Faculty Bibliography

OBJECTIVE:The optimal anticoagulant therapy during pregnancy in women with mechanical heart valves remains controversial. This study highlights a case of high-dose warfarin ingestion throughout pregnancy and performed a systematic review to assess rates of teratogenicity with high versus low warfarin dosing (≤5 mg daily). METHODS:A literature search for all case reports and available literature was conducted in PubMed, Medline, and EMBASE up to December 2016 using medical subject heading terms "mechanical prosthetic valves," "pregnancy," "oral anticoagulants," "warfarin," "coumarins," "heparin, low-molecular-weight," and "thromboembolism." To be included, warfarin had to be administered anytime between 6 and 12 weeks of gestation with the dose being specified. The Newcastle-Ottawa Scale was used to assess quality of the cohort data. RESULTS:The woman in the studied case received the highest reported warfarin doses throughout pregnancy (14.5-16.5 mg daily) and delivered a baby with no evidence of teratogenicity to the current age of 5 years. The study identified 23 case reports, with all demonstrating warfarin teratogenicity regardless of high-dose (n = 12) or low-dose (n = 11) warfarin. Twelve cohort studies identified a warfarin teratogenicity rate of 5.0%, with rates of 2.4% and 10.5% with low- and high-dose warfarin, respectively. Risk of bias was moderate (median Newcastle-Ottawa Scale score of 6) for all of the cohort studies. CONCLUSION/CONCLUSIONS:Although a lower prevalence of warfarin-induced teratogenicity is reported with low-dose warfarin, a safe "cut-off" dose is misleading. Teratogenic risk with warfarin is unpredictable, mandating individual decisions regardless of the dose.

Canadian practice guidelines for nonvalvular atrial fibrillation (NVAF) recommend that most patients receive a novel oral anticoagulant (NOAC) in preference to warfarin to prevent stroke, but not all patients have insurance that covers NOACs. The gap between optimal therapy and drug coverage is unknown. We retrospectively assessed eligibility for NOACs in patients with NVAF at our single-centre anticoagulation clinic and ascertained whether provincial drug coverage would be in place. Most patients (89%-95%) were eligible, but only 39%-41% qualified for drug coverage. Our findings suggest most Albertans with NVAF might not have drug coverage for optimal medical therapy for stroke prevention.

The nature of memory is a central issue in neuroscience. How does our representation of the world change with learning and experience? Here we use the transcription of Arc mRNA, which permits probing the neural representations of temporally separated events, to address this in a well characterized odor learning model. Rat pups readily associate odor with maternal care. In pups, the lateralized olfactory networks are independent, permitting separate training and within-subject control. We use multiday training to create an enduring memory of peppermint odor. Training stabilized rewarded, but not nonrewarded, odor representations in both mitral cells and associated granule cells of the olfactory bulb and in the pyramidal cells of the anterior piriform cortex. An enlarged core of stable, likely highly active neurons represent rewarded odor at both stages of the olfactory network. Odor representations in anterior piriform cortex were sparser than typical in adult rat and did not enlarge with learning. This sparser representation of odor is congruent with the maturation of lateral olfactory tract input in rat pups. Cortical representations elsewhere have been shown to be highly variable in electrophysiological experiments, suggesting brains operate normally using dynamic and network-modulated representations. The olfactory cortical representations here are consistent with the generalized associative model of sparse variable cortical representation, as normal responses to repeated odors were highly variable (∼70% of the cells change as indexed by Arc). Learning and memory modified rewarded odor ensembles to increase stability in a core representational component.

BACKGROUND:Cardiac rhythm monitoring is widely applied on hospitalized patients. However, its value has not been evaluated systematically. METHODS:This study considered the utility of our institutional telemetry guidelines in predicting clinically significant arrhythmias. A retrospective analysis was performed of 562 patients admitted to the telemetry unit. A total of 1932 monitoring days were evaluated. Patients were divided into 2 groups based on telemetry guidelines: "telemetry indicated" and "telemetry not indicated". RESULTS:Differences in arrhythmia event rates and pre-defined clinical significance were determined. One hundred and forty-four (34%) vs. 16 (11%) patients had at least one arrhythmic event in the "telemetry indicated" group compared with the "telemetry not indicated" group, respectively (P = 0.001). No patient in the "telemetry not indicated" group had a clinically significant arrhythmia. In contrast, of patients in the "telemetry indicated" group who had at least one arrhythmic event, 36% were considered clinically significant (P < 0.05). CONCLUSION/CONCLUSIONS:In conclusion, this study validates and supports the use of our institutional telemetry guidelines to allocate this resource appropriately and predict clinically significant arrhythmias.

Acute myocardial infarction (AMI) in patients with immune thrombocytopenic purpura (ITP) is rare. We describe a case of AMI in patient with ITP. An 81-year-old woman presented with acute inferoposterior MI with low platelet count on admission (34,000/µl). Coronary angiography revealed significant mid right coronary artery (RCA) stenosis with thrombus, subsequently underwent successful percutaneous coronary intervention (PCI). In some patients with immune thrombocytopenia purpura and acute myocardial infarction, percutaneous coronary intervention is a therapeutic option.

Telemetry monitoring is a limited resource in most hospitals. Few clinical studies have established firm criteria for inpatient telemetry. At our urban institution, we have developed and incorporated guidelines to identify patients who benefit from cardiac rhythm monitoring. These guidelines serve to minimize inappropriate use of telemetry beds, thereby preventing emergency department overcrowding and ambulance diversion. This improvement in efficiency is achieved without compromising health care.