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At least 73 records · Page 4Linked to original sources
PubMed1997

Release of 5-hydroxytryptamine by hypoxia from epithelioid cells of chicken thoracic aorta.

Epithelioid cells in the chicken thoracic aorta are shown to contain 5-hydroxytryptamine (5-HT) in immunocytochemical studies. To determine whether these cells act as chemoreceptors, as do type I cells of the carotid body, we examined the effects of hypoxia and acidosis on the release of 5-HT from the chicken thoracic aorta. Hypoxia caused the output of 5-HT in incubation medium. A reduction of pH to 6.8 failed to evoke 5-HT release. The response to hypoxia was inhibited by the removal of extracellular Ca2+ and by nifedipine and omega-conotoxin GVIA. These results suggest that epithelioid cells in the chicken thoracic aorta are chemoreceptors which sense a decrease in PO2 and then release 5-HT by Ca2+ influx through voltage-dependent L- and N-type Ca2+ channels. The epithelioid cells in the chicken aorta may be a useful model for pharmacological and physiological studies of 5-HT-containing cells.

Animals↗
PubMed2004

A novel, form-stable, anatomically curved vascular prosthesis for replacement of the thoracic aorta.

PURPOSE: Current replacement of the thoracic aorta performed with straight vascular prostheses may cause kinking, potentially affecting hemodynamics and promoting vortices and thrombus formation. A novel vascular prosthesis, resistant to pressure-related shape deformation, was designed to imitate the curved anatomy of the thoracic aorta. DESCRIPTION: A woven velour prosthesis was trimmed with cross-sutures along a marked line, resulting in a curved-shaped anatomic form, and was compared with conventional straight and thermally fixed curved grafts. The vascular prostheses were fixed at both ends at various base distances (8, 10, 12, 14, and 16 cm) and pressurized. To imitate the neck vessels an abutment was fixed at the upper convexity of the grafts. Radius of curvature or depth of kinking was measured at different pressures (100, 125, and 150 mm Hg). Pressure gradients and flow profiles were further analyzed in an aortic arch glass model. EVALUATION: When pressurized the straight and the thermally fixed protheses showed double kinking before and behind the abutment at all pressures and distances. Kinking depth increased with increasing pressure and less base distance. Transkinking pressure gradients increased with the degree of kinking. In a glass model flow profiles showed postkinking turbulences and vortex formation. The newly designed vascular prosthesis showed no kinking and remained form stable at all test conditions. CONCLUSIONS: This novel curved vascular prosthesis for replacement of the thoracic aorta demonstrates form stability compared with conventional straight and thermally fixed vascular prostheses in an aortic arch model, with smaller pressure gradients and flow disturbances.

Aorta, Thoracic↗
PubMed2000

Spontaneous rupture of the thoracic aorta.

BACKGROUND: Spontaneous rupture of the thoracic aorta without trauma, aneurysm, or dissection is an extremely rare but catastrophic disorder. Two cases of spontaneous aortic rupture are presented, both treated surgically with satisfactory results. METHODS: A review of the English literature found 16 patients with the diagnosis of spontaneous rupture of the thoracic aorta from 1961 through 1998. Eighteen reported cases, including the 2 cases presented herein, are reviewed. RESULTS: The representative clinical picture is one of a middle-aged hypertensive patient with acute chest pain and collapse, with imaging modalities demonstrating hemopericardium, hemomediastinum, or hemothorax. According to the reported experiences, aortography was accurate for identifying the rupture site although the findings were sometimes subtle. Misdiagnosis or nonsurgical management resulted in the patient's death. All 8 patients who did not undergo aortic repair died within 3 weeks after the onset, whereas 9 of 10 patients who underwent surgical aortic repair survived. CONCLUSIONS: For patients with a definitive or possible diagnosis of spontaneous rupture of the thoracic aorta, prompt operation is imperative through an optimal surgical approach to identify and repair the rupture site with appropriate circulatory support.

Aged↗
PubMed1985

Effects of chronic hypertension on vasa vasorum in the thoracic aorta.

