Fluid-filled Catheter Research Articles

Dapagliflozin enhances arterial and venous compliance during exercise in heart failure with preserved ejection fraction

Abstract Background Systemic arterial compliance and venous capacitance are typically impaired in patients with heart failure with preserved ejection fraction (HFpEF), contributing to hemodynamic congestion with stress. Sodium-glucose cotransporter-2 inhibitors (SGLT2i) reduce hemodynamic congestion and improve clinical outcomes in patients with HFpEF, but the mechanisms remain unclear. Purpose This study tested the hypothesis that SGLT2i dapagliflozin would improve systemic arterial compliance and venous capacitance during exercise in patients with HFpEF. Methods In this secondary analysis from the RCT trial, patients with HFpEF underwent invasive hemodynamic exercise testing at baseline and following treatment for 24 weeks with dapagliflozin or placebo. Patients were required to display pulmonary capillary wedge pressure (PCWP) ≥25 mmHg during exercise at the time of baseline evaluation. Radial artery pressure (BP) was measured continuously using a fluid-filled catheter with transformation to aortic pressure, central hemodynamics were measured using high-fidelity micromanometers, and stressed blood volume was estimated (eSBV) from hemodynamic indices fit to a comprehensive cardiovascular model. Results A total of 37 patients completed the study and were included in this analysis (21 dapagliflozin and 16 placebo). Patients were predominantly women (24/37, 65%) and older (mean age 67 years). There was no statistically significant effect of dapagliflozin on resting BP, but dapagliflozin reduced systolic BP during peak exercise (estimated treatment difference [ETD], -18.8 mmHg, 95% CI: -33.9 to -3.7, P=0.016) (Figure 1A). Dapagliflozin improved exertional total arterial compliance (TAC) index (ETD, 0.06 mL/mmHg/m2, 95% CI: 0.003 to 0.11, P=0.039) (Figure 1B) and aortic root characteristic impedance (ETD, -2.6 mmHg/ml*sec, 95% CI: -5.1 to -0.03, P=0.048) during peak exercise, with no significant effect on systemic vascular resistance. Dapagliflozin reduced eSBV at rest and during peak exercise (ETD, -292 mmHg, 95% CI: -530 to -53, P=0.018) (Figure 1C), and improved venous capacitance evidenced by a decline in ratio of eSBV to total blood volume (ETD, -7.3%, 95% CI -13.3 to -1.3, P=0.020). Each of these effects of dapagliflozin during peak exercise were also observed during matched 20W exercise intensity. Improvements in TAC index and eSBV were correlated with decreases in body weight, and reduction in systolic BP with treatment was correlated with the change in eSBV during exercise (r=0.40, P=0.019) (Figure 2A). Decreases in BP were correlated with reduction in PCWP during exercise (r=0.56, P<0.001) (Figure 2B). Conclusion In patients with HFpEF, treatment with dapagliflozin improved systemic arterial compliance and venous capacitance during exercise, while reducing aortic characteristic impedance, suggesting a reduction in arterial wall stiffness. These vascular effects may partially explain the clinical benefits with SGLT2i in HFpEF.

O31 VALIDATION ASSESSMENT OF A CUFF-BASED CENTRAL BLOOD PRESSURE DEVICE ACCORDING TO ARTERY SOCIETY RECOMMENDATIONS

Background and objective. Uscom BP+ is a cuff-based blood pressure (BP) device designed to non-invasively estimate central BP as distinct from conventional brachial BP. This study aimed to assess the accuracy of the Uscom BP+ device compared to invasively measured BP. Methods. Automated non-invasive cuff central BP (using the Uscom BP+ device) and invasive central aortic BP (using fluid-filled catheters) were recorded simultaneously in 191 participants (65% male, aged 66±11 years) receiving coronary angiography at three independent research sites (Hobart, Australia, Perugia, Italy and Wroclaw, Poland). Validation assessment procedures were undertaken according to the Artery Society recommendations and with a minimal acceptable error of ≤5±≤8 mmHg as pass criteria. Results. Using the device default calibration technique (brachial cuff systolic [SBP] and diastolic BP [DBP]), cuff central SBP underestimated invasive central SBP [mean(SD) difference: -10.2(11.2) mmHg] and cuff central DBP overestimated invasive central DBP [mean(SD) difference: 9.7(8.6) mmHg]. When calibrating by cuff mean arterial pressure and DBP in a sub-group (n=140), SBP accuracy was improved, but variability remained high [mean(SD) difference: -6.4(13.8) mmHg, p=0.002 vs default calibration], whereas DBP accuracy and variability remained similar [mean(SD) difference: 9.0(8.4) mmHg, p=0.23 vs default calibration]. Conclusions. The Uscom BP+ cuff device does not pass the Artery Society accuracy criteria compared with invasively measured central BP.

Dapagliflozin Enhances Arterial and Venous Compliance During Exercise in Heart Failure With Preserved Ejection Fraction: Insights From the CAMEO-DAPA Trial.

