Biomedical subjects

Patrick M McCarthy

Publications and source records attributed to Patrick M McCarthy.

115 records · Page 7Linked to original sources

PubMed2002

Left ventricular splints and wraps for end-stage heart failure: a new approach in the new millennium.

The epidemic of heart failure and its subsequent effect on public health policy is escalating. Cardiac transplantation continues to be limited by the shortage of donor organs, and the current generation of mechanical circulatory support devices has not yet approached the goal of destination therapy. A better understanding of the role of left ventricular remodeling in the development of heart failure has resulted in novel surgical therapies and devices that may reverse or retard the remodeling process.

Cardiac Surgical Procedures↗

PubMedDate not supplied

Device-based left ventricular geometry change for heart failure treatment: developmental work and current status.

BACKGROUND: Device-based left ventricular (LV) geometry change is a new concept in the treatment of heart failure that reduces LV wall stress and improves cardiac function by reducing effective LV radius. Ventricular geometry change is achieved by placement of three Myosplint devices to bisect the LV and to create two smaller LV chambers. METHODS AND RESULTS: Since the first animal experiment in June 1997, the Myosplint has been tested extensively in a series of animal studies using a pacing-induced, canine dilated cardiomyopathy model. Device-based LV geometry change decreased LV wall stress, improved systolic function, and maintained diastolic function, resulting in an improvement in myocardial energetics. An acute human feasibility study during heart transplant surgery was started in July 1999. While awaiting the arrival of the donor heart, the Myosplint was implanted in the recipient LV in 5 patients. The device was easily applied on a beating heart without complications related to the device or the procedure in any of the patients. LV wall stress was significantly decreased after tightening of the device. Clinical safety studies with chronic Myosplint implantation were begun in Germany in June 2000 and in the United States in February 2001. There have been a total of 21 patients receiving the implant without evidence of bleeding, muscle tearing, severe arrhythmia, or thrombus formation associated with the implant. CONCLUSIONS: Device-based geometry change has been demonstrated to be practical, effective, and safe.

Animals↗

PubMedDate not supplied

Autologous cell transplantation for the treatment of damaged myocardium.

Autologous cell transplantation for the treatment of damaged myocardium after myocardial infarction is becoming an increasingly promising strategy. This form of treatment can be divided into 2 treatment strategies: The first uses differentiated cell types to replace the scarred tissue with living cells, while the second strategy uses stem cells in an attempt to regenerate myocardium. Over the past decade, multiple cell types have been used in animal studies, and clinical trials to determine the safety of injecting and engrafting skeletal myoblasts into damaged myocardium are presently being conducted. Animals studies focused on using stem cells to regenerate damaged myocardium have shown a naturally occurring reparative process that consists of up-regulation of progenitor cell release from the bone marrow after myocardial infarction, homing of these cells to the injured tissue, and differentiation of these progenitor cells into vascular cells and cardiac myocytes within the infarcted tissue. Unfortunately, this process occurs with great infrequency. Strategies to regenerate myocardium with stem cells either extract stem cells from the bone marrow and inject these cells into the damaged area or they attempt to increase the efficiency of the natural reparative process by increasing the mobilization of bone marrow-derived stem cells after myocardial infarction. This review summarizes the field of cell transplantation over the past decade, discusses areas of controversy, and proposes an outline of advancements that need to be made in both the clinical and scientific arenas for autologous cell transplantation to fully reach its clinical potential.

Animals↗

PubMedDate not supplied

Device based left ventricular shape change: validation of conductance technology in shape changed hearts.

We have reported that device based left ventricular (LV) shape change, accomplished by Myosplint, improved LV systolic function by three-dimensional echocardiography (3-D echo). However, evaluation of this device using the pressure-volume relationship is still important. This study was conducted to validate the use of conductance technology for this evaluation in shape-changed hearts. An ex vivo study using excised ovine hearts (n = 11) and an in vivo study using a canine pacing-induced heart failure model (n = 11) were performed. Three Myosplints were implanted. Before and after the shape changes, volumes measured by a conductance catheter were compared with volumes measured by the amount of saline in the ex vivo study or by 3-D echo in the in vivo study. The conductance volumes were linearly correlated with the saline volumes (r2 = 0.961+/-0.046; p < 0.0001) in the ex vivo study and with 3-D echo volumes (r2 = 0.757+/-0.220; p < 0.0001) in the in vivo study. The conductance volumes were linearly correlated with LV volumes even in the shape-changed hearts. This technology can be used to evaluate pressure-volume loops in the shape-changed hearts as long as the conductance volume is calibrated by a reliable method.

