Effects of closed-loop stimulation vs. DDD pacing on haemodynamic variations and occurrence of syncope induced by head-up tilt test in older patients with refractory cardioinhibitory vasovagal syncope: the Tilt test-Induced REsponse in Closed-loop Stimulation multicentre, prospective, single blind, randomized study

AIMS

Closed-loop stimulation (CLS) seemed promising in preventing the recurrence of vasovagal syncope (VVS) in patients with a cardioinhibitory response to head-up tilt test (HUTT) compared with conventional pacing. We hypothesized that the better results of this algorithm are due to its quick reaction in high-rate pacing delivered in the early phase of vasovagal reflex, which increase the cardiac output and the blood pressure preventing loss of consciousness.

METHODS AND RESULTS

This prospective, randomized, single-blind, multicentre study was designed as an intra-patient comparison and enrolled 30 patients (age 62.2 ± 13.5 years, males 60.0%) with cardioinhibitory VVS, carrying a dual-chamber pacemaker incorporating CLS algorithm. Two HUTTs were performed one week apart: one during DDD-CLS 60-130/min pacing and the other during DDD 60/min pacing; patients were randomly and blindly assigned to two groups: in one the first HUTT was performed in DDD-CLS (n = 15), in the other in DDD (n = 15). Occurrence of syncope and haemodynamic variations induced by HUTT was recorded during the tests. Compared with DDD, DDD-CLS significantly reduced the occurrence of syncope induced by HUTT (30.0% vs. 76.7%; P < 0.001). In the patients who had syncope in both DDD and DDD-CLS mode, DDD-CLS significantly delayed the onset of syncope during HUTT (from 20.8 ± 3.9 to 24.8 ± 0.9 min; P = 0.032). The maximum fall in systolic blood pressure recorded during HUTT was significantly lower in DDD-CLS compared with DDD (43.2 ± 30.3 vs. 65.1 ± 25.8 mmHg; P = 0.004).

CONCLUSION

In patients with cardioinhibitory VVS, CLS reduces the occurrence of syncope induced by HUTT, compared with DDD pacing. When CLS is not able to abort the vasovagal reflex, it seems to delay the onset of syncope.

Persistence of ICD indication at the time of replacement in patients with initial implant for primary prevention indication: Effect on subsequent ICD therapies

Background

Indication to implantable cardioverter defibrillator (ICD) for primary prevention of sudden death relies on left ventricular ejection fraction (LVEF). We measured the proportion of patients in whom indication to ICD persisted at the time of generator replacement (GR) and searched for predictors of appropriate therapies after GR.

Methods

We identified all consecutive patients who had received an ICD at our hospital, for LVEF ≤35% and no previous arrhythmias or unexplained syncope. Then, we included the 166 patients who outlived their first device and underwent GR.

Results

At the time of GR (mean follow-up 59 ± 20 months), ICD indication (i.e. LVEF ≤35% or previously treated ventricular arrhythmias) persisted in 114 (69%) patients. After GR, appropriate ICD therapies were delivered in 30 (26%) patients with persistent ICD indication and in 12 (23%) of the remaining patients (p = 0.656). Nonetheless, the annual rate of therapies was higher in the first group (1.08 versus 0.53 events/year; p < 0.001), as well as the rate of inappropriate therapies (0.03 versus 0 events/year; p = 0.031). The only independent predictor of appropriate ICD therapies after GR was the rate of shocks received before replacement (Hazard Ratio: 1.41; 95% confidence interval: 1.01–1.96; p = 0.041).

Conclusion

In heart failure with reduced LVEF, ICD indication persisted at the time of GR in 69% of patients. However, even in the absence of persistent ICD indication at GR, the risk of recurrence of arrhythmic events was not null.

Right ventricular septal pacing: Safety and efficacy in a long term follow up

AIM: To evaluate the safety and efficacy of the permanent high interventricular septal pacing in a long term follow up, as alternative to right ventricular apical pacing.

