Off pump coronary artery bypass (OPCAB) in critical left mainstem stenosis—Our experience

Background Beating heart surgery has now become the commonest technique of doing Coronary Artery Bypass Graft Surgery (CABG) in our country. It is being used even in such high risk situations like diffuse coronary disease and Critical Left Main stem Stenosis (LMCS) with good results. The aim of this study is to retrospectively review our results in Off-Pump Coronary Artery Bypass Surgery (OPCAB) in patients with critical left main stem stenosis. Methods This study is a retrospective analysis of the data of patients who underwent primary coronary artery bypass surgery. During the period from April 2003 to September 2005 a total of 64 patients underwent OPCAB procedure for critical LMCS. During the same period 10 patients underwent CABG on Cardio Pulmonary Bypass (CPB). The age range was 36–77yrs. The sex distribution was M: F 53∶10. Ten patients were done as emergency. 2 of them were on Intra Aortic Balloon Pump (IABP) support preoperatively. 10 patients were high risk with a Euro score of ≥5. Results Left Internal Mammary Artery (LIMA) was used in 78% of cases. Average grafts per patient was 2.96. The median ventilation time was 5.91 hrs. New IABP insertion in postoperative period was required in 1 patient. One patient was reexplored for bleeding. There was one perioperative myocardial infarction. 57% of patients did not need any blood transfusion. There was no conversion to CPB. There was no operative mortality. Inotropes were used in ten cases. Conclusions OPCAB is a safe method of revascularization in patients with critical LMCS. Preoperative IABP is useful in patients with cardiogenic shock. However, there is a place for CPB in patients needing additional procedures like Mitral Valve repair (MV repair) or Dor's procedure or when the vessels are very diffusely diseased. Those patients who are unstable despite IABP support may be managed by Beating heart On Pump (BHOP) technique.     

Spontaneous transpyloric passage and performance of 'fine bore' polyurethane feeding tubes: a controlled clinical trial

Certain groups of patients requiring enteral nutritional support are at increased risk of regurgitation and pulmonary aspiration of feed. Positioning of enteral feeding tubes distal to the pylorus has been advocated as a method of reducing such complications. Various techniques have been suggested to achieve postpyloric siting. Reports have indicated that lengthening the tube or altering the distal end tip configuration, by varying the tip profile or by the addition of a weight, may facilitate spontaneous transpyloric passage of the tube. This prospective controlled clinical study using three new polyurethane tubes demonstrates that the frequency of spontaneous transpyloric passage of the tube is not affected by tip profile or by the addition of a weight. Indeed, with all three tube designs only about one-third had passed spontaneously through the pylorus at 24 hr. Once through the pylorus the unweighted tube stayed in position significantly longer than the weighted tubes (p less than 0.005). We suggest that in those patients requiring post-pyloric feeding, endoscopic or fluoroscopic techniques should be used to position the tubes at the time of insertion, and that an unweighted tube should be used to prolong tube usage.     

The role of the high dependency unit in postoperative care: an update.

The current experience of a high dependency unit established 5 years ago for the postoperative care of high-risk patients undergoing surgery is reported. The resource implications and contributions to the safety and quality of post-operative care, particularly pain relief, are described.     

Structure of the reaction center from Rhodobacter sphaeroides R-26: the cofactors.

The three-dimensional structure of the cofactors of the reaction center of Rhodobacter sphaeroides R-26 has been determined by x-ray diffraction and refined at a resolution of 2.8 A with an R value of 26%. The main features of the structure are similar to the ones determined for Rhodopseudomonas viridis [Michel, H., Epp, O. & Deisenhofer, J. (1986) EMBO J. 5, 2445-2451]. The cofactors are arranged along two branches, which are approximately related to each other by a 2-fold symmetry axis. The structure is well suited to produce light-induced charge separation across the membrane. Most of the structural features predicted from physical and biochemical measurements are confirmed by the x-ray structure.     

Sites in the male primate brain at which testosterone acts as an androgen

Quantitative autoradiographic analysis was used to identify regions in the brain of the male primate where androgen binding sites may be involved in the actions of testosterone. Three days after castration, adult male rhesus monkeys received a subcutaneous injection of either dihydrotestosterone propionate (DHTP, 20 mg, n = 6), testosterone propionate (TP, 100 mg, n = 2), or oil vehicle (control males, n = 4). Three hours later, 5 mCi [3H]testosterone was administered as an i.v. bolus. At 60 min, brains were rapidly removed and the left halves were used for autoradiography. In control males, highest percentages of labeled neurons (20-84% using a rigorous Poisson criterion) were observed in the ventromedial, arcuate and premammillary nuclei (n.) of the hypothalamus, medial preoptic n., bed n. of stria terminalis, intercalated mammillary n., lateral septal n. and the medial, cortical and accessory basal n. of the amygdala. Pretreatment with DHTP eliminated labeling in androgen target tissues of the genital tract, and reduced the percentages of labeled neurons to 4-22% of control values in the arcuate, lateral septal, premammillary and intercalated mammillary n., indicating that in these regions testosterone acted predominantly at androgen binding sites. However, in the medial preoptic n., the ventromedial hypothalamic n. and the accessory basal amygdaloid n., DHTP pretreatment resulted in much less blocking which, together with other data, suggested that in these sites, testosterone's actions involved aromatization and interaction with estrogen-binding sites.     

Stimulation of Alpha-Adrenoceptors Facilitates the Release of Growth Hormone-Releasing Hormone from Rat Hypothalamus in vitro

While extensive evidence suggests that adrenoceptors play an important role in the control of growth hormone in the rat, there are few studies involving the direct measurement of growth hormone-releasing hormone (GHRH). We have therefore developed a radioimmunoassay for rat GHRH, and used it to investigate the modulation of GHRH release by noradrenaline from incubated rat hypothalamus in vitro. The GHRH radioimmunoassay had no significant cross-reactivity with other hypothalamic or GHRH-related peptides, and was sensitive to 4 pg/tube; intra- and interassay coefficients of variation were 6% and 12% respectively. Single incubated rat hypothalami produced a stable and readily measurable output of GHRH in successive 20 min incubations after an initial 60 min preincubation; the release of GHRH was increased in the presence of 56 mM KCI, but did not respond to KCI-depolarization when calcium was excluded from the medium. Stimulated GHRH release was identical to synthetic rat GHRH(1–43) on high-performance liquid chromatography and Sephadex G-75 chromatography.
Noradrenaline stimulated GHRH secretion in a dose-dependent manner in the concentration range 10⁻¹⁰— 10⁻⁶M, with a plateau in response at 10⁻⁷M. Stimulation with noradrenaline 10⁻⁷M was blocked by idazoxan 10⁻⁵M and attenuated by thymoxamine 10⁻⁵M, but was unaffected by timolol 10⁻⁵M. Both the α₂-adrenoceptor agonist guanfacine, and the α₁-adrenoceptor agonist methoxamine, specifically stimulated GHRH secretion.
It is concluded that noradrenaline stimulates the release of GHRH at both α₁ and α₂-adrenoceptors.