Hemodynamic effects of acute atrioventricular sequential pacing in patients with left ventricular dysfunction

Acute atrioventricular (A-V) sequential pacing was compared with ventricular pacing in seven men with symptomatic left ventricular failure (New York Heart Association functional class III and IV) and depressed left ventricular ejection fraction (mean 29 percent, range 18 to 40). Cardiac index was higher during A-V sequential pacing than during ventricular pacing for every patient at paced rates of 75 to 100 beats/min. The mean increment was 17 percent (range 10 to 37) at a paced rate of 75 beats/ min, 23 percent (range 8 to 45) at a paced rate of 85 beats/min and 29 percent (range 19 to 55) at a paced rate of 100 beats/min. The increase in cardiac index in an individual patient did not correlate with baseline characteristics including functional class, cardiothoracic ratio, resting ejection fraction, cardiac index or balloon-occluded pulmonary wedge pressure.Arterial pressure varied from beat to beat during ventricular pacing because of the changing relation of atrial to ventricular systole. When an atrial contraction preceded a ventricular paced beat by a physiologic interval intraarterial pulse pressure uniformly increased. That increase correlated strongly (r = 0.993) with the increase in cardiac index that occurred during A-V sequential pacing. Measurement of the pulse pressure during A-V dissociation is a simple technique that may be useful for predicting the degree of improvement in cardiac output expected with methods of pacing that restore A-V synchrony.     

Importance of left ventricular function and systolic ventricular interaction to right ventricular performance during acute right heart ischemia.

To determine whether modulation of systolic ventricular interaction influences right ventricular performance during right heart ischemia, the effects of septal ischemia and inotropic stimulation were studied in 15 dogs in an open chest preparation. Right coronary branch occlusions led to right ventricular dilation and free wall dyskinesia, reversed septal curvature and reduced left ventricular diastolic volume. In systole, the septum thickened but bulged paradoxically into the right ventricle generating an active but depressed right ventricular systolic pressure (28.9 +/- 5.5 to 22.1 +/- 4.5 mm Hg), with associated decreases in right ventricular stroke work (5.66 +/- 0.94 to 1.92 +/- 0.53 g.m/m2) and left ventricular systolic pressure (123 +/- 11 to 80 +/- 10 mm Hg). Septal ischemia induced systolic septal thinning, left ventricular dilation and decreased left ventricular systolic pressure (80 +/- 10 to 55 +/- 10 mm Hg) and stroke work. Although the extent of paradoxic septal displacement increased, there were further decrements in right ventricular systolic pressure (22.1 +/- 4.5 to 18.7 +/- 4.3 mm Hg) and stroke work (1.92 +/- 0.53 to 0.7 +/- 0.2 g.m/m2). Dopamine infusion augmented left ventricular free wall contraction and increased left ventricular systolic pressure (55 +/- 10 to 172 +/- 17 mm Hg) and stroke work. Although systolic septal thinning persisted, the extent of paradoxic septal displacement increased strikingly and, despite continued right ventricular free wall dyskinesia, right ventricular systolic pressure increased (18.7 +/- 4.3 to 39.6 +/- 6.2 mm Hg) as did right ventricular stroke work (0.7 +/- 0.2 to 7 +/- 1.6 g.m/m2).(ABSTRACT TRUNCATED AT 250 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)     

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.     

Three-dimensional guided selective right ventricular septal pacing preserves ventricular systolic function and synchrony in pediatric patients

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心脏右侧DDD起搏对心功能和心室收缩同步性的影响

目的 用平衡法核素心室显像（equilibrium　radionuclide　angiography,ERNA）方法评价心脏右侧DDD起搏对心功能和心室同步性的影响。方法10例病态窦房结综合征或间歇二度房室阻滞患者植入DDD起搏器。患者植入起搏器后行ERNA检查,用程控仪调整起搏器参数,分别在起搏情况下和窦性心律情况下采集数据,通过半自动处理数据获得心功能参数,对采集的数据进行位相分析（Phase analysis）处理,了解心室激动顺序,计算出相角程（Phase　shift）来评估心室激动的同步性。结果患者在起搏时,左心室1/3EF比窦性心律时明显减低[（0.23±0.06）对（0.28±0.05）,P=0.01]。位相分析显示起搏时右心室激动早于左心室,相角程增宽[（64.13±16.81）°对（52.88±9.26）°,P=0.007]。在窦性心律时心室激动顺序为从室间隔近端或左心室基底部向心尖方向扩散,起搏心律时心室激动顺序发生改变,从右心室心尖部向心底部和左心室扩散。结论 单纯右心室起搏增加心室不同步性,影响左心室收缩功能。     

