578 results found
Dhutia NM, Zolgharni M, Mielewczik M, et al., 2017, Open-source, vendor-independent, automated multi-beat tissue Doppler echocardiography analysis, International Journal of Cardiovascular Imaging, Vol: 33, Pages: 1135-1148, ISSN: 1569-5794
Current guidelines for measuring cardiac function by tissue Doppler recommend using multiple beats, but this has a time cost for human operators. We present an open-source, vendor-independent, drag-and-drop software capable of automating the measurement process. A database of ~8000 tissue Doppler beats (48 patients) from the septal and lateral annuli were analyzed by three expert echocardiographers. We developed an intensity- and gradient-based automated algorithm to measure tissue Doppler velocities. We tested its performance against manual measurements from the expert human operators. Our algorithm showed strong agreement with expert human operators. Performance was indistinguishable from a human operator: for algorithm, mean difference and SDD from the mean of human operators’ estimates 0.48 ± 1.12 cm/s (R2 = 0.82); for the humans individually this was 0.43 ± 1.11 cm/s (R2 = 0.84), −0.88 ± 1.12 cm/s (R2 = 0.84) and 0.41 ± 1.30 cm/s (R2 = 0.78). Agreement between operators and the automated algorithm was preserved when measuring at either the edge or middle of the trace. The algorithm was 10-fold quicker than manual measurements (p < 0.001). This open-source, vendor-independent, drag-and-drop software can make peak velocity measurements from pulsed wave tissue Doppler traces as accurately as human experts. This automation permits rapid, bias-resistant multi-beat analysis from spectral tissue Doppler images.
De Pooter J, El Haddad M, De Buyzere M, et al., 2017, Biventricular Paced QRS Area Predicts Acute Hemodynamic CRT Response Better Than QRS Duration or QRS Amplitudes, JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Vol: 28, Pages: 192-200, ISSN: 1045-3873
Sands SA, Mebrate Y, Edwards BA, et al., 2017, Resonance as the mechanism of daytime periodic breathing in patients with heart failure, American Journal of Respiratory and Critical Care Medicine, Vol: 195, Pages: 237-246, ISSN: 1073-449X
Rationale: In patients with chronic heart failure, daytime oscillatory breathing at rest is associated with a high risk of mortality. Experimental evidence, including exaggerated ventilatory responses to CO2 and prolonged circulation time, implicates the ventilatory control system and suggests feedback instability (loop gain > 1) is responsible. However, daytime oscillatory patterns often appear remarkably irregular versus classic instability (Cheyne-Stokes respiration), suggesting our mechanistic understanding is limited.Objectives: We propose that daytime ventilatory oscillations generally result from a chemoreflex resonance, in which spontaneous biological variations in ventilatory drive repeatedly induce temporary and irregular ringing effects. Importantly, the ease with which spontaneous biological variations induce irregular oscillations (resonance “strength”) rises profoundly as loop gain rises toward 1. We tested this hypothesis through a comparison of mathematical predictions against actual measurements in patients with heart failure and healthy control subjects.Methods: In 25 patients with chronic heart failure and 25 control subjects, we examined spontaneous oscillations in ventilation and separately quantified loop gain using dynamic inspired CO2 stimulation.Measurements and Main Results: Resonance was detected in 24 of 25 patients with heart failure and 18 of 25 control subjects. With increased loop gain—consequent to increased chemosensitivity and delay—the strength of spontaneous oscillations increased precipitously as predicted (r = 0.88), yielding larger (r = 0.78) and more regular (interpeak interval SD, r = −0.68) oscillations (P < 0.001 for all, both groups combined).Conclusions: Our study elucidates the mechanism underlying daytime ventilatory oscillations in heart failure and provides a means to measure and interpret these oscillations to r
Sands SA, Mebrate Y, Edwards BA, et al., 2017, Resonance as the Mechanism of Daytime Periodic Breathing in Patients with Heart Failure., Am J Respir Crit Care Med, Vol: 195, Pages: 237-246
