The role of cardiac power and systemic vascular resistance in the pathophysiology and diagnosis of patients with acute congestive heart failure

Assessing cardiac power output values in a healthy adult population

Cardiac power output (CPO), which combines pressure and flow capacities, directly measures the heart's pumping capability. It is proposed as a superior alternative to ejection fraction in assessing cardiac function. However, there is a lack of data on CPO in healthy individuals, prompting a study to determine the cardiac power output in healthy adults in the Iranian population. This cross-sectional descriptive study investigated cardiac power in a sample of healthy individuals. Participants were recruited from healthy individuals referred to the Echocardiography department using convenience sampling. In this study, we examined the echocardiographic parameters in 173 individuals, of which 52% were men. Men exhibited significantly higher values for stroke volume, cardiac output, and cardiac power output (CPO) in both ventricles, as well as larger body surface area (BSA) and systemic mean arterial pressure (MAP), compared to women. Individuals under the age of 40 had significantly higher BSA and right ventricular cardiac output compared to those aged 40 or above. Multivariate analysis revealed that MAP, left ventricular (LV) cardiac output, LVCPO, pulmonary MAP, right ventricular (RV) CPO, and RV cardiac power index (CPI) were significant predictors of LVCPI changes. Our findings emphasize the importance of cardiac power output as a comprehensive measure of cardiac function, complementing the traditional use of ejection fraction. Further research is warranted to validate these results, establish accurate reference ranges, and explore the clinical implications of cardiac power output in various patient populations.

Acausal Modelling of Advanced-Stage Heart Failure and the Istanbul Heart Ventricular Assist Device Support with Patient Data

BACKGROUND

In object-oriented or acausal modelling, components of the model can be connected topologically, following the inherent structure of the physical system, and system equations can be formulated automatically. This technique allows individuals without a mathematics background to develop knowledge-based models and facilitates collaboration in multidisciplinary fields like biomedical engineering. This study conducts a preclinical evaluation of a ventricular assist device (VAD) in assisting advanced-stage heart failure patients in an acausal modelling environment.

METHODS

A comprehensive object-oriented model of the cardiovascular system with a VAD is developed in MATLAB/SIMSCAPE, and its hemodynamic behaviour is studied. An analytically derived pump model is calibrated for the experimental prototype of the Istanbul Heart VAD. Hemodynamics are produced under healthy, diseased, and assisted conditions. The study features a comprehensive collection of advanced-stage heart failure patients' data from the literature to identify parameters for disease modelling and to validate the resulting hemodynamics.

RESULTS

Regurgitation, suction, and optimal speeds are identified, and trends in different hemodynamic parameters are observed for the simulated pathophysiological conditions. Using pertinent parameters in disease modelling allows for more accurate results compared to the traditional approach of arbitrary reduction in left ventricular contractility to model dilated cardiomyopathy.

CONCLUSION

The current research provides a comprehensive and validated framework for the preclinical evaluation of cardiac assist devices. Due to its object-oriented nature, the featured model is readily modifiable for other cardiovascular diseases for studying the effect of pump operating conditions on hemodynamics and vice versa in silico and hybrid mock circulatory loops. The work also provides a potential teaching tool for understanding the pathophysiology of heart failure, diagnosis rationale, and degree of assist requirements.

Synchronized wearables for the detection of haemodynamic states via electrocardiography and multispectral photoplethysmography

Cardiovascular health is typically monitored by measuring blood pressure. Here we describe a wireless on-skin system consisting of synchronized sensors for chest electrocardiography and peripheral multispectral photoplethysmography for the continuous monitoring of metrics related to vascular resistance, cardiac output and blood-pressure regulation. We used data from the sensors to train a support-vector-machine model for the classification of haemodynamic states (resulting from exposure to heat or cold, physical exercise, breath holding, performing the Valsalva manoeuvre or from vasopressor administration during post-operative hypotension) that independently affect blood pressure, cardiac output and vascular resistance. The model classified the haemodynamic states on the basis of an unseen subset of sensor data for 10 healthy individuals, 20 patients with hypertension undergoing haemodynamic stimuli and 15 patients recovering from cardiac surgery, with an average precision of 0.878 and an overall area under the receiver operating characteristic curve of 0.958. The multinodal sensor system may provide clinically actionable insights into haemodynamic states for use in the management of cardiovascular disease.

Afterload-related cardiac performance is a powerful hemodynamic predictor of mortality in patients with chronic heart failure

Background

Afterload-related cardiac performance (ACP), a diagnostic parameter for septic cardiomyopathy, integrates both cardiac performance and vascular effects and could predict prognosis in septic shock.

Objectives

We hypothesized that ACP would also correlate with clinical outcomes in patients with chronic heart failure (HF).

Design

A retrospective study.

Methods

We retrospectively studied consecutive patients with chronic HF who underwent right heart catheterization and established an expected cardiac output-systemic vascular resistance (CO-SVR) curve model in chronic HF for the first time. ACP was calculated as COmeasured/COpredicted × 100%. ACP > 80%, 60% < ACP ⩽ 80%, and ACP ⩽ 60% represented less impaired, mildly impaired, and severely impaired cardiovascular function, respectively. The primary outcome was all-cause mortality, and the secondary outcome was event-free survival.

Results

A total of 965 individual measurements from 290 eligible patients were used to establish the expected CO-SVR curve model (COpredicted = 53.468 × SVR -0.799). Patients with ACP ⩽ 60% had higher serum NT-proBNP levels (P < 0.001), lower left ventricular ejection fraction (P = 0.001), and required dopamine more frequently (P < 0.001). Complete follow-up data were available in 263 of 290 patients (90.7%). After multivariate adjustment, ACP remained associated with both primary outcome (hazard ratio (HR) 0.956, 95% confidence interval (CI) 0.927-0.987) and secondary outcome (HR 0.977, 95% CI 0.963-0.992). Patients with ACP ⩽ 60% had the worst prognosis (all P < 0.001). ACP was significantly more discriminating (area under the curve of 0.770) than other conventional hemodynamic parameters in predicting mortality (Delong test, all P < 0.05).

Conclusion

ACP is a powerful independent hemodynamic predictor of mortality in patients with chronic HF. ACP and the novel CO-SVR two-dimensional graph could be useful in assessing cardiovascular function and making clinical decisions.

Clinical trial registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02664818.

Association of Systemic Vascular Resistance Analog and Cardiovascular Outcomes: The Heart and Soul Study

Background Systemic vascular resistance (SVR) is an integral component of the hemodynamic profile. Previous studies have demonstrated a close correlation between an estimated SVR analog (eSVR) based on echocardiographic methods and SVR by direct hemodynamic measurement. However, the prognostic impact of eSVR remains unestablished. Methods and Results Study participants with established coronary artery disease from the Heart and Soul Study formed this study cohort. We defined Doppler-derived eSVR as the ratio of systolic blood pressure to left ventricular outflow tract velocity time integral. Study participants were separated based on baseline eSVR tertile: <5.6, 5.6 to <6.9, and ≧6.9. An elevated eSVR was defined as an eSVR in the third tertile (≧6.9). Follow-up eSVR was calculated at the fifth year of checkup. Cardiovascular outcomes included heart failure, major cardiovascular events, and all-cause death. Among the 984 participants (67±11 years old, 82% men), subjects with the highest baseline eSVR tertile were the oldest, with the highest systolic blood pressure and lowest left ventricular outflow tract velocity time integral. A higher eSVR was associated with increased risk of heart failure, major cardiovascular events, and death. The hazard ratio for major cardiovascular events was 1.38 (95% CI, 1.02-1.86, P=0.03) for subjects with the highest eSVR tertile compared with the lowest. In addition, those with a persistently elevated eSVR during follow-up had the most adverse outcomes. Conclusions An elevated eSVR, derived by the ratio of systolic blood pressure and left ventricular outflow tract velocity time integral, was more closely correlated with cardiovascular events than systolic blood pressure alone. Repeatedly elevated eSVR was associated with more adverse outcomes.