Dual-site right ventricular and left ventricular pacing in a patient with left ventricular systolic dysfunction and atrial fibrillation using a standard CRT-D device

In patients undergoing cardiac resynchronization therapy with defibrillator (CRT-D) implantation for left ventricular systolic dysfunction (LVSD) accompanied by permanent atrial fibrillation (AF), generally, the unused atrial port is plugged at device implantation. We describe an alternative use for the atrial-port in this case report.A 43 year old gentleman with LVSD due to left ventricular non-compaction (LVNC) and AF of unknown duration underwent a CRT-D implantation after optimization of cardiac failure treatment. The atrial-port which would otherwise have been plugged was connected to a high right ventricular septal (RVS) pacing-lead and the shock-lead was positioned at the right ventricular apex (RVA). This approach permitted modified cardiac resynchronization in a high RVS to left ventricular (LV) and RVA pacing sequence using the high RVS and LV pacing combined with a shock vector including the RV apex. A standard CRT-D device with a minimum programmable A–V delay of 30 ms (technically RVS to LV delay in the ‘DDD’ pacing mode) was used. The device was programmed to a ‘DDD’ pacing mode (sequential multi-site ventricular pacing with some programmability). The mode switch operation was programmed ‘OFF’ since atrial sensing is unavailable. Device-delivered shocks did not cardiovert the patient back to sinus rhythm suggesting that the AF was permanent (no prior cardioversion attempts were made on the presumption that the chances of maintaining sinus rhythm, given the underlying cardiac condition, were low). Subsequently, the patient required radio-frequency ablation of the atrio-ventricular node for conducted AF. Symptomatic, echocardiographic and radiological improvement preceded atrio-ventricular node ablation.ConclusionAmongst AF patients with permanent AF undergoing CRT-D implantation, those patients who are likely to have the CRT-D device atrial-ports plugged could benefit from having both the options of (i) a RVA shock vector as well as (ii) a high RVS-pacing feasible, by utilizing the atrial-port of a conventional CRTD device for a RVS pacing lead, should a RVA shock-lead position be preferred. New device programming algorithms will be necessary to make patient-customized programming in this lead configuration flexible, more useful clinically and easy.     

Potentiation of atrial contractility by paired pacing augments ventricular preload and systolic performance

BACKGROUND: Paired electrical stimulation and postextrasystolic potentiation (PESP) of contractility has been extensively studied in ventricular myocardium, but less is known about PESP of atrial contractility. Our aim was to determine whether PESP of atrial contractility could augment left ventricular (LV) preload and improve LV systolic performance. METHODS AND RESULTS: A paired electrical stimulus closely following the pacing stimulus was applied to isolated atrial and ventricular myocardium from 4 dog hearts, and the interval dependent force potentiation was examined. In isolated atrial myocardium, paired pacing increased the active tension from a baseline of 1.36 +/- 0.23 to 2.60 +/- 0.57 g/mm(2); in ventricular myocardium active tension increased from 2.58 +/- 0.42 to 3.81 +/- 0.27 g/mm(2) (both P <.01). Then, LV pressure (micromanometer) and segment length (ultrasonic crystals) were measured in the intact hearts of 7 anesthetized dogs in which premature stimuli were applied to the atrium. In intact hearts, paired pacing of the atrium (coupling interval 200 ms) increased LV end-diastolic pressure from 3.8 +/- 1.0 to 6.4 +/- 1.0 mm Hg; systolic pressure increased from 105 +/- 6 to 112 +/- 7 mm Hg (both P <.05). LV pressure-length loop area (regional stroke work) increased 10.5 +/- 0.2%. CONCLUSIONS: Isolated atrial myocardium exhibits substantial PESP of contractility, which is similar to ventricular myocardium. In the intact heart, atrial PESP augments LV systolic performance by effecting an increase in LV preload. This technique may provide a means of improving cardiac performance in patients with heart failure.     

