Exercise cardiovascular magnetic resonance imaging allows differentiation of low-risk pulmonary arterial hypertension

BACKGROUND

Patients with pulmonary arterial hypertension (PAH) have a decreased ability to compensate for demands on increased cardiac output, such as during exercise. In this study we aimed to differentiate cardiac exercise responses in patients with PAH, stratified according to known measurements of disease severity.

METHODS

Right and left ventricular end-diastolic volume and end-systolic volume, stroke volume (SV), and cardiac output were measured in 20 patients with PAH and a lower risk of mortality with 6-month intervals using cardiovascular magnetic resonance (CMR) imaging during rest and during ergometer exercise (totaling 44 scans). Exercise measurements were compared with resting cardiac conditions and clinical assessment using mixed model statistics.

RESULTS

SV response during exercise was associated with disease severity. World Health Organization functional class (WHO FC) I and right ventricular end-diastolic volume (RVEDV) <221 ml were associated with increased SV during exercise (WHO FC I: 7% increase in SV; p < 0.001). In contrast, WHO FC II was associated with an 8% decrease in SV (p = 0.02), and SV response declined progressively with right ventricular dilation (7-ml decrease in SV per 100-ml increase in RVEDV; p < 0.001).

CONCLUSIONS

Assessment of right ventricular function with CMR during exercise stratifies patients currently perceived as having a low risk of mortality into different degrees of right ventricular inotropic reserve. Reduced SV during exercise is a plausible factor to increased risk of decompensation, possibly warranting targeted therapy intensification to restore right ventricular functional reserve.

Exercise echocardiography for the assessment of pulmonary hypertension in systemic sclerosis: a systematic review

BACKGROUND

Pulmonary arterial hypertension (PAH) complicates the course of systemic sclerosis (SSc) and is associated with poor prognosis. The elevation of systolic pulmonary arterial pressure (sPAP) during exercise in patients with SSc with normal resting haemodynamics may anticipate the development of PAH. Exercise echocardiography (ExEcho) has been proposed as a useful technique to identify exercise-induced increases in sPAP, but it is unclear how to clinically interpret these findings. In this systematic review, we summarize the available evidence on the role of exercise echocardiography to estimate exercise-induced elevations in pulmonary and left heart filling pressures in patients with systemic sclerosis.

METHODS

We conducted a systematic review of the literature using MEDLINE, Cochrane Library and Web of Knowledge, using the vocabulary terms: ('systemic sclerosis' OR 'scleroderma') AND ('exercise echocardiography') AND ('pulmonary hypertension'). Studies including patients with SSc without a prior diagnosis of PAH, and subjected to exercise echocardiography were included. All searches were limited to English and were augmented by review of bibliographic references from the included studies. The quality of evidence was assessed by the Effective Public Health Practice Project system.

RESULTS

We identified 15 studies enrolling 1242 patients, who were mostly middle-aged and female. Several exercise methods were used (cycloergometer, treadmill and Master's two step), with different protocols and positions (supine, semi-supine, upright); definition of a positive test also varied widely. Resting estimated sPAP levels varied from 18 to 35 mm Hg, all in the normal range. The weighted means for estimated sPAP were 22.2 ± 2.9 mmHg at rest and 43.0 ± 4.3 mmHg on exercise; more than half of the studies reported mean exercise sPAP ≥40 mmHg. The assessment of left ventricular diastolic function on peak exercise was reported in a minority of studies; however, when assessed, surrogate variables of left ventricular (LV) diastolic dysfunction were associated with higher sPAP on exercise.

CONCLUSIONS

We found very high heterogeneity in the methods, the protocols and the estimated sPAP response to exercise. LV diastolic dysfunction was common and was associated with greater elevation of sPAP on exercise.

Detection of exercise-induced pulmonary arterial hypertension by cardiopulmonary exercise testing

BACKGROUND

The pulmonary arterial pressure (PAP) response to exercise may provide a tool for the early detection of pulmonary arterial hypertension (PAH). Therefore, an accurate noninvasive method for evaluating exercise-induced PAH (EIPAH) is desirable.

HYPOTHESIS

We sought to examine if cardiopulmonary exercise testing (CPET) is able to indicate EIPAH.

METHODS

Fifty-three patients aged 67.1 ± 1.7 years (37 female, 16 male) with borderline PAH (resting mean PAP 21-24 mm Hg) performed CPET and right heart catheterization at rest and during handgrip testing.

