Treatment of chronic type B aortic dissection with endovascular stent-graft placement

A 74-year-old man with chronic aortic dissection was treated with an endovascular stent graft, fabricated from expanded polytetrafluoroethylene and a Z-stent. It was placed in the true lumen to close an entry tear. Closure was obtained immediately and thrombosis of the false lumen at the descending thoracic aorta was observed on computed tomography (CT) obtained 1 week later. No procedure-related complications developed. The patient is doing well with no adverse events including aortic rupture or aortic branch ischemia.

[Early and mid-term results of endovascular stent grafting for aortic aneurysms]

Early and mid-term clinical results of 28 cases of endovascular stent grafting for descending thoracic aortic aneurysms and 11 cases of abdominal aortic aneurysms are reported. Early clinical results: Among 28 patients (7 true thoracic aortic aneurysms, 3 pseudothoracic aortic aneurysms and 8 acute, 4 subacute, and 6 chronic aortic dissections), two patients (7.1%) with ruptured acute aortic dissection or ruptured infected pseudoaneurysm died in the perioperative period. Two of the remaining 26 patients experienced minor complications. Aneurysmal sacs or false lumens at the descending thoracic aorta were completely thrombosed in the 26 patients. One patient (9.1%) with a ruptured abdominal aneurysm died, and one of the remaining 10 patients had renal and peripheral emboli and peripheral vascular trauma. Inadvertent covering of the renal arteries occurred in another patient. Unless one patient had persistent endoleak, aneurysmal sacs in the 10 surviving patients were thrombosed. Mid-term clinical results: One aortic dissection at a different section of the descending aorta occurred 6 months after stent grafting for aortic dissection, and one patient died of pneumonia 3 months after stent grafting for an abdominal aortic aneurysm. CT scanning 6 months after stent grafting revealed a decrease in maximal aneurysmal size in 3 of 9 patients with true or pseudothoracic aneurysms and in 2 of 5 patients with abdominal aortic aneurysms. Five of 9 patients with stent grafting for acute or subacute dissection showed elimination of the false lumen in the descending thoracic aorta in a CT scan 6 months after grafting. One patient with a true thoracic aneurysm and one patient with an abdominal aortic aneurysm showed an increase in aneurysmal size in a CT scan 2 years and one year after treatment, respectively.

Afferent and efferent nerve activity of arterial baroreceptor reflex under nonpulsatile systemic circulation

We studied the changes in arterial baroreceptor reflex (ABR) afferent activity and efferent activity induced by nonpulsatile systemic circulation (NC) during total left heart bypass (TLHB) in rabbits. To evaluate the influence of the circuit priming fluid and exposure to NC, we directly measured aortic depressor nerve activity (ADNA) (n = 5) and renal sympathetic nerve activity (RSNA) (n = 5) before the start of partial left heart bypass (PLHB) (Before), after PHLB (After), and 5 min after the start of TLHB (During THLB) while maintaining the mean aortic pressure. The circuit priming fluid did not affect the ABR. ADNA exhibited periodic discharge at Before and After, but at During THLB, this periodic discharge transformed into a continuous discharge, and ADNA increased significantly. However, there were no significant differences in RSNA. Our results suggested that in the acute phase under NC, the ABR differed from that under natural circulation.

Regulatory mechanisms of calponin phosphorylation in endothelin-1-induced contraction of porcine coronary artery

Calponin is an actin-associated protein that appears to play an auxiliary regulatory role in the contraction of smooth muscle. We report here on the mechanisms for regulation of calponin phosphorylation in the endothelin-1-induced contraction of porcine coronary artery. Treatment of strips of porcine artery with endothelin-1 increased calponin phosphorylation and contraction in a concentration-dependent manner. The time course of the phosphorylation was biphasic, with the response to endothelin-1. The extent of phosphorylation reached a maximum within 5 min of stimulation with 10(-7)M endothelin-1 and then it declined rapidly to reach a minimum at 20 min. A potent inhibitor of protein kinase C, GF109203X, inhibited both calponin phosphorylation and contraction that were induced by endothelin-1 at 5 min, without an inhibition for myosin light chain phosphorylation. Protein phosphatase inhibitor, okadaic acid, had no effect on the extent of phosphorylation at 5 min, but it significantly inhibited the subsequent decrease in calponin phosphorylation. In contrast, in PDBu-treated strips of coronary artery, okadaic acid caused a significant steady increase of the extent of calponin phosphorylation. Our results suggest that calponin phosphorylation might be regulated by protein kinase C and okadaic acid sensitive protein phosphatases, in the endothelin-1-induced contraction of porcine coronary artery.

