Manganese-enhanced magnetic resonance imaging in dilated cardiomyopathy and hypertrophic cardiomyopathy

AIMS

The aim of this study is to quantify altered myocardial calcium handling in non-ischaemic cardiomyopathy using magnetic resonance imaging.

METHODS AND RESULTS

Patients with dilated cardiomyopathy (n = 10) or hypertrophic cardiomyopathy (n = 17) underwent both gadolinium and manganese contrast-enhanced magnetic resonance imaging and were compared with healthy volunteers (n = 20). Differential manganese uptake (Ki) was assessed using a two-compartment Patlak model. Compared with healthy volunteers, reduction in T1 with manganese-enhanced magnetic resonance imaging was lower in patients with dilated cardiomyopathy [mean reduction 257 ± 45 (21%) vs. 288 ± 34 (26%) ms, P < 0.001], with higher T1 at 40 min (948 ± 57 vs. 834 ± 28 ms, P < 0.0001). In patients with hypertrophic cardiomyopathy, reductions in T1 were less than healthy volunteers [mean reduction 251 ± 86 (18%) and 277 ± 34 (23%) vs. 288 ± 34 (26%) ms, with and without fibrosis respectively, P < 0.001]. Myocardial manganese uptake was modelled, rate of uptake was reduced in both dilated and hypertrophic cardiomyopathy in comparison with healthy volunteers (mean Ki 19 ± 4, 19 ± 3, and 23 ± 4 mL/100 g/min, respectively; P = 0.0068). In patients with dilated cardiomyopathy, manganese uptake rate correlated with left ventricular ejection fraction (r2 = 0.61, P = 0.009). Rate of myocardial manganese uptake demonstrated stepwise reductions across healthy myocardium, hypertrophic cardiomyopathy without fibrosis and hypertrophic cardiomyopathy with fibrosis providing absolute discrimination between the healthy myocardium and fibrosed myocardium (mean Ki 23 ± 4, 19 ± 3, and 13 ± 4 mL/100 g/min, respectively; P < 0.0001).

CONCLUSION

The rate of manganese uptake in both dilated and hypertrophic cardiomyopathy provides a measure of altered myocardial calcium handling. This holds major promise for the detection and monitoring of dysfunctional myocardium, with the potential for early intervention and prognostication.

The power of subjectivity in competency-based assessment

With the introduction of competency-based undergraduate curriculum in India, a paradigm shift in the assessment methods and tools will be the need of the hour. Competencies are complex combinations of various attributes, many of which being not assessable by objective methods. Assessment of affective and communication domains has always been neglected for want of objective methods. Areas like professionalism, ethics, altruism, and communication—so vital for being an Indian Medical Graduate, can be assessed longitudinally applying subjective means only. Though subjectivity has often been questioned as being biased, it has been proven time and again that a subjective assessment in expert hands gives comparable results as that of any objective assessment. By insisting on objectivity, we may compromise the validity of the assessment and deprive the students of enriched subjective feedback and judgement also. This review highlights the importance of subjective assessment in competency-based assessment and ways and means of improving the rigor of subjective assessment, with particular emphasis on the development and use of rubrics.

Neocortical injury-induced status epilepticus

OBJECTIVE

To characterize neocortical onset status epilepticus (SE) in the C57BL/6J mouse.

METHODS

We induced SE by administering homocysteine 16-18 hours after cobalt (Co) implantation. SE was monitored by video and electroencephalography (EEG). We evaluated brain structure with magnetic resonance imaging (MRI). Neurodegeneration was evaluated 72 hours after SE using Fluoro-Jade C staining.

RESULTS

Cobalt triggered seizures in a dose-dependent manner (median effective dose, ED₅₀  = 0.78 mg) and the latency to peak seizure frequency shortened with increased dose. Animals developed SE after homocysteine administration. SE began with early intermittent focal seizures, consisting of frontal onset rhythmic spike-wave discharges manifested as focal dystonia with clonus. These focal seizures then evolved into generalized continuous convulsive activity. Behavioral manifestations of SE included tonic stiffening, bilateral limb clonus, and bilateral tonic-clonic movements, which were accompanied by generalized rhythmic spike-wave discharges on EEG. After prolonged seizures, animals became comatose with intermittent bilateral myoclonic seizures or jerks. During this period, EEG showed seizures interspersed with generalized periodic discharges on a suppressed background. MRI obtained when animals were in a coma revealed edema, midline shift in frontal lobe around the Co implantation site, and ventricular effacement. Fluoro-Jade C staining revealed neurodegeneration in the cortex, amygdala, and thalamus.

