[Is emergency aortic root replacement combined with arch replacement safe?].

BACKGROUND: Aortic root replacement (ARR) combined with aortic arch replacement (AAR) is an invasive procedure even in elective cases. Nevertheless, such combined operations are often mandatory in acute type A aortic dissection. We examined whether emergency operation might have further incremental risks compared with elective surgery in this type of operations. METHODS: Forty-six cases of ARR combined with AAR were divided into 2 groups, the emergency (EM) group and the elective (EL) group. The EM group consisted of 10 cases of acute type A aortic dissection, whereas the EL group of 36:23 of chronic aortic dissection and 13 of true aneurysm. RESULTS: There were no statistical differences between the 2 groups in the durations of aortic crossclamp, selective cerebral perfusion and cardiopulmonary bypass. The incidences in the EM and EL groups were as follows:in-hospital death; 0 vs 3( 8%), respiratory failure; 4 (40%) vs 14 (39%), renal failure; 0 vs 6 (17%), IABP requirement; 1 (10%) vs 3 (8%), and cerebral infarction; 0 vs 1 (3%), respectively. CONCLUSION: Early surgical results of emergency ARR combined with AAR were almost equal to those in elective surgery.

Photofragmentation of the K-shell excited perfluorocyclobutane: anisotropies in the fragments and breakdown pathways.

Total ion yield spectrum of perfluorocyclobutane (c-C(4)F(8)) has been measured in the C and F K-shell excitation regions. The peak assignments are presented based on angle-resolved photofragment ion mass spectrometry. The peaks at 291.34 and 688.5 eV are found to come from the transitions from the C 1s and the F 1s to the lowest unoccupied b(2)σ(CF)* orbital, respectively. A photoelectron-photoion-photoion coincidence spectrum is acquired at 700.1 eV for clarifying the breakdown pathways of c-C(4)F(8)(2+). Two series of the pathways are identified; fission of F atom(s) followed by charge separation and elimination of CF(2) or CF(3) followed by charge separation.

Photodissociation investigation of doubly charged ethanol clusters induced by inner-shell electron ionization.

Fragmentation of doubly charged ethanol clusters [(C(2)H(5)OH)(n)] following the O 1s ionization has been investigated by means of the photoelectron-photoion-photoion coincidence (PEPIPICO) method. The dominant fission channel of (C(2)H(5)OH)(n)(2+) was the formation of protonated cluster ion pairs [H(C(2)H(5)OH)(l)(+)/H(C(2)H(5)OH)(m)(+)]. The fragmentation mechanisms of these ion pairs were discussed based on the analysis of the PEPIPICO contour shape. It was clarified that the prominent fragmentation channel was a secondary decay mechanism, where neutral evaporation occurs after charge separation. On the other hand, the formation of small fragment ions was suppressed, excluding the formation of certain specific fragments (H(3)O(+), C(2)H(5)(+)/COH(+), and C(2)H(4)OH(+)). The formation of small fragment ions was suppressed due to the cooling effect caused by the neutral evaporation and the decrease in the electrostatic repulsive force caused by charge separation.

Assessment of synchronization measures for effective ventricular support by using the shape memory alloy fibred artificial myocardium in goats.

Thromboembolic and haemorrhagic complications are the primary causes of mortality and morbidity in patients with artificial hearts, which are known to be induced by the interactions between blood flow and artificial material surfaces. The authors have been developing a new mechanical artificial myocardial assist device by using a sophisticated shape memory alloy fibre in order to achieve the mechanical cardiac support from outside of the heart without a direct blood contacting surface. The original material employed as the actuator of artificial myocardial assist devices was 100um fibred-shaped, which was composed of covalent and metallic bonding structure and designed to generate 4-7 % shortening by Joule heating induced by the electric current input. In this study, we focused on the synchronization of the actuator with native cardiac function, and the phase delay parameter was examined in animal experiments using Saanen goats. Total weight of the device including the actuator was around 150g, and the electric power was supplied transcutaneously. The device could be successfully installed into thoracic cavity, which was able to be girdling the left ventricle. The contraction of the device could be controlled by the originally designed microcomputer. The mechanical contraction signal input had been transmitted with the phase delay of 50-200 msec after the R-wave of ECG, and hemodynamic changes were investigated. Cardiac output and systolic left ventricular pressure were elevated with 20% delay of cardiac cycle by 27% and 7%, respectively, although there was smaller difference under the condition of the delay of over 30%. Therefore, it was suggested that the synchronization measures should be examined in order to achieve sophisticated ventricular passive/active support on physiological demand.

