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Biomedical subjects

Peter C Block

Publications and source records attributed to Peter C Block.

At least 19 recordsLinked to original sources

Prevention of contrast induced nephropathy: recommendations for the high risk patient undergoing cardiovascular procedures.

Contrast induced nephropathy (CIN) is the third leading cause of hospital acquired renal failure and is associated with significant morbidity and mortality. Chronic kidney disease is the primary predisposing factor for CIN. As estimated glomerular filtration rate<60 ml/1.73 m2 represents significant renal dysfunction and defines patients at high risk. Modifiable risk factors for CIN include hydration status, the type and amount of contrast, use of concomitant nephrotoxic agents and recent contrast administration. The cornerstone of CIN prevention, in both the high and low risk patients, is adequate parenteral volume repletion. In the patient at increased risk for CIN it is often appropriate to withhold potentially nephrotoxic medications, and consider the use of n-acetylcysteine. In patients at increased risk for CIN the use of low or iso-osomolar contrast agents should be utilized and strategies employed to minimize contrast volume. In these patients serum creatinine should be obtained forty-eight hours post procedure and it is often appropriate to continue withholding medications such as metformin or non steroidal anti-inflammatories until renal function returns to normal.

Contrast Media↗

Integrated coronary revascularization with drug-eluting stents: immediate and seven-month outcome.

OBJECTIVE: We sought to demonstrate the safety and feasibility of an integrated coronary revascularization strategy that combines minimally invasive left internal thoracic artery to left anterior descending coronary artery anastomosis with drug-eluting stent implantation to non-left anterior descending coronary artery lesions. METHODS: Over 18 months, 47 consecutive patients with multivessel coronary artery disease underwent thoracoscopic harvesting of the left internal thoracic artery to graft the left anterior descending coronary artery. Anastomoses were constructed by hand, off-pump, and under direct vision through a 4-cm non-rib-spreading, muscle-sparing chest incision. Non-left anterior descending coronary artery lesions were then treated percutaneously using sirolimus- or paclitaxel-eluting stents. Angiographic follow-up was performed in all patients. RESULTS: Within the first 90 days of hospitalizations, there were no deaths, myocardial infarctions, neurologic events, or wound complications. Forty patients underwent left internal thoracic artery to left anterior descending coronary artery grafting, and 7 patients underwent left internal thoracic artery to left anterior descending coronary artery/diagonal sequential grafting for a total of 54 anastomoses. Angiographic patency scores were FitzGibbon A 96.2% (52/54) and FitzGibbon A + B 100% (54/54). A total of 65 drug-eluting stents were implanted in 61 non-left anterior descending coronary artery coronary lesions of which 49.1% (30/61) were type B2 or C lesions, including 5 left main lesions. Diabetes was present in 53.2% of patients (25/47). At a mean follow-up time of 7.0 +/- 4.8 months, the target lesion or vessel repeat revascularization rate was 6.6% (4/61) for drug-eluting stents and 1.9% (1/54) for left internal thoracic artery to left anterior descending coronary artery grafting. One anastomosis required balloon dilation, but no patients have required repeat coronary artery bypass grafting. CONCLUSIONS: Integrated coronary revascularization using drug-eluting stents is feasible and safe. There are sufficient data to justify a randomized comparison of integrated coronary revascularization with standard coronary artery bypass grafting.

Adult↗

Infection control guidelines for the cardiac catheterization laboratory: society guidelines revisited.

