Effect of increasing heart rate on Doppler indices

Transcription

1 Br Heart J 1992;68: MESUREMENT Effect of increasing heart rate on Doppler indices of left ventricular performance in healthy men T Oniki, Y Hashimoto, S Shimizu, T Kakuta, M Yajima, F Numano bstract Objective-To investigate the effects of heart rate on the Doppler measurements of left ventricular function and to determine the normal pattern of rate dependency. Setting--University hospital specialising in internal medicine. Participants-14 healthy male volunteers 1 of whom were studied. ntervention: Transoesophageal atrial pacing. Main outcome measures-t paced rates of 7, 8, and 9 ppm the ratio of early to late peak transmitral flow velocity (E) was 1P97 (-28), 1'49 (-21), and 95 ( 11) respectively; the ratio of early to late time-velocity integrals of transmitral flow (Ei/i) was 3 3 (-51), 2-11 ('24), and 1-14 ( 3) respectively; and the atrial filling fraction (FF) was -17 (-3), -21, ( 4), and -24 ( 4) (mean (SD)). Results-Heart rate showed a linear correlation with E/ (r2 = 86), Eiji (r2 = -838), and FF (r2 = -343). Neither the peak aortic flow velocity or the mean aortic flow acceleration showed significant changes during pacing at rates of 7, 8, 9, and 1 ppm. nclusions-e and Ei/i can be expected to decrease by 5 and 9 for each increase of 1 beats/min in heart rate. Knowledge of this relation may be useful for the development of algorithms to correct for heart rate when diastolic Third Department of function is assessed. nternal Medicine, Tokyo Medical and (Br Heart J 1992;68:425-9) Dental University, School of Medicine, Tokyo, Japan T Oniki Doppler echocardiography is a useful non- Y Hashimoto invasive procedure for evaluating left ven- T Kakuta tricular systolic'2 and diastolic34 functions. M Yajima Physiological variables, including the heart F Numano rate, affect cardiac performance and Doppler rrespondenceto measurements." However, the normal T Oniki, Third Department mesrmns6hovr,teomapten pattern of nternal Medicine, Tokyo of heart rate dependency of those measure- Medical and Dental ments is still unclear. Clarification of the rela- University, School of Medicine, Yushima, tion between the heart rate and left ventricular Bunkyo-ku, Tokyo 113, performance in healthy individuals Would Japan. allow the application of echocardiography to ccepted for publication be refined. We studied the influence of alterations in heart rate on Doppler indices of left ventricular performance. Subjects and methods STUDY POPULTON We recruited 14 healthy male volunteers; four were excluded because of intolerable discomfort caused by pacing, unsatisfactory Doppler recordings, or a high sinus rate. The remaining 1 men (aged 25-3 (27-2 (1 7)) were free of illness as determined by their history and physical examination as well as by 12 lead electrocardiogram and echocardiogram. We obtained informed consent before the study. The men were fasting, non-sedated, and were receiving no medications at the time of the study. TRNSOESOPHGEL TRL PCNG 6F quadripolar pacing catheter was passed through the nose and into the oesophagus. The distal or proximal pair of electrodes was used for bipolar pacing and the other pair for monitoring. The initial position was determined as reported by Benson et al.7 Final positioning of the electrode was accomplished by electrocardiographic monitoring during electrode adjustment to obtain consistent left atrial capture. Stable capture required 15 ms pulses of 1 to 22 m intensity provided by the pacing device (BC2 and BC2EP, Fukuda Denshi, Tokyo, Japan). fter electrode placement, the men rested for at least 1 minutes to stabilise heart rate and blood pressure. Echocardiography was subsequently performed at the resting heart rate and was repeated at each paced rate. trial pacing was started at a paced rate of 7 ppm. We then increased the rate of atrial pacing by 1 ppm to a maximum of 1 ppm. To ensure haemodynamic stabilisation at each paced rate we waited three minutes before the echocardiogram was recorded. 12 lead electrocardiogram was also recorded at each paced rate. ECHOCRDOGRPHC STUDY Echocardiography was performed with the subject in the supine or left lateral position. commercial phased array imaging system (SSH 16, Toshiba, Tokyo, Japan) with pulsed wave and continuous wave Doppler capabilities was used. We used a 2-5 MHz imaging transducer for Doppler echocar-