Hydrogen bonding in acetone clusters probed by near-edge x-ray absorption fine structure spectroscopy in the carbon and oxygen K-edge regions.

Hydrogen bonding in acetone clusters was investigated using near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and density functional theory calculations in the carbon and oxygen K-edge regions. The partial-ion-yield (PIY) curves of the cluster ions were measured as the NEXAFS spectra of acetone clusters. In the carbon K-edge region, the first resonance peak, which was assigned to the C(CO) 1s-->pi( *)(C=O) resonance transition, showed no substantial change in the PIY curves of the acetone clusters, while the C(CH3) 1s-->3ppi(CH(3)) excitation feature was found to be strongly suppressed. The selective suppression of the C(CH3) 1s-->3ppi(CH(3)) resonance transition can be explained by the change in the character of the 3ppi(CH(3)) orbital due to the C=O...H-C type of hydrogen-bonding interaction. On the other hand, the NEXAFS spectra of the acetone molecule and clusters were almost identical in the oxygen K-edge region, except for a small shift in the pi( *)(C=O) resonance of 0.13 eV, because the character of the pi( *)(C=O) orbital remained, regardless of the C=O...H-C hydrogen bonding interaction.

[Aortic root surgery in patients with previous aortic root or valve operations].

OBJECTIVES: To assess the operative indication, risk factors, procedures, and outcomes of aortic root surgery in patients with previous aortic root or valve surgery. PATIENTS AND METHODS: Between 1995 and 2007, aortic root surgery was performed in 137 patients. Thirty-five of those, who had previous root replacement, root remodeling or aortic valve surgery, were evaluated retrospectively. RESULTS: Indications for redo surgery included lesions at coronary artery reconstruction site after root procedures, aneurysmal formation or dissection of sinus Valsalva after aortic valve procedures, and prosthetic material infection. Two cases with prior graft infection died of sepsis, and one case with extended aortic dissection died of esophageal bleeding. Hospital mortalities were, hence, 8.6% in redo cases, which was comparable to 5.0% in primary root surgery cases. Multivariate risk factor analysis of root surgery revealed that preceding infective aortic root lesion was the only significant independent risk factor for postoperative mortality, whereas redo procedure per se was not a significant risk. CONCLUSIONS: Redo aortic root surgery can be performed with a reasonably low operative risk. Graft infection in patients with previous aortic root surgery remains a challenging lesion.

Efficacy of perfusion cooling of the epidural space and cerebrospinal fluid drainage during repair of extent I and II thoracoabdominal aneurysm.

AIM: The aim of this study was to evaluate spinal cord injury and mortality resulting from repair of extent I and II thoracoabdominal aneurysm. The authors compared patients operated under mild hypothermia with or without epidural perfusion cooling (EPC) and cerebrospinal fluid drainage (CSFD). METHODS: From 1988 to 2007, 116 patients underwent replacement of the thoracoabdominal aorta; the procedure was performed in 38 patients with the aid of mild hypothermia alone (group A), and in 78 patients with the aid of EPC, mild hypothermia and CSFD (group B). Two catheters for epidural perfusion cooling were inserted in group B, in which one catheter was inserted into the epidural space to infuse chilled saline, and the other was inserted into the subdural space to drain the cerebrospinal fluid and to measure temperature and pressure. There were no significant differences in mean age, etiology of aortic disease, and aneurysm extent between the two groups. RESULTS: There were no significant differences in cardiopulmonary bypass time, the lowest nasopharyngeal temperature and operation time between the two study groups. The incidence of spinal cord injury in group A (16.2%) was significantly higher than in group B (3.8%, P=0.03). Hospital mortality in groups A and B was 10.5% and 2.6%, respectively (P=0.08). There was no significant difference in postoperative complications between the two study groups. CONCLUSION: The combination of EPC and CSFD was effective in lowering the incidence of postoperative spinal cord injury in the repair of extent I and II thoracoabdominal aortic aneurysm.