RATIONALE: In patients with chronic heart failure, daytime oscillatory breathing at rest is associated with a high risk of mortality. Experimental evidence, including exaggerated ventilatory responses to CO2 and prolonged circulation time, implicates the ventilatory control system and suggests feedback instability (loop gain > 1) is responsible. However, daytime oscillatory patterns often appear remarkably irregular versus classic instability (Cheyne-Stokes respiration), suggesting our mechanistic understanding is limited. OBJECTIVES: We propose that daytime ventilatory oscillations generally result from a chemoreflex resonance, in which spontaneous biological variations in ventilatory drive repeatedly induce temporary and irregular ringing effects. Importantly, the ease with which spontaneous biological variations induce irregular oscillations (resonance "strength") rises profoundly as loop gain rises toward 1. We tested this hypothesis through a comparison of mathematical predictions against actual measurements in patients with heart failure and healthy control subjects. METHODS: In 25 patients with chronic heart failure and 25 control subjects, we examined spontaneous oscillations in ventilation and separately quantified loop gain using dynamic inspired CO2 stimulation. MEASUREMENTS AND MAIN RESULTS: Resonance was detected in 24 of 25 patients with heart failure and 18 of 25 control subjects. With increased loop gain-consequent to increased chemosensitivity and delay-the strength of spontaneous oscillations increased precipitously as predicted (r = 0.88), yielding larger (r = 0.78) and more regular (interpeak interval SD, r = -0.68) oscillations (P < 0.001 for all, both groups combined). CONCLUSIONS: Our study elucidates the mechanism underlying daytime ventilatory oscillations in heart failure and provides a means to measure and interpret these oscillations to reveal the underl
Captur G, Karperien AL, Hughes AD, et al., 2017, The fractal heart - embracing mathematics in the cardiology clinic, Nature Reviews Cardiology, Vol: 14, Pages: 56-64, ISSN: 1759-5002
For clinicians grappling with quantifying the complex spatial and temporal patterns of cardiac structure and function (such as myocardial trabeculae, coronary microvascular anatomy, tissue perfusion, myocyte histology, electrical conduction, heart rate, and blood-pressure variability), fractal analysis is a powerful, but still underused, mathematical tool. In this Perspectives article, we explain some fundamental principles of fractal geometry and place it in a familiar medical setting. We summarize studies in the cardiovascular sciences in which fractal methods have successfully been used to investigate disease mechanisms, and suggest potential future clinical roles in cardiac imaging and time series measurements. We believe that clinical researchers can deploy innovative fractal solutions to common cardiac problems that might ultimately translate into advancements for patient care.
Ahmad T, Bouwman RA, Grigoras I, et al., 2016, Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries., British Journal of Anaesthesia, Vol: 117, Pages: 601-+, ISSN: 0007-0912
BackgroundAs global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care.MethodsWe designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries.ResultsA total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2–7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries.ConclusionsPoor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care.
Raphael CE, Cooper R, Parker KH, et al., 2016, Mechanisms of Myocardial Ischemia in Hypertrophic Cardiomyopathy: Insights From Wave Intensity Analysis and Magnetic Resonance., Journal of the American College of Cardiology, Vol: 68, Pages: 1651-1660, ISSN: 1558-3597
BACKGROUND: Angina is common in hypertrophic cardiomyopathy (HCM) and is associated with abnormal myocardial perfusion. Wave intensity analysis improves the understanding of the mechanics of myocardial ischemia. OBJECTIVES: Wave intensity analysis was used to describe the mechanisms underlying perfusion abnormalities in patients with HCM. METHODS: Simultaneous pressure and flow were measured in the proximal left anterior descending artery in 33 patients with HCM and 20 control patients at rest and during hyperemia, allowing calculation of wave intensity. Patients also underwent quantitative first-pass perfusion cardiac magnetic resonance to measure myocardial perfusion reserve. RESULTS: Patients with HCM had a lower coronary flow reserve than control subjects (1.9 ± 0.8 vs. 2.7 ± 0.9; p = 0.01). Coronary hemodynamics in HCM were characterized by a very large backward compression wave during systole (38 ± 11% vs. 21 ± 6%; p < 0.001) and a proportionately smaller backward expansion wave (27% ± 8% vs. 33 ± 6%; p = 0.006) compared with control subjects. Patients with severe left ventricular outflow tract obstruction had a bisferiens pressure waveform resulting in an additional proximally originating deceleration wave during systole. The proportion of waves acting to accelerate coronary flow increased with hyperemia, and the magnitude of change was proportional to the myocardial perfusion reserve (rho = 0.53; p < 0.01). CONCLUSIONS: Coronary flow in patients with HCM is deranged. Distally, compressive deformation of intramyocardial blood vessels during systole results in an abnormally large backward compression wave, whereas proximally, severe left ventricular outflow tract obstruction is associated with an additional deceleration wave. Perfusion abnormalities in HCM are not simply a consequence of supply/demand mismatch or remodeling of the intramyocardial blood vessels; th