Endovascular stent-graft placement for the treatment of acute aortic dissection

BACKGROUND

The standard treatment for acute aortic dissection is either surgical or medical therapy, depending on the morphologic features of the lesion and any associated complications. Irrespective of the form of treatment, the associated mortality and morbidity are considerable.

METHODS

We studied the placement of endovascular stent-grafts across the primary entry tear for the management of acute aortic dissection originating in the descending thoracic aorta. We evaluated the feasibility, safety, and effectiveness of transluminal stent-graft placement over the entry tear in 4 patients with acute type A aortic dissections (which involve the ascending aorta) and 15 patients with acute type B aortic dissections (which are confined to the descending aorta). Dissections involved aortic branches in 14 of the 19 patients (74 percent), and symptomatic compromise of multiple branch vessels was observed in 7 patients (37 percent). The stent-grafts were made of self-expanding stainless-steel covered with woven polyester or polytetrafluoroethylene material.

RESULTS

Placement of endovascular stent-grafts across the primary entry tears was technically successful in all 19 patients. Complete thrombosis of the thoracic aortic false lumen was achieved in 15 patients (79 percent), and partial thrombosis was achieved in 4 (21 percent). Revascularization of ischemic branch vessels, with subsequent relief of corresponding symptoms, occurred in 76 percent of the obstructed branches. Three of the 19 patients died within 30 days, for an early mortality rate of 16 percent (95 percent confidence interval, 0 to 32 percent). There were no deaths and no instances of aneurysm or aortic rupture during the subsequent average follow-up period of 13 months.

CONCLUSIONS

These initial results suggest that stent-graft coverage of the primary entry tear may be a promising new treatment for selected patients with acute aortic dissection. This technique requires further evaluation, however, to assess its therapeutic potential fully.

Estimation of stress in child neglect from thymic involution

It is difficult to evaluate the extent of stress in cases of suspected child abuse/neglect in a medico-legal autopsy. We have previously reported that stress due to abuse/neglect was found to have led to thymic involution. To elucidate the influence upon thymocytes differentiation, we compared the proportion of the thymocyte subpopulation in the thymus of a neglected child with one in an age-matched control obtained from cardiac surgery. We found that the relative number of CD4+ CD8+ double positive (DP) thymocytes decreased in the neglected child. It was presumed that the selective decrease in the number of the immature DP thymocytes with CD3- to low bcl-2low caused the thymic involution in the neglected child. It was suggested that an alteration in the proportion of thymocytes subpopulation might be used as an index of stress in cases of child abuse/neglect.

[Completion pneumonectomy combined with graft replacement of thoracic aortic aneurysm by simple clamping]

A 59-years-old male patient who had left upper lobe partial resection 30 years ago. He was seen at the family physician because of cough. A chest X-ray was showing an abnormal mass shadow measuring 3 x 4 cm in left lower lobe like honey comb. And squamous cell carcinoma (SCC) was detected in his sputum. He was diagnosed as primary lung cancer and introduced to our department to have operation. Chest CT-scan was showing lung tumor suspected SCC measuring 4.3 x 2.6 cm in segment 8 faced chest wall. At the same time, we detected thoracic aortic aneurysm and subcarinal lymph node, but could not see where the boundary is, so it was hard to distinguish between parietal thrombus with thoracic aortic aneurysm and swelling subcarinal lymph node. We decided it swelling subcarinal lymph node by three-dimensional treated CT-scan. Aortic angiography was showing proximal descending aortic aneurysm measuring diameter was 4.5 cm. Abdominal CT-scan was showing infrarenal abdominal aortic aneurysm measuring diameter was 5.5 cm. He was diagnosed as primary lung cancer (It. S8, SCC) (cT2N2M0, Stage IIIB), thoracic aortic aneurysm, abdominal aortic aneurysm, and idiopathic pulmonary fibrosis, and had completion pneumonectomy (R 2 b) for primary lung cancer and graft replacement with aneurysm dissection for thoracic aortic aneurysm without extracorporeal circulation. In this operation, we could find swelling subcarinal lymph node measuring 5 x 3 cm instead of parietal thrombus with thoracic aortic aneurysm. Pathological examination diagnosed middle differential SCC and no metastasis from dissected lymph node (PT2N0M0, Stage I A).

