We have defined the increase and normal ranges for RVSP during ExECHO in male and female patients, normal and abnormal ExECHO responses, and for different age groups. These patients are predominantly referred to our facility for investigation of symptoms to rule in or rule out myocardial ischemia. To our knowledge, our paper is the first to report such data in this population. The study by Bossone et al (3
) is the only previous study to investigate RVSP during ExECHO but only in normal subjects, whereas numerous studies have investigated the response of RVSP to exercise in patients after cardiac transplantation (8
), congenital heart disease (9
) and atrial septal defect (10
). The population in the Bossonne et al study did not include any female individuals, and consisted of highly conditioned male athletes (n=26, mean age 20 years) and young, healthy male controls (n=14, mean age 19 years). The present study has shown, and previous studies have also suggested, that resting RVSP increases progressively and normally with age (11
). Therefore, we believed it was necessary to define the normal range of RVSP with ExECHO across a much wider range of ages. Our population more accurately reflects the range in age of patients seen in the typical outpatient cardiology clinical setting.
Overall, there was no significant difference between men and women for age, resting RVSP, peak exercise RVSP and ΔRVSP (). In elderly patients, our data indicate that RVSP may approach 65 mmHg at peak exercise. Bossone et al also found that RVSP could approach this value in highly conditioned male athletes (3
). Others have shown that in normal controls (n=12; 11 men), the mean RVSP increased from 22 mmHg at rest to 31 mmHg at peak exercise, whereas in patients with chronic pulmonary disease, RVSP increased from 46 mmHg at rest to 83 mmHg at peak exercise (14
). Similarly, in patients with congestive heart failure, RVSP increased from 45 mmHg at rest to 73 mmHg at peak exercise (15
). We believe these data underscore the necessity of considering the clinical presentation of symptomatic patients with cardiopulmonary disease when assessing the response of RVSP to exercise as normal or abnormal.
We found that both resting and peak exercise RVSP increased significantly with age. There was no significant relationship using linear regression analysis between RVSP and SBP, either at rest or peak exercise. Furthermore, men and women had similar resting and peak exercise RVSPs, despite the fact that men had significantly higher resting and peak exercise SBPs than women. Contrary to previous work investigating SBP and RVSP (16
), our data indicate that SBP does not accurately predict the response of RVSP to exercise. However, when we differentiated the normal ExECHOs from the abnormal ExECHOs, a nonsignificant trend was found for a negative correlation between peak RVSP and peak SBP in patients with an abnormal ExECHO. This is an interesting finding that suggests that a lower SBP response to exercise may be a reflection of impaired LV systolic or diastolic function or indeed both. More abnormal ExECHO data are required to confirm this finding.
We observed that men had significantly lower ejection fractions than women (57.7±10.0% versus 61.6±8.0%; P<0.0001). This may simply be a reflection of the fact that a greater proportion of male patients had an abnormal ExECHO than the female patients (28.6% versus 13.5%).
In our laboratory, if a patient exceeds the accepted range for peak exercise RVSP, a bubble study is performed to exclude intracardiac shunting, specifically at the atrial level. If there is any such evidence, a transesophageal echocardiogram may be required. If the bubble study is normal, patients may need a workup for pulmonary hypertension, such as a ventilation/perfusion scan to exclude pulmonary embolism and pulmonary function studies. If appropriate on clinical grounds, a sleep study may be required.
Limitations of our study deserve attention. The TR jet was measured both at rest, and slightly after peak exercise, due to the time required for acquisition of the stress images. Therefore, the increase and normal ranges of peak exercise RVSP may have been underestimated. The selection of 10 mmHg as an appropriate RAP surrogate in this population is also questionable. The range of normal pressures would be 5 mmHg lower if 5 mmHg had been chosen.
Having shown here that RVSP increases with age, both at rest and peak exercise, and previous studies showing that resting RVSP increases with body mass index (16
), further studies will be required to define the normal range of peak exercise RVSP according to body mass index. The relative lack of male compared with female patients reflects a local bias in performing routine exercise treadmill testing in male patients and exercise echocardiography in female patients. We do not have pre-exercise or postexercise Doppler information concerning concomitant valvular heart disease, specifically mitral valve disease. We examined our data with respect to LA size, and there was a significant difference in RVSP between patients with an LA size of 40 mm or less, and those with a size greater than 40 mm. It is possible that the patients with increased LA size had other echocardiographic abnormalities such as significant mitral regurgitation or abnormal LV diastolic function. A full Doppler examination was not part of our routine ExECHO protocol. Finally, the Kingston Heart Clinic is an outpatient cardiac facility and approximately 80% of our referrals come from family physicians. This referred population likely has a relatively low prevalence of coronary artery disease. This is reflected in the observation that only 17% of our ExECHOs were abnormal.