Reference ranges and determinants of right ventricle outflow tract acceleration time in healthy adults by two-dimensional echocardiography

Prevalence of pulmonary hypertension in COPD patients living at high altitude

BACKGROUND

Pulmonary hypertension (PH) is associated with poor prognosis for patients with chronic obstructive pulmonary disease (COPD). Most of the knowledge about PH in COPD has been generated at sea level, with limited information associated with high altitude (HA).

OBJECTIVES

To assess the prevalence and severity of PH in COPD patients living in a HA city (2,640 m).

METHODS

Cross-sectional study in COPD patients with forced expiratory volume in the first second / forced vital capacity ratio (FEV1/FVC) post-bronchodilator <0,7. Transthoracic echocardiography (TTE), spirometry, carbon monoxide diffusing capacity, and arterial blood gasses tests were performed. Patients were classified according to the severity of airflow limitation. PH was defined by TTE as an estimated systolic pulmonary artery pressure (sPAP) > 36 mmHg or indirect PH signs; severe PH as sPAP > 60 mmHg; and disproportionate PH as an sPAP > 60 mmHg with non-severe airflow limitation (FEV1 > 50% predicted).

RESULTS

We included 176 COPD patients. The overall estimated prevalence of PH was 56.3% and the likelihood of having PH increased according to airflow-limitation severity: mild (31.6%), moderate (54.9%), severe (59.6%) and very severe (77.8%) (p = 0.038). The PH was severe in 7.3% and disproportionate in 3.4% of patients.

CONCLUSIONS

The estimated prevalence of PH in patients with COPD at HA is high, particularly in patients with mild to moderate airflow limitation, and greater than that described for COPD patients at low altitude. These results suggest a higher risk of developing PH for COPD patients living at HA compared to COPD patients with similar airflow limitation living at low altitude.

Exercise Stress Echocardiography of the Right Ventricle and Pulmonary Circulation

BACKGROUND

Exercise echocardiography is used for assessment of pulmonary circulation and right ventricular function, but limits of normal and disease-specific changes remain insufficiently established.

OBJECTIVES

The objective of this study was to explore the physiological vs pathologic response of the right ventricle and pulmonary circulation to exercise.

METHODS

A total of 2,228 subjects were enrolled: 375 healthy controls, 40 athletes, 516 patients with cardiovascular risk factors, 17 with pulmonary arterial hypertension, 872 with connective tissue diseases without overt pulmonary hypertension, 113 with left-sided heart disease, 30 with lung disease, and 265 with chronic exposure to high altitude. All subjects underwent resting and exercise echocardiography on a semirecumbent cycle ergometer. All-cause mortality was recorded at follow-up.

RESULTS

The 5th and 95th percentile of the mean pulmonary artery pressure-cardiac output relationships were 0.2 to 3.5 mm Hg.min/L in healthy subjects without cardiovascular risk factors, and were increased in all patient categories and in high altitude residents. The 5th and 95th percentile of the tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio at rest were 0.7 to 2.0 mm/mm Hg at rest and 0.5 to 1.5 mm/mm Hg at peak exercise, and were decreased at rest and exercise in all disease categories and in high-altitude residents. An increased all-cause mortality was predicted by a resting tricuspid annular plane systolic excursion to systolic pulmonary artery pressure <0.7 mm/mm Hg and mean pulmonary artery pressure-cardiac output >5 mm Hg.min/L.

CONCLUSIONS

Exercise echocardiography of the pulmonary circulation and the right ventricle discloses prognostically relevant differences between healthy subjects, athletes, high-altitude residents, and patients with various cardio-respiratory conditions. (Right Heart International NETwork During Exercise in Different Clinical Conditions; NCT03041337).

What echocardiographic findings differentiate acute pulmonary embolism and chronic pulmonary hypertension?

BACKGROUND

Pulmonary embolism (PE) and pulmonary hypertension (PH) are potentially fatal disease states. Early diagnosis and goal-directed management improve outcomes and survival. Both conditions share several echocardiographic findings of right ventricular dysfunction. This can inadvertently lead to incorrect diagnosis, inappropriate and potentially harmful management, and delay in time-sensitive therapies. Fortunately, bedside echocardiography imparts a few critical distinctions.