In the early years of diagnostic cardiac catheterization, strict sterile precautions were required for cutdown procedures. Thirteen years ago, when the original guidelines were written, the brachial arteriotomy was still frequently utilized, femoral closure devices were uncommon, "implantables," such as intracoronary stents and PFO/ASD closure devices, were in their infancy, and percutaneous valve replacement was not a consideration. In 2005, the cardiac catheterization laboratory is a complex interventional suite with percutaneous access routine and device implantation standard. Despite frequent device implantation, strict sterile precautions are often not observed. Reasons for this include a decline in brachial artery cutdown, limited postprocedure follow-up with few reported infections, limited use of hats and masks in televised cases, and lack of current guidelines. Proper sterile technique has the potential to decrease the patient infection rate. Hand washing remains the most important procedure for preventing infections. Caps, masks, gowns, and gloves help to protect the patient by maintaining a sterile field. Protection of personnel may be accomplished by proper gowning, gloving, and eye wear, disposal of contaminated equipment, and prevention and care of puncture wounds and lacerations. With the potential for acquired disease from blood-borne pathogens, the need for protective measures is as essential in the cardiac catheterization laboratory as is the standard Universal Precautions, which are applied throughout the hospital. All personnel should strongly consider vaccination for hepatitis B. Maintenance of the cardiac catheterization laboratory environment includes appropriate cleaning, limitation of traffic, and adequate ventilation. In an SCAI survey, members recommended an update on guidelines for infection control in the cardiac catheterization laboratory. The following revision of the original 1992 guidelines is written specifically to address the increased utilization of the catheterization laboratory as an interventional suite with device implantation. In this update, infection protection is divided into sections on the patient, the laboratory personnel, and the laboratory environment. Additionally, specific CDC recommendation sections highlight recommendations from other published guidelines.

Antibiotic Prophylaxis↗

Percutaneous left atrial appendage closure in a patient with atrial fibrillation.

BACKGROUND: A 73-year-old woman presented with a history of persistent atrial fibrillation, which had lasted more than five years. She also had a remote history of transient ischemic attack and had received warfarin therapy. The international normalized ratio had been carefully maintained at slightly subtherapeutic levels because of recurrent gastrointestinal bleeding, which was severe enough to require frequent blood transfusions. With colonoscopy, the source of bleeding was localized to multiple arterial-venous malformations. The patient underwent catheter ablation of the atrioventricular junction and received a single chamber pacemaker. Two years later, she received a dual chamber pacemaker followed by cardioversion to restore a sinus rhythm. Following brief cardioversion, her symptoms of atrial fibrillation returned after two days. INVESTIGATIONS: Transesophageal echocardiography, pacemaker interrogation. DIAGNOSIS: Persistent atrial fibrillation, gastrointestinal bleeding requiring transfusion. MANAGEMENT: Percutaneous left atrial appendage occlusion, antiplatelet therapy.

Aged↗

Percutaneous transcatheter repair for mitral regurgitation.

Percutaneous mitral valve repair for patients with mitral regurgitation is emerging as an exciting new area in interventional cardiology. Because of the complex etiologies of mitral regurgitation, multiple technologies are being tested in preclinical and clinical settings to evaluate their efficacy and safety. Direct percutaneous repair of the mitral valve is undergoing Phase II and Phase I trials using the Evalve mitral clip and Edwards mitral suture devices, respectively. Devices placed in the coronary sinus might be applicable for specific patient populations where the mitral annulus and coronary sinus have favorable anatomic relationships. Other devices employ intra-atrial or intra-ventricular approaches to the mitral annulus to move the posterior annulus forward and thereby improve mitral valve coaptation. How many of these new techniques will ultimately be successful for clinical use will depend on the results of ongoing clinical trials.

Cardiac Surgical Procedures↗

Percutaneous mitral valve repair using the edge-to-edge technique: six-month results of the EVEREST Phase I Clinical Trial.