The outer layers of the thoracic aorta receive substantial blood flow through vasa vasorum within the aortic wall. Flow delivered via these channels is functionally important because medial necrosis occurs when vasa vasorum are ligated. If flow through vasa vasorum is limited in chronic hypertension, this could contribute to medial necrosis and, perhaps, aortic dissection. In these experiments, flow and conductance in vasa vasorum were assessed in twelve awake dogs with renal hypertension (arterial pressure = 127 +/- 4 mmHg [mean +/- SE]) and nine normotensive controls (arterial pressure = 100 +/- 3 mmHg [P less than 0.001]). At rest, blood flow delivered via vasa vasorum to the thoracic aorta was similar in hypertensive and normotensive dogs (5.2 +/- 0.9 and 4.8 +/- 0.4 ml . min-1 X 100 g-1 respectively). Thus, in hypertensive dogs, conductance of the vasa vasorum decreased to maintain flow constant. During maximal dilatation induced by iv adenosine (4.7 mumol . kg-1 per min) flow delivered via vasa vasorum increased by 100% in both hypertensive and normotensive dogs. Calculations of maximum conductance indicate that vasodilator capacity was decreased by 67% in vasa vasorum of hypertensive dogs. These data suggest that vasodilator capacity of vasa vasorum in the thoracic aorta is limited in chronic hypertension. This abnormality could contribute to the pathogenesis of medial necrosis and aortic dissection in hypertensive patients.

Adenosine↗
PubMed2002

Endoluminal stent grafting of the descending thoracic aorta.

BACKGROUND: The timing and optimal therapy for descending thoracic aortic diseases still remain a challenging problem for surgeons. Nowadays endovascular treatment is becoming more and more popular both for acute as well as chronic cases. This technique is more respectful of the tissue integrity and avoids major and demolitive surgery for the patient. METHODS: In 1 year 32 patients presenting with descending thoracic aorta dissection (n = 25) or with descending thoracic aorta aneurysms (n = 7) were submitted to an endovascular procedure using covered stents. Ten of them were operated upon in general anesthesia whereas in 22 spinal anesthesia was administered. In neither group did anesthesia-related complications occur. RESULTS: In all cases in which endovascular treatment was possible, an endovascular stent was used for the treatment of the descending thoracic aorta disease. Only 1 patient had a major complication, which was a retrograde dissection of the ascending aorta surgically treated in an emergency setting. Our policy is to treat uncomplicated type B dissections in the subacute phase after 1 week of antihypertensive pharmacological treatment, but within 1 month of onset. Our mid-term follow-up shows very good results with no mortality and no stent-related complications. CONCLUSIONS: Stent grafting is replacing conventional surgery for descending thoracic aorta aneurysms and dissections. Our results suggest that in case of dissections, endovascular treatment should be delayed until the subacute phase, in the absence of complications. The risks and mortality are decreased.

Aged↗
PubMed2006

Intracellular cAMP: the "switch" that triggers on "spontaneous transient outward currents" generation in freshly isolated myocytes from thoracic aorta.

Spontaneous transient outward currents (STOCs) have been reported in resistance and small arteries but have not yet been found in thoracic aorta. Do thoracic aorta myocytes possess cellular machinery that generates STOCs? It was found that the majority of aortic myocytes do not generate STOCs. STOCs were generated in 8.7% of freshly isolated aortic myocytes. Myocytes that did not generate STOCs we have called "silent" myocytes and myocytes with STOCs have been called "active." STOCs recorded in active myocytes were voltage dependent and were inhibited by ryanodine, caffeine, and charybdotoxin. Forskolin was reported to increase STOCs frequency in myocytes isolated from resistance arteries. Forskolin (10 microM) triggered STOCs generation in 35.1% of silent aortic myocytes. In 36.8% percent of silent myocytes, forskolin did not trigger STOCs but increased the amplitude of charybdotoxin-sensitive outward net current to 136.1 +/- 8.5% at 0 mV. Membrane-permeable 8BrcAMP triggered STOCs generation in 38.7% of silent myocytes. Forskolin- or 8BrcAMP-triggered STOCs were inhibited by charybdotoxin. 8BrcAMP also increased open probability of BK(Ca) channels in BAPTA-AM-pretreated cells. Our data demonstrate that, in contrast to resistance arteries, STOCs are present just in the minority of myocytes in the thoracic aorta. However, cellular machinery that generates STOCs can be "switched" on by cAMP. Such an inactive cellular mechanism could modulate the contractility of the thoracic aorta in response to physiological demand.

Animals↗
PubMed2001

[Cerebrospinal fluid drainage and deep systemic hypothermia with total absence of circulation for spinal cord protection during surgery on the thoracic aorta].

