Conservative Treatment of Chronic Heart Block

A study of 203 patients with chronic heart block treated with oral long-acting isoprenaline showed that 85 (42%) were maintained satisfactorily on the drug for a mean period of 18.2 months. The survival rates at one, two, and three years were 76%, 64%, and 57% respectively. In 115 patients treatment by pacing became necessary to control symptoms, and in these patients the survival rates at one, two and three years were 83%, 72%, and 60%.The two most valuable guides to patients'' response to oral isoprenaline are the response to a trial dose of intravenous isoprenaline and the type of dysrhythmia associated with their Adams-Stokes attacks. Patients with heart failure with slow ventricular rates and those with angina of effort do not respond to treatment with sympathomimetic drugs.The majority of patients with chronic heart block are elderly, and in view of the complexity of pacing systems, and the need for skilled supervision of paced patients, oral long-acting isoprenaline remains of value in the longterm management of chronic heart block, provided patients are carefully selected for this form of therapy.     

Ventricular asystole due to inhibition of ventricular backup pacing by a dual chamber pacemaker: possible pitfalls of default settings

A 62-year-old patient presented with dizzy spells after her dual chamber pacemaker (Medtronic Enrhythm P1501DR), implanted for complete AV block, had been reprogrammed to deliver antitachycardia therapy (ATP) for paroxysmal atrial tachycardia. Her symptoms were caused by inhibition of ventricular backup pacing during ATP, leading to ventricular asystoles. Inhibition was the result of premature ventricular beats occurring prior to ATP: when ventricular backup pacing is left in the default setting, this pacemaker withholds backup pacing if any of the four preceding events is a sensed event. This case illustrates the possibly hazardous effects of default pacemaker settings, especially in pacemaker-dependent patients. (Neth Heart J 2010;18:323-6.)     

Usefulness Of Ivabradine To Treat "unexpected" Heart Failure Caused By "acute" Right Ventricular Pacing

We present the case of a patient with a heart failure episode induced by acute right ventricular pacing. After reversal of beta-blockers because of chronic obstructive pulmonary disease (COPD) exacerbation, the following sinus tachycardia caused a 2:1 atrioventricular block and consequent continuous right ventricular pacing. He was treated with the selective I(f) inhibitor ivabradine, that reduced both ventricular pacing percentage and heart rate without affecting atrioventricular conduction. Ivabradine may be a valuable option in treatment of patients with atrioventricular conduction disturbances.     

A Novel pacing option in patients with endomyocardial fibrosis: A case series

Endomyocardial fibrosis (EMF) is characterized by fibrous tissue deposition on the endocardial surface leading to impaired filling of one or both ventricles, resulting in either right or left heart failure or both. Although Sinus node dysfunction and tachyarrhythmia - atrial fibrillation, ventricular tachycardia, have been commonly reported, complete heart block (CHB) necessitating a pacemaker is rare in EMF. Transvenous pacing is technically limited by fibrotic obliteration of the affected ventricle that results in poor lead parameters, and alternative pacing strategy like epicardial pacing may be required in many. We report three cases of EMF, who were treated with an alternative pacing strategy.     

An Approach to the Stepwise Management of Severe Mitral Regurgitation with Optimal Cardiac Pacemaker Function

Right ventricular apical pacing may cause or worsen mitral regurgitation (MR). Potential mechanisms for this adverse sequelae include intraventricular dyssynchrony, altered papillary muscle function, pacing-induced cardiomyopathy with left ventricular dilation, and annular dilation. In contrast, biventricular (BiV) pacing may improve MR presumably by opposing the negative effects. Whether or not left ventricular lead location is important in treating mitral regurgitation in patients with pacemakers is unknown.We report a case of severe MR and left ventricular (LV) systolic failure in a patient with right ventricular pacing. Multiple potential etiologies for the worsening valve function were noted, and a stepwise iterative optimizing scheme that included basal lateral LV pacing improved mitral valve function and ameliorated heart failure symptoms.     

A simplified study of trans-mitral Doppler patterns

Background

Electrical fusion between left ventricular pacing and spontaneous right ventricular activation is considered the key to resynchronisation in sinus rhythm patients treated with single-site left ventricular pacing.

Aim

Use of QRS morphology to optimize device programming in patients with heart failure (HF), sinus rhythm (SR), left bundle branch block (LBBB), treated with single-site left ventricular pacing.

