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John G Webb

Publications and source records attributed to John G Webb.

At least 19 recordsLinked to original sources
PubMed2006

Six-month outcome of transapical transcatheter aortic valve implantation in the initial seven patients.

BACKGROUND: The current treatment of choice for symptomatic aortic stenosis is aortic valve replacement (AVR) with cardiopulmonary bypass (CPB), but AVR is associated with significant operative morbidity and mortality in elderly patients with multiple co-morbid conditions. We recently reported the first successful aortic valve implantation procedure (AVI) via a mini-thoracotomy and left ventricular apical puncture without cardiopulmonary bypass. We now report 6-month follow-up in our initial seven patients. METHODS: Seven patients (77+/-10 years old) with symptomatic aortic stenosis were deemed to be non-surgical candidates for AVR and not suitable for a transfemoral percutaneous heart valve implantation due to aorto-iliac disease. The predicted 30-day operative mortality was 31+/-23% according to logistic Euroscore. Patients underwent minimally invasive transapical AVI. With the guidance of fluoroscopy and transesophageal echocardiography, balloon predilation was followed by deployment of a 26mm Cribier-Edwardstrade mark valve (Edwards Lifesciences Inc., Irvine, CA) during rapid ventricular pacing to reduce forward flow and cardiac motion. RESULTS: Valve implantation was successful in all seven patients. There were no intra-procedural mortalities or complications. Thirty-day operative mortality was 14%. One patient died at day 12 due to pneumonia. Two patients died from non-cardiac diseases at day 51 and 85. The remaining four patients completed 6-month follow-up. The aortic valve area increased from 0.7+/-0.3 to 1.8+/-0.7 and 1.5+/-0.5cm(2) at 1 and 6 months, respectively. The mean transaortic gradient was reduced from 32+/-8 to 10+/-5 and 11+/-8mmHg at 1 and 6 months, respectively. Following AVI, none or trivial, mild, and moderate aortic regurgitation was observed in 4, 2, and 1 patients, respectively. There were no valve-related complications during the follow-up. CONCLUSION: Aortic valve implantation can successfully be performed via a minimally invasive apical approach without the need for cardiopulmonary bypass. The early results in this initial series are encouraging. This initial experience suggests that the minimally invasive transapical approach is a viable alternative for patients in whom open-heart surgery is not feasible or poses unacceptable risks.

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PubMed2006

Transapical transcatheter aortic valve implantation in humans: initial clinical experience.

BACKGROUND: Aortic valve replacement with cardiopulmonary bypass is currently the treatment of choice for symptomatic aortic stenosis but carries a significant risk of morbidity and mortality, particularly in patients with comorbidities. Recently, percutaneous transfemoral aortic valve implantation has been proposed as a viable alternative in selected patients. We describe our experience with a new, minimally invasive, catheter-based approach to aortic valve implantation via left ventricular apical puncture without cardiopulmonary bypass or sternotomy. METHODS AND RESULTS: A left anterolateral intercostal incision is used to expose the left ventricular apex. Direct needle puncture of the apex allows introduction of a hemostatic sheath into the left ventricle. The valve prosthesis, constructed from a stainless steel stent with an attached trileaflet equine pericardial valve, is crimped onto a valvuloplasty balloon. The prosthetic valve and balloon catheter are passed over a wire into the left ventricle. Positioning within the aortic annulus is confirmed by fluoroscopy, aortography, and echocardiography. Rapid ventricular pacing is used to reduce cardiac output while the balloon is inflated, deploying the prosthesis within the annulus. Transapical aortic valve implantation was successfully performed in 7 patients in whom surgical risk was deemed excessive because of comorbidities. Echocardiographic median aortic valve area increased from 0.7 +/- 0.1 cm2 (interquartile range) to 1.8 +/- 0.8 cm2 (interquartile range). There were no intraprocedural deaths. At a follow up of 87 +/- 56 days, 6 of 7 patients remain alive and well. CONCLUSIONS: This initial experience suggests that transapical aortic valve implantation without cardiopulmonary bypass is feasible in selected patients with aortic stenosis.

Age Factors↗
PubMed2006

Early revascularization and long-term survival in cardiogenic shock complicating acute myocardial infarction.