SIGNIFICANCE

We have developed a mouse model of severe, refractory cortical-onset SE, consisting of convulsions merging into a coma, EEG patterns of cortical seizures, and injury, with evidence of widespread neocortical edema and damage. This model replicates many features of acute seizures and SE resulting from traumatic brain injury, subarachnoid, and lobar hemorrhage.

Single-use lidocaine hydrochloride 5 per cent w/v and phenylephrine hydrochloride 0.5 per cent w/v topical spray; can it now be employed as a multi-use atomiser?

OBJECTIVE

This study investigated the risk of contamination of lidocaine hydrochloride 5 per cent w/v and phenylephrine hydrochloride 0.5 per cent w/v topical solution after modification of the application technique.

METHODS

This paper reports a prospective basic sciences study involving 22 study samples and 1 control sample of the lidocaine hydrochloride and phenylephrine hydrochloride topical anaesthetic spray. The samples were assessed for microbiological contamination after a single use on patients using a modified application technique. The modification involves keeping the nozzle (actuator) pressed down whilst withdrawing the spray to at least 30 cm (1 ft) from the patient, before releasing the nozzle (actuator) and subsequently reapplying the spray.

RESULTS

Three of the 23 samples confirmed bacterial growth in the bottle contents, but there was no growth in any of the samples from the pump. These bacteria are considered to be contaminants.

CONCLUSION

There is a potential to use the lidocaine hydrochloride 5 per cent w/v and phenylephrine hydrochloride 0.5 per cent w/v topical solution as a multi-use spray by changing the actuator between patients. This would have significant beneficial cost implications without the attendant infection control risk.

Catheter-induced urethral injury and tubularized urethral plate urethroplasty in such iatrogenic hypospadias

Background

Catheter-induced urethral erosion can involve meatus, glans and any extent of penile shaft. These injuries cause a lot of psychological, social and sexual trauma to the patient. Though the use of condom drainage system can render this spinal cord injury patient effectively dry, but can lead to penile or urethral complications. Many of these patients are kept on indwelling catheter. Long duration catheterization, poor catheter care in such paraplegic patients and other morbid patients may lead to urethral erosions. We conducted a prospective study of catheter-induced urethral injury from July 2014 to February 2016 in our tertiary care centre. The demographics, past history of illness, catheter material, and duration of catheterization, securing of catheter, local examination findings and associated comorbidities were recorded. Factors leading to urethral erosion were evaluated. And patients, who were fit and were willing for surgery, underwent tubularized urethral plate urethroplasty after 4–6-week supra-pubic diversion. The objective of the study was to evaluate factors of urethral erosion, and the results tubularized urethral plate urethroplasty in iatrogenic hypospadias.

Results

We had twelve patients of catheter associated urethral injury in the study period. Age of the patients varied from 34 to 95 years with a mean of 61.25 years. Duration of catheterization ranged from 6 to 24 months with a mean duration 10.9 months. Catheters used were silicon coated, not secured to abdomen and had comorbid condition of neurological or cardiac origin in all patients. Long duration of catheter, poor quality of catheter and poor catheter care such moribund with poor body resistance patients were the main causative factor for urethral erosion. Urethral injuries varied from erosion of distal 2 cm to entire ventral urethra till penoscrotal junction with or without penile torque. Six of these patients underwent tubularized urethral plate urethroplasty with good cosmetic and functional postoperative outcome.

Conclusion

Patients of spinal cord injury, patients with comorbid condition like diabetes mellitus and ischaemic heart disease, poor catheter care and long duration catheterization are likely to have severe urethral injury. Extent of injury may vary from meatal erosion to erosion of entire ventral urethra till penoscrotal junction leading to iatrogenic hypospadias. These patients either may be put on clean intermittent catheterization or supra-pubic catheterization. Results of tubularized urethral plate urethroplasty in such iatrogenic hypospadias are very good.

Imaging aortic valve calcification: significance, approach and implications

Aortic stenosis is the most prevalent valvular heart disease worldwide, and rates are increasing with the growing and more elderly population. Although the precise mechanisms that underpin aortic valve stenosis are incompletely understood, pathological valvular calcification has emerged as a key instigator in mediating the biomechanical stiffening that can lead to symptoms, the need for aortic valve replacement, and death if left untreated. Here, we review the currently understood processes leading to aortic valve calcification, summarise the contemporary imaging assessments of valve calcification, and highlight how these might improve patient care and accelerate our pathological understanding and the development of an effective medical therapy.

