Cardiac imaging in the evaluation of patients presenting to the emergency department with chest pain

Conclusions  Despite the utility and benefits that each imaging modality has to offer, it is easy to see why there is still no perfect choice for a noninvasive cardiac imaging modality to assist in the management of chest pain patients. All of the current imaging techniques have their own significant strengths and weaknesses when compared with other modalities. SPECT and echocardiography are wellestablished technologies that can directly assess the presence of myocardial ischemia and its functional consequence on RF; newer and more expensive techniques such as MDCT and CMR can directly assess coronary anatomy and have just started to be evaluated in the acute chest pain setting. There are no studies that directly compare these technologies, and more data are clearly needed before the question of whether anatomic imaging versus perfusion/function imaging is the better approach can be answered. Other comparisons such as relative safety, availability, logistics, and cost-effectiveness between the various technologies are also lacking. Of all of the imaging modalities discussed, MCE is the only portable technology. The images do not require expensive software or other technology for offline processing before interpretation, and any trained cardiologist can read the study at the bedside or, potentially, over the Internet, providing near-instantaneous results in the acute cardiac setting, where time is of the essence. MCE is also relatively cheap compared with other technologies, a potential advantage for payors but not necessarily for payees. How reimbursement rates and fee structures eventually affect clinical practice is also unknown. Despite these and other questions that need to be answered before any one technique will be used exclusively, the future of noninvasive cardiac imaging remains an exciting and ever-changing field. The adaptation of any one of these techniques into its proper role in the ED Journal of Nuclear Cardiology Wyrick and Wei 753 Volume 13, Number 6;749-55 Cardiac imaging in patients with chest pain will take considerably more time and effort in terms of research, money, and time-tested clinical experience.     

REPERFUSION FOLLOWING MYOCARDIAL ISCHAEMIA ENHANCES INOSITOL PHOSPHATE RELEASE IN THE ISOLATED PERFUSED RAT HEART

1. Global myocariial ischaemia (MI) for periods greater tan 5 min caused an inhibition of phosphatidylinositol specific phospholipase C (PtdIns-PLC) activity. 2. Two min reperfusion following a 20 min MI period, a time point associated with reperfusion-induced arrhythmias, resulted in an activation of PtdIns-PLC activity, dependent on endogenous noradrenaline and mediated via al-adrenoceptors. 3. This 2 min reperfusion response, in contrast to healthy myocardium, resulted in: (i) enhanced PtdIns-PLC activity; (ii) increased sensitivity to endogenous noradrenaline; (iii) rapid increases in inositol(1,4,5)trisphosphate (Ins(1,4,5)P3); and (iv) PLC hydrolysis primarily of PtdIns(4,5)P₂, such that the majority of InsP isomers derive from Ins(1,4,5)P₃. 4. Together, these data suggest a functional role for Ins(1,4,5)P3 under postischaemic reperfusion conditions, and provide a possible link between al-adrenoceptor stimulation of the PtdIns turnover pathway and reperfusion injury.     

Salvage therapy for prostate cancer recurrence after radiation therapy

Radiotherapy has been successful in treating localized prostate cancer; however, a subset of patients will experience disease recurrence. Determination of the recurrence location must be made using pretreatment and posttreatment clinical variables, imaging, and postradiotherapy biopsy. Patients presumed to have local-only recurrence, optimal clinical risk factors, and an extended life expectancy may be considered for salvage local treatment. Current options include salvage surgery, cryoablation, and brachytherapy. Although they are associated with higher morbidity than primary therapy, salvage treatments can be effective and can still provide patients with a good oncologic and functional outcome. As these modalities continue to improve and patient selection is optimized, better results will evolve.     

T wave amplitude as a quantitative index of regional myocardial sympathetic responsiveness

Alterations in T wave morphology have been quantitated in seven open chest anesthetized dogs by simultaneous recording of electrograms from 10 epicardial sites across the anterior left ventricular wall under basal conditions, following left sympathetic stimulation (LSS) at 2, 4, 8, 12, and 16 Hz and during noradrenaline infusions (NAI) of 0.125, 0.25, 0.50, and 1.0 micrograms/kg/min. Overdrive atrial pacing at 175 beats/min was employed and rate of rise of left ventricular pressure (dP/dt) monitored. Linear log dose-response relationships were found between both peak T amplitude and left ventricular dP/dt for NAI between 0.125 and 0.50 micrograms/kg/min (peak T wave amplitude 4.0 +/- 0.9 to 1.4 +/- 0.7 mV). Following LSS, T wave amplitude responses were highly variable both between animals and between electrode sites in individual studies. A linear log dose-response relationship was found at stimulation frequencies between 8 and 16 Hz (T amplitude 3.9 +/- 1.4 to 1.8 +/- 1.2 mV). Changes in QT interval were minor and inconsistent. It is concluded that changes in peak T wave amplitude may provide a useful index of regional myocardial sympathetic responsiveness following NAI, but are more variable following LSS.     

