Coronary and left ventricular pacing as standby in invasive cardiology.

Coronary pacing using as unipolar negative electrode a guidewire placed in a coronary branch was tested in 349 sites of 300 consecutive patients undergoing coronary angioplasty. It was possible for 339 sites (97%). The threshold currents ranged from 1 to 15 (mean +/- standard deviation 3.4 +/- 2.4) mA. Side effects were seen in 13 patients (4%): 6 (2%) had transient coronary spasm, 4 (1%) had diaphragmatic stimulation, and 3 (1%) had stinging pain at the skin electrode. Of the 10 cases with pacing failure, left ventricular pacing was successfully tested in 5 by introducing the coronary wire or another wire into the left ventricle. It yielded a threshold of 2-8 (3.2 +/- 2.7) mA. Therapeutic pacing for significant bradycardia was required in 7 patients (2%). It was successful in all. Coronary or left ventricular pacing appears to be a simple and reliable temporary measure. When there is no wire in the coronary artery or for diagnostic catheterization, left ventricular pacing can be done using the same setup and any type of guidewire.     

Coronary and left ventricular pacing as standby in invasive cardiology

Coronary pacing using as unipolar negative electrode a guidewire placed in a coronary branch was tested in 349 sites of 300 consecutive patients undergoing coronary angio-plasty. It was possible for 339 sites (97%). The threshold currents ranged from 1 to 15 (mean ± standard deviation 3.4 ± 2.4) mA. Side effects were seen in 13 patients (4%): 6 (2%) had transient coronary spasm, 4 (1%) had diaphragmatic stimulation, and 3 (1%) had stinging pain at the skin electrode. Of the 10 cases with pacing failure, left ventricular pacing was successfully tested in 5 by introducing the coronary wire or another wire into the left ventricle. It yielded a threshold of 2–8 (3.2 ± 2.7) mA. Therapeutic pacing for significant bradycardia was required in 7 patients (2%). It was successful in all. Coronary or left ventricular pacing appears to be a simple and reliable temporary measure. When there is no wire in the coronary artery or for diagnostic catheterization, left ventricular pacing can be done using the same setup and any type of guidewire.     

Effect of optimizing the VV interval on left ventricular contractility in cardiac resynchronization therapy

Simultaneous biventricular pacing improves left ventricular (LV) function in patients with heart failure and LV asynchrony. Proper timing of the interventricular pacing interval (VV interval) may further optimize LV function. We investigated the acute hemodynamic response of changing the VV interval using maximum LV dP/dt (LV dP/dt_max) as a parameter for LV function. A biventricular pacemaker was implanted in 53 patients with severely impaired LV function, New York Heart Association class III and IV heart failure, left bundle branch block, LV asynchrony, and a QRS interval >150 ms. Optimization of the atrioventricular and VV intervals was based on measurement of LV dP/dt_max by a 0.014-in sensor-tipped pressure guidewire. Measurement of LV dP/dt_max was obtained without complications in all patients. In patients in sinus rhythm with ischemic cardiomyopathy or idiopathic dilated cardiomyopathy, mean improvements by simultaneous biventricular pacing were 17% and 18%, respectively. Patients in atrial fibrillation showed an improvement of 21%. Optimizing the VV interval resulted in further absolute increases of 8%, 7%, and 3%, respectively, in dP/dt_max in the 3 groups. Maximum dP/dt was achieved with LV pacing first in 44 patients, simultaneous right and left ventricular pacing in 6 patients, and right ventricular pacing first in 3 patients. The mean optimal VV intervals were 37 ± 32 ms in the atrial fibrillation group, 28 ± 30 ms in the idiopathic dilated cardiomyopathy group, and 52 ± 31 ms in the ischemic cardiomyopathy group. Optimization of the VV interval significantly increased LV dP/dt_max compared with simultaneous biventricular pacing, and such optimization could be easily, accurately, and reliably evaluated by a 0.014-in sensor-tipped pressure guidewire.     

