Multicentre validation of point-of-care screening tool for heart failure: single-lead ECG recorded by smart stethoscope predicts low ejection fraction using artificial intelligence

Background/Introduction

Artificial intelligence (AI) applied to 12-lead ECG can identify left ventricular ejection fraction (EF) ≤35% with a sensitivity and specificity of 86.3% and 85.7%, respectively. Whether AI algorithms trained on 12-lead can accurately predict EF from single-lead ECGs (recorded by a smart stethoscope) remains unknown. This could facilitate point-of-care screening for low EF during routine clinical examination.

Purpose

First independent multicentre real-world UK National Health Service (NHS) prospective validation of 12-lead-ECG-trained AI algorithm applied to single-lead ECG recorded by a smart stethoscope, with AI algorithm tuned to detect EF ≤40%.

Methods

Prospective recruitment of unselected patients attending for echocardiography across six urban NHS hospital sites (UK). In addition to transthoracic echocardiogram (routine care), all participants had 15 seconds of supine, single-lead ECG recorded at six different positions (figure), encompassing standard anatomical positions for cardiac auscultation. A convolutional neural network (CNN) previously trained on 35,970 independent pairings of 12-lead-ECG and echocardiograms was retrained to use the single-lead ECG as input. Accuracy of CNN detection of low EF (binary ≤40%) is reported at a threshold of 0.5 against gold-standard; echo-determined percentage EF.

Results

Among 353 patients recruited (mean age 63±17; 58% male, 43.1% non-white), 309 (87.5%) had an EF >40%, and 44 (12.5%) had EF ≤40%. The best single recording position in isolation was position 3 (sensitivity 57.9% [42.2–73.6], specificity 86.3% [82.2–90.3]). Taking any of the six positions performed during the examination as predicting EF ≤40%, this achieved a sensitivity of 81.2% and specificity of 61.5%.

Conclusion(s)

In this first prospective multicentre validation study the retrained AI algorithm reliably detected low EF from single-lead ECGs acquired using a novel ECG-enabled stethoscope in standard auscultation positions. The ability to identify patients with possible low EF during routine physical examination addresses a significant unmet clinical need in point-of-care ruling in/out of heart failure, and has potential to provide broader population-level screening for asymptomatic cardiovascular disease.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute of Health Research, Accelerated Access Collaborative & NHSX: Artificial Intelligence in Health & Social Care Award

InGaN light-emitting diode stripes with reduced luminous exitance

InGaN light-emitting diodes of stripe geometries have been demonstrated. The elongated geometry facilitates light spreading in the longitudinal direction. The chips are further shaped by laser-micromachining to have partially-inclined sidewalls. The light extraction efficiencies of such 3D chip geometries are enhanced by ~12% (~8% according to ray-trace simulations), leading to a reduction of junction temperatures. The effective emission area is also increased four times compared to a cubic chip. The stripe LEDs are thus more efficient emitters with reduced luminous exitance, making them more suitable for a wide range of lighting applications.

Gentamicin-loaded strontium-containing hydroxyapatite bioactive bone cement--an efficient bioactive antibiotic drug delivery system

Modified strontium-containing hydroxyapatite (Sr-HA) bone cement was loaded with gentamicin sulfate to generate an efficient bioactive antibiotic drug delivery system for treatment of bone defects. Gentamicin release and its antibacterial property were determined by fluorometric method and inhibition of Staphylococcus aureus (S. aureus) growth. Gentamicin was released from Sr-HA bone cement during the entire period of study and reached around 38% (w/w) cumulatively after 30 days. Antibacterial activity of the gentamicin loaded in the cements is clearly confirmed by the growth inhibition of S. aureus. The results of the amount and duration of gentamicin release suggest a better drug delivery efficiency in Sr-HA bone cement over polymethylmethacrylate bone cement. Bioactivity of the gentamicin-loaded Sr-HA bone cement was confirmed with the formation of apatite layer with 1.836 ± 0.037 μm thick on day 1 and 5.177 ± 1.355 μm thick on day 7 after immersion in simulated body fluid. Compressive strengths of the gentamicin-loaded Sr-HA cement reached 132.60 ± 10.08 MPa, with a slight decrease from the unloaded groups by 4-9%. Bending moduli of Sr-HA cements with and without gentamicin were 1.782 ± 0.072 GPa and 1.681 ± 0.208 GPa, respectively. On the contrary, unloaded Sr-HA cement obtained slightly larger bending strength of 35.48 ± 2.63 MPa comparing with 33.00 ± 1.65 MPa for loaded cement. No statistical difference was found on the bending strengths and modulus of gentamicin-loaded and -unloaded Sr-HA cements. Sr-HA bone cement loaded with gentamicin was proven to be an efficient drug delivery system with uncompromised mechanical properties and bioactivity.

Phaeochromocytoma in the Hong Kong Chinese population

OBJECTIVE

To review the clinical manifestations of phaeochromocytoma in a Hong Kong Chinese population.

DESIGN

Retrospective review. SETTING. Five public hospitals in Hong Kong.

PATIENTS

Seventeen patients with operated phaeochromocytoma between 1994 and 2003 were reviewed retrospectively.

RESULTS

Six patients (35%) were men, 11 (65%) were women. The mean age at presentation was 47 (range, 17-72) years. The diagnosis post-presentation was delayed by 1 to 132 months. Over 70% of the patients had hypertension. The most frequent symptoms were headache (53%), palpitations (53%), and sweating (41%); all these symptoms were present in 24% of the patients. Four (24%) had hereditary phaeochromocytoma/paraganglioma syndrome. The sensitivity of 24-hour urinary catecholamine measurements was 82%. Mean urinary adrenaline and noradrenaline concentrations were respectively 7- and 8-fold greater than the upper reference limits. Computed tomography and metaiodobenzylguanidine scintigraphy were the most widely used means for tumour localisation (sensitivity, 100% and 87% respectively). Approximately 65% of the patients had intra-adrenal tumours; 53% were on right side, 18% were bilateral. All the patients were prescribed phenoxybenzamine (dosage range, 20-120 mg/day) preoperatively. Two thirds of the patients had improved blood pressure 1 year after the operation. No malignancy was reported after a mean follow-up period of 7 years.

CONCLUSION

Our series of patients with phaeochromocytomas commonly had a high frequency of normotension and extra-adrenal tumours. A high index of clinical suspicion and appropriate biochemical investigations are necessary to make the diagnosis, especially for patients manifesting adrenal incidentaloma and extra-adrenal lesion.

Apolipoprotein E ?4 allele is associated with the volume of white matter changes in patients with lacunar infarcts

The relationship between the apolipoprotein E (APOE) exon 4 polymorphism and white matter changes (WMC) in elderly subjects or patients with Alzheimer's disease is controversial. To investigate this polymorphism in relation to WMC in patients with lacunar infarcts, we prospectively observed 67 patients with acute lacunar infarct and 134 age- and sex-matched controls. Genotypes were determined using a nested polymerase chain reaction. WMC were measured quantitatively and were divided into two groups, severe and mild, with the mean volume of WMC as the cut point. Twenty-two patients (33%) had severe WMC. There was a significant difference in the distribution of APOE epsilon2, epsilon3, and epsilon4 alleles between severe and mild WMC groups (P = 0.002). The frequency of epsilon4 alleles was higher in patients with severe WMC than in those with mild WMC (25% vs. 7%, P = 0.003). These results suggest that APOE epsilon4 may exacerbate WMC in patients with lacunar infarcts. Further studies are required to confirm this finding.

Differential responses of temporal and nasal retinal neurites to regional-specific cues in the mouse retinofugal pathway

Retinal explants of mouse embryos were cultured together with explants of different regions in the retinofugal pathway in order to investigate whether ventral temporal (VT) and dorsal nasal (DN) retinal neurites showed differential responses to regional-specific cues in the pathway. In the presence of the chiasm, biased outgrowth of retinal neurites was found in explants of both retinal regions, which was accompanied by a reduction in total neurite growth in the VT but not the DN retina. Such differential responses to the diffusible negative influence were also observed when explants of two retinal origins were cocultured with the ventral diencephalon, but were not found with the dorsal diencephalon that contains targets of the optic axons. Indeed, extensive neurite invasion was found in the dorsal diencephalic explants and this ingrowth was more prominent for VT than DN neurites, showing a difference in axons from a distinct position in the retina to contact-mediated stimulatory activity within the target nuclei. We conclude that neurites from different regions of the retina show differential responses to the regional-specific cues in the diencephalon. These cues exist in both diffusible and contact-mediated forms that may shape the characteristic course and organization of retinal axons in decision regions of the optic pathway and the visual targets.

Acoustic flowmeter for the measurement of the mean flow velocity in pipes

This paper proposes a new technique for measuring the gas flow velocity averaged along the finite length of a pipe as well as over its cross-sectional area. Unlike the conventional gas flowmeters, the proposed technique exploits the one-dimensional plane waves that propagate uniformly across the pipe cross-sectional area. When a fluid flows along the pipe, the plane waves are superposed with the flow field such that the positive-going and negative-going plane wave components undergo the change of their wave numbers. Such wave number variation due to the mean flow velocity has provided a major motivation for developing a new way of measuring the mean flow velocity in the pipe, which is referred to as the acoustic flowmeter. To examine the feasibility of the developed flow velocity measurement method, including its theoretical backgrounds, experimental setups are illustrated in this paper. Detailed experimental data for the flow velocity range of 2-27 m/s reveal the linearity of the proposed acoustic flowmeter and its salient environmental robustness for the different acoustic pressure patterns in the pipe and, furthermore, for different velocity profiles over the pipe cross-section area.

Nitric oxide (NO.) stabilizes whereas nitrosonium (NO+) enhances filopodial outgrowth by rat retinal ganglion cells in vitro

Recent observations suggest that nitric oxide (NO(.)) can increase or decrease growth cone motility. Here, these apparently paradoxical results are explained by distinct actions of different NO-related species. Filopodial morphology of 223 rat retinal ganglion cells was monitored under computer-enhanced video microscopy in the presence of NO synthase (NOS) substrates or inhibitors, donors of specific NO-related species, and membrane-permeant cyclic nucleotide analogs. Physiological NOS activity induced filopodial outgrowth, whereas inhibition of NOS stabilized filopodia. Similar to NOS, nitrosonium (NO(+) transfer) and peroxynitrite (ONOO(-)), which can regulate the activity of growth-associated proteins by S-nitrosylation and oxidation, respectively, induced filopodial outgrowth. In contrast, NO(.), which stimulates guanylate cyclase to increase cGMP, stabilized filopodial activity. Thus disparate NO-related species may offer a dynamic process of filopodial growth regulation.

Vasopressin-induced calcium signaling in cultured hippocampal neurons

We recently demonstrated that the neural peptide vasopressin (AVP) can act as a neurotrophic factor for hippocampal nerve cells in culture. Because the neurotrophic effect of vasopressin is mediated by the V1 receptor [11], we investigated AVP activation of calcium signaling pathways in cultured hippocampal neurons. Results of this investigation demonstrate that exposure of cultured hippocampal neurons prelabeled with [3H]myo-inositol to vasopressin induced a significant accumulation of [3H]inositol-1-phosphate ([3H]IP1). The selective V1 vasopressin receptor agonist, [Phe2, Orn2]vasotocin, induced a significant accumulation of [3H]IP1 whereas a selective V2 vasopressin receptor agonist, [deamino1, D-Arg8]-vasopressin, did not. Moreover, V1 agonist-induced accumulation of [3H]IP1 was blocked by the selective V1 vasopressin receptor antagonist d(CH2)5[Tyr(Me)2]-vasopressin. V1 agonist-induced accumulation of [3H]IP1 was concentration dependent and exhibited a steep inverted U-shaped curve that included both stimulation and inhibition of [3H]IP1 accumulation. Time course analysis of V1 agonist-induced accumulation of [3H]IP1 revealed significant increase by 20 min which continued to be significantly elevated for 60 min. Investigation of the effect of closely related peptides on [3H]IP1 accumulation indicated that the vasopressin metabolite peptide AVP4-9 and oxytocin significantly increased [3H]IP1 accumulation whereas the vasopressin metabolite peptide AVP4-8 did not. AVP4-9 and oxytocin induced [3H]IP1 accumulation were blocked by the V1 vasopressin receptor antagonist d(CH2)5[Tyr(Me)2]-vasopressin. V1 receptor activation was associated with a pronounced rise in intracellular calcium. Results of calcium fluorometry studies indicated that V1 agonist exposure induced a marked and sustained rise in intracellular calcium that exhibited oscillations.(ABSTRACT TRUNCATED AT 250 WORDS)

Neutropenia in childhood with oral manifestation--a case report

Neutropenia is an unusual condition of blood dyscrasia in which the count of circulating neutrophils falls below the normal level. Neutrophil plays an important role in the host defense mechanism. The common clinical manifestations of neutropenia include ulcerative and inflammatory lesions in the oral cavity. A case of neutropenia of a seven-year-old girl is reported.

Vasopressin-induced calcium signaling in cultured hippocampal neurons

We recently demonstrated that the neural peptide vasopressin (AVP) can act as a neurotrophic factor for hippocampal nerve cells in culture. Because the neurotrophic effect of vasopressin is mediated by the V1 receptor, we investigated AVP activation of calcium signaling pathways in cultured hippocampal neurons. Results of this investigation demonstrate that exposure of cultured hippocampal neurons prelabeled with [3H]myo-inositol to vasopressin induced a significant accumulation of [3H]inositol-1-phosphate ([3H]IP1). The selective V1 vasopressin receptor agonist, [Phe2, Orn2]vasotocin, induced a significant accumulation of [3H]IP1 whereas a selective V2 vasopressin receptor agonist, [deamino1, D-Arg8]-vasopressin, did not. Moreover, V1 agonist-induced accumulation of [3H]IP1 was blocked by the selective V1 vasopressin receptor antagonist d(CH2)5[Tyr(Me)2]-vasopressin. V1 agonist-induced accumulation of [3H]IP1 was concentration dependent and exhibited a steep inverted U-shaped curve that included both stimulation and inhibition of [3H]IP1 accumulation. Time course analysis of V1 agonist-induced accumulation of [3H]IP1 revealed significant increase by 20 min which continued to be significantly elevated for 60 min. Investigation of the effect of closely related peptides on [3H]IP1 accumulation indicated that the vasopressin metabolite peptide AVP4-9 and oxytocin significantly increased [3H]IP1 accumulation whereas the vasopressin metabolite peptide AVP4-8 did not. AVP4-9 and oxytocin induced [3H]IP1 accumulation were blocked by the V1 vasopressin receptor antagonist d(CH2)5[Tyr(Me)2]-vasopressin. V1 receptor activation was associated with a pronounced rise in intracellular calcium. Results of calcium fluorometry studies indicated that V1 agonist exposure induced a marked and sustained rise in intracellular calcium that exhibited oscillations.(ABSTRACT TRUNCATED AT 250 WORDS)

Rubinstein-Taybi syndrome

A case of Rubinstein-Taybi syndrome (RTS) is presented. The syndrome is characterized by broad thumbs and great toes, peculiar facial features and mental retardation. The oral findings of the patient are reported, and the dental management is discussed.

Bilateral malposition of maxillary second premolars: report of case

A case of bilateral malposition of maxillary second premolars is reported. Different approaches for management are considered. The possible causes of the rare abnormality are discussed.

Custom-made veneers for permanent anterior teeth

The reduction of the enamel on the labial surface of the affected teeth makes the procedure irreversible. However, the procedures provide a superior functional and, more importantly, physiological result while still offering a conservative type of treatment. The uniqueness of the technique is in its ability to restore the physiological relationship of the gingiva and the labial surface, rather than to compromise this relationship by making a bulbous tooth of a greater labiolingual dimension than a normal tooth. It must be explained to the patients who require this type of procedure that the next step would be the complete reduction of the affected teeth and the construction of porcelain jacket crowns.