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Biomedical subjects

Keith B Allen

Publications and source records attributed to Keith B Allen.

11 recordsLinked to original sources
PubMed2006

Transmyocardial laser revascularization as an adjunct to coronary artery bypass grafting.

Many patients with angina related to coronary artery disease respond to medical management or can be completely revascularized using available percutaneous coronary interventions or coronary artery bypass grafting (CABG). There is evidence, however, to indicate that up to 25% of patients are incompletely revascularized following CABG and that incomplete revascularization is a significant independent predictor of early and late mortality and adverse events. Transmyocardial revascularization (TMR) is a surgical option for patients with debilitating angina due to coronary artery disease in areas of the heart not amenable to complete revascularization using conventional treatments. In randomized, 1-year controlled trials with long-term follow-up and in additional clinical experience, TMR performed adjunctively to CABG in patients who would be incompletely revascularized by CABG alone has yielded significantly improved clinical outcomes. Based on these published results, the Society of Thoracic Surgeons has issued a practice guideline recommending adjunctive TMR in this difficult patient group.

Angina Pectoris↗
PubMed2006

Holmium:YAG laser system for transmyocardial revascularization.

Transmyocardial revascularization, using the US FDA-approved holmium: yttrium-aluminum-garnet (Ho:YAG) laser system, is a surgical option for patients with debilitating angina caused by diffuse coronary artery disease in areas of the heart not amenable to complete revascularization using conventional treatments. Increased utilization of this therapy is warranted, in parallel with continuing research into therapeutic or cell-based methods for enhancing the clinically relevant, positive outcomes. This article will review the clinical science surrounding Ho:YAG transmyocardial revascularization with an emphasis on the randomized controlled trials performed in these patient groups.

Angina Pectoris↗
PubMed2004

The Society of Thoracic Surgeons practice guideline series: transmyocardial laser revascularization.

BACKGROUND: Patients with chronic severe angina refractory to medical therapy who cannot be completely revascularized with either percutaneous catheter intervention or coronary artery bypass graft surgery present clinical challenges. Transmyocardial laser revascularization, either as sole therapy or as an adjunct to coronary artery bypass graft surgery, may be appropriate for some of these patients. Although transmyocardial revascularization has consistently been demonstrated as an efficacious means of relieving angina, the mechanism of its effects are still debated, and criteria for the selection of patients for this novel therapy have not been adequately defined. METHODS: We reviewed the available evidence to allow us to make recommendations for the appropriate therapeutic applications of transmyocardial revascularization following the format of the American Heart Association and the American College of Cardiology guidelines for diagnostic and therapeutic procedures. Our recommendations were classified as class I, IIA, IIB, or III. For each recommendation we defined the level of supporting evidence as A, B, or C. RESULTS: We identified class I indications for transmyocardial revascularization as sole therapy and class IIA indications for transmyocardial revascularization as an adjunct to coronary artery bypass graft surgery with levels of evidence A and B, respectively. CONCLUSIONS: Transmyocardial laser revascularization may be an acceptable form of therapy for selected patients: as sole therapy for a subset of patients with refractory angina and as an adjunct to coronary artery bypass graft surgery for a subset of patients with angina who cannot be completely revascularized surgically.

Angina Pectoris↗
PubMed2004

Transmyocardial revascularization: 5-year follow-up of a prospective, randomized multicenter trial.

BACKGROUND: In prospective randomized trials at 1 year, transmyocardial revascularization (TMR) provided superior relief of angina, decreased rehospitalizations, and improved exercise times. We evaluated 5-year mortality and angina class in "no-option" patients with diffuse coronary artery disease randomized to TMR or continued medical management. METHODS: Two hundred twelve patients with refractory class IV angina who were not candidates for conventional therapy were randomized to receive holmium:yttrium-aluminum-garnet TMR (n = 100) or continued medical management (n = 112) at nine centers. Follow-up included all-cause mortality along with angina class assessment by blinded evaluators. Mean follow-up was 5.7 +/- 0.8 years. RESULTS: Mean angina scores for TMR patients were 4.0 +/- 0.0 at baseline, 1.5 +/- 1.4 at 1 year, and 1.2 +/- 1.1 at a mean of 5 years (p < 0.001). After an average of 5 years, a significantly greater proportion of TMR than medical management patients experienced two or more class improvement in angina (88% versus 44%; p < 0.001). Kaplan-Meier intention-to-treat survival at 5 years was 65% versus 52% (TMR versus medical management; p = 0.05). Cumulative hazard curves demonstrated a significantly reduced risk of late death for TMR patients; average annual mortality beyond 1 year was 8% versus 13% (TMR versus medical management; p = 0.03). CONCLUSIONS: Five-year follow-up of prospectively randomized, no-option class IV angina patients demonstrated significantly increased Kaplan-Meier survival in patients randomized to TMR. The significant angina relief observed 12 months after sole therapy TMR was sustained long term and continued to be superior to that observed for patients maintained on continued medical management alone.

Angina Pectoris↗
PubMed2004

Adjunctive transmyocardial revascularization: five-year follow-up of a prospective, randomized trial.