Systemic arterial compliance and venous capacitance are typically impaired in patients with heart failure with preserved ejection fraction (HFpEF), contributing to hemodynamic congestion with stress. Sodium-glucose cotransporter-2 inhibitors reduce hemodynamic congestion and improve clinical outcomes in patients with HFpEF, but the mechanisms remain unclear. This study tested the hypothesis that Dapagliflozin would improve systemic arterial compliance and venous capacitance during exercise in patients with HFpEF. In this secondary analysis from the CAMEO-DAPA trial (Cardiac and Metabolic Effects of Dapagliflozin in Heart Failure With Preserved Ejection Fraction Trial), 37 patients with HFpEF (mean age 68 ± 9 years, women 65%) underwent invasive hemodynamic exercise testing with simultaneous echocardiography at baseline and following treatment for 24 weeks with Dapagliflozin or placebo. Radial artery pressure (BP) was measured continuously using a fluid-filled catheter with transformation to aortic pressure, central hemodynamics were measured using high-fidelity micromanometers, and stressed blood volume was estimated from hemodynamic indices fit to a comprehensive cardiovascular model. There was no statistically significant effect of Dapagliflozin on resting BP, but Dapagliflozin reduced systolic BP during peak exercise (estimated treatment difference [ETD], -18.8 mm Hg [95% CI, -33.9 to -3.7] P=0.016). Reduction in BP was related to improved exertional total arterial compliance (ETD, 0.06 mL/mm Hg/m2 [95% CI, 0.003-0.11] P=0.039) and aortic root characteristic impedance (ETD, -2.6 mm Hg/mL*sec [95% CI: -5.1 to -0.03] P=0.048), with no significant effect on systemic vascular resistance. Dapagliflozin reduced estimated stressed blood volume at rest and during peak exercise (ETD, -292 mm Hg [95% CI, -530 to -53] P=0.018), and improved venous capacitance evidenced by a decline in ratio of estimated stressed blood volume to total blood volume (ETD, -7.3% [95% CI, -13.3 to -1.3] P=0.020). Each of these effects of Dapagliflozin at peak exercise were also observed during matched 20W exercise intensity. Improvements in total arterial compliance and estimated stressed blood volume were correlated with decreases in body weight, and reduction in systolic BP with treatment was correlated with the change in estimated stressed blood volume during exercise (r=0.40, P=0.019). Decreases in BP were correlated with reduction in pulmonary capillary wedge pressure during exercise (r=0.56, P<0.001). In patients with HFpEF, treatment with Dapagliflozin improved systemic arterial compliance and venous capacitance during exercise, while reducing aortic characteristic impedance, suggesting a reduction in arterial wall stiffness. These vascular effects may partially explain the clinical benefits with sodium-glucose cotransporter-2 inhibitors in HFpEF. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04730947.

Aortic Calcification is Associated With the Difference Between Invasive Central and Cuff-Measured Brachial Blood Pressure in Chronic Kidney Disease.

Chronic kidney disease (CKD) is associated with accelerated vascular calcification and increased central systolic blood pressure when measured invasively (invCSBP) relative to cuff-based brachial systolic blood pressure (cuffSBP). The contribution of aortic wall calcification to this phenomenon has not been clarified. We, therefore, examined the effects of aortic calcification on cuffSBP and invCSBP in a cohort of patients representing all stages of CKD. During elective coronary angiography, invCSBP was measured in the ascending aorta with a fluid-filled catheter with simultaneous recording of cuffSBP using an oscillometric device. Furthermore, participants underwent a non-contrast computed tomography scan of the entire aorta with observer-blinded calcification scoring of the aortic wall ad modum Agatston. We included 168 patients (mean age 67.0 ± 10.5, 38 females) of whom 38 had normal kidney function, while 30, 40, 28, and 32 had CKD stages 3a, 3b, 4, and 5, respectively. Agatston scores adjusted for body surface area ranged from 48 to 40,165. We found that invCSBP increased 3.6 (95% confidence interval 1.4-5.7) mm Hg relative to cuffSBP for every 10,000-increment in aortic Agatston score. This association remained significant after adjustment for age, diabetes, antihypertensive treatment, smoking, eGFR, and BP level. No such association was found for diastolic BP. Patients with advanced aortic calcification have relatively higher invCSBP for the same cuffSBP as compared to patients with less calcification. Advanced aortic calcification in CKD may therefore result in hidden central hypertension despite apparently well-controlled cuffSBP. ClinicalTrials.gov identifier: NCT04114695.

Abstract 13299: Are There Differences in Left Ventricular and Aortic Pressures Measured With Fluid-Filled and Solid-State Pressure Catheters

