Fick Cardiac Output Research Articles

Echocardiographic Predictors of Hemodynamics in Patients Supported With Left Ventricular Assist Devices

The assessment of hemodynamics in patients supported with left ventricular assist devices (LVADs) is often challenging. Physical examination maneuvers correlate poorly with true hemodynamics. We assessed the value of novel transthoracic echocardiography (TTE)-derived variables to reliably predict hemodynamics in patients supported with LVAD. A total of 102 Doppler-TTE images of the LVAD outflow cannula were obtained during simultaneous invasive right heart catheterization (RHC) in 30 patients supported with continuous-flow LVADs (22 HMII, 8 HVAD) either during routine RHC or during invasive ramp testing. Properties of the Doppler signal though the outflow cannula were measured at each ramp stage (RS), including the systolic slope (SS), diastolic slope (DS), and velocity time integral (VTI). Hemodynamic variables were concurrently recorded, including Doppler opening pressure (MAP), heart rate (HR), right atrial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure (PCWP), Fick cardiac output (CO) and systemic vascular resistance (SVR). Univariate and multivariate regression analyses were used to explore the dependence of PCWP, CO, and SVR on DS, SS, VTI, MAP, HR, and RS. Multivariate linear regression analysis revealed significant contributions of DS on PCWP (PCWPpred = 0.164DS + 4.959; R = 0.68). Receiver operating characteristic (ROC) curve analysis revealed that PCWPpred could predict an elevated PCWP ≥18 mm Hg with a sensitivity (Sn) of 94% and specificity (Sp) of 85% (area under the ROC curve 0.88). CO could be predicted by RS, VTI, and HR (COpred = 0.017VTI + 0.016HR + 0.12RS + 2.042; R = 0.61). COpred could predict CO ≤4.5 L/min with Sn 73% and Sp 79% (AUC 0.81). SVR could be predicted by MAP, VTI, and HR (SVRpred = 15.44MAP - 5.453VTI - 6.349HR + 856.15; R = 0.84) with Sn 84% and Sp 79% (AUC 0.91) to predict SVR ≥1200 dyn-s/cm5. Doppler-TTE variables derived from the LVAD outflow cannula can reliably predict PCWP, CO, and SVR in patients supported with LVADs and may mitigate the need for invasive testing.

Post-Exercise Oxygen Uptake Recovery Delay: A Novel Index of Impaired Cardiac Reserve Capacity in Heart Failure

ObjectivesThis study sought to characterize the functional and prognostic significance of oxygen uptake (VO2) kinetics following peak exercise in individuals with heart failure (HF). BackgroundIt is unknown to what extent patterns of VO2 recovery following exercise reflect circulatory response during exercise in HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). MethodsWe investigated patients (30 HFpEF, 20 HFrEF, and 22 control subjects) who underwent cardiopulmonary exercise testing with invasive hemodynamic monitoring and a second distinct HF cohort (n = 106) who underwent noninvasive cardiopulmonary exercise testing with assessment of long-term outcomes. Fick cardiac output (CO) and cardiac filling pressures were measured at rest and throughout exercise in the initial cohort. A novel metric, VO2 recovery delay (VO2RD), defined as time until post-exercise VO2 falls permanently below peak VO2, was measured to characterize VO2 recovery kinetics. ResultsVO2RD in patients with HFpEF (median 25 s [interquartile range (IQR): 9 to 39 s]) and HFrEF (28 s [IQR: 2 to 52 s]) was in excess of control subjects (5 s [IQR: 0 to 7 s]; p < 0.0001 and p = 0.003, respectively). VO2RD was inversely related to cardiac output augmentation during exercise in HFpEF (ρ = −0.70) and HFrEF (ρ = −0.73, both p < 0.001). In the second cohort, VO2RD predicted transplant-free survival in univariate and multivariable Cox regression analysis (Cox hazard ratios: 1.49 and 1.37 per 10-s increase in VO2RD, respectively; both p < 0.005). ConclusionsPost-exercise VO2RD is an easily recognizable, noninvasively derived pattern that signals impaired cardiac output augmentation during exercise and predicts outcomes in HF. The presence and duration of VO2RD may complement established exercise measurements for assessment of cardiac reserve capacity.