2 426 Bradycardia Mitral flow measurements Tachycardia ortic flow measurements Ei i C L- FF = C/total filling area Figure Peak early (E) and late () mitralflow velocities and early (Ei) and late (i) time-velocity integrals were obtainedfrom the mitralflow velocity curve. The atrial filling fraction (FF) was determined as the ratio of the area (C) above the extrapolated line (broken line) from the passivefilling wave to the totalfilling area. Peak aorticflow velocity (Pko) and mean aorticflow acceleration (co) were obtained from the aorticflow velocity curve. diography and a 2-5 MHz non-imaging continuous wave Doppler transducer. Doppler recordings of mitral flow velocity were performed with the transducer at the cardiac apex. n apical four chamber view of the heart was used to align the Doppler cursor parallel with the apparent flow direction and the sample volume was placed at the level of the mitral annulus. Then the sample volume was moved slightly (with the aid of the audio signal and spectral display) to maximise the signal-tonoise ratio. ortic flow velocities were recorded from the suprasternal notch with a non-imaging Oniki, Hashimoto, Shimizu, Kakuta, Yajima, Numano transducer angulated to record the maximal flow velocity signal in the ascending aorta. Doppler signals were recorded on a strip chart at a paper speed of 1 mm/s. The following measurements were obtained from the recordings as shown in fig 1. The mitral flow velocity curve was characterised by the early filling wave (E wave) and late filling wave ( wave). The peak flow velocities of an E wave (E) and an wave () were measured and the E/ ratio was calculated. The timevelocity integrals of an E wave (Ei) and an wave (i) were measured as the area under those flow velocity curves and the Ei/i ratio was also calculated. The atrial filling fraction (FF) was determined by the method of Kuo et al.8 This index was measured as the ratio of the area above the extrapolated line from the passive filling wave (C) to the total filling area. The peak flow velocity (Pko) and the mean acceleration from the onset of ejection to Pko (co) were measured from the aortic flow recording. Each measurement was obtained as a mean value of five consecutive beats to correct for beat to beat variation in the observed values. The mean coefficients of variation of the five observed measurements of the E,, and Pko at resting sinus rhythm were 5, 12, and 3%, respectively. STTSTCL NLYSS Values are expressed as mean (SD) in the text and as mean (SEM) in the figures. The relation between the measurements and heart rate was analysed by analysis of variance. We obtained the regression line as well as the coefficient of determination (r2), which was the ratio of the variance associated with the linearity (SLin) to the total variance of the measurement. The ratio of the SLin to the variance related to the changes in heart rate (r'2) was also obtained as an index of the Figure 2 Doppler recording obtainedfrom a representative subject. Sinus rhythm 62 bpm trial paced rhythm 7 bpm 8 bpm 9 bpm 1 bpm 3. o L 3i * CL E 4i1*l ~ 1~~~~~ i yv* -*.~ ~ ~~5 ~lii ~t~*g k~. L~ ~~~~~~~~~~~-

3 Effect of heart rate on left ventricular performance 427 Figure 3 Relation between heart rate and E/ (), E (circles), and (squares) (B). The curvilinear lines indicate the 95% confidence intervalfor the regression lines for a particular point. r = coefficient of determination; 2= coefficient of the linearity of the relation between heart rate and the measurement; SE(/3), standard error of the slope of the regression line. w C.. _ CY) 4-2._ CC 1 y = x r2= -86 r2 =.997 SE(,3) = 362 (i E ) ~ ~ 1-5 B y() = x r2= -696 r2 = -929 SE(,) = linearity of the relation between the heart rate and the measurement without the influence of other factors, including the intersubject variance and the error. p value < 5 was regarded as significant. Results Before pacing the mean heart rate was 62 6 (3 3) bpm. The mean resting systolic and diastolic blood pressures were (5 7) and 7-6 (8-3) mm Hg. No abnormalities, including ischaemic ST changes, were seen in the 12 lead electrocardiogram during the study. Figure 2 shows mitral and aortic Doppler recordings from one man. The transmitral flow pattern apparently changed with increasing heart rate whereas the aortic flow changed only slightly. Data from all the men were analysed as follows. EFFECT OF TRL PCNG ON MTRL FLOW n increase in heart rate reduced the E/ ratio (fig 3). There was an inverse linear relation during pacing (E/ = x HR (bpm) (r2 = 86, r'2 =.997). Mean values of during pacing were also significantly affected by a change in heart rate. was positively correlated with heart rate ( (m/s) = x HR(bpm)(r2 = 696, '2 r' = 929). This relation was somewhat curvilinear. The fact that the variance in the non-linear part ofthis relation was significant (p Figure 4 Relation between heart rate and Ei/i () and FF (B). See legend to fig 3 for abbreviations. w._ -i B E 4, 4 - C ) ) a Ū- C._ C._ 2- C4o 2 ) c: - y = x r2 = -838 r'2= 1 SE(,) -285 = o