Hydrogen bonding in methanol clusters probed by inner-shell photoabsorption spectroscopy in the carbon and oxygen K-edge regions.

Hydrogen bonding in methanol clusters has been investigated by using inner-shell photoabsorption spectroscopy and density functional theory (DFT) calculations in the carbon and oxygen K-edge regions. The partial-ion-yield (PIY) curves of H(CH(3)OH)(n)(+) were measured as the soft x-ray absorption spectra of methanol clusters. The first resonance peak in the PIY curves, which is assigned to the sigma*(O-H) resonance transition, exhibits a 1.20 eV blueshift relative to the total-ion-yield (TIY) curves of molecular methanol in the oxygen K-edge region, while it exhibits a shift of only 0.25 eV in the carbon K-edge region. Decreased intensities of the transitions to higher Rydberg orbitals were observed in the PIY curves of the clusters. The drastic change in the sigma*(O-H) resonance transition is interpreted by the change in the character of the sigma*(O-H) molecular orbital at the H-donating OH site due to the hydrogen-bonding interaction.

Sensorless control for a sophisticated artificial myocardial contraction by using shape memory alloy fibre.

The authors have been developing an artificial myocardium, which is capable of supporting natural contractile function from the outside of the ventricle. The system was originally designed by using sophisticated covalent shape memory alloy fibres, and the surface did not implicate blood compatibility. The purpose of our study on the development of artificial myocardium was to achieve the assistance of myocardial functional reproduction by the integrative small mechanical elements without sensors, so that the effective circulatory support could be accomplished. In this study, the authors fabricated the prototype artificial myocardial assist unit composed of the sophisticated shape memory alloy fibre (Biometal), the diameter of which was 100 microns, and examined the mechanical response by using pulse width modulation (PWM) control method in each unit. Prior to the evaluation of dynamic characteristics, the relationship between strain and electric resistance and also the initial response of each unit were obtained. The component for the PWM control was designed in order to regulate the myocardial contractile function, which consisted of an originally-designed RISC microcomputer with the input of displacement, and its output signal was controlled by pulse wave modulation method. As a result, the optimal PWM parameters were confirmed and the fibrous displacement was successfully regulated under the different heat transfer conditions simulating internal body temperature as well as bias tensile loading. Then it was indicated that this control theory might be applied for more sophisticated ventricular passive or active restraint by the artificial myocardium on physiological demand.

Morphological approach for the functional improvement of an artificial myocardial assist device using shape memory alloy fibres.

The authors have been developing a mechano-electric artificial myocardial assist system (artificial myocardium) which is capable of supporting natural contractile functions from the outside of the ventricle without blood contacting surface. In this study, a nano-tech covalent type shape memory alloy fibre (Biometal, Toki Corp, Japan) was employed and the parallel-link structured myocardial assist device was developed. And basic characteristics of the system were examined in a mechanical circulatory system as well as in animal experiments using goats. The contractile functions were evaluated with the mock circulatory system that simulated systemic circulation with a silicone left ventricular model and an aortic afterload. Hemodynamic performance was also examined in goats. Prior to the measurement, the artificial myocardial assist device was installed into the goat's thoracic cavity and attached onto the ventricular wall. As a result, the system could be installed successfully without severe complications related to the heating, and the aortic flow rate was increased by 15% and the systolic left ventricular pressure was elevated by 7% under the cardiac output condition of 3L/min in a goat. And those values were elevated by the improvement of the design which was capable of the natural morphological myocardial tissue streamlines. Therefore it was indicated that the effective assistance might be achieved by the contraction by the newly-designed artificial myocardial assist system using Biometal. Moreover it was suggested that the assistance gain might be obtained by the optimised configuration design along with the natural anatomical myocardial stream line.