Methods and Results

We defined the "fusion band" (FB) as the range of AV intervals within which surface ECG showed an intermediate morphology between the native LBBB and the fully paced right bundle branch block patterns. Twenty-four patients were enrolled. Echo-derived parameters were collected in the FB and compared with the basal LBBB condition. Velocity time integral and ejection time did not improve significantly. Diastolic filling time, ejection fraction and myocardial performance index showed a statistically significant improvement in the FB. Interventricular delay and mitral regurgitation progressively and significantly decreased as AV delay shortened in the FB. The tissue Doppler asynchrony index (Ts-SD-12-ejection) showed a non significant decreasing trend in the FB. The indications provided by the tested parameters were mostly concordant in that part of the FB corresponding to the shortest AV intervals.

Conclusion

Using ECG criteria based on the FB may constitute an attractive option for a safe, simple and rapid optimization of resynchronization therapy in patients with HF, SR and LBBB.     

New concepts in pacemaker syndrome

After implantation of a permanent pacemaker, patients may experience severe symptoms of dyspnea, palpitations, malaise, and syncope resulting from pacemaker syndrome. Although pacemaker syndrome is most often ascribed to the loss of atrioventricular (A-V) synchrony, more recent data may also implicate left ventricular dysynchrony caused by right ventricular pacing. Previous studies have not shown reductions in mortality or stroke with rate-modulated dual-chamber (DDDR) pacing as compared to ventricular-based (VVI) pacing. The benefits in A-V sequential pacing with the DDDR mode are likely mitigated by the interventricular (V-V) dysynchrony imposed by the high percentage of ventricular pacing commonly seen in the DDDR mode. Programming DDDR pacemakers to encourage intrinsic A-V conduction and reduce right ventricular pacing will likely decrease heart failure and pacemaker syndrome. Studies are currently ongoing to address these questions.     

Non-pharmacological treatment of atrial fibrillation

In selected patients with atrial fibrillation and severe symptoms, non-pharmacological treatment may be an alternative or supplement to drug therapy. Atrioventricular nodal radiofrequency ablation (requires pacemaker implantation), or atrial pacing for sick sinus syndrome, are established treatment modalities. All other non-pharmacological therapies for atrial fibrillation are still experimental. After the Maze operation, atrial depolarization has to follow one specific path determined by surgical scars in the myocardium. This prevents new episodes of atrial fibrillation, but at a cost of perioperative morbidity and mortality. Catheter-based "Maze-like" radiofrequency ablation is technically difficult, and thrombo-embolic complications may occur. Paroxysmal atrial fibrillation sometimes is initiated by spontaneous depolarizations in a pulmonary vein inlet. Radio frequency ablation against such focal activity has been reported with high therapeutic success, but the results await confirmation from several centres. For ventricular rate control, most electrophysiologists presently prefer ablation to induce a complete atrioventricular conduction block (with pacemaker) rather than trying to modify conduction by incomplete block. Atrial or dual chamber pacing may prevent atrial fibrillation induced by bradycardia. It remains to confirm that biatrial or multisite right atrial pacing prevents atrial fibrillation more efficiently than ordinary right atrial pacing. An atrial defibrillator is able to diagnose and convert atrial fibrillation. The equipment is expensive, and therapy without sedation may be unpleasant beyond tolerability.     

Can Right Ventricular Pacing be Useful in the Assessment of Cavo-tricuspid Isthumus Block?

Background

Cavo-tricuspid isthmus (CTI) block is currently assessed by coronary sinus (CS) pacing or low lateral and septal atrial pacing. Occasionally, CS catheterization through the femoral route can be difficult to perform or right atrial pacing can be problematic because of catheter instability or saturation of the atrial electrograms recorded near the catheter.

Objectives

Our aim was to evaluate the feasibility of assessing cavo-tricuspid isthmus block by means of right ventricular (RV) pacing in patients with ventriculo-atrial conduction, comparing it with CS pacing.

Methods

Circumannular activation was analyzed during CS and RV pacing in consecutive patients in sinus rhythm undergoing CTI ablation for typical atrial flutter. Patients without ventriculo-atrial conduction were excluded from the study. The linear lesion was created during RV pacing and split atrial signals on the ablation line were analyzed. CTI block was confirmed by analyzing local electrograms on the line of block and circumannular activation during CS and RV pacing.