Comparison of thermodilution and indirect Fick cardiac outputs in pulmonary hypertension

BackgroundThe accurate measurement of cardiac output (CO) is required in patients with pulmonary hypertension (PH).While both the thermodilution (TDCO) and indirect Fick (IFCO) methods are commonly used, there is little data comparing them in patients with PH. MethodsWe performed a retrospective analysis of patients evaluated at our center. All patients who had right heart catheterization (RHC) within 3 months of an echocardiogram, and CO assessment by both TDCO and IFCO methods were included. Bland-Altman analysis was used to assess agreement between the two methods. We further evaluated their agreement in each sex, and within tertiles of age, BMI and TR severity. We investigated the correlation between each method of CO and objective parameters of right ventricular function on echocardiography. ResultsIn a cohort of 168 patients, the correlation between IFCO and TDCO was modest at (r = 0.61). On average, values for CO were lower with IFCO than with TDCO, by 0.62 L/min (95% CI −0.82, −0.40). This difference was greater for females: 0.86 L/min (95% CI −1.08, −0.63) and in the highest tertile of BMI: 0.97 L/min (95% CI −1.4, −0.55). Moderate and severe TR did not in general result in lower TDCO values. Echocardiographic parameters of right ventricular function were correlated more strongly with TDCO than with IFCO. ConclusionIn PH patients, IFCO was substantially lower than TDCO on average, suggesting that these two techniques cannot be used interchangeably. TDCO correlated more strongly with echocardiographic measures of RV function, suggesting that it may be preferred over IFCO.

Validation of Peripherally Inserted Central Catheter-Derived Fick Cardiac Outputs in Patients with Heart Failure

The pulmonary artery catheter (PAC) remains the gold standard to calculate Fick cardiac outputs (FCOs) in patients with heart failure admitted to the intensive care unit (ICU). The peripherally inserted central catheter (PICC) provides long-term intravenous access and is used outside the ICU; however, there is scant literature validating venous oxygen saturations (VOSs) from PICC lines. Heart failure patients in the ICU with an existing PAC requiring a PICC line to transition were enrolled. Three blood samples were taken per person (1 at PICC, 1 at central venous pressure [CVP], and 1 at distal PAC). We performed repeated measures analysis of variance, as well as reliability analysis on 31 subjects (77% male, 71% Caucasian, mean ± standard deviation age 60 ± 8 years, 80% on inotropes). The average VOSs were 62 ± 11%, 62 ± 12%, and 61 ± 9% for the PICC line, CVP, and distal port, respectively (p = 0.66); there was excellent reliability (0.79). The median FCOs were 5 [4, 6], 5 [4, 6], and 5 [4, 6] L/min at the PICC, CVP, and distal port, respectively (p = 0.91); there was fair-to-good reliability (0.67). In conclusion, VOS and FCO did not differ by location, on average. Reliable data may be obtained through the PICC line, after evaluation from the PAC. The PICC may provide longer-term hemodynamic assessment while improving patient comfort.

Sildenafil for This Heart Failure With a Preserved Ejection Fraction? Diastolic Dysfunction and Gerbode Defect Induced Combined Precapillary and Postcapillary Pulmonary Hypertension