Temporary coronary guidewire pacing during percutaneous coronary intervention.

Temporary pacing is occasionally required during percutaneous coronary artery interventions. This can be accomplished by the insertion of a temporary transvenous pacemaker wire into the right ventricle, but there is some risk and inconvenience associated with this approach. Temporary pacing using the coronary artery guidewire was described in 1985 but is used infrequently. Using currently available equipment, we evaluated guidewire pacing in 26 patients. Guidewire pacing was successful in all patients, but not with all coronary guidewires at acceptable ventricular capture thresholds. No complications occurred from guidewire pacing. Bench testing of multiple different wires showed several with very high resistances likely unsuitable for clinical use. Temporary guidewire pacing is easily performed and should be considered as an alternative to the separate placement of a temporary transvenous pacemaker.     

Utility of a novel pacing guidewire in pre-implantation testing at different left ventricular sites in cardiac resynchronization therapy procedures

Purpose  

This study aimed to evaluate the utility of a novel pacing guidewire in pre-implantation testing of different left ventricular (LV) sites during cardiac resynchronization therapy (CRT) procedures.     

Coronary pacing during percutaneous transluminal coronary angioplasty

To avoid venous puncture, a new concept for standby cardiac pacing during percutaneous transluminal coronary angioplasty (PTCA) and diagnostic cardiac catheterization was developed. It uses an arterial guidewire as a unipolar pacing electrode with the second electrode attached to the skin. The system was tested in 25 coronary arteries of 22 patients undergoing PTCA and in the left ventricles of 10 patients undergoing diagnostic cardiac catheterization. Coronary pacing via the guidewire used for directing the balloon catheter was possible in all patients and in 24 of the 25 coronary arteries attempted. Maximum duration of pacing was 8 min. Threshold currents ranged from 1 to 15 mA (mean 5.7). Left ventricular pacing via the same wires or standard wires used for introduction of diagnostic or guiding catheters was possible in all patients and was maintained for up to 10 min. Threshold currents ranged from 1 to 7 mA (mean 3.9). Neither method for pacing produced adverse effects during these short applications. The setup for coronary pacing also allowed recording of an intracoronary electrocardiogram during PTCA. The presented system provides backup for the rare event of sustained bradycardia during PTCA or diagnostic cardiac catheterization. If applied cautiously, it may safely and reliably replace the standby of a conventional transvenous pacing catheter.     

Detection of pacing-induced myocardial ischemia by endocardial electrograms recorded during cardiac catheterization

Rapid atrial pacing confirms myocardial ischemia in patients with coronary artery disease when angina is provoked, and is accompanied by an increase in left ventricular end-diastolic pressure. In such cases, abnormalities in the surface electrocardiogram (ECG) are often not apparent. To enhance detection of subendocardial ischemia during rapid atrial pacing, local unipolar electrograms were recorded from the tip of a 0.025 in. (0.064 cm) diameter guidewire positioned against the endocardial surface of potentially ischemic regions. Endocardial electrograms, left ventricular end-diastolic pressure and multiple surface ECG leads were recorded during rapid atrial pacing in 21 patients with coronary artery disease. Before pacing, endocardial electrograms in all 21 patients were free of ST elevation. Marked ST elevation was apparent in 17 of the 21 patients after rapid atrial pacing and could be abolished by nitroglycerin. Moreover, in several patients, endocardial ST elevation after rapid atrial pacing was abolished after successful percutaneous transluminal coronary angioplasty of the critically stenosed artery supplying the ischemic region of myocardium. It is concluded that ST elevation in the endocardial electrogram after rapid atrial pacing is a reflection of myocardial ischemia and may be a sensitive marker of pacing-induced ischemia appearing earlier than angina, postpacing increase in left ventricular end-diastolic pressure or ST depression in the surface ECG.     

