Cardiovascular Responses to Somatosensory Stimulation and Their Modulation by Baroreflex Mechanisms

Exposure of experimental animals to noxious somatic stimulations sometimes induces sustained hypertension. Information regarding the medullary projections of somatic afferents and the neurotransmitters involved in them is incomplete. The present investigation in urethane-anesthetized, artificially ventilated, adult male Wistar rats was undertaken to clarify some of these issues. It was observed that the inhibition of contralateral, ipsilateral, or bilateral rostral ventrolateral medullary pressor area (RVLM) with muscimol attenuated the pressor and tachycardic responses to sciatic nerve stimulation. Similar inhibition of the medial subnucleus of the solitary tract (mNTS) exaggerated the cardiovascular responses to sciatic nerve stimulation. Interruption of the baroreflex by microinjections of ionotropic glutamate receptor antagonists into the mNTS or barodenervation also exaggerated the responses to sciatic nerve stimulation. Unilateral stimulation of the aortic nerve blocked the cardiovascular responses to the sciatic nerve stimulation. These results indicated that in the rat, the ascending afferents in the sciatic nerve project bilaterally to the RVLM as well as mNTS; an excitatory amino acid, probably glutamate, is released in the mNTS in response to the sciatic nerve stimulation; and barodenervation or blockade of baroreflex in the mNTS exaggerates, while baroreceptor stimulation inhibits, cardiovascular responses to somatosensory stimulation.     

Acute Aortic Syndromes

Abstract

Acute aortic syndrome is a term that describes one of a number of different pathologic entities. Each of these conditions requires urgent or emergent evaluation and may possibly require surgical intervention. However, both entities may be unfamiliar to the nonsurgical (and in some cases, surgical) practitioner and they may mimic more common diseases or be missed entirely. An understanding of the processes, nomenclature, and management options is critical in optimizing patient care.     

Air Transport of Patients with Unstable Aortic Aneurysms Directly into Operating Rooms

Objective. The purpose of this study was to describe an air transport service's protocol for direct transport of patients with abdominal aortic aneurysm leak (AAAL) into receiving hospital operating rooms (ORs). Methods. This retrospective consecutive-case analysis examined AAAL patients undergoing nurse-paramedic Boston MedFlight (BMF) transport during 1999–2004, who were taken directly into ORs at four academic centers. BMF uses a rotating roster system to assign receiving hospitals when referring physicians have no preidentified receiving facility, but this practice may prolong patient transport or be associated with less diagnostic certainty, andthus more delay, at receiving hospitals. Thus, the study compared “Roster” versus “Non-roster” patients' time andoutcome end points. Continuous nonparametric data (e.g., time intervals) were described with median andinterquartile range (IQR). Chi-square andKruskal-Wallis tests were used for univariate comparisons; regression analysis assessed dependent variables while adjusting for covariates (e.g., transport mileage). Results. There were 29 direct-to-OR transports, with median distance of 30 miles. All patients had AAAL diagnosis confirmed; 51.7% survived. System performance for end points was similar as assessed between Roster versus Non-roster patients. Conclusions. Interfacility direct-to-OR transport of AAAL patients is feasible. Use of a roster system allows for timely transport facilitation for patients needing specialized care; roster patients achieve similar end points as did patients who had already-identified receiving hospitals upon air medical transport request.     

Stanford-A acute aortic dissection,inflammation, and metalloproteinases: A review

Acute aortic dissection (AAD) is a life-threatening disease with an incidence of about 2.6–3.6 cases per 100,000/year. Depending on the site of rupture, AAD is classified as Stanford-A when the ascending aortic thoracic tract and/or the arch are involved, and Stanford-B when the descending thoracic aorta and/or aortic abdominal tract are targeted. It was recently shown that inflammatory pathways underlie aortic rupture in both type A and type B Stanford AAD. An immune infiltrate has been found within the middle and outer tunics of dissected aortic specimens. It has also been observed that the recall and activation of macrophages inside the middle tunic are key events in the early phases of AAD. Macrophages are able to release metalloproteinases (MMPs) and pro-inflammatory cytokines which, in turn, give rise to matrix degradation and neoangiogenesis. An imbalance between the production of MMPs and MMP tissue inhibitors is pivotal in the extracellular matrix degradation underlying aortic wall remodelling in dissections occurring both in inherited conditions and in atherosclerosis. Among MMPs, MMP-12 is considered a specific marker of aortic wall disease, whatever the genetic predisposition may be. The aim of this review is, therefore, to take a close look at the immune-inflammatory mechanisms underlying Stanford-A AAD.     