A 53-yearold man with a dissecting aneurysm of Stanford's type-B or Crawford's type I measuring 8.5 cm in diameter underwent replacement of the distal descending aorta and the thoracic aorta using techniques for spinal cord protection involving deep hypothermia at 17 degrees C and lasting 38 minutes with total absence of circulation. A subarachnoid catheter was inserted at the lumbar level to monitor spinal fluid pressure as well as to provide drainage if pressure exceeded 10 mm Hg. During surgery 60 ml was drained, followed by 95 ml after surgery on the same day and 325, 262 and 169 ml on the following three days. No signs of neurological deficit were observed during the postoperative period. Clinical course was good until hypovolemic shock developed 27 days after the operation due to upper digestive tract bleeding caused by two duodenal ulcers that perforated the gastroduodenal artery. Emergency antrectomy and vagotomy were performed. The patient died from multiple organ failure. Spinal cord injury continues to be one of the most feared complications after excision of thoracic and thoracoabdominal aorta aneurysm. Currently, various ways of protecting the spinal cord are practiced, including drainage of cerebrospinal fluid, partial bypass of the femoral artery, intercostal artery reimplantation, drug therapy and local spinal and/or systemic hypothermia. These methods, together with shorter clamping time have achieved a reduction in the incidence of spinal cord injuries.

Aorta, Thoracic↗
PubMed1989

Cine-MR in dissection of the thoracic aorta.

Magnetic resonance imaging (MRI) of the thoracic aorta, including cine-MRI, was performed in 25 patients suspected of having dissection of the thoracic aorta. MRI was correlated with echocardiography, CT and angiography. The sensitivity of MRI (100%) was most closely followed by CT and angiography (83% and 77% respectively). The specificity of MRI and angiography was equally good, at 100% each. MRI was able to demonstrate the intimal flap in all 9 cases of aortic dissection, and there were no false-positive results. Differentiation of thrombosis and slow flow was possible on proton density images, gradient echo images permitted detection of the entry and re-entry sites. The nature of the dissection was determinated correctly in 8 out of 9 cases. MRI is capable of providing all the relevant parameters necessary to decide appropriate treatment of dissecting aneurysms of the thoracic aorta.

Adolescent↗
PubMed1977

Techniques of reinforcing the ascending thoracic aorta.

Two techniques of reinforcing the ascending thoracic aorta with Dacron vascular prosthetic material are described. Circular reinforcement has been used patients with fusiform dilatation of the ascending thoracic aorta in whom it was considered that graft replacement was unsuitable, and also in patients with a thin-walled aorta, where reinforcement was thought to be beneficial in preventing dehiscence of an aortic suture line. The techniques are described in two patients who underwent aortic valve replacement and who had aneurysmal dilatation of the ascending thoracic aorta.

Aged↗
PubMed1999

[Endovascular treatment in diseases of the thoracic aorta].

PURPOSE: To determine whether endovascular treatment of thoracic aorta conditions can be an effective alternative approach to surgical repair. MATERIAL AND METHODS: July 1997 to February 1999, eighteen patients (16 men and 2 women; 58.6 +/- 14.8 years) presenting with different kinds of descending aorta conditions were selected for the endovascular treatment. All patients exhibited severe comorbid pulmonary and/or cardiovascular medical conditions which increased surgical risk. All implants were performed in the operating room under fluoroscopic and TEE guidance. Clinical and imaging follow-up was performed 1, 3, 6 and 12 months later. RESULTS: The endovascular treatment was successful in 17 cases. No deaths or major complications occurred. No leakage was evident at post-procedure angiography. The patients were discharged after 6 +/- 4 days. MRI or CT study performed before hospital discharge showed aneurysms exclusion in 16 patients. In the four cases of dissection, thrombosis of the false lumen was evident since the first follow-up study. In the group of patients (11 cases) with 6 months follow-up, the diameters of stented aortic segments decreased. No late leakage was observed and thrombosis was complete in all cases. DISCUSSION: The natural history of aortic aneurysms and dissection is progressive toward dilation and aortic rupture. Surgery of descending thoracic aorta is burdened with a mortality of 8-12% in elective cases and over 50% in emergency cases or aortic dissection. The endovascular treatment of aortic conditions was introduced in clinical practice in 1991 and literature data show that it is effective, with lower mortality and morbidity rates than surgical treatment. CONCLUSION: Our results stress the feasibility and effectiveness of endovascular procedure in the treatment of complex thoracic aorta conditions even in high risk patients. Thus, endovascular treatment of thoracic aorta can be considered an effective alternative approach to conventional surgery.

