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Biomedical subjects

Peter C Block

Publications and source records attributed to Peter C Block.

36 records · Page 2Linked to original sources
PubMed2004

Beating heart catheter-based edge-to-edge mitral valve procedure in a porcine model: efficacy and healing response.

BACKGROUND: Surgical edge-to-edge repair has been used in the treatment of mitral regurgitation. We evaluated the ability of a catheter-delivered clip (Evalve, Inc) to achieve edge-to-edge mitral valve approximation without cardiopulmonary bypass and the healing response of this technique. METHODS AND RESULTS: Twenty-one pigs underwent general anesthesia and left thoracotomy. A 10F flexible delivery catheter with a clip was placed into the left atrium. With echocardiographic and fluoroscopic guidance, the clip grasped and approximated the mid portion of the anterior and posterior leaflets. After a double orifice had been confirmed, the clip was detached and the catheter withdrawn. All animals survived and had successful clip placement. Three animals were euthanized at 4 weeks, 9 at 12 weeks, 1 at 17 weeks, 7 at 24 weeks, and 1 at 52 weeks. The clip was well positioned, with leaflet approximation in all animals except 1, in which the clip separated from the posterior leaflet at 4 weeks without affecting valve function. The clip was modified and implanted in 4 pigs; all were intact at 12 to 24 weeks. Scanning electron microscopy showed clip encapsulation with complete endothelialization. Mitral stenosis and thromboembolism did not develop. Two animals developed endocarditis (1 at 12 weeks and 1 at 17 weeks). Progressive healing occurred in all other animals. CONCLUSIONS: Edge-to-edge mitral valve approximation can be successfully and reliably achieved with a catheter-delivered clip without cardiopulmonary bypass, resulting in durable healing. The success of this device supports the development of a percutaneous catheter-based system for mitral valve repair.

Animals↗
PubMed2004

Left atrial structure and function after percutaneous left atrial appendage transcatheter occlusion (PLAATO): six-month echocardiographic follow-up.

OBJECTIVES: This study was designed to evaluate the effects of percutaneous left atrial appendage transcatheter occlusion (PLAATO) on the anatomic and hemodynamic properties of the mitral valve (MV) and left upper pulmonary vein (LUPV). BACKGROUND: PLAATO is a device designed to seal the neck of the left atrial (LA) appendage and reduce embolization in patients with atrial fibrillation intolerant of warfarin. The impact of deployment of this device on adjacent structures has not been reported. METHODS: Patients with atrial fibrillation participating in the ongoing study for evaluation of PLAATO were enrolled. Transesophageal echocardiographies at baseline, one, and six months were reviewed to measure LA and LUPV dimensions, degree of mitral regurgitation, stability of the device, peak MV E-wave velocity, and peak systolic and diastolic flow velocities in the LUPV. Data were analyzed by a linear mixed model for repeated measures. RESULTS: Eleven patients (mean age of 72 +/- 7 years) completed six months of follow-up. Left upper pulmonary vein diameter (mean: 1.55, 1.61, 1.54 cm, p = 0.13) and peak systolic (mean: 0.38, 0.34, 0.31 m/s, p = 0.72) and diastolic flow velocities (mean: 0.39, 0.40, 0.42 m/s, p = 0.46) did not differ over the follow-up period. Left atrial size, mitral regurgitation severity, and MV peak E-wave velocities (mean: 0.94, 0.94, 0.82 m/s, p = 0.58) showed no significant change from baseline. The devices remained stable at their sites of deployment with minimal residual flow around them. CONCLUSIONS: PLAATO achieved an adequate seal of the neck of the left atrial appendage without significant effect on the structure or function of the LA and LUPV.

Aged↗
PubMed2004

Off-pump vs conventional coronary artery bypass grafting: early and 1-year graft patency, cost, and quality-of-life outcomes: a randomized trial.