SAT-483 Levothyroxine Absorption Test: A Potential Therapeutic Tool for Levothyroxine Malabsorption

INTRODUCTION

Persistent hypothyroidism (PH) even on high doses of levothyroxine is a common clinical problem and it is difficult to treat. Levothyroxine absorption test has been used to distinguish between pseudo-malabsorption and malabsorption as one of its causes. This test uses 1000 mcg of levothyroxine to calculate the percentage of levothyroxine absorbed. We present a case of malabsorption in which we used the levothyroxine absorption test to diagnose as well as treat malabsorption.

Case:

55-year-old male with history of papillary thyroid cancer status post total thyroidectomy, postsurgical hypothyroidism, recurrent small bowel obstruction, status post jejunal resection, complicated by high output entero-cutaneous fistula, distal high-grade obstruction status post placement of jejunal tube, chronic abdominal pain on narcotics, who initially presented with sepsis and was also found to be hypothyroid.

The thyroid stimulating hormone (TSH) level was 45.25 with free thyroxine (FT4) level of 0.54. He was adherent to his levothyroxine (LT4) 175 mcg once daily which is given one hour after tube feeds have been stopped or one hour prior to any administration of other medications.

Levothyroxine absorption test was done to distinguish between malabsorption versus pseudo-malabsorption. Three different doses of LT4 were used with results all consistent with malabsorption. The percentage of absorption with 175 mcg, 500 mcg, and 1000 mcg LT4 were 3.4%, 7.2%, and 18% respectively. The formula used to determine the percentage of absorption was (total T4 at 2 hour after LT4 administration - baseline total T4 prior to administration in mcg/L) x plasma volume in liter/dose of administered LT4 in mcg. The final prescription dose of 700 mcg once daily was then derived from the available data, which eventually corrected the patient’s hypothyroidism. Repeat testing after 2 weeks showed TSH of 0.17, FT4 of 1.29 and total T4 of 6.5. The suppressed TSH at this point was attributed to chronic narcotic use but FT4 and total T4 improved appropriately.

Conclusion:

There is no gold standard protocol for levothyroxine absorption test so we used a different protocol for LT4 dosing compared to the conventional regimen (1000 mcg of LT4). Our patient did show appropriate levothyroxine absorption on the calculated dose. Hence, the Levothyroxine absorption test may be used both as a diagnostic as well as a therapeutic tool for the patients with LT4 malabsorption causing PH.

References:

G.E. Sun, K.M. Pantalone, C. Faiman, M. Gupta, L. Olansky, B. Hatipoglu, The clinical utility of free thyroxine in oral levothyroxine absorption testing. Endocr. Pract. 20(9), 925–929 (2014)

Intrahepatic splenosis demonstrated by diffusion weighted MRI with histologic confirmation

Acquired ectopic splenic tissue is called splenosis, which is common after the history of trauma or surgical exploration. We present a rare case of intrahepatic splenosis in 36-year-old male patient mimicking a liver neoplasm on imaging however presented with left flank pain for 5 months and had remote history of splenectomy after splenic rupture from trauma. We discuss various imaging modalities and the role of various magnetic resonance imaging sequences and nuclear medicine examination. We also discuss the differentiating features to be kept to make the correct diagnosis along with a brief review of literature. We mentioned signal intensities of splenic lesions and normal signal intensity of spleen in different magnetic resonance imaging sequences and with high suspicion how we can diagnose splenosis and avoid unnecessary biopsy and its result related stress.

Noise Exposure on the London Underground, an Observational Study over a Decade

OBJECTIVES

There are no hearing protection regulations in place for passengers using public transport, such as the London Underground. In light of this, we sought to examine sound pressure levels experienced by regular users of the London Underground.

METHODS

Sound pressure levels (A-weighted decibels: dBA) were taken on moving London Underground carriages between Euston and South Wimbledon on the Northern Line, and between Euston and Vauxhall on the Victoria Line, during 2006 and 2018. In addition, carriage sound pressure levels travelling within Zone 1 of the London Underground were tested in 2019. Three experimental and three technical repeats were undertaken using a hand-held calibrated multi-function sound level meter.

RESULTS

Passengers are routinely and consistently subjected to sound pressure levels exceeding 80 dBA, with levels sometimes reaching over 100 dBA.

CONCLUSION

This study is unique within the literature, with no published studies outlining exposure levels for London Underground passengers. It provides evidence of elevated noise exposure to passengers, consistently along large stretches of the London Underground, over a prolonged study period (2006-2019).

KEY WORDS

Sensorineural hearing losssound pressureexposureLondonundergroundtube.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2020.

Acceptability and feasibility of mini-clinical evaluation exercise as a formative assessment tool for workplace-based assessment for surgical postgraduate students

Background:

Despite an increasing emphasis on workplace-based assessment (WPBA) during medical training, the existing assessment system largely relies on summative assessment while formative assessment is less valued. Various tools have been described for WPBA, mini-clinical evaluation exercise (mini-CEX) being one of them. Mini-CEX is well accepted in Western countries, however, reports of its use in India are scarce. We conducted this study to assess acceptability and feasibility of mini-CEX as a formative assessment tool for WPBA of surgical postgraduate students in an Indian setting.

