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Lloyd W Klein

Publications and source records attributed to Lloyd W Klein.

At least 37 records · Page 2Linked to original sources
PubMed2005

Clinical implications and mechanisms of plaque rupture in the acute coronary syndromes.

Coronary atherosclerosis complicated by plaque rupture or disruption and thrombosis is primarily responsible for the development of acute coronary syndromes. Plaques with a large extracellular lipid-rich core, a thin fibrous cap due to reduced collagen content and smooth muscle density, and increased numbers of activated macrophages and mast cells appear to be vulnerable to rupture. Plaque disruption tends to occur at points at which the plaque surface is weakest and most vulnerable, which coincide with points at which stresses resulting from biomechanical and hemodynamic forces acting on plaques are concentrated. Reduced matrix synthesis as well as increased matrix degradation predisposes vulnerable plaques to rupture in response to extrinsic mechanical or hemodynamic stresses. Modification of endothelial dysfunction and reduction of vulnerability to plaque rupture and thrombosis may lead to plaque stabilization. These concepts have significant clinical implications that are just beginning to be explored and incorporated into clinical practice. This article reviews the mechanism of coronary atherosclerosis development and the pathophysiology of acute coronary syndromes to provide a framework for understanding how plaque passivation might be accomplished in clinical medicine.

Acute Disease↗
PubMed2004

Drug-eluting stent task force: final report and recommendations of the working committees on cost-effectiveness/economics, access to care, and medicolegal issues.

Coronary artery disease remains a major health problem worldwide. Since introduction of percutaneous transluminal coronary angioplasty and stents, much progress has been made. Percutaneous coronary intervention, however, has been limited by restenosis (repeat obstruction of arteries that have been previously treated. Introduction of drug-eluting stents (DESs) in April 2003 was a major breakthrough in preventing restenosis. In March 2003, The Society for Cardiovascular Angiography and Interventions (SCAI) published a position statement on the clinical implications of DESs, recommending an evidence-based adoption strategy. Subsequently, in May 2003, SCAI formed a multidisciplinary Drug Eluting Stent (DES) Task Force to address the significant nonclinical ramifications posed by DESs: medicolegal, financial, and access to care. The Task Force included representatives from physician societies, industry, academia, the reimbursement community, and health policy organizations. The resultant report presents analyses, options, and recommendations regarding those nonclinical issues based on the collective experience and knowledge of the Task Force members. The Task Force trusts that this report will be of value to the diverse constituencies involved with introduction of this important new technology.

Advisory Committees↗
PubMed2004

Occupational hazards of interventional cardiologists: prevalence of orthopedic health problems in contemporary practice.

Invasive cardiologists generally consider radiation to be the chief occupational hazard. Heavy leaded aprons worn to reduce this risk may be associated with orthopedic complications. This study was designed to characterize the prevalence of these occupational health problems. The Interventional Committee of the Society for Cardiac Angiography and Interventions (SCAI) sent to its Internet-registered members a Web-based survey. Inquiries included age, years of invasive practice, and diagnostic/interventional cases/year. Questions (yes/no) focused on orthopedic (spine, hips, knees, and ankles) and radiation-associated problems (cataracts and cancers). The survey was sent to over 1,600 members with 424 responses. Responders were on average busy and experienced, performing catheterization > 10 years in 62% of cases and > 20 years in 24% others. Average annual diagnostic-only case load was > 200/year in 72%, > 300/year in 43%, and > 500/year in 18% of responders. Reported annual interventional caseload was > 100/year in 83%, > 200/year in 37%, and > 300/year in 15% of operators. Orthopedic problems included spine problems in 42% of responders (of these, 70% were lumbosacral and 30% cervical). Hip, knee, or ankle problems were noted in 28% of operators. Spine problems were related to the annual procedural caseload and the number of years in practice. Over one-third reported spine problems had caused them to miss work. The results of the radiation queries were inconclusive. These results document that interventional cardiologists commonly suffer orthopedic disease, frequently leading to lost work days.

Adult↗
PubMed2004

SCAI statement on ad hoc versus the separate performance of diagnostic cardiac catheterization and coronary intervention.

Coronary intervention may be combined with diagnostic cardiac catheterization or performed separately. In the early years of angioplasty, performing these procedures separately was standard practice. Gradually, ad hoc intervention (performing diagnostic angiography and coronary intervention within the same session) has become more common, largely because of its convenience for patients and efficiency for physicians. However, the safety and potential cost savings of this approach remain uncertain. Criteria for the appropriate use of ad hoc intervention have not been established. Ad hoc intervention is reasonable for many, but not appropriate for all patients and should not be considered standard therapy. This document updates an earlier review of this topic and provides suggestions for the use of ad hoc intervention as a routine strategy.

Angioplasty, Balloon, Coronary↗
PubMed2004

Changes in coronary endothelial function predict progression of allograft vasculopathy after heart transplantation.