Adult↗
PubMed2006

[Effect of cinobufacini on vascular contractile of rat thoracic aorta].

OBJECTIVE: To examine the effect of cinobufacini on rat thoracic aorta and its mechanism. METHODS: Isolated rat thoracic aorta was perfused and isometric tension was recorded by organ bath technique before and after cinobufacini treatment. RESULT: Cinobufacini induced contraction of isolated thoracic aorta with or without endothelium in a concentration-dependent manner (at concentration of 2.5,5.0,7.5,10.0 g/L). The vasoconstriction effect of cinobufacini was more potent in endothelium-denuded aorta ring [(16.3+/-3.39)%, (52.5+/-7.70)%, (60.9+/-8.84)%, (69.2+/-11.34)%] than in endothelium-intact aorta ring [(6.2+/-2.07)%, (14.7+/-4.91), (17.6+/-5.86)%, (20.3+/-6.78)% (P<0.01)]. Its contractile effect was attenuated in Ca(2+)-free solution (about 1/10 of that in buffer with 1.25 mmol/L CaCl(2)) or by the treatment with verapamil (10(-7)mol/L), an L-type calcium channel antagonist. Cinobufacini induced contraction on the endothelium-intact rat aorta was augmented by pretreatment with L-NAME (10(-4)mol/L), a nitric oxide synthase inhibitor. CONCLUSION: Cinobufacini contracts rat thoracic aorta by opening the voltage-dependent Ca(2+) channel and increasing Ca(2+) influx into vascular smooth muscle. Cinobufacini can also stimulate the release of vascular relaxant factor, nitric oxide, from the endothelium and thus antagonize cinobufacini-induced contraction.

Animals↗
PubMed2002

Stent graft repair in the aortic arch and descending thoracic aorta: a 4-year experience.

BACKGROUND: Thoracic aortic aneurysms (TAAs) and type B aortic dissections (ADs) are relatively frequent, serious conditions that are often managed nonoperatively because of perceived poor outcome of standard surgical reconstruction. Recently developed stent graft techniques represent a more attractive, less invasive option. We sought to determine the technical feasibility and safety of endovascular repair in the thoracic aorta with a retrospective review of our experience with such an approach. METHODS: Forty-seven patients received thoracic stent graft implants during the 4-year period ending March 31, 2002. All patients signed an Institutional Review Board-approved informed consent. Thirty-one patients had TAAs, and 16 had ADs. Device design and implant strategy were on the basis of evaluation of morphology with angiography and computed tomographic scan. The procedures were done with fluoroscopic guidance, with local anesthesia in five cases, spinal anesthesia in 19 cases, and general anesthesia in 23 cases. Endovascular access was achieved with femoral cutdown in 41 cases and a temporary iliac conduit in six cases. A Talent patient-specific device, with 4-mm to 6-mm oversize, was used in all. Proximal endograft attachment was in the descending thoracic aorta in 16 cases, parasubclavian in 21 cases, and the suprasubclavian aorta in 10 cases. Eight patients had adjunctive cervical reconstruction to transpose or revascularize the left subclavian or left common carotid arteries, enabling more proximal endograft attachment in the aortic arch. RESULTS: Access failure occurred in one patient (2.1%). One patient (2.1%) died within 30 days of access-related iliac artery rupture. Another death occurred at 60 days from a ruptured thoracoabdominal aneurysm with type I endoleak. No instances of paraplegia, stroke, or surgical conversion were seen. Five patients (TAA) were found to have endoleak on 30-day computed tomographic scan. Repair of type I endoleak was undertaken in three cases at 1, 4, and 6 months. Eight patients (17%) had adverse events within the first 30 days. Length of follow-up ranged from 1 to 44 months, with a mean of 18 months. Two patients were lost to follow-up, and one withdrew from the study. Four additional mortalities were observed, none related to the endograft or aortic pathology. CONCLUSION: Stent graft repair of TAA and AD is feasible and can be achieved with technical success and relatively low rates of perioperative morbidity and mortality. The Talent customized design proved versatile in various morphologies. More information is needed on indications, clinical efficacy, and long-term results.

Adult↗