A comparison of flow rate curve shape and video-urodynamic findings in women with lower urinary tract symptoms: can flow rate curve shape predict female bladder outflow obstruction or detrusor underactivity?

PURPOSE: To establish the correlation between flow rate curve shape and video-urodynamic findings in women with lower urinary tract symptoms (LUTS). METHODS: A retrospective review of consecutive women with LUTS who performed a free flow study immediately before undergoing video-urodynamic investigations over a 28-month period. Flow rate curve shape and video-urodynamic parameters were analysed. Free flow curves were defined into five categories: bell-shaped, prolonged, fluctuating, intermittent or plateau. Women who voided less than 150 ml on the free flow study were excluded from the analysis. RESULTS: A total of 250 women with LUTS, with a mean age 48 years (range 18-83), were included. Bell-shaped tracings excluded obstruction in 89%. Prolonged flow rate curves diagnosed obstruction in 62% and detrusor underactivity in 8%. Fluctuating and intermittent flow rate curves were associated with urodynamic obstruction in 37 and 39%, respectively, and detrusor underactivity in 25 and 29%, respectively. A plateau flow rate curve was indicative of urodynamic obstruction in all three cases observed. CONCLUSION: Flow rate curve patterns can be suggestive of urodynamic diagnoses. Women without a prolonged void and bell-shaped traces had normal voiding urodynamics in 76% of cases, and the majority could be managed without invasive investigations. Patients with fluctuating and intermittent flow rate curves demonstrate a spectrum of urodynamic diagnoses with a third of cases having obstruction and a third of cases having detrusor underactivity. Plateau flow rate curve patterns are associated with urethral obstruction.

Pad weight gain in asymptomatic continent women is far less than the current ICS definition.

AIMS: To investigate typical pad weight gain (PWG) in asymptomatic women who have never reported any episodes of urinary incontinence. METHODS: An observational study was performed by measuring the increase in weight of small sanitary pads worn by 35 healthy, female volunteers of a median age 36 (range, 23-56) years. Each pad was worn for a minimum of 5 h which is the typical maximum duration of an ambulatory urodynamics study. RESULTS: The median duration of pad wear was 6 h (interquartile range [IQR], 5-8). The median PWG was 0.111 g (IQR, 0.047-0.255). The maximum recorded PWG was 0.621 g and the minimum was 0.012 g. PWG was not significantly affected by age, parity, years since last delivery, body mass index, or menopausal status. CONCLUSIONS: PWG over a median duration of 6 h (IQR, 5-8) is typically <0.7 g in women who are asymptomatic of urinary incontinence. Therefore, PWGs in excess of 0.7 g over a 5-h ambulatory urodynamics study in symptomatic women are likely to be diagnostic of urinary incontinence.

Right ventriculo-arterial uncoupling and impaired contractile reserve in obese patients with unexplained exercise intolerance.