METHODS: We retrospectively evaluated: (1) 244 patients (74 ± 8 years; 169 men, 75 women) implanted with a single (132 pts) or dual chamber (112 pts) pacemaker (PM) with ventricular screw-in lead placed at the right ventricular high septal parahisian site (SEPTAL pacing); (2) 22 patients with permanent pacemaker and low percentage of pacing (< 20%) (NO pacing); (3) 33 patients with high percentage (> 80%) right ventricular apical pacing (RVA). All patients had a narrow spontaneous QRS (101 ± 14 ms). We evaluated New York Heart Association (NYHA) class, quality of life (QoL), 6 min walking test (6MWT) and left ventricular function (end-diastolic volume, LV-EDV; end-systolic volume, LV-ESV; ejection fraction, LV-EF) with 2D-echocardiography.

RESULTS: Pacing parameters were stable during follow up (21 mo/patient). In SEPTAL pacing group we observed an improvement in NYHA class, QoL score and 6MWT. While LV-EDV didn’t significantly increase (104 ± 40 mL vs 100 ± 37 mL; P = 0.35), LV-ESV slightly increased (55 ± 31 mL vs 49 ± 27 mL; P = 0.05) and LV-EF slightly decreased (49% ± 11% vs 53% ± 11%; P = 0.001) but never falling < 45%. In the RVA pacing control group we observed a worsening of NYHA class and an important reduction of LV-EF (from 56% ± 6% to 43% ± 9%, P < 0.0001).

CONCLUSION: Right ventricular permanent high septal pacing is safe and effective in a long term follow up evaluation; it could be a good alternative to the conventional RVA pacing in order to avoid its deleterious effects.

An anomalous case of acute coronary syndrome: the unexpected autoimmune duo

: Acute coronary syndrome represents one of the most common causes of admittance to emergency rooms in Western countries. Despite being in the majority of cases the mirror of coronary atherosclerosis, more rare causes could be hidden beyond this presentation, whose identification is often crucial for patients' outcome. We hereby present the case of a 44-year-old woman, with a history of relapsing-remitting multiple sclerosis in treatment with natalizumab, who was admitted to our division for an acute coronary syndrome. At arrival, anaemia and severe thrombocytopenia were observed; thus, no antiplatelet agent was administered. Within a few hours, aphasia occurred. Clinical presentation and the identification of schistocytes at blood smear led to the suspicion of thrombotic thrombocytopenic purpura, which was then confirmed by laboratory analysis. Immediate high-dose steroids and plasma exchange allowed discharging of the patient within a few days without neurological or cardiac sequelae.

Transient hyperkalemia-induced T-wave oversensing as a cause of inappropriate ICD discharges

The present case describes a patient with an implantable cardioverter-defibrillator (ICD) who reported several ICD inappropriate discharges due to transient T-wave oversensing in the setting of acute hyperkalemia. T-wave oversensing was detected only at telemetry interrogation while T-wave amplitude at surface 12-lead electrocardiogram was normal. Oversensing was abolished by reducing potassium levels and by device reprogramming. This case report underscores the importance of identifying a potentially reversible cause of ICD inappropriate discharges and the utility of careful review of stored electrograms. <Learning objective: This case report underscores the importance of understanding the diversity of causes of implantable cardioverter-defibrillator malfunctioning and the utility of careful review of stored electrograms.>.

Evaluation of atrial function after surgical ablation of atrial fibrillation: a Speckle tracking study

AIM

AIM of our study was to assess atrial function in patients who underwent atrial fibrillation (AF) surgical ablation by a novel echocardiographic technique (speckle tracking).

METHODS

From February 2006 to April 2008, in 11 consecutive pts with paroxysmal or persistent AF (6 males, mean age 69.6±9.7 years) undergoing cardiac surgery, concomitant AF surgical ablation was performed with bipolar radiofrequency clamp (Cobra_Bipolar® system). These pts, all in stable sinus rhythm (SR), were echoed after a mean follow-up of 14.6±9.3 months from surgery. Speckle tracking was used to estimate global LA strain, peak strain and the standard deviation of the time-to-peak (% of R-R' interval) of the deformation of 6 segments identified along the septum, the roof and the lateral wall of LA in a 4-chamber view.

RESULTS

These patients showed a mild LA enlargement (mean volume 43.4±11.6 mL/sqm). In 5 of them (45.4%) no A waves were detected on MPWD and pulmonary venous flow, but speckle tracking showed preserved atrial function with a mean global strain of 5.5 ± 3.3 %, a mean peak strain of 10.4 ± 5.7 % and a TP-SD of 15.1±8.7 ms.