Methods:

Faculty members and 2^nd year surgical residents were sensitized toward mini-CEX and requisite numbers of exercises were conducted. The difficulties during conduction of these exercises were identified, recorded, and appropriate measures were taken to address them. At the conclusion, the opinion of residents and faculty members regarding their experience with mini-CEX was taken using a questionnaire. The results were analyzed using simple statistical tools.

Results:

Nine faculty members out of 11 approached participated in the study (81.8%). All 16 2^nd year postgraduate surgical residents participated (100%). Sixty mini-CEX were conducted over 7 months. Each resident underwent 3–5 encounters. The mean time taken by the assessor for observation was 12.3 min (8–30 min) while the mean feedback time was 4.2 min (3–10 min). The faculty reported good overall satisfaction with mini-CEX and found it acceptable as a formative assessment tool. Three faculty members (33.3%) reported mini-CEX as more time-consuming while 2 (22.2%) found it difficult to carry the exercises often. All residents accepted mini-CEX and most of them reported good to high satisfaction with the exercises conducted.

Conclusions:

Mini-CEX is well accepted by residents and faculty as a formative assessment tool. It is feasible to utilize mini-CEX for WPBA of postgraduate students of surgery.

Usability of donor corneas harvested from the deceased having septicaemia or malignancy

CONTEXT

There is a wide gap between supply and demand in relation to healthy corneal grafts. Specific contraindications like infection and malignancy lead to non-usage of many grafts, despite the fact that deeming graft unhealthyness for these two contraindications is debatable.

AIMS

This study was conceptualized to assess if corneas donated from the deceased with septicaemia or malignancy can be deemed fit for implantation.

SETTINGS AND DESIGN

Retrospective histopathological and microbiological analysis of cadaveric donor corneas.

METHODS

A total of 76 donor corneas from 38 patients rejected for corneal transplantation in view of patient having septicaemia or malignancy were analysed for pathological and microbiological workup, to look for dissemination of disease within corneal tissue. Pathology workup included gross and microscopic histopathological evaluation of tissue. Microbiology workup included Grams stain and KOH with calcofluor mount, culture in blood agar, chocolate agar, Sabourauds dextrose agar and Mc Conkeys broth.

RESULTS

A total of 46 donor corneas of 23 septicaemia patients when evaluated showed presence of culture positive infection in 18 patients (78.2%). Histopathological examination done for 30 donor corneas from 15 cancer patients did not reveal presence of tumour cells in the specimen. Corneas of two of cancer patients having septicaemia revealed growth on cultures.

CONCLUSIONS

Corneal tissues harvested from septicaemia donors showed significantly higher incidence of corneal contamination, confirming their unsuitability for usage. However, there was no incidence of tumour transmission in corneal tissues of the patients with malignancies, suggesting that they can be considered for ophthalmic purpose.

Dispersion and topological characteristics of permutative polyatomic phononic crystals

This work presents a comprehensive mathematical treatment of phononic crystals (PCs) which comprise a finite lattice of repeated polyatomic unit cells. Wave dispersion in polyatomic lattices is susceptible to changes in the local arrangement of the monatoms (subcells) constituting the individual unit cell. We derive and interpret conditions leading to identical and contrasting band structures as well as the possibility of distinct eigenmodes as a result of cyclic and non-cyclic cellular permutations. Different modes associated with cyclic permutations yield topological invariance, which is assessed via the winding number of the complex eigenmode. Wave topology variations in the polyatomic PCs are quantified and conditions required to support edge modes in such lattices are established. Next, a transfer function analysis of finite polyatomic PCs is used to explain the formation of multiple Bragg band gaps as well as the emergence of truncation resonances within them. Anomalies arising from the truncation of the infinite lattice are further exploited to design mirror symmetrical edge modes in an extended lattice. We conclude with a generalized explanation of the band gap evolution mechanism based on the Bode plot analysis.

Updates in Treatment of Recurrent Clostridium difficile Infection

Recurrent Clostridium difficile infection (CDI) is a perpetual problem that leads to increased economic burden, higher healthcare cost, and significant morbidity and mortality. Its treatment remains a challenge. While various treatment approaches have been attempted with different levels of success, robust data establishing the superiority of one approach over the others is lacking. In this article, we review the current evidence pertaining to conventional pharmacological treatment as well as fecal microbiota transplantation (FMT) as a novel, rapidly emerging treatment modality for recurrent CDI.