Recalibrating the barometer: is it time to take a critical look at noninvasive approaches to measuring filling pressures?

The Effect of Mixing Iodinated Contrast Media and Ultrasound Contrast Agents on Subharmonic Signals

Subharmonic aided pressure estimation (SHAPE) is a technique that utilizes subharmonic signals from microbubble contrast agents for pressure estimation. Validation of the SHAPE technique relies on synchronous measurements of in vivo pressures using contrast microbubbles and a pressure catheter (reference standard). For the guidance and placement of pressure catheter in vivo, iodinated contrast is used with fluoroscopy. Therefore, during data acquisition for validation studies of the SHAPE technique, both contrast microbubbles and iodinated contrast are present simultaneously within the vasculature. This study aims to elucidate the effects of iodinated contrast (Visipaque, GE HealthCare) on subharmonic signal amplitude from contrast microbubbles (Definity, Lantheus Medical Imaging, Inc.). In an acrylic water tank, 0.06 mL of Definity and varied amounts of Visipaque (0.14, 0.43, 0.85, and 1.70 mL) were added to 425 mL of deionized water. Ultrasound scanning was performed with a SonixTablet scanner (BK Medical Systems) using optimized parameters for SHAPE with Definity (ftransmit/receive = 3.0/1.5 MHz; chirp down pulse). Subharmonic data was acquired and analyzed at 9 different incident acoustic outputs (n = 3). Results showed an increase in subharmonic signal amplitude from Definity microbubbles in the presence of 0.14 mL Visipaque by 2.8 ± 1.3 dB (p < .001), no change with 0.85 mL Visipaque (0.7 ± 1.2 dB; p = .09) and a decrease in subharmonic amplitude in the presence of 1.70 mL Visipaque by 1.9 ± 0.7 dB (p < .001). While statistically significant effect on subharmonic signal amplitude of Definity microbubbles was noted due to the mixture, the magnitude of the effect was minimal (~2.8 dB) and unlikely to impact in vivo SHAPE measurements.

Evaluation of Intracardiac Pressures Using Subharmonic-aided Pressure Estimation with Sonazoid Microbubbles

Purpose To investigate if the right ventricular (RV) systolic and left ventricular (LV) diastolic pressures can be obtained noninvasively using the subharmonic-aided pressure estimation (SHAPE) technique with Sonazoid microbubbles. Materials and Methods Individuals scheduled for a left and/or right heart catheterization were prospectively enrolled in this institutional review board-approved clinical trial from 2017 to 2020. A standard-of-care catheterization procedure was performed by advancing fluid-filled pressure catheters into the LV and aorta (n = 25) or RV (n = 22), and solid-state high-fidelity pressure catheters into the LV and aorta in a subset of participants (n = 18). Study participants received an infusion of Sonazoid microbubbles (GE HealthCare), and SHAPE data were acquired using a validated interface developed on a SonixTablet (BK Medical) US scanner, synchronously with the pressure catheter data. A conversion factor, derived using cuff-based pressure measurements with a SphygmoCor XCEL PWA (ATCOR) and subharmonic signal from the aorta, was used to convert the subharmonic signal into pressure values. Errors between the pressure measurements obtained using the SHAPE technique and pressure catheter were compared. Results The mean errors in pressure measurements obtained with the SHAPE technique relative to those of the fluid-filled pressure catheter were 1.6 mm Hg ± 1.5 [SD] (P = .85), 8.4 mm Hg ± 6.2 (P = .04), and 7.4 mm Hg ± 5.7 (P = .09) for RV systolic, LV minimum diastolic, and LV end-diastolic pressures, respectively. Relative to the measurements with the solid-state high-fidelity pressure catheter, the mean errors in LV minimum diastolic and LV end-diastolic pressures were 7.2 mm Hg ± 4.5 and 6.8 mm Hg ± 3.3 (P ≥ .44), respectively. Conclusion These results indicate that SHAPE with Sonazoid may have the potential to provide clinically relevant RV systolic and LV diastolic pressures. Keywords: Ultrasound-Contrast, Cardiac, Aorta, Left Ventricle, Right Ventricle ClinicalTrials.gov registration no.: NCT03245255 © RSNA, 2024.

