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Elyse Foster

Publications and source records attributed to Elyse Foster.

12 recordsLinked to original sources
PubMed2003

New technique for measurement of left ventricular pressure in conscious mice.

Concern about the effects of anesthesia on physiological measurements led us to develop methodology to assess left ventricular (LV) pressure in conscious mice. Polyethylene-50 tubing filled with heparinized saline was implanted in the LV cavity through its apex via an abdominal approach and exteriorized to the back of the animal. This surgery was done under anesthesia with either an intraperitoneal injection of ketamine (80 mg/kg) and xylazine (5 mg/kg) (K+X) in 11 mice or isoflurane (ISF; 1.5 vol%) by inhalation in 14 mice. Postoperatively, mice were trained daily to lie quietly head first in a plastic cone. LV pressure, the first derivative of LV pressure (dP/dt), and heart rate (HR) in the conscious state were compared between the two groups at 3 days and 1 wk after recovery from surgery using a 1.4-Fr Millar catheter inserted into the LV through the tubing, with the mice lying quietly in the plastic cone. Acutely during anesthesia, K+X decreased HR (from 698 to 298 beats/min), LV systolic pressure (from 107 to 65 mmHg), and maximal dP/dt (dP/dt(max)) (from 15,724 to 4,445 mmHg/s), all P < 0.01. Similar but less marked negative chronotropic and inotropic effects were seen with ISF. HR and dP/dt(max) were decreased significantly in K+X mice 3 days after surgery compared with those anesthetized with ISF (655 vs. 711 beats/min, P < 0.05; 14,448 vs. 18,048 mmHg/s, P < 0.001) but increased to the same level as in ISF mice 1 wk after surgery. In ISF mice, recovery of function occurred rapidly and there were no differences in LV variables between 3 days and 1 wk. LV pressure and dP/dt can be measured in conscious mice with a micromanometer catheter inserted through tubing implanted permanently in the LV apex. Anesthesia with either K+X or, to a lesser extent, ISF, depressed LV function acutely. This depression of function persisted for 3 days after surgery with K+X (but not ISF) and did not recover completely until 1 wk postanesthesia.

Adrenergic alpha-Agonists↗
PubMed2003

Cardiac resynchronization therapy for the treatment of heart failure in patients with intraventricular conduction delay and malignant ventricular tachyarrhythmias.

OBJECTIVES: This study was conducted to assess the safety and effectiveness of cardiac resynchronization therapy (CRT) when combined with an implantable cardioverter defibrillator (ICD). BACKGROUND: Long-term outcome of CRT was measured in patients with symptomatic heart failure (HF), intraventricular conduction delay, and malignant ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) requiring therapy from an ICD. METHODS: Patients (n = 490) were implanted with a device capable of providing both CRT and ICD therapy and randomized to CRT (n = 245) or control (no CRT, n = 245) for up to six months. The primary end point was progression of HF, defined as all-cause mortality, hospitalization for HF, and VT/VF requiring device intervention. Secondary end points included peak oxygen consumption (VO(2)), 6-min walk (6 MW), New York Heart Association (NYHA) class, quality of life (QOL), and echocardiographic analysis. RESULTS: A 15% reduction in HF progression was observed, but this was statistically insignificant (p = 0.35). The CRT, however, significantly improved peak VO(2) (0.8 ml/kg/min vs. 0.0 ml/kg/min, p = 0.030) and 6 MW (35 m vs. 15 m, p = 0.043). Changes in NYHA class (p = 0.10) and QOL (p = 0.40) were not statistically significant. The CRT demonstrated significant reductions in ventricular dimensions (left ventricular internal diameter in diastole = -3.4 mm vs. -0.3 mm, p < 0.001 and left ventricular internal diameter in systole = -4.0 mm vs. -0.7 mm, p < 0.001) and improvement in left ventricular ejection fraction (5.1% vs. 2.8%, p = 0.020). A subgroup of patients with advanced HF (NYHA class III/IV) consistently demonstrated improvement across all functional status end points. CONCLUSIONS: The CRT improved functional status in patients indicated for an ICD who also have symptomatic HF and intraventricular conduction delay.

Aged↗
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

Isolated bundle branch block and left ventricular dysfunction.

BACKGROUND: Population studies have identified the presence of bundle branch block (BBB) as a risk factor for increased mortality in patients with known cardiac disease. It is unknown how chronic ventricular dyssynchrony resulting solely from conduction delay affects ventricular function. METHODS AND RESULTS: Subjects were retrospectively identified from the University of California, San Francisco, electrocardiogram database with QRS prolongation. Subjects who had no evidence of heart disease and had baseline and serial studies evaluating ongoing risk of coronary artery disease status and left ventricular function were followed over time. Documentation of a minimum of 2 serial evaluations of cardiac status were present in a total of 51/176 (20%) subjects with isolated BBB who constitute the study population. After a mean follow-up of 52 +/- 45 months-adjusting for differences due to age, sex, the presence of hypertension, hyperlipidemia, and diabetes mellitus-left ventricular ejection fraction diminished by -7.3 +/- 12% per year in the isolated left BBB cohort versus -1.9 +/- 4% in isolated right BBB cohort and -1.1 +/- 3% reduction in the isolated nonspecific intraventricular conduction delay cohort (P =.019). CONCLUSIONS: Left bundle branch block itself may be a cause of ventricular dysfunction.