High prevalence of right ventricular systolic dysfunction in early systemic sclerosis

OBJECTIVE: To assess right ventricular (RV) function in patients with early systemic sclerosis (SSc) and the acute effects of calcium channel blockers on RV ejection fraction (RVEF). METHODS: Forty-two consecutive patients with SSc with less than 5 years' disease duration and normal pulmonary arterial pressure (35 women, 7 men; mean age 54.3 +/- 9.7 years; 16 with diffuse and 26 with limited cutaneous forms, systolic pulmonary arterial pressure 30.3 +/- 5.4 mmHg) were prospectively evaluated. All underwent pulmonary function testing, echocardiography, and radionuclide ventriculography at rest and 2 hours after receiving 40 mg oral nicardipine, and were compared at baseline with 20 gender and age matched controls. RESULTS: None of the patients with SSc had clinical evidence of heart failure. At baseline, SSc patients had significantly lower LVEF (68.5% +/- 7.9 vs 72.4% +/- 5.0, p = 0.049) and RVEF (36.5% +/- 7.0 vs 45.8% +/- 5.7, p < 0.0001). Sixteen patients had reduced RVEF (< 35%), 3 had reduced LVEF (< 55%), and 10 had reduced peak filling rate (PFR). RVEF correlated to both LVEF and PFR (r = 0.64, p < 0.0001, and r = 0.36, p = 0.0037, respectively), whereas no correlation was found with pulmonary function impairment or pulmonary arterial pressure. Nicardipine resulted in a significant increase in RVEF (from 36.5% +/- 7.0 to 42.3% +/- 8.4, p < 0.001) whereas afterload indicated by mean arterial pressure did not differ significantly. CONCLUSION: Reduced RVEF appears to be a common feature in early SSc; it may be due to intrinsic myocardial involvement and is acutely improved by nicardipine.     

右室高位室间隔与心尖部起搏对心室收缩同步性和心功能的影响

目的探讨右室高位室间隔(HRVS)与右室心尖部(RVA)起搏对心室收缩同步性和心功能的影响及其机制,为右室高位室间隔起搏的临床应用提供理论基础。方法将具有行永久性双腔心脏起搏器植入术指征的77例患者,根据心室起搏电极植入部位的不同,随机分为HRVS起搏组(40例)和RVA起搏组(37例)。分别于术前、术后3个月和术后18个月,通过询问病史、查体、心电图和超声心动图检查对患者的一般临床状况、QRS波群时限(QRSd)、左右室射血前时间差值(LRVPEI)、室间隔与左室后壁收缩延迟时间(SPWMD)、左室射血分数(LVEF)进行观察随访。同时运用起搏器程控仪对患者术后3个月和18个月的起搏房室间期、心室起搏比例等起搏相关参数进行监测和调控。最后对两组患者的上述指标进行对比研究和统计学分析。结果两组患者一般临床特征及术前各项观察指标均无明显差别。术后3个月时,两组患者起搏相关参数均无显著差别(P<0.05),△HRVS起搏组的△QRSd、△LRVPEI和△SPWMD均明显小于RVA起搏组(P<0.05),LVEF无显著差别(P<0.05)。术后18个月时,两组患者间起搏相关参数没有明显差别,△QRSd、△LRVPE...     

Regional right ventricular dysfunction in acute pulmonary embolism and right ventricular infarction.