Risk of facial splashes in four major surgical specialties in a multicentre study.

This study analyses the results of face-shield blood spatter contamination at six medical facilities to determine exposure risk when facial protection is not used. Blood spatter exposure was evaluated on the basis of overall incidence, location of spatter on face shields, surgical specialty, risk for operating room staff, length of surgery and volume of blood loss. Six hundred face shields were evaluated for blood spatter contamination by visual inspection as well as by staining with leucomalachite green. The face shield was divided into three regions: Orbital (O-region), Paraorbital (P-region) and Mask (M-region). Visual examination detected blood spatter contamination in 50.5% (303/600) of the face shields, whereas leucomalachite green staining detected blood contamination in 66.0% (396/600). Blood contamination was 36.6% (220/600) in the O-region, 37.8% (227/600) in the P-region and 57.0% (342/600) in the M-region. Among operating room staff, the incidence of blood spatter was greatest among lead surgeons at 83.5% (167/200), followed by the first assistant at 68.5% (137/200) and the scrub nurse at 46.0% (92/200). By specialty, cardiovascular surgery was at highest risk with an incidence of 75.3% (113/150) followed by neurosurgery at 69.3% (104/150), gastrointestinal at 60.0% (90/150) and orthopaedic surgery at 60.0% (90/150).

[Aortic root enlargement in elderly patients].

From January 2003 to June 2005, 12 elderly patients with severe aortic stenosis underwent aortic root enlargement (ARE) by Nicks procedure. Their ages ranged from 74 to 87 with a mean of 79.3. Stented bioprosthesis were used in 11 cases. There was no death. Cardiothoracic ratio on chest X-ray decreased from 59.4 to 53.6% and New York Heart Association (NYHA) functional class improved from 3.4 to 1.3. Echocardiography also showed remarkable improvement, in peak pressure gradient (PG) from 98.3 to 20.7 mmHg, in left ventricular mass index (LVMI) 181 to 137 g/m2. LVM and LVMI regression rates were 25.3 and 22.3%, respectively. Comparative study of those with ARE alone and those with combined operation showed much hazardous effect in the latter, but no significant difference in echocardiographic findings postoperatively. ARE by Nicks procedure, if it could be performed without concomitant procedure, is a safe and effective option also in elderly patients with small aortic annulus.

Development of an Artificial Myocardium using a Covalent Shape-memory Alloy Fiber and its Cardiovascular Diagnostic Response.

The authors have been developing a newly-designed totally-implantable artificial myocardium using a covalent shape-memory alloy fibre (Biometal®, Toki Corporation), which is attached onto the ventricular wall and is also capable of supporting the natural ventricular contraction. This mechanical system consists of a contraction assistive device, which is made of Ti-Ni alloy. And the phenomenon of the martensitic transformation of the alloy was employed to achieve the physiologic motion of the device. The diameter of the alloy wire could be selected from 45 to 250μm. In this study, the basic characteristics of the fiber of 150μm was examined to design the sophisticated mechano-electric myocardium. The stress generated by the fiber was 400gf under the pulsatile driving condition (0.4W, 1Hz). Therefore it was indicated that the effective assistance might be achieved by using the Biometal shape-memory alloy fiber.

Production of methyl-oxonium ion and its complexes in the core-excited (HC(O)OCH3)n clusters: H/H+ transfer from the alpha carbonyl.

