Effect of Heart Rate on Tissue Doppler Measures of E/E

Transcription

1 Cardiology Department of Bangkok Metropolitan Administration Medical College and Vajira Hospital, Bangkok, Thailand Abstract Background: Our aim was to study the independent effect of heart rate (HR) on parameters of diastolic function, particularly mitral annular velocities measured by tissue doppler imaging (TDI) in patients with dual chamber pacemaker. Methods: Sixteen patients with dual chamber pacemakers attending for routine pacemaker review underwent detailed echocardiographic assessment at baseline and accelerated heart rates of 60, 80, 100, and 120 beats per minute (bpm). Mitral inflow and annular tissue doppler velocity parameters were compared. Results: When these parameters were compared at baseline (mean HR 69 bpm) and an accelerated HR (80 bpm), the following was observed: a significant decrease in early mitral inflow (E) wave (0.56 ± 0.13 m/s vs 0.51 ± 0.15, p = ) and an insignificant difference of E/E (11.40 ± 1.04 vs ± 0.77 p = ). The velocity parameters could not be determined when the heart rate was more than 80 bpm. Conclusion: There was no effect of HR on E/E at a HR of 80 bpm. Keywords: Heart rate; Tissue Doppler imaging; Diastolic function; Pacemaker Thai Heart J 2009; 22 : E-Journal : Introduction Diastolic filling pattern is an important prognostic factor for survival. Doppler tissue velocity is one of the factors in determining pulmonary capillary wedge pressure (PCWP) and heart failure (HF) in patients. In general early diastolic mitral inflow velocity and mitral annular tissue velocity ratio (E/E ) is < 8, PCWP is ~ 20 if E/E ~ 15 (1). Echocardiographic assessment is an important tool in the diagnosis and management of these patients. Tissue doppler imaging (TDI) is an advancement in the assessment of diastolic function and is most accurate (2). Heart Rate (HR) is different in individual patients. From a previous study regarding changes in HR, changes compared in the same patient do not directly effect the doppler measurement (3). One study which compared patients who had a dual chamber pacemaker to measure mitral inflow velocity and mitral annular velocity ratio (E/E ) with different HRs Correspondence: Wootipong Vootiprux, MD Cardiology Department of Bangkok Metropolitan Administration Medical College and Vajira Hospital, Bangkok, Thailand address: wootipop@yahoo.com found no significant change in E/E. However the study showed a significant change in the diastolic parameter (4). Methods This study was approved by our Ethics committee. This study was performed with the consent of patients. Patients with dual chamber pacemakers were studied when they came for routine clinical follow up. Patients with unstable angina, previous mitral valve surgery, on cardiac resynchronization therapy, persistent atrial fibrillation (AF) and those unwilling to provide consent were excluded. The pacemakers of patients were temporarily reprogrammed to atrial pacing (AAI). Baseline HR was selected and echocardiography was performed. The echocardiography was performed in the left lateral position (apical four chamber view) using the GE Vivid I Echocardiograph (GE medical system). Mitral inflow velocities were obtained using the apical window with the pulsed-wave Doppler placed in the mitral valve tip in the zoom mode. Mitral annular velocities were obtained by TDI in the pulsed-wave doppler mode. The sample volume was placed at the medial septal mitral annulus. After results were obtained from the baseline HR, we used the programmer to accelerate the heart rate to 60,

2 80, 100, and 120 bpm and then measured early mitral inflow velocity, TDI septal mitral annular velocity and the E/A, E/E ratios were calculated. The echocardiogram was repeated at the fastest atrial paced rate that did not result in fusion of the mitral E and A wave. Values at baseline and accelerated HRs were compared using Paired t-tests. A P-value less than 0.05 were considered significant. Results Thirty-six patients were examined. However in 20 patients the mitral inflow E and A wave was fused with an increase in HR above baseline and thus these patients were excluded from the data. The data was collected from the remaining 16 patients (mean age 74 years, range 59-86); 8 were male and 8 were female (Table 1). The indication for a permanent pacemaker was sick sinus syndrome in 12 patients, complete heart block in 2, syncope in 1 and intermittent heart block in 1. Mitral inflow velocity could be measured accurately in all patients at baseline HRs. Tissue doppler velocity could be measured accurately in all patients at baseline HRs. The mitral inflow and annular velocities are presented in Table 2. While in some instances the HR increased to 100 and 120 bpm the fusing in the E and A waves caused exclusion of this data because they could not be calculated. The mean Mitral inflow and annular velocities are presented in Table 3. Early mitral inflow velocities decrease when HR is accelerated (p = , 95% CI ) (Figure 1). There are no significant changes between E/E at baseline and an accelerated HR to 80 bpm (p = ) (Figure 2). Table 1. Baseline characteristics Patient Gender Age Diagnosis Brand Baseline Number HR 1 Male 68 SA block DM HT Medtronic 67 2 Female 82 Trifascicular block DM HT IHD Medtronic 61 3 Female 59 CHB Medtronic 60 4 Female 72 SND HT Medtronic 61 5 Male 69 SND AF IHD s/p CABG Medtronic 66 6 Female 73 IHD SSS Medtronic 66 7 Male 77 PAF long pause Medtronic 71 8 Female 72 CHB Medtronic 71 9 Male 73 DM HT pre syncope St Jude Female 75 SND Medtronic Male 84 PAF long pause IHD Medtronic Male 61 SND Guidant Male 81 SND HT Medtronic Male 72 SND PAF Medtronic Female 86 SND PAF Medtronic Female 82 PAF sinus pause Medtronic 70 SA = sino atrial; DM = diabetes mellitus; HT = hypertension; IHD = ischemia heart disease, CHB = complete heart block; SND = sinus node dysfunction, SSS = sick sinus syndrome; PAF = paroxysmal atrial fibrillation