Results

Out of 31 patients, 20 displayed ventriculo-atrial conduction (64%) and were included in the study. Before ablation, during RV stimulation, the collision front of circumannular activation shifted counterclockwise in contrast with the pattern observed during CS pacing. After ablation, circumannular activation was similar during CS and RV pacing, showing fully descending lateral right atrium activation, even if double potentials registered on the ablation line were less widely split during RV pacing than CS pacing (111±26 ms vs 128±30 , p=0.0001).

Conclusions

In patients with ventriculo-atrial conduction, tricuspid annulus activation during CS and RV pacing is similar, before and after CTI ablation. The occurrence of split atrial electrograms separated by an isoelectric interval registered on the line of block can be detected during CS or RV pacing. In patients with difficult CS catheterization via the femoral vein, before trying the subclavian or internal jugular route, if retrograde ventriculo-atrial conduction is present, RV pacing can be an easy trick to assess isthmus block.     

Permanent parahisian pacing

Right Ventricular Apical permanent pacing could have negative hemodynamic effects. A physiologic pacing modality should preserve a correct atrio-ventricular and interventricular synchronization. This can be obtained through biventricular pacing, left ventricular pacing, or from alternative right ventricular pacing sites. Direct His Bundle Pacing (DHBP) was documented as reliable and effective for preventing the desynchronization and negative effects of right ventricular apical pacing. It is, however, a complex method that requires longer average implant times, cannot be carried out on all patients and presents high pacing thresholds. On the contrary, the parahisian pacing, with simpler feasibility and reliability criteria, seems to guarantee an early invasion of the His-Purkinje conduction system, with a physiological ventricular activation, very similar to the one that can be obtained with direct His bundle pacing. We present our experience on 68 patients who underwent a permanent right ventricular pacing in hisian/parahisian region, for advanced AV block and narrow QRS. In the first 17 patients we performed a double-blind randomized controlled study, with two 6-months cross-over periods in parahisian and apical pacing, documenting a significant improvement of NYHA class, exercise tolerance, quality of life score, mitral and tricuspidal regurgitation degree, and interventricular mechanical delay. In the subsequent 51 patients, in a mean follow of 21 months/patient, the pacing threshold remained stable (0.7+/-0.5 V implant; 0.9+/-0.7 V follow-up; p=0.08). The ejection fraction maintained medium-long term stable values, confirming the fact that the parahisian pacing can prevent deterioration of the left ventricular function. Parahisian pacing, therefore, has proven to be a reliable method, easy to apply and effective in preventing the negative effects induced by non-physiological right ventricular apical pacing.     

Myocardial Infarction and Complete Heart Block

The clinical and electrocardiographic records of 20 patients with complete A-V block due to acute myocardial infarction have been analyzed. This study indicated that patients with an inferior wall myocardial infarction had, most commonly, a block above the bifurcation. The block was transitory, the patients had no Stokes-Adams attacks and the outcome was good. None of our patients required artificial pacing. On the other hand, patients with an anteroseptal myocardial infarction suffered from a bilateral bundle branch block (below the bifurcation). They had severe Stokes-Adams attacks and they all required artificial pacing. The destruction of the conducting system was extensive and the outcome was poor. Five out of seven patients treated with artificial pacing recovered the A-V conduction through the left bundle within a few days. However, in spite of this they all died.From this small series clearly defined clinical and electrocardiographic features can be identified in two different groups of cases.     

Normalisation of the ECG in a patient with right bundle branch block by cardiac pacing

Right ventricular apical pacing (RVA) appears to have potential deleterious effects on myocardial systolic and diastolic left ventricular function, especially in patients with intact AV conduction. Therefore, new pacing sites in the right ventricle are being explored to overcome these detrimental effects. Alternative pacing sites in the right ventricle are the right ventricular outflow tract (RVOT) and the right ventricular septum (RVS). In this case report, we demonstrate an exceptional form of ventricular fusion, namely normalisation of the QRS complex in a patient with pre-existing right bundle branch block by RVS pacing. To our knowledge, this is the first report in the literature where right ventricular pacing could restore a complete RBBB to a normal QRS complex by stimulating distally from the anatomical position of the RBBB, due to fusion between artificial right ventricular stimulation and intrinsic conduction over the left bundle of the specific His-Purkinje system.     

