Embolic events caused by aortic thrombi: An underestimated entity?

Stroke and other thromboembolic events are mainly caused by emboli from heart, aorta and other arteries. In this paper we describe a group of 5 middle-aged patients suffering from emboli caused by large thrombi in the aorta. Since the development of giant thrombi under high flow conditions in the aorta is a pathophysiological process which is not well understood, a model of flow distribution by numerically simulating the Navier–Stokes equation for an incompressible fluid was generated. This model simulated how such thrombi may develop in the aorta. We hypothesize that large thrombi issuing from the aortic vessel wall represent a underestimated entity in middleaged persons and are probably overlooked as the cause of stroke or other embolic events in some cases.     

Regional differences in serotonergic contractile sensitivity mediated by 5-HT2 receptors in rat aorta

The present studies examined serotonergic contractile sensitivity mediated by 5-HT2 receptors in thoracic and abdominal regions of rat aorta. Increasing concentrations of 5-HT (10 nM-100 microM) in the presence or absence of the selective 5-HT2 antagonist ketanserin (5 nM) produced differential concentration-response curves in thoracic and abdominal aortic ring preparations. Abdominal aortic preparations were significantly more sensitive to 5-HT than thoracic regions. Regional variations in maximal response produced by 5-HT were not observed. Ketanserin produced distinct rightward shifts in the 5-HT concentration-response curves, revealing a similar profile of sensitivity in thoracic and abdominal aorta. These data suggest that regional patterns in 5-HT-induced contractile responses in rat aorta are mediated by 5-HT2 sites exhibiting differential, site specific sensitivity.     

用供体腹主动脉行肝动脉重建小型猪肝移植模型的可行性研究

目的 探讨用供体腹主动脉行肝动脉重建小型猪肝移植模型的可行性.方法 取广西巴马小型猪10头(供、受体各5头),在取供体时,切取与腹腔动脉相连的一段腹主动脉,在供肝植入时用该段腹主动脉与受体腹主动脉吻合进行肝动脉重建,以获得植入肝理想的入肝血流.结果 5例受体巴马小型猪肝血流再通后在胆管吻合前均见金黄色胆汁流出,受体猪术后24 h均存活,手术获得成功.结论 在巴马小型猪的肝移植术中使用供体腹主动脉进行肝动脉重建是可行的,研究结果 为使用供体腹主动脉进行肝动脉重建的肝移植动物实验研究提供了重要基础.     

Acute aortic dissection and peripheral ischemia. Diagnostic and therapeutic problems. Remote control using nuclear magnetic resonance

This study concerns 7 cases of acute aortic dissection associated with visceral and/or lower limb ischemia. Only those cases are included which raised diagnostic and therapeutic problems. Patients were excluded who had purely angiographic involvement of an aortic branch and minor rapidly resolving ischemic syndromes. Five of the 7 patients presented type B (type III or distal) and 2 type A (type I or proximal) dissection. All patients received anti-hypertensor medical treatment. All but one had undergone surgery at least once at the acute stage. Five had been followed up and monitored by magnetic resonance imaging (MRI). One type A and 4 type B dissections were thus reviewed between the 15th month and the 9th year. Diagnostically, aortography was found to be inaccurate twice because of incomplete exploration of the thoracoabdominal aorta. Therapeutically, a case of intraoperative death occurred during replacement of the ascending aorta. Thus, out of the 6 patients who survived the acute stage, 4 are alive and asymptomatic, one has been lost sight of and the other died in year 5 after surgery for chronic dissecting aneurysm of the aortic arch. Among the 5 patients examined by MRI, 4 presented aortic ectasia, chronic dissecting aneurysm of the aortic arch and/or a descending aorta with a diameter between 45 and 65 mm. The patient with subnormal aortic diameter had his ascending aorta replaced (the follow-up period at this writing is only 27 months). Among 3 patients who were examined twice, one showed improvement after a year's interval, with a 5-mm increase in the caliber of the dissected aorta.(ABSTRACT TRUNCATED AT 250 WORDS)     

Attenuation of wave reflection by wave entrapment creates a "horizon effect" in the human aorta