RESULTS

When comparing patients with an exercise-induced mean PAP ≥ mm Hg (group A, n = 24) and subjects with an exercise-induced mean PAP <35 mm Hg (group B, n = 29), group A had a significantly lower mean aerobic capacity (15.2 ± 1.2 vs 19.7 ± 1.2 mL/min/kg; P = 0.02), higher ventilatory equivalents for oxygen at the anaerobic threshold (34.3 ± 1.5 vs 29.9 ± 1.1; P = 0.02), a widening of the mean alveolar-arterial oxygen difference (37.8 ± 3.0 vs 26.8 ± 2.4 mm Hg; P = 0.007), an elevated mean functional dead space ventilation (29.5 ± 2.7 vs 21.2 ± 1.7%; P = 0.008), and a higher mean arterial to end-tidal carbon dioxide gradient at peak exercise (3.7 ± 0.9 vs 0.4 ± 0.8 mm Hg; P = 0.007).

CONCLUSIONS

EIPAH is characterized by a decreased ventilatory efficiency due to ventilation to perfusion inequalities. CPET may be useful for the identification of EIPAH and serve to diagnose PAH at an early stage.

Early detection of pulmonary vascular disease in pulmonary arterial hypertension: time to move forward

Pulmonary arterial hypertension (PAH) can be a rapidly progressive disorder and is associated with high rate of mortality, despite medical intervention. With the availability of effective therapy, early disease detection is an important strategic objective to improve treatment outcomes. Resting echocardiography is currently the recommended screening modality for high-risk population groups. However, it is clear that derangements in resting haemodynamics (and symptoms) are late sequelae of the pathobiological processes that begin in the distal pulmonary arteries. Exercise stress may unmask early pulmonary vascular dysfunction but the definition, clinical significance, and natural history of 'exercise PAH' remain undefined. We will review the currently available and potential future strategies aimed at early disease detection, and propose that ultimately the way forward is to detect disease at a stage prior to the rise in resting pulmonary artery pressure.

Estimated right ventricular systolic pressure during exercise stress echocardiography in patients with suspected coronary artery disease

OBJECTIVE

To determine the normal range of estimated right ventricular systolic pressure (RVSP) at peak exercise during exercise stress echocardiography (ExECHO) in a series of consecutive patients referred for the investigation of coronary artery disease.

METHODS

Of 1057 ExECHO examinations over a span of 11 months, 807 met the study criteria. A total of 250 patients were excluded, 188 for missing rest or peak RVSP measurements, 16 for a resting RVSP above 50 mmHg, 16 for nondiagnostic echocardiographic images and the remaining 30 for missing data. The maximal tricuspid regurgitant jet was recorded at rest and following acquisition of the stress images (mean [+/- SD] time 103.1+/-35.2 s). A mean right atrial pressure of 10 mmHg was used in the calculation of RVSP. All data were entered into a cardiology database (CARDIOfile; Registered trademark, Kingston Heart Clinic) for later retrieval and analysis.

RESULTS

There were 206 male (58.9+/-12.0 years of age) and 601 female patients (57.4+/-12.0 years of age). Patient age ranged from 18 to 90 years. The mean resting and peak exercise RVSP was 27.8+/-7.8 mmHg and 34.8+/-11.3 mmHg in men, and 27.8+/-7.7 mmHg and 34.6+/-11.7 mmHg in women, respectively. The mean increase in RVSP was 7.0+/-8.8 mmHg in men and 6.7+/-8.9 mmHg in women. The 95% CI for peak RVSP was 12.2 mmHg to 57.4 mmHg in men, and 11.2 mmHg to 58.0 mmHg in women. There was no significant difference in peak RVSP for a normal ExECHO compared with an abnormal ExECHO. RVSP at rest and at peak exercise increased with both age and left atrial size.

CONCLUSIONS

In individual patients, the RVSP should not increase above the resting value by more than 24.6 mmHg in men and 24.5 mmHg in women. This value was calculated as the increase in RVSP plus 2xSD of the RVSP. Peak RVSP should not exceed 57.4 mmHg in men and 58.0 mmHg in women. If either of these criteria is exceeded, the response of RVSP to exercise should be considered abnormal.

Non-invasive measurement of the response of right ventricular pressure to exercise, and its relation to aerobic capacity

INTRODUCTION

Exercise echocardiography assesses exercise-induced pulmonary hypertension. The upper normal limit of right ventricular systolic pressure during exercise is not well established. Our study aims to investigate the response of right ventricular systolic pressure in relation to aerobic capacity.

