Robotic-Assisted Percutaneous Coronary Intervention: Rationale, Implementation, Case Selection and Limitations of Current Technology.

Interventional cardiologists have witnessed an explosive growth in the field. A wide array of percutaneous procedures allow us to treat numerous cardiac conditions less invasively. However, the way we work has changed very little over the past decades. We continue to stand at the tableside for prolonged periods of time, exposing ourselves to the very real risks of radiation exposure as well as to the associated orthopedic injuries from radiation protection. The precision of our procedures is limited by the distance from the fluoroscopic images and, furthermore, patients are potentially at risk from operator fatigue caused by a physician standing at the table for prolonged periods while wearing cumbersome radiation protection gear. Robotic-assisted coronary intervention removes the operator from the radiation field and has been shown to markedly reduce operator exposure as well as allow for more precise positioning of balloons and stents. This technology holds great promise for making interventional procedures safer and more comfortable for the operators as well as reducing fatigue, potentially improving patient outcomes. Currently, we are in an 'early adopter' phase of this technology and this paper reviews the rationale, methodology, optimal case selection, and limitations of robotic-assisted coronary intervention.

Efficiency of endoscopy units can be improved with use of discrete event simulation modeling.

Background and study aims: The projected increased demand for health services obligates healthcare organizations to operate efficiently. Discrete event simulation (DES) is a modeling method that allows for optimization of systems through virtual testing of different configurations before implementation. The objective of this study was to identify strategies to improve the daily efficiencies of an endoscopy center with the use of DES. Methods: We built a DES model of a five procedure room endoscopy unit at a tertiary-care university medical center. After validating the baseline model, we tested alternate configurations to run the endoscopy suite and evaluated outcomes associated with each change. The main outcome measures included adequate number of preparation and recovery rooms, blocked inflow, delay times, blocked outflows, and patient cycle time. Results: Based on a sensitivity analysis, the adequate number of preparation rooms is eight and recovery rooms is nine for a five procedure room unit (total 3.4 preparation and recovery rooms per procedure room). Simple changes to procedure scheduling and patient arrival times led to a modest improvement in efficiency. Increasing the preparation/recovery rooms based on the sensitivity analysis led to significant improvements in efficiency. Conclusions: By applying tools such as DES, we can model changes in an environment with complex interactions and find ways to improve the medical care we provide. DES is applicable to any endoscopy unit and would be particularly valuable to those who are trying to improve on the efficiency of care and patient experience.

Critical limb ischemia: current approach and future directions.

Patients with critical limb ischemia (CLI) represent the highest risk patients with peripheral artery disease (PAD), with high rates of death, amputation, and other cardiovascular events. Previously, nonsurgical options for patients with CLI were limited. However, advances in endovascular techniques such as angiosome-based revascularization and technologies such as drug-eluting balloon and stent platforms have dramatically improved the therapeutic outlook. Additionally, advances in stem cell-based therapy and angiogenic factors show promise as adjuvant medical therapy.

Utility of daily troponin orders for identifying acute myocardial infarction patients for quality improvement.

BACKGROUND: Previous studies have demonstrated low rates of adherence to American College of Cardiology (ACC) and American Heart Association (AHA) guidelines for acute myocardial infarction (AMI). Quality improvement projects increase compliance with recommended therapies, but identification of AMI patients is a major challenge. OBJECTIVE: To determine the utility of a daily troponin list in identifying AMI patients for a quality improvement initiative to increase compliance with ACC/AHA-recommended therapies. DESIGN: Quality improvement initiative. METHODS AND RESULTS: During a 3-month period, the charts of patients with elevated troponin levels were screened for a diagnosis of AMI. For those patients with AMI, a clinical reminder about ACC/AHA-recommended therapies was placed in the chart. Nearly half (46%) of our hospital population had a troponin level measured during their clinical course. Of these, 26% had elevated troponin levels and 5% had AMI. All patients with AMI were identified using the daily troponin list with a sensitivity of 100% and a specificity of 78.4%. The daily troponin list captured more AMI patients than the admitting diagnosis. Use of the daily troponin list and targeted clinical reminders was associated with maintenance of a high (>95%) compliance with recommended therapies. CONCLUSIONS: A daily list of inpatients with a positive troponin identified all patients with AMI. Targeted reminders to clinicians regarding ACC/AHA-recommended therapies for AMI were associated with consistent adherence to guideline-recommended therapies.

