Noninvasive measurement of systemic vascular resistance using Doppler echocardiography

New perspectives in the echocardiographic hemodynamics multiparametric assessment of patients with heart failure

International Guidelines consider left ventricular ejection fraction (LVEF) as an important parameter to categorize patients with heart failure (HF) and to define recommended treatments in clinical practice. However, LVEF has some technical and clinical limitations, being derived from geometric assumptions and is unable to evaluate intrinsic myocardial function and LV filling pressure (LVFP). Moreover, it has been shown to fail to predict clinical outcome in patients with end-stage HF. The analysis of LV antegrade flow derived from pulsed-wave Doppler (stroke volume index, stroke distance, cardiac output, and cardiac index) and non-invasive evaluation of LVFP have demonstrated some advantages and prognostic implications in HF patients. Speckle tracking echocardiography (STE) is able to unmask intrinsic myocardial systolic dysfunction in HF patients, particularly in those with LV preserved EF, hence allowing analysis of LV, right ventricular and left atrial (LA) intrinsic myocardial function (global peak atrial LS, (PALS)). Global PALS has been proven a reliable index of LVFP which could fill the gaps "gray zone" in the previous Guidelines algorithm for the assessment of LV diastolic dysfunction and LVFP, being added to the latest European Association of Cardiovascular Imaging Consensus document for the use of multimodality imaging in evaluating HFpEF. The aim of this review is to highlight the importance of the hemodynamics multiparametric approach of assessing myocardial function (from LVFP to stroke volume) in patients with HF, thus overcoming the limitations of LVEF.

Systemic vascular resistance predicts high-output cardiac failure in patients with high-flow arteriovenous fistula

AIMS

Patients with high-flow arteriovenous (AV) access are at risk of developing high-output cardiac failure (HOCF) and subsequent hospitalization. However, diagnosing HOCF is challenging and often requires invasive procedures. The role of systemic vascular resistance (SVR) in diagnosing HOCF is underestimated, and its predictive value is limited. Our study aims to identify non-invasive risk factors for HOCF to facilitate early diagnosis and timely surgical interventions.

METHODS AND RESULTS

We included 109 patients with high-flow AV access who underwent serial echocardiography. The retrospective cohort was divided into two groups based on their hospitalization due to HOCF. The two groups were matched for age and gender. After a mean follow-up of 25.1 months, 19 patients (17.4%) were hospitalized due to HOCF. The two groups had similar baseline characteristics. However, the HOCF group had a higher value of vascular access blood flow (Qa) (2168 ± 856 vs. 1828 ± 617 mL/min; P = 0.045). Echocardiographic analysis revealed that the HOCF group had more pronounced left ventricular diastolic dysfunction (E/e': 21.1 ± 7.3 vs. 16.2 ± 5.9; P = 0.002), more severe pulmonary hypertension (right ventricular systolic pressure: 41.4 ± 16.7 vs. 32.2 ± 12.8; P = 0.009), a higher Doppler-derived cardiac index (CI) (4.3 ± 0.8 vs. 3.7 ± 1.1; P = 0.031), and a lower Doppler-derived estimated SVR (eSVR) value (5.5 ± 0.3 vs. 6.9 ± 0.2; P = 0.002) than the non-HOCF group. Using multivariable Cox regression analysis, a low eSVR value (<6) emerged as an independent predictor of HOCF hospitalization with a hazard ratio of 9.084 (95% confidence interval, 2.33-35.39; P = 0.001). Receiver operating characteristic curve analysis indicated that CI/eSVR values more accurately predicted HOCF hospitalization [sensitivity: 94.7%, specificity: 51.0%, area under the curve (AUC): 0.75, P < 0.001] than the Qa/cardiac output ratio (AUC: 0.50, P = 0.955), Qa values ≥ 2000 mL/min (AUC: 0.60, P = 0.181), and Qa values indexed for height in metres (AUC: 0.65, P = 0.040).

