Congestive heart failure treated by the upgrade from VVI to DDD pacing

The case is presented of an elderly woman with normal left ventricular (LV) systolic function and VVI pacing complicated by severe congestive heart failure. The symptoms and findings of congestive heart failure became refractory to medical treatment and resolved with the upgrade of the VVI to a DDD system. Right heart catheterization during VVI pacing showed increased mean pulmonary capillary wedge and right atrial pressures both being normalized under DDD pacing. This case report illustrates the need to consider permanent physiological pacing in elderly patients, even in presence of normal LV systolic function, to ensure AV synchrony when the atrium can be paced, since diastolic LV dysfunction is quite common in these subjects.     

Preimplantation echo Doppler evaluation of VVI versus DDD pacing

This study was carried out to select before permanent pacemaker implantation patients with complete atrioventricular block (CHB) who would benefit best from DDD pacing, and to determine the optimal atrioventricular delay (AVD) for each of those patients. This was achieved with the aid of Doppler echocardiography. The effect of different AVDs on both the systolic and diastolic function of the normal and failing heart was also delineated in this study. METHODS: Thirty patients with CHB and normal sinoatrial function were selected, with no age or sex predilection. These patients were categorized into three equal groups: groups A, B, and C with normal left ventricular (LV) systolic and diastolic function, LV diastolic dysfunction, and LV systolic dysfunction, respectively. For each patient, systolic and diastolic function was calculated utilizing echo Doppler during CHB, temporary VDD pacing with different AVDs, and temporary VVI pacing with a rate matching that during VDD mode. Temporary VDD mode of pacing was performed utilizing a temporary bipolar ventricular lead for ventricular pacing and an esophageal lead for atrial sensing to trigger ventricular pacing. RESULTS: Qualitatively the most obvious change in the pattern of LV filling as AVD is increased in the three groups, is the earlier occurrence of active atrial filling A wave due to progressive approximation of the ECG P wave toward the previous QRS. As the AV interval is increased, the following changes occur: (a) A wave occurs progressively earlier with superimposition onto the early filling E wave resulting in a progressive increase in its velocity (VA), its FVI, and its percent atrial contribution (%AC); (b) the three times diastolic filling time (DFT), mitral valve opening to Q wave (MVO-Q), and closure (Q-MVC) progressively shorten; (c) since DFT decreases, less passive filling occurs early during diastole, thus E.FVI decrease with longer AV intervals; (d) the ratios VE/VA and FVI E/A decrease subsequently to the previous described changes. Compared to CHB, percent ejection fraction (% EF) was not significantly changed during VVI pacing. Percent EF increased significantly during VDD in comparison to VVI pacing modes. Percent EF was highest at optimal AVD and decreased as this AVD increased or decreased. The cardiac output (CO) increment during VDD in comparison to VVI pacing modes differed much among the three groups. In group A, a 10.29% increase in CO was seen when comparing VDD pacing (with optimal AVD) with that of VII one; in group B, this increment was much greater and reached 29.48%; in group C it reached 23.68%.(ABSTRACT TRUNCATED AT 400 WORDS)     

Relative importance of activation sequence compared to atrioventricular synchrony in left ventricular function

This study evaluated the relative hemodynamic importance of a normal left ventricular (LV) activation sequence compared to atrioventricular (AV) synchrony with respect to systolic and diastolic function. Twelve patients with intact AV conduction and AV sequential pacemakers underwent radionuclide studies at rest and Doppler echocardiographic studies at rest and during submaximal exercise, comparing atrial demand pacing (AAI) to sequential AV sensing pacing (DDD) and ventricular demand pacing (VVI). Studies at rest were performed at a constant heart rate between pacing modes, and the exercise study was performed at a constant heart rate and work load. Cardiac output was higher during AAI than during both DDD and VVI (6.2 +/- 1 vs 5.6 +/- 1 and 5.3 +/- 1 liters/min, p less than 0.05). LV ejection fraction was likewise higher during AAI (55 +/- 12 vs 49 +/- 11 vs 51 +/- 13, p less than 0.05). VVI with or without AV synchrony was associated with a paradoxical septal motion pattern, resulting in a 25% impairment of regional septal ejection fraction. In addition, LV contraction duration was more homogenous during AAI. Peak filling rate during AAI and VVI was higher than during DDD (2.86 +/- 1 and 2.95 +/- 1 vs 2.25 +/- 1 end-diastolic volume/s; p less than 0.05). During VVI, the time to peak filling was significantly shorter than during both AAI and DDD (165 +/- 34 vs 239 +/- 99 and 224 +/- 99 ms; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Usefulness of Doppler tissue imaging for the assessment of right and left ventricular myocardial function in patients with dual-chamber pacing.