Noninvasive Evaluation of Cardiac Chamber Pressures Using Subharmonic-Aided Pressure Estimation With Definity Microbubbles

BACKGROUND

Noninvasive and accurate assessment of intracardiac pressures has remained an elusive goal of noninvasive cardiac imaging.

OBJECTIVES

The purpose of this study was to investigate if errors in intracardiac pressures obtained noninvasively using contrast microbubbles and the subharmonic-aided pressure estimation (SHAPE) technique are <5 mm Hg.

METHODS

In a nonrandomized institutional review board-approved clinical trial (NCT03243942), patients scheduled for a left-sided and/or right-sided heart catheterization procedure and providing written informed consent were included. A standard-of-care catheterization procedure was performed advancing clinically used pressure catheters into the left and/or right ventricles and/or the aorta. After pressure catheter placement, patients received an infusion of Definity microbubbles (n = 56; 2 vials diluted in 50 mL of saline; infusion rate: 4-10 mL/min) (Lantheus Medical Imaging). Then SHAPE data was acquired using a validated interface developed on a SonixTablet scanner (BK Medical Systems) synchronously with the pressure catheter data. A conversion factor (mm Hg/dB) was derived from SHAPE data and measurements with a SphygmoCor XCEL PWA device (ATCOR Medical) and was combined with SHAPE data from the left and/or the right ventricles to obtain clinically relevant systolic and diastolic ventricular pressures.

RESULTS

The mean value of absolute errors for left ventricular minimum and end diastolic pressures were 2.9 ± 2.0 and 1.7 ± 1.2 mm Hg (n = 26), respectively, and for right ventricular systolic pressures was 2.2 ± 1.5 mm Hg (n = 11). Two adverse events occurred during Definity infusion; both were resolved.

CONCLUSIONS

These results indicate that the SHAPE technique with Definity microbubbles is encouragingly efficacious for obtaining intracardiac pressures noninvasively and accurately. (Noninvasive, Subharmonic Intra-Cardiac Pressure Measurement; NCT03243942).

Left atrial inflow propagation velocity derived by color M-mode Doppler in acute heart failure

Left atrial (LA) inflow propagation velocity from the pulmonary vein (LAIF-PV) has been proposed as a novel measure of LA reservoir function and is associated with pulmonary capillary wedge pressure in critically ill patients. However, data on LAIF-PV in acute heart failure (AHF) are lacking. We sought to examine the feasibility of measuring LAIF-PV and evaluate clinical and echocardiographic correlates of LAIF-PV in AHF. In a prospective cohort study of adults hospitalized for AHF, we used color M-mode Doppler of the pulmonary veins to obtain LAIF-PV in systole. Among 142 patients with appropriate images and no more than moderate mitral regurgitation, LAIF-PV measures were feasible in 76 patients (54%) aged 71 ± 14 years, including 68% men with left ventricular ejection fraction (LVEF) 38% ± 13. Mean LAIF-PV was 24.2 ± 5.9 cm/s. In multivariable regression analysis adjusted for age, sex, systolic blood pressure, heart rate, body mass index, New York Heart Association class, LA volume and LVEF, the only independent echocardiographic predictors of LAIF-PV were right ventricular (RV) S' [ß 0.46 cm/s per cm/s (95% CI 0.01-0.91), p = 0.045] and tricuspid annular plane systolic excursion (TAPSE) [ß 0.28 cm/s per mm (95% CI 0.02-0.54), p = 0.039]. Notably, LAIF-PV was not significantly correlated with measures of LV function, LA function or E/e'. In conclusion, LAIF-PV was measurable in 54% of patients with AHF, and lower values were associated with measures of impaired RV systolic function but not LV or LA function.

Pulmonary Congestion by Lung Ultrasound in Ambulatory Patients With Heart Failure With Reduced or Preserved Ejection Fraction and Hypertension

BACKGROUND

Although pulmonary congestion can be quantified in heart failure (HF) by means of lung ultrasonography (LUS), little is known about LUS findings (B-lines) in different HF phenotypes. This prospective cohort study investigated the prevalence and clinical and echocardiographic correlates of B-lines in ambulatory HF patients with preserved (HFpEF) or reduced (HFrEF) ejection fraction compared with hypertensive patients. We related LUS findings to 12-month HF hospitalizations and all-cause mortality.