CONTEXT: Previous trials of off-pump coronary artery bypass (OPCAB) have enrolled selected patients and have not rigorously evaluated long-term graft patency. A preliminary report showed OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with conventional coronary artery bypass grafting (CABG). OBJECTIVE: To assess graft patency, clinical and quality-of-life outcomes, and cost among patients while in the hospital and at 1-year follow-up. DESIGN, SETTING, AND PATIENTS: Randomized controlled trial of patients unselected for coronary anatomy, ventricular function, or comorbidities between March 10, 2000, and August 20, 2001, at a US academic center. A total of 200 patients were enrolled; 3 patients were withdrawn after randomization for mitral valve repair or replacement. Follow-up was complete for 197 patients at 30 days; 185 at 1 year. INTERVENTIONS: One surgical session consisting of elective OPCAB or CABG with cardiopulmonary bypass. The surgeon had extensive experience performing off-pump surgery; patients were subsequently managed by blinded protocols. MAIN OUTCOME MEASURES: Coronary angiography documented graft patency prior to hospital discharge and at 1 year; health-related quality of life; and cost of the index and subsequent hospitalization(s). RESULTS: Graft patency was similar for OPCAB and conventional CABG with cardiopulmonary bypass at 30 days (absolute difference, 1.3%; 95% confidence interval [CI], -0.66% to 3.31%; P =.19) and at 1 year (absolute difference, -2.2%; 95% CI, -6.1% to 1.7%; P =.27). Rates of death, stroke, myocardial infarction, angina, and reintervention were similar at 30 days and 1 year. There were no significant differences in health-related quality of life. Mean total hospitalization cost per patient at hospital discharge was 2272 dollars (95% CI, 755 dollars-3732 dollars) less for OPCAB (P =.002) and 1955 dollars (95% CI, -766 dollars to 4727 dollars) less at 1 year (P =.08). CONCLUSIONS: In this randomized single-surgeon trial among unselected patients with angiographic follow-up, OPCAB achieved similar graft patency in the hospital and at 1 year. Cardiac outcomes and health-related quality of life at 30 days and 1 year were similar and patients incurred a lower cost. OPCAB may provide complete revascularization that is durable and cost-effective.

Aged↗
PubMed2004

Transcatheter patent foramen ovale closure for secondary prevention of paradoxical embolic events: acute results from the FORECAST registry.

Patients with patent foramen ovale (PFO) and paradoxical embolism are at increased risk for recurrent events. Percutaneous PFO closure is a new treatment modality aimed at secondary prevention. We report the multicenter experience of interventional closure of PFO using two different devices in 272 patients. The mean age was 51 +/- 14.2 years and 52.9% were males. The implantation procedure resulted in an initial complete shunt closure rate of 74.3% with a periprocedural complication rate of 6.6%. There were no deaths or pericardial tamponade. The mean procedure time was less than 44 min under either conscious sedation, local or general anesthesia. This is the largest report to date demonstrating the procedural safety, reliability, and feasibility of the transcatheter PFO closure technique with the STARFlex and CardioSEAL septal implants. Randomized clinical trials are currently in progress to identify patients most likely to benefit from this intervention.

Adult↗
PubMed2004

Percutaneous left atrial appendage transcatheter occlusion for patients with atrial fibrillation unable to take warfarin.

Anticoagulation with warfarin for atrial fibrillation is frequently difficult. A transcatheter method to exclude the left atrial appendage from the circulation could be an advantage for selected patients. Percutaneous left atrial appendage transcatheter occlusion is a catheter-based delivery of an occlusive nitinol cage to the neck of the left atrial appendage. The device obliterates the left atrial appendage, eliminating a major source of thromboembolism. Animal studies have confirmed device coverage with an endocardial layer within 6 months and distal atrial appendage fibrosis. A standard transseptal approach from the right femoral vein is used. Patients leave the hospital within 1 day. Six-month follow-up of European and US safety and efficacy trials has shown favorable outcomes in minimizing thromboembolic events and few complications related to placement or healing of the device. Further clinical studies will be needed to establish which patients will be best treated with this device.

Age Factors↗
PubMed2003

Incidence of aspirin nonresponsiveness using the Ultegra Rapid Platelet Function Assay-ASA.

We report the incidence of aspirin nonresponsiveness in a prospective, multicenter registry (n=422 patients) to be 23% using the Ultegra Rapid Platelet Function Assay-ASA, and determined a history of coronary artery disease to be associated with twice the odds of being an aspirin nonresponder (odds ratio 2.01, 95% confidence interval 1.189 to 3.411, p=0.009). Further prospective studies are needed to correlate aspirin nonresponsiveness to adverse clinical events.

Aspirin↗
PubMed2003

Endovascular edge-to-edge mitral valve repair: short-term results in a porcine model.