Arterial baroreceptor afferent activity in nonpulsatile systemic circulation

We directly measured aortic depressor nerve activity (ADNA) in rabbits to investigate changes in arterial baroreceptor afferent activity (ABAA) in response to nonpulsatile systemic circulation (NC) during total left heart bypass (TLHB). ADNA was measured before and 5, 20, 30, 40, 50, and 60 min after the start of TLHB while maintaining the mean aortic pressure (MAP) at preestablished values (n=10). At 5 min, the ADNA was significantly increased compared to its baseline value. At 30 min, it was significantly decreased compared to its value at 5 min and thereafter remained the same. The ADNA was then measured before and 5 and 30 min after the start of TLHB under increased MAP (n=10). The results showed that the percentage changes in ADNA during TLHB were significantly less than that observed when the MAP was increased before TLHB. We conclude that ABAA acutely adapts to NC 30 min after its initiation, but changes in ABAA are depressed under NC combined with increased MAP.

[Results of surgical treatment for pT3 primary lung cancer]

We reviewed pT3 lung cancer for 86 cases (13.1%) out of 659 cases treated surgically for primary lung cancer between 1985 and march 1998. Five-year and ten-year survival rates for all pT3 cases were 48% and 40% respectively and those for pT3N0M0 cases were 67.2%. The operative mortality between 1990 and 1998 (2.4%) was better than that between 1985 and 1989 (6.7%). The extensive resection for pT3 lung cancer was evaluated to be appropriate. However, the prognosis of the patients who underwent combined resection of mediastinal pleura, pericardium or diaphragm was very poor. Five-year survival rate was significantly worse in patients with N2 disease (17.3%) than in patients with N0 disease (65.8%) (p < 0.05). Although the surgical indication for the patients with mediastinal pleura, pericardium or diaphragm disease and N2 disease is still controversial, there is not the extensive surgical indication.

Comparative studies of glycoprotein Ib in heparin coated and nonheparin coated extracorporeal circulation circuits

Contact between blood and artificial materials has various effects on blood. Impairment of platelet function is an especially important and well known effect, but its precise mechanism is not clearly understood. The authors constructed a circulation model to investigate the effect of extracorporeal circulation on platelet membrane glycoproteins (GPs), especially GP Ib, and to compare the changes in GP Ib in heparin coated (group C) and nonheparin coated (group N) circuits. As determined by flow cytometry, GP Ib in both groups decreased on initiating circulation, but the decrease in group N was significantly larger than that in group C. There was no observed change in GP IIb/IIIa levels in either group. The extent of shear stress induced platelet aggregation significantly decreased during circulation in both groups. Decreases in the extent of shear stress induced platelet aggregation were significantly less with the use of heparin coated circuits. In addition, the amount of GP Ib in the high speed pellet decreased progressively during circulation in both groups. In contrast, the amount of GP Ib in the Triton insoluble (low speed) pellet increased dramatically during circulation. However, expression of GP Ib in the Triton soluble platelet fraction was low in both groups. From the results, it was concluded that the cause of the decrease in platelet function during extracorporeal circulation is attributable to the internalization of GP Ib from the platelet surface inside the platelet. It also can be said that a heparin coated circuit is one effective means of controlling this change.

A heparin-coated circuit maintains platelet aggregability in response to shear stress in an in vitro model of cardiopulmonary bypass

Alterations in platelet aggregability may play a role in the pathogenesis of qualitative platelet defects associated with cardiopulmonary bypass (CPB). We circulated fresh heparinized whole blood through tubing sets coated with heparin (C group, n = 10) and through non-coated sets (N group, n = 10) as a simulated CPB circuit. Shear stress (108 dyne/cm2)-induced platelet aggregation (hSIPA), plasma von Willebrand factor (vWF) activity and platelet glycoprotein (GP) Ib expression were measured, before, during, and after this in vitro set up of circulation. In the two groups, the extent of hSIPA significantly decreased during circulation and was partially restored after circulation. Decreases in the extent of hSIPA were significantly less with use of heparin-coated circuits. There was an equivalent reduction in plasma vWF activity, in the two groups. Expression of platelet surface GP Ib decreased significantly during circulation and recovered after circulation. Reduction of surface GP Ib expression during circulation was significantly less in the C group than that in the N group. Decrease in surface GP Ib expression correlated (r = 0.88 in either group) with the magnitude of hSIPA, in the two groups. The progressive removal of surface GP Ib was mainly attributed to redistribution of GP Ib from the membrane skeleton into the cytoskeleton. Our observations suggest that use of heparin-coated circuits partly blocks the reduction of hSIPA, as a result of a lesser degree of redistribution of GP Ib.