METHODS AND RESULTS

We used LUS to examine hypertensive (n = 111), HFpEF (n = 46), and HFrEF (n = 73) patients (median age 66 y, 56% male, 79% white, and median EF 55%) undergoing clinically indicated outpatient echocardiography. B-line number was quantified offline, across 8 chest zones, blinded to clinical and echocardiographic characteristics. The proportion of patients with ≥3 B-lines was lower in hypertensive patients (13.5%) compared with both HFrEF (45.2%, P < .001) and HFpEF (34.8%; P = .05). HF patients with ≥3 B-lines had a higher risk of the composite outcome (age- and sex-adjusted hazard ratio 2.62, 95% confidence interval 1.15-5.96; P = .022).

CONCLUSIONS

When performed at the time of outpatient echocardiography, LUS findings of pulmonary congestion differ between patients with known HF and those with hypertension, and may be associated with adverse outcomes.

Non-Invasive Intra-cardiac Pressure Measurements Using Subharmonic-Aided Pressure Estimation: Proof of Concept in Humans

This study evaluated the feasibility of employing non-invasive intra-cardiac pressure estimation using subharmonic signals from ultrasound contrast agents in humans. This institutional review board-approved proof-of-concept study included 15 consenting patients scheduled for left and right heart catheterization. During the catheterization procedure, Definity was infused intra-venously at 4-10 mL/min. Ultrasound scanning was performed with a Sonix RP using pulse inversion, three incident acoustic output levels and 2.5-MHz transmit frequency. Radiofrequency data were processed and subharmonic amplitudes were compared with the pressure catheter data. The correlation coefficient between subharmonic signals and pressure catheter data ranged from -0.3 to -0.9. For acquisitions with optimum acoustic output, pressure errors between the subharmonic technique and catheter were as low as 2.6 mmHg. However, automatically determining optimum acoustic output during scanning for each patient remains to be addressed before clinical applicability can be decided.

Lung ultrasound and transthoracic impedance for noninvasive evaluation of pulmonary congestion in heart failure

BACKGROUND

In patients with heart failure, many indexes are available for noninvasive identification of pulmonary congestion: E/E' at echocardiography; plasma levels of brain natriuretic peptide (BNP) (pg/ml); number of B-lines at lung ultrasound; and transthoracic conductance [thoracic fluid content (TFC)TT = 1/Ω] at impedance cardiography (ICG).

METHODS

We obtained 75 measures from 50 patients (72 ± 10 years, NYHA 2.4 ± 0.7, ejection fraction 31 ± 7%), 25 of them studied before and after intravenous diuretics, in whom we assessed the following: E/e' from Doppler echocardiogram; BNP plasma levels; presence and number of B-lines at lung ultrasound; and TFCTT from ICG. We determined the relationship among these indexes and their change with treatment, and compared B-lines and TFC for the diagnosis of pulmonary congestion. Finally, we considered the timing and the personnel required for performing and interpreting each test.

RESULTS

A mutual relationship was observed between all the variables. After clinical improvement, changes in each variable were of similar direction and magnitude. Congestion (estimated by chest radiograph) was present in 59% of the patients: TFC value and B-line number had the best sensitivity and specificity for its detection. BNP determination and ICG assessment were performed by a nurse (15 min), and echocardiography and lung ultrasound were performed by a cardiologist (15 min).

CONCLUSION

The correlation between all indexes and their consensual change after improvement of the clinical status suggests that they all detect pulmonary congestion, and that using at least two indexes improves sensitivity and specificity. The choice among the methods may be determined by the patient characteristics or by the clinical setting.

Invasive and noninvasive assessment of exercise-induced ischemic diastolic response using pressure transducers

Left ventricular (LV) pressure curve shows early high-magnitude changes in the presence of induced ischemia. A dramatic rise in LV and left atrial end-diastolic pressures occurs within seconds to minutes in the presence of ischemia induced by dynamic or handgrip exercise as well as pacing of 38 to 183% and during short coronary balloon occlusion of 32 to 208% of baseline. Changes in relaxation or volumetric filling rate or ejection fraction were significantly less pronounced.