Mereu R, Taraborrelli P, Sau A, et al., 2016, Diagnostic role of head-up tilt test in patients with cough syncope, EUROPACE, Vol: 18, Pages: 1273-1279, ISSN: 1099-5129
Jones S, Lumens J, Sohaib SMA, et al., 2016, Cardiac Resynchronisation Therapy: mechanisms of action and scope for further improvement in cardiac function, Europace, Vol: 19, Pages: 1178-1186, ISSN: 1532-2092
BackgroundCardiac resynchronisation therapy(CRT) may exert its beneficial hemodynamic effect by improving ventricular synchrony and improving atrioventricular(AV) timing.Aims To establish the relative importance of the mechanisms through which CRT improves cardiac function and explore the potential for additional improvements with improved ventricular resynchronisation. Methods We performed simulations using the CircAdapt haemodynamic model and performed haemodynamic measurements while adjusting AV delay, at low and high heart rates, in 87 patients with CRT devices. We assessed QRS duration, presence of fusion and haemodynamic response.ResultsThe simulations suggest intrinsic PR interval and the magnitude of reduction in ventricular activation determine the relative importance of the mechanisms of benefit. For example, if PR interval is 201ms and LV activation time is reduced by 25ms (typical for current CRT methods) then AV delay optimisation is responsible for 69% of overall improvement. Reducing LV activation time by an additional 25ms produced an additional 2.6mmHg increase in BP (30% of effect size observed with current CRT).In the clinical population, ventricular fusion significantly shortened QRS duration (∆-27±23ms, P <0.001), and, improved SBP (mean 2.5 mmHg increase). Ventricular Fusion was present in 69% of patients, yet in 40% of patients with fusion, shortening AV delay (to a delay where fusion was not present) produced the optimal haemodynamic response.ConclusionsImproving LV preloading by shortening AV delay is an important mechanism through which cardiac function is improved with CRT. There is substantial scope for further improvement if methods for delivering more efficient ventricular resynchronisation can be developed.
Ahmad Y, Cook C, Shun-Shin M, et al., 2016, Resolving the paradox of randomised controlled trials and observational studies comparing multi-vessel angioplasty and culprit only angioplasty at the time of STEMI, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 222, Pages: 1-8, ISSN: 0167-5273
Negoita M, Zolgharni M, Dadkho E, et al., 2016, Frame rate required for speckle tracking echocardiography: A quantitative clinical study with open-source, vendor-independent software, International Journal of Cardiology, Vol: 218, Pages: 31-36, ISSN: 1874-1754
ObjectivesTo determine the optimal frame rate at which reliable heart walls velocities can be assessed by speckle tracking.BackgroundAssessing left ventricular function with speckle tracking is useful in patient diagnosis but requires a temporal resolution that can follow myocardial motion. In this study we investigated the effect of different frame rates on the accuracy of speckle tracking results, highlighting the temporal resolution where reliable results can be obtained.Material and methods27 patients were scanned at two different frame rates at their resting heart rate. From all acquired loops, lower temporal resolution image sequences were generated by dropping frames, decreasing the frame rate by up to 10-fold.ResultsTissue velocities were estimated by automated speckle tracking. Above 40 frames/s the peak velocity was reliably measured. When frame rate was lower, the inter-frame interval containing the instant of highest velocity also contained lower velocities, and therefore the average velocity in that interval was an underestimate of the clinically desired instantaneous maximum velocity.ConclusionsThe higher the frame rate, the more accurately maximum velocities are identified by speckle tracking, until the frame rate drops below 40 frames/s, beyond which there is little increase in peak velocity. We provide in an online supplement the vendor-independent software we used for automatic speckle-tracked velocity assessment to help others working in this field.