OBJECTIVE

This narrative review describes eight physiologically interdependent echocardiographic parameters that help distinguish acute PE and chronic PH. The manuscript details each finding along with associated pathophysiology and summarization of the literature evaluating diagnostic utility. This guide then provides pearls and pitfalls with high-quality media for the bedside evaluation.

DISCUSSION

The echocardiographic parameters suggesting acute or chronic right ventricular dysfunction (best used in combination) are: 1. Right heart thrombus (acute PE) 2. Right ventricular free wall thickness (acute ≤ 5 mm, chronic > 5 mm) 3. Tricuspid regurgitation pressure gradient (acute ≤ 46 mmHg, chronic > 46 mmHg, corresponding to tricuspid regurgitation maximal velocity ≤ 3.4 m/sec and > 3.4 m/sec, respectively) 4. Pulmonary artery acceleration time (acute ≤ 60-80 msec, chronic < 105 msec) 5. 60/60 sign (acute) 6. Pulmonary artery early-systolic notching (proximally-located, higher-risk PE) 7. McConnell's sign (acute) 8. Right atrial enlargement (equal to left atrial size suggests acute, greater than left atrial size suggests chronic).

CONCLUSIONS

Emergency physicians must appreciate the echocardiographic findings and associated pathophysiology that help distinguish acute and chronic right ventricular dysfunction. In the proper clinical context, these findings can point towards PE or PH, thereby leading to earlier goal-directed management.

PATET ratio by Doppler echocardiography: noninvasive detection of pediatric pulmonary arterial hypertension

Pulmonary artery acceleration time (PAT) and PAT: ejection time (PATET) ratio are echocardiographic measurements of pulmonary arterial hypertension (PAH). These noninvasive quantitative measurements are ideal to follow longitudinally through the clinical course of PAH, especially as it relates to the need for and/or response to treatment. This review article focuses on the current literature of PATET measurement for infants and children as it relates to the shortening of the PATET ratio in PAH. At the same time, further development of PATET as an outcome measure for PAH in preclinical models, particularly mice, such that the field can move forward to human clinical studies that are both safe and effective. Here, we present what is known about PATET in infants and children and discuss what is known in preclinical models with particular emphasis on neonatal mouse models. In both animal models and human disease, PATET allows for longitudinal measurements in the same individual, leading to more precise determinations of disease/model progression and/or response to therapy. IMPACT: PATET ratio is a quantitative measurement by a noninvasive technique, Doppler echocardiography, providing clinicians a more precise/accurate, safe, and longitudinal assessment of pediatric PAH. We present a brief history/state of the art of PATET ratio to predict PAH in adults, children, infants, and fetuses, as well as in small animal models of PAH. In a preliminary study, PATET shortened by 18% during acute hypoxic exposure compared to pre-hypoxia. Studies are needed to establish PATET, especially in mouse models of disease, such as bronchopulmonary, as a routine measure of PAH.

Physiologic Range of Myocardial Mechano-Energetic Efficiency among Healthy Subjects: Impact of Gender and Age

BACKGROUND

Myocardial mechano-energetic efficiency (MEE) is the capability of the left ventricle (LV) to convert the chemical energy obtained from the cardiac oxidative metabolism into mechanical work. The aim of present study was to establish normal non-invasive MEE and MEEi reference values.

METHODS

In total, 1168 healthy subjects underwent physical examinations, clinical assessment, and standardized transthoracic echocardiographic (TTE) examination. MEE was obtained by TTE as the ratio between stroke volume (SV) and heart rate (HR): MEE = SV/HR [HR expressed in seconds (HR/60)]. Because MEE is highly related to left ventricular mass (LVM), MEE was then divided by LVM with the purpose of obtaining an estimate of energetic expenditure per unit of myocardial mass (i.e., indexed MEE, MEEi, mL/s/g).

RESULTS

The mean values of MEE and MEEi in the overall population were 61.09 ± 18.19 mL/s; 0.45 ± 0.14, respectively. In a multivariable analysis, gender, body surface area (BSA), diastolic blood pressure, left atrial volume indexed to BSA, E/e' and tricuspid annular plane systolic excursion (TAPSE) were the independent variables associated with MEE, while age, gender, BSA and TAPSE were the independent variables associated with MEEi.

