William C Feng

Alpert Medical School - Brown University, Providence, Rhode Island, United States

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Publications (4)9.66 Total impact

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    ABSTRACT: We studied the contractile response of human peripheral microvasculature to thromboxane A-2 (TXA-2) before and after cardiopulmonary bypass (CPB), with and without the blockade of TXA-2 receptors, or the inhibition of phospholipase C (PLC), phospholipase A-2 (PLA-2) or protein kinase C (PKC)-α. We also examined the protein/gene expression and localization of TXA-2 receptors, TXA-2 synthase, PLC, and other TXA-2-related proteins. Skeletal muscle arterioles (90-180 μm in diameter) were harvested pre- and post-CPB from patients (n = 28) undergoing cardiac surgery. The post-CPB contractile response of skeletal muscle arterioles to TXA-2 analog U-46619 was impaired compared with pre-CPB (P < .05). The presence of TXA-2 receptor antagonist SQ-29548 (10(-6)mol/L) prevented the contractile response to U-46619 (P < .05). Pretreatment with the PLC inhibitor U-73122 (10(-6)mol/L) significantly inhibited the U-46619-induced contractile response (P < .01). Administration of the PLA-2 inhibitor quinacrine (10(-6)mol/L) or PKC-α inhibitor safingol (2 × 10(-5)mol/L), however, failed to affect U-46619-induced contraction. Total protein levels and gene expression of TXA-2 receptors, and TXA-2 synthase of skeletal muscle, were not altered post-CPB. Confocal microscopy showed no differences in the expression of PLCβ-3 in the microcirculation. PLCβ-3 was localized to both smooth muscle and endothelium. CPB decreases the contractile response of human peripheral arterioles to TXA-2 soon after cardiac surgery. This response may be in part responsible for the decrease in vascular tone, and accompanying hypotension sometimes observed after cardiac operations utilizing CPB.
    Full-text · Article · Aug 2011 · Surgery
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    ABSTRACT: Cardiac reoperations are challenging and time-consuming and incur a high incidence of perioperative complications because of injuries to cardiac structures, bleeding, and hemodynamic instability. Some centers are using extracorporeal circulation with heparinization at the time of resternotomy, but it leads to prolonged anticoagulation, platelet dysfunction, fibrinolysis, coagulopathy, and morbidity. The authors routinely perform resternotomy in complex surgery with the support of heparinless cardiopulmonary bypass with heparin-bonded circuits (HBCs). The authors describe their technique, indication, and results. The femoral artery or axillary artery and femoral veins are cannulated before sternotomy, and cardiopulmonary bypass is instituted using an HBC without systemic heparinization. Systemic heparin (200-300 U/kg) is administered when all structures are isolated before aortic cross-clamping (activated coagulation time >400 seconds). Between 1996 and 2008, 336 patients underwent redo sternotomy using the HBC for complex cardiac procedures, with 29 deaths (8.6% deaths within 30 days). Only 5 (1.5%) of 336 patients sustained injury to the right ventricle, aorta, bypass grafts, or ventricular fibrillation during re-entry without hemodynamic deterioration; and underwent uneventful repair and outcomes. There was no online HBC thrombosis. This study shows that HBC without systemic heparinization during resternotomy can be used safely in complex redo cardiac surgery. The heart is completely decompressed during the resternotomy, allowing easy dissection, less likely injury to vital structures, and less bleeding without compromising the hemodynamics.
    No preview · Article · Apr 2011 · Journal of cardiothoracic and vascular anesthesia

  • No preview · Article · Apr 2011 · The Journal of thoracic and cardiovascular surgery
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    Dionisios Vrochides · William C Feng · Arun K Singh
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    ABSTRACT: During the last 5 years, postoperative Pseudomonas mediastinitis has occurred in 2 of the 3,072 patients in our institution who have undergone cardiopulmonary bypass cardiac operations via a sternotomy. To our knowledge, there is no prior report in the English-language literature of postoperative Pseudomonas mediastinitis that originated at the aortic cannulation site, yet that was the site of origin in both of these patients. The 1st patient developed a mycotic pseudoaneurysm of the ascending aorta at the cannulation site, secondary to the development of Pseudomonas mediastinitis following aortic valve replacement. This sequela was successfully treated by means of aneurysmectomy and closure of the aorta with a bovine pericardial patch, under cardiopulmonary bypass with circulatory arrest. The 2nd patient developed pseudoaneurysm and perforation of the aorta at the cardioplegia needle site, secondary to Pseudomonas mediastinitis following aortic and mitral valve replacement. This patient died. In both patients, the cannulation site and the cardioplegia needle site had been closed with pledgeted sutures. Pseudomonas aeruginosa was cultured from both sites. Once the diagnosis of Pseudomonas mediastinitis is made following heart surgery, the patient should undergo reoperation, if possible, for removal of the foreign bodies (pledgeted sutures). In addition, these patients should be monitored with chest magnetic resonance angiography every 3 months for 1 year, in order to diagnose early development of a mycotic pseudoaneurysm and subsequent complications.
    Full-text · Article · Feb 2003 · Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital