Oxidation of Protein Kinase A Regulatory Subunit PKARIα Protects Against Myocardial Ischemia-Reperfusion Injury by Inhibiting Lysosomal-Triggered Calcium Release.

BACKGROUND: Kinase oxidation is a critical signaling mechanism through which changes in the intracellular redox state alter cardiac function. In the myocardium, PKARIα (type-1 protein kinase A) can be reversibly oxidized, forming interprotein disulfide bonds in the holoenzyme complex. However, the effect of PKARIα disulfide formation on downstream signaling in the heart, particularly under states of oxidative stress such as ischemia and reperfusion (I/R), remains unexplored. METHODS: Atrial tissue obtained from patients before and after cardiopulmonary bypass and reperfusion and left ventricular (LV) tissue from mice subjected to I/R or sham surgery were used to assess PKARIα disulfide formation by immunoblot. To determine the effect of disulfide formation on PKARIα catalytic activity and subcellular localization, live-cell fluorescence imaging and stimulated emission depletion super-resolution microscopy were performed in prkar1 knock-out mouse embryonic fibroblasts, neonatal myocytes, or adult LV myocytes isolated from "redox dead" (Cys17Ser) PKARIα knock-in mice and their wild-type littermates. Comparison of intracellular calcium dynamics between genotypes was assessed in fura2-loaded LV myocytes, whereas I/R-injury was assessed ex vivo. RESULTS: In both humans and mice, myocardial PKARIα disulfide formation was found to be significantly increased (2-fold in humans, P=0.023; 2.4-fold in mice, P<0.001) in response to I/R in vivo. In mouse LV cardiomyocytes, disulfide-containing PKARIα was not found to impact catalytic activity, but instead led to enhanced AKAP (A-kinase anchoring protein) binding with preferential localization of the holoenzyme to the lysosome. Redox-dependent regulation of lysosomal two-pore channels by PKARIα was sufficient to prevent global calcium release from the sarcoplasmic reticulum in LV myocytes, without affecting intrinsic ryanodine receptor leak or phosphorylation. Absence of I/R-induced PKARIα disulfide formation in "redox dead" knock-in mouse hearts resulted in larger infarcts (2-fold, P<0.001) and a concomitant reduction in LV contractile recovery (1.6-fold, P<0.001), which was prevented by administering the lysosomal two-pore channel inhibitor Ned-19 at the time of reperfusion. CONCLUSIONS: Disulfide modification targets PKARIα to the lysosome, where it acts as a gatekeeper for two-pore channel-mediated triggering of global calcium release. In the postischemic heart, this regulatory mechanism is critical for protection from extensive injury and offers a novel target for the design of cardioprotective therapeutics.

Assessment of the causal relevance of ECG parameters for risk of atrial fibrillation: A mendelian randomisation study.

BACKGROUND: Atrial electrical and structural remodelling in older individuals with cardiovascular risk factors has been associated with changes in surface electrocardiographic (ECG) parameters (e.g., prolongation of the PR interval) and higher risks of atrial fibrillation (AF). However, it has been difficult to establish whether altered ECG parameters are the cause or a consequence of the myocardial substrate leading to AF. This study aimed to examine the potential causal relevance of ECG parameters on risk of AF using mendelian randomisation (MR). METHODS AND FINDINGS: Weighted genetic scores explaining lifelong differences in P-wave duration, PR interval, and QT interval were constructed, and associations between these ECG scores and risk of AF were estimated among 278,792 UK Biobank participants (mean age: 57 years at recruitment; 19,132 AF cases). The independent genetic variants contributing to each of the separate ECG scores, and their corresponding weights, were based on published genome-wide association studies. In UK Biobank, genetic scores representing a 5 ms longer P-wave duration or PR interval were significantly associated with lower risks of AF (odds ratio [OR] 0.91; 95% confidence interval [CI]: 0.87-0.96, P = 2 × 10-4 and OR 0.94; 95% CI: 0.93-0.96, P = 2 × 10-19, respectively), while longer QT interval was not significantly associated with AF. These effects were independently replicated among a further 17,931 AF cases from the AFGen Consortium. Investigation of potential mechanistic pathways showed that differences in ECG parameters associated with specific ion channel genes had effects on risk of AF consistent with the overall scores, while the overall scores were not associated with changes in left atrial size. Limitations of the study included the inherent assumptions of MR, restriction to individuals of European ancestry, and possible restriction of results to the normal ECG ranges represented in UK Biobank. CONCLUSIONS: In UK Biobank, we observed evidence suggesting a causal relationship between lifelong differences in ECG parameters (particularly PR interval) that reflect longer atrial conduction times and a lower risk of AF. These findings, which appear to be independent of atrial size and concomitant cardiovascular comorbidity, support the relevance of varying mechanisms underpinning AF and indicate that more individualised treatment strategies warrant consideration.