SESSION TITLE: Pulmonary Vascular Disease SESSION TYPE: Affiliate Case Report Slide PRESENTED ON: Tuesday, October 31, 2017 at 04:30 PM - 05:30 PM INTRODUCTION: A Gerbode defect is a ventricular septal defect (VSD) communicating directly between the left ventricle (LV) and right atrium (RA). The shunt can be either congenital or acquired. Acquired cases are secondary to cardiothoracic surgeries. CASE PRESENTATION: A 66 year-old woman was hospitalized with acute on chronic diastolic heart failure. She had a history of mitral valve papillary muscle rupture replaced with a bioprosthesis and bypass for coronary artery disease. BP was 99/69 (MAP 70), HR 70 bpm, with normoxia at rest and with exertion. Exam showed an internal jugular vein with prominent v-wave, loud holosystolic murmur, right sided heave and 3+ edema. Lab results showed a hemoglobin of 17 mg/dL, creatinine 1.6 mg/dL and BNP 2584 pg/mL. Surface echocardiogram revealed preserved LV function, markedly dilated right ventricle with flattening of the intraventricular septum, severe tricuspid regurgitation (TR), tricuspid annular plane systolic excursion of 1.6 cm, TR peak velocity jet of 3.3 m/sec and a negative bubble study. A transesophageal echocardiogram showed a large left to right communication in the posterior area of the atria with a high velocity systolic flow. Several right heart catherizations showed persistent oxygen step up at the level of the right atrium. DISCUSSION: The presence of the shunt complicated hemodynamic interpretation. This elevated the pulmonary artery saturation falsely increasing the estimated Fick cardiac output (CO). The low CO by thermodilution and renal insufficiency were consistent with a hemodynamic shock state, and improved with furosemide, sildenafil and midodrine. LV-RA shunt correction was not possible in this patient due to severe RV dysfunction and high peri-operative risk. CONCLUSIONS: Gerbode defect is a VSD communicating directly between the LV and RA. Sildenafil has been shown to reduce pulmonary pressures and improve hemodynamics in patients with combined PH. Longstanding hydrostatic pressure within the pulmonary capillaries with persistent high flow produced venulae damage and vascular remodeling similar to other causes of pulmonary artery hypertension. We describe a patient with combined pre and post-capillary PH with progressive right heart failure successfully treated with medical therapy. Reference #1: Opitz CF, Hoeper MM, Gibbs SR, et al. Pre-capillary, combined, and post-capillary pulmonary hypertension: a pathophysiological continuum. J Am Coll Cardiol 2016 Reference #2: Yuan Shi-Min. A systematic review of acquired left ventricle to right atrium shunt. Hellenic J Cardiol 2015 DISCLOSURE: The following authors have nothing to disclose: Domingo Franco-Palacios, Patrick Kicker, Oksana Shlobin, Qiong Zhao, Mardi Gomberg-Maitland No Product/Research Disclosure Information

165 - The Peripherally Inserted Central Catheter is a Reliable Tool to Obtain Venous Oxygen Saturation in Patients with Heart Failure

Background: For heart failure (HF) patients in the intensive care unit (ICU), venous oxygen saturations, which are used to calculate Fick cardiac output, are routinely measured from the distal port of the pulmonary artery catheter (PAC), which is typically in place to deliver inotropes. However, the PAC is not meant for long-term use and many patients require inotropes outside the ICU. The peripherally inserted central catheter (PICC) offers increased mobility, is intended for long-term use, and is used to deliver inotropes to patients outside of the ICU; yet, venous oxygen saturations are not currently measured via the PICC line. Objective: To determine if patients' oxygen saturation values differ between the PICC line and the distal Pulmonary artery (PA) and the proximal central venous pressure (CVP) ports on the PAC line. Methods: HF patients in the ICU were prospectively enrolled at the Baylor University Medical Center, Dallas, Texas. A total of 3 blood samples were taken per person (one sample at each PICC, CVP, and distal location). We performed repeated measures analysis of variance, as well as correlation and reliability analyses to assess the venous oxygen saturations. Results: There were 31 subjects included in the analysis; 77.4% were male, 71.0% were Caucasian, their mean (±standard deviation) age was 60.2 ± 8.46 years, and 80.0% received inotropes. The average oxygen saturation was 62.3 ± 10.7, 62.4 ± 11.7, and 61.4 ± 9.3 for the PICC line, CVP port, and distal port, respectively (PHuynh-Feldt = 0.66). The values from the PICC line had a strong, positive, linear correlation with those from the CVP and distal ports (r = 0.89, 0.76, respectively). Similarly, the correlation between the CVP and distal port was 0.72. The reliability of the values obtained across the 3 locations was excellent (Shrout-Fleiss reliability = 0.79). Conclusions: The venous oxygen saturation did not differ significantly between the PICC line, CVP port, or distal port, on average. Further, the majority (61.3%) of the patients' saturations differed by 5 or less percentage points between the PICC line and distal port of the PAC. This work indicates that reliable values of venous oxygen saturation may be obtained via the PICC line, after initial evaluation from the PAC. In turn, this may provide long-term hemodynamic assessment out of the ICU while improving patient comfort and mobility