Venous Graft Surgery in Treatment of Coronary Heart Disease

Sixty-seven patients have had aortocoronary venous graft bypass surgery by one surgeon for the relief of symptoms of severe coronary heart disease, including eight emergency operations. The overall operative, hospital, and late mortality was low in patients with favourable myocardial function and no previous myocardial infarction. There was a 7% mortality in patients with a normal preoperative chest radiogram, 8% mortality when the left ventricular end-diastolic pressure was normal preoperatively, and a 5% mortality in patients who had normal left ventricular angiograms. The overall mortality in all elective operations for cardiac pain resistant to medical treatment was 15·8%. 89% of survivors improved; 67% are pain-free. Exercise tolerance in survivors is increased by 135%, atrial pacing results are improved by 10%. Left ventricular end-diastolic pressure is unchanged. Left ventricular function on angiography is improved. The improvement in left ventricular function assessed objectively correlates positively with vein-graft patency, as does freedom from angina pectoris.     

Atrial pacing, the forgotten pacing mode

In patients with sick sinus syndrome and normal atrioventricular conduction, physiological pacing can be accomplished with either a single chamber atrial pacemaker AAI/R or a dual chamber pacemaker DDD/R. The single chamber device has the advantages of simpler implantation and lower initial costs, while the dual chamber device offers protection in case atrioventricular conduction disturbances develop in the future. When rigorous attention is paid to the pre-implantation selection criteria, the incidence of reported second- or third-degree atrioventricular block varied between 0.4 and 1.8% per annum. Medical practice, however, has shifted to predominant implantation of DDD/R pacemakers in more than 95% of patients with sick sinus syndrome. Recent publications have reported an increase in left atrial diameter, decrease in left ventricular fractional shortening and increased incidence of atrial fibrillation in patients with DDD/R pacing as compared with patients with single chamber atrial devices. These changes were proportional to the percentage of ventricular paced beats. New algorithms in dual chamber devices have been developed in order to minimise ventricular stimulation. These are being evaluated at present. In my opinion there is still a place for atrial pacing in selected patients with sick sinus syndrome with a minimum risk of developing complete atrioventricular block. (Neth Heart J 2008;16(suppl 1): S25-S27.)     

Ventriculo-atrial gradient due to first degree atrio-ventricular block: a case report

Background

Isolated, asymptomatic first degree AV block with narrow QRS has not prognostic significance and is not usually treated with pacemaker implantation. In some cases, yet, loss of AV synchrony because of a marked prolongation of the PR interval may cause important hemodynamic alterations, with subsequent symptoms of heart failure. Indeed, AV synchrony is crucial when atrial systole, the "atrial kick", contributes in a major way to left ventricular filling, as in case of reduced left ventricular compliance because of aging or concomitant structural heart disease.

Case presentation

We performed a trans-septal left atrium catheterization aimed at evaluating the entity of a mitral valve stenosis in a 72-year-old woman with a marked first-degree AV block, a known moderate aortic stenosis and NYHA class III symptoms of functional deterioration. We occurred in a deep alteration in cardiac hemodynamics consisting in an end-diastolic ventriculo-atrial gradient without any evidence of mitral stenosis. The patient had a substantial improvement in echocardiographic parameters and in her symptoms of heart failure after permanent pacemaker implantation with physiological AV delay.

Conclusion

We conclude that if a marked first degree AV block is associated to instrumental signs or symptoms of heart failure, the restoration of an optimal AV synchrony, achieved with dual-chamber pacing, may represent a reasonable therapeutic option leading to a consequent clinical improvement.     

Clinical Experience with the Elema Vario Pacemaker

Early problems after implantation of an endocardial electrode for permanent pacing occur in many patients. Difficulties can be anticipated in many of these patients and their management made much easier by a knowledge of the daily endocardial threshold obtained in patients with an implanted Elema Verio pacing unit by a simple non-invasive technique using a magnet and electrocardiogram. Twenty patients are described in whom permanent pacing with an Elema Vario unit was undertaken. The practical advantages of this unit can be readily seen in the patient who developes exit block or in the patient with obstructive airways disease, in whom frequent coughing or right ventricular hypertrophy may make stable electrode placement difficult. The chief advantage of the Elema Vario pacemaker is the extreme simplicity with which knowledge of the endocardial threshold can be obtained.     