Age-related changes in centripetal ciliary body movement relative to centripetal lens movement in monkeys

The goal was to determine the age-related changes in accommodative movements of the lens and ciliary body in rhesus monkeys. Varying levels of accommodation were stimulated via the Edinger-Westphal (E-W) nucleus in 26 rhesus monkeys, aged 6–27 years, and the refractive changes were measured by coincidence refractometry. Centripetal ciliary process (CP) and lens movements were measured by computerized image analysis of goniovideographic images. Ultrasound biomicroscopy (UBM) at 50 MHz was used to visualize and measure accommodative forward movements of the ciliary body in relation to age, accommodative amplitude, and centripetal CP and lens movements. At ～3 diopters of accommodation, the amount of centripetal lens movement required did not significantly change with age (p = 0.10; n = 18 monkeys); however, the amount of centripetal CP movement required significantly increased with age (p = 0.01; n = 18 monkeys), while the amount of forward ciliary body movement significantly decreased with age (p = 0.007; n = 11 monkeys). In the middle-aged animals (12–16.5 years), a greater amount of centripetal CP movement was required to induce a given level of lens movement and thereby a given level of accommodation (p = 0.01), compared to the young animals (6–10 yrs). Collectively, the data suggests that, with age, the accommodative system may be attempting to compensate for the loss of forward ciliary body movement by increasing the amount of centripetal CP movement. This, in turn, would allow enough zonular relaxation to achieve the magnitude of centripetal lens movement necessary for a given amplitude of accommodation.     

The effects of paracetamol (acetaminophen) on hepatic tests in patients who chronically abuse alcohol – a randomized study

Aliment Pharmacol Ther 2010; 32: 478–486

Summary

Background Retrospective accounts suggest that therapeutic doses of paracetamol can produce severe hepatic injury in patients with putative high‐risk conditions, including alcoholism and infectious hepatitis. Metabolism of paracetamol to its hepatotoxic metabolite is enhanced in patients who abuse alcohol, who also have compromised liver defences from depressed hepatic glutathione. Aim To determine the effect of paracetamol on serum liver tests of newly abstinent subjects who abuse alcohol, including subjects with hepatitis C infection. Methods A randomized, double‐blind, placebo‐controlled study. Adult alcohol abusers with a current drinking episode longer than 7 days received either placebo or paracetamol 4 g/day for 5 days. Results Of 142 subjects enrolled, 74 received paracetamol and 68 received placebo. Mean ALT activity during treatment increased from 48 to 62 IU/L in the paracetamol group and from 47 to 49 IU/L in the placebo group. Maximum ALT was 238 and 249 IU/L in the paracetamol and control groups respectively. The INR remained unchanged and serum bilirubin decreased in both groups. Subgroup analyses for subjects with alcoholic hepatitis, hepatitis C virus antibody and other subgroups showed no statistical difference between groups. Conclusion Administration of paracetamol 4 g/day appears safe in newly abstinent patients who abuse alcohol.     

Increases in plasma beta-endorphin concentrations during exercise do not contribute to increases in heart rate following autonomic blockade in man.

1. Intrinsic heart rate (IHR: heart rate following autonomic blockade with atropine and propranolol) increases with exercise. The opioid antagonist naloxone has been shown to decrease IHR at rest, raising the possibility that increases in IHR with exercise are beta-endorphin related, since beta-endorphin concentrations have also been shown to rise during exercise. 2. We examined the effects of naloxone (10 mg) on IHR and plasma beta-endorphin levels during aerobic exercise in eight healthy, male subjects in a single blind, crossover study. 3. IHR increased with 25 min bicycling from 97.1 +/- 1.4 to 129.7 +/- 1.2 beats min-1 (mean +/- s.e. mean). This rise was not affected by administration of naloxone. 4. Plasma beta-endorphin concentration rose from 31.1 +/- 3.8 to 94.9 +/- 23.9 pg ml-1 after 25 min exercise. This exercise-induced rise in beta-endorphin concentration was further increased (P less than 0.05) in the presence of naloxone. 5. Our results confirm a rise in IHR and beta-endorphin concentrations with acute exercise but indicate that the changes in IHR are not endorphin-related.     

Sporadic diffuse corneal endotheliitis

We studied two patients with acute diffuse corneal endotheliitis who had no family history of the disease. Endothelial specular photographs taken during and after an attack of endotheliitis demonstrate the deposition of inflammatory material on edematous endothelial cells, with areas of focal endothelial cell loss that resolved with treatment. These cases are distinctly different than the previously described "idiopathic" primary endotheliitis entities, which have included focal or sectoral areas of corneal edema, corneal edema in association with a migrating rejection line, or diffuse edema occurring as a dominantly inherited condition. No definitive causative agents have been established. It is likely that the disease results from an immune response to autoantigens or antigens from an unidentified viral infection. The pathogenesis may be similar to that of corneal homograft rejection.