Effects of early phase 1 cardiac rehabilitation on cardiac function evaluated by impedance cardiography in patients with coronary heart disease and acute heart failure

Purpose

The purpose of the study was to access the impact of phase 1 cardiac rehabilitation (CR) on cardiac function and hemodynamic changes in patients with coronary heart disease (CHD) and acute heart failure (AHF).

Materials and methods

A total of 98 patients with CHD and AHF were recruited and randomized into two groups. Control group received standard pharmacotherapy and CR group received standard pharmacotherapy combined phase 1 CR. NT-proBNP and hemodynamic parameters measured by impedance cardiography (ICG) were estimated at baseline and at the end of treatment period.

Results

Phase 1 CR combined routine medical treatment could lower NT-proBNP levels. The percentage of high-risk patients was significantly decreased in CR group, although the post-treatment NT-proBNP level between control group and CR group showed no significant differences. Similarly, most hemodynamic parameters improved in the CR group, but not in the control group, suggesting that phase 1 CR in combination with the standard pharmacotherapy improved hemodynamic characteristics by elevating cardiac output, ameliorating preload, improving systolic and diastolic function, and relieving afterload, although the post-treatment hemodynamic parameters showed no statistically significant differences between the control group and the CR group.

Conclusion

Phase 1 CR combined routine medication can improve cardiac function and hemodynamic characteristics in patients with CHD and AHF. Thus, recommendation of phase 1 CR to stable patients is necessary.

Prognostic significance of resting cardiac power to left ventricular mass and E/e’ ratio in heart failure with preserved ejection fraction

Background

Cardiac power-to-left ventricular mass (power/mass) is an index reflecting the muscular hydraulic pump capability of the heart, and the E/e’ ratio is a specific indicator for identifying increased left ventricular filling pressure. Limited data exist regarding the prognostic value of incorporating power/mass and E/e’ ratio in heart failure with preserved ejection fraction (HFpEF).

Materials and methods

In total, 475 patients with HFpEF from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial with complete baseline echocardiography data were included in our analysis. Patients were categorized into four groups according to power/mass and E/e’ ratio. The risk of outcomes was examined using Cox proportional hazards models and competing risk models.

Results

Patients with low power/mass and high E/e’ were more likely to be males (60.5%), with higher waist circumference, and had a higher prevalence of diabetes (52.1%), atrial fibrillation (50.4%), and lower estimated glomerular filtration rate (eGFR). Combined resting power/mass and E/e’ have graded correlations with left ventricular (LV) dysfunction and clinical outcomes in patients with HFpEF. After multivariable adjustments, an integrative approach combining power/mass and E/e’ remained to be a powerful prognostic predictor, with the highest HRs of clinical outcomes observed in patients with low power/mass and high E/e’ (all-cause mortality: HR 3.45; 95% CI: 1.69–7.05; P = 0.001; hospitalization for heart failure: HR 3.27; 95% CI: 1.60–6.67; P = 0.001; and primary endpoint: HR 3.07; 95% CI: 1.73–5.42; P &lt; 0.001).

Conclusion

In patients with HFpEF, an echo-derived integrated approach incorporating resting power/mass and E/e’ ratio remained to be a powerful prognosis predictor and may be useful to risk-stratify patients with this heterogeneous syndrome.

Clinical Trial Registration

[https://clinicaltrials.gov], identifier [NCT00094302].

Cardiac Complications of Hypertensive Emergency: Classification, Diagnosis and Management Challenges

While mortality in patients with hypertensive emergency has significantly improved over the past decades, the incidence and complications associated with acute hypertension-mediated organ damage have not followed a similar trend. Hypertensive emergency is characterized by an abrupt surge in blood pressure, mostly occurring in people with pre-existing hypertension to result in acute hypertension-mediated organ damage. Acute hypertension-mediated organ damage commonly affects the cardiovascular system, and present as acute heart failure, myocardial infarction, and less commonly, acute aortic syndrome. Elevated cardiac troponin with or without myocardial infarction is one of the major determinants of outcome in hypertensive emergency. Despite being an established entity distinct from myocardial infarction, myocardial injury has not been systematically studied in hypertensive emergency. The current guidelines on the evaluation and management of hypertensive emergencies limit the cardiac troponin assay to patients presenting with features of myocardial ischemia and acute coronary syndrome, resulting in underdiagnosis, especially of atypical myocardial infarction. In this narrative review, we aimed to give an overview of the epidemiology and pathophysiology of hypertensive emergencies, highlight challenges in the evaluation, classification, and treatment of hypertensive emergency, and propose an algorithm for the evaluation and classification of cardiac acute hypertension-mediated organ damage.

Noninvasive echocardiographic cardiac power output predicts mortality in cardiac intensive care unit patients

BACKGROUND

Low cardiac power output (CPO), measured invasively, can identify critically ill patients at increased risk of adverse outcomes, including mortality. We sought to determine whether non-invasive, echocardiographic CPO measurement was associated with mortality in cardiac intensive care unit (CICU) patients.

METHODS

Patients admitted to CICU between 2007 and 2018 with echocardiography performed within one day (before or after) admission and who had available data necessary for calculation of CPO were evaluated. Multivariable logistic regression determined the relationship between CPO and adjusted hospital mortality.

RESULTS

A total of 5,585 patients (age of 68.3 ± 14.8 years, 36.7% female) were evaluated with admission diagnoses including acute coronary syndrome (ACS) in 56.7%, heart failure (HF) in 50.1%, cardiac arrest (CA) in 12.2%, shock in 15.5%, and cardiogenic shock (CS) in 12.8%. The mean left ventricular ejection fraction (LVEF) was 47.3 ± 16.2%, and the mean CPO was 1.04 ± 0.37 W. There were 419 in-hospital deaths (7.5%). CPO was inversely associated with the risk of hospital mortality, an association that was consistent among patients with ACS, HF, and CS. On multivariable analysis, higher CPO was associated with reduced hospital mortality (OR 0.960 per 0.1 W, 95CI 0.0.926-0.996, P = .03). Hospital mortality was particularly high in patients with low CPO coupled with reduced LVEF, increased vasopressor requirements, or higher admission lactate.

CONCLUSIONS

Echocardiographic CPO was inversely associated with hospital mortality in unselected CICU patients, particularly among patients with increased lactate and vasopressor requirements. Routine calculation and reporting of CPO should be considered for echocardiograms performed in CICU patients.

Tracking Peripheral Artery Motion and Vascular Resistance with a Multi-Modal Wearable Sensor Under Pressure Perturbations

Peripheral artery status is a key physiological indicator of the body's cardiovascular response to both acute and chronic medical conditions. In this paper, peripheral artery behavior is tracked non-invasively by combining a photo plethysmograph (PPG) sensor and a piezoelectric (polyvinylidene difluoride, PVDF) sensor, while applying an outside pressure-varying cuff. A simple mechanical model for the local artery and tissue captures time- and pressure-dependent features present in the PPG and PVDF signals with respect to applied cuff pressure, during maneuvers applied to multiple swine subjects to perturb blood pressure and vascular resistance. These behaviors provide insight into feasibility and robustness of cardiovascular property identification by multi-modal non-invasive wearable sensing. This is found to help refine non-invasive blood pressure measurements and estimation of systemic vascular resistance (SVR) and blood pressure (BP) using selected features of sensor amplitude versus applied cuff pressure.