Cardiac Output Assessment in Patients Supported with Left Ventricular Assist Device: Discordance Between Thermodilution and Indirect Fick Cardiac Output Measurements.

Cardiac output (CO) assessed by thermodilution (TD) and indirect Fick (iFK) methods is commonly employed in left ventricular assist device (LVAD) patients; however, no study has assessed agreement. This study assesses correlation between these methods and association with hemodynamic/echocardiographic data in LVAD patients. Discordance was defined as a 20% difference between TD and iFK CO measurements. Bias and agreement were determined via the Bland-Altman technique in both the overall sample and iFK-stratified tertiles. Correlation with each assessment of CO and right heart catheterization (RHC) hemodynamics was performed. Among 111 RHCs, the mean CO for TD and iFK were 4.65 ± 1.33 (range: 1.44-9.30) and 5.37 ± 1.51 (range: 3.07-11.80) L/min (p < 0.001), respectively, with a calculated discordance of 45.9%. A correlation coefficient of 0.66 with a bias of -0.72 L/min was found. The lower and upper limit of precision were -3.12 and 1.68 L/min, respectively. By tertile analysis, bias (lower and upper limit of precision) for the low, middle, and high tertile groups were -0.24 (-1.88 and 1.40), -0.48 (-2.50 and 1.53), and -1.39 (-4.18 and 1.39) L/min, respectively. No significant correlation was found between either method with right atrial pressure or pulmonary capillary wedge pressure or any valvular condition. Substantial discrepancies exist between TD and iFK CO in LVAD patients. Although fixed bias was small, the limits of agreement extend into the clinically relevant area, with larger bias being present at higher CO. Studies with flow probes are needed to define which method better represents CO in LVAD patients.

Non-invasive cardiac output monitor validation study in pediatric cardiac surgery patients

Study objectiveTo validate a non-invasive cardiac output monitor in pediatric cardiac surgery patients. DesignProspective trial. SettingOperating room. Patients20 pediatric cardiac surgery patients ASA physical status 3 and 4. InterventionsAesculon noninvasive cardiac output monitor was used and compared to the cardiac output derived from the Fick equation. Oxygen consumption was measured and blood samples were taken from the arterial line and from the superior and inferior vena cava. MeasurementsNoninvasive cardiac output and cardiac index and Fick cardiac output and cardiac index. Oxygen consumption was measured by the TreyMed metabolic monitor. Blood samples were simultaneously drawn from the arterial line and from the superior and inferior vena cava purse string sites by the surgeon, prior to commencing cardiopulmonary bypass. Another data set was obtained right after termination of cardiopulmonary bypass. ResultsThere was a direct, significant relationship between Fick CO/CI and NICOM CO/CI measurements. More dispersion is detected when the magnitude of the measure increases, i.e., for older and larger patients. ConclusionsThere is a strong correlation between the cardiac output values derived from the Fick equation and the Aesculon non-invasive cardiac output monitor.

Use of thermodilution cardiac output overestimates diagnoses of exercise-induced pulmonary hypertension.

Two new definitions of exercise-induced pulmonary hypertension (EIPH) have emerged. Both rely on measuring cardiac output (CO), yet this remains unstandardized. In our cohort of patients undergoing invasive cardiopulmonary exercise testing, we found that using thermodilution CO rather than direct Fick CO led to a significant excess of EIPH diagnoses.