Late failure of left ventricular leads stabilized using the retained guidewire technique in patients undergoing cardiac resynchronization therapy

The retained guidewire technique has been proposed as an alternative method for stabilizing the left ventricular lead in patients who experience repetitive intraoperative dislocation. This article concerns three patients, out of a total of 185 (1.6%) undergoing cardiac resynchronization therapy, who had to be treated using the retained guidewire technique because of demonstrable recurrent lead dislocation. Electrode parameters were all within normal limits. Although lead dislocation could not be demonstrated macroscopically, sensing and pacing parameters were found to have changed 6 months to 1 year after implantation, with a marked elevation in impedance. Laboratory analysis showed deformation and fracture of the coil electrodes as well as deterioration of the insulation coating. In conclusion, our experience shows that the retained guidewire technique should not be used because delayed electrode damage can occur.     

Permanent pacing of the bundle of His after radiofrequency atrioventricular node ablation in patients with suprahisian conduction disturbances]

INTRODUCTION AND OBJECTIVES: The asynchronic contraction of the left ventricle due to left bundle branch block or right ventricular pacing is inferior from a hemodynamic point of view to the synchronic contraction through the conduction system. Several authors have reported some cases of pump failure and deterioration of mitral regurgitation after AV nodal ablation. Alternative sites of pacing such as the right ventricular outflow tract pacing have been proposed in order to avoid these complications. Direct His bundle pacing might be a new alternative for permanent pacing, however, it has not been extensively evaluated in humans yet. Our aim is to prove the feasibility of permanent His pacing in terms of stability, thresholds and pump function. PATIENTS AND METHOD: Population: patients without structural heart disease, selected for AV nodal ablation due to uncontrolled paroxysmal atrial fibrillation, or for pacemaker implantation due to supraHis conduction disturbance, with normal conduction system. An active fixation permanent lead was placed in His position using an steering guidewire and a diagnostic catheter as an anatomical reference. We also implanted a lead in the right atrial appendage and both were connected to a DDDR generator. Pacing thresholds and ecocardiographic ventricular function parameters were evaluated (ejection fraction, cavity size, mitral regurgitation). RESULTS: 12 patients met the inclusion criteria. Successful His pacing was achieved in 8 out of 12 cases (66%) with acceptable thresholds at implantation (1.24 +/- 0.13 volts at 0.5 ms) and during follow up at 3 months (1.31 +/- 0.20 volts at 0.5 ms). Neither a significant change in the ecocardiographic parameters not a deterioration in the clinical status caused by ablation or stimulation was evidenced. CONCLUSION: The His bundle may be the site of choice for long term pacing in patients with AV block and normal infraHis conduction system.     

右心室心尖部不同起搏比率与左心室大小可能有关联

目的:探讨传统右室心尖部起搏与右室流出道间隔起搏对心功能的影响,以及右室心尖部不同起搏比例与左室大小的关系。方法:66例缓慢性心律失常患者行起搏治疗:46例为右室心尖部起搏,20例为中下位室间隔起搏,随访12个月,心脏超声评价术前、半年及1年的左房及左室内径、左室射血分数;对心尖部起搏组按心室起搏比率分为≥30%、<30%两组,同样心脏超声评价左房及左室内径、左室射血分数。结果:右心室心尖部组及右心室室间隔组,在手术前、手术后6个月及12个月其左心房内径、左心室舒张末内径及左室射血分数均无显著差别。心尖部起搏比率≥30%组与<30%组间左心房内径、左室射血分数未见显著区别,而左心室在半年及1年可见左心室舒张末径变化有显著差异,随着起搏比率增加,左心室舒张末内径增大。结论:右室起搏1年,起搏部位对左心结构及功能影响无统计学意义;右室心尖部高心室起搏比率(≥30%)可引起左心室舒张末内径的增大。     

Successful coronary pace-termination of ventricular tachycardia during coronary angioplasty

Coronary pacing has been performed to treat bradycardias occurring during percutaneous transluminal coronary angioplasty (PTCA) using an angioplasty guidewire. We describe a case of a 62-year-old man who developed ventricular tachycardia (VT) during PTCA. The tachycardia was successfully terminated by overdrive pacing via an angioplasty guidewire. Cathet. Cardiovasc. Diagn. 42:31–32, 1997. © 1997 Wiley-Liss, Inc.     