Percutaneous endovascular treatment of aortic aneurysms: Clinical evaluation and literature results

Abstract

In this study we aimed to evaluate the efficiency of percutaneous endovascular aortic aneurysm repair (p-EVAR). Anatomically selected patients treated with a single 10Fr Perclose Prostar XL vascular closure device (VCD) were examined. Primary success rate and common femoral artery (CFA) open conversion (OC) requirement per sheath size used were recorded. A literature review on p-EVAR results was also performed. One-hundred patients were enrolled. Successful p-EVAR was achieved in 183 of the 196 CFA access sites (93.4%), and was specifically 85.9% and 98.3% for sheaths ≥20Fr and ≤18Fr respectively. There were 13 periprocedural complications (bleeding = 10, arterial dissection and thrombosis = 1, pseudoaneurysm = 2) all leading to OC. Use of ≥20Fr sheaths had significantly higher OC rate (P < .05). Reconstruction was achieved with primary repair (N = 11) and patch angioplasty (N = 2). Mean hospital stay was 1.8 days. The literature review (vascular closure of 2921 CFA access sites) revealed an overall technical success rate of 92.3%. Device related- were more common than patient related-OCs (P < .05). p-EVAR procedures are safe and feasible. Sheath size is a significant predictor of OC rate and more OCs might be expected with very large (≥20Fr) sheath sizes.     

Suture-mediated percutaneous closure of the arterial puncture site after abdominal aortic stent implantation

Summary

We report the use of a vascular surgical device to provide safe closure of the arterial access site after abdominal aortic-stent implantation. After suture-mediated percutaneous closure of the arterial puncture site, bleeding stopped immediately. There was no need for adjunctive compression. Immobilisation of the patient lasted only 1 h.     

Management of aortic valve disease in the presence of left ventricular dysfunction

The development of heart failure in patients with aortic valve disease is associated with increased mortality, unless aortic valve replacement is performed. There is an especially high risk of death among patients with low ejection fraction. The heart failure must be treated and the patient’s condition stabilized before surgery is performed. A delay in surgery, on the other hand, may lead to irreversible cardiac dysfunction and culminate in heart failure. Initial management must include an evaluation of the severity of the lesion and the functional state of the left ventricle. It is possible to achieve both of these goals simultaneously with echocardiography and pharmacologic challenge.     

Supravalvar aortic stenosis: current surgical approaches and outcomes

Supravalvar aortic stenosis (SVAS) is a congenital anomaly characterized by a discrete or diffuse narrowing of the ascending aorta. It may also be associated with right-ventricular outflow tract obstruction, aortic valve pathology and coronary ostial stenosis. While present in both familial and sporadic forms, it demonstrates a strong association with William–Beuren syndrome, both being anomalies associated with defects in the elastin gene. In this article, the authors have discussed the etiology, morphology, clinical presentation and genetic basis of SVAS. Various surgical approaches, both conventional and recent, have been discussed and demonstrated with the aid of diagrams. Single-, two- and three-sinus methods have been presented, along with a comparative analysis of early results, associated procedures, late mortality and reoperation. In conclusion, the authors have described their institutional experience of more than 40 years in the surgical management of SVAS.     

The valve patient and pregnancy

Pregnancy causes a significant and sustained increase in cardiac output that may be poorly tolerated in cases of underlying heart disease. Valvular stenosis is often poorly tolerated and may require intervention during pregnancy, percutaneous intervention being the favored option. Conversely, regurgitant valve diseases are generally well-tolerated. Pregnancy in patients who have previously undergone prosthetic valve replacement raises specific problems linked to anticoagulant therapy. The choice is difficult between oral anticoagulation, which carries a risk of embryopathy, and heparin therapy, which is safer for the fetus but is associated with a high thromboembolic risk for the mother. The diversity of cases highlights the need for appropriate evaluation of heart disease before pregnancy and close follow-up by specialized teams.