Towards precision medicine in heart failure

The number of therapies for heart failure (HF) with reduced ejection fraction has nearly doubled in the past decade. In addition, new therapies for HF caused by hypertrophic and infiltrative disease are emerging rapidly. Indeed, we are on the verge of a new era in HF in which insights into the biology of myocardial disease can be matched to an understanding of the genetic predisposition in an individual patient to inform precision approaches to therapy. In this Review, we summarize the biology of HF, emphasizing the causal relationships between genetic contributors and traditional structure-based remodelling outcomes, and highlight the mechanisms of action of traditional and novel therapeutics. We discuss the latest advances in our understanding of both the Mendelian genetics of cardiomyopathy and the complex genetics of the clinical syndrome presenting as HF. In the phenotypic domain, we discuss applications of machine learning for the subcategorization of HF in ways that might inform rational prescribing of medications. We aim to bridge the gap between the biology of the failing heart, its diverse clinical presentations and the range of medications that we can now use to treat it. We present a roadmap for the future of precision medicine in HF.

Intra-Aortic Balloon Pumping in Acute Decompensated Heart Failure With Hypoperfusion: From Pathophysiology to Clinical Practice

Trials on intra-aortic balloon pump (IABP) use in cardiogenic shock related to acute myocardial infarction have shown disappointing results. The role of IABP in cardiogenic shock treatment remains unclear, and new (potentially more potent) mechanical circulatory supports with arguably larger device profile are emerging. A reappraisal of the physiological premises of intra-aortic counterpulsation may underpin the rationale to maintain IABP as a valuable therapeutic option for patients with acute decompensated heart failure and tissue hypoperfusion. Several pathophysiological features differ between myocardial infarction- and acute decompensated heart failure-related hypoperfusion, encompassing cardiogenic shock severity, filling status, systemic vascular resistances rise, and adaptation to chronic (if preexisting) left ventricular dysfunction. IABP combines a more substantial effect on left ventricular afterload with a modest increase in cardiac output and would therefore be most suitable in clinical scenarios characterized by a disproportionate increase in afterload without profound hemodynamic compromise. The acute decompensated heart failure syndrome is characterized by exquisite afterload-sensitivity of cardiac output and may be an ideal setting for counterpulsation. Several hemodynamic variables have been shown to predict response to IABP within this scenario, potentially guiding appropriate patient selection. Finally, acute decompensated heart failure with hypoperfusion may frequently represent an end stage in the heart failure history: IABP may provide sufficient hemodynamic support and prompt end-organ function recovery in view of more definitive heart replacement therapies while preserving ambulation when used with a transaxillary approach.

Cardioprotective shock management: monitoring and supportive therapies

Cardiogenic shock is a highly lethal syndrome, leading to rapid death or secondary multiorgan damage, but current shock therapies, including mechanical support devices, also have a significant side effect profile. The overarching goal of shock therapy is ensuring long-term survival with good quality of life. This implies averting death, modifying the disease course by promoting heart recovery and avoiding additional cardiac damage, protecting other organs, and circumventing complications. Monitoring and supportive therapies are subordinate to these goals. Rather than merely following preconceived notions, the rapid evolution in mechanical support technology requires iterative and critical review of the benefits of current procedures, protocols and drugs in view of their overall contribution to the therapeutic goals. This article discusses various monitoring and supportive pharmaceutical modalities typically used in patients with cardiogenic shock requiring mechanical support.

Hemodynamic Profiles of Cardiogenic Shock Depending on Their Etiology

The pathophysiology of cardiogenic shock (CS) varies depending on its etiology, which may lead to different hemodynamic profiles (HP) and may help tailor therapy. We aimed to assess the HP of CS patients according to their etiologies of acute myocardial infarction (AMI) and acute decompensated chronic heart failure (ADCHF). We included patients admitted for CS secondary to ADCHF and AMI. HP were measured before the administration of any inotrope or vasopressor. Systemic Vascular Resistances index (SVRi), Cardiac Index (CI), and Cardiac Power Index (CPI) were measured by trans-thoracic Doppler echocardiography on admission. Among 37 CS patients, 28 had CS secondary to ADCHF or AMI and were prospectively included. The two groups were similar in terms of demographic data and shock severity criteria. AMI CS was associated with lower SVRi compared to CS related to ADCHF: 2010 (interquartile range (IQR): 1895-2277) vs. 2622 (2264-2993) dynes-s·cm^-5·m^-2 (p = 0.002). A trend toward a higher CI was observed: respectively 2.13 (1.88-2.18) vs. 1.78 (1.65-1.96) L·min^-1·m^-2 (p = 0.067) in AMICS compared to ADCHF. CS patients had different HP according to their etiologies. AMICS had lower SVR and tended to have a higher CI compared to ADHF CS. These differences should be taken into account for patient selection in future research.

Contemporary Management of Acute Decompensated Heart Failure and Cardiogenic Shock

Cardiogenic shock (CS) is a life-threatening condition characterized by end-organ hypoperfusion and hypoxia primarily due to cardiac dysfunction and low cardiac output. Unfortunately, the mortality and morbidity associated with CS have remained high despite notable advances in heart failure management. Treatment should be carefully guided by hemodynamics assessment. Although inotropes, vasopressors, mechanical circulatory support, and catheter intervention for critical valve lesion are not always recommended, they are helpful in selected patients. Early diagnosis, accurate hemodynamic assessment, and prompt therapeutic intervention are crucial in the management of acute decompensated heart failure with CS.

Does a Gradient-Adjusted Cardiac Power Index Improve Prediction of Post-Transcatheter Aortic Valve Replacement Survival Over Cardiac Power Index?

PURPOSE

Cardiac power (CP) index is a product of mean arterial pressure (MAP) and cardiac output (CO). In aortic stenosis, however, MAP is not reflective of true left ventricular (LV) afterload. We evaluated the utility of a gradient-adjusted CP (GCP) index in predicting survival after transcatheter aortic valve replacement (TAVR), compared to CP alone.

MATERIALS AND METHODS

We included 975 patients who underwent TAVR with 1 year of follow-up. CP was calculated as (CO×MAP)/[451×body surface area (BSA)] (W/m²). GCP was calculated using augmented MAP by adding aortic valve mean gradient (AVMG) to systolic blood pressure (CP1), adding aortic valve maximal instantaneous gradient to systolic blood pressure (CP2), and adding AVMG to MAP (CP3). A multivariate Cox regression analysis was performed adjusting for baseline covariates. Receiver operator curves (ROC) for CP and GCP were calculated to predict survival after TAVR.

RESULTS

The mortality rate at 1 year was 16%. The mean age and AVMG of the survivors were 81±9 years and 43±4 mm Hg versus 80±9 years and 42±13 mm Hg in the deceased group. The proportions of female patients were similar in both groups (p=0.7). Both CP and GCP were independently associated with survival at 1 year. The area under ROCs for CP, CP1, CP2, and CP3 were 0.67 [95% confidence interval (CI), 0.62-0.72], 0.65 (95% CI, 0.60-0.70), 0.66 (95% CI, 0.61-0.71), and 0.63 (95% CI 0.58-0.68), respectively.

CONCLUSION

GCP did not improve the accuracy of predicting survival post TAVR at 1 year, compared to CP alone.

Patient-specific 3D-printed coronary models based on coronary computed tomography angiography volumes to investigate flow conditions in coronary artery disease

BACKGROUND

3D printed patient-specific coronary models have the ability to enable repeatable benchtop experiments under controlled blood flow conditions. This approach can be applied to CT-derived patient geometries to emulate coronary flow and related parameters such as Fractional Flow Reserve (FFR).