First clinical use of novel ablation catheter incorporating local impedance data.

INTRODUCTION: Successful catheter ablation is limited by both poor spatial resolution of abnormal local signals and inability to deliver an effective lesion due to poor tissue contact. We report first worldwide use of the Intellanav MiFi OI catheter (Boston Scientific), providing ultra-high density mapping and incorporating a "DirectSense" algorithm to measure local tissue impedance (LI). METHODS AND RESULTS: 31 patients (65±6 years, 20 male) underwent ablation. LI from the catheter, generator impedance (GI) and maximum electrogram amplitude were recorded in the blood pool, and in regions from healthy to dense scar before, during and after ablation. The catheter demonstrated clear nearfield signal where standard bipolar recordings included farfield signal. LI was lower in dense scar than either healthy tissue or blood pool, and demonstrated an exponential relationship with maximum electrogram amplitude. Maximum LI drop on ablation linearly correlated with initial LI. The median LI drop for successful lesions, resulting in lack of local tissue capture, was 16.0Ω (12.1-19.8 Ω) for LV and 14.6 Ω (10.0-18.3 Ω) for LA, which was larger than for unsuccessful lesions (LV: 9.4 Ω [5.4-15.6 Ω] P = 0.001; LA: 6.8 Ω [4.7-13.0 Ω], P = 0.049). LI percentage drop was also significantly larger for successful than unsuccessful lesions (LV: 17.1 Ω [14.0-19.6 Ω] vs. 10.6 Ω (7.1-16.5 Ω) P = 0.002; LA: 14.2 Ω [10.8-19.5 Ω] vs. 7.5Ω [5.1-11.0 Ω], P = 0.005). CONCLUSION: This novel catheter gives reproducible recordings of local impedance, which are dependent on scar level. Absolute LI drop, and also percentage drop, on ablation may give an indication of tissue contact and subsequent effective lesion formation.

Improved outcome and cost effectiveness in ablation of persistent atrial fibrillation under general anaesthetic.

Aims: Outcome of persistent atrial fibrillation (AF) ablation remains suboptimal. Techniques employed to reduce arrhythmia recurrence rate are more likely to be embraced if cost-effectiveness can be demonstrated. A single-centre observational study assessed whether use of general anaesthesia (GA) in persistent AF ablation improved outcome and was cost-effective. Methods and results: Two hundred and ninety two patients undergoing first ablation procedures for persistent AF under conscious sedation or GA were followed. End points were freedom from listing for repeat ablation at 18 months and freedom from recurrence of atrial arrhythmia at 1 year. Freedom from atrial arrhythmia was higher in patients who underwent ablation under GA rather than sedation (63.9% vs. 42.3%, hazard ratio (HR) 1.87, 95% confidence interval (CI): 1.23-2.86, P = 0.002). Significantly fewer GA patients were listed for repeat procedures (29.2% vs. 42.7%, HR 1.62, 95% CI: 1.01-2.60, P = 0.044). Despite GA procedures costing slightly more, a saving of £177 can be made per patient in our centre for a maximum of two procedures if all persistent AF ablations are performed under GA. Conclusions: In patients with persistent AF, it is both clinical and economically more effective to perform ablation under GA rather than sedation.