BACKGROUND: Right ventricular (RV) dysfunction and heart failure with preserved ejection fraction may contribute to exercise intolerance in obesity. To further define RV exercise responses, we investigated RV-arterial coupling in obesity with and without development of exercise pulmonary venous hypertension (ePVH). METHODS: RV-arterial coupling defined as RV end-systolic elastance/pulmonary artery elastance (Ees/Ea) was calculated from invasive cardiopulmonary exercise test data in 6 controls, 8 obese patients without ePVH (Obese-ePVH) and 8 obese patients with ePVH (Obese+ePVH) within a larger series. ePVH was defined as a resting pulmonary arterial wedge pressure < 15 mmHg but ≥ 20 mmHg on exercise. Exercise haemodynamics were further evaluated in 18 controls, 20 Obese-ePVH and 17 Obese+ePVH patients. RESULTS: Both Obese-ePVH and Obese+ePVH groups developed exercise RV-arterial uncoupling (peak Ees/Ea = 1.45 ± 0.26 vs 0.67 ± 0.18 vs 0.56 ± 0.11, p < 0.001, controls vs Obese-ePVH vs Obese+ePVH respectively) with higher peak afterload (peak Ea = 0.31 ± 0.07 vs 0.75 ± 0.32 vs 0.88 ± 0.62 mL/mmHg, p = 0.043) and similar peak contractility (peak Ees = 0.50 ± 0.16 vs 0.45 ± 0.22 vs 0.48 ± 0.17 mL/mmHg, p = 0.89). RV contractile reserve was highest in controls (ΔEes = 224 ± 80 vs 154 ± 39 vs 141 ± 34% of baseline respectively, p < 0.001). Peak Ees/Ea correlated with peak pulmonary vascular compliance (PVC, r = 0.53, p = 0.02) but not peak pulmonary vascular resistance (PVR, r = - 0.20, p = 0.46). In the larger cohort, Obese+ePVH patients on exercise demonstrated higher right atrial pressure, lower cardiac output and steeper pressure-flow responses. BMI correlated with peak PVC (r = - 0.35, p = 0.04) but not with peak PVR (r = 0.24, p = 0.25). CONCLUSIONS: Exercise RV-arterial uncoupling and reduced RV contractile reserve further characterise obesity-related exercise intolerance. RV dysfunction in obesity may develop independent of exercise LV filling pressures.

Glucagon-like peptide-1 derived cardioprotection does not utilize a KATP-channel dependent pathway: mechanistic insights from human supply and demand ischemia studies.

BACKGROUND: Glucagon-like peptide-1 (7-36) amide (GLP-1) protects against stunning and cumulative left ventricular dysfunction in humans. The mechanism remains uncertain but GLP-1 may act by opening mitochondrial K-ATP channels in a similar fashion to ischemic conditioning. We investigated whether blockade of K-ATP channels with glibenclamide abrogated the protective effect of GLP-1 in humans. METHODS: Thirty-two non-diabetic patients awaiting stenting of the left anterior descending artery (LAD) were allocated into 4 groups (control, glibenclamide, GLP-1, and GLP-1 + glibenclamide). Glibenclamide was given orally prior to the procedure. A left ventricular conductance catheter recorded pressure-volume loops during a 1-min low-pressure balloon occlusion (BO1) of the LAD. GLP-1 or saline was then infused for 30-min followed by a further 1-min balloon occlusion (BO2). In a non-invasive study, 10 non-diabetic patients were randomized to receive two dobutamine stress echocardiograms (DSE) during GLP-1 infusion with or without oral glibenclamide pretreatment. RESULTS: GLP-1 prevented stunning even with glibenclamide pretreatment; the Δ % dP/dtmax 30-min post-BO1 normalized to baseline after GLP-1: 0.3 ± 6.8 % (p = 0.02) and GLP-1 + glibenclamide: -0.8 ± 9.0 % (p = 0.04) compared to control: -11.5 ± 10.0 %. GLP-1 also reduced cumulative stunning after BO2: -12.8 ± 10.5 % (p = 0.02) as did GLP-1 + glibenclamide: -14.9 ± 9.2 % (p = 0.02) compared to control: -25.7 ± 9.6 %. Glibenclamide alone was no different to control. Glibenclamide pretreatment did not affect global or regional systolic function after GLP-1 at peak DSE stress (EF 74.6 ± 6.4 vs. 74.0 ± 8.0, p = 0.76) or recovery (EF 61.9 ± 5.7 vs. 61.4 ± 5.6, p = 0.74). CONCLUSIONS: Glibenclamide pretreatment does not abrogate the protective effect of GLP-1 in human models of non-lethal myocardial ischemia. Trial registration Clinicaltrials.gov Unique Identifier: NCT02128022.

RV diastolic dysfunction: time to re-evaluate its importance in heart failure.