Purpose: To compare left-ventricular and aortic pressures obtained using fluid-filled and high-fidelity solid-state pressure catheters in subjects undergoing left heart catheterization. Methods: Twenty subjects scheduled for a left heart catheterization were enrolled and 18 subjects completed this IRB-approved study. During catheterization, left-ventricular (LV) and aortic (AO) pressures were obtained using a fluid-filled pressure catheter (standard-of-care) and a high-fidelity solid-state pressure catheter synchronously. The pressure tracings were analyzed by two independent readers to measure LV systolic (LVSP), LV minimum diastolic (LVMDP), LV end diastolic (LVEDP), AO systolic (AOSP), and AO diastolic (AODP) pressures. Derivatives of the pressure waveforms were computed to estimate the isovolumic contraction and relaxation rates (peak ± dp/dt). The measurements were made over multiple cardiac cycles and averaged results were used for comparisons using repeated measures analysis of variance, post-hoc tests with Bonferroni corrections and Bland-Altman plots. Results: A significant main effect of the pressure catheter was noted for LVSP, LVMDP and AOSP (p &lt; 0.025). The LVSP and AOSP measured with fluid-filled pressure catheters were higher by 6.6 ± 6.9 mmHg and 4.6 ± 5.2 mmHg in comparison to the high-fidelity solid-state pressure catheter assessments. In contrast, the LVMDP measurements were 3.5 ± 5.7 mmHg lower than the solid-state pressure catheter measurements. When evaluating the differences between readers, the maximum difference was noted for LVEDP measurements (3.1 ± 2.4 mmHg; p ≤ 0.001). The differences in isovolumic contraction rate (66.4 ± 116.0 mmHg/s) and relaxation rate (60.5 ± 113.5 mmHg/s) were not significantly different between the two catheter systems after Bonferroni corrections for multiple comparisons (p &gt; 0.06). Bland-Altman analysis revealed a bias ranging from 0.8 to 6.6 mmHg for all the pressure measurements. Conclusions: There are differences in LVSP, LVMDP, and AOSP measured using fluid-filled and high-fidelity solid-state pressure catheters. Clinicians should be aware that the fluid-filled catheters commonly overestimate the true systolic pressures in the left ventricle and aorta.

Accuracy of Estimated Central Systolic Blood Pressure and Augmentation Index in Patients With Type 2 Diabetes Mellitus

It has been suggested that transfer functions to estimate central aortic systolic blood pressure (SBP) and central BP waveform parameters (i.e., augmentation index) may be less accurate in patients with type 2 diabetes mellitus (T2DM). However, these observations have not been confirmed in a large sample, which was the aim of this study. Consecutive patients with and without T2DM undergoing coronary angiography at the Royal Hobart Hospital had BP recorded at the ascending aorta and radial artery with a fluid-filled catheter. Radial BP waveforms were processed using the SphygmoCor Cardiovascular Management System (CVMS) transfer function (AtCor, Sydney) to estimate central BP. Two invasive waveform calibration methods were used: 1) aortic mean arterial pressure/diastolic BP (MAP/DBP); and 2) radial SBP and DBP (SBP/DBP). between-group analyses were performed unadjusted and adjusted for age, sex, hypertension, hypercholesterolaemia, body mass index, and coronary artery disease. Data from 64 patients with T2DM (61±11 years, 73% male) and 186 patients without T2DM (62±8 years, 70% male) were analysed. There was no difference in the accuracy of estimated central SBP between groups when compared with invasive aortic SBP from MAP/DBP calibration (T2DM –1.8±6 mmHg vs –1.1±5 mmHg; p=0.37; adjusted p=0.59) or radial SBP/DBP calibration (T2DM –1.2±9 mmHg vs –2.0±9 mmHg; p=0.57; adjusted p=0.66). Augmentation index was not significantly different between patients with and without T2DM 0.8±12% vs 3.7±14%; p=0.13, respectively). Estimated central SBP and augmentation index do not appear to be less accurate in patients with T2DM when waveforms are calibrated with invasive BP.

TOP2: Miniature Extravascular Aortic Sensor for Continuous Blood Pressure Measurement: In-vivo Validation Under Pathological Conditions

Purpose of the Study: In individuals suffering from cardiovascular diseases, and especially in heart failure patients supported with left ventricular assist devices (VADs), the long-term monitoring of arterial blood pressure (ABP) holds significant value for assessing the disease progression, monitoring patient compliance, and evaluating the treatment efficacy. Hence, it is imperative to advance and extensively validate new, accurate and robust sensory technologies for this purpose. Methods: The present study aimed to evaluate the performance of a newly developed hall-based magnetic aortic sensor (HBSD) in monitoring arterial blood pressure (ABP) in conditions of low pulse pressures that simulate the hemodynamic conditions of VAD supported patients (Magkoutas et al, JACC: Basic to Translational Science, 2023). To this end, twelve acute in-vivo experiments were performed using pigs that were connected to a cardiopulmonary bypass circuit, and their hemodynamic state was regulated through adjustments to the support rate and pharmacological stimulation. In each experiment, two HBSDs were implanted, one in the ascending and one in the descending aorta. The reference ABP measurements were obtained using an intravascular fluid-filled catheter. Results: The pressure signal provided by the HBSD accurately captured the highly varying pressure profiles, regardless of the pressure level, CPB support level, and effective pulse pressure. The analysis of the difference between the end-diastolic (EDP), systolic (SP), and mean arterial (MAP) pressure values measured with the HBSDs and the reference sensors (Figure 1B) demonstrates that the HBSDs provide highly accurate measurements with a mean absolute error less than 5 mm Hg, except for two cases. Furthermore, the comparison of the entire dataset of the HBSD and the reference sensor during one of the in-vivo experiments reveals a high linear association between the two methods, confirmed by an intraclass coefficient higher than 0.95 (Figure 1C). The results of the Bland-Altman plot in Figure 1D also indicate that the developed HBSD has a mean bias of 0 mmHg, with limits of agreement approximately equal to 8.5 mmHg, compared to the reference pressure sensor. Conclusion: This study provides evidence supporting the accuracy of the proposed HBSD in measuring the ABP waveform in pathological and varying hemodynamic conditions. This constitutes a crucial preliminary stage in advancing the HBSD towards clinical utilization, thereby unlocking the valuable information contained in the ABP waveform and enhancing patient surveillance and therapeutic intervention in individuals supported by VADs.Figure 1. A) Implantation procedure and components of the hall-based aortic sensor. B) Boxplots of the difference between the end-diastolic (EDP), systolic (SP), and mean arterial (MAP) pressure values measured with the HBSDs and the reference sensors. C) The intraclass coefficient (ICC) with 95% confidence intervals for the ABP measured with the HBSD and the reference ABP. D) Bland-Altman plot with the representation of the mean difference, the limits of agreement (LoA) (dashed line) from −1.96s to +1.96s, and 95% confidence intervals (CI).