Aged↗
PubMed2003

The alpha(1A/C)- and alpha(1B)-adrenergic receptors are required for physiological cardiac hypertrophy in the double-knockout mouse.

Catecholamines and alpha(1)-adrenergic receptors (alpha(1)-ARs) cause cardiac hypertrophy in cultured myocytes and transgenic mice, but heart size is normal in single KOs of the main alpha(1)-AR subtypes, alpha(1A/C) and alpha(1B). Here we tested whether alpha(1)-ARs are required for developmental cardiac hypertrophy by generating alpha(1A/C) and alpha(1B) double KO (ABKO) mice, which had no cardiac alpha(1)-AR binding. In male ABKO mice, heart growth after weaning was 40% less than in WT, and the smaller heart was due to smaller myocytes. Body and other organ weights were unchanged, indicating a specific effect on the heart. Blood pressure in ABKO mice was the same as in WT, showing that the smaller heart was not due to decreased load. Contractile function was normal by echocardiography in awake mice, but the smaller heart and a slower heart rate reduced cardiac output. alpha(1)-AR stimulation did not activate extracellular signal-regulated kinase (Erk) and downstream kinases in ABKO myocytes, and basal Erk activity was lower in the intact ABKO heart. In female ABKO mice, heart size was normal, even after ovariectomy. Male ABKO mice had reduced exercise capacity and increased mortality with pressure overload. Thus, alpha(1)-ARs in male mice are required for the physiological hypertrophy of normal postnatal cardiac development and for an adaptive response to cardiac stress.

Animals↗
PubMed2002

Prospective validation of an echocardiographic index for determining the severity of chronic mitral regurgitation.

The aim of this study is to prospectively validate a recently reported semiquantitative index of mitral regurgitation (MR) severity. MR is a common echocardiographic finding with no single reference standard to evaluate its severity. We recently developed and retrospectively tested a semiquantitative index of MR severity. The MR index is a composite of 6 echocardiographic variables: jet penetration, proximal isovelocity surface area, continuous-wave Doppler characteristics of the regurgitant jet, pulmonary artery pressure, pulmonary venous flow pattern, and left atrial size. Sixty-two consecutive patients with varying grades of MR were prospectively studied. Patients were divided into 3 groups for comparison: mild MR, moderate MR, and severe MR. Each patient was evaluated for the 6 variables, with each variable scored on a 4-point scale (0 to 3). The reference standards for MR severity were qualitative evaluation by an expert, measurement of the regurgitant fraction (RF), and the effective regurgitant orifice area. The MR index increased in proportion to MR severity with a significant difference among the 3 groups (F = 84; p <0.0001). The MR index also correlated with RF (r = 0.73; p <0.0001) and the effective regurgitant orifice area (r = 0.74; p = 0.0001). A MR index > or = 2.2 identified 13 of 16 patients with severe MR (sensitivity 82%, specificity 98%, positive predictive value 93%). No patient with severe MR had a score <2.0 and no patient with mild MR had a score >1.67. These results concurred with those obtained in a previously published retrospective study. Thus, the MR index is a simple, reproducible semiquantitative estimate of MR severity, that is widely applicable in routine clinical practice.

Adult↗
PubMed2002

Effects of long-term biventricular stimulation for resynchronization on echocardiographic measures of remodeling.

BACKGROUND: Long-term ventricular resynchronization therapy improves symptom status. Changes in left ventricular remodeling have not been adequately evaluated. METHODS AND RESULTS: Fifty-three patients with systolic heart failure and bundle-branch block underwent implantation of biventricular stimulation (BVS) devices as part of a randomized trial. Echocardiograms were acquired at randomization and at 6-week intervals until completion of 12 weeks of continuous BVS. There were no changes in heart rate or QRS duration after 12 weeks of BVS. Serum norepinephrine values did not change with BVS. After 12 weeks of BVS, left atrial volume decreased. Left ventricular end-systolic and end-diastolic dimensions and left ventricular end-systolic volume also decreased after 12 weeks of BVS. Sphericity index did not change. Measures of systolic function, including left ventricular outflow tract and aortic velocity time integral and myocardial performance index, improved. CONCLUSIONS: Long-term resynchronization therapy results in atrial and ventricular reverse remodeling and improved hemodynamics.

Adult↗
PubMed2002

Anticoagulation during pregnancy.

Anticoagulation of a pregnant woman is a complex issue for both the treating physician and the patient. In patients with mechanical prosthetic valves, long-term anticoagulation is mandatory to prevent thromboembolic complications; and in those with thrombophilic disorders and history of thromboembolism, anticoagulation is strongly indicated. With an increase in the number of patients with prosthetic heart valves, as well as the increase in maternal age, the issue of anticoagulation has become a very important one. Despite the widespread use of warfarin and unfractionated heparin during pregnancy, the optimal use of anticoagulants during pregnancy remains controversial because of a lack of appropriate prospective randomized clinical trials. In fact, even retrospective data on heparin provide miserably inadequate information for those making a decision on the correct dosing regimen. More recently, low molecular weight heparin has been proposed as a safer method of anticoagulation. This review summarizes current data and recommendations on anticoagulation during pregnancy.

Adult↗