Rotating Motion of an Oil Droplet in a Circular Channel Subjected to a Transverse Alternating Electric Field.

The transient behavior of a silicone oil droplet passing through a circular channel in which castor oil passes as a surrounding fluid is investigated in both a periodically intermittent alternating electric field and a sinusoidal alternating electric field. When a periodically intermittent electric field with a low frequency and medium strength is applied, the droplet first undergoes ellipsoidal deformation where the major axis is oriented in the direction between the electric field direction and the direction normal to the electric field and electrorotation occurs. The inclined major axis tilts away from the electric field direction and then approaches it. For the case where a sinusoidal alternating electric field with medium strength is applied, electrorotation occurs when the frequency of the alternating sinusoidal electric field is low, whereas the droplet periodically deforms between a prolate and an oblate ellipsoid at certain frequencies. When the frequency of the electric field applied is high, the droplet remains spherical or undergoes deformation to a quasi-steady prolate ellipsoid with an aspect ratio of almost unity.

Management of cerebral malperfusion in surgical repair of acute type A aortic dissection.

OBJECTIVES: Cerebral malperfusion for patients with acute type A aortic dissection (AAAD) remains an unsolved problem. The present study aimed to evaluate our management of cerebral perfusion and identify predictors of perioperative cerebral malperfusion in patients undergoing surgical repair of AAAD. METHODS: Between January 2004 and December 2015, 137 consecutive patients with AAAD underwent aortic replacement at Tsuchiya General Hospital. The status of the dissected supra-aortic branch vessels (SABVs) was classified as patent or thrombosis by preoperative computed tomographic angiography. Intraoperative cerebral perfusion was monitored by transcutaneous carotid echo and regional oxygen saturation. In cases with neurological symptoms or cerebral malperfusion, quick cerebral perfusion was immediately started using a quick cutdown technique. We assessed clinical outcomes, including mortality and complications, and analysed predictors of early mortality and cerebral malperfusion. RESULTS: The early mortality rate was 8.0%. Postoperative cerebral injury was observed in 4 patients (2.9%). Nineteen patients had perioperative cerebral malperfusion. There were no postoperative cerebral injuries in the patients in whom intraoperative cerebral malperfusion was corrected. Multivariable analysis revealed that preoperative shock (odds ratio [OR] 22.60, P < 0.0001) and extension of dissection to the abdominal aorta (OR 9.31, P = 0.0064) were significant risk factors for early mortality. Preoperative neurological symptoms (OR 12.40, P = 0.0006) and partial or complete thrombosis of the SABV (OR 64.10, P < 0.0001) were identified as independent predictors of perioperative cerebral malperfusion. CONCLUSIONS: Perioperative cerebral perfusion should be carefully managed, especially in the patients with preoperative neurological symptoms or partial or complete thrombosis of the SABV.

[Aortoplasty with autologous pulmonary patch for the ascending aortic stenosis after interrupted aortic arch repair].

We experienced a case of ascending aortic stenosis after interrupted aortic arch repair. At the first operation in the neonatal period, diameter of the aortic annulus was 4.8 mm and no subvalvular stenosis was presented. Aortic arch was reconstructed with conventional technique of extended end-to-end anastomosis. Although ascending aortic stenosis was observed at the time, that had not been severe, however, the stenosis was exacerbated with time. At the catheterization 9 months after the operation, pressure gradient between aortic root and descending aorta was 72 mmHg. Therefore reoperation was carried out. Ascending aortoplasty using aoutologous pulmonary patch was performed. Pulmonary artery was repaired with aotologous pericardial patch. Despite mild pulmonary stenosis was observed, the postoperative course was favorable.

Periodic deformation of microsize droplets in a microchannel induced by a transverse alternating electric field.

When a water droplet is suspended in an immiscible, insulating liquid medium of essentially infinite dimensions and is subjected to a periodically alternating electric field, it will undergo periodic deformation at a frequency twice that of the field. This work examined the periodic deformation and bursting of microsize water droplets in silicone oil moving through a PTFE microchannel with an inner diameter nearly twice that of the droplets, under a periodically alternating electric field normal to the direction of flow. When the sinusoidal electric field was either relatively weak or had a low frequency, the droplets displayed periodic deformation alternating between a prolate ellipsoidal along the electric field direction and a sphere. In contrast, droplets alternated between prolate and oblate shapes when the electric field strength was high or the frequency of the electric field was high. When the applied electric field strength was increased, a constriction formed in the central portion of droplets which had deformed into a prolate ellipsoid. When the electric field strength was further increased, droplets broke into two or more smaller droplets as the result of the inertial force acting on the water in the droplet and the electrostatic force at the interface of the droplet and the surrounding liquid. The majority of the small droplets formed by such breakups subsequently merged into single droplets over the course of time.

[Total anomalous pulmonary venous connection with an unusual drainage vein from the right lung to the innominate vein;report of a case].