CONTEXT: Cardiogenic shock remains the major cause of death for patients hospitalized with acute myocardial infarction (MI). Although survival in patients with cardiogenic shock complicating acute MI has been shown to be significantly higher at 1 year in those receiving early revascularization vs initial medical stabilization, data demonstrating long-term survival are lacking. OBJECTIVE: To determine if early revascularization affects long-term survival of patients with cardiogenic shock complicating acute MI. DESIGN, SETTING, AND PATIENTS: The Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial, an international randomized clinical trial enrolling 302 patients from April 1993 through November 1998 with acute myocardial infarction complicated by cardiogenic shock (mean [SD] age at randomization, 66 [11] years); long-term follow-up of vital status, conducted annually until 2005, ranged from 1 to 11 years (median for survivors, 6 years). MAIN OUTCOME MEASURES: All-cause mortality during long-term follow-up. RESULTS: The group difference in survival of 13 absolute percentage points at 1 year favoring those assigned to early revascularization remained stable at 3 and 6 years (13.1% and 13.2%, respectively; hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.57-0.97; log-rank P = .03). At 6 years, overall survival rates were 32.8% and 19.6% in the early revascularization and initial medical stabilization groups, respectively. Among the 143 hospital survivors, a group difference in survival also was observed (HR, 0.59; 95% CI, 0.36-0.95; P = .03). The 6-year survival rates for the hospital survivors were 62.4% vs 44.4% for the early revascularization and initial medical stabilization groups, respectively, with annualized death rates of 8.3% vs 14.3% and, for the 1-year survivors, 8.0% vs 10.7%. There was no significant interaction between any subgroup and treatment effect. CONCLUSIONS: In this randomized trial, almost two thirds of hospital survivors with cardiogenic shock who were treated with early revascularization were alive 6 years later. A strategy of early revascularization resulted in a 13.2% absolute and a 67% relative improvement in 6-year survival compared with initial medical stabilization. Early revascularization should be used for patients with acute MI complicated by cardiogenic shock due to left ventricular failure. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00000552.

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PubMed2006

Catheter thrombosis during primary percutaneous coronary intervention for acute ST elevation myocardial infarction despite subcutaneous low-molecular-weight heparin, acetylsalicylic acid, clopidogrel and abciximab pretreatment.

BACKGROUND: Subcutaneous enoxaparin is increasingly employed as the antithrombin of choice in non-ST elevation myocardial infarction and in conjunction with various fibrinolytic regimens in acute ST elevation myocardial infarction (STEMI). Few data exist describing the use of subcutaneous or intravenous enoxaparin as an anticoagulant in the highly thrombotic setting of primary percutaneous coronary intervention (PCI) for STEMI. METHODS: The Which Early ST Elevation Therapy (WEST) study compared fibrinolysis (with and without early cardiac catheterization) with primary PCI in a setting that expedited both strategies on first medical contact. Patients assigned primary PCI are administered acetylsalicylic acid 325 mg, clopidogrel 300 mg and subcutaneous enoxaparin 1 mg/kg before transport to a PCI centre. Of 36 initial patients treated with primary PCI, three patients had procedures that were complicated by extensive thrombosis within coronary catheters and on PCI equipment. RESULTS: Index cases were men aged 43 to 68 years who presented with confirmed STEMI and angiographically proven acute total or subtotal occlusion of a major epicardial coronary segment. During PCI, performed 76 min to 102 min following enoxaparin administration, a clot developed within the guide catheter or on the coronary guidewires and balloon catheter shafts, thus necessitating the replacement of all PCI equipment. In one case, there was evidence of continued intracoronary clot propagation and embolization. CONCLUSION: A single, conventional, weight-adjusted dose of subcutaneous enoxaparin before expedited primary PCI for STEMI may not provide a reliable antithrombotic effect. Supplementary intravenous enoxaparin is now strongly recommended within the WEST study, and a substudy evaluating pre- and postprocedural antifactor Xa activity has been initiated.

Abciximab↗
PubMed2006

Percutaneous aortic valve implantation retrograde from the femoral artery.

BACKGROUND: Percutaneous aortic valve implantation by an antegrade transvenous approach has been described but is problematic. Retrograde prosthetic aortic valve implantation via the femoral artery has potential advantages. Percutaneous prosthetic aortic valve implantation via the femoral arterial approach is described and the initial experience reported. METHODS AND RESULTS: The valve prosthesis is constructed from a stainless steel stent with an attached trileaflet equine pericardial valve and a fabric cuff. After routine aortic balloon valvuloplasty, a 22F or 24F sheath is advanced from the femoral artery to the aorta. A steerable, deflectable catheter facilitates manipulation of the prosthesis around the aortic arch and through the stenotic valve. Rapid ventricular pacing is used to reduce cardiac output while the delivery balloon is inflated to deploy the prosthesis within the annulus. Percutaneous aortic prosthetic valve implantation was attempted in 18 patients (aged 81+/-6 years) in whom surgical risk was deemed excessive because of comorbidities. Iliac arterial injury, seen in the first 2 patients, did not recur after improvement in screening and access site management. Implantation was successful in 14 patients. After successful implantation, the aortic valve area increased from 0.6+/-0.2 to 1.6+/-0.4 cm2. There were no intraprocedural deaths. At follow-up of 75+/-55 days, 16 patients (89%) remained alive. CONCLUSIONS: This initial experience suggests that percutaneous transarterial aortic valve implantation is feasible in selected high-risk patients with satisfactory short-term outcomes.