KOROTKOFF SOUNDS DO NOT PROVIDE AN ACCURATE ESTIMATE OF SYSTOLIC AND DIASTOLIC PRESSURE IN SPHYGMOMANOMETRY AND CANNOT BE USED AS A CALIBRATION STANDARD FOR NIBP DEVICES

Objective: Noninvasive blood pressure (NIBP) devices are calibrated against validated auscultation sphygmomanometers using Korotkoff sounds. This study aimed to investigate the timing of Korotkoff sounds in relation to pulse appearance in the brachial artery and values of intra-arterial blood pressure. Design and method: Experiments were carried out on 15 participants, (14 males, 64.3 ±10.4 years; one female, 86 yo), undergoing coronary angiography. A conventional (oscillometric) BP cuff, with a microphone for Korotkoff sounds, was placed on the upper arm. Intra-arterial brachial artery pressure (IABP) was measured below the cuff with a fluid-filled catheter inserted via the radial artery and an external transducer. Finger photoplethysmography was used to measure brachial pulse wave velocity (PWV). Korotkoff sounds were processed electronically and custom algorithms identified the cuff pressure (CP) at which the first and last Korotkoff sounds were heard. PWV and max slope of the IABP pressure pulse were recorded to estimate arterial stiffness. Results: The brachial artery closed at a CP of 132.0±17.1 mmHg. Systolic (SBP), and diastolic (DBP) pressure were 147.6±14.3 and 72.7±10.1mmHg; mean pressure (MP, 100.1±10.4 mmHg) was similar to MP derived from the peak of the oscillogram (98.5±13.6 mmHg). Difference between IABP and CP recorded at first and last occurrence of Korotkoff sounds were, SBP: 18.9±8.3 (range 2-29) mmHg, DBP: 4.0±4.3 (range -1.6 -12.4) mmHg. Multiple linear regression showed that differences increase with arterial stiffness and can be compensated for using a prediction equation for calculation of true SBP (tSBP) using heart rate (HR) and Korotkoff derived systolic (SBPk) and diastolic (DBPk), at least over the limited age range for this study cohort. Conclusions: SBP and DBP derived from the onset and termination of Korotkoff sounds can underestimate IABP by up to 29 mmHg. Since Korotkoff sounds are the recommended method mandated by the universal standard for the validation of blood pressure measuring devices, these errors are propagated through to all NIBP measurement devices irrespective of whether they use auscultatory or oscillometric methods thus explaining the well known differences recorded between NIBP measurements and intra-arterial BP measurements.

CAN RECORDING KOROTKOFF SOUNDS DURING BRACHIAL CUFF INFLATION PROVIDE MORE ACCURATE NON-INVASIVE ESTIMATES OF INTRA-ARTERIAL BLOOD PRESSURE?

Objective: We have previously demonstrated that recording onset and termination of Korotkoff sounds as markers of systolic (SBP) and diastolic (DBP) during brachial cuff deflation results in underestimation of true SBP. In this study we explore whether recording Korotkoff sounds during cuff inflation provides more accurate non-invasive estimates of intra-arterial blood pressure (IABP). Design and method: Experiments were carried out on 15 participants, (14 males, 64.3 ± 10.4 years; one female, 86 yo), undergoing coronary angiography. A conventional (oscillometric) BP cuff, with a microphone for Korotkoff sounds, was placed on the upper arm. The cuff was inflated at rate of approximately 2.5mm Hg/sec and deflated at the same rate. Inflation and deflation cycles were randomised and separated by 2 - 3 minutes. IABP was measured below the cuff with a fluid-filled catheter inserted via the radial artery and an external transducer. Korotkoff sounds were processed electronically, and custom algorithms identified the cuff pressure (CP) at which the first and last Korotkoff sounds were heard. Results: Systolic (SBP), and diastolic (DBP) pressure were 147.7.6 ± 12.7 and 70.7 ± 9.7mmHg. The CP at which the brachial artery closes during rapid (∼20mmHg/sec) cuff inflation (132.0 ± 17.1) was similar to that of slow (2.5mmHg/sec) inflation (132.0 ± 16.3 mmHg). However, peak Korotkoff sound energy was significantly reduced (P = 0.003) from 0.19 ± 0.1 to 0.15 ± 0.09 RMS volts and the Korotkoff sounds were often observed to disappear prematurely before brachial artery closure. Difference between intra-arterial SBP and CP at the last recorded Korotkoff sound (27.5 ± 9.3 mmHg) during cuff inflation was significantly higher (P = 0.0025) than during slow cuff deflation (18.9 ± 8.3 mmHg). In contrast, DBP recorded at first onset of the Korotkoff sounds (70.5 ± 11.1 mmHg) was consistently similar to intra-arterial DBP (70.7 ± 9.7 mmHg). Conclusions: SBP estimates derived from the last Korotkoff sound recorded as the cuff inflates generates greater errors than when Korotkoff sounds are first recorded as the cuff deflates. In contrast, the estimate of DBP derived from the first onset of the Korotkoff sound as the cuff inflates, appears to reflect accurately the true intra-arterial DBP.