Right ventricular (RV) diastolic dysfunction was first reported as an indicator for the assessment of ventricular dysfunction in heart failure a little over two decades ago. However, the underlying mechanisms and precise role of RV diastolic dysfunction in heart failure remain poorly described. Complexities in the structure and function of the RV make the detailed assessment of the contractile performance challenging when compared to its left ventricular (LV) counterpart. LV dysfunction is known to directly affect patient outcome in heart failure. As such, the focus has therefore been on LV function. Nevertheless, a strategy for the diagnosis and assessment of RV diastolic dysfunction has not been established. Here, we review the different causal mechanisms underlying RV diastolic dysfunction, summarising the current assessment techniques used in a clinical environment. Finally, we explore the role of load-independent indices of RV contractility, derived from the conductance technique, to fully interrogate the RV and expand our knowledge and understanding of RV diastolic dysfunction. Accurate assessment of RV contractility may yield further important prognostic information that will benefit patients with diastolic heart failure.

Prostate cancer: performance characteristics of combined T2W and DW-MRI scoring in the setting of template transperineal re-biopsy using MR-TRUS fusion.

OBJECTIVES: To measure the performance characteristics of combined T2-weighted (T2W) and diffusion-weighted (DW) magnetic resonance imaging (MRI) suspicion scoring prior to MR-transrectal ultrasound (TRUS) fusion template transperineal (TTP) re-biopsy. METHODS: Thirty-nine patients referred for prostate re-biopsy, with prior MRI examinations, were retrospectively included. The MR images, including T2W and DW-MRI, had been independently evaluated prospectively by two radiologists using a structured scoring system. An MR-TRUS fusion TTP re-biopsy was used for MR target and non-targeted biopsy cores. Targeting performance and correlation with disease status were evaluated on a per-patient and per-region basis. RESULTS: The cancer yield was 41% (16/39 patients). MR targeting accurately detected the disease in 12/16 (75%) cancerous patients and missed the disease in 4/16 (25%) patients, all with Gleason 3 + 3 disease. There was a significant relationship (P < 0.01) between MR suspicion score and the significance of cancer. Reader 1 had significantly higher sensitivity in the transition zone (TZ; 0.84) compared with the peripheral zone (PZ; 0.32) (P = 0.04). Inter-reader agreement was moderate for the PZ and substantial for the TZ. CONCLUSIONS: MRI targeting is beneficial in the setting of TTP MR-TRUS fusion re-biopsy and MR suspicion score relates to prostate cancer clinical significance. A T2W and DW-MRI structured scoring system results in good inter-reader agreement in this setting. KEY POINTS: • Pre-biopsy MRI aids the detection of high significance cancer during prostate re-biopsy. • MRI suspicion level correlates with the clinical significance of prostate cancer detected. • T2W and DW-MRI structured scoring of pre-biopsy MRI permits good inter-reader agreement.

Definitions of terms, processes and a minimum dataset for transperineal prostate biopsies: a standardization approach of the Ginsburg Study Group for Enhanced Prostate Diagnostics.

OBJECTIVES: To define terms and processes and agree on a minimum dataset in relation to transperineal prostate biopsy procedures and enhanced prostate diagnostics. To identify the need for further evaluation and establish a collaborative research practice. PATIENTS AND METHODS: A 19-member multidisciplinary panel rated 66 items for their appropriateness and their definition to be incorporated into the international databank using the Research and Development/University of California Los Angeles Appropriateness Method. The item list was developed from interviews conducted with healthcare professionals from urology, radiology, pathology and engineering. RESULTS: The panel agreed on 56 items that were appropriate to be incorporated into a prospective database. In total, 10 items were uncertain and were omitted. These items were within the categories: definitions (n = 2), imaging (n = 1), surgical protocols (n = 2) and histology (n = 5). CONCLUSIONS: The components of a minimum dataset for transperineal prostate biopsy have been defined. This provides an opportunity for multicentre collaborative data analysis and technique development. The findings of the present study will facilitate prospective studies into the application and outcome of transperineal prostate biopsies.

In vitro characterisation of ultrasound-induced heating effects in the mother and fetus: A clinical perspective.