CONCLUSIONS

The knowledge of age- and gender-based MEE and MEEi normal values may improve the global assessment of LV cardiac mechanics and serve as a reference to identify phenotypes at high risk of cardiovascular events.

Pertussis Toxin Promotes Pulmonary Hypertension in an Infant Mouse Model of Bordetella pertussis Infection

Pertussis, caused by Bordetella pertussis, is a reemerging disease that can produce severe disease manifestations in infants, including pulmonary hypertension (PH). B. pertussis-induced PH is a major risk factor for infection-induced death, but the molecular mechanisms promoting PH are unknown and there is no effective treatment. We examined B. pertussis-induced PH in infant and adult mouse models of pertussis by Fulton index, right heart catheterization, or Doppler echocardiogram. Our results demonstrate that B. pertussis-induced PH is age related and dependent on the expression of pertussis toxin by the bacterium. Hence, pertussis toxin-targeting treatments may ameliorate PH and fatal infant infection.

Feasibility of semi-recumbent bicycle exercise Doppler echocardiography for the evaluation of the right heart and pulmonary circulation unit in different clinical conditions: the RIGHT heart international NETwork (RIGHT-NET)

Exercise Doppler echocardiography (EDE) is a well-validated tool in ischemic and valvular heart diseases. However, its use in the assessment of the right heart and pulmonary circulation unit (RH-PCU) is limited. The aim of this study is to assess the semi-recumbent bicycle EDE feasibility for the evaluation of RH-PCU in a large multi-center population, from healthy individuals and elite athletes to patients with overt or at risk of developing pulmonary hypertension (PH). From January 2019 to July 2019, 954 subjects [mean age 54.2 ± 16.4 years, range 16-96, 430 women] underwent standardized semi-recumbent bicycle EDE with an incremental workload of 25 watts every 2 min, were prospectively enrolled among 7 centers participating to the RIGHT Heart International NETwork (RIGHT-NET). EDE parameters of right heart structure, function and pressures were obtained according to current recommendations. Right ventricular (RV) function at peak exercise was feasible in 903/940 (96%) by tricuspid annular plane systolic excursion (TAPSE), 667/751 (89%) by tissue Doppler-derived tricuspid lateral annular systolic velocity (S') and 445/672 (66.2%) by right ventricular fractional area change (RVFAC). RV-right atrial pressure gradient [RV-RA gradient = 4 × tricuspid regurgitation velocity² (TRV)] was feasible in 894/954 patients (93.7%) at rest and in 816/954 (85.5%) at peak exercise. The feasibility rate in estimating pulmonary artery pressure improved to more than 95%, if both TRV and/or right ventricular outflow tract acceleration time (RVOT AcT) were considered. In high specialized echocardiography laboratories semi-recumbent bicycle EDE is a feasible tool for the assessment of the RH-PCU pressure and function.

What are the echocardiographic findings of acute right ventricular strain that suggest pulmonary embolism?

INTRODUCTION

Pulmonary embolism (PE) is a potentially fatal disease encountered in the hospital setting. Prompt diagnosis and management can improve outcomes and survival. Unfortunately, a PE may be difficult to diagnose in a timely manner. Point-of-care ultrasound (POCUS) can assist in the evaluation for suspected PE by assessing for acute right ventricular strain. Physicians should thus be aware of these echocardiographic findings.

OBJECTIVE

This manuscript will review ten echocardiographic findings of right ventricular strain that may suggest a diagnosis of PE. It will provide a description of each finding along with the associated pathophysiology. It will also summarize the literature for the diagnostic utility of echocardiography for this indication, while providing reference parameters where applicable. Along with labeled images and video clips, the review will then illustrate how to evaluate for each of the ten findings, while offering pearls and pitfalls in this bedside evaluation.

DISCUSSION

The ten echocardiographic findings of right ventricular strain are: increased right ventricle: left ventricle size ratio, abnormal septal motion, McConnell's sign, tricuspid regurgitation, elevated pulmonary artery systolic pressure, decreased tricuspid annular plane systolic excursion, decreased S', pulmonary artery mid-systolic notching, 60/60 sign, and speckle tracking demonstrating decreased right ventricular free wall strain.