Discussion on the zero-calibration and the zero line in the measurement of central venous pressure and invasive arterial blood pressure

To figure out the timing of zeroing and the location of the zero line in the central venous pressure (CVP) monitoring and invasive arterial blood pressure (IBP) monitoring, and to provide scientific and accurate data for patients management. The liquid vessel models were used to simulate the pressure measurement process of the continuous pressure monitoring system. Based on the theory of fluid mechanics and the knowledge of blood pressure physiology and cardiovascular anatomy, the composition and influencing factors of the pressure in the fluid-filled catheter system during the zeroing and placing the transducer in the zero line of CVP and IBP, were analyzed. The pressure in the liquid-filled catheter system was composed of atmospheric pressure, the pressure of pumping bag, the gravity of the water column (the vertical distance between the liquid level of Murphy's dropper and pressure transducer, ΔH), and the resistance of tube wall. This pressure value is set as a pressure of 0 mmHg (1 mmHg ≈ 0.133 kPa). In the process of pressure measurement, when the pressure transducer was placed at a horizontal position of 10 cm below the highest liquid level of the vessel, the pressure measured at different catheter tip positions was all 10 cmH2O (1 cmH2O ≈ 0.098 kPa); When the pressure transducer was placed at the horizontal position of the highest liquid level of the vessel, the measured pressure is 0 mmHg. Zeroing should repeatedly be performed only when one or more conditions (atmospheric pressure, pressure of pumping bag, gravity of ΔH water column and resistance of tube wall) are changed. In the measurement process, the pressure transducer should be placed at the zero line position at any time to eliminate the influence of hydrostatic pressure and to ensure the objective and accurate value.

CLINICAL AND DEMOGRAPHIC FEATURES ASSOCIATED WITH ELEVATED LEFT VENTRICULAR END-DIASTOLIC PRESSURE IN PATIENTS UNDERGOING PRIMARY PERCUTANEOUS CORONARY INTERVENTION

Objectives: Prognostic importance of left ventricular end-diastolic pressure (LVEDP) is well established, hence, it is important to understand the factors associated with increased LVEDP for individualized risk stratification of ST-segment elevation myocardial infarction (STEMI) patients. There is dearth of data regarding clinical associates of elevated LVEDP, therefore, the purpose of current study was to evaluate the clinical indicators and phenotype of elevated LVEDP in STEMI patients undergoing primary percutaneous coronary intervention (PCI).&#x0D; Methodology: This descriptive observational study included patients diagnosed with STEMI and undergone primary PCI. LVEDP was measured using a fluid-filled pig-tail catheter before reperfusion but after angiography. Elevated LVEDP was taking as &gt;25 mmHg.&#x0D; Results: A total of 498 patients were included, 23.7% (118) were female patients and mean age was 53.7 ± 11.7 years. Distribution of LVEDP was ≤15 mmHg in 48% (239), 15-25 mmHg in 42% (209), and &gt;25 mmHg in remaining 10% (50) of the patients. Elevated LVEDP was found to be associated with increased heart rate (HR) with adjusted odds ratio of 1.05 [1.02-1.08], decreased systolic blood pressure (SBP) (0.95 [0.9-0.99]), Killip class II or high (9.36 [3.38-25.9]), and hypertension (4.63 [1.55-13.82]).&#x0D; Conclusion: Hemodynamic instability at presentation such as elevated HR, reduced SBP, higher Killip class and hypertension are the key indicators of elevated LVEDP.