INTRODUCTION: The quantification of heating effects during exposure to ultrasound is usually based on laboratory experiments in water and is assessed using extrapolated parameters such as the thermal index. In our study, we have measured the temperature increase directly in a simulator of the maternal-fetal environment, the 'ISUOG Phantom', using clinically relevant ultrasound scanners, transducers and exposure conditions. METHODS: The study was carried out using an instrumented phantom designed to represent the pregnant maternal abdomen and which enabled temperature recordings at positions in tissue mimics which represented the skin surface, sub-surface, amniotic fluid and fetal bone interface. We tested four different transducers on a commercial diagnostic scanner. The effects of scan duration, presence of a circulating fluid, pre-set and power were recorded. RESULTS: The highest temperature increase was always at the transducer-skin interface, where temperature increases between 1.4°C and 9.5°C were observed; lower temperature rises, between 0.1°C and 1.0°C, were observed deeper in tissue and at the bone interface. Doppler modes generated the highest temperature increases. Most of the heating occurred in the first 3 minutes of exposure, with the presence of a circulating fluid having a limited effect. The power setting affected the maximum temperature increase proportionally, with peak temperature increasing from 4.3°C to 6.7°C when power was increased from 63% to 100%. CONCLUSIONS: Although this phantom provides a crude mimic of the in vivo conditions, the overall results showed good repeatability and agreement with previously published experiments. All studies showed that the temperature rises observed fell within the recommendations of international regulatory bodies. However, it is important that the operator should be aware of factors affecting the temperature increase.

Glucagon-Like Peptide-1-Mediated Cardioprotection Does Not Reduce Right Ventricular Stunning and Cumulative Ischemic Dysfunction After Coronary Balloon Occlusion.

Stunning and cumulative ischemic dysfunction occur in the left ventricle with coronary balloon occlusion. Glucagon-like peptide (GLP)-1 protects the left ventricle against this dysfunction. This study used a conductance catheter method to evaluate whether the right ventricle (RV) developed similar dysfunction during right coronary artery balloon occlusion and whether GLP-1 was protective. In this study, the RV underwent significant stunning and cumulative ischemic dysfunction with right coronary artery balloon occlusion. However, GLP-1 did not protect the RV against this dysfunction when infused after balloon occlusion.

Human heart transplantation from donation after circulatory-determined death donors using normothermic regional perfusion and cold storage.

Heart transplantation from donation after circulatory-determined-death (DCD) donors is emerging as an additional avenue to increase heart transplant activity. Previous methods of DCD heart retrieval include direct procurement and cold storage, direct procurement, and machine perfusion and normothermic regional perfusion, followed by machine perfusion during transportation. Herein we report a further technique resulting in successful DCD heart transplantation utilizing normothermic regional perfusion and permitting functional assessment followed by cold storage.

Stunning and Right Ventricular Dysfunction Is Induced by Coronary Balloon Occlusion and Rapid Pacing in Humans: Insights From Right Ventricular Conductance Catheter Studies.