BACKGROUND: The edge-to-edge technique is an accepted method for the surgical repair of a regurgitant mitral valve. This study reports the initial use of an endovascular technology that enables a double-orifice edge-to-edge mitral valve repair without cardiopulmonary bypass in an animal model. METHODS AND RESULTS: Adult pigs (n=14) were anesthetized, and left thoracotomy was performed for epicardial echo imaging. Using femoral vein access, a steerable guide catheter was placed transseptally into the left atrium. An implantable clip designed to grasp and approximate the middle scallops of the anterior and posterior mitral leaflets was introduced through the guide catheter. The clip was opened in the left atrium, advanced through the mitral orifice, and retracted to grasp the leaflet edges. When a functional double-orifice valve was confirmed by echo, the clip was closed to coapt the leaflets and detached from the delivery catheter. Before final clip detachment, echo demonstrated a double orifice in all 14 animals. In 2 studies, the clip released from the anterior mitral leaflet. Retrospective analysis of echo images indicated an incomplete grasp of the anterior leaflet. Immediate postmortem examination revealed that the clip successfully approximated the middle scallops of the anterior and posterior leaflets in all 12 double-orifice studies. CONCLUSIONS: This study demonstrates for the first time that an endovascular system can be successfully used to perform the edge-to-edge repair technique in a nondiseased porcine model. This technique is potentially applicable as a percutaneous catheterization laboratory procedure for the treatment of mitral regurgitation in humans.

Animals↗
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

Comparison of in-hospital and one-year outcomes in patients with left ventricular ejection fractions or=50% having percutaneous coronary revascularization.

Outcome studies of percutaneous coronary intervention (PCI) with conventional balloon angioplasty have established increased in-hospital and 1-year mortality in patients with left ventricular (LV) dysfunction compared with others. It is unclear whether recent PCI practice innovations, including stents and adjunctive pharmacotherapy, have made PCI safer and more effective in patients with LV dysfunction. We evaluated the influence of LV ejection fraction (EF) indexes on in-hospital and 1-year outcomes in 1,458 patients within the National Heart, Lung, and Blood Institute-sponsored Dynamic Registry. Patients (n = 300) with acute myocardial infarction were excluded. The remaining 1,158 patients were subdivided into 3 categories: group 1, EF or=50% (n = 866). We determined the frequency of individual and composite adverse events (death/myocardial infarction [MI]/coronary artery bypass grafting) at discharge and 1 year. In the Dynamic Registry patients, mean EF in the 3 groups was 32%, 45%, and 62% and in-hospital mortality was 3.0%, 1.6%, and 0.1%, respectively (p <0.001). The composite end point of death/MI was also significant, but other in-hospital adverse events did not differ between groups. The respective mortality rates were 11.0%, 4.5%, and 1.9% (p <0.001) after 1 year. The composite end points of death/MI and death/MI/coronary artery bypass grafting also occurred more frequently in group 1 patients. Thus, significant LV dysfunction was still associated with increased in-hospital and 1-year mortality in patients having contemporary PCI.

Aged↗
PubMed2003

Percutaneous mitral valve repair for mitral regurgitation.

Mitral regurgitation (MR) associated with, ischemic, and degenerative (prolapse) disease, contributes to left ventricular (LV) dysfunction due to remodeling, and LV dilation, resulting in worsening of MR. Mitral valve (MV) surgical repair has provided improvement in survival, LV function and symptoms, especially when performed early. Surgical repair is complex, due to diverse etiologies and has significant complications. The Society for Thoracic Surgery database shows that operative mortality for a 1st repair is 2% and for re-do repair is 4 times that. Cardiopulmonary bypass and cardiac arrest are required. The attendant morbidity prolongs hospitalization and recovery. Alfieri simplified mitral repair using an edge-to-edge technique which subsequently has been shown to be effective for multiple etiologies of MR. The MV leaflers are typically brought together by a central suture producing a double orifice MV without stenosis. Umana reported that MR decreased from grade 3.6 +/- 0.5 to 0.8 +/- 0.4 (P < 0.0001) and LV ejection fraction increased from 33 +/- 13% to 45 +/- 11% (P = 0.0156). In 121 patients, Maisano reported freedom from re-operation of 95 +/- 4.8% with up to 6 year follow-up. Oz developed a MV "grasper" that is directly placed via a left ventriculotomy and coapts both leaflets which are then fastened by a graduated spiral screw. An in-vitro model using explanted human valves showed significant reduction in MR and in canine studies, animals followed by serial echo had persistent MV coaptation. At 12 weeks the device was endothelialized. These promising results have paved the way for a percutaneous or minimally invasive-off pump mitral repair. Evalve has developed catheter-based technology, which, by apposing the edges of a regurgitant MV, results in edge-to-edge repair. Release of the device is done after echo and fluoroscopic evaluation under normal loading conditions. If the desired effect is not produced the device can be repositioned or retrieved. Animal studies show excellent healing, with incorporation of the device into the leaflets at 6-10 weeks with persistent coaptation. Another percutaneous approach has been to utilize the proximity of the coronary sinus (CS) to the mitral annulus (MA). Placement of a self-compressing device in the CS along the region of the posterior MA has, in canine models, reduced MR and addresses the issues of MA dilation and its contribution to MR. Ongoing studies are underway for both techniques.