Coarse fibrillatory waves in atrial fibrillation predict success of electrical cardioversion.

BACKGROUND: To determine whether the presence of "coarse" fibrillatory waves (Fw) seen on surface ECGs of patients with persistent atrial fibrillation (AF) predict maintenance of sinus rhythm (SR) at 6 weeks after electrical cardioversion (ECV). METHODS: Preprocedure ECGs from 94 consecutive patients with persistent AF scheduled to undergo ECV at a single centre were classified as having coarse Fw (≥0.1 mV) or fine Fw (<0.1 mV) in leads II or V1 . The primary outcome was ECG rhythm at 6-week clinical follow-up. Demographic and echocardiographic data were also collected. RESULTS: Thirty-two patient ECGs (34%) had coarse Fw on baseline ECG in either or both leads II or V1 with no significant differences in baseline demographics compared to those patients with fine Fw. At 6 weeks post-ECV, in the coarse Fw group 72% of patients maintained SR vs. 42% in the fine Fw group (χ2 , p = .006) with the odds ratio (OR) of maintaining SR at 6 weeks in the presence of coarse Fw being 3.5 (95% CI: 1.4-8.9, p = .007). Across the overall study population, there were no other significant univariate predictors of SR at 6 weeks post-ECV. CONCLUSION: Classifying persistent AF using the maximal Fw amplitude on a surface ECG is a simple and reproducible method of predicting medium-term success of ECV, independent of traditional risk factors.

Applicability of a risk score for prediction of the long-term benefit of the implantable cardioverter defibrillator in patients receiving cardiac resynchronization therapy.

AIMS: The Goldenberg risk score, comprising five clinical risk factors (New York Heart Association class >2, atrial fibrillation, QRS duration >120 ms, age >70 years, and urea >26 mg/dL), may help identify patients in whom the survival benefit of the defibrillator may be limited. We aim at assessing whether this score can accurately predict the long-term all-cause mortality risk of patients receiving cardiac resynchronization therapy (CRT) and identify those who are more likely to benefit from the defibrillator. METHODS AND RESULTS: In this retrospective observational cohort study, 638 patients with ischaemic or non-ischaemic dilated cardiomyopathy who had CRT-defibrillator (CRT-D) (n = 224) vs. CRT-pacemaker (CRT-P) (n = 414) implantation were prospectively followed up for survival outcomes. The long-term outcome of patients with CRT-D vs. CRT-P was compared within risk score categories and in patients with severe renal dysfunction. Mean follow-up in surviving and deceased patients was 62.7 and 32.5 months, respectively. This score showed higher discriminative performance in all-cause mortality prediction in CRT-D vs. CRT-P patients (area under the curve 0.718 ± 0.041 vs. 0.650 ± 0.032, respectively, P = 0.001). In those with scores 0-2, a CRT-D device decreased mortality rates in the first 4 years of follow-up compared with CRT-P (11.3 vs. 24.7%, P = 0.041), but this effect attenuated with longer follow-up duration (21.2 vs. 32.7%, P = 0.078). In this group, the benefit of CRT-D during the follow-up was seen after adjusting for traditional mortality predictors (hazard ratio 0.339, P = 0.001). No significant differences in mortality rates were seen in patients with score ≥3 (57.9% with CRT-D vs. 56.9%, P = 0.8) and those with severe renal dysfunction (92.9% in CRT-D vs. 76.2%, P = 0.17). Similar results were seen following propensity score matching. CONCLUSION: A simple risk stratification score comprising five clinical risk factors may help identify CRT patients who are more likely to benefit from the presence of the defibrillator.

Independent effects of adiposity measures on risk of atrial fibrillation in men and women: a study of 0.5 million individuals.