Wave reflection is thought to be important in the augmentation of blood pressure. However, identification of distal reflections sites remains unclear. One possible explanation for this is that wave reflection is predominately determined by an amalgamation of multiple proximal small reflections rather than large discrete reflections originating from the distal peripheries. In 19 subjects (age, 35-73 years), sensor-tipped intra-arterial wires were used to measure pressure and Doppler velocity at 10-cm intervals along the aorta, starting at the aortic root. Incident and reflected waves were identified and timings and magnitudes quantified using wave intensity analysis. Mean wave speed increased along the length of the aorta (proximal, 6.8±0.9 m/s; distal, 10.7±1.5 m/s). The incident wave was tracked moving along the aorta, taking 55±4 ms to travel from the aortic root to the distal aorta. However, the timing to the refection site distance did not differ between proximal and distal aortic measurement sites (proximal aorta, 48±5 ms versus distal aorta, 42±4 ms; P=0.3). We performed a second analysis using aortic waveforms in a nonlinear model of pulse-wave propagation. This demonstrated very similar results to those observed in vivo and also an exponential attenuation in reflection magnitude. There is no single dominant refection site in or near the distal aorta. Rather, there are multiple reflection sites along the aorta, for which the contributions are attenuated with distance. We hypothesize that rereflection of reflected waves leads to wave entrapment, preventing distal waves being seen in the proximal aorta.     

Arterial 5-hydroxytryptamine transporter function is impaired in deoxycorticosterone acetate and Nomega-nitro-L-arginine but not spontaneously hypertensive rats

We reported upregulation of the 5-hydroxytryptamine (HT) transporter (5-HTT) protein in peripheral arteries from deoxycorticosterone acetate (DOCA)-salt hypertensive rats. We hypothesized that upregulated 5-HTT may be generally elevated in hypertensive models and, as a consequence, a higher basal concentration of 5-HT, the 5-HT metabolite 5-hydroxyindoleacetic acid, and an increased 5-HT uptake would occur in peripheral arteries of hypertensive rats compared with normotensive rats. We examined 3 hypertension models: DOCA-salt rats, Nomega-nitro-L-arginine (LNNA) rats, and spontaneously hypertensive rats (SHRs) in our study (systolic blood pressure [mm Hg]: DOCA (D)=197+/-6, SHAM(D)=112+/-4, LNNA (L)=228+/-9, SHAM(L)=128+/-2, SHR=172+/-7, and Wistar-Kyoto [WKY]= 121+/-3). High-pressure liquid chromatography measurements showed lower basal 5-HT concentrations in aorta from DOCA-salt and LNNA rats compared with their SHAM rats but not in SHR compared with WKY. In all of the 5-HT-uptake studies, we used arteries isolated from rats treated with the monoamine oxidase-A inhibitor pargyline to minimize 5-HT metabolism. Exogenous 5-HT was taken up by aorta, and this was inhibited by the 5-HTT inhibitor fluoxetine (1 micromol/L) or fluvoxamine (1 micromol/L). Total 5-HT uptake and 5-HTT-dependent active 5-HT uptake were decreased in aorta from DOCA-salt and LNNA rats compared with SHAM rats, but this was not observed in SHRs compared with WKYs. Western analysis revealed similar expression of 5-HTT in aorta from WKYs and SHRs as opposed to an upregulated 5-HTT in aorta from DOCA-salt and LNNA-hypertensive rats. Our study suggested that an altered serotonergic system by impaired 5-HTT function might play a role in blood pressure regulation in DOCA-salt and LNNA-hypertensive rats.     

Genetic basis of thoracic aortic aneurysms and dissections

The major diseases affecting the aorta are aortic aneurysms and dissections, which are classified based on anatomic location. Diseases affecting the ascending aorta, such as thoracic aortic aneurysms and type I and II dissections, are primarily associated with medial necrosis on pathologic examination. Medial necrosis is characterized by fragmentation and loss of elastic fibers, loss of smooth muscle cells, and interstitial collections of collagenous tissue and basophilic ground substance. Medial necrosis occurs as part of the normal aging of the aorta but is accelerated by other conditions, including hypertension and genetic alterations that predispose persons to these aortic diseases. The etiologies of many of the genetic syndromes, such as Marfan syndrome, that predispose persons to thoracic aortic aneurysms and dissections are understood. Studies are just beginning to elucidate the genes that predispose persons without known syndromes to these aortic diseases, and a major locus for this condition, termed the TAAD1 locus, has been mapped to 5q13-14. Future characterization of this gene and others will enhance the ability to determine persons at risk for aortic aneurysms and dissections and will define molecular mechanisms involved in the pathogenesis of this disorder.     