Terminal warm blood cardioplegia improves cardiac function through microtubule repolymerization

BACKGROUND

To elucidate the mechanisms responsible for the beneficial effects of terminal warm blood cardioplegia, we studied dynamic change in microtubules induced by cold cardioplegia followed by rewarming. Further, we investigated the relationship between cardiac function and morphologic changes in microtubules caused by hyperkalemic, hypocalcemic warm cardioplegia during initial reperfusion.

METHODS

In protocol 1 isolated rat hearts were perfused at 37 degrees C with Krebs-Henseleit buffer (KHB). After 3 hours of hypothermic cardiac arrest at 10 degrees C, hearts were reperfused at 37 degrees C with one of two buffers: group C, 60-minute reperfusion with KHB (K+, 5.9 mmol/L; Ca2+, 2.5 mmol/L); and group TC, 10-minute initial reperfusion with modified KHB (K+, 15 mmol/L; Ca2+, 0.25 mmol/L), followed by 50 minutes of reperfusion with KHB. Cardiac function after reperfusion was determined as a percentage of the prearrest value. In protocol 2 hearts were perfused at 37 degrees C with KHB containing colchicine (10(-5) mol/L) for 60 minutes.

RESULTS

There was spontaneous contractile recovery after 10 minutes of initial reperfusion in hearts from group TC as well as improved cardiac function after 15, 30, and 60 minutes of reperfusion compared with that in group C. Immunohistochemical staining and immunoblot analysis demonstrated microtubule depolymerization during hypothermic cardiac arrest and complete repolymerization after 10 minutes of reperfusion with warm buffers in both groups. Colchicine-induced microtubule depolymerization is associated with deterioration of cardiac function.

CONCLUSIONS

One mechanism responsible for improved cardiac function mediated by terminal warm blood cardioplegia is the restart of contraction after complete microtubule repolymerization.

[Myocardial protection for cardiac reoperations in patients with valvular disease]

In cardiac reoperations, the less dissection needed, the less potential blood loss from divided epicardial adhesions and the less trauma to the heart. However, minimal cardiac dissection may result in inadequate topical cooling. Therefore the optimal delivery of cardiac solution has a great influence upon postoperative myocardial function in cardiac reoperations. We have examined the effect of the modified Buckberg's method compared to that of simple cold blood cardioplegia in valvular reoperations. In the cases of redo aortic valve procedures, antegrade-retrograde delivery of cardioplegic solution was done in the modified Buckberg's method. It was superior to simple cold blood cardioplegia in terms of the doses of dopamine needed when weaning from cardiopulmonary bypass and the ratio of spontaneous beating after aortic declamping. Nevertheless, myocardial protection measures for hypertrophied myocardium have not yet been established. In particular, reoperations for hypertrophied hearts pose many problems for cardiac surgeons. To achieve better cardiac function postoperatively, further investigations of hypertrophied myocardium are needed at the cellular or molecular level.

Primary leiomyosarcoma of the pulmonary artery confirmed by catheter suction biopsy

A patient with clinical features consistent with pulmonary embolism showed no improvement despite therapy with tissue-plasminogen activator and full-dose heparin. Transvenous catheter suction biopsy was successful in establishing an antemortem histologic diagnosis of primary pulmonary artery leiomyosarcoma. Urgent surgical intervention was performed.

