[Complex pacemaker dysfunction. Sometimes a problem does not come alone...]

The electrocardiogram of a multimorbid patient with a pacemaker is discussed. At first sight, it clearly shows dysfunction of an implanted pacemaker. However, this case illustrates that sometimes a second careful look is essential to reveal further hidden problems.

An unintentional left ventricular stimulation

A 31-year-old man had undergone pacemaker implantation for complete atrio-ventricular block six years before. Permanent ventricular stimulation was seen on the ECG. The QRS complex was negative in leads I, VL and V2 to V5. The ventricular lead tip was found to be screwed into a branch of the great cardiac vein. Unintentional coronary sinus fixed-screw lead implantation has not to our knowledge been reported before.

Initial experiences of maintaining atrioventricular intrinsic conduction during cardiac resynchronization therapy in non-responders

BACKGROUND

Cardiac resynchronization therapy (CRT) is a major breakthrough in therapy for advanced heart failure patients; however, a number of key clinical research questions remain, perhaps most importantly the issue of why apparently suitable patients do not respond to CRT.

METHODS

Seven patients, six males and one female, aged (56.43 +/- 6.13) years, all diagnosed with dilated cardiomyopathy, were included in this study. They were all non-responders to CRT who underwent routine optimization postoperatively, and received optimal drug therapy. On the basis of biventricular pacing, titrating various atrioventricular (AV) intervals were performed to get the true fusional QRS complexes composed of biventricular pacing and AV intrinsic conduction. Then, the effects of AV intrinsic conduction during CRT were evaluated.

RESULTS

On the setting of AV intrinsic conduction during CRT, the true fusional QRS complexes were the narrowest, and all patients showed alleviation of symptoms, improvement of exercise tolerance, life quality and hemodynamic parameters during more than 6 months of follow-up.

CONCLUSIONS

Titrating AV intervals to get the true fusional QRS complexes composed of biventricular pacing and AV intrinsic conduction will be beneficial for non-responders to CRT. Maintaining AV intrinsic conduction during CRT may decrease the rates of non-responders to CRT.

Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block

CONTEXT

Prolongation of the electrocardiographic PR interval, known as first-degree atrioventricular block when the PR interval exceeds 200 milliseconds, is frequently encountered in clinical practice.

OBJECTIVE

To determine the clinical significance of PR prolongation in ambulatory individuals.

DESIGN, SETTING, AND PARTICIPANTS

Prospective, community-based cohort including 7575 individuals from the Framingham Heart Study (mean age, 47 years; 54% women) who underwent routine 12-lead electrocardiography. The study cohort underwent prospective follow-up through 2007 from baseline examinations in 1968-1974. Multivariable-adjusted Cox proportional hazards models were used to examine the associations of PR interval with the incidence of arrhythmic events and death.

MAIN OUTCOME MEASURES

Incident atrial fibrillation (AF), pacemaker implantation, and all-cause mortality.

RESULTS

During follow-up, 481 participants developed AF, 124 required pacemaker implantation, and 1739 died. At the baseline examination, 124 individuals had PR intervals longer than 200 milliseconds. For those with PR intervals longer than 200 milliseconds compared with those with PR intervals of 200 milliseconds or shorter, incidence rates per 10 000 person-years were 140 (95% confidence interval [CI], 95-208) vs 36 (95% CI, 32-39) for AF, 59 (95% CI, 40-87) vs 6 (95% CI, 5-7) for pacemaker implantation, and 334 (95% CI, 260-428) vs 129 (95% CI, 123-135) for all-cause mortality. Corresponding absolute risk increases were 1.04% (AF), 0.53% (pacemaker implantation), and 2.05% (all-cause mortality) per year. In multivariable analyses, each 20-millisecond increment in PR was associated with an adjusted hazard ratio (HR) of 1.11 (95% CI, 1.02-1.22; P = .02) for AF, 1.22 (95% CI, 1.14-1.30; P < .001) for pacemaker implantation, and 1.08 (95% CI, 1.02-1.13; P = .005) for all-cause mortality. Individuals with first-degree atrioventricular block had a 2-fold adjusted risk of AF (HR, 2.06; 95% CI, 1.36-3.12; P < .001), 3-fold adjusted risk of pacemaker implantation (HR, 2.89; 95% CI, 1.83-4.57; P < .001), and 1.4-fold adjusted risk of all-cause mortality (HR, 1.44, 95% CI, 1.09-1.91; P = .01).