Angioplasty, Balloon, Coronary↗
PubMed2003

Debulking for in-stent restenosis in the brachytherapy era: does it still have a role?

Despite the advent of intracoronary brachytherapy, treatment of in-stent restenosis, particularly diffuse in-stent restenosis, remains problematic. Adjunctive debulking prior to brachytherapy may improve long-term outcomes. We review the literature and report our results of a series of patients treated with excimer laser coronary atherectomy along with balloon angioplasty and brachytherapy for in-stent restenosis. We conclude that adjunctive debulking may improve the long-term clinical outcomes of patients with diffuse in-stent restenosis treated with angioplasty and intracoronary radiation. A randomized controlled trial is warranted.

Angioplasty, Balloon, Coronary↗
PubMed2003

Updated risk adjustment mortality model using the complete 1.1 dataset from the American College of Cardiology National Cardiovascular Data Registry (ACC-NCDR).

OBJECTIVES: To revise and update a risk adjustment model for in-hospital mortality following percutaneous coronary intervention (PCI) procedures using all data from the 1.1 version of the American College of Cardiology National Cardiovascular Data Registry (ACC-NCR). BACKGROUND: A model based on data received at the ACC-NCDR from 1998-2000 was previously reported. The revision of this mortality model reflects all of the data submitted using 1.1 data specifications and collected through the second quarter of 2001. The model was applied to selected high-risk subgroups from a sample of data collected during the year 2001 from version 2.0 of the NCDR. METHODS: Data on 173,743 PCI procedures collected at the ACC-NCDR between January 1, 1998 and March 31, 2001 were analyzed. A mortality model was generated as well as separate models for presentation with and without acute myocardial infarction within 24 hours. The model was used to generate predicted mortalities that were compared to observed mortalities in more current high-risk patient subgroups in the NCDR. RESULTS: The same factors that were previously found to be associated with increased risk of PCI mortality were re-verified in the current analysis. Inclusion of the complete 1.1 dataset produced some changes in the regression weights and the constant value. Excellent discrimination was achieved in the revised model (C-Index = 0.89). The model was applied to high-risk patient groups from data collected on 76,249 during the calendar year 2001 using the 2.0 NCDR data elements and definitions. These analyses showed a high level of agreement between observed mortality of each subgroup and the predicted mortality rates generated from the revised 1.1 PCI mortality model. CONCLUSIONS: Risk adjustment models for in-hospital mortality following PCI for all patients and for those with and without recent MI were regenerated using all data collected from the 1.1 data specifications of the ACC-NCDR and validated on high-risk groups from data collected during 2001 under data version 2.0 of the NCDR. These models reflect the most up-to-date analysis of mortality prediction from this large, multi-center national database.

Aged↗
PubMed2002

Development of a risk adjustment mortality model using the American College of Cardiology-National Cardiovascular Data Registry (ACC-NCDR) experience: 1998-2000.

OBJECTIVES: We sought to develop and evaluate a risk adjustment model for in-hospital mortality following percutaneous coronary intervention (PCI) procedures using data from a large, multi-center registry. BACKGROUND: The 1998-2000 American College of Cardiology-National Cardiovascular Data Registry (ACC-NCDR) dataset was used to overcome limitations of prior risk-adjustment analyses. METHODS: Data on 100,253 PCI procedures collected at the ACC-NCDR between January 1, 1998, and September 30, 2000, were analyzed. A training set/test set approach was used. Separate models were developed for presentation with and without acute myocardial infarction (MI) within 24 h. RESULTS: Factors associated with increased risk of PCI mortality (with odds ratios in parentheses) included cardiogenic shock (8.49), increasing age (2.61 to 11.25), salvage (13.38) urgent (1.78) or emergent PCI (5.75), pre-procedure intra-aortic balloon pump insertion (1.68), decreasing left ventricular ejection fraction (0.87 to 3.93), presentation with acute MI (1.31), diabetes (1.41), renal failure (3.04), chronic lung disease (1.33); treatment approaches including thrombolytic therapy (1.39) and non-stent devices (1.64); and lesion characteristics including left main (2.04), proximal left anterior descending disease (1.97) and Society for Cardiac Angiography and Interventions lesion classification (1.64 to 2.11). Overall, excellent discrimination was achieved (C-index = 0.89) and application of the model to high-risk patient groups demonstrated C-indexes exceeding 0.80. Patient factors were more predictive in the MI model, while lesion and procedural factors were more predictive in the analysis of non-MI patients. CONCLUSIONS: A risk adjustment model for in-hospital mortality after PCI was successfully developed using a contemporary multi-center registry. This model is an important tool for valid comparison of in-hospital mortality after PCI.