Primary percutaneous coronary intervention in acute myocardial infarction.

Primary percutaneous coronary intervention (PCI) has emerged as the preferred therapy for acute ST-segment elevation myocardial infarction (STEMI), as multiple randomized clinical trials and pooled analyses have shown improved clinical outcomes compared with medical reperfusion. Unfortunately, medical centers with 24-hour PCI capability are concentrated in urban areas, relegating many patients in the United States to inferior medical reperfusion. Ongoing substantial research efforts are directed at optimizing mechanical reperfusion, including refinements in adjuvant medical therapy and the use of drug-eluting stents in the catheterization laboratory. Research efforts are also focusing on the implementation of streamlined transfer systems from community centers to tertiary care centers, akin to systems used in the trauma model. Furthermore, experience with the performance of primary PCI at community centers without onsite surgical backup is growing. This article summarizes data regarding the current state, challenges, and future directions of primary PCI for STEMI, emphasizing adherence to current American College of Cardiology/American Heart Association guidelines.

Peripheral arterial disease: an overview of endovascular therapies and contemporary treatment strategies.

Even in the absence of symptoms, peripheral arterial disease carries with it a significant risk of morbidity and mortality; thus, screening with the use of the ankle-brachial index is important in identifying patients at risk. Endovascular therapy in the lower extremities is continually evolving for treatment of patients with claudication symptoms or limb-threatening ischemia. Alternative treatments such as cryotherapy and the use of laser-assisted angioplasty hold much promise but need further investigation. In the case of renal artery stenosis and resulting hypertension, supportive clinical evidence is limited for renal revascularization despite the rationale for reducing cardiovascular risk. The current standard of care for significant carotid artery stenosis can include carotid stenting and carotid endarterectomy, but medical therapy may have a role also.

Low-molecular-weight heparin compared with unfractionated heparin for patients with non-ST-segment elevation acute coronary syndromes treated with glycoprotein IIb/IIIa inhibitors: results from the CRUSADE initiative.

BACKGROUND: Both heparin and glycoprotein (GP) IIb/IIIa inhibitor therapy and early invasive management strategies are recommended by the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for the treatment of patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS). However, controversy exists about which form of heparin-unfractionated (UF) or low-molecular-weight (LMW)-is preferable. We sought to compare the efficacy and safety of these treatment strategies in a large contemporary population of patients with NSTE ACS. METHODS: Using data from the CRUSADE Initiative, we evaluated LMWH and UFH in high-risk NSTE ACS patients (positive cardiac markers and/or ischemic ST-segment changes) who had received early (< 24 hours) GP IIb/IIIa inhibitor therapy and underwent early invasive management. In-hospital outcomes were compared among treatment groups. RESULTS: From a total of 11,358 patients treated at 407 hospitals in the US from January 2002-June 2003, 6881 (60.6%) received UFH and 4477 (39.4%) received LMWH. Patients treated with UFH were more often admitted to a cardiology inpatient service (73.6% vs. 65.5%, P < 0.0001) and more frequently underwent diagnostic catheterization (91.8% vs. 85.9%, P < 0.0001) and percutaneous coronary intervention (PCI) (69.7% vs. 56.9%, P < 0.0001) than patients treated with LMWH. The point estimate of the adjusted risk of in-hospital death or reinfarction was slightly lower among patients treated with LMWH (odds ratio [OR] 0.81, 95% confidence interval [CI] 0.67-0.99) and the risk of red blood cell transfusion was similar (OR 1.01, 95% CI 0.89-1.15). Among patients who underwent PCI within 48 hours, adjusted rates of death (OR 1.14, 95% CI 0.71-1.85), death or reinfarction (OR 0.93, 0.67-1.31), and transfusion (OR 1.16, 0.89-1.50) were similar. Patients who underwent PCI more than 48 hours into hospitalization had reduced rates of death (OR 0.64, 0.46-0.88), death or reinfarction (OR 0.57, 0.44-0.73), and transfusion (OR 0.66, 0.52-0.84). CONCLUSIONS: In routine clinical practice, patients treated with GP IIb/IIIa inhibitors have slightly improved outcomes and similar bleeding risks with LMWH than with UFH. These findings are consistent with current ACC/AHA guidelines but raise important questions about the safety and effectiveness of antithrombotic therapy in real-world clinical practice. Using data from the CRUSADE Initiative, we evaluated low-molecular-weight heparin (LMWH) and unfractionated heparin (UFH) in high-risk patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS) who received early (<24 hours) glycoprotein (GP) IIb/IIIa inhibitors and early invasive management. In-hospital outcomes were compared among treatment groups. LMWH was associated with slightly improved clinical outcomes and similar rates of transfusion compared with UFH. Our results support the current ACC/AHA guidelines recommendations but raise concerns about the safety and efficacy of UFH in the setting of background use of upstream GP IIb/IIIa inhibitors for patients with NSTE ACS in routine clinical practice.