110 - Discordance between Thermodilution and Indirect Fick Cardiac Output Measurements in LVAD Patients

110 - Discordance between Thermodilution and Indirect Fick Cardiac Output Measurements in LVAD Patients

(306) - LVAD Weaning Protocol Utilizing Comprehensive Cardiopulmonary Exercise Testing to Define Cardiac Reserve Capacity

The optimal protocol for determining whether adequate LV recovery has taken place to permit LVAD explantation is not well established. Peak VO2 (pVO2) is typically the only exercise parameter utilized. We developed a protocol that integrates hemodynamic, imaging, and gas exchange measures at rest, during LVAD speed reduction, and during exercise to characterize cardiac reserve capacity and guide LVAD explant decisions. A 44 year old male with LVEF 14% demonstrated no LV recovery after CABG and required insertion of a BTT Heartware LVAD on post-op day 14. After 6 months, LVAD speed reduction to 2000 rpm led to borderline-acceptable echo parameters (LVEF 49%, LVEDD 58 mm) and a pVO2 of only 14.6 ml/kg/min. We measured VO2, peripheral O2 extraction (Ca-vO2), Fick cardiac output (CO) and pulmonary wedge pressure (PCWP) each minute during an incremental ramp exercise protocol. Exercise CO increased appropriately (7.4 to 14.6 L/min) and PCWP increment was modest (+7mmHg), which prompted us to explant the LVAD. In contrast, a 61 year old patient with a BTT LVAD demonstrated a similar pVO2 (14.1 ml/kg/min). Unlike our first patient, exercise CavO2 was normal, but he was able to augment his CO to only 8.3 L/min with a 15 mmHg increase in PCWP. LVAD explant was therefore not pursued and he underwent cardiac transplantation. Nearly identical pVO2 values in our patients with divergent relative contributions of CO and CavO2 highlight the need to consider both central cardiac and peripheral O2 extraction components of pVO2. Serial measurements of PCWP in relation to CO were particularly informative based on a 2-fold PCWP-CO slope (1.5 vs. 3.1 mmHg/L/min) in the patient not explanted. Our findings suggest that reliance on LVAD explant criteria of a pVO2 > 16 mL kg/min may not adequately reflect reserve capacity and sustained recovery potential of the native heart. Enhanced phenotyping during exercise merits further investigation to refine LVAD explant criteria.

Abstract 13702: Serum Albumin Predicts Mortality in Patients With Pulmonary Arterial Hypertension

Introduction: Low serum albumin predicts adverse outcomes in heart failure, reflecting poor nutritional status, liver dysfunction and systemic inflammation. The predictive value of albumin for mortality is not well-described in pulmonary arterial hypertension (PAH). Hypothesis: Low serum albumin will significantly predict increased mortality in patients with PAH. Methods: We constructed a database of 273 WHO group 1 PAH patients followed at our center from 03/2001 through 08/2008, including echocardiography, invasive hemodynamics, laboratory data and mortality outcomes. Serum albumin levels were available in 163 patients. The association between albumin and mortality was assessed using Cox regression and Kaplan-Meier analysis. Results: Patients were followed for a mean of 3.6 ± 2.6 years. On univariate analysis, serum albumin significantly predicted mortality with HR = 0.746 (p = 0.01, 95% CI 0.598-0.932) per 1 g/dl increase. On multivariate analysis, serum albumin significantly predicted mortality with HR = 0.491 (p = 0.009, 95% CI 0.288-0.835) per 1 g/dl increase when adjusted for age, gender, NYHA functional class, mean right atrial pressure, Fick cardiac output, connective tissue disease, right ventricular function, right atrial systolic area and serum creatinine. Patients with serum albumin below the 25th percentile (&lt;=3.3 g/dl) had significantly higher mortality by Kaplan-Meier curve analysis (p = 0.01 by log-rank test) despite similar clinical characteristics, when compared with patients with higher serum albumin. Conclusion: Higher serum albumin is an independent predictor of decreased mortality in PAH patients when adjusted for clinical, echocardiographic and hemodynamic variables. Patients with low serum albumin values had significantly higher mortality despite similar characteristics.