Similar end-diastolic abnormalities occurring mainly in patients with coronary artery disease (CAD) have been shown in noninvasive recordings obtained by pressure transducer placed over the point of maximal LV beat (pressocardiograms). Specifically, the amplitude of the A wave to total excursion of pressocardiogram showed a similar high-magnitude increase after dynamic or handgrip exercise in average by 60 to 142% of baseline; however, changes in pressocardiographic relaxation time indexes were only slightly abnormal. A well-defined “ischemic pattern” of pressocardiographic diastolic changes with handgrip, showed a high prevalence in CAD patients.

The assessment of diastolic changes in the presence of handgrip-inducible ischemia using noninvasive pressure transducers might provide after further studies a simple complementary diagnostic tool to assist in identification of patients with atypical or asymptomatic CAD.

The E-wave deceleration rate E/DT outperforms the tissue Doppler-derived index E/e' in characterizing lung remodeling in heart failure with preserved ejection fraction

Background

Diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF) may result in pulmonary congestion and lung remodeling. We evaluated the usefulness of major diastolic echocardiographic parameters and of the deceleration rate of early transmitral diastolic velocity (E/DT) in predicting lung remodeling in a rat model of HFpEF.

Methods and Results

Rats underwent aortic banding (AoB) to induce pressure overload (PO). Left ventricular hypertrophy fully developed 2 weeks after AoB. At 4 and 6 weeks, the lung weight-to-body weight ratio (LW/BW), a sensitive marker for pulmonary congestion and remodeling, dramatically increased despite preserved fractional shortening, indicating the presence of HFpEF. The time course of LW/BW was well reflected by E/DT, by the ratio of early to late transmitral diastolic velocity (E/A) and the deceleration time of E (DT), but not by the ratio of transmitral to mitral annular early diastolic velocity (E/e'). In agreement, the best correlation with LW/BW was found for E/DT (r = 0.76; p<0.0001), followed by E/A (r = 0.69; p<0.0001), DT (r = −0.62; p<0.0001) and finally E/e' (r = 0.51; p<0.001). Furthermore, analysis of receiver-operating characteristic curves for the prediction of increased LW/BW revealed excellent area under the curve values for E/DT (AUC = 0.98) and DT (AUC = 0.95), which are significantly higher than that of E/e' (AUC = 0.82). In a second approach, we also found that the new parameter E/DT correlated well with right ventricular weight index and echocardiographic measures of right ventricular systolic function.

Conclusions

The novel parameter E/DT outperforms the tissue Doppler index E/e' in detecting and monitoring lung remodeling induced by pressure overload. The results may provide a handy tool to point towards secondary lung disease in HFpEF and warrant further clinical investigations.

Renal dysfunction, restrictive left ventricular filling pattern and mortality risk in patients admitted with heart failure: a 7-year follow-up study

Background

Renal dysfunction is associated with a variety of cardiac alterations including left ventricular (LV) hypertrophy, LV dilation, and reduction in systolic and diastolic function. It is common and associated with an increased mortality risk in heart failure (HF) patients. This study was designed to evaluate whether severe diastolic dysfunction contribute to the increased mortality risk observed in HF patients with renal dysfunction.

Methods

Using Cox Proportional Hazard Models on data (N = 669) from the EchoCardiography and Heart Outcome Study (ECHOS) study we evaluated whether estimated glomerular filtration rate (eGFR) was associated with mortality risk before and after adjustment for severe diastolic dysfunction. Severe diastolic dysfunction was defined by a restrictive left ventricular filling pattern (RF) (=deceleration time < 140 ms) by Doppler echocardiography.

Results

Median eGFR was 58 ml/min/1.73 m², left ventricular ejection fraction was 33% and RF was observed in 48%. During the 7 year follow up period 432 patients died. Multivariable adjusted eGFR was associated with similar mortality risk before (Hazard Ratio(HR)_{eGFR 10 ml increase}: 0.94 (95% CI: 0.89-0.99, P = 0.024) and after (HR_{eGFR 10 ml increase}: 0.93 (0.89-0.99), P = 0.012) adjustment for RF (HR: 1.57 (1.28-1.93), P < 0.001).

Conclusions

In patients admitted with HF RF does not contribute to the increased mortality risk observed in patients with a decreased eGFR. Factors other than severe diastolic dysfunction may explain the association between renal function and mortality risk in HF patients.