Aged↗
PubMed2002

A contemporary overview of percutaneous coronary interventions. The American College of Cardiology-National Cardiovascular Data Registry (ACC-NCDR).

The American College of Cardiology (ACC) established the National Cardiovascular Data Registry (ACC-NCDR) to provide a uniform and comprehensive database for analysis of cardiovascular procedures across the country. The initial focus has been the high-volume, high-profile procedures of diagnostic cardiac catheterization and percutaneous coronary intervention (PCI). Several large-scale multicenter efforts have evaluated diagnostic catheterization and PCI, but these have been limited by lack of standard definitions and relatively nonuniform data collection and reporting methods. Both clinical and procedural data, and adverse events occurring up to hospital discharge, were collected and reported according to uniform guidelines using a standard set of 143 data elements. Datasets were transmitted quarterly to a central facility for quality-control screening, storage and analysis. This report is based on PCI data collected from January 1, 1998, through September 30, 2000.A total of 139 hospitals submitted data on 146,907 PCI procedures. Of these, 32% (46,615 procedures) were excluded because data did not pass quality-control screening. The remaining 100,292 procedures (68%) were included in the analysis set. Average age was 64 +/- 12 years; 34% were women, 26% had diabetes mellitus, 29% had histories of prior myocardial infarction (MI), 32% had prior PCI and 19% had prior coronary bypass surgery. In 10% the indication for PCI was acute MI < or =6 h from onset, while in 52% it was class II to IV or unstable angina. Only 5% of procedures did not have a class I indication by ACC criteria, but this varied by hospital from a low of 0 to a high of 38%. A coronary stent was placed in 77% of procedures, but this varied by hospital from a low of 0 to a high of 97%. The frequencies of in-hospital Q-wave MI, coronary artery bypass graft surgery and death were 0.4%, 1.9% and 1.4%, respectively. Mortality varied by hospital from a low of 0 to a high of 4.2%. This report presents the first data collected and analyzed by the ACC-NCDR. It portrays a contemporary overview of coronary interventional practices and outcomes, using uniform data collection and reporting standards. These data reconfirm overall acceptable results that are consistent with other reported data, but also confirm large variations between individual institutions.

Angioplasty, Balloon, Coronary↗
PubMed2002

Which patients benefit from percutaneous mitral balloon valvuloplasty? Prevalvuloplasty and postvalvuloplasty variables that predict long-term outcome.

BACKGROUND: Percutaneous mitral balloon valvuloplasty (PMV) results in good immediate results, particularly in patients with echocardiographic scores (Echo-Sc) < or =8. However, which variables relate to long-term outcome is unclear. METHODS AND RESULTS: We report the immediate and long-term clinical follow-up (mean, 4.2+/-3.7 years; range, 0.5 to 15) of 879 patients who underwent 939 PMV procedures. Patients were divided into 2 groups, Echo-Sc < or =8 (n=601) and Echo-Sc >8 (n=278). PMV resulted in an increase in mitral valve area from 1.0+/-0.3 to 2.0+/-0.6 cm2 in patients with Echo-Sc < or =8 and from 0.8+/-0.3 to 1.6+/-0.6 cm2 in patients with Echo-Sc >8 (P<0.0001). Although adverse events (death, mitral valve surgery, and redo PMV) were low within the first 5 years of follow-up, a progressive number of events occurred beyond this period. Nevertheless, survival (82% versus 57%) and event-free survival (38% versus 22%) at 12-year follow-up was greater in patients with Echo-Sc < or =8 (P<0.0001). Cox regression analysis identified post-PMV mitral regurgitation > or =3+, Echo-Sc >8, age, prior surgical commissurotomy, NYHA functional class IV, pre-PMV mitral regurgitation > or =2+, and higher post-PMV pulmonary artery pressure as independent predictors of combined events at long-term follow-up. CONCLUSIONS: The immediate and long-term outcome of patients undergoing PMV is multifactorial. The use of the Echo-Sc in conjunction with other clinical and morphological predictors of PMV outcome allows identification of patients who will obtain the best outcome from PMV.

Catheterization↗