LACK OF PULMONARY HYPERTENSION REGRESSION IN PATIENTS WITH SEVERE AORTIC STENOSIS ASSOCIATED WITH CHRONIC LUNG DISEASE AFTER TRANSCATHETER AORTIC VALVE REPLACEMENT

LACK OF PULMONARY HYPERTENSION REGRESSION IN PATIENTS WITH SEVERE AORTIC STENOSIS ASSOCIATED WITH CHRONIC LUNG DISEASE AFTER TRANSCATHETER AORTIC VALVE REPLACEMENT

Use of a Pressure Wire for Automatically Correcting Artifacts in Phasic Pressure Tracings From a Fluid-Filled Catheter

Background/purposeMatching phasic pressure tracings between a fluid-filled catheter and high-fidelity pressure wire has received limited attention, although each part contributes half of the information to clinical decisions. We aimed to study the impact of a novel and automated method for improving the phasic calibration of a fluid-filled catheter by accounting for its oscillatory behavior. Methods/materialsRetrospective analysis of drift check tracings was performed using our algorithm that corrects for mean difference (offset), temporal delays (timing), differential sensitivity of the manifold transducer and pressure wire sensor (gain), and the oscillatory behavior of the fluid-filled catheter described by its resonant frequency and damping factor (how quickly oscillations disappear after a change in pressure). ResultsAmong 2886 cases, correcting for oscillations showed a large improvement in 28 % and a medium improvement in 41 % (decrease in root mean square error >0.5 mmHg to <1 or 1-2 mmHg, respectively). 96 % of oscillators were underdamped with median damping factor 0.27 and frequency 10.6 Hz. Fractional flow reserve or baseline Pd/Pa demonstrated no clinically important bias when ignoring oscillations. However, uncorrected subcycle non-hyperemic pressure ratios (NHPR) displayed both bias and scatter. ConclusionsBy automatically accounting for the oscillatory behavior of a fluid-filled catheter system, phasic matching against a high-fidelity pressure wire can be improved compared to standard equalization methods. The majority of tracings contain artifacts, mainly due to underdamped oscillations, and neglecting them leads to biased estimates of equalization parameters. No clinically important bias exists for whole-cycle metrics, in contrast to significant effects on subcycle NHPR.

AORTIC CALCIFICATION INCREASES CENTRAL BLOOD PRESSURE RELATIVE TO BRACHIAL BLOOD PRESSURE IN CKD PATIENTS – A STUDY IN PATIENTS UNDERGOING ELECTIVE CORONARY ANGIOGRAPHY

Objective: Chronic kidney disease (CKD) and arterial stiffness are associated with increased central (aortic) systolic blood pressure (cSBP) relative to brachial systolic blood pressure (bSBP). This study examined the impact of aortic calcification on cSBP relative to bSBP in patients with CKD. Design and method: Patients with or without CKD undergoing elective coronary angiography (CAG) at Aarhus University Hospital were considered for inclusion in this cross-sectional study. During CAG, cSBP was measured in the ascending aorta with a fluid-filled catheter while bSBP was measured simultaneously with an oscillometric device using a cuff. Furthermore, patients underwent a non-contrast computed tomography (CT) scan of the entire aorta with subsequent blinded Agatston-scoring of the aorta from (but excluding) the aortic valve to the aortic bifurcation. Carotid-femoral pulse wave velocity was measured in duplicate using a Sphygmocor device. Data are presented as mean ± standard deviation unless stated otherwise. Statistical comparisons were made using Wilcoxon rank sum test for differences between 2 groups and Bonferroni-adjusted Kruskal-Wallis test when testing for differences between &gt; 2 groups. Results: 149 patients were included in the study. Of these, 134 patients had a CT-scan of sufficient quality to allow analysis. Patient characteristics and measurements of BP and pulse wave velocity are presented in Table 1. Agatston-score was higher in CKD patients as compared to patients with normal kidney function (table 1, P &lt; 0.001). bSBP was 6.5 ± 13.1 mmHg higher than cSBP in patients categorized into the first tertile of Agatston-scores. This difference was reduced to 3.3 ± 11.0 mmHg in the second tertile (p = 0.31, compared to first tertile) and -2.6 ± 16.8 mmHg in the third tertile (p &lt; 0.01, compared to first tertile). Conclusions: Patients with CKD have a higher degree of aortic calcification. Furthermore, patients with a high degree of aortic calcification have a higher invasively measured cSBP as compared to the bSBP measured with an ordinary oscillometric BP device.

High-rate atrial pacing to reduce left-sided filling pressures: a combined computational and clinical pilot study

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): This work was supported by the Netherlands Organisation for Scientific Research (NWO- ZonMw, VIDI grant 016.176.340 to J.L.) and the Dutch Heart Foundation (ERA-CVD JTC2018 grant 2018T094; Dr. Dekker Program grant 2015T082 to J.L.) Background In heart failure patients, interventions to reduce elevated left ventricular (LV) filling pressure improve symptoms and reduce the risk of hospitalization. In this combined computational-clinical study, we explore high-rate atrial pacing as an alternative intervention to reduce LV filling pressure. Methods First, the theoretical basis was explored in a computational model of reduced LV compliance and various fixed atrioventricular delays. Second, an explorative clinical study was conducted in 19 paroxysmal atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) with sinus rhythm at the beginning of the procedure. Prior to the PVI, atrial pacing rate was gradually increased from resting heart rate to Wenckebach point with 10bpm increments. LA pressure was continuously monitored with a fluid-filled transseptal catheter. Results Computational modelling demonstrated a parabolic relationship between atrial pacing rate and LA pressure depending on atrioventricular delay (Figure A). In patients (Figure B), intermediately increased rates (60bpm[60-70], median[IQR], to 90bpm[73-100], respectively) reduced LA pressure from 16.0mmHg[14.0-20.5] to 14.0mmHg[10.8-16.8]. Highly increased rates (130bpm[120-140]) significantly increased LA pressure to 26.0mmHg[21.5-27.8]. Conclusions Both the model simulations and the subsequent clinical pilot study support the hypothesis that high-rate atrial pacing can reduce left-sided filling pressure. However, inter-patient variability of response to high-rate pacing was observed, to which simulations identified atrioventricular conduction to be a potential source.