CONCLUSIONS

In patients with high-flow AV access, low eSVR values obtained through non-invasive Doppler echocardiography were associated with a high rate of HOCF hospitalizations. Therefore, routine eSVR screening in these patients might expedite the diagnosis of HOCF.

A novel echocardiographic estimate of pulmonary vascular resistance employing the hydraulic analogy to Ohm’s law

Background

Assessment of pulmonary vascular resistance (PVR) is critical for accurate diagnosis and optimal pharmacotherapy in pulmonary hypertension. We aimed to test the diagnostic performance of a novel, Doppler-based method to evaluate PVR based on Ohm’s law (PVR_echo) using pragmatic estimates of pulmonary capillary wedge pressure (PCWP).

Methods and results

Simultaneous right heart catheterization (RHC) and echocardiography was performed in a derivation cohort of 111 patients in sinus rhythm referred for PH evaluation and PVR_echo independently validated in 238 patients. PVR_echo was calculated using pulmonary artery mean pressure estimates (PAMP_echo) obtained from peak tricuspid gradient employing a fixed right atrial pressure estimate, PCWP_echo was estimated as 10 or 20 mmHg using age-related mitral E/A cut-offs and cardiac output from left ventricular outflow. In the derivation cohort, both PAMP_echo and PCWP_echo estimates demonstrated excellent agreement with catheterization measurements. PVR_echo was highly feasible, demonstrated negligible bias and excellent agreement with PVR_RHC (Bias = −0.58, SD 2.2 mmHg) and outperformed the Abbas method to identify PVR_RHC > 3WU (AUC = 0.85 vs. 0.70; p = 0.02). In the validation cohort, PVR_echo preserved good invasive agreement with negligible bias, displayed strong diagnostic performance (AUC = 0.84) and significant ability to distinguish isolated post-capillary from combined post- and pre-capillary pulmonary hypertension (PH) subgroups (AUC = 0.77).

Conclusion

PVR_echo based on Ohm’s law employing pragmatic estimates of PCWP_echo demonstrates excellent agreement with invasive reference standard measurements and strong diagnostic ability to identify elevated PVR_RHC. This novel approach may be useful during therapy selection to distinguish PH hemodynamic subgroups.

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.

A new physiologic-based integrated algorithm in the management of neonatal hemodynamic instability

Physiologic-based management of hemodynamic instability is proven to guide the logical selection of cardiovascular support and shorten the time to clinical recovery compared to an empiric approach that ignores the heterogeneity of the hemodynamic instability related mechanisms. In this report, we classified neonatal hemodynamic instability, circulatory shock, and degree of compensation into five physiologic categories, based on different phenotypes of blood pressure (BP), other clinical parameters, echocardiography markers, and oxygen indices. This approach is focused on hemodynamic instability in infants with normal cardiac anatomy.Conclusion: The management of hemodynamic instability is challenging due to the complexity of the pathophysiology; integrating different monitoring techniques is essential to understand the underlying pathophysiologic mechanisms and formulate a physiologic-based medical recommendation and approach. What is Known: • Physiologic-based assessment of hemodynamics leads to targeted and pathophysiologic-based medical recommendations. What is New: • Hemodynamic instability in neonates can be categorized according to the underlying mechanism into five main categories, based on blood pressure phenotypes, systemic vascular resistance, and myocardial performance. • The new classification helps with the targeted management and logical selection of cardiovascular support.

Use of Cardiac Imaging to Evaluate Cardiac Function and Pulmonary Hemodynamics in Patients with Heart Failure

PURPOSE OF REVIEW

Noninvasive hemodynamic assessments in patients with heart failure (HF) are essential for appropriate diagnosis and establishment of the best treatment strategies. Recently, the impact of pulmonary circulation and right ventricular function on prognosis in HF patients has drawn increasing attention. In this article, we explore the usefulness of cardiac imaging for hemodynamic assessments, mainly focusing on echocardiographic evaluation.