Sterlinski M, Sokal A, Lenarczyk R, et al., 2016, In Heart Failure Patients with Left Bundle Branch Block Single Lead MultiSpot Left Ventricular Pacing Does Not Improve Acute Hemodynamic Response To Conventional Biventricular Pacing. A Multicenter Prospective, Interventional, Non-Randomized Study, PLOS ONE, Vol: 11, ISSN: 1932-6203
Francis DP, Cole GD, 2016, Authors' reply to Perry., BMJ, Vol: 353, Pages: i2031-i2031, ISSN: 0959-8138
Ghosh AK, Hughes AD, Francis D, et al., 2016, Midlife blood pressure predicts future diastolic dysfunction independently of blood pressure., Heart, Vol: 102, Pages: 1380-1387, ISSN: 1355-6037
OBJECTIVES: High blood pressure (BP) is associated with diastolic dysfunction, but the consequence of elevated BP over the adult life course on diastolic function is unknown. We hypothesised that high BP in earlier adulthood would be associated with impaired diastolic function independent of current BP. METHODS: Participants in the Medical Research Council National Survey of Health and Development birth cohort (n=1653) underwent investigations including echocardiography at age 60-64 years. The relationships between adult BP, antihypertensive treatment (HTT) and echocardiographic measures of diastolic function were assessed using adjusted regression models. RESULTS: Increased systolic BP (SBP) at ages 36, 43 and 53 years was predictive of increased E/e' and increased left atrial volume. These effects were only partially explained by SBP at 60-64 years and increased left ventricular mass. HTT was also associated with poorer diastolic function after adjustment for SBP at 60-64 years. Faster rates of increase in SBP in midlife were also associated with increased poorer diastolic function. CONCLUSIONS: High SBP in midlife is associated with poorer diastolic function at age 60-64 years. Early identification of individuals with high BP or rapid rises in BP may be important for prevention of impaired cardiac function in later life.
Cook CM, Ahmad Y, Shun-Shin MJ, et al., 2016, Quantification of the Effect of Pressure Wire Drift on the Diagnostic Performance of Fractional Flow Reserve, Instantaneous Wave-Free Ratio, and Whole-Cycle Pd/Pa, Circulation: Cardiovascular Interventions, Vol: 9, ISSN: 1941-7640
Background—Small drifts in intracoronary pressure measurements (±2 mmHg) can affect stenosis categorization usingpressure indices. This has not previously been assessed for fractional flow reserve (FFR), instantaneous wave-free ratio(iFR), and whole-cycle distal pressure/proximal pressure (Pd/Pa) indices.Methods and Results—Four hundred forty seven stenoses were assessed with FFR, iFR, and whole-cycle Pd/Pa. Cut pointvalues for significance were predefined as ≤0.8, <0.90, and <0.93, respectively. Pressure wire drift was simulated byoffsetting the distal coronary pressure trace by ±2 mmHg. FFR, iFR, and whole-cycle Pd/Pa indices were recalculatedand stenosis misclassification quantified. Median (±median absolute deviation) values for FFR, iFR, and whole-cycle Pd/Pa were 0.81 (±0.11), 0.90 (±0.07), and 0.93 (±0.06), respectively. 34.6% (155), 50.1% (224), and 62.2% (278) of valueslay within ±0.05 U of the cut point for FFR, iFR, and whole-cycle Pd/Pa, respectively. With ±2 mmHg pressure wire drift,21% (94), 25% (110), and 33% (148) of the study population were misclassified with FFR, iFR, and whole-cycle Pd/Pa,respectively. Both FFR and iFR had significantly lower misclassification than whole-cycle Pd/Pa (P<0.001). There wasno statistically significant difference between the diagnostic performance of FFR and iFR (P=0.125).Conclusions—In a substantial proportion of cases, small amounts of pressure wire drift are enough to causestenoses to change classification. Whole-cycle Pd/Pa is more vulnerable to such reclassification than FFR and iFR.