BACKGROUND: In a prospective, randomized trial involving 263 patients who would be incompletely revascularized by coronary artery bypass grafting (CABG) alone, CABG plus transmyocardial revascularization (CABG/TMR) provided an early mortality benefit with similar angina relief compared with CABG alone at 1 year. We evaluated the long-term outcome of patients randomized to CABG/TMR or CABG alone. METHODS: Thirteen centers that enrolled 83% (218/263) of the patients in the original trial participated in this longitudinal study. Between 1996 and 1998, these centers randomized 218 patients who would be incompletely revascularized by CABG alone because of diffusely diseased target vessels to either holmium:yttrium-aluminum-garnet (holmium:YAG) CABG/TMR (n = 110) or CABG alone (n = 108). Baseline demographics and operative characteristics were similar between groups. Follow-up (mean 5.0 +/- 1.7 years) included survival and blinded angina class assessment. RESULTS: At this 5-year follow-up both groups experienced significant angina improvement from baseline, however, the CABG/TMR group had a lower mean angina score (0.4 +/- 0.7 vs 0.7 +/- 1.1, p = 0.05), a significantly lower proportion of patients with severe angina (class III/IV: 0% [0/68] vs 10% [6/60], p = 0.009), and a trend towards greater number of angina-free patients (78% [53/68] vs 63% [38/60], p = 0.08), compared with CABG alone patients. Kaplan-Meier survival at 6 years was similar between CABG/TMR and CABG alone patients (76% vs 80%, p = 0.90). CONCLUSIONS: Five-year follow-up of prospectively randomized patients who would be incompletely revascularized because of diffuse coronary artery disease indicates that the addition of TMR to conventional CABG provides superior angina relief compared to CABG alone.

Aged↗
PubMed2003

Evolving revascularization approaches for myocardial ischemia.

Stable angina pectoris secondary to ischemic heart disease is a common and disabling condition. Medical therapy aims to relieve symptoms, improve exercise capacity, and decrease cardiac events by reducing myocardial oxygen demand or improving coronary blood supply to the ischemic myocardium. If medical treatment is inadequate, invasive revascularization procedures to improve coronary perfusion are considered. Percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass graft (CABG) surgery are well-established and widely used myocardial revascularization techniques. Recent advances in PTCA have attempted to address the problem of restenosis, initially through the deployment of bare metal intracoronary stents and, more recently, with drug-eluting stents. Developments in CABG have focused on reducing the invasiveness of the procedure and minimizing the incidence of serious complications. Refinements include the use of mechanical stabilizers, endoscopic harvesting of conduit vessels, robotic telemanipulation systems, and fully automated anastomotic devices. Surgical laser transmyocardial revascularization and therapeutic angiogenesis represent newer approaches to coronary revascularization. Therapeutic angiogenesis aims to deliver an angiogenic growth factor or cytokine to the myocardium to stimulate collateral blood vessel growth throughout the ischemic tissue. The angiogenic factor may be administered as a recombinant protein or as a transgene within a plasmid or gene-transfer vector. Ongoing angiogenic gene therapy clinical trials are evaluating which factors, vectors, and delivery techniques hold the greatest promise for management of patients with chronic stable angina.

Angiogenesis Inducing Agents↗
PubMed2003

Emboli capture using the Embol-X intraaortic filter in cardiac surgery: a multicentered randomized trial of 1,289 patients.

BACKGROUND: Particulate emboli are thought to play a significant role in the development of cardiac surgical complications. Intraaortic filtration of particulate emboli may reduce the burden of this morbidity in cardiac patients. METHODS: A multiinstitutional randomized trial was designed and enrolled 1,289 patients at 22 centers. Six hundred forty-five patients were assigned to the treatment arm and received the Embol-X intraaortic filter, whereas 644 patients were assigned to the control arm. The endpoints examined were mortality, stroke, transient ischemic attack, renal insufficiency/failure, myocardial infarction, gastrointestinal complications, and limb-threatening ischemia. All filters were examined for histologic evidence of particulate emboli. RESULTS: Particulate emboli were identified in 598 (96.8%) of 618 filters successfully deployed. Composite event rates for the clinical endpoints were similar in both the filtered and nonfiltered arm (110/645 = 17% vs 122/644 = 19%, respectively). Individual event rates were also similar in both arms. A post hoc comparison of patients with moderate or greater preoperative risk scores demonstrated event reduction favoring the filtered group for renal complications (17/124 = 14% vs 28/117 = 24%, p = 0.04) and for the composite endpoint (30/124 = 24% vs 42/117 = 36%, p = 0.047). No clinically evident complications attributed to the use of the filter were identified. CONCLUSIONS: The use of the Embol-X intraaortic filter is both safe and effective, as demonstrated by the emboli capture rate of 97%. In addition, post hoc analysis indicates a reduction in postoperative renal complications for patients with moderate or greater preoperative risk. Further study of high-risk patients is warranted.

Aged↗
PubMed2003

Influence of endoscopic versus traditional saphenectomy on event-free survival: five-year follow-up of a prospective randomized trial.

BACKGROUND: Endoscopic harvesting of the greater saphenous vein is increasingly used during cardiac surgery to improve patient satisfaction and reduce the wound complications associated with traditional open techniques. Although histologic studies suggest no significant difference in vein quality between these two techniques, long-term follow-up is lacking to address whether graft patency and event-free survival are influenced by the harvest method. METHODS: A total of 112 isolated coronary artery bypass patients were prospectively randomized to have veins harvested using either an endoscopic (n = 54) or traditional (n = 58) technique. Groups were demographically similar with regard to preoperative risk stratification and coronary procedures performed. Event-free survival (freedom from death, myocardial infarction, or recurrent angina) and use of outpatient resources for resolution of wound complications were determined. Follow-up was 100% at 5 years. RESULTS: Five-year actual event-free survival was similar in patients with endoscopic versus traditionally harvested v e ins (75% versus 74%, P =.85). The number of outpatient office visits required to manage each wound complication to complete resolution was significantly less following endoscopic versus traditional vein harvest (1.5 versus 6 visits, P =.001). CONCLUSIONS: Wound complication management following endoscopic versus traditional vein harvest requires less resource utilization. Five-year follow-up of a prospective randomized trial demonstrates that use of endosco pic versus traditionally harvested saphenous veins does not influence event-free survival.

Angioscopy↗