CONCLUSIONS

Physicians must recognize and understand the echocardiographic findings and associated pathophysiology of right ventricular strain. In the proper clinical context, these findings can point toward a diagnosis of PE and thereby lead to earlier initiation of directed management.

The usefulness of subxiphoid view in the evaluation of acceleration time and pulmonary hypertension in ICU patients

BACKGROUND

Pulmonary hypertension (PHT) is very frequent in ICUs. Estimation of systolic pulmonary artery pressure (PASP) by using tricuspid regurgitation velocity (TRV) is impossible in 25% of patients. However, it may be possible to estimate PHT in these patients by obtaining subxiphoid imaging of short axis (SX-SAX) and measuring pulmonary artery diameter (PAD) and right ventricular outflow tract (RVOT) acceleration time (AT). We first aimed to compare the values of AT and PAD measured at the parasternal short axis view (PSAX) and SX-SAX and then to compare AT measurements obtained in the RVOT and pulmonary artery (PA) in ICU patients.

METHODS

This prospective observational study was conducted in a 7-bed ICU of a tertiary academic teaching hospital. Measurements of TRV, PAD, and AT in parasternal and subxiphoid SAX were obtained. AT was measured in RVOT and PA locations. We measured other echocardiographic signs of PHT to assess the probability of PHT in addition to TRV measurements.

RESULTS

The study consisted of 61 patients. TRV was measured in 85% of the patients, and SX-SAX was visualized in 78%. The probability of PHT was high (49%) in this study population. There were agreement and no proportional bias between the measurements of PAD and AT at both SX-SAX and PSAX. Measurements of AT in the RVOT and PA were similar, as well.

CONCLUSION

These results suggested that measurements of AT in the PSAX and SX-SAX and RVOT and PA were similar in the ICU patients.

Normal values of the pulmonary artery acceleration time (PAAT) and the right ventricular ejection time (RVET) in children and adolescents and the impact of the PAAT/RVET-index in the assessment of pulmonary hypertension

New echocardiographic modalities including pulmonary artery acceleration time (PAAT) and right ventricular ejection time (RVET) are evolving to facilitate an early non-invasive diagnosis for pulmonary hypertension (PH) in adults. In children, PAAT depends on age, body surface area (BSA) and heart rate (HR) and is used to predict PH. Normal values of RVET and their role to predict PH in children are still missing. PAAT/RVET-index correlates negatively with PH. We hypothesized that this index is a good predictor for PH in children and adolescents independent of age, BSA and HR and RVET is significantly reduced in PH. PAAT and RVET of 401 healthy children and 30 PH-patients were measured using pulsed-wave-Doppler. PH was diagnosed in PH-group invasively. PAAT/RVET-index for both groups was calculated. Sensitivity and specificity in prediction of PH of PAAT, PAAT z-score and PAAT/RVET-index were compared. We demonstrated normal values of RVET in children. In the healthy group, PAAT and RVET correlated significant positive to age (p < 0.001), and BSA (p < 0.001) and negative to HR (p < 0.001). PAAT/RVET-index correlated weakly to age, BSA and HR (p < 0.001). Mean pulmonary artery pressure (PAPM) ranged in the PH-group from 27 to 82 mmHg (mean 44 mmHg). In predicting PH, RVET is significantly reduced (p < 0.001). Comparing area under the curve (AUC), the difference between sensitivity and specificity of PAAT/RVET-index < 0.29 and calculated PAAT cut-off-point (87 ms) was significant (p < 0.001). Equally, AUC comparison between PAAT/RVET-index < 0.29 and PAAT z-score of - 1.33 was significant (p = 0.008). PAAT/RVET-index < 0.29 represents a good predictor of PH with a 100% sensitivity and a 95.8% specificity. PAAT/RVET-index is a simple tool and facilitates prediction of PH independent from z-scores.