Francis DP, Cole GD, 2016, Coronary artery disease: screen or treat?, BMJ, Vol: 352, ISSN: 0959-8138
Finegold JA, Shun-Shin M, Cole G, et al., 2016, The distribution of lifespan gain from primary prevention intervention, Open Heart, Vol: 3, ISSN: 2053-3624
Objective: When advising patients about possible initiation of primary prevention treatment, clinicians currently do not have information on expected impact on lifespan, nor how much this increment differs between individuals. Methods: First, UK cardiovascular and non-cardiovascular mortality data was used to calculate the mean lifespan gain from an intervention (such as a statin) that reduces cardiovascular mortality by 30%. Second, a new method was developed to calculate the probability distribution of lifespan gain. Third, we performed a survey in 3 UK cities on 11 days between May-June 2014 involving 396 participants (mean age 40 years, 55% male) to assess how individuals evaluate potential benefit from primary prevention therapies. Results: Amongst numerous identical patients the lifespan gain, from an intervention that reduces cardiovascular mortality by 30%, is concentrated within an unpredictable minority. For example, 50-year-old males with national-average cardiovascular risk have mean lifespan gain of 7 months. However, 93% of these identical individuals gain no lifespan, while the remaining 7% gain a mean of 99 months. Many survey respondents preferred a chance of large lifespan gain to the identical life-expectancy gain given as certainty. Indeed, 33% preferred a 2% probability of 10 years to 5-fold more gain, expressed as certainty of 1 year. Conclusions:People who gain lifespan from preventative therapy gain far more than the average for their risk stratum, even if perfectly defined. This may be important in patient decision-making. Looking beyond mortality reduction alone from preventative therapy, the benefits are likely to be even larger.
Broyd CJ, Nijjer S, Sen S, et al., 2016, Estimation of coronary wave intensity analysis using noninvasive techniques and its application to exercise physiology, AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, Vol: 310, Pages: H619-H627, ISSN: 0363-6135
Barron A, Francis DP, Mayet J, et al., 2016, Oxygen uptake efficiency slope and breathing reserve, not anaerobic threshold, discriminate between patients with cardiovascular disease over COPD, JACC: Heart Failure, Vol: 4, Pages: 252-261, ISSN: 2213-1779
Objectives To compare the relative discrimination of various cardiopulmonary exercise testing (CPX) variables between cardiac and respiratory disease.Background CPX testing is used in many cardiorespiratory diseases. However discrimination of cardiac and respiratory dysfunction can be problematic. Anaerobic threshold (AT) and oxygen-uptake to work-rate relationship (VO2/WR slope) have been proposed as diagnostic of cardiac dysfunction, but multiple variables have not been compared.Methods 73 patients with chronic obstructive airways disease (COPD, n=25), heart failure with reduced ejection fraction (HFrEF, n=40) or combined COPD and HFrEF (n=8), were recruited and underwent CPX testing on a bicycle ergometer. Following a familiarisation test, each patient underwent a personalised second test aiming for maximal exercise after ~10 minutes. Measurements from this test were used to calculate area under receiver-operator characteristic curve (AUC). Results PeakVO2 was similar between the 2 principal groups (COPD 17.1±4.6ml/min/kg (mean±SD), HFrEF 16.4±3.6ml/min/kg). Breathing reserve (AUC 0.91) and percent predicted oxygen uptake efficiency slope (OUES) (AUC 0.87) had the greatest ability to discriminate between COPD and HFrEF. VO2/WR slope performed significantly worse (AUC 0.68). VO2 at the AT did not discriminate (AUC 0.56 for AT as percent predicted peakVO2). OUES and BR remained strong discriminators when compared with an external cohort of healthy matched controls, and were comparable to B-type natriuretic peptide.Conclusions Breathing reserve and OUES discriminate heart failure from COPD. Despite it being considered an important determinant of cardiac dysfunction, the AT could not discriminate these typical clinical populations whilst the VO2/WR slope showed poor to moderate discriminant ability.