Inhibition of Factor Xa : a potential target for the development of new anticoagulants.

Anticoagulant therapy plays an important role in the prevention and treatment of pathologic arterial and venous thrombosis. There is increasing enthusiasm in the inhibition of Factor Xa as a target to achieve therapeutic anticoagulation because of its central and 'upstream' position in the coagulation process. The indirect, selective, parenteral Factor Xa inhibitor fondaparinux sodium (synthetic pentasaccharide) has been studied extensively in the prevention and treatment of venous thromboembolism. In an overview of four studies in patients undergoing major orthopedic surgery, fondaparinux sodium was associated with a 55% reduction in recurrent thromboembolism, albeit with a modest increase in bleeding. Preliminary results from phase II studies of fondaparinux sodium in patients with ST-elevation and non-ST-elevation acute coronary syndromes have been promising and have led to the initiation of two large phase III trials, which are currently underway. Idraparinux sodium, a long-acting synthetic pentasaccharide, is currently being investigated as a once-weekly alternative to other long-term anticoagulants. DX-9065a and razaxaban are two of many direct selective Factor Xa inhibitors currently in development. DX-9065a has been studied in phase II trials in patients undergoing percutaneous coronary intervention and in those with non-ST-elevation acute coronary syndromes. Razaxaban has been studied in a phase II trial in patients who have undergone orthopedic surgery. Data from these trials, although preliminary and based on small numbers of patients, suggest that direct selective Factor Xa inhibition may provide effective anticoagulation, perhaps without excessive bleeding. Inhibition of Factor Xa is a promising target for the prevention and treatment of thrombosis in both the venous and arterial circulation. Ongoing investigation with numerous oral and parenteral inhibitors of Factor Xa will establish the potential of Factor Xa as a target for therapeutic anticoagulation.

Association between duration of tirofiban therapy before percutaneous intervention and tissue level perfusion (a TACTICS-TIMI 18 substudy).

In the setting of acute coronary syndromes, thrombotic embolization and activation of platelets with release of vasoconstrictors into the downstream microvasculature may occur before cardiac catheterization. In the Treat Angina with tirofiban and determine Cost of Therapy with an Invasive or Conservative Strategy-Thrombolysis In Myocardial Infarction 18 (TACTICS-TIMI 18) trial angiographic substudy, a shorter duration of tirofiban infusion before percutaneous coronary intervention was associated with impaired myocardial perfusion before and after intervention.

Rationale and strategies for implementing community-based transfer protocols for primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction.

The focus for the initial approach to the treatment of acute ST-segment elevation myocardial infarction (STEMI) has shifted toward extending the benefits of mechanical reperfusion with primary percutaneous coronary intervention (PCI) to patients who present to community hospitals that have no interventional capabilities. Several randomized clinical trials have shown that transferring STEMI patients to tertiary centers for primary PCI leads to better outcomes than when fibrinolytic therapy is administered at community hospitals. Furthermore, potent pharmacologic reperfusion regimens that enhance early reperfusion of the infarct vessel before primary PCI may enhance the positive result of the transfer approach. Despite these promising findings, several obstacles have hindered the adoption of patient-transfer strategies in the U.S., including greater distances between community and tertiary hospitals, a lack of integrated emergency medical services, and the medical community's limited experience with centralized acute myocardial infarction (AMI) care networks. Nonetheless, the implementation of system-wide changes in the care of STEMI patients analogous to the creation of trauma networks could facilitate the creation and ongoing evaluation of dedicated patient transfer strategies and better early invasive care in the U.S. Within this context, a systematic, stepwise approach to the creation of AMI care networks and to the development of standard nomenclature and performance indicators is necessary to guide quality assurance monitoring and future research efforts as the care of STEMI patients is redefined. Consequently, this current evolution of reperfusion strategies has the potential to further reduce morbidity and mortality for patients presenting with STEMI.