Echocardiographic assessment of pulmonary hypertension: a guideline protocol from the British Society of Echocardiography

Pulmonary hypertension is defined as a mean arterial pressure of ≥25 mmHg as confirmed on right heart catheterisation. Traditionally, the pulmonary arterial systolic pressure has been estimated on echo by utilising the simplified Bernoulli equation from the peak tricuspid regurgitant velocity and adding this to an estimate of right atrial pressure. Previous studies have demonstrated a correlation between this estimate of pulmonary arterial systolic pressure and that obtained from invasive measurement across a cohort of patients. However, for an individual patient significant overestimation and underestimation can occur and the levels of agreement between the two is poor. Recent guidance has suggested that echocardiographic assessment of pulmonary hypertension should be limited to determining the probability of pulmonary hypertension being present rather than estimating the pulmonary artery pressure. In those patients in whom the presence of pulmonary hypertension requires confirmation, this should be done with right heart catheterisation when indicated. This guideline protocol from the British Society of Echocardiography aims to outline a practical approach to assessing the probability of pulmonary hypertension using echocardiography and should be used in conjunction with the previously published minimum dataset for a standard transthoracic echocardiogram.

Reference values and correlates of right atrial volume in healthy adults by two-dimensional echocardiography

BACKGROUND

Right atrial (RA) volume is an important parameter in the evaluation of patients with pulmonary hypertension. Aim of this study was to define reference ranges for RA volume by two-dimensional echocardiography (2DE) in healthy adults.

METHODS

A total of 596 healthy subjects [mean age 45.7 ± 14.6 years, range 18-88 years; 60.1% women] underwent a transthoracic echocardiography. In addition, a meta-analysis was performed of published studies measuring RA volume in healthy subjects, using 2DE single plane area-length (A-L) and/or method of disks (MOD) at end-systole in apical four-chamber view.

RESULTS

In our cohort, RA volume was higher in men than women but did not vary with age. Body surface area (BSA), stroke volume (SV), and tricuspid annular plane systolic excursion (TAPSE) were the only independent variables associated with RA volume (β coefficient 0.569, 0.123, and 0.131, respectively; all P < .001). In the pooled analysis, normalized RA volume was 25.7 ± 7.0 mL/m² in men and 21.2 ± 5.8 mL/m² in women for A-L, 21.6 ± 5.6 mL/m² in men and 18.2 ± 5.4 mL/m² in women for MOD (all P values < .0001). The upper limit was about 36 mL/m² in men and 31 mL/m² in women for A-L and 31 mL/m² in men and 27 mL/m² in women for MOD.

CONCLUSIONS

RA volume was found to be higher in men but not influenced by age. It was mainly correlated with larger BSA, indices of preload (SV) and RV longitudinal function (TAPSE). A statistically significant difference was found between A-L and MOD.

Pulmonary Hypertension and Pulmonary Artery Acceleration Time: A Systematic Review and Meta-Analysis

BACKGROUND

Measuring mean pulmonary artery pressure by right-heart catheterization is the gold standard for pulmonary hypertension (PH) diagnosis. However, its invasiveness and complication leads to its limited use. The aim of this study was to determine whether echocardiography-derived pulmonary artery acceleration time (PAAT) possesses adequate diagnostic performance for PH, using right-heart catheterization as a reference standard.

METHODS

MEDLINE, Embase, PubMed, and the Cochrane Central Register of Controlled Trials were searched through July 2016 for studies evaluating PAAT for the diagnosis of PH. Methodologic quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. For each study, the sensitivity, specificity, and diagnostic odds ratio, along with 95% CIs, were calculated to determine the diagnostic accuracy of PAAT. Meta-regression was conducted to evaluate the impact of potential confounding factors.

RESULTS

Of 430 articles, 21 studies (1,280 patients) were identified, including three studies that used transesophageal echocardiography and 18 studies that used transthoracic echocardiography. The pooled sensitivity across studies was 0.84 (95% CI, 0.75-0.90), the pooled specificity was 0.84 (95% CI, 0.78-0.89), and the pooled diagnostic odds ratio was 28 (95% CI, 16-49). The arrhythmia ratio in the population did not affect the specificity of PAAT's diagnostic performance and increased the sensitivity of PH detection.

CONCLUSIONS

The results of this study suggest that PAAT is useful for PH detection.