The aim of the study was to evaluate by Doppler tissue imaging (DTI) the combined effects of atrio-ventricular (AV) delay and heart rate (HR) changes on global and segmental right (RV) and left (LV) ventricular diastolic function in 15 patients with dual-chamber pacemakers paced in the DDD mode. RV and LV inflow velocities and regional systolic and diastolic pulsed-wave (PW) DTI parameters were analyzed at four different pacing modes: (1) HR 70 beats/min, AV delay 125 ms; (2) HR 70 beats/min, AV delay 188 ms; (3) HR 89 beats/min, AV delay 125 ms; (4) HR 89 beats/min, AV delay 188 ms. For each pacing mode selected, RV diastolic filling velocities always prevailed over LV ones. As for RV and LV adaptation to the four different stimulation protocols, a higher paced rate and a prolonged AV delay caused across both the AV valves a decrease of E wave and of E/A ratios. The intersegmental comparison of PW-DTI parameters outlined that RV free wall exhibited significantly higher peak systolic (Sm) and early-diastolic (Em) wall velocities, and longer systolic ejection time. Considering separately RV and LV segmental physiology at the four programmed pacing modes, an increase in HR determined a progressive shortening of systolic ejection times in all the segments analyzed. Moreover, in each region the Em/Am ratio decreased with higher HR and longer AV delay. Conversely, Em encountered a progressive reduction in RV free wall, while remaining quite unchanged in all the LV regions. Both ventricles shared a similar pattern of global and regional adaptation to programmed HR and AV delay modifications, consisting in a progressive greater contribution of late diastole to ventricular filling at higher HR and more prolonged AV delay. However, at a regional level the right ventricle exhibited higher systolic and diastolic wall velocities than all left ventricular regions.     

Evaluation by pulsed Doppler echocardiography of the atrial contribution to left ventricular filling in patients with DDD pacemakers

To evaluate the significance of the left atrial (LA) contribution to left ventricular (LV) filling in cardiac pacing, LV inflow velocity was recorded with pulsed Doppler echocardiography in 20 patients with a DDD pacemaker. The pacemaker was programmed to atrioventricular (AV) sequential pacing with AV intervals of 50, 100, 150, 200 and 250 ms, and then to VVI pacing at a fixed rate of 70 beats/min. To evaluate the relative changes of LV filling volume in individual patients, the percent change in time-velocity integral of LV inflow velocity in each pacing mode was calculated as the ratio to that of AV sequential pacing with an AV interval of 150 ms. To estimate the degree of LA contribution to LV filling, the ratio of time-velocity integral during LA ejection phase to that during total LV filling phase was measured at the optimal AV interval. The percent LV inflow volume in AV sequential pacing was 74% for an AV interval of 50 ms, 87% for 100 ms, 98% for 200 ms and 90% for 250 ms. The percent LV inflow volume in VVI pacing was 72%. The percent LV inflow volume at AV intervals of 150 ms was significantly greater than that at an AV interval of 50, 100 and 250 ms, and in VVI pacing (p less than 0.05). The degree of LA contribution to LV filling showed a positive correlation with the percent increase of LV inflow volume with mode conversion from VVI to AV sequential pacing (p less than 0.005) and also with age (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Similar pattern of diastolic function adaptation of both ventricles to programmed atrioventricular interval modification in patients with DDD pacing.