BACKGROUND: We sought to determine whether right ventricular stunning could be detected after supply (during coronary balloon occlusion [BO]) and supply/demand ischemia (induced by rapid pacing [RP] during transcatheter aortic valve replacement) in humans. METHODS AND RESULTS: Ten subjects with single-vessel right coronary artery disease undergoing percutaneous coronary intervention with normal ventricular function were studied in the BO group. Ten subjects undergoing transfemoral transcatheter aortic valve replacement were studied in the RP group. In both, a conductance catheter was placed into the right ventricle, and pressure volume loops were recorded at baseline and for intervals over 15 minutes after a low-pressure BO for 1 minute or a cumulative duration of RP for up to 1 minute. Ischemia-induced diastolic dysfunction was seen 1 minute after RP (end-diastolic pressure [mm Hg]: 8.1±4.2 versus 12.1±4.1, P<0.001) and BO (end-diastolic pressure [mm Hg]: 8.1±4.0 versus 8.7±4.0, P=0.03). Impairment of systolic and diastolic function after BO remained at 15-minutes recovery (ejection fraction [%]: 55.7±9.0 versus 47.8±6.3, P<0.01; end-diastolic pressure [mm Hg]: 8.1±4.0 versus 9.2±3.9, P<0.01). Persistent diastolic dysfunction was also evident in the RP group at 15-minutes recovery (end-diastolic pressure [mm Hg]: 8.1±4.1 versus 9.9±4.4, P=0.03) and there was also sustained impairment of load-independent indices of systolic function at 15 minutes after RP (end-systolic elastance and ventriculo-arterial coupling [mm Hg/mL]: 1.25±0.31 versus 0.85±0.43, P<0.01). CONCLUSIONS: RP and right coronary artery balloon occlusion both cause ischemic right ventricular dysfunction with stunning observed later during the procedure. This may have intraoperative implications in patients without right ventricular functional reserve.

Ventriculo-arterial coupling detects occult RV dysfunction in chronic thromboembolic pulmonary vascular disease.

Chronic thromboembolic disease (CTED) is suboptimally defined by a mean pulmonary artery pressure (mPAP) <25 mmHg at rest in patients that remain symptomatic from chronic pulmonary artery thrombi. To improve identification of right ventricular (RV) pathology in patients with thromboembolic obstruction, we hypothesized that the RV ventriculo-arterial (Ees/Ea) coupling ratio at maximal stroke work (Ees/Eamax sw) derived from an animal model of pulmonary obstruction may be used to identify occult RV dysfunction (low Ees/Ea) or residual RV energetic reserve (high Ees/Ea). Eighteen open chested pigs had conductance catheter RV pressure-volume (PV)-loops recorded during PA snare to determine Ees/Eamax sw This was then applied to 10 patients with chronic thromboembolic pulmonary hypertension (CTEPH) and ten patients with CTED, also assessed by RV conductance catheter and cardiopulmonary exercise testing. All patients were then restratified by Ees/Ea. The animal model determined an Ees/Eamax sw = 0.68 ± 0.23 threshold, either side of which cardiac output and RV stroke work fell. Two patients with CTED were identified with an Ees/Ea well below 0.68 suggesting occult RV dysfunction whilst three patients with CTEPH demonstrated Ees/Ea ≥ 0.68 suggesting residual RV energetic reserve. Ees/Ea > 0.68 and Ees/Ea < 0.68 subgroups demonstrated constant RV stroke work but lower stroke volume (87.7 ± 22.1 vs. 60.1 ± 16.3 mL respectively, P = 0.006) and higher end-systolic pressure (36.7 ± 11.6 vs. 68.1 ± 16.7 mmHg respectively, P < 0.001). Lower Ees/Ea in CTED also correlated with reduced exercise ventilatory efficiency. Low Ees/Ea aligns with features of RV maladaptation in CTED both at rest and on exercise. Characterization of Ees/Ea in CTED may allow for better identification of occult RV dysfunction.

Outcome after heart transplantation from donation after circulatory-determined death donors.

BACKGROUND: The requirement for heart transplantation is increasing, vastly outgrowing the supply of hearts available from donation after brain death (DBD) donors. Transplanting hearts after donation after circulatory-determined death (DCD) may be a viable additive alternative to DBD donors. This study compared outcomes from the largest single-center experience of DCD heart transplantation against matched DBD heart transplants. METHODS: DCD hearts were retrieved using normothermic regional perfusion (NRP) or direct procurement and perfusion (DPP). During NRP, perfusion was restored to the arrested heart within the donor with the exclusion of the cerebral circulation, whereas DPP hearts were removed directly. All hearts were maintained on machine perfusion during transportation. A retrospective cohort of DBD heart transplants, matched for donor and recipient characteristics, was used as a comparison group. The primary outcome measure of this study (set by the United Kingdom regulatory body) was 90-day survival. RESULTS: There were 28 DCD heart transplants performed during the 25-month study period. Survival at 90 days was not significantly different between DCD and matched DBD transplant recipients (DCD, 92%; DBD, 96%; p = 1.0). Hospital length of stay, treated rejection episodes, allograft function, and 1-year survival (DCD, 86%; DBD, 88%; p = 0.98) were comparable between groups. The method of retrieval (NRP or DPP) was not associated with a difference in outcome. CONCLUSIONS: These results suggest that heart transplantation from DCD heart donation provides comparable short-term outcomes to traditional DBD heart transplants and can serve to increase heart transplant activity in well-selected patients.