RECENT FINDINGS

The reliability of Doppler echocardiography as a noninvasive alternative to Swan-Ganz catheterization has been well investigated with higher than 80% accuracy for estimating pulmonary artery pressure. Strain measurement and three-dimensional echocardiography are useful for evaluating right ventricular function together with pulmonary circulation. The accuracy of analyzing left and right ventricular functions by cardiac computed tomography and cardiac magnetic resonate imaging has also been established. These modalities can provide myocardial tissue information and allow calculation of the extracellular volume fraction as well. According to the rapid improvement of technologies, cardiac imaging has become an essential tool for hemodynamic evaluation in HF management.

Predictive value of P-wave and QT interval dispersion in children with congenital heart disease and pulmonary arterial hypertension for the occurrence of arrhythmias

OBJECTIVES

To evaluate P-wave dispersion (PWD) and QT dispersion (QTd) in children with congenital heart disease and pulmonary arterial hypertension (PAH-CHD) and to investigate the predictive value of both PWD and QTd for prediction of arrhythmias in such children.

MATERIALS AND METHODS

We included 40 children with PAH-CHD as Group I. Forty other children with CHD and no PAH were included as Group II. Forty healthy children of matched age and sex served as a Control group. Electrocardiography was performed to determine PWD and QTd. Furthermore, 24-hour Holter monitoring was performed to detect the presence of arrhythmias. Echocardiographic evaluation was also performed.

RESULTS

QTd and PWD were significantly higher in Group I than in Group II and Control group. A significant positive correlation was present between both QTd and PWD and mean pulmonary artery pressure, right ventricular diameter, pulmonary vascular resistance (PVR), and PVR to systemic vascular resistance ratio. QTd showed 93% sensitivity, 80% specificity, and 85% accuracy for prediction of occurrence of arrhythmias in patients with PAH-CHD at a cutoff point of 61 ms, whereas PWD showed 87% sensitivity, 80% specificity, and 85% accuracy for prediction of arrhythmias at a cutoff point of 32.5 ms in such patients. Logistic regression analysis showed that both QTd and PWD were good predictors for the occurrence of arrhythmias in children with PAH-CHD (p = 0.003 and p = 0.01, respectively).

CONCLUSIONS

PWD and QTd were good predictors for the occurrence of various arrhythmias in children with PAH-CHD.

Impact of hyponatremia on frequency of complications in patients with decompensated liver cirrhosis

Introduction

Hyponatremia is common in cirrhosis. The relationship between hyponatremia and severity of cirrhosis is evidenced by its close association with the occurrence of complications, the prevalence of hepatic encephalopathy, hepatorenal syndrome, spontaneous bacterial peritonitis, refectory ascites, and hepatic hydrothorax. The aim of this study was assess the impact of hyponatremia on the occurrence of both liver-related complications and the hemodynamic cardiovascular dysfunction.

Methods

This prospective study was conducted in 2015 on 74 patients with liver cirrhosis. The patients were from the Gastroenterology and Hepatology Department of Theodor Bilharz Research Institute in Giza, Egypt. The patients were divided into three groups according to their serum level of sodium. Group 1 included 30 patients with serum sodium >135 meq/L, group 2 included 24 patients with serum sodium between135 and 125 meq/L, and group 3 included 20 patients with serum sodium <125 meq/L. For each of the patients, we conducted aclinical examination, laboratory investigations, chest X-ray, ECG, abdominal sonar, and echocardiography.

Results

Hyponatremia was found in 59.46% of our cirrhotic patients, and they showed significantly increased Model for End-Stage Liver Disease (MELD) score, MELD-Na score, QTc interval, Pulmonary vascular resistance (PVR) and inferior vena cava (IVC) collapsibility, and decreased SVR and IVC diameter. Also hepatic encephalopathy, ascites, renal failure, infectious complications, and pleural effusion were significantly more common in hyponatremic cirrhotic patients.

