Current interventional cardiology reports最新文献

With respect to neural control of the heart, intrathoracic ganglia and their interconnections form the final common pathway for autonomic modulation of regional cardiac function. In this review, data are presented indicating that such ganglia that include those distributed on the heart contain afferent (sensory) and efferent (motor) neurons that intercommunicate via local circuit neurons. The intrathoracic reflexes involving these neurons function in a coordinated fashion with central neurons located in the spinal cord, brain stem, and supraspinal central neuronal regions to regulate cardiac output on a beat-to-beat basis. The focus of this review is the putative role that these various populations of intrathoracic neurons play in regulating normal cardiac function and, in particular, how their interactions can become altered following their decentralization or in the presence of altered regional cardiac function. It is proposed that a thorough understanding of the interactions that occur among the hierarchy of neurons within intrinsic cardiac and intrathoracic extracardiac ganglia is required in order to assess cardiac regulation in normal as well as diseased states.

Vascularization is an exciting and complex mechanism involving angiogenesis and arteriogenesis. The role of homeostasis in the extracellular matrix (ECM) cannot be overemphasized. The delicate balance of metalloproteinases and their inhibitors is of utmost importance during vascularization within the unstable plaques. ECM degradation initiates the cascades of angiogenesis, especially near the thin fibrous cap, which can lead to rupture and intraplaque hemorrhages and acute coronary syndromes. The constant injury and response to injury to the vessel wall causes this natural repair and healing process to go awry with devastating clinical outcomes. With gene transfer it is now possible to have a positive impact on the treatment of those for whom traditional revascularization procedures have failed, and we are witnessing the benefits of many years of basic scientific research.

The HELEX Septal Occluder (W.L. Gore and Associates, Flagstaff, AZ) is a new device with many desirable characteristics. These include direct placement of the delivery catheter across the septal defect without the need for a long sheath; rounded, flexible and atraumatic shape; easy deployment while maintaining the ability to withdraw the device back into the delivery system at any time prior to release; safety cord to allow for removal of the device even after release from the formed elements of the delivery system; and highly biocompatible expanded polytetrafluoroethylene (ePTFE) covering. The design of the device has been thoroughly tested by computer modeling, in vitro testing, and in vivo evaluations in an animal model of atrial septal defect (ASD). Early human experience in Europe for ASD and patent foramen ovale (PFO) indications has been encouraging. Food and Drug Administration (FDA) trials in the United States are anticipated this year.

Renal artery stenosis (RAS) is a common cause of hypertension and renal insufficiency, especially in the elderly population. There are several excellent diagnostic tests available to diagnose RAS. Renal artery duplex ultrasound, magnetic resonance angiography (MRA), and spiral CT angiography have been shown to have excellent sensitivity and specificity for diagnosing renal artery disease. What test is used as a first-line screening test depends on factors such as degree of renal insufficency, cost, and experience and expertise in one's institution.

Percutaneous transluminal angioplasty and stenting of supra-aortic atherosclerotic vascular obstructions is becoming relatively common in the innominate, subclavian, and carotid arteries. However, percutaneous revascularization of atherosclerotic vertebral artery disease is an infrequently used treatment option. We believe that angioplasty and stent placement of posterior circulation, symptomatic, vertebrobasilar atherosclerotic disease is a safe and effective approach which avoids the morbidity associated with major surgery. Surgical revascularization of symptomatic vertebral artery stenosis is rarely performed due to limited surgical success and increased surgical morbidity. Balloon angioplasty alone or combined with stenting is associated with high success rates and low restenosis rates, although there is a scarcity of published peer-reviewed data. Series of endovascular stent placement in vertebral arteries alone for the treatment of posterior circulation ischemia is unpublished.Typical posterior circulation (vertebrobasilar) ischemic symptoms include diplopia, dizziness, drop attack, gait disturbance, or a transient ischemic attack. Initial treatment is with anticoagulation or antiplatelet therapy. We believe primary stent placement is the treatment of choice for vertebral artery revascularization due to the high technical success rate, low incidence of morbidity and mortality, and long-term durability.

Cilostazol, an antiplatelet agent developed in Japan, has been demonstrated to have the potential to reduce restenosis after percutaneous transluminal coronary angioplasty (PTCA). Unlike conventional antiplatelet agents, cilostazol has several favorable properties in reducing restenosis. Besides the vasodilatory effect, cilostazol directly inhibits smooth muscle proliferation and may enhance reendothelialization after PTCA. Although the magnitude of prevention of restenosis may differ with the PTCA device used, cilostazol appears quite promising as a pharmacologic treatment adjunct to PTCA.

Although revascularization of renal artery stenosis (RAS) from fibromuscular dysplasia (FMD) generally yields satisfying outcomes, traditional approaches to revascularization for atherosclerotic renal artery stenosis (ARAS) have been suboptimal because of the invasiveness, relatively high perioperative morbidity and mortality rates of surgery, and the low rates of technical success and long-term patency with percutaneous renal balloon angioplasty (PTA). Endovascular stents have been deployed for failed PTA (unsatisfactory results or complications) and treatment of restenotic lesions. Compared to PTA, primary stenting of ostial ARAS gives superior technical success rates greater than 95% and improved long-term patency. Curing hypertension after RAS revascularization is rare (< 10%). Improved control with fewer medications is a more realistic goal. Renal function as judged by serum creatinine improves in 20% to 30%, stabilizes in 40% to 60%, and deteriorates in 20% to 30% of patients whose renal function is impaired initially. One study demonstrated successful stenting slowed the rate of progression of renal failure in 89% of patients whose serum creatinine was less than 400 mol/L. Complications of renal artery stenting may be substantial, though procedure-related mortality is low. Patient selection for renal revascularization remains controversial. Those with renovascular disease and uncontrolled hypertension, progressive renal failure, or recurrent flash pulmonary edema should be carefully considered for renal artery stenting in experienced centers.

Restenosis after percutaneous intervention remains a significant clinical problem. Although stent implantation has significantly reduced the rate of restenosis by approximately 25% to 33%, intimal hyperplasia within stents still limits long-term vessel patency. The clinical sequelea of this neointimal proliferation is more pronounced in certain patient subgroups, eg, patients with diatbetes mellitus, diffuse disease, smaller vessels, chronic total occlusions, and lesions located in saphenous vein bypass grafts. Pharmacologic agents studied to date have failed to prevent restenosis. Tranilast, a novel anti-inflammatory agent, interferes with the proliferation and migration of vascular smooth muscle cells (VSMCs) induced by platelet-derived growth factor and transforming growth factor beta-1. Basic and preliminary clinical studies conducted with tranilast in Japan have shown encouraging results in terms of reducing restenosis. The Prevention of Restenosis with Tranilast and its Outcomes study (PRESTO), a double-blind, placebo-controlled study (n = 11,500), will test the efficacy of two doses (300 and 450 mg twice a day) of tranilast administered for 1 and 3 months compared with placebo. The primary objective is to compare the composite clinical event rate (death, myocardial infarction, or the need for ischemia-driven target vessel revascularization) after 9 months in patients treated with tranilast or placebo. Angiographic and intravascular ultrasound studies will be peformed in order to assess the effects of tranilast on angiographic restenosis and the volume of intimal hyperplastic tissue. If successful, tranilast will be the first drug to reduce angiographic and clinical restenosis.