OBJECTIVE: To evaluate both left ventricular (LV) and right ventricular (RV) diastolic performance adaptation to variable atrioventricular interval (AVI), in patients with DDD pacing for complete heart block and to investigate a possible interaction between LV and RV in this specific cohort of patients. METHODS: We studied 22 consecutive patients (mean age 65.2 +/- 14.3 years) who underwent DDD pacemaker implantation following admission for complete heart block. One day following implantation, patients were paced at 3 different pacing modes, under the same programmed heart rate and a different AVI (100, 150 and 200 ms respectively). Standard Doppler echocardiography of mitral and tricuspid valve inflow was performed to evaluate LV and RV diastolic function, during each pacing mode. RESULTS: Left ventricular and RV diastolic performance adaptation to variable AVI modifications was similar, showing a progressive increase of late diastolic filling velocities and a subsequent decrease of E/A wave ratios following AVI prolongation. A short AVI of 100 or 150 ms was associated with improved LV and RV diastolic filling dynamics. CONCLUSIONS: In elderly patients with complete heart block and unimpaired systolic function undergoing DDD pacemaker implantation, both ventricles share a similar pattern of diastolic function adaptation to AVI modifications and that might be the reflection of ventricular interaction under this specific pacing mode.     

Effects of variation of atrioventricular interval on left ventricular diastolic filling dynamics and atrial natriuretic peptide levels in patients with DDD pacing for complete heart block.

AIMS: This study was designed to evaluate the effect of variation of atrioventricular (AV) interval (AVI) on left ventricular (LV) diastolic function and ANP and c-GMP levels during DDD pacing in patients with complete AV block and normal systolic function. METHODS: The study population comprised 22 patients (mean age 65.2+/-14.3, 12 males) with complete AV block. All patients underwent complete Doppler echocardiography before implantation of a DDD-pacemaker. Twenty-four hours later, patients were paced for a period of 30 min, at three different AVIs (100 ms, 150 ms and 200 ms), at rest. During each pacing period, Doppler-derived LV diastolic indices were re-evaluated and ANP and c-GMP levels were reassessed. RESULTS: Overall comparison showed a significant progressive augmentation, from 200 ms to 100 ms AVI, in transmitral E/A wave ratio (from 0.53+/-0.13 to 0.90+/-0.25, P = 0.0005) and in LV filling time (from 0.33+/-0.05 to 0.40+/-0.06s, P = 0.0005), followed by a significant progressive reduction in ANP and c-GMP levels. An AVI of 100 ms or 150 ms was associated with improved diastolic indices and lower natriuretic peptides levels, compared with the longer AVI. CONCLUSION: Programmed AVI during DDD pacing affects LV diastolic performance and plasma ANP and c-GMP levels. The assessment of these parameters constitutes a useful modality for AVI optimization.     

超声心动图评价双腔起搏器不同房室间期设置时心功能变化

目的采用超声心动技术评价双腔起搏器设置不同房室间期（AVD）时的急性血流动力学和心脏收缩舒张功能改变。方法36例高度或Ⅲ度房室传导阻滞安装双腔起搏器的患者,在常规设置AVD和根据体表心电图优化设置AVD的情况下分别进行超声心动图检查。结果与常规设置AVD相比,AVD优化后左室舒张末期容积、左室每搏量、左室射血分数和心排量显著增加,左室充盈时间延长,二尖瓣血流速度时间积分显著增加,Tei指数显著减小。此外,AVD优化后组织多普勒指标室间隔、左室前壁、下壁基底段收缩期峰值速度（Sm）显著增高,左、右心室壁基底段舒张晚期峰值速度（Am）显著增高,右室游离壁基底段的Sm、舒张早期峰值速度和Am均显著高于左室壁各基底段。结论双腔起搏器最佳AVD设置能改善患者的血流动力学指标和心脏功能,这些变化可用超声心动图来评价。     

Ventricular interdependence in patients with dual-chamber pacing: a Doppler tissue imaging study

