminished the vascular contractility.

Effects of long-term nonpulsatile left heart bypass on the mechanical properties of the aortic wall.

We investigated the mechanical properties of the descending aortic wall relative to its structural change caused by reduced pulse pressure in long-term nonpulsatile left heart bypass (LHB). Fifteen adult goats (53-68 kg) were divided into three groups: five goats underwent LHB with a nonpulsatile pump for 31 to 381 days (Group N), five goats underwent LHB with a pulsatile pump for 24 to 130 days (Group P), and the other five goats were used as normal control animals (Group C). The aortic pulse wave pressure was 17+/-7 mm Hg in Group N, 43+/-1 mm Hg in Group P, and 39+/-2 mm Hg in Group C. Structural changes were evaluated using wall thickness and the volume ratio of elastin and collagen. The mechanical properties were evaluated using "beta," which was calculated according to the equation: = (In P/Ps)/(Do/Ds-1), where Ps was the standard pressure, Ds was the wall diameter at pressure Ps, and Do was the wall diameter at pressure P. The wall thickness of the aortic wall in Group N (1.6+/-0.3 mm) was significantly thinner than that in either Group P (2.2+/-0.3 mm) or Group C (2.1+/-0.2 mm). The volume ratio of elastin in Group N (51 +/- 3%) was higher than that in Group P (44+/-1%) or Group C (40+/-1%), whereas no significant difference was found in the volume ratio of collagen between those in Group N (10+/-1%), Group P (9+/-2%), and Group C (10+/-1%). The stiffness parameter, beta, in Group N (3.1+/-0.7) was slightly higher than that seen in Group P (2.9+/-0.4) or Group C (2.9+/-0.2), but there was no significant difference between the three groups. These results indicate that long-term nonpulsatile LHB caused marked structural changes in the aortic wall, whereas the change in mechanical properties were not significant with regard to stiffness.

A transcutaneous energy transmission system with rechargeable internal back-up battery for a totally implantable total artificial heart.

We have been developing an externally coupled transcutaneous energy transmission system (ECTETS) for a totally implantable total artificial heart (TITAH). When the ECTETS is unable to supply the energy to drive the TITAH from outside the body, a rechargeable internal back-up battery (RIBB) implanted inside the body is used as a back-up to supply the required energy. This paper reports on the performance characteristics of our ECTETS with an RIBB. In this study, a lithium-ion (Li+) secondary battery was used as the RIBB. The transcutaneous energy transmission and the charging control characteristics of the ECTETS, while simultaneously supplying energy to the TITAH and the RIBB, were evaluated in an in vitro experiment. The output power and transmission efficiency of the ECTETS operating in this mode were found to vary from 20 W to 34 W and from 84% to 71%, respectively. It was also found that a sufficient power of more than 20 W could be supplied to the TITAH. The time needed to fully charge the RIBB was 117 minutes, and a fully charged RIBB could drive the TITAH, consuming 20 W for 62 minutes. It may, therefore, reasonably be concluded that the ECTETS with the RIBB is sufficient to drive the TITAH.

Progress of an electrohydraulic total artificial heart system with a separate energy converter.

We have been developing an electrohydraulic total artificial heart (EHTAH) system. The system consists of diaphragm blood pumps, an abdominally placed energy converter, an internal controller, a transcutaneous energy transfer (TET) system, a transcutaneous optical information transfer system, and internal and external lithium-ion (Li-ion) batteries. The energy converter was optimized to obtain better oil transfer. Maximum cardiac output and efficiency of the EHTAH were increased from 8 L/min to 10 L/min and from 10% to 12%, respectively. The volume of the energy converter was reduced from 280 to 210 ml. The pumping unit was successfully implanted in 68-85 kg calves without anatomic problems, and the calves survived up to 10 days with good circulatory results. The maximum temperature rise of the implanted energy converter was only 1 degrees C. Stable performance of the TET system was confirmed in goats for more than 1 month. DC-DC energy transfer efficiency with 20 W of energy transmission remained within the range of 80% to 85%, and no significant temperature rise was observed in the implanted circuit. The internal Li-ion battery was also evaluated in a goat, and the maximum temperature rise during the charging period was 1.5 degrees C, while the charging and discharging times were 72 and 58 min, respectively. We conclude that our system has progressed in its development as a practical implantable system.

Control of a total artificial heart using mixed venous oxygen saturation.

We developed a control of the total artificial heart (TAH) using mixed venous oxygen saturation (SvO2). With this method, the TAH output was controlled by automatically adjusting drive parameters in response to changes in measured SvO2. The feasibility and validity of this method were evaluated in a series of treadmill exercise tests using a calf implanted with a pneumatic TAH. The cardiac output (CO) and SvO2 were measured with an ultrasonic flowmeter and an oximetric catheter, respectively. The calf performed graded exercise under a fixed drive control mode (fixed mode), in which the drive parameters were unchanged throughout the treadmill test, and under the SvO2 based control mode (SvO2 mode). The calf could go to Stage 6 in both modes, but the maximal oxygen consumption in the SvO2 mode was 1.5 times as large as that of the fixed mode. Compared with the fixed mode, CO was increased effectively in the SvO2 mode, and the capacity for exercise was augmented. When considering the relationship between oxygen consumption and oxygen delivery, it was revealed that the CO in the SvO2 mode responded more adequately to the recipient's oxygen demand than that in the fixed mode. We conclude that this SvO2 based control method is feasible and physiologically effective.