BACKGROUND: A normally contracting right ventricular apex associated to a severe hypokinesia of the mid-free wall ('McConnell sign') has been considered a distinct echocardiographic pattern of acute pulmonary embolism. OBJECTIVE: To evaluate the clinical utility of the 'McConnell sign' in the bedside diagnostic work-up of patients presenting to the Emergency Department with an acute right ventricular dysfunction due to pulmonary embolism or right ventricular infarction. DESIGN: Among 201 patients, consecutively selected from our clinical database and diagnosed as having massive or submassive pulmonary embolism or right ventricular infarction, 161 were suitable for an echocardiographic review of regional right ventricular contraction and were included in the study. There were 107 cases with pulmonary embolism (group 1) and 54 cases with right ventricular infarction (group 2). All echocardiographic studies were randomly examined by two experienced and independent echocardiographers, blinded to the patient diagnosis and without Doppler informations. RESULTS: The McConnell sign was detected in 75 of 107 patients in group 1 (70%) and in 36 of 54 patients in group 2 (67%); the finding was absent in 32 cases in group 1 and in 18 cases in group 2 (P=0.657). The sensitivity, specificity, positive and negative predictive values of the McConnell sign for the diagnosis of pulmonary embolism were respectively 70, 33, 67 and 36%. CONCLUSIONS: In a clinical setting of patients with acute right ventricular dysfunction the McConnell sign cannot be considered a specific marker of pulmonary embolism.     

Plasma B-type natriuretic peptide levels in systolic heart failure: importance of left ventricular diastolic function and right ventricular systolic function

OBJECTIVES: This study was designed to characterize the importance of echocardiographic indexes, including newer indexes of diastolic function, as determinants of plasma B-type natriuretic peptide (BNP) levels in patients with systolic heart failure (SHF). BACKGROUND: Plasma BNP levels have utility for diagnosing and managing heart failure. However, there is significant heterogeneity in BNP levels that is not explained by left ventricular size and function alone. METHODS: In 106 patients with symptomatic SHF (left ventricular ejection fraction [LVEF] <0.35), we measured plasma BNP levels and performed comprehensive echocardiography with assessment of left ventricular diastolic function, including color M-mode (CMM) and tissue Doppler imaging (TDI), and of right ventricular (RV) function. RESULTS: Median plasma BNP levels were elevated and increased with greater severity of diastolic dysfunction. We found significant correlations (p < 0.001 for all) between BNP and indexes of myocardial relaxation (early diastolic velocity: r = -0.26), compliance (deceleration time: r = -0.55), and filling pressure (early transmitral to early annular diastolic velocity ratio: r = 0.51; early transmitral flow to the velocity of early left ventricular flow propagation ratio: r = 0.41). In multivariate analysis, overall diastolic stage, LVEF, RV systolic dysfunction, mitral regurgitation (MR) severity, age and creatinine clearance were independent predictors of BNP levels (model fit r = 0.8, p < 0.001). CONCLUSIONS: Plasma BNP levels are significantly related to newer diastolic indexes measured from TDI and CMM in SHF. Heterogeneity of BNP levels in patients with SHF reflects the severity of diastolic abnormality, RV dysfunction, and MR in addition to LVEF, age, and renal function. These findings may explain the powerful relationship of BNP to symptoms and prognosis in SHF.     

Usefulness of echocardiographic right ventricular measurements in estimating right ventricular hypertrophy and right ventricular systolic pressure

Right ventricular wall thickness (T) measurements were made in 111 patients by echocardiography to evaluate their usefulness in diagnossing right ventricular hypertrophy (RVH) and in predicting right ventricular peak systolic pressure (P). Anatomic and echocardiographic findings of RVH were compared in 36 of 111 subjects: diastolic T (dT) and systolic T (sT) had a sensitivity of 90 and 34% and a specificity of 94 and 100%, respectively, in the diagnosis of RVH. Echocardiographic and hemodynamic findings were compared in the remaining 75 of 111 patients undergoing cardiac catheterization: dt was 6.5 +/- 2.7 mm in 46 patients with elevated P (58.2 +/- 30.2 mm Hg) versus 3.8 +/- 0.9 in 29 patients with normal P (26.3 +/- 2.7 mm Hg) (p less than 0.01). The dT and P had a linear correlation (r = 0.92) in 40 patients with right ventricular end-diastolic dimension less than 13 mm/m2. Estimates of P in 22 patients with atrial septal defect and right ventricular end-diastolic dimension greater than 13 mm/m2 were fairly good (r = 0.83). It is concluded that echocardiographic measurements of T are useful in diagnosing RVH and in estimating P.