Dissociation of free methyl-formate (MF), HC(O)OCH3, and its clusters (MF)n, (HC(O)OCH3)n, induced by core-level excitation was studied near the oxygen K edge by time-of-flight fragment-mass spectroscopy. Besides the protonated clusters, (MF)nH+ with n < or = 15, we identified the production for another series of (MF)mCH3OH2+ with m < or = 14 as well as methyl-oxonium ion, CH3OH2+, characteristic of hydrogen transfer reactions in the cationic clusters. Here; specifically labeled methyl-formate-d (MFD), DC(O)OCH3 was also used to examine the core-excited dissociation mechanisms. Deuterium-labeled experiments indicated that MFD+ with low internal energies, partially generated after the core excitation, produces CH3OD+ via a site-specific deuterium transfer from the alpha carbonyl in the molecular cation and that CH3OD2+ can be formed via the successive transfer of another deuterium from the neighbor molecule in the clusters. The deuteron (proton) transfer was also found to take place preferentially from the alpha carbonyl of the neighbor molecule for the production of deuteronated (MFD)nD+, (protonated (MF)nH+), clusters. The minimal energy requirement paths were examined for dimer (MF)2+ cation to support the present dissociation mechanisms of core-excited (MF)n clusters using ab initio molecular-orbital calculations.

[Staged total cavopulmonary connection following Starnes operation].

A three-year-old boy with Ebstein's anomaly, who had received Starnes operation in the neonate state, successfully underwent staged total cavopulmonary connection. Despite of hypoplasticity of the pulmonary artery, the postoperative cardiac catheterization showed no elevation of pulmonary artery pressure and good cardiac performance. Although he suffered from supraventricular tachycardia in the early postoperative period, subsequent course was uneventful.

[Spinal cord protection during most or all of descending thoracic or thoracoabdominal aneurysm repair].

OBJECTIVES: The purpose of this study is to evaluate usefulness of perfusion cooling for regional spinal cord hypothermia during most or all of thoracic or thoracoabdominal aneurysm repair. METHODS: From 1987 to 2003, 103 patients underwent most or all of thoracic or thoracoabdominal aneurysm repair. Forty-eight patients underwent operation using distal aortic perfusion, mild hypothermia and segment sequential repair (group MH). Fifty-five patients underwent the same operation as group MH except epidural perfusion cooling and drainage of cerebrospinal fluid (CSF) [group EC & CSFD]. The aorta was replaced sequentially in segment and several paris of intercostal and lumbar arteries were reconstructed in 2 groups. RESULTS: Cardiopulmonary bypass time of group MH and group EC & CSFD was averaged 235 and 241 minutes, respectively. The lowest CSF temperature in group EC & CSFD was averaged 24.7 degrees C, and the difference between nasopharyngeal and CSF temperature was averaged 6.4 degrees C. The rate of spinal cord injury of group MH and EC & CSFD was 10.4% and 3.6%, respectively. Hospital mortality of group MH and EC & CSFD was 8.3% and 5.5%, respectively. The incidence of spinal cord injury and hospital mortality of group EC & CSFD were decreased compared to them of group MH. CONCLUSION: We conclude that the perfusion cooling of epidural space and CSF drainage are effective method in reducing postoperative spinal cord injury.

Blalock-Taussig shunt for a neonatal case of Ebstein's anomaly with unobstructed right ventricular outflow tract.

A neonate with Ebstein's anomaly presented with severe cyanosis because of massive right-to-left shunt through an atrial septal defect and reduced blood flow through an unobstructed right ventricular outflow tract. This atypical patient underwent a right modified Blalock-Taussig shunt, which resolved the respiratory.

Safety and efficacy of epidural cooling for regional spinal cord hypothermia during thoracoabdominal aneurysm repair.

Twenty-four consecutive patients underwent epidural cooling as an adjunct to elective thoracoabdominal aortic repair under moderate systemic hypothermia. One patient suffered from postoperative paraplegia (4%), and another died from subarachnoidal hemorrhage (4%). Details of the technique, the associated care, and the pitfalls will be discussed.

[Aortobronchial fistula after replacement of descending thoracic aorta with ringed graft; report of a case].

A 79-year-old male patient complicated with aortobronchial fistula after replacement of descending thoracic aorta with ringed graft. He underwent replacement of the aortic arch using a four branched vascular graft and open stent grafting to replace the descending thoracic aorta after removing the ringed-graft through median sternotomy. This procedure is useful for patients as the left thoracotomy is risky and the distal anastomotic site of the descending thoracic aorta is too far to anastomose.