PURPOSE: To analyze pulsed-Doppler tissue imaging (DTI) of the right ventricular (RV) tricuspid annulus and left ventricular (LV) mitral annulus in patients paced in the DDD mode at three different pacing modes as compared with healthy subjects, and to investigate possible physiologic interaction between the RV and LV in this subgroup of patients. METHODS: We selected a population of 22 subjects with pacemakers (PM) for atrioventricular (AV) block and/or sick sinus syndrome and compared them to 20 healthy subjects. Standard echo Doppler and DTI parameters were measured at baseline (heart rate [HR] 70 beats/min; AV delay 125 msec) and after at least 5 minutes of constant stimulation at two different pacing modes: (1) HR 70 beats/min, AV delay 188 msec, and (2) HR 89 beats/min, AV delay 125 msec. LV stroke volume was obtained by LV outflow Doppler method. RESULTS: In the PM group, RV and LV annulus exhibited significantly higher peak systolic (S(m)) and early (E(m)) diastolic wall velocities than controls. In the PM population, LV stroke volume was strongly associated to RV E(m) peak velocity (r = 0.83; P < 0.00001) and RV S(m) peak velocity (r = 0.81; P < 0.0001). These associations between LV stroke volume and RV DTI parameters remained significant even after increase of HR and AV delay in the pacing modalities. Moreover, univariate relations were found in the PM group between DTI indexes of RV tricuspid annulus and the homologous indexes of LV mitral annulus. In a multiple linear regression analysis, both RV E(m) (P < 0.001) and RV S(m) (P < 0.001) were related independently to LV stroke volume (cumulative R(2) = 0.85, P < 0.00001). CONCLUSIONS: Our findings suggest the usefulness of pulsed-DTI to display physiologic ventricular interaction in patients with PM. Therefore, DTI may be taken into account as a valuable supporting tool to predict LV systolic performance and to select the most appropriate pacing mode in individual PM patients.     

Effects of right ventricular pacing rate on the pattern of left ventricular contraction and filing as assessed by radionuclide ventriculography

Changes in the pattern of the global left ventricular (LV) time-activity curve with increasing pacing rates were evaluated using radionuclide ventriculography in 15 patients with chronically implanted right ventricular VVI pacemakers. The variables obtained were correlated with the conventional systolic time intervals recorded immediately after radionuclide ventriculography in 8 of the 15 patients. Increasing the pacing rate from 50 to 110 beats per minute (bpm) altered the pattern and timing of LV contraction and filling dramatically. It produced progressive delay and reduction of LV contraction, thus shortening the LV diastolic filling time, and sometimes resulting in LV filing even during early systole. Despite these profound alterations, relative cardiac output increased progressively, peaking at a pacing rate of 110 bpm in most patients. In paced patients, filling parameters and diastolic timing intervals require careful attention, since they may be difficult to determine from the altered LV time-activity curve at higher pacing rates.     

Effect of left bundle branch block on systolic and diastolic function of left ventricle in heart failure

This study was designed to examine the effect of left bundle branch block (LBBB) on systolic and diastolic function of the left ventricle (LV) in patients with heart failure and in normal subjects. Thirty-six patients with heart failure and LBBB (group I), 36 patients with heart failure with normal conduction (group II), and 41 subjects with isolated LBBB (group III) were compared. Coronary angiography was performed and LV end diastolic pressure was calculated. Echocardiography was performed on all patients. LV ejection fraction and mean rate of circumferential shortening were calculated. The following Doppler parameters were evaluated: peak rapid filling velocity (E wave), peak atrial filling velocity (A wave), E- and A-wave integrals, E-wave acceleration time and deceleration time (EDT) and rates (EAR and EDR), the E/A ratio and its integral, and diastolic flow time (DT). The ejection time, isovolumetric relaxation time (IRT), and preejection period were measured using the aortic and mitral flow. LV end diastolic pressure was calculated as 28 +/- 4 mm Hg, 22 +/- 5 mm Hg, and 15 +/- 3 mm Hg in groups I, II, and III, respectively. Although the systolic function parameters in group III patients were different, the diastolic function parameters of group II were found to be quite similar to those of group III patients. Comparison of group I patients with group II patients showed that there was a similarity between LV systolic function parameters while the diastolic function parameters were different (E/A, p = 0.004; EAR, p < 0.001; EDR, p < 0.001; EDT, p < 0.001; IRT, p = 0.024; DT, p = 0.03). In conclusion, this study evaluating the effects of LBBB in normal subjects (isolated LBBB) and patients with heart failure showed that LBBB causes diastolic function impairment in normal subjects similar to those of patients with heart failure, and also increases impairment of diastolic function in patients with heart failure.     