Left ventricular pacing through coronary sinus tributaries: initial experience.

BACKGROUND: Left ventricular pacing is increasingly being used as a part of biventricular pacing in congestive heart failure but data on safety, feasibility, reliability and lead maturation are sparse. METHODS AND RESULTS: Seventeen patients (13 males and 4 females) with persistent symptomatic degenerative complete heart block underwent temporary left ventricular pacing by a left subclavian puncture through the coronary sinus to its tributaries using a unipolar permanent pacing lead connected to an external pulse generator. The left ventricular pacing was done for two weeks. Permanent right ventricular apical pacing was also done at the same time through a right cephalic vein cut-down or subclavian puncture and the pacing rate was kept below that of the initial left ventricular pacing rate. Pacing parameters of the left and right ventricles were assessed at the time of implantation and at two weeks. Out of 17 patients, left ventricular pacing was successful in 11 (67.7%) patients. The time taken for the total procedure was 56+/-18.1 min. Lead displacement was noted in one patient without loss of pacing. At the time of implant and after two weeks, left ventricular pacing threshold, impedance, R wave height and slew rate were not different as compared to right ventricular pacing. Holter recording for 24 hours revealed regular left ventricular pacing at the end of two weeks in all patients. CONCLUSIONS: The present study shows that left ventricular pacing through coronary sinus tributaries is feasible and reliable. Acute and subacute maturation of left ventricular pacing are similar to right ventricular apical pacing.     

Effect of alteration of left ventricular activation sequence on the left ventricular end-systolic pressure-volume relation in closed-chest dogs

We investigated the effect of pacing from the atrium and various ventricular sites on the left ventricular end-systolic pressure-volume relation following autonomic blockade in a total of 10 dogs chronically instrumented to measure left ventricular pressure and determine left ventricular volume from three ultrasonic endocardial dimensions. During ventricular pacing, left ventricular end-diastolic volume, stroke volume, and end-systolic pressure were decreased, while the end-systolic volume was relatively unchanged. Left ventricular end-systolic pressure-volume relations were generated by vena caval occlusions during pacing at a constant rate from the left atria, and the epicardium of the right ventricular free wall, right ventricular apex, and left ventricular free wall. The left ventricular end-systolic pressure-volume relations were described by straight lines for each site (r greater than 0.96 and SEE less than 2.9 mm Hg in all but one instance). Compared to atrial pacing, the left ventricular end-systolic pressure-volume relations were shifted (P less than 0.001) to the right during pacing from ventricular sites. During atrial pacing, the volume intercept of the left ventricular end-systolic pressure-volume relation was 16.0 +/- 7.2 ml (mean +/- SD), and increased to 18.7 +/- 7.8 ml (P less than 0.05) during pacing from the right ventricular free wall, to 19.6 +/- 7.7 ml (P less than 0.05) during pacing from the right ventricular apex, and to 20.0 +/- 7.5 ml (P less than 0.05) during pacing from the left ventricular free wall. These volume intercepts correlated roughly with the extent of dyssynchronous activation as estimated by the QRS duration (r = 0.59 to 0.93) and the time for left ventricular endocardial activation (r = 0.92 and 0.95). During ventricular pacing, the slope of the left ventricular end-systolic pressure-volume relation changed only slightly. Similar results were obtained during pacing from right ventricular endocardial sites. We conclude that alterations of the normal activation sequence produced by ventricular pacing depress left ventricular pumping function independent of loading conditions, as indicated by a rightward shift of the left ventricular end-systolic pressure-volume relation. The extent of this shift appears to be in proportion to the degree of dyssynchronous activation. The decreased stroke volume during ventricular pacing is due both to a decreased end-diastolic volume (decreased preload) and the rightward shift of the end-systolic pressure-volume relation (decreased pump function).     