METHODS

This study uses 3D printing to compare such benchtop FFR results with a non-invasive CT-FFR research software algorithm and catheter based invasive FFR (I-FFR) measurements. Fifty-two patients with a clinical indication for I-FFR underwent a research Coronary CT Angiography (CCTA) prior to catheterization. CT images were used to measure CT-FFR and to generate patient-specific 3D printed models of the aortic root and three main coronary arteries. Each patient-specific model was connected to a programmable pulsatile pump and benchtop FFR (B-FFR) was derived from pressures measured proximal and distal to coronary stenosis using pressure transducers. B-FFR was measured for two coronary outflow rates ('normal', 250 ml min^-1; and 'hyperemic', 500 ml min^-1) by adjusting the model's distal coronary resistance.

RESULTS

Pearson correlations and ROC AUC were calculated using invasive I-FFR as reference. The Pearson correlation factor of CT-FFR and B-FFR-500 was 0.75 and 0.71, respectively. Areas under the ROCs for CT-FFR and B-FFR-500 were 0.80 (95%CI: 0.70-0.87) and 0.81 (95%CI: 0.64-0.91) respectively.

CONCLUSION

Benchtop flow simulations with 3D printed models provide the capability to measure pressure changes at any location in the model, for ultimately emulating the FFR at several simulated physiological blood flow conditions.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/show/NCT03149042.

Deep phenotyping of cardiac function in heart transplant patients using cardiovascular system models

KEY POINTS

Right heart catheterization data from clinical records of heart transplant patients are used to identify patient-specific models of the cardiovascular system. These patient-specific cardiovascular models represent a snapshot of cardiovascular function at a given post-transplant recovery time point. This approach is used to describe cardiac function in 10 heart transplant patients, five of which had multiple right heart catheterizations allowing an assessment of cardiac function over time. These patient-specific models are used to predict cardiovascular function in the form of right and left ventricular pressure-volume loops and ventricular power, an important metric in the clinical assessment of cardiac function. Outcomes for the longitudinally tracked patients show that our approach was able to identify the one patient from the group of five that exhibited post-transplant cardiovascular complications.

ABSTRACT

Heart transplant patients are followed with periodic right heart catheterizations (RHCs) to identify post-transplant complications and guide treatment. Post-transplant positive outcomes are associated with a steady reduction of right ventricular and pulmonary arterial pressures, toward normal levels of right-side pressure (about 20 mmHg) measured by RHC. This study shows that more information about patient progression is obtained by combining standard RHC measures with mechanistic computational cardiovascular system models. The purpose of this study is twofold: to understand how cardiovascular system models can be used to represent a patient's cardiovascular state, and to use these models to track post-transplant recovery and outcome. To obtain reliable parameter estimates comparable within and across datasets, we use sensitivity analysis, parameter subset selection, and optimization to determine patient-specific mechanistic parameters that can be reliably extracted from the RHC data. Patient-specific models are identified for 10 patients from their first post-transplant RHC, and longitudinal analysis is carried out for five patients. Results of the sensitivity analysis and subset selection show that we can reliably estimate seven non-measurable quantities; namely, ventricular diastolic relaxation, systemic resistance, pulmonary venous elastance, pulmonary resistance, pulmonary arterial elastance, pulmonary valve resistance and systemic arterial elastance. Changes in parameters and predicted cardiovascular function post-transplant are used to evaluate the cardiovascular state during recovery of five patients. Of these five patients, only one showed inconsistent trends during recovery in ventricular pressure-volume relationships and power output. At the four-year post-transplant time point this patient exhibited biventricular failure along with graft dysfunction while the remaining four exhibited no cardiovascular complications.

Acute heart failure: More questions than answers

Acute heart failure (AHF) is a life-threatening condition with a dramatic burden in terms of symptoms, morbidity and mortality. It is a specific syndrome requiring urgent, life-saving treatment. Multiple specific pathophysiologic mechanisms may be involved, including congestion, inflammation, and neurohormonal activation. This process eventually leads to symptoms, end-organ damage, and adverse outcomes. Clinical presentation varies, but it almost universally includes worsening of congestion associated with different degrees of hypoperfusion. Due to substantial early symptoms burden and high morbidity and mortality, patients with AHF require intensive monitoring and intravenous treatment. However, beyond variable improvement in congestion, none of the available intravenous therapies for AHF was shown to improve longer term outcomes. Although oral treatment with guideline-directed therapies for stable patients with HF and reduced ejection fraction (HFrEF) before discharge may fully prevent subsequent episodes, proof that this strategy may benefit patients is lacking. First, most patients with AHF have preserved EF (HFpEF) where no therapies have been shown to be effective. Second, all therapies developed for patients with HFrEF were tested for efficacy on outcomes in patients who were stable without recent AHF. Hence, the implementation of these chronic therapies during an AHF episode is untested. Third, the problem to better treat AHF patients in their early phase remains crucial with treatment strategies largely untested, yet. Further studies targeting AHF specific mechanisms, such as inflammation and end-organ damage, and finding effective intravenous drugs remain therefore warranted.

The apelinergic system: a perspective on challenges and opportunities in cardiovascular and metabolic disorders

The apelinergic pathway has been generating increasing interest in the past few years for its potential as a therapeutic target in several conditions associated with the cardiovascular and metabolic systems. Indeed, preclinical and, more recently, clinical evidence both point to this G protein-coupled receptor as a target of interest in the treatment of not only cardiovascular disorders such as heart failure, pulmonary arterial hypertension, atherosclerosis, or septic shock, but also of additional conditions such as water retention/hyponatremic disorders, type 2 diabetes, and preeclampsia. While it is a peculiar system with its two classes of endogenous ligand, the apelins and Elabela, its intricacies are a matter of continuing investigation to finely pinpoint its potential and how it enables crosstalk between the vasculature and organ systems of interest. In this perspective article, we first review the current knowledge on the role of the apelinergic pathway in the above systems, as well as the associated therapeutic indications and existing pharmacological tools. We also offer a perspective on the challenges and potential ahead to advance the apelinergic system as a target for therapeutic intervention in several key areas.

Cardiac power output accurately reflects external cardiac work over a wide range of inotropic states in pigs

BACKGROUND

Cardiac power output (CPO), derived from the product of cardiac output and mean aortic pressure, is an important yet underexploited parameter for hemodynamic monitoring of critically ill patients in the intensive-care unit (ICU). The conductance catheter-derived pressure-volume loop area reflects left ventricular stroke work (LV SW). Dividing LV SW by time, a measure of LV SW min^- 1 is obtained sharing the same unit as CPO (W). We aimed to validate CPO as a marker of LV SW min^- 1 under various inotropic states.

METHODS

We retrospectively analysed data obtained from experimental studies of the hemodynamic impact of mild hypothermia and hyperthermia on acute heart failure. Fifty-nine anaesthetized and mechanically ventilated closed-chest Landrace pigs (68 ± 1 kg) were instrumented with Swan-Ganz and LV pressure-volume catheters. Data were obtained at body temperatures of 33.0 °C, 38.0 °C and 40.5 °C; before and after: resuscitation, myocardial infarction, endotoxemia, sevoflurane-induced myocardial depression and beta-adrenergic stimulation. We plotted LVSW min^- 1 against CPO by linear regression analysis, as well as against the following classical indices of LV function and work: LV ejection fraction (LV EF), rate-pressure product (RPP), triple product (TP), LV maximum pressure (LVP_max) and maximal rate of rise of LVP (LV dP/dt_max).