Coxsackievirus B cardiopathy and angiopathy in the hypercholesterolemic host.

Studies on the pathogenic potential of the human cardiotropic enterovirus, coxsackievirus B5, show that this agent localizes and replicates in the aorta of mice. Nutritionally-induced hypercholesterolemia leads to an increased replication and persistence of virus in tissues, specifically the aorta. Coxsackievirus B cardiopathy is markedly augmented in the hypercholesterolemic host, resulting in a persistent cardiomyolysis which is not evident in virus-infected animals with normal cholesterol levels. Pathological changes in the aorta become evident only months after the acute infection, and only in hypercholesterolemic animals previously infected with coxsackievirus B5. Our findings of coxsackievirus B-induced angiopathy and cardiopathy in the hypercholesterolemic host extend the known pathogenic range of these human viruses, and further emphasizes their potential as etiological agents of cardiovascular disease.     

Treatment of type A aortic dissection by exclusive gluing. Long-term results apropos of 15 patients

Between 1984 and 1988, 15 patients with a type A aortic dissection were treated with direct suturing of the entry opening of the dissection and gluing of the dissected aortic layers using the GRF glue (gelatine-resorcine-formaldehyde), without prosthetic replacement. An associated aortic insufficiency, in 10 patients, was treated with valve replacement (5 patients) or plasty (5 patients). Deep hypothermia with circulatory arrest were necessary in 10 patients whose dissection reached the ascending aorta. All patients survived the procedure. These patients are followed from 6 to 44 months. They are all controlled by echo-Doppler. In addition, ten had an angiography, 6 a control scan and 5 a NMR. In twelve patients, the ascending aorta as well as the aortic junction are normal. A limited aortic dissection which did not require a secondary procedure, is found in 3 patients. A dissection of the descending aorta is present in 10 patients. Two patients had to be re-operated: one, for a valve replacement, 18 months later; the other, for a myocardiopathy at the terminal stage, 14 months later, requiring an orthotopic transplantation. These results show that gluing of the aorta is an easy and effective treatment in type A aortic dissections.     

The obstructive subaortic conus

Eleven children are reported who had stenosis under a malposed aorta with gradients of 20 to 76 mm Hg between the right ventricle and aorta. The subaortic obstruction was caused by hypertrophy of the foreshortened infundibulum and malalignment of the infundibular septum relative to the remainder of the ventricular septum. Of these 11 patients, nine had a ventricular septal defect and seven had coarctation of the aorta. Rightward deviation of the infundibulum and aorta produced an unusually long left main coronary artery that was compressed by the stent of a bioprosthetic conduit valve in one patient. Serial cardiac catheterization studies in four patients showed progressive stenosis in each. Subaortic stenosis can develop in patients with malposition of the aorta and the frequency may be greater than 5% since milder forms are likely to occur. The obstruction can be progressive. The left coronary artery may be particularly vulnerable to compression after operative repair with an extracardiac conduit.     

Syndrome of chronic obstruction of the abdominal aorta and its surgical treatment]

The surgical management of 53 patients with high chronic occlusion of the abdominal aorta is reported. The authors unite this pathology under the term "chronic abdominal aorta obstruction syndrome". In 10 patients eversion endarterectomy was performed, in 22--aortofemoral bypass, in 21--prosthetic replacement of the aorta and of the iliac arteries with synthetic grafts. An original techinque of "milking" the thrombus down from the proximal aorta is described; it simplifies the operative procedure and prevents grave complications during surgery in patients with high occlusions of the abdominal aorta. Good results in the immediate postoperative period were achieved in 85% of the cases. Postoperative mortality comprised 12%. Late results were followed-up in 35 patients during 1 to 5 years. In 28 patients the results of surgery proved good.     