CONCLUSION

Prolongation of the PR interval is associated with increased risks of AF, pacemaker implantation, and all-cause mortality.

Severe obstructive sleep apnea syndrome with symptomatic daytime bradyarrhythmia

We report a case of severe obstructive sleep apnea (OSA) in a patient with symptomatic daytime cardiac bradyarrhythmia. Continuous positive airway pressure therapy prevented atrioventricular blocks that emerged after cardiac pacing for sick sinus syndrome. OSA could be associated with daytime bradyarrhythmia.

[Atrial sensing with fixed and floating electrodes at identical activities]

Despite advantages of single-lead VDD systems, the frequency of implantation of these pacemakers in patients with symptomatic atrioventricular block and normal sinus rhythm continues to decline. Therefore, data comparing the atrial sensing performance of floating and fixed electrodes at identical activities are rare. The aim of the study was to investigate atrial sensing via floating and fixed atrial electrodes at identical activity levels (supine position, left side position, seated position, hyperventilation, standing, walking, fast walking, walking up and down stairs, for 1.5 min each) by beat-to-beat analysis in 24 h Holter ECG. A total of 42 patients were included in the study (22 patients with a DDD system; 20 patients with a VDD system). In 45% of the DDD systems and only in 20% of the VDD systems an intermittent atrial undersensing during activity was recorded (p = 0.0024). The intermittent atrial undersensing in both groups was detected significantly more often in the first 15 s of an activity (p < 0.001). Floating sensing reduced the frequency of atrial undersensing in the initial phase of the activity significantly compared to atrial sensing by a fixed electrode (p = 0.0347). This advantage of floating electrodes and the significant earlier atrial signal recognition by floating electrodes might be useful in future DDD pacemakers by combining a VDD electrode with a fixed atrial electrode.

Contralateral pneumothorax after endocardial dual-chamber pacemaker implantation resulting from atrial lead perforation

We describe the occurrence of a right-sided pneumothorax following a left-sided dual chamber pacemaker implantation, due to a perforation of the screw of the J-shaped active-fixation lead through the right atrial wall. A review of the literature regarding complications of different atrial lead types (passive vs. active and J-shape vs. straight) is provided. Current data suggest that passive-fixation leads could have an advantage, provided they can be positioned satisfactorily because of the lower risk of pericardial complications. If active-fixation leads are used, straight leads might be preferable above J-shaped leads because of the lower rate of perforation.

Relationships between paced QRS duration and left cardiac structures and function

BACKGROUND

In patients with congestive heart failure, QRS duration (QRSd) is correlated with left ventricular (LV) ejection fraction (LVEF), ventricular dyssynchrony and patients' prognosis. However, little is known about the relationships between paced QRS duration (pQRSd) to cardiac structures and function and ventricular dyssynchrony in patients with chronic right ventricular apical (RVA) pacing, which were investigated in this study.

METHODS

Seventy patients implanted with DDD(R) pacemaker for high- or third-degree atrioventricular block were enrolled to study pQRSd and echocardiographic variables, including aortic root dimension (AO), left atrial dimension (LAD), LV end-systolic dimension (LVDs), LV end-diastolic dimension (LVDd), interventricular septum thickness (IVST), LV posterior wall thickness (LVPWT), LVEF, interventricular mechanical delay (IVMD), systolic asynchrony index (Ts-SD) and septal-to-lateral delay.The relationships between pQRSd and such variables were examined.

RESULTS

The pQRSd correlated positively with LVDd (r = 0.3166, P < 0.05), LVDs (r = 0.3741, P < 0.05), LAD (r = 0.5848, P < 0.01), IVST (r = 0.2925, P < 0.05), and negatively with LVEF (r = -0.3037, P < 0.05). No significant correlations were found between pQRSd and AO, LVPWT, IVMD, Ts-SD and septal-to-lateral delay (all P > 0.05). There was no significant correlation between LVEF and IVMD, Ts-SD, septal-to-lateral delay (P > 0.05). However, IVMD, Ts-SD and septal-to-lateral delay were greater in patients with low LVEF than in patients with normal LVEF (P < 0.05). A cut-off value for pQRSd of 180 ms had a sensitivity of 85.71% and a specificity of 66.67% to detect left atrial dilation.