RESULTS

CPO showed the best correlation with LV SW min^- 1 (r² = 0.89; p < 0.05) while LV EF did not correlate at all (r² = 0.01; p = 0.259). Further parameters correlated moderately with LV SW min^- 1 (LVP_max r² = 0.47, RPP r² = 0.67; and TP r² = 0.54). LV dP/dt_max correlated worst with LV SW min^- 1 (r² = 0.28).

CONCLUSION

CPO reflects external cardiac work over a wide range of inotropic states. These data further support the use of CPO to monitor inotropic interventions in the ICU.

Vascular Parameters for Ambulatory Monitoring of Congestive Heart Failure Patients: Proof of Concept

PURPOSE

Prompt detection of congestion is an essential target in order to prevent heart failure (HF) related hospitalization, being ambulatory monitoring a promising strategy to do so. A successful non-invasive ambulatory monitoring system requires automatic devices for physiological data recording; these data must give information about HF deterioration early enough to predict HF-related adverse events. This work aims to evaluate seven vascular parameters for the ambulatory monitoring of congestive heart failure patients.

METHODS

Seven vascular parameters are proposed as indicators of HF deterioration. These parameters are obtained using venous occlusion plethysmography; a technique that uses hardware able of being miniaturized and easily integrated into wearables for ambulatory monitoring. The ability of the proposed vascular parameters to detect congestion is evaluated in eight healthy volunteers and ten congestive heart failure patients with different congestion levels-mild, moderate and severe.

RESULTS

Most parameters distinguish between healthy volunteers and heart failure patients, and some of them present significant differences between volunteers and low levels of congestion-mild or moderate.

CONCLUSION

Home monitoring of some of the proposed parameters could detect HF deterioration on its onset and alert to health personnel.

Hemodynamic response to fluid removal during hemodialysis: categorization of causes of intradialytic hypotension

Background

Intradialytic hypotension is a clinically significant problem, however, the hemodynamics that underlie ultrafiltration and consequent hypotensive episodes has not been studied comprehensively.

Methods

Intradialytic cardiac output, cardiac power and peripheral resistance changes from pretreatment measurements were evaluated using a novel regional impedance cardiographic device (NICaS, NI Medical, Peta Tikva, Israel) in 263 hemodialysis sessions in 54 patients in dialysis units in the USA and Brazil with the goal of determining the various hemodynamic trends as blood pressure decreases.

Results

Hypotensive episodes occurred in 99 (13.5%) of 736 intra- and postdialytic evaluations. The hemodynamic profiles of the episodes were categorized: (i) The cardiac power index significantly decreased in 35% of episodes by 36%, from 0.66 [95% confidence interval (CI) 0.60-0.72] to 0.43 (95% CI 0.37-0.48) [w/m2] with a small reduction in the total peripheral resistance index. (ii) The total peripheral resistance index significantly decreased in 37.4% of episodes by 33%, from 3342 (95% CI 2824-3859) to 2251 (95% CI 1900-2602) [dyn × s/cm5 × m2] with a small reduction in the cardiac power index. (iii) Both the cardiac power index and total peripheral resistance index significantly decreased in 27.3% of episodes, the cardiac power index by 25% from 0.63 (95% CI 0.57-0.70) to 0.48 (95% CI 0.42-0.53) [w/m2] and the total peripheral resistance index by 23% from 2964 (95% CI 2428-3501) to 2266 (95% CI 1891-2642).

Conclusions

The hemodynamic profiles clearly define specific hemodynamic mechanisms of cardiac power reduction and/or vasodilatation as underlying intradialytic hypotensive episodes. A reduction in cardiac power (reduction of both blood pressure and cardiac output) could be the result of preload reduction due to a high ultrafiltration rate with not enough refilling or low target weight. A reduction in peripheral resistance (reduction in blood pressure and increase in cardiac output) could be the result of relative vasodilatation as arteries do not contract to compensate for volume reduction due to autonomous dysfunction. As both phenomena are independent, they may appear at the same time. Based on these results, a reduction of ultrafiltration rate and an increase in target weight to improve preload or immediate therapeutic actions to increase peripheral resistance are rational measures that could be taken to maintain blood pressure and prevent hypotensive ischemic complications in dialysis patients.

Perturbations of pulsatile hemodynamics and clinical outcomes in patients with acute heart failure and reduced, mid-range or preserved ejection fraction

Background

Heart failure with mid-range ejection fraction (HFmrEF) has been proposed as a new phenotype of heart failure. We therefore investigated the pulsatile hemodynamic characteristics and outcomes in patients with HFmrEF, in comparison with those with reduced (HFrEF) or preserved (HFpEF) ejection fraction.

Methods

The study was composed of two cohorts of patients hospitalized due to acute heart failure. Pulsatile hemodynamic measures, including carotid-femoral pulse wave velocity (cf-PWV), carotid pulse pressure (cPP), amplitude of the backward pressure wave (Pb) and carotid augmentation index (cAIx), were recorded on admission and before discharge in Cohort A (n = 230, mean age 69.9 ±15.4 years), and long-term follow-up was performed in Cohort B (n = 2677, mean age 76.3 ± 33.4 years).

Results

In Cohort A, patients with HFmrEF had persistently greater cf-PWV, cPP, Pb, and cAI than those with HFrEF, both on admission and before discharge. In contrast, patients with HFmrEF and HFpEF had similar pulsatile hemodynamic characteristics. In cohort B, patients with HFmrEF and HFrEF had similar three-year mortality rates and both were significantly higher than that in patients with HFpEF (both P values < 0.05).

Conclusions

Patients with HFmrEF were characterized by a worse left ventricular systolic function than patients with HFpEF and excessive wave reflections than patients with HFrEF. Future studies are required to confirm that the unfavorable ventriculo-arterial coupling in HFmrEF might play a role in the pathogenesis of high long-term mortality in these patients.

The value of non-invasive measurement of cardiac output and total peripheral resistance to categorize significant changes of intradialytic blood pressure: a prospective study

Background

Blood pressure (BP) is currently the main hemodynamic parameter used to assess the influence of fluid removal during hemodialysis session. Since BP is dependent on cardiac output (CO) and total peripheral resistance (TPRI), investigating these parameters may help to better understand the influence of fluid removal on patient’s hemodynamics. We used a novel non-invasive whole-body bio-impedance cardiography device, recently validated in hemodialysis patients, to examine mechanisms of intradialytic hemodynamics in a Chinese dialysis population.

Methods

Chronic hemodialysis patients in Sichuan Provincial People’s Hospital were enrolled. Demographic data and dialysis prescriptions were collected. Hemodynamic measurements were made pre-treatment, every 20 min during treatment and immediately after treatment in each random dialysis session. These included blood pressure, cardiac index (CI), total peripheral resistance (TPRI) and cardiac power index (CPI). Patients were divided into 5 hemodynamic groups as per their major hemodynamic response to fluid removal: low CPI, low TPRI, high TPRI, High CPI and those with normal hemodynamics.

Results

Twenty-seven patients were enrolled, with 12 (44.4%) males. The average age was 65 ± 12 y. The average body mass index (BMI) was 23.7 ± 3.9 kg/m2. 12 (44.4%) patients were diabetic. Three hundred twenty-four hemodynamic measurements were made. Weight, BMI, total fluid removal, pretreatment systolic BP, CI, TPRI and CI differed significantly among the 5 hemodynamic groups.11.1% of patients had low CPI, 25.9% had low TPRI, 18.5% had high CPI, 3.7% had high TPRI and 40.7% had normal hemodynamics. Hemodynamic differences among the 5 subgroups were significant.