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PubMed2006

Percutaneous transvenous mitral annuloplasty: initial human experience with device implantation in the coronary sinus.

BACKGROUND: Mitral annuloplasty is the most common surgical procedure performed for ischemic mitral regurgitation (MR). Surgical mitral annuloplasty is limited by morbidity, mortality, and MR recurrence. We evaluated the safety and feasibility of a transvenous catheter-delivered implantable device to provide a percutaneous alternative to surgical mitral annuloplasty. METHODS AND RESULTS: Five patients with chronic ischemic MR underwent percutaneous transvenous implantation of an annuloplasty device in the coronary sinus. Implantation was successful in 4 patients. Baseline MR in the entire group was grade 3.0+/-0.7 and was reduced to grade 1.6+/-1.1 at the last postimplantation visit when the device was intact or the last postprocedural visit in the patient in whom the device was not successfully implanted. Separation of the bridge section of the device occurred in 3 of 4 implanted devices and was detected at 28 to 81 days after implantation. There were no postprocedural device-related complications. CONCLUSIONS: Percutaneous implantation of a device intended to remodel the mitral annulus is feasible. Initial experience suggests a possible favorable effect on MR. Percutaneous transvenous mitral annuloplasty warrants further evaluation as a less invasive alternative to surgical annuloplasty.

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PubMed2006

Techniques for percutaneous closure of prosthetic paravalvular leaks.

Percutaneous transcatheter closure techniques are now routinely applied in the management of atrial and ventricular septal defects, patent ductus arteriosus, and other pathological cardiac and vascular communications. Recently, these same techniques have been applied to paravalvular defects. Reports are few; success variable and techniques vary widely. We review the current considerations and techniques of percutaneous transcatheter closure of paravalvular leaks.

Bioprosthesis↗
PubMed2006

Percutaneous closure of prosthetic paravalvular leaks: case series and review.

BACKGROUND: Paravalvular leaks (PVLs) are a well-recognized complication of prosthetic valve replacement. Most are asymptomatic and benign, but some may cause symptoms due to a large regurgitant volume or hemolysis. Medical therapy is palliative, while reoperation carries significant morbidity and mortality. Percutaneous transcatheter closure techniques, now routinely applied in the management of pathological cardiac and vascular communications, may be adaptable to PVL closure, potentially offer symptomatic relief. METHODS: We reviewed our experience with attempted percutaneous closure of PVLs, using data from medical and procedural records. RESULTS: Between 2001 and 2004, 14 procedures were performed in 10 patients, all under general anesthesia, with transesophageal and radiographic guidance. Mitral (9) and aortic (1) valve replacements were involved, both mechanical and bioprosthetic. A variety of devices were used, including atrial septal occluders, patent ductus arteriosus occluders, and coils (all of label use). Six had a single procedure, which was technically successful in four: in two, the PVL could not be crossed. Four underwent a second procedure, which was technically successful in three; in one the previously deployed device was dislodged necessitating urgent, but ultimately uneventful, surgical removal and leak repair. One patient had transient severe hemolysis, which resolved after 1 week. At 1-year follow-up (9/10 pts) three had died, five had sustained symptomatic improvement while 1 patient with a residual leak still required regular blood transfusions. CONCLUSIONS: Percutaneous closure of PVLs is time-consuming but feasible in selected patients, with a reasonable degree of technical and clinical success. A second procedure may be necessary and a variety of complications can occur.

Cardiac Catheterization↗
PubMed2006

Percutaneous closure of a para-anastomotic abdominal aortic graft leak.

Para-anastomotic graft leaks are a potential complication following surgical repair of an aortic aneurysm. Reoperation may be associated with significant morbidity and mortality. We report successful percutaneous transcatheter closure of an anastomotic graft leak utilizing an occluder device.

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PubMed2006

Rapid pacing to facilitate transcatheter prosthetic heart valve implantation.