New Method to Estimate Central Systolic Blood Pressure From Peripheral Pressure: A Proof of Concept and Validation Study.

Objective: The non-invasive estimation of central systolic blood pressure (cSBP) is increasingly performed using new devices based on various pulse acquisition techniques and mathematical analyses. These devices are most often calibrated assuming that mean (MBP) and diastolic (DBP) BP are essentially unchanged when pressure wave travels from aorta to peripheral artery, an assumption which is evidence-based. We tested a new empirical formula for the direct central blood pressure estimation of cSBP using MBP and DBP only (DCBP = MBP2/DBP).Methods and Results: First, we performed a post-hoc analysis of our prospective invasive high-fidelity aortic pressure database (n = 139, age 49 ± 12 years, 78% men). The cSBP was 146.0 ± 31.1 mmHg. The error between aortic DCBP and cSBP was −0.9 ± 7.4 mmHg, and there was no bias across the cSBP range (82.5–204.0 mmHg). Second, we analyzed 64 patients from two studies of the literature in whom invasive high-fidelity pressures were simultaneously obtained in the aorta and brachial artery. The weighed mean error between brachial DCBP and cSBP was 1.1 mmHg. Finally, 30 intensive care unit patients equipped with fluid-filled catheter in the radial artery were prospectively studied. The cSBP (115.7 ± 18.2 mmHg) was estimated by carotid tonometry. The error between radial DCBP and cSBP was −0.4 ± 5.8 mmHg, and there was no bias across the range.Conclusion: Our study shows that cSBP could be reliably estimated from MBP and DBP only, provided BP measurement errors are minimized. DCBP may have implications for assessing cardiovascular risk associated with cSBP on large BP databases, a point that deserves further studies.

Real-time CMR guidance for intracardiac and great vessel pressure mapping in patients with congenital heart disease using an MR conditional guidewire-results of 25 patients.

The aim of this study was to test a CE-certified MR-conditional guidewire to facilitate blood pressure measurement in cardiovascular magnetic resonance (CMR) using fluid-filled catheters in patients with congenital heart disease (CHD). The main purpose was to determine procedural success in a post market clinical follow-up (PMCF) for routine procedure in a diagnostic and interventional workflow. Real-time CMR provides high quality imaging without the risk of exposing the patient to X-rays, especially for patients with irregular heart anatomy and patients who are susceptible to radiation and iodinated contrast media. To date, the assessment of blood pressure gradients is not a common feature of CMR, as these gradients cannot be accurately evaluated in routine CMR. Twenty-five CHD patients who were planned for combined clinical CMR and diagnostic and/or interventional catheterization were enrolled in the trial. Prior to inclusion, a specific procedure for catheterization in CMR was defined, encompassing the assessment of pressure and pressure gradients in the heart and great vessels. By the use of an MR-conditional guidewire we successfully measured specific pressure and pressure gradients in up to 92% of cases with liquid-filled catheters which were guided exclusively under CMR guidance. There were no guidewire-related adverse events, and guidewire guidance and manipulation of catheters were successful. Using a MR-conditional guidewire assists in easily reaching targets in the heart and great vessels and makes the catheter itself visible, so that invasive blood pressure assessment by CMR guidance with liquid-filled catheters can be improved. Cardiovascular magnetic resonance (CMR); congenital heart disease (CHD); cardiac catheterization; magnetic resonance; pressure; guidewire.

Abstract 9538: Comparison of Central Aortic Pressures Obtained Using an Invasive Pressure Catheter and the Noninvasive Sphygmocor Device

Introduction: The SphygmoCor (ATCOR, Naperville, IL) device utilizes a generalized transfer function based on patient’s age and gender to derive the aortic pressure pulse from the brachial-cuff based pressure measurements. This study compared aortic pressures obtained using SphygmoCor with aortic pressures obtained during cardiac catheterization. Hypothesis: Mean differences in aortic pressures obtained using SphygmoCor and pressure catheters will be less than 5 mmHg. Methods: After IRB approval, 136 patients were enrolled. During standard-of-care catheterization procedure, aortic pressure measurements were obtained using fluid-filled catheters. In a subset of patients (n = 13) the aortic pressure values were also obtained using solid-state high-fidelity Millar catheters. Immediately after the catheterization procedure, while the patients were still in the catheterization laboratory (on the procedure table), central aortic pressures were estimated with the SphygmoCor device. The measured and estimated aortic pressures were compared using linear regression and Bland-Altman analysis. A linear fit was performed to derive an additional transfer function to convert SphygmoCor pressure values to catheter-based aortic pressures, and the resulting differences in pressure values were compared. A bootstrap analysis was performed to test the generalizability of this transfer function. Results: Mean differences in systolic, diastolic and pulse aortic pressures obtained using the two techniques ranged from 6.5 to 18.0 mmHg (p &lt; 0.001). In the subset with high-fidelity catheters, the differences ranged from 8.0 to 18.9 mmHg. With the linear-fit transfer function, the differences in systolic, diastolic and pulse aortic pressures were low (&lt; 1 mmHg) corresponding to a reduction in bias noted with Bland-Altman analysis. The bootstrap analysis of the transfer function (100 iterations) achieved a coefficient of variation for the root mean square error &lt; 8.4% for systolic, diastolic and pulse aortic pressures. Conclusions: The magnitude of the differences between the SphygmoCor-estimated and catheter-based systolic, diastolic and pulse aortic pressures reduced considerably after using the linear-fit transfer function derived in this study.