4 428 Oniki, Hashimoto, Shimizu, Kakuta, Yajima, Numano -Ē 1 o i._cj o 5 81) Figure U) B viduals. Smith et al studied the effects of E increased heart rate and blood pressure caused 3 by cold immersion in normal volunteers.'3 u 2 However, the effect of cold immersion can be c attributed to the sympathetic nerve stimulation which may change cardiac function as well as heart rate.'415 Harrison et al studied the differences between the E,, and E/ at a resting Cr.) ~ f heart rate with sinus rhythm and at a heart rate of 9 bpm during transoesophageal atrial pacing.6 They reported that pacing increased C2 and reduced E/. Van Dam et al studied the C relation between the E/ and resting heart rate and age in healthy volunteers and reported that 8) a higher heart rate was associated with a lower E/.'7 s the Doppler indices of diastolic function, including the E/, Ei/i and FF depend on the heart rate, their application to individual subjects requires knowledge of the pattern of their rate dependency. We studied the pattern of the dependency in young healthy < 5) compared with the residual variance men with normal diastolic function. supported this observation. E, however,did We found that heart rate correlated closely not change significantly with an increatse in with E/ and Ei/i. Furthermore, because the heart rate (fig 3B). s with the time-vellocity relation was linear it may be useful in the integrals, the Ei/i ratio was negatively cordevelopment of algorithms that will correct for related (Ei/i = x HR (b)pm), heart rate and enhance the non-invasive assessposl- ment of diastolic function in individuals. The r = -838, r" = 1 ) and FF was tively correlated (FF = x HR (bpm), r2 = 343, r '2 = pattern of dependency also needs to be studied -996) with in individuals with impaired diastolic function. heart rate (fig 4). The C showed no signifficant n addition, the apparent increase in and in change with pacing rate. n increase i heart rate to 1 ppm during atrial p n the i may be attributed to the effect of the acing superimposition of the wave onto the resulted in overlapping of the and E wav that the Doppler indices ofmitral flow coul{es so descending limb of the E wave. Pearson et al d not reported that PR prolongation increased i and be determined. that the effect might be caused by superimposi- Relation between heart rate and the Pko () and co (B). EFFECT OF TRL PCNG ON ORTC FLOW tion.18 We too suggested that superimposition might be important in the effect of heart rate on No significant changes in mean values of ] Pko and co were seen with increasing Ei/i.'9 The fact that FF showed only a weak heart rate correlation and C showed no significant (fig 5). correlation with heart rate in the present study supports this concept. Our present study had some limitations. Discussion There was a small but significant increase in the Doppler echocardiography provides blood flow interval between the pacing artefact and the velocity measurements, and various Dop)pler- QRS complex (187 (14), 27 (15), and 217 (19) derived indices have been used to evaluate ms at paced rates of 7, 8, and 9 ppm, cardiac function.9 However, Do: ppler respectively). Because an increase in PR 1 echocardiography cannot be simply appliied to interval (as well as an increase in heart rate) individuals because those indices carn be causes more superimposition, the effects of influenced by various physiological variaibles. changes in heart rate may have been enhanced We found linear relations between heartt rate in the present study. and E/, Ei/i, and FF in 1 healthy yroung men. This provides a basis for correcting the ORTC FLOW VELOCTY MESUREMENTS Doppler-derived indices of left ventriicular ortic flow velocity and acceleration are known diastolic function. to reflect the left ventricular systolic function.'2 Some investigators have studied the effects MTRL FLOW VELOCTY MESUREMENTS of heart rate on aortic flow measurements. There have been some reports of the effe( cts of Wallmeyer et al reported that the peak aortic heart rate on the diastolic measurennents flow velocity as well as the mean acceleration of obtained with Doppler echocardiogreaphy. aortic flow showed a strong correlation with the Gillam et al reported that an increase in heart max dp/dt and max dq/dt and was indepenrate increased the and decreased E, E/L, and dent of the heart rate in dogs.2 On the other Ei/i in the patients with pacemakers. " Herzog hand, Harrison et al in a study of healthy et al showed similar results in patients ui nder- volunteers found an inverse relation between going cardiac catheterisation.12 These rcesults the heart rate and peak aortic flow velocity and suggest that an increase in heart rate mayy lead acceleration.5 They attributed this to a decrease to an increase in flow velocity and vy lume in the end diastolic volume caused by the during atrial systole. However, few such increased heart rate. We found no relation studies have been conducted in healthy indi- between aortic flow measurements and heart