Conclusion

This technology provides multi-dimensional insight into intradialytic hemodynamic parameters, which may be more informative than blood pressure only. Using hemodynamic parameters to describe patients’ status is more specific and accurate, and could help to work out specific and effective therapeutic actions according to underlying abnormalities.

Doppler echocardiography for assessment of systemic vascular resistances in cardiogenic shock patients

OBJECTIVE

Impaired vascular tone plays an important role in cardiogenic shock. Doppler echocardiography provides a non-invasive estimation of systemic vascular resistance. The aim of the present study was to compare Doppler echocardiography with the transpulmonary thermodilution method for the assessment of systemic vascular resistance in patients with cardiogenic shock.

METHODS

This prospective monocentric comparison study was conducted in a single cardiology intensive care unit (Hopital Nord, Marseille, France). We assessed the systemic vascular resistance index by both echocardiography and transpulmonary thermodilution in 28 patients admitted for cardiogenic shock, on admission and after the introduction of an inotrope or vasopressor treatment.

RESULTS

A total of 35 paired echocardiographic and transpulmonary thermodilution estimations of the systemic vascular resistance index were compared. Echocardiography values ranged from 1309 to 3526 dynes.s.m²/cm⁵ and transpulmonary thermodilution values ranged from 1320 to 3901 dynes.s.m²/cm⁵. A statistically significant correlation was found between echocardiography and transpulmonary thermodilution (r=0.86, 95% confidence interval (CI) 0.74, 0.93; P<0.0001). The intraclass correlation coefficient was 0.84 (95% CI 0.72, 0.92). The mean bias was -111.95 dynes.s.m²/cm⁵ (95% CI -230.06, 6.16). Limits of agreement were -785.86, 561.96.

CONCLUSIONS

Doppler echocardiography constitutes an accurate non-invasive alternative to transpulmonary thermodilution to provide an estimation of systemic vascular resistance in patients with cardiogenic shock.

Prognostic value of the absolute lymphocyte count in patients admitted for acute heart failure

BACKGROUND

Low relative lymphocyte count is an important prognostic marker in acute heart failure (AHF); however, it could be influenced by other abnormalities in white cells count. Our purpose is to evaluate if low absolute lymphocyte count (ALC) is an independent predictor of events in patients with AHF.

METHODS

In a retrospective analysis, we included 309 patients with AHF, divided into two groups according to the median value of ALC at admission (1410 cells/μl). The primary end point was all-cause mortality or urgent heart transplantation within 1 year.

RESULTS

Patients with low ALC were older and had more comorbidity, namely atrial fibrillation, chronic kidney disease, chronic obstructive pulmonary disease and anemia. Low ALC was associated with higher all-cause mortality or urgent heart transplantation at 1 year (24.3 vs 13.0%; P = 0.012). In a multivariable model, the independent predictors of mortality at 1 year were ALC 1410 cells/μl or less at admission [hazard ratio 2.04; CI (confidence interval) 95% (1.06-3.95); P = 0.033], age [hazard ratio 1.08; CI 95% (1.04-1.12); P < 0.001], baseline serum creatinine [hazard ratio 1.25; CI 95% (1.05-1.50); P = 0.012] and baseline serum Na [hazard ratio 0.91; CI 95% (0.85-0.98); P = 0.013].

CONCLUSION

Low ALC in patients with AHF is associated with higher in-hospital mortality during the hospitalization and is an independent predictor of long-term mortality.

Combined use of lung ultrasound, B-type natriuretic peptide, and echocardiography for outcome prediction in patients with acute HFrEF and HFpEF

BACKGROUND

Lung ultrasound (LUS) can be used to assess pulmonary congestion by imaging B-lines ('comets') for patients with acute heart failure (AHF).

OBJECTIVES

Investigate relationship of B-lines, plasma concentrations of B-type natriuretic peptide (BNP), and echocardiographic left ventricular (LV) function measured at admission and discharge and their relationship to prognosis for AHF with preserved (HFpEF) or reduced (HFrEF) LV ejection fraction.

METHODS

Patients with AHF had the above tests done at admission and discharge. The primary outcome was re-hospitalization for heart failure or death at 6 months.

RESULTS

Of 162 patients enrolled, 95 had HFrEF and 67 had HFpEF, median age was 80 [77-85] years, and 85 (52%) were women. The number of B-lines at admission (median 31 [27-36]) correlated with respiratory rate (r = 0.75; p < 0.001), BNP (r = 0.43; p < 0.001), clinical congestion score (r = 0.25; p = 0.001), and systolic pulmonary artery pressure (r = 0.42; p < 0.001). At discharge, B-lines were also correlated with BNP (r = 0.69; p < 0.001) and congestion score (r = 0.57; p < 0.001). B-line count at discharge predicted outcome (AUC 0.83 [0.77-0.90]; univariate HR 1.12 [1.09-1.16]; p < 0.001; multivariable HR 1.16 [1.11-1.21]; p < 0.001). Results were similar for HFpEF and HFrEF.

CONCLUSIONS

LUS appears a useful method to assess severity and monitor the resolution of lung congestion. At hospital admission, B-lines are strongly related to respiratory rate, which may be a key component of the sensation of dyspnea. Measurement of lung congestion at discharge provides prognostic information for patients with either HFpEF or HFrEF.

Optimal course of treatment in acute cardiogenic shock complicating myocardial infarction

INTRODUCTION

About 5% of patients with myocardial infarction suffer from cardiogenic shock as a complication, with a mortality of ≥30%. Primary percutaneous coronary intervention as soon as possible is the most successful therapeutic approach. Prognosis depends not only on the extent of infarction, but also - and even more - on organ hypoperfusion with consequent development of multiple organ dysfunction syndrome. Areas covered: This review covers diagnostic, monitoring and treatment concepts relevant for caring patients with cardiogenic shock complicating myocardial infarction. All major clinical trials have been selected for review of the recent data. Expert commentary: For optimal care, not only primary percutaneous intervention of the occluded coronary artery is necessary, but also best intensive care medicine avoiding the development of multiple organ dysfunction syndrome and finally death. On contrary, intra-aortic balloon pump - though used for decades - is unable to reduce mortality of patients with cardiogenic shock complicating myocardial infarction.

Evaluation of Resting Cardiac Power Output as a Prognostic Factor in Patients with Advanced Heart Failure

If the heart is represented by a hydraulic pump, cardiac power represents the hydraulic function of the heart. Cardiac pump function is frequently determined through left ventricular ejection fraction using imaging. This study aims to validate resting cardiac power output (CPO) as a predictive biomarker in patients with advanced heart failure (HF). One hundred and seventy-two patients with HF severe enough to warrant cardiac transplantation were retrospectively reviewed at a single tertiary care institution between September 2010 and July 2013. Patients were initially evaluated with simultaneous right-sided and left-sided cardiac catheter-based hemodynamic measurements, followed by longitudinal follow-up (median of 52 months) for adverse events (cardiac mortality, cardiac transplantation, or ventricular assist device placement). Median resting CPO was 0.54 W (long rank chi-square = 33.6; p < 0.0001). Decreased resting CPO (<0.54 W) predicted increased risk for adverse outcomes. Fifty cardiac deaths, 10 cardiac transplants, and 12 ventricular assist device placements were documented. The prognostic relevance of resting CPO remained significant after adjustment for age, gender, left ventricular ejection fraction, mean arterial pressure, pulmonary vascular resistance, right atrial pressure, and estimated glomerular filtration rate (HR, 3.53; 95% confidence interval, 1.66 to 6.77; p = 0.0007). In conclusion, lower resting CPO supplies independent prediction of adverse outcomes. Thus, it could be effectively used for risk stratification in patients with advanced HF.