实时三维超声心动图评价永久起搏患者左心室收缩同步性和心功能

目的 探讨应用实时三维超声心动图(RT-3DE)评价永久起搏患者左心室收缩同步性和心功能.方法 15例病态窦房结综合征置入双腔起搏器患者,分别将起搏模式程控为心房抑制型按需起搏(AAI)、房室按需型起搏(DDD)、心室抑制型按需起搏(VVI),每种起搏模式稳定5 min后,在RT-3DE下取左心室全容积图像.应用Qlab4.2脱机分析软件,获得左心室整体与17节段容积-时间曲线和比较左心室16、12、6节段心电图QRS波起点至左心室最小容积点时间的标准差和最大时间差(即Tmsv16-s、Tmsv12-s、Tmsv6-s、Tmsv16-dif、Tmsv12-dif、Tmsv6-dif)、左心室舒张末期容积、左心室收缩末期容积、左心室射血分数、左心室舒张早期峰值充盈率、左心室17节段的舒张末期容积、收缩末期容积和节段射血分数.结果 心室同步性指标容积-时间曲线和Tmsv16-s、Tmsv12-s、Tmsv6-s、Tmsv16-dif、Tmsv12-dif、Tmsv6-dif在AAI模式明显优于DDD、VVI模式(P<0.05),心功能指标左心室射血分数、左心室舒张早期峰值充盈率在AAI模式下显著高于DDD和VVI模式(P<0.05);DDD和VVI模式的上述指标差异无统计学意义(P>0.05);DDD与VVI模式时左心室前间隔、下壁和后壁基底段、心尖段节段射血分数较AAI模式明显降低(P<0.05).结论 采用RT-3DE可客观准确地评价永久起搏患者左心室收缩同步性和心功能.     

生理性双腔起搏时最佳AV间期选择与心功能关系的探讨

对 2 0例心肌病心力衰竭 (简称心衰 )患者 (心衰组 )及 10例心功能正常者 (对照组 )行双腔 (DDD)起搏治疗 ,探讨不同AV间期DDD起搏对心衰患者的急性血液动力学效应。经锁骨下静脉置入双腔起搏电极 ,并同时置入Swan Ganz导管 ,测量不同AV间期的急性血液动力学效应 ,二维超声多普勒测量超声形态学指标。结果 :急性起搏时心衰组AV间期在 10 0～ 140ms时 ,血液动力学较起搏前显著改善 ,而以AV为 111± 15ms为最佳。左室舒张末径、左室收缩末径、左房内径显著缩小 ,收缩期二尖瓣返流减轻 ,未发现舒张期二尖瓣返流。而对照组AV间期为16 0～ 180ms时 ,上述指标与起搏前相比显著改善。结论 :短AV间期的生理性起搏能即刻改善心衰患者的急性血液动力学效应和超声形态学指标。     

Hemodynamic comparison of ventricular pacing, atrioventricular sequential pacing, and atrial synchronous ventricular pacing using radionuclide ventriculography

To assess the hemodynamic effects of physiologic pacing, 13 patients with DDD pacemakers who had varying degrees of atrioventricular (AV) block were studied with radionuclide ventriculography during VVI, DVI and VDD modes. Radionuclide ventriculography was performed with patient in the supine position at rest 5 to 10 minutes after the pacing mode and AV delay were changed. The AV delays selected were short (mean 147 +/- 4.8 ms) and long (mean 197 +/- 4.8 ms), with a constant difference of 50 ms. During VVI, 6 patients (group 1) had a left ventricular ejection fraction of 40% or less (mean 22 +/- 11) and 7 patients (group 2) had an ejection fraction of more than 40% (mean 59 +/- 11). Comparisons of ejection fraction, end-diastolic volume and cardiac index between VVI and both modes of AV pacing (VDD and DVI) and between long and short AV delays led to the following conclusions: DVI or VDD pacing produces more beneficial hemodynamic effects than VVI, and these effects are more pronounced in patients with low ejection fraction if longer AV delay is used. The VDD mode significantly improves ventricular function over the DVI mode in patients with an ejection fraction of more than 40% independent of heart rate. Longer AV delay is essential in patients with an ejection fraction of 40% or less to improve ventricular function with physiologic pacing.     