5 Efject ofheart rate on left ventricular performance rate. Harrison et al compared the aortic flow measurements at the resting heart rate and at heart rates of from 9 to 15 ppm during atrial pacing, whereas we used paced rates of from 7 to 1 ppm. t these low rates a change of heart rate may produce only minimal changes in the Doppler-derived systolic measurements. The relation between heart rate and measurements of aortic flow and mitral flow in health and disease should be further investigated. We thank Dr Sakuma, Professor of Clinical Pharmacology, Medical Research nstitute, Tokyo Medical and Dental University, for his advice on the statistical analysis of the results in this study. 1 Bennett ED, Barclay S, Davis L, Mannering D, Mehta N. scending aortic blood velocity and acceleration using Doppler ultrasound in the assessment of left ventricular function. Cardiovasc Res 1984;18: Daley PJ, Sagar KB, Wann LS. Doppler echocardiographic measurement offlow velocity in the ascending aorta during supine and upright exercise. Br Heart J 1985;54: Rokey R, Kuo LC, Zoghbi W, Limacher MC, Quinones M. Determination of parameters of left ventricular diastolic filling with pulsed Doppler echocardiography: comparison with cineangiography. Circulation 1985;71: Spirito P, Maron BJ, Bonow RO. Noninvasive assessment of left ventricular diastolic function: comparative analysis of Doppler echocardiographic and radionuclide angiographic techniques. J m ll Cardiol 1986;7: Harrison MR, Clifton GD, Sublett KL, DeMariaN. Effect of heart rate on Doppler indexes of systolic function in humans. J m ll Cardiol 1989;14: Plotnick GD. Changes in diastolic function: difficult to measure, harder to interpret. m Heart J 1989;118: Benson DW Jr, Dunnigan, Benditt DG, Schneider SP. Transesophageal cardiac pacing: history, application, technique. Clin Prog Electrophysiol 1984;2: Kuo LC, Quinones M, Rokey R, Sartori M, binader EG, Zoghbi W. Quantification of atrial contribution to left ventricular filling by pulsed Doppler echocardiography and the effect of age in normal and diseased hearts. m J Cardiol 1987;59: Saeian K, Wann LS, Sagar KB. Doppler echocardiographic evaluation of left ventricular function. Echocardiography 199;7: Labovitz J, Pearson C. Evaluation of left ventricular diastolic function: clinical relevance and recent Doppler echocardiographic insights. m Heart J 1987;1 14: Gillam LD, Homma S, Novick SS, Rediker DE, Eagle K. The influence of heart rate on Doppler mitral inflow patterns [abstract]. Circulation 1987;76 (suppl V): Herzog C, Elsperger KJ, Manoles M, Murakami M, singer R. Effect of atrial pacing on left ventricular diastolic filling measured by pulsed Doppler echocardiography [abstract]. J m ll Cardiol 1987;9 (suppl ): Smith S, Stoner JE, Russel E, Sheppard JM, ylward PE. Transmitral velocities measured by pulsed Doppler in healthy volunteers: effects of acute changes in blood pressure and heart rate. Br Heart J 1989;61: Stratton JR, Halter JB, Hallstrom P, Caldwell JH, Ritchie JL. mparative plasma catecholamine and hemodynamic responses to handgrip, cold pressor and supine bicycle exercise testing in normal subjects. J m ll Cardiol 1983;2: Walsh R. Sympathetic control of diastolic function in congestive heart failure. Circulation 199;82 (suppl ): Harrison MR, Clifton GD, Berk MR, Smith MD, DeMaria N. Effect of heart rate on Doppler indices of left ventricular diastolic filling in man [abstract]. J m ll Cardiol 199;15 (suppl ): Van Dam, Fast J, De Boo T, et al. Normal diastolic filling patterns of the left ventricle. Eur Heart J 1988;9: Pearson C, Janosik DL, Redd RR, Buckingham T, Blum R, Labovitz J. Doppler echocardiographic assessment of the effect of varying atrioventricular delay and pacemaker mode on left ventricular filling. m Heart J 1988;115: Oniki T, Hashimoto Y, Shimizu S, et al. Effect of changes in heart rate and atrioventricular delay on left ventricular filling. J Cardiovasc Technol 199;9: Wallmeyer K, Wann LS, Sagar KB, Kalbfleisch J, Klopfenstein HS. The influence of preload and heart rate on Doppler echocardiographic indexes of left ventricular performance: comparison with invasive indexes in an experimental preparation. Circulation 1986;74:181-6.