CONCLUSION

pQRSd is correlated with left cardiac structures and LV systolic function. pQRSd > or =180 ms indicates left atrial dilation. There is no correlation between pQRSd and ventricular dyssynchrony.

[The floating structure connected with endocavitary electrode--thrombus or bacterial vegetation?]

A case of a 52-year-old woman with complete atrioventricular block, treated with pacemaker implantation, is presented. During the control transthoracic echo exam we observed floating structure connected with the endocavitary electrode. After diagnostic examinations bacterial vegetation was excluded and thrombus was diagnosed. The therapy with unfractionated heparin and warfarin was successfully performed.

Right ventricular apex pacing: is it obsolete?

Clinical trials in patients with pacemakers for sinus node dysfunction or atrioventricular block have highlighted the fact that desynchronization of ventricular contraction induced by right ventricular apical pacing is associated with long-term morbidity and mortality. These clinical data confirm pathophysiological results indicating that right ventricular apical pacing causes abnormal ventricular contraction, reduces pump function and leads to myocardial hypertrophy and ultrastructural abnormalities. In this manuscript, we discuss the clinical evidence for the adverse and beneficial effects of various right ventricular pacing sites, left ventricular pacing sites and biventricular pacing. We also propose a decisional algorithm for pacing modalities, based on atrioventricular conduction, left ventricular function and expected lifespan.

Changes in the mental and physical components of the quality of life for patients six months after pacemaker implantation

BACKGROUND

The additional purpose for pacemaker implantation, beyond treating arrhythmias and conduction disturbances, is to improve the quality of life (QoL) of the patient. Most previous research has shown this purpose to have been achieved. However, the question as to whether all mental and physical components improve QoL to the same degree is still valid. The purpose of this study is to evaluate changes in the primary mental and physical areas of QoL in patients six months after they have had a pacemaker implanted.

METHODS

Ninety eight patients with atrioventricular blocks (AVB) and 100 patients with sinus node dysfunction (SND) who were qualified for pacemaker implantation were included in this study. Every patient had a DDD(R)-type pacemaker with bipolar screw-in leads implanted. The ventricular lead was positioned in the right ventricular outflow tract. QoL was evaluated twice: three to five days before implantation and six months afterwards - the MLWHF questionnaire was used.

RESULTS

A very high statistical improvement in QoL (p approximately 0,0000) - reduced number of points was found in all five areas of QoL in patients with SND and in four areas in patients with AVB. In the 'anxiety/depression area' in patients with AVB, the average number of points was higher (p = 0.3871), so QoL was worse.

CONCLUSIONS

Implanting a pacemaker improves QoL in patients with AVB and SND. In patients with AVB, anxiety/depression is made more intense.

Prinzmetal's variant angina associated with severe heart rhythm disturbances and syncope: a therapeutic dilemma

Prinzmetal's angina is a distinct syndrome characterized by episodes of chest pain and transient ST-segment elevation caused by coronary vasospasm. This variant form of angina is sometimes associated with complete atrioventricular block and ventricular arrhythmias. We report here a case of variant angina with documented severe heart rhythm disturbances and syncope in a 66 year-old woman. Due to recurrent episodes of high-degree atrioventricular block, a DDD pacemaker was implanted. No further symptoms of angina or cardiac arrhythmias were detected on optimal therapy.

Reduction of atrioventricular valve regurgitation by atrioventricular sequential pacing for an adult with corrected transposition of the great arteries

The case of a 64-year-old woman who underwent corrected transposition of the great arteries with significant systemic atrioventricular valve regurgitation and complete atrioventricular block is described. The patient underwent implantation of a DDD-type pacemaker and experienced relief of symptoms after discharge. Follow-up evaluation 30 months after the pacemaker implantation demonstrated a decrease in the cardiothoracic ratio on chest X-ray, the b-type natriuretic peptide level, and regurgitation at the systemic atrioventricular valve.

Is the optimal atrioventricular delay paced from right ventricular outflow tract different from that from right ventricular apex?