Kinetics of alpha-adrenoreceptor blockade by phentolamine in the normal and denervated rabbit aorta and rat vas deferens.

The rates of onset and offset of alpha-adrenoreceptor blockade by phentolamine (5 X 10(-7) M) have been studied on the normal and denervated rabbit aorta and rat vas deferens. Removal of the adventitia with its accompanying sympathetic nerve component results in an approximately threefold increase in the rate of onset of alpha-adrenoreceptor blockade by phentolamine in the rabbit aorta. The rate of offset of blockade by the antagonist on the aorta is likewise faster after the adventitia has been removed (approximately threefold faster for loss of 90% of the antagonist from the region of the receptors). This effect is not likely to be attributed to the absence of sympathetic nerve terminals since surgical denervation of the rat vas deferens has no effect on the kinetics of receptor blockade in this densely innervated organ. These data suggest that the adventitia of the rabbit aorta may serve as a diffusion barrier which limits the antagonist's access to, and efflux from, the region of the receptors. The dissociation constant of phentolamine (calculated from the equilibrium dose ratio) on the alpha-adrenoreceptor is unaltered by denervation in either tissue and is identical in both tissues. It is suggested that alpha-adrenoreceptors in the rabbit aorta and rat vas deferens are of a single type and are not significantly affected, with respect to antagonist affinity, by denervation.     

A dissecting aortic aneurysm in a female patient with Turner syndrome

Female phenotype, sexual infantilism, small stature and stigmatization are typical for patients with Turner's syndrome (TS). The most frequent cardiovascular manifestations in these patients are a bicuspidal aortal valve and coarctation of the aorta. In 5% patients dilatation of the aorta is found which can develop into a dissecting aneurysm. In the submitted case-history the authors describe a 34-year-old patient where the diagnosis of TS was proved only in adult age at the time when a dissecting aneurysm of the aorta was detected. The submitted case-history supports the recommendation of regular echocardiographic check-up examinations of patients with TS.     

RGS5, RGS4, and RGS2 expression and aortic contractibility are dynamically co-regulated during aortic banding-induced hypertrophy

Overexpression of regulator of G protein signaling 5 (RGS5) in arteries over veins is the most striking difference observed using microarray analysis. The obvious question is what arterial function might require RGS5. Based on functions of homologous proteins in regulating cardiac mass and G-protein-coupled receptor (GPCR) signaling, we proposed that RGS5 and vascular expressed RGS2 and RGS4 could participate in regulating arterial hypertrophy. We used the suprarenal abdominal aorta banding model to induce hypertension and hypertrophy. All 3 RGS messages were expressed in unmanipulated aorta with RGS5 predominating. After 2 days, thoracic aorta lost expression of RGS5, 4, and 2. At 1 week, all three returned to normal, and at 28 days, they increased many fold above normal. Valsartan blockade of angiotensin II (angII)/angII type 1 receptor signaling prevented upregulation of RGS messages but only delayed mass increases, implying wall mass regulation involves both angII-dependent and angII-independent pathways. The abdominal aorta showed less dramatic expression changes in RGS5 and 4, but not 2. Again, those changes were delayed by valsartan treatment with no mass changes. Thoracic aorta contraction to GPCR agonists was examined in aortic explant rings to identify vessel wall physiological changes. In 2-day aorta, the response to Gαq/i agonists increased above normal, while 28-day aorta had attenuated induced contraction via Gαq/i agonist, implicating a connection between RGS message levels and changes in GPCR-induced contraction. In vitro overexpression studies showed RGS5 inhibits angII-induced signaling in smooth muscle cells. This study is the first experimental evidence that changes in RGS expression and function correlate with vascular remodeling.     