BACKGROUND: Atrial fibrillation (AF) has a higher prevalence in men than in women and is associated with measures of adiposity and lean mass (LM). However, it remains uncertain whether the risks of AF associated with these measures vary by sex. METHODS: Among 477 904 UK Biobank participants aged 40-69 without prior AF, 23 134 incident AF cases were identified (14 400 men, 8734 women; median follow-up 11.1 years). Cox proportional hazards models were used to estimate the covariate adjusted hazard ratios (HRs) describing the association of AF with weight, measures of adiposity [fat mass (FM), waist circumference (WC)] and LM, and their independent relevance, by sex. RESULTS: Weight and WC were independently associated with risk of AF [HR: 1.25 (1.23-1.27) per 10 kg, HR: 1.11 (1.09-1.14) per 10 cm, respectively], with comparable effects in both sexes. The association with weight was principally driven by LM, which, per 5 kg, conferred double the risk of AF compared with FM when mutually adjusted [HR: 1.20 (1.19-1.21), HR: 1.10 (1.09-1.11), respectively]; however, the effect of LM was weaker in men than in women (p-interaction = 4.3 x 10-9). Comparing the relative effects of LM, FM and WC identified different patterns within each sex; LM was the strongest predictor for both, whereas WC was stronger than FM in men but not in women. CONCLUSIONS: LM and FM (as constituents of weight) and WC are risk factors for AF. However, the independent relevance of general adiposity for AF was more limited in men than in women. The relevance of both WC and LM suggests a potentially important role for visceral adiposity and muscle mass in AF development.

Mechanisms Underlying Vascular Endothelial Growth Factor Receptor Inhibition-Induced Hypertension: The HYPAZ Trial.

[Figure: see text].

Admission of patients with STEMI since the outbreak of the COVID-19 pandemic: a survey by the European Society of Cardiology.

AIMS: The COVID-19 pandemic required a significant redeployment of worldwide healthcare resources. Fear of infection, national lockdowns and altered healthcare priorities have the potential to impact utilisation of healthcare resources for non-communicable diseases. To survey health professionals' views of the impact of the COVID-19 pandemic on the rate and timing of admission of patients with ST-elevation myocardial infarction (STEMI), the European Society of Cardiology (ESC) administered an internet-based questionnaire to cardiologists and cardiovascular nurses across 6 continents. METHODS AND RESULTS: 3101 responses were received from 141 countries across 6 continents. 88.3% responded that their country was in "total lockdown" and 7.1% in partial lockdown. 78.8% responded that the number of patients presenting with STEMI was reduced since the coronavirus outbreak and 65.2% indicated that the reduction in STEMI presentations was >40%. Approximately 60% of all respondents reported that STEMI patients presented later than usual and 58.5% that >40% of STEMI patients admitted to hospital presented beyond the optimal window for primary percutaneous intervention (PCI) or thrombolysis. Independent predictors of the reported higher rate of delayed STEMI presentation were a country in total lockdown, >100 COVID-19 cases admitted locally, and the complete restructuring of the local cardiology service. CONCLUSION: The survey indicates that the impact of COVID-19 on STEMI presentations is likely to be substantial, with both lower presentations and a higher rate of delayed presentations occurring. This has potentially important ramifications for future healthcare and policy planning in the event of further waves of this pandemic.

Use of Novel Electrogram "Lumipoint" Algorithm to Detect Critical Isthmus and Abnormal Potentials for Ablation in Ventricular Tachycardia.

