Schaff, Hartzell V.

Objective Percutaneous aortic valve implantation within native valve calcium has progressed to clinical use despite the absence of data proving equivalence to complete surgical excision and prosthetic valve replacement. A novel self-expanding sutureless bovine pericardial prosthesis (Sorin Perceval) derived from a proven stented valve has been successfully used in humans recently through an open transaortic approach. We sought to develop a minimally invasive technique for native aortic valve excision and sutureless prosthetic aortic valve replacement using robot assistance. Methods The da Vinci S-HD system was used to open and suspend the pericardium anterior to the phrenic nerve in cadavers. A transthoracic cross-clamp was placed across the midascending aorta, following which a transverse aortotomy was made. The native aortic valve cusps were excised, and annular calcium was removed with robotic instruments. After placement of three guide sutures, the Perceval self-expanding pericardial prosthesis mounted on a flexible delivery system was inserted through a working port and lowered into the aortic annulus. Results Successful implantation of all valves was possible using a 3-cm right second intercostal space working port, along with two additional 1-cm instrument ports. A standard transverse aortotomy was sufficient for examination/debridement of the native aortic valve cusps, sizing of the annulus, and deployment of the nitinol-stented, bovine pericardial prosthesis. Delivery, seating, and stability of the device were easily confirmed above and below the aortic valve annulus using the robotic camera. Conclusions Complete excision of diseased native aortic valve cusps with robot assistance facilitates accurate and reproducible aortic valve replacement using a novel self-expanding sutureless version of a proven bovine pericardial prosthesis. This approach is comparable to the current surgical gold standard and is ready for clinical use as an alternative to percutaneous aortic valve implantation.

Cardiac vasoplegia remains a significant contributor of morbidity and mortality in cardiac surgery patients after cardiopulmonary bypass. Effective therapeutic options for vasopressor-refractory vasoplegia are limited. We report 3 patients in whom we administered high-dose intravenous ascorbic acid (vitamin C), a cofactor for endogenous catecholamine synthesis, to treat vasoplegia refractory to epinephrine, vasopressin, and norepinephrine after surgery requiring cardiopulmonary bypass. Reductions in vasopressor requirements were observed in all 3 patients, and, in 2 patients, norepinephrine was completely discontinued within 24 hours. Ascorbic acid is a novel potential therapeutic option for cardiac vasoplegia that warrants rigorous prospective studies.

Smoking is a major risk factor for failure of coronary artery bypass grafts (CABG). Experiments were designed to determine effects of transdermal nicotine, independent of smoking, on structure and function of CABG. Saphenous veins were placed as CABG in untreated dogs (control) or in dogs treated with transdermal nicotine (one 11-mg or two 22-mg patches/day) for 5 wk. Serum nicotine and plasma nitric oxide were measured. Grafts were removed and prepared for organ chamber studies and histology. Serum nicotine averaged 12.1 and 118.7 ng/ml in the 11 mg/day and 44 mg/day groups, respectively. Plasma nitric oxide was higher in dogs treated with 11 mg/day doses compared with controls. In organ chamber studies, endothelium-dependent relaxations to thrombin and A-23187 and endothelium-independent relaxations to nitric oxide were greatest in grafts from dogs treated with 11 mg/day doses. Intimal thickness of the grafts were similar among groups. However, staining for bone sialoprotein was increased in the media of grafts from the 11 mg/day treatment group. These data suggest that transdermal nicotine in doses comparable and double to those used for conventional smoking cessation treatment in humans does not adversely affect early patency of canine CABG up to 4 wk postoperatively. Transdermal nicotine, however, may increase production of and response to nitric oxide in bypass grafts.

To study the effect of hypoxia on vascular tone in human internal mammary artery (IMA), segments of IMA were suspended in organ chambers and contracted with norepinephrine (at a dose producing 30% of maximal contraction). Exposure of IMA segments with endothelium to hypoxia (partial pressure of oxygen, 38 +/- 4 mmHg) resulted in a transient relaxation (47 +/- 6%) followed by constriction (177 +/- 8%) (n = 14). IMA segments without endothelium exhibited a gradual decrease in tension that almost completely counteracted vasoconstriction. The initial transient endothelium-dependent relaxation could be blocked by indomethacin (10(-6)M) and was associated with a 51% increase in 6-ketoprostaglandin F1 alpha production (n = 22, P < 0.05). The endothelium-dependent contraction to hypoxia could be attenuated by indomethacin (n = 6, P < 0.05) or NG-monomethyl-L-arginine (10(-5)M; n = 9, P < 0.05) and was completely blocked by combination of these agonists (n = 6, P < 0.05). These experiments indicate that on exposure to hypoxia, the human IMA exhibits an initial prostacyclin-mediated relaxation followed by contraction due to the production of a constrictor prostanoid in addition to the inhibition of basal production of endothelium-derived relaxing factor.