Sau A, Mereu R, Taraborrelli P, et al., 2016, A long-term follow-up of patients with prolonged asystole of greater than 15 s on head-up tilt testing, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 203, Pages: 482-485, ISSN: 0167-5273
Howard JP, Shun-Shin MJ, Hartley A, et al., 2016, Quantifying the 3 Biases That Lead to Unintentional Overestimation of the Blood Pressure-Lowering Effect of Renal Denervation., Circulation: Cardiovascular Quality and Outcomes, Vol: 9, Pages: 14-22, ISSN: 1941-7713
BACKGROUND: Studies of renal denervation report disparate results. Meta-analysis by trial design may allow quantitative estimation of sources and magnitude of biases in denervation studies. METHODS AND RESULTS: One hundred forty nonrandomized, 6 randomized open-label, and 2 randomized blinded studies were analyzed for 2 outcomes: (1) blood pressure changes for nonrandomized, open-label randomized, and blinded studies; and (2) quantification of 3 biases potentially contributing to apparent antihypertensive effects: (a) regression to the mean, (b) asymmetrical data handling, and (c) true blood pressure drops caused by something other than the tested therapy (confounding). Nonrandomized studies and open-label randomized trials reported large reductions in office blood pressure of 23.6 mm Hg (95% confidence interval [CI], 22.0 to 25.3) and 29.1 mm Hg (95% CI, 25.2 to 33.1 mm Hg), respectively. They reported smaller reductions in ambulatory blood pressures (11.2 mm Hg; 95% CI, 10.0 to 12.4). The blinded trials found no significant reduction in blood pressure (2.9 mm Hg; 95% CI, -0.4 to 6.3). Analyses of these data indicate the magnitude of the 3 potential sources of bias to be regression to the mean, -1.01 mm Hg (95% CI, 4.24 to -6.27); asymmetrical data handling, -10.8 mm Hg (95% CI, -8.77 to -12.87); and confounding, -8.3 mm Hg (95% CI, -4.73 to -11.83). CONCLUSIONS: Increasingly bias-resistant trial designs report effect sizes of decreasing magnitude. This disparity may be caused by asymmetrical data handling and confounding (eg, increased drug adherence). If these differences are caused by trial design and not by some other differences in patients or procedures, which happen to match the trial design, then randomization alone is not enough: blinding is also needed. This has broad implications across trials of medications and devices.
Petraco R, Sen S, Nijjer S, et al., 2015, ECG-Independent Calculation of Instantaneous Wave-Free Ratio, JACC-CARDIOVASCULAR INTERVENTIONS, Vol: 8, Pages: 2043-2046, ISSN: 1936-8798
Howard JP, Patel H, Shun-Shin MJ, et al., 2015, Impact of number of prescribed medications on visit-to-visit variability of blood pressure: implications for design of future trials of renal denervation, JOURNAL OF HYPERTENSION, Vol: 33, Pages: 2359-2367, ISSN: 0263-6352
Sohaib SMA, Wright I, Lim E, et al., 2015, Atrioventricular Optimized Direct His Bundle Pacing Improves Acute Hemodynamic Function in Patients With Heart Failure and PR Interval Prolongation Without Left Bundle Branch Block, JACC: Clinical electrophysiology, Vol: 1, Pages: 582-591, ISSN: 2405-5018
ObjectivesThe purpose of this study was to investigate whether heart failure patients with narrow QRS duration (or right bundle branch block) but with long PR interval gain acute hemodynamic benefit from atrioventricular (AV) optimization. We tested this with biventricular pacing and (to deliver pure AV shortening) direct His bundle pacing.BackgroundBenefits of pacing for heart failure have previously been indicated by acute hemodynamic studies and verified in outcome studies. A new target for pacing in heart failure may be PR interval prolongation, which is associated with 58% higher mortality regardless of QRS duration.MethodsWe enrolled 16 consecutive patients with systolic heart failure, PR interval prolongation (mean, 254 ± 62 ms) and narrow QRS duration (n = 13; mean QRS duration: 119 ± 17 ms) or right bundle branch block (n = 3; mean, QRS duration: 156 ± 18 ms). We successfully delivered temporary direct His bundle pacing in 14 patients and temporary biventricular pacing in 14 participants. We performed AV optimization using invasive systolic blood pressure obtaining parabolic responses (mean R2: 0.90 for His, and 0.85 for biventricular pacing).ResultsThe mean increment in systolic BP compared with intrinsic ventricular conduction was 4.1 mm Hg (95% confidence interval [CI]: +1.9 to +6.2 mm Hg for His and 4.3 mm Hg [95% CI: +2.0 to +6.5 mm Hg] for biventricular pacing. QRS duration lengthened with biventricular pacing (change = +22 ms [95% CI: +18 to +25 ms]) but not with His pacing (change = +0.5 ms [95% CI: −2.6 to +3.6 ms).ConclusionsAV-optimized pacing improves acute hemodynamic function in patients with heart failure and long PR interval without left bundle branch block. That it can be achieved by single-site His pacing shows that its mechanism is AV shortening. The improvement is ∼60% of the effect size previously reported for biventricular pacing in left bundle branch block. Randomized, blinded trials are warranted to tes