OBJECTIVES: This study reports the use of a novel "Lumipoint" algorithm in ventricular tachycardia (VT) ablation. BACKGROUND: Automatic mapping systems aid rapid acquisition of activation maps. However, they may annotate farfield rather than nearfield signal in low voltage areas, making maps difficult to interpret. The Lumipoint algorithm analyzes the complete electrogram tracing and therefore includes nearfield signals in its analysis. METHODS: Twenty-two patients with ischemic cardiomyopathy and 5 with dilated cardiomyopathy underwent mapping using the ultra-high density Rhythmia system. Lumipoint algorithms were applied retrospectively. RESULTS: In all left ventricular substrate maps, changing the window of interest to the post-QRS phase automatically identified late potentials. In 25 of 27 left ventricular VT activation maps, a minimum spatial window of interest correctly identified the VT isthmus as seen by the manually annotated map, entrainment, and response to ablation. In 6 maps, the algorithm identified the isthmus where the standard automatically annotated map did not. CONCLUSIONS: The Lumipoint algorithm automatically highlights areas with electrograms having specific characteristics or timings. This can identify late and fractionated potentials and regions that exhibit discontinuous activation, as well as the isthmus of a VT circuit. These features may enhance human interpretation of the electrogram signals during a case, particularly where the circuit lies in partial scar with low amplitude nearfield signals and potentially allow a more targeted ablation strategy.

Effect of Activation Wavefront on Electrogram Characteristics During Ventricular Tachycardia Ablation.

Background Catheter ablation of ventricular tachycardia (VT) in structural heart disease is challenging because of noninducibility or hemodynamic compromise. Ablation often depends on elimination of local abnormal ventricular activities (LAVAs) but which may be hidden in far-field signal. We investigated whether altering activation wavefront affects activation timing and LAVA characterization and allows a better understanding of isthmus anatomy. Methods Patients with ischemic cardiomyopathy underwent mapping using the ultra-high density Rhythmia system (Boston Scientific). Maps were generated for all stable VTs and with pacing from the atrium, right ventricular apex, and an left ventricular branch of the coronary sinus. Results Fifty-six paced maps and 23 VT circuits were mapped in 22 patients. In 79% of activation maps, there was ≥1 line of block in the paced conduction wavefront, with 93% having fixed block and 32% showing functional partial block. Bipolar scar was larger with atrial than right ventricular (31.7±18.5 versus 27.6±16.3 cm2, P=0.003) or left ventricular pacing (31.7±18.5 versus 27.0±19.2 cm2, P=0.009); LAVA areas were smaller with atrial than right ventricular (12.3±10.5 versus 18.4±11.0 cm2, P<0.001) or left ventricular pacing (12.3±10.5 versus 17.1±10.7 cm2, P<0.001). LAVA areas were larger with wavefront propagation perpendicular versus parallel to the line of block along isthmus boundaries (19.3±7.1 versus 13.6±7.4 cm2, P=0.01). All patients had successful VT isthmus ablation. In 11±8 months follow-up, 2 patients had a recurrence. Conclusions Wavefronts of conduction slowing/block may aid identification of critical isthmuses in unmappable VTs. Altering the activation wavefront leads to significant differences in conduction properties of myocardial tissue, along with scar and LAVA characterization. In patients where few LAVAs are identified during substrate mapping, using an alternate activation wavefront running perpendicular to the VT isthmus may increase sensitivity to detect arrhythmogenic substrate and critical sites for reentry.

Ultra-High-Density Activation Mapping to Aid Isthmus Identification of Atrial Tachycardias in Congenital Heart Disease.