Disagreement between thermodilution and indirect Fick cardiac outputs in a mixed pulmonary hypertension and heart failure population

Purpose: Thermodilution and indirect Fick are two methods commonly used to measure cardiac output (CO) during right heart catheterisation (RHC). The aim of this analysis was to assess the agreement between these two techniques in a mixed pulmonary hypertension and heart failure population in daily clinical practice. Methods: A retrospective review of right heart catheter tests at a single institution from January 2012 to July 2014 was performed. Where data were available for both thermodilution and indirect Fick cardiac output, agreement was assessed using a Bland Altman analysis. Results: Of 1071 right heart catheter tests performed between January 2012 and July 2014, measurements of both thermodilution and indirect Fick CO were available for 184. The mean difference (thermodilution – Fick ± SD) was -0.61 ± 2.05 L/min (n = 184; p < 0.001). Sixty-two per cent of RHC tests demonstrated >20% difference between thermodilution and indirect Fick cardiac output. In the 70 tests for which the mean of the thermodilution and indirect Fick CO was less than 4.0 L/min, the mean difference (thermodilution – Fick ± SD) was 0.004 ± 1.65 L/min (n=70, p = 0.98), while for the 113 tests with CO above 4.0 L/min it was -1.0 ± 2.18 L/min (n=113; p <0.001). Sixty-nine per cent of RHC tests with low cardiac outputs had >20% difference between thermodilution and indirect Fick cardiac output. Conclusion: There was substantial disagreement between cardiac output measured using thermodilution and indirect Fick methods. There was a bias towards lower cardiac output measures obtained using the thermodilution technique for the overall population but not for tests with low cardiac outputs. Nevertheless, the proportion of tests for which there was >20% difference in cardiac outputs between the two techniques was very high across the whole range of cardiac outputs. These findings are consistent with previous reports of significant discrepancy between thermodilution and indirect Fick methods.

Effectiveness of phosphodiesterase-5 inhibitor therapy for portopulmonary hypertension.

Portopulmonary hypertension is associated with significant morbidity and mortality. Phosphodiesterase-5 inhibitor therapy is efficacious in other causes of WHO group I pulmonary arterial hypertension. To evaluate the efficacy and safety of phosphodiesterase-5 inhibitor therapy in patients with portopulmonary hypertension. A single-centre retrospective cohort study that included patients with a diagnosis of portopulmonary hypertension was performed. The primary outcome was change in pulmonary vascular resistance after six months of phosphodiesterase-5 inhibitor therapy. A secondary evaluation investigated the effect on other hemodynamic measurements, 6 min walk distance, functional class, safety outcomes and survival. Of 1385 patients screened, 25 patients with portopulmonary hypertension were identified, of whom 20 received a phosphodiesterase-5 inhibitor. After six months, there was a significant decrease in pulmonary vascular resistance (-236 dyn • s • cm(-5) [95% CI -343 dyn • s • cm(-5) to -130 dyn • s • cm(-5)]; P<0.001), mean pulmonary artery pressure (-8.9 mmHg [95% CI -13.7 mmHg to -4.2 mmHg]; P=0.001) and an increase in Fick cardiac output (0.9 L/min [95% CI 0.1 L/min to 1.6 L/min]; P=0.02). There was no change in 6 min walk distance. The proportion of subjects with a WHO functional class III or IV was significantly reduced at six months compared with baseline (18% versus 61%; P=0.002). Safety outcomes did not reveal any adverse events. Phosphodiesterase-5 inhibitor therapy improved hemodynamics and functional class at six months in a cohort of patients with portopulmonary hypertension.