Assessment of atherosclerotic lesions and distensibility of the thoracic aorta in familial hypercholesterolemia by biplane transesophageal echocardiography]

Atherosclerosis involving the thoracic aorta frequently occurs in patients with familial hypercholesterolemia (FH). In this study, we employed two-dimensional (2-D) transesophageal echocardiography (TEE: 5 MHz) to assess atherosclerotic lesions of the thoracic aorta in 9 patients with FH (47.8 +/- 10.3 yrs) and 11 age-matched normal control subjects. Biplane TEE probe (i.e., transverse or sagittal scan transducer) was used to permit direct imaging of the distal half of the ascending aorta. The atherosclerotic lesions were classified based on the severity of the aortic wall sclerosis as intimal thickening (I.), atheromatous plaque, (II.) and calcification (III.). In all of the patients with FH, atherosclerotic lesions of grade I. or greater were observed particularly in the aortic arch and descending aorta, while, lesions more severe than grade I. in the thoracic aorta were not observed in any of the control subjects. In 6 FH patients (67%), atherosclerotic lesions more severe than grade II. were frequently observed, which were more frequent in the aortic arch and descending aorta than in the ascending aorta.     

Contrasting effects of phorbol esters on serotonin- and vasopressin-evoked contractions in rat aorta and small mesenteric artery.

Phorbol esters, which activate protein kinase C, modulate vasoconstrictor-induced tension in vascular smooth muscle. We examined the effects of phorbol esters (phorbol 12,13-dibutyrate [PDBu] and 12-O-tetradecanoylphorbol 13-acetate [TPA]) on receptor agonist (serotonin [5-HT] and arginine vasopressin [AVP])-, high K(+)-, and caffeine-induced contractions in rings of rat aorta and a small (second-order) branch of the superior mesenteric artery (SMA). PDBu and TPA significantly augmented agonist-evoked contractions in aorta but diminished those in SMA. For example, 30 nM PDBu increased 5-HT- and AVP-evoked contractions 2.0-2.5-fold in aorta (p less than 0.01) but decreased 5-HT- and AVP-induced contractions by 40-60% in SMA (p less than 0.01). In contrast, PDBu and TPA amplified high K(+)- and 10 mM caffeine-induced contractions in both aorta and SMA. Augmentation of agonist-induced contractions by PDBu was greater in endothelium-denuded aorta than in intact aorta. Two protein kinase C antagonists, H-7 and staurosporine, inhibited 5-HT-evoked contractions in the absence as well as in the presence of PDBu in both types of arteries. The augmentation of contractile responses to caffeine and K+ by phorbol esters in both types of arteries suggests that the phorbols increase the sensitivity of the contractile apparatus to Ca2+, probably by activating protein kinase C. However, the inhibitory effects of phorbols on 5-HT- and AVP-evoked responses in SMA suggest that under these conditions the dominant effect of the phorbols is a marked reduction in the availability of Ca2+ in the SMA but not in the aorta.     

Ascending to descending aorta bypass for middle aortic syndrome.

Though stenoses of the descending aorta and its branches are seen with congenital anomalies or systemic inflammation, occlusion of the descending aorta is extremely rare. A patient with an occluded hypoplastic descending thoracic aorta required re-operation because of graft failure between the descending thoracic aorta and the infrarenal abdominal aorta. The etiology of the aortic occlusion in this case is unknown, but inflammation, such as Takayasu disease, is speculated.     

Expression levels of TRPC1 and TRPC6 ion channels are reciprocally altered in aging rat aorta: implications for age-related vasospastic disorders

We previously showed that the expression of transient receptor potential canonical (TRPC)6 ion channel elevated when TRPC1 was knocked down in A7r5 cultured vascular smooth muscle cells. Therefore, the purpose of this study was to explore whether TRPC6 is also upregulated in aging rat aorta comparable to that of TRPC1 in longitudinal in vivo aging model. We further investigated a possible causal relationship between altered phenylephrine-induced contractions and the expression levels of TRPC6, a purported essential component of alpha-adrenergic receptor signaling in aging aorta. Immunoblot analysis showed that TRPC1 protein levels significantly decreased whereas TRPC6 increased drastically in aorta from 16- to 20-month-old rats compared to that from 2 to 4 months. Immunohistochemical data demonstrated spatial changes in TRPC6 expression within the smooth muscle layers along with increased detection in the adventitia of the aged rat aorta. The phenylephrine-induced contractions were potentiated in aging aorta. In conclusion, based on this aging model, TRPC6 overexpression could be related with TRPC1 downregulation and might be responsible for the increased adrenoceptor sensitivity which contributes to the development of age-related vasospastic disorders.