OBJECTIVES: A new electroanatomic mapping system (Rhythmia, Boston Scientific, Marlborough, Massachusetts) using a 64-electrode mapping basket is now available; we systematically assessed its use in complex congenital heart disease (CHD). BACKGROUND: The incidence of atrial arrhythmias post-surgery for CHD is high. Catheter ablation has emerged as an effective treatment, but is hampered by limitations in the mapping system's ability to accurately define the tachycardia circuit. METHODS: Mapping and ablation data of 61 patients with CHD (35 males, age 45 ± 14 years) from 8 tertiary centers were reviewed. RESULTS: Causes were as follows: Transposition of Great Arteries (atrial switch) (n = 7); univentricular physiology (Fontans) (n = 8); Tetralogy of Fallot (n = 10); atrial septal defect (ASD) repair (n = 15); tricuspid valve (TV) anomalies (n = 10); and other (n = 11). The total number of atrial arrhythmias was 86. Circuits were predominantly around the tricuspid valve (n = 37), atriotomy scar (n = 10), or ASD patch (n = 4). Although the majority of peri-tricuspid circuits were cavo-tricuspid-isthmus dependent (n = 30), they could follow a complex route between the annulus and septal resection, ASD patch, coronary sinus, or atriotomy. Immediate ablation success was achieved in all but 2 cases; with follow-up of 12 ± 8 months, 7 patients had recurrence. CONCLUSIONS: We demonstrate the feasibility of the basket catheter for mapping complex CHD arrhythmias, including with transbaffle and transhepatic access. Although the circuits often involve predictable anatomic landmarks, the precise critical isthmus is often difficult to predict empirically. Ultra-high-density mapping enables elucidation of circuits in this complex anatomy and allows successful treatment at the isthmus with a minimal lesion set.

Should Technical and Anatomical Difficulties Discourage Operators From Embarking on Transradial Access for Percutaneous Coronary Intervention?

BACKGROUND: Use of the radial approach for PCI procedures is increasing due to lower rates of access-site complications/bleeding, and patient preference. However, femoral operators switching may be discouraged by the learning curve and by anatomical issues that may complicate the procedure. We aimed to define the frequency of anatomic variants and success rates during transradial access for PCI. METHODS: We retrospectively analyzed 2588 cases of PCI attempted by the radial route; radial/brachial and subclavian angiography was performed when obstructions were encountered. Presence of anatomical variants, spasm, and ability to complete the procedure were noted. RESULTS: Radial procedures were successfully completed in 2741/2588 cases (98.2%); in the remainder, switching to femoral approach was necessary. Local arteriography was performed in 221/2588 cases (8.5%) due to difficulties encountered; of these, 131/221 difficulties (59%) were due to problems at the radial arterial level, 58/221 (26%) were due to problems at the subclavian level, and 32/221 (15%) were due to problems at brachial arterial sites. Extreme radial tortuosity (18%) and radial loop (20%) had relatively lower rates of success followed by subclavian tortuosity (73%). Females had significantly higher incidences of radial spasm (6% vs 1.9% in men; P<.001), radial tortuosity (3.4% vs 1.7% in men; P=.01), and subclavian tortuosity (3.8% vs 1.8% in men; P<.01). CONCLUSION: Inability to successfully complete invasive procedures via the radial approach is uncommon. Even when encountered, most difficulties can be overcome with the use of vasodilators and hydrophilic wires. These data provide reassurance for would-be radial converts that the learning curve may not be as steep as envisaged.

Ablation of Complex Fractionated Electrograms Improves Outcome in Persistent Atrial Fibrillation of Over 2 Year's Duration.

AIM: There is controversy and sparse data on whether substrate based techniques in addition to pulmonary vein isolation (PVI) confer benefit in the catheter ablation of persistent atrial fibrillation (AF), especially if long standing. We performed an observational study to assess whether substrate based ablation improved freedom from atrial arrhythmia. METHODS: A total of 286 patients undergoing first ablation procedures for persistent AF with PVI only(n = 79), PVI plus linear ablation(n = 85), or PVI plus complex fractionated electrogram (CFAE) and linear ablation(n = 107) were followed. Primary end point was freedom from atrial arrhythmia at one year. RESULTS: Mean duration of pre-procedure time in AF was 28+/-27 months.There were no differences in baseline characteristics between groups except a higher proportion of patients with a severely dilated LA in those receiving PVI+CFAEs+lines. Freedom from atrial arrhythmia was higher with a PVI+CFAE+lines strategy then for PVI alone (HR 1.56, 95% CI: 1.04-2.34, p=0.032) but was not higher with PVI+lines. Benefit of substrate modification was conferred for preprocedure times in AF of over 30 months. The occurrence of atrial tachycardia was higher when lines were added to the ablation strategy (HR 0.08, 95% CI: 0.01-0.59, p=0.014). Freedom from atrial arrhythmia at 1 year was higher with lower patient age, use of general anaesthetic (GA), normal or mildly dilated left atrium and decreasing time in AF. CONCLUSIONS: In patients with long standing persistent AF of over 30 months duration,CFAE ablation resulted in improved freedom from atrial arrhythmia. Increased freedom from atrial arrhythmia occurs in patients who are younger and have smaller atria, and with GA procedures. Linear ablation did not improve outcome and resulted in a higher incidence of atrial tachycardia.