改良双弯曲指引导丝塑型法在右室流出道间隔部起搏电极定位中的应用

目的 探讨改良双弯曲指引导丝塑型法在右室流出道间隔部起搏电极定位中的应用价值。方法 选取72例行起搏器植入术患者,心室电极均定位于右室流出道间隔部,按电极指引导丝塑型法不同分为单弯曲指引导丝塑型法组（A组）、双弯曲指引导丝塑型法组（B组）、改良双弯曲塑型法组（C组）;三组采用相同右室流出道主动固定起搏电极植入方法,对比三组电极起搏参数、起搏电极固定操作参数、定位成功率、手术并发症以及术后3个月随访情况 。 结果 三组起搏阈值 、电极阻抗和R波振幅无明显差异（P〉0.05）,术后起搏时QRS波时限C组较B组短（P〈0.01）;C组较A、B两组X线曝光时间短、电极固定次数少（P〈0.05）,与A组比较,C组电极固定成功率高（P〈0.01）;术后随访3个月,C组无明显并发症发生。 结论 采用改良双弯曲指引导丝塑型法在右室流出道间隔部起搏电极定位中操作更简易,手术定位成功率高。     

A New Technique for the Transvenous Implantation of the Over-the-Wire Left Ventricular Pacing Lead in a Patient with Heart Failure

Implantation of left ventricular leads (LV) for biventricular pacing remains a technological challenge and failure of the procedure is not uncommon. We described a 58 year-old patient with heart failure and intraventricular conduction delay where difficulty is encountered when cannulating the coronary sinus by the guiding catheter. By placing a guiding catheter in the inferior portion of the right atrium, a coronary guidewire, preloaded with an over-the-wire lead system, was used to reach the lateral cardiac vein. This may help to reduce the implant failure rate and avoid other more invasive means of LV lead implantation.     

心室再同步化起搏的心电图表现及随访

目的探讨不同心室起搏部位体表十二导联心电图的变化及在双心室再同步起搏(CRT)随访中的应用。方法22例资料完整的充血性心力衰竭患者进行双心室再同步起搏治疗,其中21例经静脉置入左室导线,1例因冠状静脉窦畸形经胸左室外膜导线置入;右室导线均放置在心尖部。22例分别记录无起搏、右室起搏、左室起搏及双心室同步起搏四种不同状态下的十二导联心电图。结果22例术前心电图显示完全性左束支传导阻滞(CLBBB)16例,完全性心室内传导阻滞6例,行右室心尖部起搏时胸前导联(V1)均呈CLBBB型,肢体导联额面电轴左偏,Ⅰ导联呈r、R型占100%,左室起搏时胸前导联(V1)均呈右束支传导阻滞(CRBBB)型,额面电轴右偏,Ⅰ导联呈q、Q、QS型20例,占91%;双心室同步起搏后胸前导联(V1)呈CLBBB型13例,呈CRBBB型9例,额面电轴均右偏,Ⅰ导联呈q、Q、QS型占86.5%。结论不同部位心室起搏具有不同的心电图表现,双心室同步起搏具有特征性的心电图形态,CRT随访时通过对心电图形态和时限的观察有助于判断是否实现真正有效的双心室再同步起搏。     

Method and demonstration of direct confirmation of response to cardiac resynchronization therapy via preimplant temporary biventricular pacing and impedance cardiography

Temporary resynchronization therapy pacing is feasible, and impedance cardiography (ICG) can provide evidence of hemodynamic benefit before permanent pacemaker implantation. During an electrophysiologic study performed before permanent device implantation, a guidewire was placed in a tributary of the coronary sinus to allow pacing of the left ventricle. Temporary pacing was implemented in various modalities, during which time ICG was used to document the hemodynamic consequences of atrial pacing, dual-chamber pacing, and biventricular pacing, with biventricular pacing being hemodynamically most favorable.     