OBJECTIVES: This study sought to evaluate the clinical results of a percutaneous approach to mitral valve repair for mitral regurgitation (MR). BACKGROUND: A surgical technique approximating the middle scallops of the mitral leaflets to create a double orifice with improved leaflet coaptation was introduced in the early 1990s. Recently, a percutaneous method to create the same type of repair was developed. A trans-septal approach was used to deliver a clip device that grasps the mitral leaflet edges to create the double orifice. METHODS: General anesthesia, fluoroscopy, and echocardiographic guidance are used. A 24-F guide is positioned in the left atrium. The clip is centered over the mitral orifice, passed into the left ventricle, and pulled back to grasp the mitral leaflets. After verification that MR is reduced, the clip is released. RESULTS: Twenty-seven patients had six-month follow-up. Clips were implanted in 24 patients. There were no procedural complications and four 30-day major adverse events: partial clip detachment in three patients, who underwent elective valve surgery, and one patient with post-procedure stroke that resolved at one month. Three additional patients had surgery for unresolved MR, leaving 18 patients free from surgery. In 13 of 14 patients with reduction of MR to < or =2+ after one month, the reduction was maintained at six months. CONCLUSIONS: Percutaneous edge-to-edge mitral valve repair can be performed safely and a reduction in MR can be achieved in a significant proportion of patients to six months. Patients who required subsequent surgery had elective mitral valve repair or intended replacement.

Aged↗

Percutaneous left atrial appendage transcatheter occlusion (PLAATO system) to prevent stroke in high-risk patients with non-rheumatic atrial fibrillation: results from the international multi-center feasibility trials.

OBJECTIVES: These studies were conducted to evaluate the feasibility of percutaneous left atrial appendage (LAA) occlusion using the PLAATO system (ev3 Inc., Plymouth, Minnesota). BACKGROUND: Patients with atrial fibrillation (AF) have a five-fold increased risk for stroke. Other studies have shown that more than 90% of atrial thrombi in patients with non-rheumatic AF originate in the LAA. Transvenous closure of the LAA is a new approach in preventing embolism in these patients. METHODS: Within two prospective, multi-center trials, LAA occlusion was attempted in 111 patients (age 71 +/- 9 years). All patients had a contraindication for anticoagulation therapy and at least one additional risk factor for stroke. The primary end point was incidence of major adverse events (MAEs), a composite of stroke, cardiac or neurological death, myocardial infarction, and requirement for procedure-related cardiovascular surgery within the first month. RESULTS: Implantation was successful in 108 of 111 patients (97.3%, 95% confidence interval [CI] 92.3% to 99.4%) who underwent 113 procedures. One patient (0.9%, 95% CI 0.02% to 4.9%) experienced two MAEs within the first 30 days: need for cardiovascular surgery and in-hospital neurological death. Three other patients underwent in-hospital pericardiocentesis due to a hemopericardium. Average follow-up was 9.8 months. Two patients experienced stroke. No migration or mobile thrombus was noted on transesophageal echocardiogram at one and six months after device implantation. CONCLUSIONS: Closing the LAA using the PLAATO system is feasible and can be performed at acceptable risk. It may become an alternative in patients with AF and a contraindication for lifelong anticoagulation treatment.

Aged↗

Mortality after emergent percutaneous coronary intervention in cardiogenic shock secondary to acute myocardial infarction and usefulness of a mortality prediction model.

Although percutaneous coronary intervention (PCI) in the setting of cardiogenic shock has a high in-hospital mortality rate, it has been shown to decrease the mortality rate in certain subgroups. The identity and relative importance of variables that are predictive of in-hospital mortality rate after PCI for cardiogenic shock are uncertain. Accordingly, we examined data of >300,000 patients in the American College of Cardiology-National Cardiovascular Data Registry (ACC-NCDR) that were collected from 1998 to 2002 and evaluated the outcomes in 483 consecutive patients who underwent emergency PCI for cardiogenic shock. Patients' mean age was 65 +/- 13 years, with men predominating (61%). All underwent emergency/salvage PCI in the setting of cardiogenic shock after acute myocardial infarction. Mean left ventricular ejection fraction was 30 +/- 16%. Stents were placed in 64% of patients, and thrombolytic agents were administered in 26%. Although PCI was angiographically successful in 79% of patients, the in-hospital mortality rate was 59.4%. Length of stay after PCI was 7.2 +/- 8 days. Logistic regression using all available variables identified 6 multivariate predictors of death: age (odds ratio [OR] 2.34, 95% confidence interval [CI] 1.68 to 3.28, p <0.001) for each 10-year increment, female gender (OR 1.55, 95% CI 1.00 to 2.41, p <0.001), baseline renal insufficiency (creatinine >2.0 mg/dl; OR 4.69, 95% CI 1.96 to 11.23, p <0.001), total occlusion in the left anterior descending artery (OR 1.99, 95% confidence interval 1.28 to 3.09, p <0.01), no stent used (OR 2.55, 95% CI 1.63 to 3.96, p <0.01), and no glycoprotein IIb/IIIa inhibitor used during PCI (OR 1.96, 95% CI 1.30 to 2.98, p <0.01). In a second analysis using only variables known to the clinician at the time of initial presentation, gender, age, renal insufficiency, and total occlusion of the left anterior descending coronary artery were significant. In conclusion, analysis of patients from the ACC-NCDR who underwent emergency PCI for acute myocardial infarction in the presence of cardiogenic shock shows an in-hospital mortality rate of approximately 60% when PCI is attempted.