The objective of this study was to compare the optimal atrioventricular delay (OAVD) paced from right ventricular outflow tract (RVOT) with that paced from right ventricular apex (RVA) in patients implanted with DDD pacemaker. A total of 43 patients implanted with DDD pacemaker due to high or third degree atrioventricular block were enrolled. The atrial lead was positioned in the right atrial appendage and the ventricular lead was randomly placed in RVOT (n=21) or RVA (n=22). AVD optimization increased aortic flow velocity integral both in RVOT and RVA paced patients. P wave duration (P<0.05) rather than QRS duration (P>0.10) was the independent determinant of OAVD. OAVD was similar between RVA and RVOT paced patients (116.81+/-34.00 ms vs 107.14+/-26.30 ms, P>0.05).

FDG-PET and MIBI-Tc SPECT as follow-up tools in a patient with cardiac sarcoidosis requiring a pacemaker

A 63-year-old man presented with recent-onset symptoms secondary to third-degree atrio-ventricular block, for which a dual-chamber pacemaker was inserted. Additional investigations resulted in the diagnosis of cardiac sarcoidosis. FDG-PET and MIBI-technetium SPECT were used as follow-up tools for monitoring active granulomatous myocardial infiltration.

Cardiac pacing in hypertrophic cardiomyopathy: a cohort with 24 years of follow-up

BACKGROUND

The benefits of heart stimulation in hypertrophic cardiomyopathy (HCM) patients have been questioned. Research work available in Brazil on those benefits is scarce.

OBJECTIVE

To describe the indication, clinical response, complications and survival time related to pacemaker implant in HCM patients.

METHODS

Thirty-nine hypertrophic cardiomyopathy patients were studied (41% males) and submitted to pacemaker implant from May, 1980 through November, 2003.

RESULTS

Twenty-seven patients presented obstructive hypertrophic cardiomyopathy, and 12, non-obstructive. Mean age was 46.4 years of age (range 14-77), with follow-up of 6.4+/-4.1 years. Major indications for implant were: spontaneous or induced atrioventricular block (54%), refractoriness to therapeutic conduct associated to high gradient (33%), support for drug therapy to treat bradychardia (8%), and atrial fibrillation prevention (5%). Functional class was shown to improve from 2.41+/-0.87 to 1.97+/-0.92 (p=0.008), and symptoms referred were reduced. No change was made in drug therapy administration. No procedure-related deaths were reported. Although shown to be safe, the procedure was not free from complications (6 patients--15.4%). Three deaths occurred in the follow-up period--the three of them were atrial fibrillation female patients, with evidence of functional deterioration. A close association was observed between clinical condition worsening and the onset of atrial fibrillation or flutter.

CONCLUSION

Cardiac pacing in HCM patients was successful, with evidence of symptoms relief in obstructive HCM patients. No functional improvement was observed in non-obstructive patients.

Efficiency, reproducibility and agreement of five different hemodynamic measures for optimization of cardiac resynchronization therapy

BACKGROUND

Several hemodynamic measures have been used for optimization of the AV delay of cardiac resynchronization therapy (CRT), including pulse pressure (PP), systolic blood pressure (SBP) and cardiac output (CO). We aimed to determine whether these measures identify the same optimum and whether they have the same efficiency and reproducibility at identifying this optimum.

METHODS AND RESULTS

In 22 patients with cardiac resynchronization therapy, we adjusted the AV delay while atrially pacing at 110 bpm and simultaneously recording SBP, diastolic blood pressure (DBP), PP, mean arterial pressure (MAP) and CO. SBP, PP and CO all had essentially the same signal-to-noise ratios (15.4+/-5.4, 15.5+/-6.4, 15.3+/-7.4 respectively p=NS). In contrast, MAP and DBP had significantly worse signal-to-noise ratios than SBP (14.2+/-5.6, p=0.003 and 12.1+/-4.4, p<0.0001 respectively). The optimal AV delay was very similar between SBP, PP, MAP and DBP. For example, the optima identified by SBP correlated strongly with those identified by PP (r=0.94), MAP (r=0.96) and DBP (r=0.90). In contrast, the optima detected by CO was poorly related to these (e.g. r=0.36 with SBP optima). Reproducibility was best for optima detected by SBP followed by MAP and PP.