3 Table 2. Mitral inflow velocities and annular velocities and ratio Patient E E E E A A Baseline E/E Number baseline baseline baseline 80 E/E Table 3. Mean mitral inflow and annular velocities Mean SD Min Max E baseline E E/E Baseline E/E Discussion Mitral annulus velocity measured by TDI in early diastole gives incremental predictive power for cardiac mortality compared to clinical data and standard echocardiographic measurements. This easily available measurement adds significant value in the clinical management of cardiac patients.(6)the shorter the DT and the higher the E/Ea, the worse the prognosis (5-7). The true pathophysiologic mechanism of diastolic dysfunction needs to be elucidated, because without this knowledge the diagnostic and therapeutic strategies for patients with heart failure and normal left ventricular EF cannot be advanced (8). We need to determine whether heart failure with normal EF is one disease or if there are multiple distinct pathophysiologic disturbances leading to one clinical picture. In patients with CHF and LV systolic dysfunction, despite optimal pharmacological treatment, the strongest independent echocardiographic predictor of prognosis was a 8 m velocity measured by quantitative colour coded Doppler tissue imaging (9). This study attempted to demonstrate an independent HR on Mitral annular velocities and Tissue Doppler velocities when comparing measurements in the same patient during changes in HR. Some of these data could not be interpreted due to limited study. We observed that early diastolic annular velocities, thought to be a measure of ventricular relaxation, were lower as HR was increased. This effect was the same as previously known, specifically

4 Figure 1. E at baseline and heart rate 80 Figure 2. E/E at baseline and heart rate 80 that exercise and pharmacologic drugs have effects that increase HR. Dual chamber pacing removed the confounding effects of ventricular pacing induced dyssynchrony or changes in ventricular inotropic state. This technique allowed a constant HR to be maintained while the echocardiographic data was collected. Our data demonstrated the insignificant change in E/E ratio when the HR was increased. E/E ratio is noninvasive for filling pressure. The sample size of this study was small and there was a relatively small difference between the baseline and accelerated pacing rates as a result of difficulties in interpreting Mitral inflow patterns at higher HRs. Nonetheless both were sufficient to demonstrate significant changes in early diastolic Mitral inflow parameters with increased HR. This study was limited by the small number of patients, small differences between baseline and accelerated HRs and an unblinded observer to HR. In conclusion, we have shown that increased HR produced by dual chamber pacing results in significant changes in early Mitral inflow velocities of LV diastolic function. As a patient s HR can vary between examinations, our findings suggest that HR should be considered when interpreting echo measures of LV diastolic function and classifying diastolic function as normal or abnormal. Further study is required to determine if tissue Doppler derived annular velocities should be corrected for HR. References 1. Sohn DW, Chai IH, Lee DJ, et al. Assessment of mitral annulus velocity by Doppler tissue imaging in the evaluation of left ventricular diastolic function. J Am Coll Cardiol 1997; 30: Ommen SR, Nishimura RA, Appleton CP, et al. Clinical utility of Doppler echocardiography and tissue Doppler imaging in the estimation of left ventricular filling pressures: A comparative simultaneous Doppler-catheterization study. Circulation 2000; 102: Nagueh SF, Mikati I, Kopelen HA, Middleton KJ, Quinones MA, Zoghbi WA. Doppler estimation of left ventricular filling pressure in sinus tachycardia. A new application of tissue doppler imaging. Circulation 1998; 98: Burns AT, Connelly KA, La Gerche A, et al. Effect of heart rate on tissue Doppler measures of diastolic function. Echocardiography 2007; 24: Wang M, Yip GW, Wang AY, et al. Peak early diastolic mitral annulus velocity by tissue Doppler imaging adds independent and incremental prognostic value. J Am Coll Cardiol 2003; 41: Nishimura RA, Jaber W. Understanding diastolic heart failure : the tip of the iceberg. J Am Coll Cardiol 2007; 49: Nikitin NP, Loh PH, Silva R, et al. Prognostic value of systolic mitral annular velocity measured with Doppler tissue imaging in patients with chronic heart failure caused by left ventricular systolic dysfunction. Heart 2006; 92: Lester SJ, Tajik AJ, Nishimura RA, Oh JK, Khandheria BK, Seward JB. Unlocking the mysteries of diastolic function: deciphering the Rosetta Stone 10 years later. J Am Coll Cardiol 2008; 51: Mottram PM, Marwick TH. Assessment of diastolic function: what the general cardiologist needs to know. Heart 2005; 91:

5 ก ก E/E ก,,,, ก, ก ก : ก ก ก ก E/E ก : 16 ก 2 ก (Echocardiogram) Early Mitral inflow (E) annular Tissue Doppler velocity (Em) ก E/E ก 60, 80, 100, 120 ก : ก Early Mitral inflow (E) wave (0.56 ± 0.13 m/s ก 0.51 ± 0.15, p=0.0172) ก ก ก ( 69 ) ก 80 ก E/E ก ก 80 (11.40 ± 1.04 ก ± 0.77 p=0.5306) ก กก : ก ก E/E 80 ก ก กก