Maznyczka A, Sen S, Cook C, et al., 2015, The ischaemic constellation: an alternative to the ischaemic cascade - implications for the validation of new ischaemic tests, OPEN HEART, Vol: 2, ISSN: 2053-3624
Finegold JA, Francis DP, 2015, What proportion of symptomatic side-effects in patients taking statins are genuinely caused by the drug? A response to letters., Eur J Prev Cardiol, Vol: 22, Pages: 1328-1330
Baksi AJ, Davies JE, Hadjiloizou N, et al., 2015, Attenuation of reflected waves in man during retrograde propagation from femoral artery to proximal aorta, International Journal of Cardiology, Vol: 202, Pages: 441-445, ISSN: 1874-1754
BackgroundWave reflection may be an important influence on blood pressure, but the extent to which reflections undergo attenuation during retrograde propagation has not been studied. We quantified retrograde transmission of a reflected wave created by occlusion of the left femoral artery in man.Methods20 subjects (age 31–83 years; 14 male) underwent invasive measurement of pressure and flow velocity with a sensor-tipped intra-arterial wire at multiple locations distal to the proximal aorta before, during and following occlusion of the left femoral artery by thigh cuff inflation. A numerical model of the circulation was also used to predict reflected wave transmission. Wave reflection was measured as the ratio of backward to forward wave energy (WRI) and the ratio of peak backward to forward pressure (Pb/Pf).ResultsCuff inflation caused a marked reflection which was largest at 5–10 cm from the cuff (change (Δ) in WRI = 0.50 (95% CI 0.38, 0.62); p < 0.001, ΔPb/Pf = 0.23 (0.18–0.29); p < 0.001). The magnitude of the cuff-induced reflection decreased progressively at more proximal locations and was barely discernible at sites > 40 cm from the cuff including in the proximal aorta. Numerical modelling gave similar predictions to those observed experimentally.ConclusionsReflections due to femoral artery occlusion are markedly attenuated by the time they reach the proximal aorta. This is due to impedance mismatches of bifurcations traversed in the backward direction. This degree of attenuation is inconsistent with the idea of a large discrete reflected wave arising from the lower limb and propagating back into the aorta.
Cole GD, Nowbar A, Mielewczik M, et al., 2015, Frequency of discrepancies in retracted clinical trial reports versus unretracted reports: blinded case-control study, British Medical Journal, Vol: 351, ISSN: 1468-5833
Objectives To compare the frequency of discrepancies in retracted reports of clinical trials with those in adjacent unretracted reports in the same journal.Design Blinded case-control study.Setting Journals in PubMed.Population 50 manuscripts, classified on PubMed as retracted clinical trials, paired with 50 adjacent unretracted manuscripts from the same journals. Reports were randomly selected from PubMed in December 2012, with no restriction on publication date. Controls were the preceding unretracted clinical trial published in the same journal. All traces of retraction were removed. Three scientists, blinded to the retraction status of individual reports, reviewed all 100 trial reports for discrepancies. Discrepancies were pooled and cross checked before being counted into prespecified categories. Only then was the retraction status unblinded for analysis.Main outcome measure Total number of discrepancies (defined as mathematically or logically contradictory statements) in each clinical trial report.Results Of 479 discrepancies found in the 100 trial reports, 348 were in the 50 retracted reports and 131 in the 50 unretracted reports. On average, individual retracted reports had a greater number of discrepancies than unretracted reports (median 4 (interquartile range 2-8.75) v 0 (0-5); P<0.001). Papers with a discrepancy were significantly more likely to be retracted than those without a discrepancy (odds ratio 5.7 (95% confidence interval 2.2 to 14.5); P<0.001). In particular, three types of discrepancy arose significantly more frequently in retracted than unretracted reports: factual discrepancies (P=0.002), arithmetical errors (P=0.01), and missed P values (P=0.02). Results from a retrospective analysis indicated that citations and journal impact factor were unlikely to affect the result.Conclusions Discrepancies in published trial reports should no longer be assumed to be unimportant. Scientists, blinded to retraction status and with no specialist skill
Ahmad Y, Nijjer S, Cook CM, et al., 2015, A new method of applying randomised control study data to the individual patient: A novel quantitative patient-centred approach to interpreting composite end points, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 195, Pages: 216-224, ISSN: 0167-5273
Dehbi H-M, Jones S, Sohaib SMA, et al., 2015, A novel curve fitting method for AV optimisation of biventricular pacemakers, PHYSIOLOGICAL MEASUREMENT, Vol: 36, Pages: 1889-1900, ISSN: 0967-3334
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