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Introduction: iNO challenge in patients with PAH and normal pulmonary capillary wedge pressure is one method to test vasoreactivty and determine possible therapeutic options. A positive test is defined as a decrease in mean PA pressure by >10 mmHG to a level less than 40mmHG with preserved cardiac output(CO). Fick and Thermodilution(TD) methods of calculating CO are commonly used to determine change in CO. Hypothesis: We propose that there are discrepancies between the Fick CO vs TD CO following iNO challenge. Methods: Retrospective chart review of 131 patients who underwent right heart catherization over in a 1 year period in a teaching institution. A Pearson correlation was used to determine strength of correlation between pre iNO CO by Fick(PreFickCO), pre iNO CO by TD(PreTDCO), post iNO CO by Fick(PostFickCO) and post iNO CO by TD(PostTDCO). PA oxygen saturation pre and post iNO was also evaluated. They were then compared with T-test. Results: Of the 131 patients, 45 (34%) had iNO challenge at 40ppm with 100% oxygen. Twenty one (16%) had both TD and Fick calculated before and after the iNO. Pre and postFickCO had a significantly weaker correlation(r=0.47,p=0.03) when compared to Pre and Post TD CO(r= 0.9 (P<0.001). PreFickCO and PreTDCO had a relatively stronger correlation(r=0.5, p=0.01) than PostFickCO and PostTDCO(r=0.37, p=0.09). PA Saturations were significantly higher post iNO with an average of 80% vs 69% pre iNO. The Post Fick CO differed from the Post TD CO by an average of 2 L/min(p<0.001). Conclusions: In patients with PAH, the CO is important in prognosis and to determine whether the patients have a positive vasodilation challenge or not. The CO determination by both TD and Fick correlate pre-iNO but not post iNO. The weak correlation of the PostFickCO can be explained by the administration of 100% O2 with the iNO and the fact that iNO increases ventilation-perfusion matching. TD CO has a much stronger correlation pre and post iNO, as its method of calculation is not dependent on the arterial or PA saturations. Therefore, for iNO vasoreactivty testing in patients with pulmonary hypertension, TD CO should be used rather than Fick CO as it has a much stronger correlation before and after the iNO.

Abstract 18563: Pulmonary Artery Pressure Response Pattern in Heart Failure with Preserved Ejection Fraction

Background: Inefficient ventilation during exercise, defined by steep relationship between ventilation and carbon dioxide output (VE/VCO 2 ) purports a poor prognosis in heart failure (HF) patients regardless of ejection fraction (EF). However the extent to which VE/VCO 2 slope reflects hemodynamic impairment during exercise in HFpEF is unknown. We therefore investigated hemodynamic response patterns in relation to exercise gas exchange parameters in HFpEF compared to normal controls. Methods/Results: We studied consecutive patients referred for cardiopulmonary exercise testing with hemodynamic monitoring who had RER &gt;1.05 and either resting supine pulmonary capillary wedge pressure (PCWP) &gt;15 or exercise PCWP &gt;20 mmHg and LVEF &gt;0.50 (HFpEF, N=54, Age 62±11, Male 54%) and normal controls (N=16, Age 47±16, Male 37%). We measured simultaneous cardiac filling pressures, VO 2 and arterial and mixed venous blood gases (to determine Fick cardiac outputs [CO]) during every minute throughout incremental upright cycle ergometry CPET. HFpEF patients had higher VE/VCO2 slope than controls (36±7 vs. 31±7) and steeper, linear increments in PAP and PCWP relative to CO (3.6 and 2.7 mmHg/L min -1 compared to 1.6, and 1.1 mmHg/L min -1 respectively, all p&lt;0.05, Figure ).Upon stratification of the HFpEF patients by median VE/VCO2 (36) we found that higher VE/VCO2 was associated with steeper PAP slope (4.3 vs. 3.1 mmHg/L, p=0.02) and PCWP slope (3.6 vs. 2.5 mmHg/L, p=0.04) despite no difference between the two HFpEF sub-groups in resting upright PAP or PCWP. Conclusion s: We observed a linear increment in PAP and PCWP in HFpEF and controls during incremental cycle ergometry exercise. Ventilatory inefficiency is an easily measured, non-invasive variable that reflects impaired pressure-flow response patterns to exercise in patients with HFpEF.