Functional assessment and transplantation of the donor heart after circulatory death.

BACKGROUND: After a severe shortage of brain-dead donors, the demand for heart transplantation has never been greater. In an attempt to increase organ supply, abdominal and lung transplant programs have turned to the donation after circulatory-determined death (DCD) donor. However, because heart function cannot be assessed after circulatory death, DCD heart transplantation was deemed high risk and never adopted routinely. We report a novel method of functional assessment of the DCD heart resulting in a successful clinical program. METHODS: Normothermic regional perfusion (NRP) was used to restore function to the arrested DCD heart within the donor after exclusion of the cerebral circulation. After weaning from support, DCD hearts underwent functional assessment with cardiac-output studies, echocardiography, and pressure-volume loops. In the feasibility phase, hearts were transported perfused before evaluation of function in modified working mode extracorporeally. After the establishment of a reliable assessment technique, hearts with demonstrable good function were then selected for clinical transplantation. RESULTS: NRP was instituted in 13 adult DCD donors, median age of 33 years (interquartile range [IQR], 28-38 years), after a median ischemic time from withdrawal to perfusion of 24 minutes (IQR, 21-29; range, 17-146 minutes). Two of 4 hearts in the feasibility phase were unsuitable for transplantation after functional assessment. Nine DCD hearts were transplanted in the clinical phase, with 100% survival. The median intensive care duration was 5 days (IQR, 4-5 days), with 2 patients requiring mechanical support. There were no episodes of rejection (total, 1,436 patient-days; range, 48-297). During the same period, we performed 20 standard heart transplants using brain-dead donors. CONCLUSIONS: NRP allows rapid reperfusion and functional assessment of the DCD donor heart, ensuring only viable hearts are selected for transplantation. This technique minimizes the risk of primary graft dysfunction and maximizes confidence in DCD heart transplantation, realizing a 45% increase in our heart transplant activity.

Pre-treatment with glucagon-like Peptide-1 protects against ischemic left ventricular dysfunction and stunning without a detected difference in myocardial substrate utilization.

OBJECTIVES: This study sought to determine whether pre-treatment with intravenous glucagon-like peptide-1 (GLP-1)(7-36) amide could alter myocardial glucose use and protect the heart against ischemic left ventricular (LV) dysfunction during percutaneous coronary intervention. BACKGROUND: GLP-1 has been shown to have favorable cardioprotective effects, but its mechanisms of action remain unclear. METHODS: Twenty patients with preserved LV function and single-vessel left anterior descending coronary artery disease undergoing elective percutaneous coronary intervention were studied. A conductance catheter was placed into the LV, and pressure-volume loops were recorded at baseline, during 1-min low-pressure balloon occlusion (BO), and at 30-min recovery. Patients were randomized to receive an infusion of either GLP-1(7-36) amide at 1.2 pmol/kg/min or saline immediately after baseline measurements. Simultaneous coronary artery and coronary sinus blood sampling was performed at baseline and after BO to assess transmyocardial glucose concentration gradients. RESULTS: BO caused both ischemic LV dysfunction and stunning in the control group but not in the GLP-1 group. Compared with control subjects, the GLP-1 group had a smaller reduction in LV performance during BO (delta dP/dTmax, -4.3 vs. -19.0%, p = 0.02; delta stroke volume, -7.8 vs. -26.4%, p = 0.05), and improved LV performance at 30-min recovery. There was no difference in transmyocardial glucose concentration gradients between the 2 groups. CONCLUSIONS: Pre-treatment with GLP-1(7-36) amide protects the heart against ischemic LV dysfunction and improves the recovery of function during reperfusion. This occurs without a detected change in myocardial glucose extraction and may indicate a mechanism of action independent of an effect on cardiac substrate use. (Effect of Glucgon-Like-Peptide-1 [GLP-1] on Left Ventricular Function During Percutaneous Coronary Intervention [PCI]; ISRCTN77442023).