CONCLUSIONS

Essentially the same AV optimum is identified, regardless of whether the parameter chosen for maximization is SBP, PP, MAP or DBP. We conclude that optimizing the CRT AV delay using SBP gives the best combination of efficiency and reproducibility, with PP and MAP being reasonable alternatives.

Right ventricular outflow tract pacing: relation of high to low synchronous ventricular activation with cardiac memory

Cardiac memory is usually observed after right ventricular apical pacing and considered to be related to alter asynchronous activation by apical pacing. However, it is not known whether it occurs by unaltered high to low synchronous ventricular activation by right ventricular outflow tract (RVOT) pacing. We present here a case with dual chamber pacemaker whose ventricular lead positioned in the RVOT and developed cardiac memory immediately after ventricular pacing had stopped and the underlying sinus rhythm resumed.

[Complete atrioventricular block in a patient with rheumatoid arthritis]

Atrioventricular (AV) block is rare in patients with rheumatoid arthritis (RA), but it is usually of complete type. A 55-year-old woman had complaints of fatigue, dizziness, and light-headedness, all of a week history. She had been receiving treatment for RA for about six years, and had been on methylprednisolone 5 mg/day for a year. On physical examination, her heart rate was 32 bpm, blood pressure was 160/80 mmHg. She had a grade 1-2/6 apical systolic ejection murmur. The electrocardiogram showed complete AV block. Transthoracic echocardiography showed grade I mitral regurgitation. No rheumatoid nodule was noted on transesophageal echocardiography. Coronary arteries appeared normal on coronary angiography. A temporary pacemaker was implanted in the coronary care unit, after which complete AV block improved to a second-degree Mobitz type II block. Her heart rate was 45 bpm. As no further improvement was observed in the AV block during a 10-day monitoring, she underwent DDD-R permanent pacemaker implantation.

[Extremely elderly patient in whom the pacing lead was implanted via the femoral vein]

We report on an extremely elderly patient in whom we were unable to insert a pacing lead via the subclavian or internal jugular vein because of a superior vena cava obstruction; we instead inserted the pacing lead via the femoral vein. The patient was a 98-year-old male. Thirty-nine years previously, pacemaker implantation was performed for complete atrioventricular block. Afterwards, pacemaker replacement and reimplantation had been performed a total of 15 times. The patient was recently admitted because of pacing failure. Pacemaker replacement was performed, but pacing was not possible because of disconnection of the pacing lead. Insertion of a new pacing lead was attempted via both subclavian veins and the right jugular vein but failed; this approach was abandoned and temporary pacing was done. Superior vena cava obstruction was noted on chest computed tomography (CT), and pacing lead insertion through the superior vena cava was deemed unfeasible. Myocardial electrode implantation was also considered, but general anesthesia was deemed problematic because of the patient's extreme age. A pacing lead was inserted via the right femoral vein, and the generator was implanted in the right lower abdomen. Postoperative pacing was satisfactory.

[Avoidance of ventricular pacing in patients with sinus node disease or intermittent AV block]

In patients with frequent right ventricular stimulation, worsening of heart failure and atrial fibrillation may occur. Avoidance of unnecessary right ventricular pacing is a major requirement for pacemaker selection and programming in patients with sinus node disease or intermittent AV block. In dual chamber pacemakers this goal can be achieved by programming a long AV delay or an AV delay hysteresis. Algorithms that allow AAI pacing in a dual chamber pacing mode and change to DDD mode in case of high degree AV block are a new attempt to avoid unnecessary right ventricular pacing. The article describes various strategies to avoid unnecessary ventricular pacing and discusses their advantages and disadvantages.

Myocardial scintigraphy after pacemaker implantation for congenital complete atrioventricular block