Left atrium systolic and diastolic function assessment in hypertensive patients with preserved ejection fraction

Left atrium remodeling is a physiological response to pressure overload in hypertensive patients. The aim of this study is to determine the relationship between left atrium remodeling and left ventricle diastolic dysfunction in hypertensive patients with preserved systolic function.

MATERIALS AND METHODS

We conducted a prospective study on 96 hypertensive patients (48.75 ± 5.01 years, 50 men) and 96 healthy control subjects (48.17 ± 8.52 years, 56 men), whose data were all evaluated by echocardiography measuring left atrium volumes during the reservoir,conduit and pump phases. Standard indices reflecting left ventricular filling were also assessed.

RESULTS

Medium left atrium volume indexed for body surface was significantly higher in hypertensive patients – 30.87 (6.38) mL/m² vs.21.72 (2.52) mL/m². Indexed left atrium volume was strongly associated with left ventricle diastolic function (p <0.0001). When compared to normal subjects, patients with mild diastolic dysfunction had lower corrected passive emptying volumes ( p < 0.0001) and higher corrected active emptying volumes (p = 0.001), thus leading to similar corrected total emptying volumes ( p < 0.001). However, patients with moderate diastolic dysfunction had smaller active emptying volumes, but higher passive and total emptying volumes when compared to normal controls and patients with mild diastolic dysfunction.

CONCLUSIONS

Left atrium indexed volumes evaluation during the reservoir,conduit and pump phases proved to be essential for early diastolic dysfunction assessment in hypertensive patients.

Understanding the need of ventricular pressure for the estimation of diastolic biomarkers

The diastolic function (i.e., blood filling) of the left ventricle (LV) is determined by its capacity for relaxation, or the decay in residual active tension (AT) generated during systole, and its constitutive material properties, or myocardial stiffness. The clinical determination of these two factors (diastolic residual AT and stiffness) is thus essential for assessing LV diastolic function. To quantify these two factors, in our previous work, a novel model-based parameter estimation approach was proposed and successfully applied to multiple cases using clinically acquired motion and invasively measured ventricular pressure data. However, the need to invasively acquire LV pressure limits the wide application of this approach. In this study, we address this issue by analyzing the feasibility of using two kinds of non-invasively available pressure measurements for the purpose of inverse mechanical parameter estimation. The prescription of pressure based on a generic pressure-volume (P-V) relationship reported in literature is first evaluated in a set of 18 clinical cases (10 healthy and 8 diseased), finding reasonable results for stiffness but not for residual active tension. We then investigate the use of non-invasive pressure measures, now available through imaging techniques and limited by unknown or biased offset values. Specifically, three sets of physiologically realistic synthetic data with three levels of diastolic residual active tension (i.e., impaired relaxation capability) are designed to quantify the percentage error in the parameter estimation against the possible pressure offsets within the physiological limits. Maximum errors are quantified as 11 % for the magnitude of stiffness and 22 % for AT, with averaged 0.17 kPa error in pressure measurement offset using the state-of-the-art non-invasive pressure estimation method. The main cause for these errors is the limited temporal resolution of clinical imaging data currently available. These results demonstrate the potential feasibility of the estimation diastolic biomarkers with non-invasive assessment of pressure through medical imaging data.

Regional wall motion abnormality at the lateral wall disturbs correlations between tissue Doppler E/e' ratios and left ventricular diastolic performance parameters measured by invasive methods

Background

The impact of regional wall motion abnormality (RWMA) on the accuracy of heart failure with preserved ejection fraction (HFpEF) diagnosis using the E/e′ ratio, which is a non-invasive parameter of left ventricular diastolic performance, is unknown. The purpose of this study was to elucidate the impact of RWMA of the lateral wall (RWMAlat) on the correlation between E/e′ and invasive parameters of left ventricular diastolic performance.

Methods

Three hundred and eight consecutive patients undergoing tissue Doppler imaging and catheterization pressure examination were retrospectively analyzed. E/e′ was calculated as the ratio of early diastolic transmitral flow velocity to mitral annular velocity at the lateral wall. Invasive parameters including left ventricular end-diastolic pressure (LVEDP) and isovolumetric relaxation time constant (τ) were assessed based on the left ventricular pressure study. Correlation coefficients between E/e′ and these invasive parameters were analyzed and compared between cases with RWMAlat and without RWMA.