OBJECTIVE: Coronary endothelial dysfunction may be an early marker for cardiac allograft vasculopathy (CAV) in orthotopic heart transplant recipients. We used serial studies to evaluate changes in coronary endothelial function in patients with and without clinically evident CAV. BACKGROUND: In serial studies with intravascular ultrasound (IVUS) and Doppler flow wire measurements, we previously demonstrated that annual decrements in coronary endothelial function are associated with progressive intimal thickening. METHODS: We studied 45 patients annually, beginning at transplantation until pre-specified end-points (angiographic CAV or cardiac death) were reached. At each study, we measured coronary endothelial function using intracoronary infusions of adenosine, acetylcholine, and nitroglycerin. We simultaneously recorded IVUS images and Doppler velocities. RESULTS: Of the 45 patients studied, 9 reached end-points during the study (6 had CAV and 3 died). The mean annual change in area response to acetylcholine was -4.5% +/- 3.0% in patients who reached end-points and -0.9% +/- 1.5% in those who did not (p = 0.04). The mean annual decrement in flow response to acetylcholine was greater in patients who reached end-points (-31% +/- 11% vs -5% +/- 5%, p = 0.08). Responses to adenosine and nitroglycerin did not differ. CONCLUSIONS: When serial responses were evaluated, patients with end-points had more rapid decreases in endothelial function. The rate of disease progression may be more important than the absolute degree of intimal thickening in early CAV. These data implicate endothelial dysfunction in the development of clinically significant vasculopathy and suggest that serial studies of endothelial function may provide important prognostic information about the development of CAV after heart transplantation.

Blood Flow Velocity↗
PubMed2003

Evaluation of the American College of Cardiology/American Heart Association and the Society for Coronary Angiography and Interventions lesion classification system in the current "stent era" of coronary interventions (from the ACC-National Cardiovascular Data Registry).

In 1988 American College of Cardiology (ACC)/American Heart Association (AHA) Guidelines for Coronary Angioplasty proposed a lesion classification system to stratify lesions by difficulty and risk to better understand the outcomes of coronary interventions. It was a 3-level (A, B, and C) classification based on 11 lesion characteristics. A modification, dividing the intermediate B category into B1 and B2, is also in common use. Recently, a simplification of this classification was evaluated using the large Society for Cardiac Angiography and Interventions (SCAI) Registry (SCAI I = non-C/patent; SCAI II = C/patent; SCAI III = non-C/occluded; SCAI IV = C/occluded). The lesion classification systems were evaluated in 61,926 patients from the ACC National Cardiovascular Data Registry who underwent single-vessel percutaneous coronary intervention between January 1998 and September 2000. Stents were placed in 74.5% of patients. Logistic models for lesion success and complications were constructed and compared. The c statistic for success using the ACC/AHA original classification system was 0.69, 0.71 for the modified ACC/AHA system, and 0.75 for the SCAI classification. The range of complication and success rates was greater using the SCAI models, and the logistic models for success and complication were more robust for the SCAI system. Thus, in the large ACC-National Cardiovascular Data Registry, with a high percentage of stent usage, the simpler SCAI lesion classification provided better discrimination for success and complications than the more complex ACC/AHA lesion classification system-original or modified.

Angioplasty, Balloon, Coronary↗
PubMed2003

Management of patients undergoing percutaneous coronary revascularization.

While performance of percutaneous coronary intervention (PCI) remains the domain of specialized cardiologists, patients undergoing PCI are cared for by noninvasive cardiologists, internists, and primary care physicians. Therefore, patient care is optimized when the entire patient care team understands procedural risks and complications as well as optimum patient management before, during, and after PCI. Before PCI, patients with contrast dye allergies should be identified and pretreated with steroids and an H1-blocker. Hydration should be initiated and maintained before and after the procedure to minimize the risks for contrast nephropathy. Periprocedure, patients should be monitored clinically for evidence of ischemia. In patients with significant groin, flank, abdominal, or back pain, as well as those with decrease in hematocrit or unexplained hypotension, the diagnosis of groin or retroperitoneal hematoma should be considered and promptly evaluated. Groin tenderness, pulsatile mass, or bruit should prompt evaluation for possible femoral pseudoaneurysm or arteriovenous fistulae. After the procedure, all patients treated with coronary stents should receive aspirin plus clopidogrel. Patients who develop typical anginal symptoms between the 1st and 6th to 8th months after PCI are likely to have restenosis and can be evaluated by an imaging study or repeated catheterization.

Angioplasty, Balloon, Coronary↗
PubMed2003

Alternative therapeutic strategies for patients with severe end-stage coronary artery disease not amenable to conventional revascularization.

Although there have been remarkable advances in medical therapy, percutaneous coronary interventions, and coronary artery bypass graft surgery, complete revascularization remains a challenge given the more complex coronary artery disease prevalent in contemporary practice. The lack of donors for cardiac transplantation will fuel the search for effective alternative strategies for dealing with patients with severe ischemic heart disease not amenable to conventional revascularization techniques. Percutaneous laser revascularization clearly diminishes anginal symptoms; however, the blinded trials have provided conflicting results, with one study showing a definite decrease in angina and another suggesting that the placebo effect may play a major role in this modality. Similarly, surgical transmyocardial laser revascularization is limited by the lack of consistent improvement in objective measurements of ischemia and the potential confounding mechanisms of denervation and the placebo effect, and thus should be reserved for only the most highly selected patients. Although enhanced external counterpulsation is associated with an improvement in anginal symptoms and exercise tolerance, this modality is limited by its availability, tolerability, and rigid exclusion criteria. Of the alternative strategies available, therapeutic angiogenesis holds the most promise. However, the long-term results of ongoing randomized clinical trials require further scrutiny. Novel methods for vascular reconstruction are evolving techniques, but should be viewed currently as mainly experimental methods. The common goals of these new treatment options would be to reduce symptoms, decrease morbidity, and potentially improve mortality by reducing ischemia through favorably impacting myocardial oxygen supply and demand. The optimal management of patients with severe end-stage coronary artery disease not amenable to conventional revascularization techniques will continue to remain a challenge for the clinician and will be the main focus of basic cardiovascular research and clinical trials in the new millennium.

Angioplasty, Laser↗