Assessment of right ventricular diastolic filling in patients with coronary artery disease

To assess right ventricular (RV) diastolic filling in coronary artery disease (CAD), with special reference to the involved lesions of the coronary arteries and left ventricular (LV) systolic function, gated radionuclide ventriculography was performed at rest in 106 patients with single-vessel CAD. Based on the site of coronary arterial involvement, patients were classified into three groups: left anterior descending CAD, right CAD, and left circumflex CAD. Patients in each group were further subdivided according to normal or decreased LV ejection fraction, resulting in six groups. Seventeen normal subjects were examined as a control group. Tune-activity and its first-derivative curves were computed for the right and left ventricles. RV systolic function was normally preserved in all six groups, even when LV systolic function was damaged severely. The ratio of peak RV filling rate to peak RV ejection rate was significantly decreased in all six groups compared with that in control subjects, indicating that RV filling was impaired in patients with CAD. The ratio was below the lower limit of normal in 14 (23%) of 62 patients with normal LV systolic function and in 13 (30%) of 44 patients with impaired LV systolic function. None of the control subjects showed a decreased ratio of peak RV filling rate to peak RV ejection rate. Thus, in patients with CAD, RV filling is impaired, which may be independent of the site of coronary arterial involvement and of the LV or RV systolic function.     

Assessment of the optimal atrio-ventricular delay in DDD paced patients by impedance plethysmography

The beneficial haemodynamic effects of sequential atrioventricular(AV) pacing have been clearly established and are dependenton the AV delay and pacing rate. However, the optimal AV delayis difficult to determine in each particular patient. We useda modified impedance plethysmographic method to assess variationsin stroke volume for different AV delay and pacing rate settings.Impedance measurements showed a good correlation with CO₂ rebreathingstroke volume measurements in VVI patients. Impedance variationswere then used to set the optimal AV delay at different pacingrates in DDD patients. The inverse relationship between theoptimal AV delay and the pacing rate has been accurately identifiedin most of the patients but is not predictable. In all cases,the cardiac output was higher in DDD mode at the optimal AVdelay than in VVI mode. In some patients with a damaged myocardium,the stroke volume appeared to be highly sensitive to multipleA V delay settings. Impedance plethysmography can permit suchrepetitive non-invasive quick measurements, increasing the accuracyof optimal A V delay determination and is well suited for routineexamination of patients with cardiac dual chamber pacemakers     

Left ventricular performance at rest and during exercise in patients with dual-chamber pacemakers.

In 13 patients with an implanted dual-chamber atrioventricular (AV) demand pacemaker, left ventricular performance was elicited by pacing mode manipulation for study using gated cardiac pool scintigraphy at rest and during exercise. There was no significant difference between DDD and VVI at 70 and 90 beats/min with respect to cardiac output, peak ejection rate or peak filling rate. At 110 beats/min, the cardiac output was greater with DDD as compared to VVI. The peak filling rate was also significantly greater with DDD as compared to VVI (DDD: 3.6 vs VVI: 2.8 EDV/s, p less than 0.05). During exercise the cardiac output was greater with DDD as compared to VVI at the same rate. The peak filling rate during exercise was significantly greater with DDD as compared to VVI (DDD: 3.0 vs VVI: 2.5 EDV/s, p less than 0.01). We conclude that DDD is more beneficial than VVI in maintaining cardiac performance during exercise.     