OBJECTIVES: We describe the technique of, and our experience with, rapid ventricular burst pacing to facilitate transcatheter heart valve implantation. BACKGROUND: Endovascular therapeutic procedures frequently require the precise placement of implantable devices. The precision of transcatheter device deployment may be hampered by cardiac motion or the effects of intravascular flow. Burst pacing is associated with a reduction in stroke volume, cardiac output, transvalvular flow, and cardiac motion. METHODS: Rapid pacing was used in 40 consecutive patients with severe aortic stenosis undergoing implantation of catheter-delivered prosthetic valves. Clinical, procedural, and hemodynamic records were reviewed. RESULTS: A mean of 5 +/- 2 burst pacing sequences at rates of 150-220 min(-) (1) were used during balloon valvuloplasty and valve deployment. The duration of pacing required during valve deployment was 12 +/- 3 sec. Pacing was relatively well tolerated when cautiously used with judicious recovery intervals and pressor support. Rapid pacing was associated with a rapid and effective reduction in systemic blood pressure, pulse pressure, transvalvular flow as well as cardiac and catheter motion. CONCLUSIONS: Rapid pacing is a relatively reliable technique to facilitate precise transcatheter deployment of prosthetic heart valves and other endovascular therapeutic devices.

Aged, 80 and over↗
PubMed2006

An early revascularization strategy is associated with a survival benefit for diabetic patients in cardiogenic shock after acute myocardial infarction.

BACKGROUND: The role of diabetes mellitus (DM) in cardiogenic shock (CS) complicating an acute myocardial infarction (AMI) is not well understood. Previous studies have reported an in-hospital mortality rate for patients with DM and CS of about 60%. OBJECTIVES: This study compares the 1-year mortality rates of patients with DM and those without (NDM) and evaluates early revascularization (ERV) compared with initial medical stabilization (IMS) in patients with DM and CS. METHODS: Baseline characteristics, clinical and hemodynamic measures, and management were compared for 90 patients (31%) with DM and 198 with NDM (69%) who were randomized to ERV or IMS in the SHOCK Trial. RESULTS: When compared with NDM, patients with DM were of similar age but had higher rates of prior MI (44.4 vs. 27.8%, p = 0.007) and hypertension (56.2 vs. 42.5%, p = 0.04). The DM group had a lower rate of fibrinolytic therapy (44.4 vs. 60.1%, p = 0.02). In patients randomized to ERV, patients with DM had a higher rate of coronary artery bypass grafting (CABG) (50.0 vs. 30.9%, p = 0.03) despite similar rates of triple-vessel disease. The 1-year mortality rates in both groups were equivalent (58.9%). One-year mortality was not associated with diabetes (hazard ratio [HR] 1.02, 95% CI, 0.73-1.42, p = 0.91). The benefit of an ERV strategy was similar (HR [DM] 0.62; HR [NDM] 0.75, p = 0.58). Even after adjusting for the imbalance in CABG rates, 1-year mortality was not associated with DM. CONCLUSION: Diabetes mellitus is not a predictor of 1-year mortality in CS after AMI. The benefit from an ERV strategy is similar for DM and NDM. The management strategies and influence of DM on mortality in CS deserve further evaluation.

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PubMed2006

Restrictive physiology in cardiogenic shock: observations from echocardiography.

BACKGROUND: Left ventricular diastolic abnormalities are associated with adverse outcome in myocardial infarction. Intra-aortic balloon pump (IABP) support is associated with improved diastolic filling. In the SHOCK trial and registry, average left ventricular ejection fraction (LVEF) was approximately 30%, higher than expected based on the classic paradigm. We hypothesized that restrictive physiology plays a role in cardiogenic shock (CS). METHODS: Echocardiograms obtained during the SHOCK trial within 24 hours of randomization were centrally interpreted. Patients with quantifiable mitral E-wave deceleration time were included (n = 64). The restrictive filling pattern was defined as deceleration time < 140 milliseconds. RESULTS: The restrictive pattern was seen in 60.9% of patients studied. Patients with this pattern had lower LVEF (31.1% vs 39.0%, P = .02) and higher wall motion score index (2.1 vs 1.8, P = .05). Patients with restriction were more likely to have IABP support during echocardiography (73.7% vs 43.5%, P = .03). There was no difference with and without restriction in demographic and hemodynamic variables or in mitral regurgitation degree or extent of coronary disease. The restrictive pattern had positive predictive value of 80% for pulmonary capillary wedge pressure > or = 20 mm Hg. Thirty-day survival was 53.9% with restriction versus 68.0% without restriction, P = .31. There was no difference in New York Heart Association class at 1 year between groups. CONCLUSIONS: The restrictive filling pattern is common in patients with CS, which may suggest that diastolic dysfunction contributes to CS pathogenesis. Patients with the restrictive pattern had lower LVEF despite IABP support. An association between the restrictive pattern and mortality was not demonstrated; power was limited by sample size.