Conclusion

In cirrhosis, hyponatremia is more common in severe cardiovascular dysfunction and associated with increased risk of hepatic encephalopathy, ascites, illness severity scores, renal failure, infectious complications, and pleural effusion. We recommend selective oral administration of vasopressin V2-receptor antagonist, tolvaptan, which acts to increase the excretion of free water, thereby resolving hypervolemic hyponatremia and may have the potential to improve outcomes in these patients.

Systemic vascular resistance and fluid status in patients with decompensated liver cirrhosis with or without functional renal failure in Egypt

BACKGROUND

Functional renal failure and cardiovascular dysfunction are common complications of liver cirrhosis. This study aimed to evaluate cardiac performance, systemic vascular resistance (SVR) and fluid status in patients with decompensated liver cirrhosis either with or without functional renal failure.

METHODS

Sixty patients diagnosed as having decompensated liver cirrhosis were divided into two groups. Group 1 included 30 patients with decompensated liver cirrhosis with ascites and with creatinine values ≤ 1.5 mg/dl. Group 2 included 30 azotemic decompensated cirrhotic patients with diagnostic criteria of hepatorenal syndrome (HRS). Also, 20 healthy subjects, of matched age and sex to the Group 1 and Group 2 patients, were included in the study as the control group. All patients and normal controls were subjected to clinical examination, laboratory evaluation, ECG, abdominal ultrasonography and echocardiographic studies.

RESULTS

The echocardiographic and ECG data showed significant increase in LAD (P<0.01, P<0.01), AoD (P<0.05, P<0.01), interventricular septum thickness (IVST) (P<0.01, P<0.01), posterior wall thickness (PWT) (P<0.01, P<0.01), EDD (P<0.01, P<0.01), ESD (P<0.05, P<0.01), left ventricular (LV) mass (P<0.01, P<0.01), and Corrected QT (QTc) (P<0.01, P<0.01) interval with significant decrease in SVR (P<0.01, P<0.01). Additionally, there was significant decrease in IVC diameter in both patients groups compared to the control group (P<0.01, P<0.01).

CONCLUSION

Patients with decompensated liver cirrhosis have low SVR, and Doppler echocardiography provides an easy noninvasive tool to assess this finding. Also, these patients demonstrate small inferior vena cava (IVC) diameter with normal collapsibility, which indicates low effective plasma volume. Measuring IVC diameter and collapsibility are of value in the prediction of intravascular fluid status in liver cirrhosis. This is especially true with renal dysfunction. Early addition of oral vasoconstrictors in decompensated patients may correct the SVR and circulatory dysfunction and hinder HRS occurrence.

Impact of afterload on the assessment of severity of aortic stenosis

BACKGROUND

Aortic stenosis (AS) is increasingly diagnosed in current aging society. Echocardiography is the most important tool in the assessment of AS and its severity. However, load-dependency of Doppler measurement could affect the accuracy of AS severity assessment. We tried to evaluate the impact of afterload on the assessment of AS severity by modification of afterload using pneumatic compression (Pcom).

METHODS

Forty patients diagnosed as moderate or severe AS [effective orifice area of aortic valve (EOA_AV) by continuity equation of < 1.5 cm²] were consecutively enrolled. Patients with severely uncontrolled hypertension, severe left ventricular (LV) dysfunction, and other significant valve disease were excluded. Comprehensive echocardiography was performed at baseline to assess AS severity. Then, pneumatic compression of the lower extremities by 100 mmHg was applied to increase LV afterload. After 3 minutes, echocardiography was repeated to assess AS severity.

RESULTS

Mean blood pressure was significantly increased under Pcom (p < 0.001), while heart rate remained unchanged. Peak aortic valve velocity (V_max) was slightly, but significantly decreased under Pcom (p = 0.03). However, Doppler velocity index and EOA_AV by continuity equation were not affected by Pcom.

CONCLUSION

AS severity assessment by echocardiography was not dependent on the change of LV afterload imposed by Pcom. AV V_max was slightly decreased with LV afterload increment, but these changes were too small to alter treatment plan of AS patients. EOA_AV and Doppler velocity index are more stable parameters for AS severity assessment.