CRT治疗慢性心衰的临床观察

目的观察心脏再同步化治疗(CRT)慢性心力衰竭(CHF)患者的临床疗效。方法选择2006年5月～2009年4月植入CRT起搏器的患者8例,其中7例为窦性心律;1例为房颤。优化AV间期及/或VV间期等参数,随访10.1±8.9个月,观察患者心功能改善情况、QRS波时限改变和左室射血分数(LVEF)、左室舒张末内径(LVEDD)、二尖瓣返流及左/右心室不同步等心脏超声参数的变化。结果所有8例患者植入CRT起搏器后,心功能分级与LVEF提高,临床症状明显减轻,6分钟步行距离增加,QRS波时限、LVEDD及MR减少,左/右心室不同步明显改善,心衰平均住院时间减少约33%(p0.05);1例患者CRT植入后13个月发生VT/VF猝死。结论CRT可明显改善CHF患者的心功能,缓解临床症状并提高生活质量;对可能发生VT/VF的高危CHF患者,置入CRT(D)可预防心源性猝死。     

Non-invasive study of dual chamber pacing by pulsed Doppler. Prediction of the haemodynamic response by echocardiographic measurements

The increase in stroke volume with DDD compared with VVI pacingwas measured at rest using pulsed Doppler echocardiography in23 patients at a pacing rate of 70 beats min^–1. Strokevolume was assessed by measuring the velocity integral of theflow at the level of the aortic annulus using the apical five-chamberwindow. Pulsed Doppler echocardiography allowed determinationof the least and most favourable A V delay haemodynamically.TVI was also measured at each nominal value of AV delay. The percentage increase in stroke volume was determined in everypatient changing from VVI to optimum DDD pacing and was usedas a measurement of the ‘sensitivity’ to optimumDDD pacing; the mean increase was 27 ±19%. The increasein stroke volume accompanying the change from DDD pacing withthe least favourable to the optimum A V delay was also measured,and used as a measurement of ‘sensitivity’ to changesin A V delay; the mean increase was 23.7 ± 16.3%. Clinicaland standard echocardiographic parameters were studied in orderto determine which variable might best identify the patientsmore likely to benefit from DDD pacing, and to identify thosemore sensitive to the A V delay setting. With respect to sensitivityto DDD pacing, three echocardiographic variables were selectedby linear discriminant analysis from 11 clinical and echocardiographicvariables. These were, in order of importance, left ventricularsystolic diameter (LVSD), left ventricular wall thickness (LVWT)and left atrial size (LAS) which allowed the prediction of agood or a bad response to optimal DDD pacing with an accuracyof 91–3%. The discriminant values between responders (morethan 25% increase in TVI) and non–responders (less than25% increase) were 36.4mm (LVSD), 10.1 mm (LVWT) and 35.8 mm(LAS) respectively. With respect to sensitivity to changes inA V delay, the best predictive parameter was left ventriculardiastolic diameter (LVDD), which gave a predictive accuracyof 87.5%.     

The effect of different atrioventricular delays on left atrium and left atrial appendage function in patients with DDD pacemaker

Background: Although it has been known that optimization of atrioventricular delay (AVD) has favorable effect on the left ventricular functions in patients with DDD pacemaker, the effect of different AVDs on left atrium (LA) and left atrial appendage (LAA) functions has not been exactly evaluated. The aim of the present study was to assess the effect of different AVDs on LA and LAA functions in DDD pacemaker implanted patients with atrioventricular block. Methods: Forty‐eight patients with DDD pacemaker were enrolled into the study. Patients were divided into two groups according to the echocardiographic diastolic function: Group I (normal diastolic function) and Group II (diastolic dysfunction). LAA emptying velocity on pulsed wave Doppler and LAA late systolic wave velocity by using tissue Doppler were recorded. Patients were paced for five successive continuous pacing periods of 10 minutes duration using five selective AVDs (80–250 ms). Results: Significant effect on LA and LAA functions has not been observed by the setting of AVD in Group I. However, when the AVD was gradually shortened form 150 ms to 80 ms, LA and LAA functions gradually decreased in Group II patients. When AVD increased to 200 ms, LA and LAA functions were improved. Further increase in AVD resulted in decreased LA and LAA functions. Conclusion: Setting of AVD has not significant effect on the LA and LAA functions in patients with normal diastolic function, but moderate prolongation of AVD in physiological limits improved LA and LAA functions in DDD pacemaker implanted patients with diastolic dysfunction. (Echocardiography 2011;28:626‐632)