Inorganic nitrate as a treatment for acute heart failure: a protocol for a single center, randomized, double-blind, placebo-controlled pilot and feasibility study

Background

Acute heart failure (AHF) is a frequent reason for hospitalization worldwide and effective treatment options are limited. It is known that AHF is a condition characterized by impaired vasorelaxation, together with reduced nitric oxide (NO) bioavailability, an endogenous vasodilatory compound. Supplementation of inorganic sodium nitrate (NaNO₃) is an indirect dietary source of NO, through bioconversion. It is proposed that oral sodium nitrate will favorably affect levels of circulating NO precursors (nitrate and nitrite) in AHF patients, resulting in reduced systemic vascular resistance, without significant hypotension.

Methods and outcomes

We propose a single center, randomized, double-blind, placebo-controlled pilot trial, evaluating the feasibility of sodium nitrate as a treatment for AHF. The primary hypothesis that sodium nitrate treatment will result in increased systemic levels of nitric oxide pre-cursors (nitrate and nitrite) in plasma, in parallel with improved vasorelaxation, as assessed by non-invasively derived systemic vascular resistance index. Additional surrogate measures relevant to the known pathophysiology of AHF will be obtained in order to assess clinical effect on dyspnea and renal function.

Discussion

The results of this study will provide evidence of the feasibility of this novel approach and will be of interest to the heart failure community. This trial may inform a larger study.

Fatal Systemic Vasoconstriction in a Case of Metastatic Small-Intestinal NET

An increased release of serotonin secreted by ileal NETs is thought to be the major factor causing the carcinoid syndrome. However, in acutely arising carcinoid crisis also other vasoactive factors may lead to hazardous fluctuations in blood pressure and bronchial constriction. In rare cases, systemic vasoconstriction can be observed, probably caused by catecholamines or similar acting substances. Here, we report a fatal case of fulminant systemic vasoconstriction possibly caused by catecholamines in a patient with metastasized ileal NET. The vasospasm was detected by CT-angiography, and hemodynamic monitoring revealed a high systemic vascular resistance. Epinephrine, norepinephrine, and chromogranin A levels in plasma were elevated as was the urinary 5-hydroxyindoleacetic acid (5-HIAA). The cause of death was heart failure due to severe circulatory insufficiency. The progression of the tumor disease was confirmed by autopsy.

Cardiac remodeling following reperfused acute myocardial infarction is linked to the concomitant evolution of vascular function as assessed by cardiovascular magnetic resonance

BACKGROUND

Left ventricular (LV) remodeling following acute myocardial infarction (MI) is difficult to predict at an individual level although a possible interfering role of vascular function has yet to be considered to date. This study aimed to determine the extent to which this LV remodeling is influenced by the concomitant evolution of vascular function and LV loading conditions, as assessed by phase-contrast Cardiovascular Magnetic Resonance (CMR) of the ascending aorta.

METHODS

CMR was performed in 121 patients, 2-4 days after reperfusion of a first ST-segment elevation myocardial infarction and 6 months thereafter. LV remodeling was: (i) assessed by the 6-month increase in end-diastolic volume (EDV) and/or ejection fraction (EF) and (ii) correlated with the indexed aortic stroke volume (mL.m-2), determined by a CMR phase-contrast sequence, along with derived functional vascular parameters (total peripheral vascular resistance (TPVR), total arterial compliance index, effective arterial elastance).

RESULTS

At 6 months, most patients were under angiotensin enzyme converting inhibitors (86%) and beta-blockers (84%) and, on average, all functional vascular parameters were improved whereas blood pressure levels were not. An increase in EDV only (EDV+/EF-) was documented in 17% of patients at 6 months, in EF only (EDV-/EF+) in 31%, in both EDV and EF (EDV+/EF+) in 12% and neither EDV nor EF (EDV-/EF-) in 40%. The increase in EF was mainly and independently linked to a concomitant decline in TPVR (6-month change in mmHg.min.m2.L-1, EDV-/EF-: +1 ± 8, EDV+/EF-: +3 ± 9, EDV-/EF+: -7 ± 6, EDV+/EF+: -15 ± 20, p < 0.001) while the absence of any EF improvement was associated with high persisting rates of abnormally high TPVR at 6 months (EDV-/EF-: 31%, EDV+/EF-: 38%, EDV-/EF+: 5%, EDV+/EF+: 13%, p = 0.007). By contrast, the 6-month increase in EDV was mainly dependent on cardiac as opposed to vascular parameters and particularly on the presence of microvascular obstruction at baseline (EDV-/EF-: 37%, EDV+/EF-: 76%, EDV-/EF+: 38%, EDV+/EF+: 73%, p = 0.003).

CONCLUSION

LV remodeling following reperfused MI is strongly influenced by the variable decrease in systemic vascular resistance under standard care vasodilating medication. The CMR monitoring of vascular resistance may help to tailor these medications for improving vascular resistance and consequently, LV ejection fraction.

TRIAL REGISTRATION

NCT01109225 on ClinicalTrials.gov site (April, 2010).

Minimally invasive beat-by-beat monitoring of cardiac power in normal hearts and during acute ventricular dysfunction

Cardiac power, the product of aortic flow and blood pressure, appears to be a fundamental cardiovascular parameter. The simplified version named cardiac power output (CPO), calculated as the product of cardiac output (CO) in L/min and mean arterial pressure (MAP) in mmHg divided by 451, has shown great ability to predict outcome in a broad spectrum of cardiac disease. Beat‐by‐beat evaluation of cardiac power (PWR) therefore appears to be a possibly valuable addition when monitoring circulatory unstable patients, providing parameters of overall cardiovascular function. We have developed a minimally invasive system for cardiac power measurement, and aimed in this study to compare this system to an invasive method (ttPWR). Seven male anesthetized farm pigs were included. A laptop with in‐house software gathered audio from Doppler signals of aortic flow and blood pressure from the patient monitor to continuously calculate and display a minimally invasive cardiac power trace (uPWR). The time integral per cardiac cycle (uPWR‐integral) represents cardiac work, and was compared to the invasive counterpart (ttPWR‐integral). Signals were obtained at baseline, during mechanically manipulated preload and afterload, before and after induced global ischemic left ventricular dysfunction. We found that the uPWR‐integral overestimated compared to the ttPWR‐integral by about 10% (P < 0.001) in both normal hearts and during ventricular dysfunction. Bland–Altman limits of agreement were at +0.060 and −0.054 J, without increasing spread over the range. In conclusion we find that the minimally invasive system follows its invasive counterpart, and is ready for clinical research of cardiac power parameters.

The value of novel invasive hemodynamic parameters added to the TIMI risk score for short-term prognosis assessment in patients with ST segment elevation myocardial infarction

BACKGROUND

We compared the prognostic capacity of conventional and novel invasive parameters derived from the slope of the preload recruitable stroke work relationship (PRSW) in STEMI patients and assessed their contribution to the TIMI risk score.

METHODS

Left ventricular end-diastolic pressure (EDP), ejection fraction (EF), pressure adjusted maximum rate of pressure change in the left ventricle (dP/dt/P), aortic systolic pressure to EDP ratio (SBP/EDP) and end-diastolic volume adjusted stroke work (EW), derived from the slope of the PRSW relationship, were obtained during the emergency cardiac catheterization in 523 STEMI patients. The predictive power of the analyzed parameters for 30-day and 1-year mortality was evaluated using C-statistics and reclassification analysis was adopted to assess the improvement in TIMI score.