Patients with isolated congenital complete atrioventricular block (CCAVB) occasionally develop dilated cardiomyopathy (DCM), despite early pacemaker implantation. However, the etiology of the DCM and its relationship to permanent ventricular pacing are not fully understood. Twenty-five patients with CCAVB underwent (99m) technetium (Tc) myocardial perfusion scintigraphy. Five patients were studied before and after pacing, providing a total of 30 image sets, which were divided into three groups; group 1: CCAVB before pacemaker implantation (PMI) (n = 11); group 2: CCAVB after PMI who did not subsequently develop DCM (n = 13); group 3: CCAVB after PMI who subsequently developed DCM (n = 6). Perfusion defects on single-photon-emission computed tomography (SPECT) were identified in group 1, 0 of 11 patients; group 2, 85% of patients; and group 3, 100% of patients. In groups 2 and 3, in patients with right ventricular pacing, the perfusion defects were mainly in the septum or between the apex and septum. On 20 segments' polar maps, the distribution of %uptake showed a similar pattern in groups 2 and 3, the degree of decreased %uptake and the number of segments with decreased %uptake being more severe in group 3. "Artificial" left bundle branch block (LBBB) pattern myocardial contraction induced by right ventricular pacing decreased myocardial perfusion around the apex and septum. Some patients with CCAVB will develop left ventricular dysfunction caused by artificial LBBB-induced interventricular asynchrony.

[Prognosis of isolated atrioventricular block in children. Single center study of 135 cases]

INTRODUCTION

Isolated complete atrio-ventricular (AV) block in children occurs in anatomically normal hearts in the absence of any known predisposing factor likely to have caused the block. This study aimed to define the current prognosis of these conduction disorders.

METHODS

135 patients with isolated complete AV block, diagnosed before the age of 15 years, were included in this monocentric, retrospective study.

RESULTS

52.6% of the cases were diagnosed in the antenatal or neonatal period, demonstrating their congenital nature. The disease was heralded by symptoms in only 6.7% of cases. A search for maternal anti-Ro/La antibodies was performed in 111 of the patients. It was positive in 56 cases, and was associated with an early diagnosis, a short delay in cardiac pacemaker implantation, and the occurrence of cardiomyopathy (16 cases), the latter representing a critical point in the progression of the disease (37.5% mortality at 6 years). Among the 55 cases not associated with antibodies, 2 cases were familial and no etiology was discovered in the others. The diagnosis was therefore made later, and no progression to cardiomyopathy was noted. A cardiac pacemaker was implanted in 122 patients (66 epicardial, 56 endocardial).

CONCLUSIONS

Isolated complete AV block in children is not a homogenous entity: 'immunological' blocks are genuinely congenital and their prognosis remains grave, owing to the risk of cardiomyopathy, which is sometimes diagnosed late. The other types of block are diagnosed much later in childhood, and their mechanism is still unknown. They have a good prognosis as long as the indications for pacing the child are respected.

[Right ventricular perforation by screw-in lead after permanent pacemaker implantation: a case report]

A 93-year-old man received a permanent implanted pacemaker(VVI mode) to treat completed atrioventricular block in our hospital. However, pacing failure appeared 4 days later. Computed tomography showed right ventricular perforation by the screw-in lead. There was no evidence of cardiac tamponade or symptoms, so we inserted another lead into the right ventricular outflow tract without removing the first lead. This patient still has the pacing lead that perforated the right ventricle, so careful observation will be needed even after discharge.

Swallow syncope associated with complete atrioventricular block in an adolescent

We describe a 16-year-old female with a history of swallowing-induced syncope. The physical examination, ECG, echocardiography, barium swallow test, and thyroid function tests were within normal limits. The ambulatory ECG revealed intermittent complete atrioventricular block only associated with swallowing. There was also intermittent first-degree atrioventricular block not related to eating. An electrophysiologic study was performed during the implantation of a single-chamber transvenous ventricular pacemaker. There was mild atrioventricular nodal conduction disturbance with a His-ventricular interval of 70 msec and Wenckebach cycle length of 420 msec. During 1 year follow-up, the patient remained asymptomatic.

Computer model for the optimization of AV and VV delay in cardiac resynchronization therapy

An optimal electrode position, atrio-ventricular (AV) and interventricular (VV) delay in cardiac resynchronization therapy (CRT) improves its success. An optimization strategy does not yet exist. A computer model of the Visible Man and a patient heart was used to simulate an atrio-ventricular and a left bundle branch block with 0%, 20% and 40% reduction in interventricular conduction velocity, respectively. The minimum error between physiological excitation and pathology/therapy was automatically computed for 12 different electrode positions. AV and VV delay timing was adjusted accordingly. The results show the importance of individually adjusting the electrode position as well as the timing delays to the patient's anatomy and pathology, which is in accordance with current clinical studies. The presented methods and strategy offer the opportunity to carry out non-invasive, automatic optimization of CRT preoperatively. The model is subject to validation in future clinical studies.