Results

LVEDP and τ correlated well with E/e′ for all 308 patients (r = 0.51 and r = 0.65, respectively). Sixty-two patients had RWMA; the remaining 246 did not have RWMAlat. We confirmed that the presence of RWMAlat weakens both the correlations between E/e′ and LVEDP (r = 0.574 vs. r = 0.381), and E/e′ and τ (r = 0.729 vs. r = 0.461).

Conclusions

Although E/e′ correlates well with parameters of left ventricular diastolic performance assessed by invasive methods, the presence of RWMAlat worsens this correlation. In cases with RWMAlat, careful assessment is required for HFpEF diagnosis because the diagnostic value of the E/e′ ratio could be decreased compared to patients without RWMAlat.

Noninvasive LV pressure estimation using subharmonic emissions from microbubbles

To develop a new noninvasive approach to quantify left ventricular (LV) pressures using subharmonic emissions from microbubbles, an ultrasound scanner was used in pulse inversion grayscale mode; unprocessed radiofrequency data were obtained with pulsed wave Doppler from the aorta and/or LV during Sonazoid infusion. Subharmonic data (in dB) were extracted and processed. Calibration factor (mm Hg/dB) from the aortic pressure was used to estimate LV pressures. Errors ranged from 0.19 to 2.50 mm Hg when estimating pressures using the aortic calibration factor, and were higher (0.64 to 8.98 mm Hg) using a mean aortic calibration factor. Subharmonic emissions from ultrasound contrast agents have the potential to noninvasively monitor LV pressures.

Utility of pulmonary hypertension for the prediction of heart failure following acute myocardial infarction

Pulmonary hypertension (PH) is usually perceived as a complication of established heart failure (HF) rather than as a predictor of HF or a marker of subclinical HF. PH may develop because of cardiac alterations that result in increased filling pressures after acute myocardial infarction (AMI). We hypothesized that PH might be a useful marker to predict the risk of HF after AMI. We studied 1,054 patients with AMI. Pulmonary artery systolic pressure (PASP) was estimated using echocardiography at the index admission and PH was defined as a PASP >35 mm Hg. The primary end point was readmission for HF at 1 year. PH was present in 471 patients (44.6%) and was strongly associated with age, decreased ejection fraction, advanced diastolic dysfunction, and moderate/severe mitral regurgitation (p <0.0001 for all comparisons). Area under the receiver operating characteristic curve was significantly higher for estimated PASP (0.74 ± 0.02) compared to other echocardiographic parameters (p = 0.02 to 0.0003). After adjustments for clinical and echocardiographic variables in a Cox model, PH was associated with a hazard ratio of 3.10 for HF (95% confidence interval 1.31 to 2.57, p <0.0001). After adding estimated PASP to a model containing clinical and echocardiographic risk factors, net reclassification improvement was 0.21 (95% confidence interval 0.11 to 0.31, p <0.0001). In conclusion, PASP integrates the severity of multiple hemodynamic determinants of increased left atrial pressures that lead to an increase in pulmonary venous pressure. In AMI, PH at the index admission is a useful marker in unmasking latent subclinical HF and predicting the development of overt HF.

Noninvasive estimation of dynamic pressures in vitro and in vivo using the subharmonic response from microbubbles

The purpose of this study was to develop and validate a noninvasive pressure estimation technique based on subharmonic emissions from a commercially available ultrasound contrast agent and scanner, unlike other studies that have either adopted a single-element transducer approach and/ or use of in-house contrast agents. Ambient pressures were varied in a closed-loop flow system between 0 and 120 mmHg and were recorded by a solid-state pressure catheter as the reference standard. Simultaneously, the ultrasound scanner was operated in pulse inversion mode transmitting at 2.5 MHz, and the unprocessed RF data were captured at different incident acoustic pressures (from 76 to 897 kPa). The subharmonic data for each pulse were extracted using band-pass filtering with averaging, and subsequently processed to eliminate noise. The incident acoustic pressure most sensitive to ambient pressure fluctuations was determined, and then the ambient pressure was tracked over 20 s. In vivo validation of this technique was performed in the left ventricle (LV) of 2 canines. In vitro, the subharmonic signal could track ambient pressure values with r(2) = 0.922 (p < 0.001), whereas in vivo, the subharmonic signal tracked the LV pressures with r(2) > 0.790 (p < 0.001) showing a maximum error of 2.84 mmHg compared with the reference standard. In conclusion, a subharmonic ultrasound-based pressure estimation technique, which can accurately track left ventricular pressures, has been established.