Right ventricular dysfunction in chronic thromboembolic obstruction of the pulmonary artery: a pressure-volume study using the conductance catheter.

Pressure-volume loops describe dynamic ventricular performance, relevant to patients with and at risk of pulmonary hypertension. We used conductance catheter-derived pressure-volume loops to measure right ventricular (RV) mechanics in patients with chronic thromboembolic pulmonary arterial obstruction at different stages of pathological adaptation. Resting conductance catheterization was performed in 24 patients: 10 with chronic thromboembolic pulmonary hypertension (CTEPH), 7 with chronic thromboembolic disease without pulmonary hypertension (CTED), and 7 controls. To assess the validity of conductance measurements, RV volumes were compared in a subset of 8 patients with contemporaneous cardiac magnetic resonance (CMR). Control, CTED, and CTEPH groups showed different pressure-volume loop morphology, most notable during systolic ejection. Prolonged diastolic relaxation was seen in patients with CTED and CTEPH [tau = 56.2 ± 6.7 (controls) vs. 69.7 ± 10.0 (CTED) vs. 67.9 ± 6.2 ms (CTEPH), P = 0.02]. Control and CTED groups had lower afterload (Ea) and contractility (Ees) compared with the CTEPH group (Ea = 0.30 ± 0.10 vs. 0.52 ± 0.24 vs. 1.92 ± 0.70 mmHg/ml, respectively, P < 0.001) (Ees = 0.44 ± 0.20 vs. 0.59 ± 0.15 vs. 1.13 ± 0.43 mmHg/ml, P < 0.01) with more efficient ventriculoarterial coupling (Ees/Ea = 1.46 ± 0.30 vs. 1.27 ± 0.36 vs. 0.60 ± 0.18, respectively, P < 0.001). Stroke volume assessed by CMR and conductance showed closest agreement (mean bias +9 ml, 95% CI -1 to +19 ml) compared with end-diastolic volume (+48 ml, -16 to 111 ml) and end-systolic volume (+37 ml, -21 to 94 ml). RV conductance catheterization detects novel alteration in pressure-volume loop morphology and delayed RV relaxation in CTED, which distinguish this group from controls. The observed agreement in stroke volume assessed by CMR and conductance suggests RV mechanics are usefully measured by conductance catheter in chronic thromboembolic obstruction.

A novel method for more accurately mapping the surface temperature of ultrasonic transducers.

This paper introduces a novel method for measuring the surface temperature of ultrasound transducer membranes and compares it with two standard measurement techniques. The surface temperature rise was measured as defined in the IEC Standard 60601-2-37. The measurement techniques were (i) thermocouple, (ii) thermal camera and (iii) novel infra-red (IR) "micro-sensor." Peak transducer surface measurements taken with the thermocouple and thermal camera were -3.7 ± 0.7 (95% CI)°C and -4.3 ± 1.8 (95% CI)°C, respectively, within the limits of the IEC Standard. Measurements taken with the novel IR micro-sensor exceeded these limits by 3.3 ± 0.9 (95% CI)°C. The ambiguity between our novel method and the standard techniques could have direct patient safety implications because the IR micro-sensor measurements were beyond set limits. The spatial resolution of the measurement technique is not well defined in the IEC Standard and this has to be taken into consideration when selecting which measurement technique is used to determine the maximum surface temperature.