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Biomedical subjects

Benjamin Sun

Publications and source records attributed to Benjamin Sun.

8 recordsLinked to original sources
PubMed2006

Initial United States experience with the Paracor HeartNet myocardial constraint device for heart failure.

OBJECTIVE: This study was undertaken to review the initial results and surgical safety data for the US Food and Drug Administration safety and feasibility trial of the Paracor HeartNet (Paracor Medical, Inc, Sunnyvale, Calif.) myocardial constraint device. METHODS: Patients with New York Heart Association functional class II or III heart failure underwent device implantation (n = 21) through a left minithoracotomy. RESULTS: The average age was 53 years (31-72 years). There were 18 men and 3 women, and 17 patients had nonischemic etiology of heart failure. Mean heart failure duration was 8.3 years (1.4-18.8 years). Average ejection fraction was 22% (11%-33%), with an average left ventricular end-diastolic dimension of 74 mm (55-94 mm). Previous medical therapy included angiotensin-converting enzyme inhibitors, beta-blockers, diuretics, digoxin, and aldosterone receptor blockers. At implantation, 17 patients had implantable electronic devices: 1 biventricular pacemaker, 11 biventricular pacemakers with cardioverter-defibrillators, and 5 implantable cardioverter-defibrillators. Patient comorbidities included hypertension in 10 cases, diabetes mellitus in 8, myocardial infarction in 1, and ventricular tachycardia in 8. Mean operative time was 68 minutes (42-102 minutes), and implantation time averaged 15 minutes (5-51 minutes). The average time to ambulation was 1.6 days (1-4 days). The intensive care unit stay averaged 3.3 days (1-16 days), and hospital stay averaged 6.3 days (4-16 days). Atrial fibrillation occurred in 2 patients, and there were 2 in-hospital deaths. CONCLUSIONS: The Paracor device can be implanted in patients with heart failure and reduced left ventricular function with a high degree of success. Significant surgical complications were infrequent. The initial US experience supports the conduct of a randomized, controlled, pivotal trial.

Adult↗
PubMed2006

Labeling of skeletal myoblasts with a novel oxygen-sensing spin probe for noninvasive monitoring of in situ oxygenation and cell therapy in heart.

We report the labeling (internalization) of skeletal myoblasts (SMs) with a novel class of oxygen-sensing paramagnetic spin probe for noninvasive tracking and in situ monitoring of oxygenation in stem cell therapy using electron paramagnetic resonance (EPR) spectroscopy. SM cells were isolated from thigh muscle biopsies of mice and propagated in culture. Labeling of SM cells with the probe was achieved by coincubating the cells with submicron-sized (270 +/- 120 nm) particulates of the probe in culture for 48 h. The labeling had no significant effect on the viability or proliferation of the cells. The SM cells labeled with the probe were transplanted in the infarcted region of mouse hearts. The engraftment of the transplanted cells in the infarct region was verified by using MY-32 staining for skeletal myocytes. The in situ Po(2) in the heart was determined noninvasively and repeatedly for 4 wk after transplantation. The results showed significant enhancement of myocardial oxygenation at the site of cell transplant compared with untreated control. In conclusion, labeling of SM cells with the oxygen-sensing spin probe offers a unique opportunity for the noninvasive monitoring of transplanted cells as well as in situ tissue Po(2) in infarcted mouse hearts.

Animals↗
PubMed2006

Vacuum-assisted apical suction devices induce passive electrical changes consistent with myocardial ischemia during off-pump coronary artery bypass graft surgery.

OBJECTIVE: Off-pump coronary artery bypass graft surgery is common therapy to completely revascularize diseased hearts. In order to graft posterior arteries in this procedure, the heart must be lifted from the chest cavity and manipulated to expose the surgical field using an apical suction device. This suction device may cause unwanted myocardial ischemia. METHODS: In this observational study, we measured myocardial electrical impedance, a parameter that responds to myocardial ischemia, as well as ST-segment changes during off-pump coronary artery bypass graft surgery in 12 patients with two-vessel coronary artery disease undergoing revascularisation of the left anterior descending and the posterior descending coronary arteries. During the posterior descending artery revascularisation phase of the procedure the apical suction device was oriented over the electrodes used to measure myocardial electrical impedance, thus allowing us the opportunity to assess myocardial ischemia in this region of the heart. RESULTS: In these 12 patients, myocardial electrical impedance progressively increased under the suction device during posterior coronary artery revascularisation, suggesting that myocardial ischemia developed in this region of the myocardium. ST-segment changes were negligible while the heart was vertically displaced (and the suction device attached), but increased immediately when the heart was returned to the neutral anatomical position. CONCLUSION: Our data suggest that the apical suction device may cause ischemia while the heart is vertically displaced and electrically disconnected from the body. Under these conditions, ST-segment changes may not detect myocardial ischemia. Myocardial electrical impedance has the potential to reliably detect intraoperative myocardial ischemia under these circumstances.

Coronary Artery Bypass, Off-Pump↗
PubMed2006

Preoperative pulmonary hypertension is associated with postoperative left ventricular dysfunction in chronic organic mitral regurgitation: an echocardiographic and hemodynamic study.

BACKGROUND: Some degree of pulmonary hypertension (PHTN) is common in patients with chronic mitral regurgitation. The aim of this study was to determine whether preoperative PHTN is associated with postoperative left ventricular (LV) dysfunction. METHODS: The study included 79 patients with chronic organic mitral regurgitation. Preoperative and postoperative LV function was assessed by echocardiography. Preoperative and postoperative hemodynamics were evaluated by a pulmonary artery catheter. RESULTS: Pulmonary artery systolic pressure decreased postoperatively (pre 49 +/- 14 vs. post 36 +/- 11 mm Hg, P < .01). Postoperative LV ejection fraction was significantly reduced in patients with preoperative PHTN (pre 61 +/- 11% vs post 49 +/- 12%, P < .01). A stepwise multivariate regression analysis showed that preoperative pulmonary artery systolic pressure and LV end-systolic dimension were independent predictors of postoperative LV ejection fraction (r = -0.53, P < .001, and r = -0.34, P < .05, respectively). CONCLUSION: Preoperative PHTN is associated with postoperative LV dysfunction in patients with chronic organic mitral regurgitation undergoing mitral valve operation.

Chronic Disease↗
PubMed2004

Practical application of human B-type natriuretic peptide as a therapeutic intervention in the perioperative setting.

The use of human B-type natriuretic peptide (BNP, nesiritide) as a therapeutic intervention is now well established for patients with acute decompensated heart failure. Nesiritide mimics the actions of endogenous BNP by binding to and stimulating receptors in the heart, kidney, and vasculature. Postsurgical patients are typically managed with various combinations of vasodilators, diuretics, and inotropes. Many of these therapeutic interventions lack significant proof of efficacy and are potentially deleterious to these patients, despite the acute hemodynamic improvement that results from their use. Use of nesiritide may supplant some of these therapies as an equally efficacious and possibly safer alternative in patients with decompensated heart failure. Nesiritide is a unique, balanced vasodilator that markedly decreases the signs and symptoms of heart failure in perioperative patients, and also may decrease the need for inotropic agents. This review summarizes nesiritide's mechanism of action and addresses special concerns and practical considerations for cardiothoracic surgeons and anesthesiologists. Overall, nesiritide appears to be an effective and safe therapeutic option in perioperative patients with decompensated heart failure.

Acute Disease↗