Local and systemic cardiovascular effects from monochromatic infrared therapy in patients with knee osteoarthritis: a double-blind, randomized, placebo-controlled study

Infrared (IR) therapy is used for pain relief in patients with knee osteoarthritis (OA). However, IR's effects on the cardiovascular system remain uncertain. Therefore, we investigated the local and systemic cardiovascular effects of monochromatic IR therapy on patients with knee OA in a double-blind, randomized, placebo-controlled study. Seventy-one subjects with knee OA received one session of 40 min of active or placebo monochromatic IR treatment (with power output of 6.24 W, wavelength of 890 nm, power density of 34.7 mW/cm² for 40 min, total energy of 41.6 J/cm² per knee per session) over the knee joints. Heart rate, blood pressure, and knee arterial blood flow velocity were periodically assessed at the baseline, during, and after treatment. Data were analyzed by repeated-measure analysis of covariance. Compared to baseline, there were no statistically significant group x time interaction effects between the 2 groups for heart rate (P = 0.160), blood pressure (systolic blood pressure: P = 0.861; diastolic blood pressure: P = 0.757), or mean arterial blood flow velocity (P = 0.769) in follow-up assessments. The present study revealed that although there was no increase of knee arterial blood flow velocity, monochromatic IR therapy produced no detrimental systemic cardiovascular effects.

[Evaluation of contractility and postloading in the intensive care unit]

Cardiovascular failure is a common disorder in critical care medicine. When admitted to the ICU, patients with hemodynamic deterioration should be examined rapidly to correctly assess the main determinants of cardiovascular function (preload, afterload and contractility). This review examines the assessment of contractility and afterload involving the combined use of several hemodynamic monitors, which allows different approaches to the same problem, with a view to improving the efficiency of management and treatment in critically ill patients.

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.

Echocardiography practice, training and accreditation in the intensive care: document for the World Interactive Network Focused on Critical Ultrasound (WINFOCUS)

Echocardiography is increasingly used in the management of the critically ill patient as a non-invasive diagnostic and monitoring tool. Whilst in few countries specialized national training schemes for intensive care unit (ICU) echocardiography have been developed, specific guidelines for ICU physicians wishing to incorporate echocardiography into their clinical practice are lacking. Further, existing echocardiography accreditation does not reflect the requirements of the ICU practitioner. The WINFOCUS (World Interactive Network Focused On Critical UltraSound) ECHO-ICU Group drew up a document aimed at providing guidance to individual physicians, trainers and the relevant societies of the requirements for the development of skills in echocardiography in the ICU setting. The document is based on recommendations published by the Royal College of Radiologists, British Society of Echocardiography, European Association of Echocardiography and American Society of Echocardiography, together with international input from established practitioners of ICU echocardiography. The recommendations contained in this document are concerned with theoretical basis of ultrasonography, the practical aspects of building an ICU-based echocardiography service as well as the key components of standard adult TTE and TEE studies to be performed on the ICU. Specific issues regarding echocardiography in different ICU clinical scenarios are then described. Obtaining competence in ICU echocardiography may be achieved in different ways - either through completion of an appropriate fellowship/training scheme, or, where not available, via a staged approach designed to train the practitioner to a level at which they can achieve accreditation. Here, peri-resuscitation focused echocardiography represents the entry level--obtainable through established courses followed by mentored practice. Next, a competence-based modular training programme is proposed: theoretical elements delivered through blended-learning and practical elements acquired in parallel through proctored practice. These all linked with existing national/international echocardiography courses. When completed, it is anticipated that the practitioner will have performed the prerequisite number of studies, and achieved the competency to undertake accreditation (leading to Level 2 competence) via a recognized National or European examination and provide the appropriate required evidence of competency (logbook). Thus, even where appropriate fellowships are not available, with support from the relevant echocardiography bodies, training and subsequently accreditation in ICU echocardiography becomes achievable within the existing framework of current critical care and cardiological practice, and is adaptable to each countrie's needs.