Palpitations in a 72-year-old woman.

CLINICAL INTRODUCTION: A 72-year-old woman presented with an 8-year history of palpitations occurring every few weeks. They were sudden in onset, were associated with dizziness and could last for up to 2 hours. She was prescribed bisoprolol which reduced the frequency of events but did not abolish them. Baseline ECG and echocardiography were normal. She was referred for electrophysiological study. Despite initial difficulties, diagnostic catheters were placed in the right ventricular (RV) apex and in the coronary sinus (CS) via the right internal jugular vein and superior vena cava (SVC) (figure 1A). A narrow complex tachycardia was easily induced, and ablation was then delivered during tachycardia with the ablation catheter positioned as shown in (figure 1A). This terminated tachycardia 4 s after onset of energy delivery and on follow-up she has remained asymptomatic. She later underwent a CT scan (figure 1B,C; online supplementary video).DC1SP110.1136/heartjnl-2017-311734.supp1Supplementary file 1 heartjnl;103/19/1554/F1F1F1Figure 1(A) Fluoroscopy of catheter placement. (B) Sagittal contrast-enhanced CT image. (C) Axial contrast-enhanced CT. QUESTION: What anatomical abnormality caused difficulty in catheter placement during the procedure?Azygous continuation of the inferior vena cava (IVC)Giant Eustachian valveDextrocardiaRenal tumour compressing IVC.

Flow rates through intravenous access devices: an in vitro study.

STUDY OBJECTIVE: Fluid administration using intravenous (IV) access devices is required in many settings. There are a lack of quantitative data comparing traditional cannulas and modern access devices. We aimed to investigate flow rates through modern intravenous access devices using an in vitro system. DESIGN: This is an experimental study. SETTING AND MEASUREMENTS: Rates of flow of intravenous fluids (crystalloid and colloid) were measured through various access devices using a uroflowmeter. Standardized conditions and repeat measurements ensured validity. Fluid was administered with or without the addition of a pressure bag and needle-free valve. MAIN RESULTS: Increasing the size of cannulas improved flow. Fourteen-gauge cannulas had significantly higher mean flow rates compared to 14G central venous lines in all conditions (136% higher with no pressure bag/valve; 95% CI, +130% to +152%; P < .001). Both the emergency infusion device and rapid infusion catheter produced significantly increased mean flows compared to a 14G cannula (12% higher for emergency infusion catheter; 95% CI, +7% to +15%; P = .008, and 15% higher for rapid infusion catheter; 95% CI, +12% to +21%; P = .004). The needle-free valve significantly impaired flow on 16G and wider IV access devices (36% lower with no pressure bag using 14G cannula; 95% CI, -29% to -46%; P = .003), but flow reductions in narrower IV access were insignificant. Pressure bags significantly improved flow in all devices, in all combinations. CONCLUSIONS: Flow rates in IV devices can be maximized by pressure bag use and removal of needle-free valves. The rapid infusion catheter and emergency infusion catheter allow some increase in flow over a 14G cannula. Familiarity with varying flow rates across IV access devices could better inform clinical decisions.

Wearable technology: using Google Glass as a teaching tool.

Wearable technology holds great promise in revolutionising healthcare delivery. The benefits can also be seen in medical education and delivering healthcare in remote places. We report the use of Google Glass technology as a teaching tool in broadcasting a procedure onto a mobile phone as a viewer, replacing expensive and often cumbersome existing equipment.