We encountered a case of total anomalous pulmonary venous connection with a drainage vein following an unusual course. The drainage vein, after emerging from the right lung, crossed the midline and drained into the innominate vein. Along the course of this vein, severe stenosis was present in the region wedged between the aortic arch and pulmonary artery, leading to severe pulmonary congestion. The common pulmonary vein was well developed. There was no other intracardiac malformation except atrial septal defect. No heterotaxy syndrome associated. Because echocardiography was unable to provide a complete picture of the pulmonary veins and drainage veins, multidetector-row computed tomography was performed to ascertain the anatomy. Emergency surgical intervention was carried out and anastomosis of the common pulmonary vein to the left atrium was performed. The postoperative course was favorable.

Early and midterm outcomes of open stent-graft treatment for distal aortic arch aneurysm.

PURPOSE: The aim of this study was to investigate early and late outcomes for open stent-graft treatment, which was introduced as a less-invasive technique for thoracic aortic aneurysm of the distal arch, and to clarify the validity of and indications for this treatment. MATERIALS AND METHODS: We retrospectively investigated 38 patients with thoracic aortic aneurysm of the distal arch who underwent open stent-graft placement at our hospital between June 2000 and September 2006. RESULTS: Five patients died in hospital (hospital mortality 13.2%). Age at the time of surgery and onset of postoperative paraplegia were identified as risk factors. Four patients (10.5%) had postoperative paraplegia, but no significant risk factors were seen. The size of the aneurysm was clearly reduced in 18 of the 25 patients (75.8%), in whom computed tomography was performed after discharge, and late outcomes were good. Mural thrombus thickness on the stent landing zone of <4 mm was a predictor for aneurysm shrinkage. Seven patients died during the late period, and the 5-year survival rate among hospital survivors was 80.1%. CONCLUSION: Early outcomes for open stent-graft are not necessarily good, and late survival is also not excellent. Open stent-graft thus cannot be regarded as an ideal technique for all patients with distal aortic arch aneurysm. However, after aneurysm shrinkage was confirmed during the early period, late outcomes were good. Absence of thick mural thrombus on the stent landing zone may represent a good indication for open stentgraft surgery.

Degree of fusiform dilatation of the proximal descending aorta in type B acute aortic dissection can predict late aortic events.

OBJECTIVE: Predicting the risk factors for late aortic events in patients with type B acute aortic dissection without complications may help to determine a therapeutic strategy for this disorder. We investigated whether late aortic events in type B acute aortic dissection can be predicted accurately by an index that expresses the degree of fusiform dilatation of the proximal descending aorta during the acute phase; this index can be calculated as follows: (maximum diameter of the proximal descending aorta)/(diameter of the distal aortic arch + diameter of the descending aorta at the pulmonary artery level). METHODS: Patients with type B acute aortic dissection without complications (n = 141) were retrospectively analyzed to determine the predictors of late aortic events; these include aortic dilatation, rupture, refractory pain, organ ischemia, rapid aortic enlargement, and rapid enlargement of ulcer-like projections. RESULTS: The fusiform index in patients with late aortic events (0.59) was higher than that in patients without late aortic events (0.53, P < .01). Patients with a higher fusiform index exhibited aortic dilatation earlier than those with a lower fusiform index. By multivariate analysis, we conclude that the predominant independent predictors of late aortic events were a maximum aortic diameter of 40 mm or more, a patent false lumen, and a fusiform index of 0.64 or more (hazard ratios, 3.18, 2.64, and 2.73, respectively). The values of actuarial freedom from aortic events for patients with all 3 predictors at 1, 5, and 10 years were 22%, 17%, and 8%, respectively, whereas the values in those without these predictors were 97%, 94%, and 90%, respectively. CONCLUSIONS: The degree of fusiform dilatation of the proximal descending aorta, a patent false lumen, and a large aortic diameter can be predominant predictors of late aortic events in patients with type B acute aortic dissection. Patients with these predictors should be recommended to undergo early interventions (surgery or stent-graft implantation) or at least be closely followed up during the chronic phase before such events develop.

Multiple coronary artery fistulas with a huge right coronary artery showing exacerbation during 16 years of follow-up.

A 38-year-old Japanese woman underwent cardiac evaluation to assess an arrhythmia detected after the delivery of her fourth baby. At the age of 22 years, she had undergone cardiac evaluation, including catheter examination, because of a heart murmur. Coronary angiography showed a huge right coronary artery (RCA) draining to the right atrium and a normal left coronary artery. Because the left to right shunt ratio was trivial and the patient was asymptomatic, conservative observation was undertaken. On the current admission to hospital, there was a grade III continuous murmur at the second left sternal border. The patient underwent right and left cardiac catheter examination in March 2000. Selective coronary angiography demonstrated an enlarged lumen of the RCA, an enlarged aneurysmal cavity in the terminal portion of the RCA, and the postero-descending artery being filled by collateral circulation from the left coronary artery. Moreover, 2 new fistulas had appeared from the left coronary system. An oxygen saturation study showed that the pulmonary to somatic flow ratio (Qp/Qs) was 2.2. The patient underwent surgical treatment in July 2000 and on coronary angiography 1 month later, there was no abnormal shunt flow from either coronary artery into the aneurysmal cavity, although the RCA was still enlarged.