051 Can Echocardiography Adequately Measure Cardiac Output Early After Neonatal Surgery for Congenital Heart Disease?

051 Can Echocardiography Adequately Measure Cardiac Output Early After Neonatal Surgery for Congenital Heart Disease?

Thermodilution and Fick Cardiac Outputs Differ: Impact on Pulmonary Hypertension Evaluation

The relationship between thermodilution and indirect Fick cardiac output determination methods has not been well described. To describe the relationship between these two cardiac output determination methods in patients evaluated for pulmonary hypertension and to highlight potential clinical implications. A retrospective review of charts of all adult patients who underwent a right heart catheterization (RHC) between January 1, 2007 and November 10, 2010, and participated in the pulmonary hypertension program of the pulmonary division at an academic institution was conducted. For validation, the charts of all patients who underwent RHC during the same period within the cardiology division were reviewed. A total of 198 patients underwent 213 RHCs, 79 (40%) of whom had pulmonary arterial hypertension, were included. Forty-three per cent of patients had >20% difference between thermodilution and Fick. The average difference (thermodilution - Fick ±SD) was -0.39±2.03 L⁄min (n=213; P=0.006). There was no significant difference in bias or variability between thermodilution and Fick among patients with tricuspid regurgitant jet velocity (TRJ) of <3 m⁄s versus those with TRJ >3 m⁄s (-0.41±2.10 L⁄min versus -0.36±1.93 L⁄min, respectively; P=0.87). In a multivariable analysis, the thermodilution-Fick difference increased with age (P=0.001). The presence of such discrepancy in 36% of patients evaluated for heart failure and⁄or heart transplant validated the results. In total, 37% of the 1315 procedures (213 performed by pulmonologists and 1102 performed by cardiologists) had a difference of >20% between thermodilution and Fick. Significant discrepancy exists between thermodilution and indirect Fick methods. This discrepancy potentially impacts pulmonary arterial hypertension prognostication and diagnosis, and is independent of TRJ.

Exercise Oscillatory Ventilation in Systolic Heart Failure

Background— Exercise oscillatory ventilation (EOV) is a noninvasive parameter that potently predicts outcomes in systolic heart failure (HF). However, mechanistic insights into EOV have been limited by the absence of studies relating EOV to invasive hemodynamic measurements and blood gases performed during exercise. Methods and Results— Fifty-six patients with systolic HF (mean±SEM age, 59±2 years; left ventricular ejection fraction, 30±1%) and 19 age-matched control subjects were studied with incremental cardiopulmonary exercise testing. Fick cardiac outputs, filling pressures, and arterial blood gases were measured at 1-minute intervals during exercise. We detected EOV in 45% of HF (HF+EOV) patients and in none of the control subjects. The HF+EOV group did not differ from the HF patients without EOV (HF−EOV) in age, sex, body mass index, left ventricular ejection fraction, or origin of HF. Univariate predictors of the presence of EOV in HF, among measurements performed during exercise, included higher right atrial pressure and pulmonary capillary wedge pressure and lower cardiac index (CI) but not Pa co 2 or Pa o 2 . Multivariate logistic regression identified that low exercise CI is the strongest predictor of EOV (odds ratio, 1.39 for each 1.0-L · min −1 · m −2 decrement in CI; 95% confidence interval, 1.14–1.70; P =0.001). Among HF patients with EOV, exercise CI was inversely related to EOV cycle length ( R =−0.71) and amplitude ( R =−0.60; both P &lt;0.001). In 11 HF+EOV subjects treated with 12 weeks of sildenafil, EOV cycle length and amplitude decreased proportionately to increases in CI. Conclusion— Exercise oscillatory ventilation is closely related to reduced CI and elevated filling pressures during exercise and may be an important surrogate for exercise-induced hemodynamic impairment in HF patients. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00309790.

AV Delay Optimization in CRT Based on LV dP/dt max and Fick Cardiac Output

AV Delay Optimization in CRT Based on LV dP/dt max and Fick Cardiac Output