Derivation of in vivo pressure-volume loops for post-heart transplant patients using real-time 3D echocardiography and left ventricular catheterisation

Abstract Background Image-based methods that combine catheterisation with non-concurrent cardiac magnetic resonance (CMR) imaging data and echocardiography (echo) is gaining more interest than the conductance catheter method to derive pressure-volume loops (PVLs) due to improved accuracy and accessibility of LV volume quantification [1–3]. However, accurate temporal registration between LV pressure and volume is not well developed. Purpose We propose a framework for temporally registering invasive LV and aortic pressures (LVP and AOP) acquired during left heart catheterisation with real time 3D echocardiography (RT3DE) to generate in vivo PVLs in a group of heart transplant (HTx) recipients. Methods 25 orthotopic HTx recipients (mean age: 54±8 years and 7 female) indicated for routine coronary assessment were recruited for invasive hemodynamic measurement and RT3DE imaging. A fluid-filled pigtail catheter was used to measure LVP and AOP with simultaneous electrocardiogram (ECG) over several (9–15) heartbeats. Within an hour of catheterisation, single-beat transthoracic RT3DE of the LV was performed from the apical window in a left lateral decubitus position. Imaging parameters were optimized for each patient to maximize the temporal resolution (between 15–41 imaging frames per cycle). We developed a piecewise linear temporal scaling method based on cardiac events (end-diastole (ED), end of isovolumic contraction (eIVC), end-systole (ES), end of isovolumic relaxation (eIVR), and diastasis (DS)) of RT3DE and haemodynamic measurement to resample the LVP at the RT3DE imaging frames between the cardiac events to construct PVLs (Fig. 1a). Geometric LV models were manually fitted at ED and ES, followed by automatic tracking across intermediary frames to estimate LV volume over the entire cardiac cycle (Fig. 1b). The temporally aligned pressure values were further averaged to find the beat-averaged LV PVL (Fig. 1c). Results Based on the number of cardiac cycles selected for haemodynamic analysis, multiple in vivo PVLs were constructed for each patient. A beat-averaged PVL was also computed for each patient (Fig.1d). With the exception of one case, the beat-averaged PVLs exhibited classically representative shape with distinct isovolumic contraction and isovolumic relaxation phases. The individual diastolic PVRs for all patients are shown in Fig.1e, with beat-to-beat variation observed in most patients. For some cases, the variation manifested as an offset in LVP, whereas changes in the diastolic PVR slope were observed in other cases. Conclusion Temporal alignment scheme based on cardiac events allowed accurate derivation of patient-specific in vivo PVLs from catheterization and RT3DE measurements. Application to heart transplant recipients revealed beat-to-beat variation of haemodynamic state. Further analysis of the diastolic PVRs will allow quantification of chamber stiffness for HTx recipients. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Health Research Council of New Zealand Patient-specific PVLs

Comparison Between Two Pharmacologic Strategies to Alleviate Rewarming Shock: Vasodilation vs. Inodilation.

Rewarming from hypothermia is often challenged by coexisting cardiac dysfunction, depressed organ blood flow (OBF), and increased systemic vascular resistance. Previous research shows cardiovascular inotropic support and vasodilation during rewarming to elevate cardiac output (CO). The present study aims to compare the effects of inodilatation by levosimendan (LS) and vasodilation by nitroprusside (SNP) on OBF and global oxygen transport during rewarming from hypothermia. We used an in vivo experimental rat model of 4 h 15°C hypothermia and rewarming. A stable isotope-labeled microsphere technique was used to determine OBF. Cardiac and arterial pressures were monitored with fluid-filled pressure catheters, and CO was measured by thermodilution. Two groups were treated with either LS (n = 7) or SNP (n = 7) during the last hour of hypothermia and throughout rewarming. Two groups served as hypothermic (n = 7) and normothermic (n = 6) controls. All hypothermia groups had significantly reduced CO, oxygen delivery, and OBF after rewarming compared to their baseline values. After rewarming, LS had elevated CO significantly more than SNP (66.57 ± 5.6/+30% vs. 54.48 ± 5.2/+14%) compared to the control group (47.22 ± 3.9), but their ability to cause elevation of brain blood flow (BBF) was the same (0.554 ± 0.180/+81 vs. 0.535 ± 0.208/+75%) compared to the control group (0.305 ± 0.101). We interpret the vasodilator properties of LS and SNP to be the primary source to increase organ blood flow, superior to the increase in CO.