Animals↗

PubMedDate not supplied

Optimal mitral annular and subvalvular shape change created by the Coapsys device to treat functional mitral regurgitation.

We have reported that the Myocor Coapsys (Myocor, Inc, Maple Grove, MN) device treated functional mitral regurgitation (MR) by reducing mitral annular dimension and repositioning papillary muscles. This study was conducted to evaluate the optimal Coapsys device sizing level. The Coapsys device was implanted in seven dogs after induction of MR by rapid ventricular pacing. The device consists of anterior and posterior pads connected by a subvalvular cord. The device was tightened in 5% increments of the left ventricular epicardial to epicardial dimension up to 40%. Hemodynamic and echocardiographic measurements were repeated at each tightening level. The Coapsys significantly reduced or eliminated functional MR, and the reduction was maximized at the 30% tightening level or lower in all cases. Although the left ventricular end diastolic volume decreased significantly, forward stroke volume was maintained until the 35% tightening level. The forward ejection fraction significantly increased from 33 +/- 24% at baseline to 62 +/- 42% at 40% tightening level. Mean aortic pressure decreased slightly but significantly. The Coapsys device can be applied over a broad range of tightening levels with significant reduction in MR without negative physiologic impact. This feature makes the device usable [corrected] in a variety of clinical settings.

Animals↗

PubMedDate not supplied

Reduction of mitral regurgitation using the Coapsys device: a novel ex vivo method using excised recipients' hearts.

The purpose of this study was to evaluate the ex vivo effects of the Coapsys device upon functional mitral regurgitation (MR) in human hearts. We used seven excised hearts from patients who underwent cardiac transplantation. All patients had functional MR of grade 2 or greater associated with dilated (n = 3) or ischemic (n = 4) cardiomyopathy. After the aortic valve was removed, the left ventricle was pressurized from the aorta with saline at a constant pressure. The degree of MR was then subjectively graded from the opened left atrium (from 0 to 4). The last three studies included volumetric measurements of MR. By tightening the device, the mean MR grade was reduced from 3.3 +/- 0.8 to 1.1 +/- 0.4 (p = 0.0002). In the quantitative analysis, mean regurgitation volume was reduced from 1,108 +/- 1,134 ml/min to 236 +/- 89 ml/min (p = not significant). The mitral annular septal-lateral dimension decreased from 2.0 +/- 0.3 cm to 1.6 +/- 0.5 (p = 0.043). The Coapsys device reduced functional MR in the ex vivo study using excised dilated hearts.

Cardiomyopathy, Dilated↗

PubMedDate not supplied

Initial safety and feasibility clinical trial of the myosplint device.

BACKGROUND: The Myocor Myosplint device is a passive implantable device for the treatment of heart failure by changing the geometry of the left ventricle (LV). AIM: The purpose of this evaluation was to describe the first human experience with the Myosplint device to demonstrate safety and feasibility. METHODS: Of the first consecutive 21 patients, 9 patients received a Myosplint device alone while 12 patients underwent a mitral valve repair as well. Safety and efficacy data were gathered at enrollment and during follow-up. RESULTS: No serious device-related adverse events or device failures were observed. Three patients died during the follow-up period, and 2 patients underwent heart transplantation. There was a significant improvement in the New York Heart Association (NYHA) functional class from 3.0 +/- 0.3 at baseline to 2.1 +/- 0.7 at 6 months (p = 0.001). Both LV end-diastolic and end-systolic volumes had decreased at follow-up. The LV ejection fraction significantly increased in the Myosplint alone group (from 17.1 +/- 4.0% at baseline to 21.8 +/- 4.1% at 3 months and 23.1 +/- 7.2% at 6 months) but not in the Myosplint and mitral valve repair group. The mitral regurgitation (MR) grade had a significant (p = 0.002) linear relationship with the NYHA functional class. CONCLUSIONS: The initial clinical experience of the Myosplint device demonstrated both safety and feasibility, validating the LV shape change concept in humans. A remodeling solution must, however, include MR resolution, to illustrate the need for a device that can simultaneously reduce or eliminate functional MR off-pump.

Adult↗