CONCLUSION

Our study seems to show that surgical AF ablation has a lower impact on atrial function in comparison with data from literature about percutaneous catheter ablation. This is probably related to an higher sensitivity of this type of echocardiography evaluation, but this finding must be confirmed by other trials.

Stable ventricular fibrillation in a heterotopic heart transplant recipient

We present an unusual case of ventricular fibrillation in a conscious patient symptomatic for chest pain and shortness of breath. Almost 20 years ago he underwent heterotopic cardiac transplantation for the treatment of severe idiopathic cardiomyopathy. In the precyclosporine era, this technique was extremely useful because of the high rate of graft rejection in which the maintenance of the native heart could prevent patient death. To date, with the improvements in immunosuppressive therapy, it is generally reserved to a specific subset of conditions. A coronary angiography and a cardiac MRI confirmed the diagnosis. Six months follow-up ECG was unchanged suggesting the persistence of a double heart rhythm in the same body.

Ventricular fibrillation as primary presentation of takotsubo cardiomyopathy after complicated cesarean delivery

Takotsubo cardiomyopathy typically affects post-menopausal women under severe psychological or physical stress; it also has been reported to develop after medical procedures or surgery. We herein report the rare case of a 30-year-old woman who presented with an episode of ventricular fibrillation after a very complicated cesarean delivery and was successfully resuscitated. Subsequent electrocardiography and echocardiography showed a typical Takotsubo pattern. Within 3 wk, left ventricular systolic function returned to normal.

Analysis of electrical and mechanical left atrial properties in patients with persistent atrial fibrillation

The study of left atrial (LA) mechanical function during atrial fibrillation (AFib) can provide valuable information, particularly if such profiling is related to the cavity electrical substrate and conveys prognostic information. To assess if there is any relation between LA mechanical and electrical asynchrony and if such evaluation can be of interest in stratifying AFib patients. 50 patients with persistent AFib who underwent electrical cardioversion (CV) were evaluated with pre-CV atrial electrograms (AEGs). Electrical asynchrony was classified according to Wells' patterns of AEGs, ranging from most organized (I) to most dispersed (III) one. LA mechanical asynchrony was addressed by transthoracic 2D-speckle-tracking echo and quantified according to time-to-peak standard deviation (TP-SD) of wall strains and their peak values (PS) before CV, after 24 h, at 1 month. Pre-CV a linear, inverse relation between TP-SD and PS (p < 0.001) and a direct linear relation between TP-SD and Wells' classes (p = 0.04) were observed. With sinus rhythm TP-SD decreased (p = 0.023) and PS increased (p < 0.001), suggesting improved LA mechanical milieu. A multivariate analysis, testing the effects of baseline variables in predicting post-CV recurrence of AFib, revealed that amount of TP-SD variation pre/24 h post-CV was the only independent predictor at 6 months (p = 0.046). Speckle tracking-derived LA parameters can describe LA wall forces during AFib, categorizing the asynchronous mechanistic profile of AFib that correlates with the degree of the dispersed LA electrical activity. The amount of changes in LA mechanical asynchrony pre/post-CV seems to have prognostic relevance in predicting SR maintenance.

Inappropriate asystole detection in early postoperative phase after loop recorder implantation

The implantable loop recorder is a useful diagnostic tool for patients with unexplained syncope. The capability to automatically detect and store arrhythmic events, implemented in the last generations of these devices, can further improve the diagnostic yield, but this feature can be compromised by inappropriate detection of false arrhythmias. We herein report the case of a patient in which several inappropriate activations of long-lasting asystole occurred in the two days following the implant, probably because of an intermittently loose contact between the device and subcutaneous tissue for a small pocket haematoma.

Diagnosis, management, and outcomes of patients with syncope and bundle branch block

Aims

Although patients with syncope and bundle branch block (BBB) are at high risk of developing atrio-ventricular block, syncope may be due to other aetiologies. We performed a prospective, observational study of the clinical outcomes of patients with syncope and BBB following a systematic diagnostic approach.