Cardiac resynchronization as therapy for congestive cardiac failure in children dependent on chronic cardiac pacing

Three patients with heart failure after chronic right ventricular apical pacing were treated with resynchronization. Biventricular pacing was used for two patients, and the other was treated with left univentricular pacing. In all patients, we observed a dramatic improvement of left ventricular dimension, function, and clinical state. We conclude that biventricular or left ventricular pacing is superior to right ventricular apical pacing in children who are pacemaker-dependent.     

Preload reduction with right ventricular pacing: Effects on left ventricular hemodynamics and contractile pattern

Studies were performed in 32 patients to evaluate left ventricular pressure-volume changes and contractile pattern during right ventricular pacing as compared to normal sinus rhythm. Coronary artery disease was present in 27 patients, while 5 patients (control group) had no evidence of coronary artery or left ventricular disease. Studies were performed during both normal sinus rhythm and right ventricular pacing at comparable heart rates, utilizing angiographic methods to determine heart volumes. Right ventricular pacing in all patients resulted in decreased left ventricular systolic (p< 0.01) and diastolic (p< 0.01) pressures and decreased stroke work (p< 0.001). In the control group, right ventricular pacing caused a decrease in left ventricular end-diastolic volume (p< 0.01) and stroke volume (p< 0.01), with no change in ejection fraction. The patients with coronary artery disease were divided into four groups, dependent on the left ventricular contractile pattern during normal sinus rhythm and the percentage of change in hemiaxis shortening during right ventricular pacing. In group A (six patients with asynergy) and group B (seven patients with asynergy), there was no significant change in the percentage of hemiaxis shortening during right ventricular pacing when compared to normal sinus rhythm. Ventricular volume studies in these patients (groups A and B) were similar to the control groups and no change in contractile pattern was observed during pacing. In group C, twelve patients had asynergy and a 10% increase in percentage of hemiaxis shortening during right ventricular pacing when compared to normal sinus rhythm. Right ventricular pacing resulted in decreased end-diastolic pressure (p< 0.01) and end-diastolic volume (p< 0.001), no change in stroke volume, and an increased ejection fraction (p< 0.01). Contractile patterns improved in all patients in group C during pacing. Group D consisted of two patients with asynergy and a 10% decrease in percentage of hemiaxis shortening during pacing, associated with a decrease in end-diastolic volume and ejection fraction with deterioration of left ventricular contractile pattern. These results indicate that right ventricular pacing in patients with coronary artery disease decreases preload, which may be accompanied by improved left ventricular contractile pattern (11/27) and in some patients (2/27) deterioration of left ventricular function.     

Alterations in left ventricular relaxation during atrioventricular pacing in humans

To determine whether the asynchronous left ventricular contraction-relaxation sequence that exists during right ventricular pacing alters left ventricular relaxation, measurements of both the maximal rate of decline of left ventricular pressure (peak negative dP/dt) and the time constant of left ventricular relaxation were obtained during atrial and atrioventricular (AV) pacing in 25 patients referred for diagnostic cardiac catheterization. Heart rate was maintained at 10 to 15 beats/min above the sinus rate at rest, and relaxation was assessed during atrial pacing, AV pacing and repeat atrial pacing. The patients were classified into two groups. Group 1 included 10 patients with normal left ventricular systolic function at rest (ejection fraction greater than 0.55) and without evidence of prior myocardial infarction. Group 2 included 15 patients with a depressed left ventricular ejection fraction or akinesia of one or more left ventricular segments on the contrast ventriculogram, or both. Heart rate, peak left ventricular systolic pressure, end-systolic pressure and end-diastolic pressure remained constant during atrial, AV pacing and repeat atrial pacing in all patients. In group 1 patients, the decrease in peak negative dP/dt (1,507 +/- 200 versus 1,424 +/- 187 mm Hg/s) and the increase in the time constant of left ventricular relaxation (48 +/- 11 versus 51 +/- 11 ms) during AV pacing was not significantly different when compared with values during atrial pacing.(ABSTRACT TRUNCATED AT 250 WORDS)