RESULTS

The highest area under the curve (AUC) values for 30-day mortality were observed for EW (0.872(95% confidence interval 0.801-0.943)), SBP/EDP (0.843(0.758-0.928)) and EF (0.833(0.735-0.931)); p<0.001 for all values. For 1-year mortality the best predictive value was found for EW (0.806(0.724-0.887) and EF (0.793(0.703-0.883)); p<0.001 for both. The addition of EDP, SBP/EDP ratio and EW to TIMI score significantly increased the AUC according to De Long's test. For 30-day mortality, increased discriminative power following addition to the TIMI score was observed for EW and SBP/EDP (Integrated Discrimination Improvement was 0.086(0.033-0.140), p=0.002 and 0.078(0.028-0.128), p=0.002, respectively).

CONCLUSIONS

EW and SBP/EDP are prognostic markers with high predictive value for 30-day and 1-year mortality. Both parameters, easily obtained during emergency catheterization, improve the discriminatory capacity of the TIMI score for 30-day mortality.

Comparison of Estimations Versus Measured Oxygen Consumption at Rest in Patients With Heart Failure and Reduced Ejection Fraction Who Underwent Right-Sided Heart Catheterization

Cardiac output during right-sided heart catheterization is an important variable for patient selection of advanced therapies (cardiac transplantation and left ventricular assist device implantation). The Fick method to determine cardiac output is commonly used and typically uses estimated oxygen consumption (VO2) from 1 of 3 published empirical formulas. However, these estimation equations have not been validated in patients with heart failure and reduced ejection fraction (HFrEF). The objectives of the present study were to determine the accuracy of 3 equations for estimating VO2 compared with direct measurement of VO2 and determine the extent clinically significant error occurred in calculating cardiac output of patients with HFrEF. Breath-by-breath measurements of VO2 from 44 patients who underwent cardiac catheterization (66% men; age, 65 ± 11 years, left ventricular ejection fraction, 22 ± 6%) were compared with the derived estimations of LaFarge and Miettinen, Dehmer et al, and Bergstra et al. Single-sample t tests found only the mean difference between the estimation of LaFarge and Miettinen and the measured VO2 to be nonsignificant (-10.3 ml/min ± 6.2 SE, p = 0.053). Bland-Altman plots demonstrated unacceptably large limits of agreement for all equations. The rate of ≥25% error in the equations by LaFarge and Miettinen, Dehmer et al, and Bergstra et al occurred in 11%, 23%, and 45% of patients, respectively. Misclassification of cardiac index derived from each equation for 2 clinically important classifications: cardiogenic shock-21%, 23%, and 32% and hypoperfusion-16%, 16%, and 25%; respectively. In conclusion, these findings do not support the use of these empiric formulas to estimate the VO2 at rest in patients with HFrEF who underwent right-sided heart catheterization.

Impaired cardiac and peripheral hemodynamic responses to inhaled β₂-agonist in cystic fibrosis

Background

Pulmonary system dysfunction is a hallmark of cystic fibrosis (CF) disease. In addition to impaired cystic fibrosis transmembrane conductance regulator protein, dysfunctional β₂-adrenergic receptors (β₂AR) contribute to low airway function in CF. Recent observations suggest CF may also be associated with impaired cardiac function that is demonstrated by attenuated cardiac output (Q), stroke volume (SV), and cardiac power (CP) at both rest and during exercise. However, β₂AR regulation of cardiac and peripheral vascular tissue, in-vivo, is unknown in CF. We have previously demonstrated that the administration of an inhaled β-agonist increases SV and Q while also decreasing SVR in healthy individuals. Therefore, we aimed to assess cardiac and peripheral hemodynamic responses to the selective β₂AR agonist albuterol in individuals with CF.

Methods

18 CF and 30 control (CTL) subjects participated (ages 22 ± 2 versus 27 ± 2 and BSA = 1.7 ± 0.1 versus 1.8 ± 0.0 m², both p < 0.05). We assessed the following at baseline and at 30- and 60-minutes following nebulized albuterol (2.5mg diluted in 3.0mL of normal saline) inhalation: 12-lead ECG for HR, manual sphygmomanometry for systolic and diastolic blood pressure (SBP and DBP, respectively), acetylene rebreathe for Q and SV. We calculated MAP = DBP + 1/3(SBP–DBP); systemic vascular resistance (SVR) = (MAP/Q)•80; CP = Q•MAP; stroke work (SW) = SV•MAP; reserve (%change baseline to 30- or 60-minutes). Hemodynamics were indexed to BSA (Q_I, SV_I, SW_I, CP_I, SVR_I).

Results

At baseline, CF demonstrated lower SV, SV_I, SW, and SW_I but higher HR than CTL (p < 0.05); other measures did not differ. At 30-minutes, CF demonstrated higher HR and SVR_I, but lower Q, SV, SV_I, CP, CP_I, SW, and SW_I versus CTL (p < 0.05). At 60-minutes, CF demonstrated higher HR, SVR, and SVR_I, whereas all cardiac hemodynamics were lower than CTL (p < 0.05). Reserves of CP, SW, and SVR were lower in CF versus CTL at both 30 and 60-minutes (p < 0.05).

Conclusions

Cardiac and peripheral hemodynamic responsiveness to acute β₂AR stimulation via albuterol is attenuated in individuals with CF, suggesting β₂AR located in cardiac and peripheral vascular tissue may be dysfunctional in this population.

Prognostic role of cardiac power index in ambulatory patients with advanced heart failure

BACKGROUND

Cardiac pump function is often quantified by left ventricular ejection fraction by various imaging modalities. As the heart is commonly conceptualized as a hydraulic pump, cardiac power describes the hydraulic function of the heart. We aim to describe the prognostic value of resting cardiac power index (CPI) in ambulatory patients with advanced heart failure.

METHODS AND RESULTS

We calculated CPI in 495 sequential ambulatory patients with advanced heart failure who underwent invasive haemodynamic assessment with longitudinal follow-up of adverse outcomes (all-cause mortality, cardiac transplantation, or ventricular assist device placement). The median CPI was 0.44 W/m(2) (interquartile range 0.37, 0.52). Over a median of 3.3 years, there were 117 deaths, 104 transplants, and 20 ventricular assist device placements in our cohort. Diminished CPI (<0.44 W/m(2) ) was associated with increased adverse outcomes [hazard ratio (HR) 2.4, 95% confidence interval (CI) 1.8-3.1, P < 0.0001). The prognostic value of CPI remained significant after adjustment for age, gender, pulmonary capillary wedge pressure, cardiac index, pulmonary vascular resistance, left ventricular ejection fraction, and creatinine [HR 1.5, 95% CI 1.03-2.3, P = 0.04). Furthermore, CPI can risk stratify independently of peak oxygen consumption (HR 2.2, 95% CI 1.4-3.4, P = 0.0003).

CONCLUSION

Resting cardiac power index provides independent and incremental prediction in adverse outcomes beyond traditional haemodynamic and cardio-renal risk factors.

The vital role of the right ventricle in the pathogenesis of acute pulmonary edema

The development of acute pulmonary edema involves a complex interplay between the capillary hydrostatic, interstitial hydrostatic, and oncotic pressures and the capillary permeability. We review the pathophysiological processes involved and illustrate the concepts in a number of common clinical situations including heart failure with normal and reduced ejection fractions, mitral regurgitation, and arrhythmias. We also describe other rarer causes including exercise, swimming, and diving-induced acute pulmonary edema. We suggest a unifying framework in which the critical abnormality is a mismatch or imbalance between the right and left ventricular stroke volumes. In conclusion, we hypothesize that increased right ventricular contraction is an important contributor to the sudden increase in capillary hydrostatic pressure, and therefore, a central mechanism involved in the development of alveolar edema.