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PubMed2006

Percutaneous aortic valve implantation: a case report.

The present case demonstrates the percutaneous implantation of a bioprosthetic valve in a patient with severe aortic stenosis. An 85-year-old man with significant comorbidities was determined to be at unacceptable risk with traditional surgical valve replacement. Percutaneous aortic valve implantation was performed, was successful and uncomplicated, with significant clinical and hemodynamic improvement. Currently, this procedure is an option only for symptomatic patients who are not appropriate candidates for surgical valve replacement.

Aged, 80 and over↗
PubMed2005

Comparison of percutaneous coronary intervention and coronary artery bypass grafting after acute myocardial infarction complicated by cardiogenic shock: results from the Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial.

BACKGROUND: The Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial demonstrated the survival advantage of emergency revascularization versus initial medical stabilization in patients developing cardiogenic shock after acute myocardial infarction. The relative merits of coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI) in patients with shock have not been defined. The objective of this analysis was to compare the effects of PCI and CABG on 30-day and 1-year survival in the SHOCK trial. METHODS AND RESULTS: Of the 302 trial patients, 128 with predominant left ventricular failure had emergency revascularization. The selection of revascularization procedures was individualized. Eighty-one patients (63.3%) had PCI, and 47 (36.7%) had CABG. The median time from randomization to intervention was 0.9 hours (interquartile range [IQR], 0.3 to 2.2 hours) for PCI and 2.7 hours (IQR, 1.3 to 5.5 hours) for CABG. Baseline demographics and hemodynamics were similar, except that there were more diabetics (48.9% versus 26.9%; P=0.02), 3-vessel disease (80.4% versus 60.3%; P=0.03), and left main coronary disease (41.3% versus 13.0%; P=0.001) in the CABG group. In the PCI group, 12.3% had 2-vessel and 2.5% had 3-vessel interventions. In the CABG group, 84.8% received > or =2 grafts, 52.2% received > or =3 grafts, and 87.2% were deemed completely revascularized. The survival rates were 55.6% in the PCI group compared with 57.4% in the CABG group at 30 days (P=0.86) and 51.9% compared with 46.8%, respectively, at 1 year (P=0.71). CONCLUSIONS: Among SHOCK trial patients randomized to emergency revascularization, those treated with CABG had a greater prevalence of diabetes and worse coronary disease than those treated with PCI. However, survival rates were similar. Emergency CABG is an important component of an optimal treatment strategy in patients with cardiogenic shock, and should be considered a complementary treatment option in patients with extensive coronary disease.

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PubMed2005

Proximal protection during saphenous vein graft angioplasty: the Kerberos embolic protection system.

Percutaneous intervention in the setting of aortocoronary saphenous vein graft disease is associated with a significant risk of distal embolization. Devices intended to minimize the clinical impact of embolization have primarily utilized distally placed occlusive balloons or filters. Although such systems are often effective, distal protection does have limitations. We report a novel proximal embolic protection and rinsing system intended to overcome some of these limitations.

Angioplasty, Balloon, Coronary↗
PubMed2005

Percutaneous closure of an aortic prosthetic paravalvular leak with an Amplatzer duct occluder.

Following aortic valve replacement, up to 5% of patients may develop clinically significant paravalvular leaks. Reoperation is associated with higher mortality and an excess risk of recurrent paravalvular insufficiency. No specifically designed transcatheter device is available for paravalvular leak repair. We describe in a patient with severe aortic prosthetic paravalvular leak the use of an Amplatzer duct occluder device resulting in effective closure and symptomatic improvement.

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PubMed2005

Venture wire control catheter.

We wished to test the safety and efficacy of a novel wire control catheter for use during percutaneous coronary intervention. The ability to vary the angulation of the tip of an intravascular guidewire would often be desirable. Previous attempts to produce deflectable-tip guidewire systems have met with limited success. The Venture wire control catheter (Velocimed, Minneapolis, MN) was used to facilitate percutaneous coronary intervention in 20 patients. There were no device-related complications. Percutaneous coronary intervention was successful in all patients. Our initial experience with the Venture wire control catheter has been favorable.

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