OPCAB therapy survey: off-pump clopidogrel, aspirin or both therapy survey.

BACKGROUND: Standards for heparinization during off-pump coronary artery bypass (OPCAB) are lacking. Similarly, there are no established standards for antiplatelet therapy before or after OPCAB. The aim of this study was to determine current practices and standards for both antiplatelet and heparin therapy in OPCAB. METHODS: A postal, multiple-choice survey questionnaire was sent to 800 randomly chosen cardiothoracic surgeons in the United States and Canada. Responses were tabulated and analyzed. RESULTS: The overall response rate was 38% (304 surgeons). The respondents performed CABG in centers with an overall volume between 240 and 1,250 procedures per year (average 380 procedures per year). OPCAB procedures within the same institutions ranged from 20 and 375 cases per year. Sixteen percent (48) of the respondents routinely administer antiplatelet therapy preoperatively; of these, 18% (9) use clopidogrel (Plavix) and 65% (31) aspirin. Eighty-eight percent (267) of the respondents routinely administer antiplatelet therapy after OPCAB. Of these, 24% (65) use clopidogrel and 74% (197) aspirin. Anticoagulation protocols during OPCAB were more variable with 28% (85) administering full dose of heparin, 54% (164) administering half dose heparin, and 13% (40) administering 1/3 dose of heparin during construction of coronary anastomoses. Although 10% (30) maintain an activated clotting time (ACT) above 400 seconds, 70% (213) are content with an ACT above 300 seconds and less than 400 seconds, and 20% (61) responded as "other". The average blood shed postoperatively was 600 ml (range 300 ml and 1 liter). Forty percent (122) administer protamine at half dose, and 60% (182) administer a full dose. CONCLUSION: Although the vast majority of surgeons use antiplatelet therapy postoperatively, a minority administer preoperative antiplatelet agents for OPCAB. The majority of surgeons use a half dose of heparin during OPCAB with ACT maintained above 300 seconds (> 80%). Prospective studies are necessary to determine the short and intermediate effects of antiplatelet therapy and heparinization doses in OPCAB surgery.

Lateral hypothalamic NMDA receptors and glutamate as physiological mediators of eating and weight control.

To determine whether endogenous lateral hypothalamic (LH) glutamate and its N-methyl-D-aspartate (NMDA) receptors might participate in the stimulation of natural eating, LH injection of the NMDA antagonist D-(-)-2-amino-5-phosphonopentanoic acid (D-AP5) was tested in adult male rats for suppressive actions on feeding elicited by 1) NMDA, kainic acid or D, L-alpha-amino-3-hydroxy-5-methylisoxazole (AMPA) injected into the LH; 2) food deprivation; and 3) the onset of the nocturnal period. D-AP5 (10-100 nmol) reduced by 72-90% the approximately 10-g eating response elicited by NMDA (10 nmol) without affecting the quantitatively similar eating responses elicited by kainic acid (1.0 nmol) or AMPA (1.0 nmol). This treatment also suppressed deprivation-induced eating by as much as 61% and nocturnal eating by as much as 40%. To determine its long-term effects, D-AP5 (50 nmol) was injected bilaterally into the LH twice a day for 8 consecutive days. This treatment caused up to 65% reductions in daily food intake and body weight loss of up to 13 g/day. These findings, showing behaviorally selective suppressions of eating and body weight by D-AP5, argue that endogenous LH glutamate acts to regulate natural eating and body weight and that NMDA receptors participate in these functions.

The lateral hypothalamus: a primary site mediating excitatory amino acid-elicited eating.

Lateral hypothalamic (LH) injections of the excitatory neurotransmitter glutamate, or its excitatory amino acid (EAA) agonists, kainic acid (KA), D,L-alpha-amino-3-hydroxy-5-methyl-isoxazole propionic acid (AMPA), or N-methyl-D-aspartic acid (NMDA), can rapidly elicit an intense feeding response in satiated rats. To determine whether the LH is the actual locus of this effect, we compared these compounds' ability to stimulate feeding when injected into the LH, versus when injected into sites bracketing this region. Food intake in groups of adult male rats was measured 1 h after injection of glutamate (30-900 nmol), KA (0.1-1.0 nmol), AMPA (0.33-3.3 nmol), NMDA (0.33-33.3 nmol) or vehicle, through chronically implanted guide cannulas, into one of seven brain sites. These sites were: the LH, the anterior and posterior tips of the LH, the thalamus immediately dorsal to the LH, the amygdala just lateral to the LH, or the paraventricular and perifornical areas medial to the LH. The results show that across doses and agonists the eating-stimulatory effects were largest with injections into the LH. In the LH, glutamate between 300 and 900 nmol elicited a dose-dependent eating response of up to 5 g within 1 h (P < 0.01). Each of the other agonists at doses of 3.3 nmol or less elicited eating responses of at least 10 g with injections into this site. Injections into the other brain sites produced either no eating, or occasionally smaller and less consistent eating responses.(ABSTRACT TRUNCATED AT 250 WORDS)