METHODS AND RESULTS

Cardiopulmonary exercise testing using a treadmill, and echocardiography during supine cycling, were performed in 113 healthy volunteers aged 13 to 25 years. Maximal right ventricular systolic pressure during evaluable exercise studies obtained in 108 subjects showed a Gaussian distribution only after separating the endurance trained subjects, specifically 12 athletes with Z-score of peak oxygen uptake higher than 2.0, from the normally trained group of 97 subjects. Maximal right ventricular systolic pressure during exercise in the normally trained group showed a mean of 38.0 millimetres of mercury, with standard deviation of 7.2, a median value of 39.0, and a range from 17 to 63, and the 95th percentile was 51 millimetres of mercury. In the athletes, the maximal right ventricular systolic pressure was higher, with a median of 55.5, a range from 28 to 69, this being significant, with p equal to 0.004). Of the 12 athletes, 8 (67%) showed a response of right ventricular systolic pressure to exercise exceeding 50 millimetres of mercury, but only 8 of 97 normally trained subjects (8%) showed a similar response, this also being significant, with p less than 0.001.

CONCLUSIONS

Our study confirms the great variability in the response of right ventricular systolic pressure to exercise in healthy individuals, with 50 millimetres of mercury representing the upper normal limit. Endurance-trained athletes show higher levels, and two-thirds have abnormal responses exceeding 50 millimetres of mercury.

The usefulness of contrast during exercise echocardiography for the assessment of systolic pulmonary pressure

BACKGROUND

The systolic pulmonary artery pressure (PAPs) can be accurately estimated, non-invasively, using continuous-wave Doppler (CWD) ultrasound measurement of the peak velocity of a tricuspid regurgitant (TR) jet. However, it is often difficult to obtain adequate tricuspid regurgitation signals for measurement of PAPs, what could lead to its underestimation. Therefore, utilization of air-blood-saline contrast has been implemented for the improvement of Doppler signal in several clinical contexts. It is now recommended in the evaluation of patients with pulmonary hypertension. Physical activity is severely restricted in patients with PAH, being exertional dypnea the most typical symptom. Exercise stress echo-Doppler imaging allows assessment of the response to exercise. It is an excellent screening test for patients with suspected PAH. Our purpose was to evaluate the value and accuracy of agitated saline with blood contrast echocardiography, in the improvement of the Doppler signal, to quantify PAPs during treadmill exercise-echocardiography.

PURPOSE

To evaluate the value of contrast echocardiography, using agitated saline with blood, in the improvement of the Doppler signal used to quantify the pulmonary artery systolic pressure during exercise.

METHODS

From a total of 41 patients (pts), we studied 38 pts (93%), 35 women, aged 54 +/- 12 years-old. 27 with the diagnosis of systemic sclerosis, 10 with history of pulmonary embolism and one patient with a suspected idiopathic PAH, who were referred to the Unity of Heart Failure and Pulmonary Hypertension for screening of PAH. According to the Unity protocol, a transthoracic echocardiogram was made, in left decubitus (LD), with evaluation of right ventricle-right atria gradient (RV/RAg). A peripheral venous access was obtained, with a 3-way stopcock and the patients were placed in orthostatism (O), with a new evaluation of RV/RAg. Exercise echocardiography (EE) was begun, with evaluation of RV/RAg at peak exercise (P) and afterwards agitated saline (8 cc with 1 cc of air and 1 cc of blood) was injected, followed by a new evaluation of RV/RAg (PC) and then the interruption of the EE. Pulmonary Hypertension was diagnosed when RV/RAg at the end of the exercise was superior to 40 mmHg.

RESULTS

The quality of Doppler signal was deteriorated in 5 pts, maintained in 6 pts and improved in 26 pts, with the use of contrast. In one patient, an interventricular septal defect was diagnosed. In 6 pts, a Doppler signal was only obtained with the use of contrast. In 15 pts, a RV/RAg superior to 40 mmHg was only obtained with the use of contrast. Of these, 9 have already been submitted to right heart cathetherism, that confirmed the diagnosis of pulmonary hypertension in 5 of them (56%). RV/RAg (P) was 44 +/- 11 mmHg and RV/RAg (PC) was 54 +/- 11 mmHg, p < 0,001.

CONCLUSION

1. The method is applicable in a large number of patients. 2. RV/RA gradients obtained at peak exercise are higher with the use of contrast, and the clinical meaning of this difference should be evaluated in a larger number of pts submitted to right heart cathetherism. The high number of false positives should lead to a higher diagnostic threshold. 3. This method seems to have relevant clinical value in the diagnosis of pulmonary arterial hypertension.