Phase II trials in heart failure: the role of cardiovascular imaging

The development of new therapies for heart failure (HF), especially acute HF, has proven to be quite challenging; and therapies evaluated in HF have greatly outnumbered treatments that are eventually successful in obtaining regulatory approval. Thus, the development of therapies for HF remains a vexing problem for pharmaceutical and device companies, clinical trialists, and health care professionals. Nowhere is this more apparent than in the phase II HF clinical trial, in which the goal is to determine whether an investigational agent should move forward to a phase III trial. Recent advancements in noninvasive cardiovascular imaging have allowed a new era of comprehensive phenotyping of cardiac structure and function in phase II HF trials. Besides using imaging parameters to predict success of subsequent phase III outcome studies, it is essential to also use imaging in phase II HF trials in a way that increases understanding of drug or device mechanism. Determination of the patients who would benefit most from a particular drug or device could decrease heterogeneity of phase III trial participants and lead to more successful HF clinical trials. In this review, we outline advantages and disadvantages of imaging various aspects of cardiac structure and function that are potential targets for therapy in HF, compare and contrast imaging modalities, provide practical advice for the use of cardiovascular imaging in drug development, and conclude with some novel uses of cardiac imaging in phase II HF trials.

Novel therapies in childhood heart failure: today and tomorrow

Heart failure is an important cause of morbidity and mortality in individuals of all ages. The many-faceted nature of the clinical heart failure syndrome has historically frustrated attempts to develop an overarching explanative theory. However, much useful information has been gained by basic and clinical investigation, even though a comprehensive understanding of heart failure has been elusive. Heart failure is a growing problem, in both adult and pediatric populations, for which standard medical therapy, as of 2010, can have positive effects, but these are usually limited and progressively diminish with time in most patients. If we want curative or near-curative therapy that will return patients to a normal state of health at a feasible cost, much better diagnostic and therapeutic technologies need to be developed. This review addresses the vexing group of heart failure etiologies that include cardiomyopathies and other ventricular dysfunctions of various types, for which current therapy is only modestly effective. Although there are many unique aspects to heart failure in patients with pediatric and congenital heart disease, many of the innovative approaches that are being developed for the care of adults with heart failure will be applicable to heart failure in childhood.

Prognostic significance of tissue-Doppler imaging in chronic heart failure patients on transplant waiting list: a comparative study with right heart catheterization

AIMS

Several echo-Doppler parameters, particularly the E/e' ratio, have been explored in the attempt to improve prognostic stratification in chronic heart failure (CHF) patients. In most studies, however, left ventricular filling pressure was not measured and patients with severe impairment of left ventricular function were not considered. The aim of this study was to assess the prognostic value of E/e' when compared with both traditional echo-Doppler parameters and pulmonary wedge pressure (PWP) in patients with advanced CHF.

METHODS AND RESULTS

Right heart catheterization and a two-dimensional echo-Doppler examination were performed at baseline in 49 patients (male: 88%, age: 53 ± 9 years, New York Heart Association class: 2.7 ± 0.7, left ventricular ejection fraction: 29 ± 7%). Traditional pulsed-wave and tissue Doppler velocity parameters (DT, E, SFPVF, E', and E/e') were measured. Endpoint of survival analysis was cardiac death or urgent transplantation. During a median follow-up of 47 months (range: 1-58), 18 patients had experienced a major event (cardiac death or urgent transplantation). Both DT and E/e' were significantly and independently associated with the outcome (the Cox analysis), but the strength of the association was stronger for the latter (P= 0.008 vs. P= 0.03). Moreover, DT became non-significant when adjusted for PWP, whereas E/e' preserved its prognostic value (P= 0.04). The prognostic value of E' and PWP was borderline non-significant or clearly non-significant in both univariate and multivariable analyses.

CONCLUSION

Among the echo-Doppler parameters, E/e' shows the highest predictive value in patients with advanced CHF and provides prognostic information independent of PWP. These results support the use of the feasible and easy obtainable E/e' ratio as a prognostic indicator in these patients.