Tailoring cardiac resynchronisation therapy to non-left bundle branch block: Successful cardiac resynchronisation for right bundle branch block with left posterior fascicular block without implantation of a left ventricular lead

Despite advances, cardiac resynchronisation therapy (CRT) remains fundamentally orientated to the dyssynchrony of left bundle branch block (LBBB), in which septo-lateral electrical and mechanical delays predominate. For non-LBBB patients response rates to conventional CRT are lower and mortality and rehospitalisation rates are not reduced. Despite this, alternative approaches which tailor CRT to the differing dyssynchrony patterns of non-LBBB have yet to be developed. In the specific non-LBBB subgroup of right bundle branch block (RBBB) with left posterior fascicular block (LPFB), ventricular conduction via the left anterior fascicle results in a unique early lateral, and late septal depolarisation, or lateral to septal left ventricular (LV) delay, an electrical sequence which is followed mechanically. This latero-septal delay is somewhat the reverse of LBBB and was overcome by fusing right ventricular (RV) septal pacing with intrinsic conduction via the left anterior fascicle, achieving successful resynchronisation without implantation of a left ventricular lead. A stable fusion pattern was achieved via the ‘Negative AV Hysteresis with Search’ algorithm (Abbott, St Paul, Minnesota). Improvement in all standard CRT response indices was achieved at 3 months: QRS duration was reduced from 153 to 106 ms, ejection fraction increased from 14 to 32%, and LV end-systolic and end-diastolic diameters reduced by 19% and 12.5% respectively. NYHA class improved from III-IV to class II. Cardiac resynchronisation for RBBB with LPFB can be successfully achieved with a standard pacemaker or defibrillator without left ventricular lead implantation by fusing RV septal-only pacing with intrinsic conduction.     

Virtual reality 3D echocardiography in the assessment of tricuspid valve function after surgical closure of ventricular septal defect

Background

Chronic right ventricular apical pacing may have detrimental effect on left ventricular function and may promote to heart failure in adult patients with left ventricular dysfunction.

Methods

A group of 99 pediatric patients with previously implanted pacemaker was studied retrospectively. Forty-three patients (21 males) had isolated congenital complete or advanced atrioventricular block. The remaining 56 patients (34 males) had pacing indication in the presence of structural heart disease. Thirty-two of them (21 males) had isolated structural heart disease and the remaining 24 (13 males) had complex congenital heart disease. Patients were followed up for an average of 53 ± 41.4 months with 12-lead electrocardiogram and transthoracic echocardiography. Left ventricular shortening fraction was used as a marker of ventricular function. QRS duration was assessed using leads V₅ or II on standard 12-lead electrocardiogram.

Results

Left ventricular shortening fraction did not change significantly after pacemaker implantation compared to preimplant values overall and in subgroups. In patients with complex congenital heart malformations shortening fraction decreased significantly during the follow up period. (0.45 ± 0.07 vs 0.35 ± 0.06, p = 0.015). The correlation between the change in left ventricular shortening fraction and the mean increase of paced QRS duration was not significant. Six patients developed dilated cardiomyopathy, which was diagnosed 2 months to 9 years after pacemaker implantation.

Conclusion

Chronic right ventricular pacing in pediatric patients with or without structural heart disease does not necessarily result in decline of left ventricular function. In patients with complex congenital heart malformations left ventricular shortening fraction shows significant decrease.     

Pacing in congestive heart failure

Despite the major advances in medical drug therapy, heart failure remains a syndrome associated with high mortality and morbidity. Biventricular or left ventricular (LV) short atrioventricular (AV) delay pacing is being tested in congestive heart failure patients with left bundle branch block. The aim is to resynchronise the dyscoordinate LV contraction. A number of studies are underway, but it is clear that while some patients respond remarkably, this is highly variable. Accurate identification of patients likely to benefit will be crucial. The mechanism of benefit is unclear. A greater understanding of the physiological consequences of pacing will be necessary to accurately identify these patients.     

The effects of right ventricular apical pacing on left ventricular function. Stimulation of the right ventricular apex: should it still be the gold standard?

Current pacing practice is undergoing continuous and substantial changes. Initially pacing had an exclusively palliative role, since it was reserved for patients developing complete heart block or severe symptomatic bradycardia. With the appearance of novel pacing indications such as pacing for heart failure and atrial fibrillation, the effect of pacing site on cardiac function has become a critically important issue and a subject for consideration. It seems that the classical pacing site in the right ventricular apex is no longer the gold standard because of possible disadvantageous effects on cardiac function. The aim of this review article is to discuss the effect of right ventricular apical pacing on cardiac function including cellular and hemodynamic changes. We also aim to discuss the role of alternative pacing sites in the light of cardiac function.