Expression and degeneration of tenascin-C in human lung cancers

Tenascin-C is an extracellular matrix glycoprotein produced in response to epithelial-mesenchymal interactions during organogenesis and tissue remodelling. It has therefore been proposed as a stromal marker for epithelial malignancy. To test this hypothesis, 30 human lung cancers, presenting a variety of clinicopathological features, and six specimens of normal tissue were examined by Western and Northern blotting of tenascin-C protein and mRNA. The results obtained were: (1) elevated tenascin-C expression was detected in all 30 cases by Western blotting, with mRNA increase in 22 of them; (2) mRNA for a large isoform of tenascin-C, including an alternatively spliced sequence, was expressed in lung cancer tissues but not in normal lungs; and (3) metastasis to lymph nodes was frequently found in cases whose tenascin-C was degraded into small fragments. These results suggest that tenascin-C degradation can be used as a marker for metastatic potential of a tumour.

[Selection criterion of limited operation for lung cancer as a radical operation]

We reviewed partial resection and segmentectomy for 75 cases (6.5%) out of 1,212 cases treated surgically for primary lung cancer between 1957 and 1996. The surgical results of limited operation in radicality group and risk group was comparable to that of standard operation for the stage I lung cancer. Five-year survival of clinical stage I non-small cell lung cancer patients that tumor size is 2.0 cm or less was excellent (88.9%). Although risk group may be the best candidates for limited surgery, careful patient selection and theoretical operative procedure could make limited operation a standard procedure in radicality group.

Relief of mesenteric ischemia by Z-stent placement into the superior mesenteric artery compressed by the false lumen of an aortic dissection

In a 58-year-old man acute aortic dissection compromised the origin of the superior mesenteric artery (SMA), resulting in mesenteric ischemia. After failed balloon angioplasty a Gianturco Z-stent was placed. The stenosis improved immediately, followed by resolution of the clinical signs of mesenteric ischemia. SMA flow was well preserved 1 year after stenting.

[Surgical treatment for primary lung cancer in octogenarians: the role of limited operations]

34 octogenarians out of 1,214 cases treated surgically for primary lung cancer in our unit between 1957 and 1996. 12 patients underwent limited operation because they had one or more risk factors besides their age actor. We could suppress postoperative complications in octogenarians. 5-year survival rate in octogenarians was comparable to that in younger patients. The octogenarians underwent limited operations were better than those had lobectomies in 5-year survival rate and postoperative quality of life. So our surgical strategy for primary lung cancer in octogenarians was evaluated to be appropriate. However, we should improve the radicality of limited operation furthermore because 5-year survival rate for stage I non-small cell lung cancer was poor in octogenarians than in younger patients.

Clinical evaluation of a silicone coated hollow fiber oxygenator

In this article, the clinical experience with a cardiopulmonary bypass (CPB) using a newly developed hollow fiber oxygenator with an ultra-thin layer of silicone is reported. A comparative study of biocompatibility between the new oxygenator and a heparin coated oxygenator is also described. The CPB was performed with a silicone coated oxygenator, Mera Excelung Binding Prim HPO 15 H-C (Group I, n = 6) or Binding Prim HPO 25 H-C (Group II, n = 10) (Senko Medical Instrument Mfg., Tokyo, Japan). Air could be vented through the silicone coated hollow fibers, and it was easy to prime the circuits. The CPB duration was 101 +/- 37 min and 170 +/- 64 min for Groups I and II, respectively. There were no deaths and no complications from CPB. Partial arterial pressure of O2 levels 60 minutes after the start of CPB were 529 +/- 28 mm Hg and 529 +/- 28 mmHg for Group I and II, respectively. Partial arterial pressure of CO2 levels 60 min after the start of CPB were 36.4 +/- 4.6 mmHg and 39.4 +/- 4.4 mmHg, respectively. Plasma free hemoglobin at 60 min was 33.5 +/- 17.2 mg/ dL and 46.7 +/- 26.1 mg/dL for Groups I and II, respectively. As an evaluation of biocompatibility, the effects of the new oxygenator on platelet activation (GP Ib, IIb/IIIa), coagulation (TAT), fibrinolysis (PIC), and inflammatory response (C3a, granulocyte elastase) were investigated during CPB and comparing to those of the heparin coated oxygenator. There were no significant differences in GP Ib, GP IIb/IIa, TAT, PIC, and granulocyte elastase between the two oxygenators. However, 60 min after the start of CPB, the C3a was significantly lower for the new oxygenator group than for the heparin coated oxygenator group (p < 0.03). The new oxygenator showed good gas transfer, low hemolysis, and good biocompatibility. Because of its durability and good biocompatibility, the new oxygenator was determined to be suitable for prolonged extra corporeal circulation.