Acute and chronic effects of cardiac resynchronization in patients developing heart failure with long-term pacemaker therapy for acquired complete atrioventricular block

AIMS

We assessed the effects of cardiac re-synchronization therapy (CRT) in patients who developed otherwise unexplained heart failure (HF) during right ventricular apical (RVA)-pacing for acquired complete atrioventricular block (CAVB).

METHODS AND RESULTS

Eighteen consecutive CAVB patients with HF during RVA-pacing were assessed with haemodynamic studies immediately and 12 months after CRT-upgrade. Ten patients had idiopathic CAVB and 13 showed normal left ventricular (LV) function at RVA-pacemaker implantation. HF developed after 81 +/- 10 months. RVA-pacing duration correlated (r = 0.49, P < 0.05) with LV ejection fraction (LVEF) deterioration. Biventricular- (BiV) and LV-pacing acutely improved the systolic function comparably, but only BiV improved diastolic function. One-year post-CRT-initiation, New York Heart Association classification improved 35 +/- 3% (P < 0.05) and the number of hospitalizations decreased 85 +/- 3% (P < 0.0001). CRT decreased LV end-diastolic diameter (LVEDd) 7 +/- 2% (P < 0.01) and increased LVEF by 23 +/- 7% (P < 0.01). The CRT-induced reduction in LVEDd tended to be greater in patients with RVA-pacing for < 5 years vs. > 5 years (7.7 +/- 2.5 vs. 3.6 +/- 1.0 mm, P = 0.08).

CONCLUSION

CRT-upgrade improves the cardiac function and symptoms in CAVB patients with HF progression related to RVA-pacing. Because adverse LV-remodelling may be partly irreversible, consideration should be given to BiV- and LV-pacing upgrade as soon as possible after the indications appear, and prospective studies of the optimal timing of CRT-upgrade may be useful.

Long-Term Effects of Atrial Synchronous Ventricular Pacing on Systolic and Diastolic Ventricular Function in Patients with Normal Left Ventricular Ejection Fraction

BACKGROUND

Atrial synchronous right ventricular pacing (VP) may compromise ventricular function in patients undergoing pacemaker implantation for atrioventricular block. We assessed the usefulness of tissue Doppler imaging (TDI) and color M-mode echocardiography in evaluating patients with VP, and examined the long-term effects of VP on ventricular function by echocardiographic indices and B-type natriuretic peptide (BNP) measurements.

METHODS

We studied 60 clinically stable elderly dual-chamber pacemaker recipients (mean age: 74 +/- 9 years) who had normal left ventricular (LV) systolic function and on the long term the same cardiac rhythm, either intrinsic normal ventricular activation (IA) (n = 20), or VP (n = 40).

RESULTS

Paced patients, compared to patients with IA, had decreased stroke volume (p < 0.05) and a more depressed relaxation pattern, as indicated by decreased peak early mitral velocity (E)/peak atrial contraction velocity ratio and tissue Doppler imaging (TDI)-early transmitral diastolic velocity (Ea) measures (p < 0.05). Both groups presented similar BNP levels and LV filling pressures, as assessed by E/Ea and E/early diastolic transmitral flow propagation velocity. In VP patients, age (beta = 0.31), Ea (beta = -0.28) and E/Ea (beta = 0.32) emerged as independent predictors of BNP levels.

CONCLUSIONS

VP is associated with reduced LV systolic function and signs of impaired relaxation. Elevated BNP levels in elderly VP patients with normal ejection fraction may be predicted by TDI signs of LV diastolic dysfunction.

AAIsafeR Limits Ventricular Pacing in Unselected Patients

INTRODUCTION

Dedicated pacing modes, such as AAIsafeR, prevent ventricular (V) pacing in selected patients. We report our experience in consecutive unselected patients.