Age Factors↗

Percutaneous approaches to valvular heart disease.

Percutaneous endovascular therapy has now become a reality. From early balloon valvotomy for valvular stenosis, technologies have been developed that allow percutaneous replacement of pulmonic and aortic valves and repair of regurgitant mitral valves in selected patients. Following extensive investigations in animals, early clinical reports have shown successes in selected patients. As criteria for patient selection and clinical safety and efficacy trials progress, the role of these new technologies in patient care strategy will become better understood.

Adolescent↗

Surgical revision after percutaneous mitral valve repair with a clip: initial multicenter experience.

PURPOSE: Almost 50,000 mitral valve operations are performed annually in the United States, with an increasing number of repairs. Recently, a percutaneous mitral valve repair option that achieves edge-to-edge approximation with a clip has been described in patients with mitral regurgitation. DESCRIPTION: We describe 6 patients from three centers with mitral regurgitation after percutaneous repair who underwent reintervention. During open surgical revision, the clips were uneventfully removed in all patients with no limitation in surgical options. Five patients underwent repair and 1 underwent replacement. EVALUATION: After surgical revision, mitral regurgitation was significantly decreased, and all but 1 patient underwent uneventful recovery. One patient developed ilio-femoral deep venous thrombosis that was treated successfully with anticoagulation. CONCLUSIONS: Preserving standard of care options is critical with any evolving technology in the event of initial treatment failure. Standard surgical options were preserved in all of the patients who underwent percutaneous mitral valve edge-to-edge repair. Furthermore, a thorough understanding of the clip design, in particular its unlocking mechanism, is essential and facilitates surgical clip removal.

Adult↗

Atrial septal abnormalities and cryptogenic stroke: a paradoxical science.

Patent foramen ovale and/or atrial septal aneurysm occur in up to 20% of the general population, and have been linked to cryptogenic ischemic strokes in younger individuals. The pathophysiologic basis of this association remains unclear, with growing evidence suggesting a role for thrombosis and embolization. Aspirin and warfarin constitute the current mainstay of medical therapy, with a variety of secondary prevention studies assessing their impact on stroke recurrence. To date, the quality of published data preclude the development of strict recommendations, but a number of suggestions can be derived from available literature. Patients with isolated patent foramen ovale or atrial septal aneurysm and a first ischemic stroke respond well to either aspirin or warfarin therapy. On the other hand, oral anticoagulation seems to be the preferred medical therapy in higher-risk patients with both patent foramen ovale and atrial septal aneurysm or those with multiple strokes on aspirin. Percutaneous or surgical patent foramen ovale closures have been proposed as alternative therapies and seem effective in reducing stroke recurrence. In the absence of randomized, controlled trials comparing medical and invasive approaches, the adoption of a particular therapy should take into consideration the individual's preference, clinical presentation, risk profile, lifestyle, and the expertise of the local interventional and surgical teams.

Anticoagulants↗