Right ventricular parameters
Right ventricular s’ and e’ waves were decreased and a’ wave tended to increase with advancing age (13.1±2.3, 12.7±2.3, 12.4±2.5, 12±2.4 cm/s for average s’ waves, 14.5±3.4, 13.9±3.2, 13.2±3.1, 11.7±3.2 cm/s for average e’ waves, 11.6±3, 12.6±3.2, 13.7±3.5, 14.9±3.5 cm/s for average a’ waves with advancing ages). Besides, a’ and e’ waves were higher in women than in men. Table-4 shows data about right ventricular TDI.
Discussion
This study provides normal reference ranges for cardiac Doppler parameters of healthy Turkish population according to age and gender using conventional recommended echocardiographic approaches including PW Doppler and TDI.
E wave and also E/A ratio were slightly higher in women than in men, and tended to decrease with advancing ages, which were statistically significant. On the other hand A wave and E wave deceleration time (Edt) were increased with advancing decades. These results were similar to data reported in European and American echocardiographic studies (2,3,6,7).
Most diastolic parameters varied and changed according to age similarly for both genders. Lateral and septal e’ were lower in men and in older population, whereas lateral a’ and septal a’ had a positive correlation with age and were slightly higher in men. These parameters were found to be prominently higher in a study authored by Nagueh et al. (8) when compared with our study . For example, the septal e’ wave velocities they obtained were 14.9±2.4 cm/s (16-20 years), 15.5±2.7 cm/s (21-40 years), 12.2±2.3 cm/s (41-60 years) and 10.4±2.1 cm/s (≥61 years) according to ages. On the other hand, Chahal et al. (9) obtained similar results when compared with our study and, reported the septal e’wave 8.6±1.9 cm/s as an average value.
For evaluation of the left ventricular diastolic function, e’, E/A and E/e’ values are highly important and are known to have a positive correlation with left ventricular filling pressures. In our study we did not observe any value of septal (and also lateral) e’ lower than 8 cm/s whereas in the study authored by Cabellero et al. (10) 2 out of 170 (1.2%) in 20-40 years, 38 out of 193 (19.7%) in 40-60 years, 46 out of 83 (55.4%) in ≥60 years had values lower than 8 cm/s. Indeed, LAVI of participants were lower than 34 mL/m² in all age groups. E/A ratio was decreased with increasing age, as shown in several previous studies (10-13). E/e’ tended to increase in older ages but none of the participants had a value higher than 15, although it has been reported in some European studies (11). In the present study, E/e’ was found to be slightly higher in women compared to men, although it was not statistically significant. Several studies have previously showed that there is relatively a higher incidence of deteriorated diastolic functions in elderly female patients and higher cardiovascular mortality in female gender when compared to men (14-16).
s’ wave velocity measures longitudinal LV contraction and is a surrogate of LV systolic function and it is also well-known that it has a good correlation with left ventricular ejection fraction (LVEF). s’ wave velocity ≥7.5 cm/s has a sensitivity of 79% and a specificity of 88% in predicting LVEF ≥50% (2, 17). As summarized in Table-3, lateral s’ was higher than septal s’ in our study and also higher in younger volunteers. Lateral s’ was higher in men whereas septal s’ was higher in women, concordant with previous data (12,13).
Meluzin and co-workers (17), reported good correlation between right ventricular (RV) s’ wave velocity and right ventricular ejection fraction (RVEF); RV s’ wave velocity <11.5 cm/s predicted RV dysfunction (EF < 45%) with a sensitivity of 90% and specificity of 85%. In our study, none of the participants had a lower RVs wave than these established data. Ischemic heart diseases, chronic pulmonary hypertension and chronic lung diseases can cause a decrease in RV s’ wave velocity which should be evaluated during echocardiographical examinations.
In the present study, right ventricular parameters also exhibited gender-related differences, e’ and a’ were higher in women whereas s’ wave was higher in men. s’ and e’ wave velocities were decreased with advancing ages as demonstrated in previous studies (10,11, 13).
Systolic pulmonary artery pressure (sPAP), an important predictor of several cardiac abnormalities, was also evaluated in the current study. We did not obtain any sPAP above 36 mmHg in healthy volunteers, whereas, higher levels have been rarely detected in past studies (11). However, it should be kept in mind that echocardiography is a observer-dependent modality, and the patients with slightly elevated pulmonary artery pressure should be evaluated with further imaging modality to avoid under-diagnosis of any organic heart disease.
In conclusion, the current data obtained from healthy Turkish volunteers are comparable with most previous studies in this era (2,3,5,6,10,11,13,18). E and A waves of mitral annulus and also E/A ratios were greater compared to European registries, but these differences were not statisitically significant. Data regarding E/e’ ratio especially seems interesting, as in a European study (6) that it has been found to be significantly increased in advancing ages whereas no remarkable difference has been detected in our study. But we have to emphasize that E/e’ higher than 15 is correlated with diastolic dysfunction and the study above-mentioned had several participants with these values (0.05% of the population) (11).
As being the first large-scaled healthy population based Doppler study in Turkey, ECHO-DOP-TR provides essential data regarding left and right ventricular PW Doppler and TDI studies, and helps us to evaluate the systolic and diastolic functions of the heart.
Limitations
The results mainly pertain to Turkish population who live in Turkey, a bridge country between Europe and Asia. Despite the fact that all patients were considered healthy normal subjects, the possibility of subclinical coronary artery disease particularly in older subjects cannot be excluded. The study groups were not equally distributed according to age as it was not easy to find healthy patient without any chronic disease in advancing ages. The data regarding e’ and a’ waves in inferior, anterior, posterior segments are unavailable in most of the patients and therefore were not included in the Results section.