METHODS

All data collected in recipients of Symphony DR 2550 pacemakers (ELA Medical, Montrouge, France) were retrospectively analyzed. At each visit, the percentage of V and atrial (A) pacing and the number of endless-loop tachycardia (ELT) episodes detected by the device were retrieved. Data were pooled according to pacing mode and compared with non-paired Student's t-test. Between April 2004 and July 2005, our center recruited 147 patients (mean age = 80 +/- 9 years, 54% men) treated for AV block (n = 58), sinus node dysfunction (n = 48) or other indications (n = 41). Mean age at implant was 80 +/- 9 years, and 54% were men. AAIsafeR(R) was programmed in 96 patients, DDD(R) in 43, DDI in 7, and DDD/AMC in 1 patient. In DDD mode, the mean resting AV delay was set at 150 +/- 17 ms. Patients were seen 1 month after implantation of the pacing system to verify its proper function, and every 6 months thereafter. At each follow-up, the percentage of ventricular and atrial pacing, and the number of ELT detected by the device, were recorded.

RESULTS

The mean follow-up was 7 +/- 6 months (range 1-21). No device was reprogrammed from AAIsafeR(R) to DDDI(R) because of permanent AF. Only 6 devices (6.25%) were automatically reprogrammed from AAIsafeR(R) to DDD(R) during follow-up due to permanent AV block. An empirical choice of AAIsafeR pacing mode at the time of implantation was effective in 94% of patients, allowing a significant decrease in the percentage of V pacing. AAIsafeR versions 1 or 2 significantly decreased the percentage of V pacing (9 +/- 21%) compared with DDD (95 +/- 14%), DDD/AMC (31 +/- 34%), and DDI (87 +/- 20%) pacing (P < 0.00001). The mean percentage of V pacing was 12 +/- 24% (median 0%, range 0-94) in AAIsafeR1 versus 4 +/- 12% (median 0%, range 0-52) in AAIsafeR2 (P = .055). In 16 devices upgraded from AAIsafeR version 1 to version 2, with follow-up analyzable in both modes, the mean percentage of V pacing decreased from 6.4 +/- 15.1% to 2.6 +/- 9.7% (ns). No adverse effect related to the AAIsafeR modes was observed. No patient reported palpitation, dyspnea, or lightheadedness attributable to overdrive pacing by the AF prevention algorithms, and there was no rehospitalization, need for cardioversion, device-related complication, or death.

CONCLUSIONS

In unselected pacemaker recipients, AAIsafeR reliably prevented V pacing compared with other pacing modes. No adverse effects were reported by any patient. Furthermore, maintaining spontaneous AV conduction protected the patients against ELT episodes.

Randomized Comparison of Bipolar vs Unipolar Plus Bipolar Recordings During Atrioventricular Junction Ablation Importance and Efficacy of Unipolar Recording

BACKGROUND

No prior studies have clarified the utility and efficacy of unipolar recording for identifying successful sites for atrioventricular junction (AVJ) ablation.

METHODS AND RESULTS

Thirty-six patients underwent radiofrequency (RF) AVJ ablation for drug-resistant atrial fibrillation (AF) or AF/flutter. AVJ ablation was performed with either bipolar (Bi-group; n=18) or unipolar plus bipolar recording (Uni-group; n=18). In the Uni-group, the primary parameter used to select ablation sites was a QS or rS morphology of the His bundle unipolar recording. There was no significant difference between the 2 groups for the bipolar electrogram characteristics at the successful ablation site. However, in the Uni-group, the procedure time and fluoroscopy duration were shorter (both p<0.05), and the total number of RF energy applications less (p<0.05) than in the Bi-group. In the Uni-group, unipolar His bundle recordings could be assessed in 26 (76%) of 34 RF energy applications: Complete atrioventricular block was obtained at 15 (83%) of 18 sites with QS morphology and in 3 (37%) of 8 sites with rS morphology on the unipolar His bundle recording.

CONCLUSIONS

AVJ ablation can be achieved more efficiently and with fewer RF energy applications when guided by unipolar recordings than by bipolar recordings alone.

[Aortal regurgitation and atrioventricular block III in Wegener's granulomatosis]

The article presents a clinical observation of a female patient suffering from Wegener's granulomatosis with a rare variant of cardiac involvement--a combination of an aortal valvular disease (aortal regurgitation) and total atrioventricular blockade--who later underwent pacemaker implantation. The direct cause of the lethal outcome in this patient was destructive pancreatitis. Data from Russian and foreign literature on cardiac pathology in patients with Wegener's granulomatosis are analyzed.