Methods and results

Patients with ≥1 syncope in the last 6 months, with QRS duration ≥120 ms, were prospectively studied following a three-phase diagnostic strategy: Phase I, initial evaluation; Phase II, electrophysiological study (EPS); and Phase III, insertion of an implantable loop recorder (ILR). Overall, 323 patients (left ventricular ejection fraction 56 ± 12%) were studied. The aetiological diagnosis was established in 267 (82.7%) patients (102 at initial evaluation, 113 upon EPS, and 52 upon ILR) with the following aetiologies: bradyarrhythmia (202), carotid sinus syndrome (20), ventricular tachycardia (18), neurally mediated (9), orthostatic hypotension (4), drug-induced (3), secondary to cardiopulmonary disease (2), supraventricular tachycardia (1), bradycardia–tachycardia (1), and non-arrhythmic (7). A pacemaker was implanted in 220 (68.1%), an implantable cardioverter defibrillator in 19 (5.8%), and radiofrequency catheter ablation was performed in 3 patients. Twenty patients (6%) had died at an average follow-up of 19.2 ± 8.2 months.

Conclusion

In patients with syncope, BBB, and mean left ventricular ejection fraction of 56 ± 12%, a systematic diagnostic approach achieves a high rate of aetiological diagnosis and allows to select specific treatment.

Usefulness of hemodynamic sensors for physiologic cardiac pacing in heart failure patients

The rate adaptive sensors applied to cardiac pacing should respond as promptly as the normal sinus node with an highly specific and sensitive detection of the need of increasing heart rate. Sensors operating alone may not provide optimal heart responsiveness: central venous pH sensing, variations in the oxygen content of mixed venous blood, QT interval, breathing rate and pulmonary minute ventilation monitored by thoracic impedance variations, activity sensors. Using sensors that have different attributes but that work in a complementary manners offers distinct advantages. However, complicated sensors interactions may occur. Hemodynamic sensors detect changes in the hemodynamic performances of the heart, which partially depends on the autonomic nervous system-induced inotropic regulation of myocardial fibers. Specific hemodynamic sensors have been designed to measure different expression of the cardiac contraction strength: Peak Endocardial Acceleration (PEA), Closed Loop Stimulation (CLS) and TransValvular Impedance (TVI), guided by intraventricular impedance variations. Rate-responsive pacing is just one of the potential applications of hemodynamic sensors in implantable pacemakers. Other issues discussed in the paper include: hemodynamic monitoring for the optimal programmation and follow up of patients with cardiac resynchronization therapy; hemodynamic deterioration impact of tachyarrhythmias; hemodynamic upper rate limit control; monitoring and prevention of vasovagal malignant syncopes.

Future easy and physiological cardiac pacing

The right atrial appendage (RAA) and right ventricular apex (RVA) have been widely considered as conventional sites for typical dual-chamber atrio-ventricular cardiac (DDD) pacing. Unfortunately conventional RAA pacing seems not to be able to prevent atrial fibrillation in DDD pacing for tachycardia-bradycardia syndrome, and the presence of a left bundle branch type of activation induced by RVA pacing can have negative effects. A new technology with active screw-in leads permits a more physiological atrial and right ventricular pacing. In this review, we highlight the positive effects of pacing of these new and easily selected sites. The septal atrial lead permits a shorter and more homogeneous atrial activation, allowing better prevention of paroxysmal atrial fibrillation. The para-Hisian pacing can be achieved in a simpler and more reliable way with respect to biventricular pacing and direct Hisian pacing. We await larger trials to consider this "easy and physiological pacing" as a first approach in patients who need a high frequency of pacing.

Do electrical parameters of the cardiac cycle reflect the corresponding mechanical intervals as the heart rate changes?

AIMS

The evoked QT interval can be detected beat by beat through an implanted pacing system. The correlation between the right ventricular paced QT interval and the left ventricular systolic interval is not known. The aim of our study was to collect data on the correlation between QT and systolic and diastolic indexes at different heart rates in patients with dual-chamber rate-responsive pacemakers.

METHOD AND RESULTS

The study involved 13 patients [67 +/- 9 years; ejection fraction (EF) 52 +/- 10%] with standard indication for dual-chamber pacing. Patients were evaluated at rest in the supine position. The AV delay was set at 130 ms, and the pacing rate was increased from 90 to 130 bpm (10 bpm steps for 3 min). At the end of each 3 min step, QT intervals were automatically evaluated in real time by means of pacemaker telemetry. We also evaluated heart performance by means of echo-2D (end-diastolic/end-systolic volumes, EF) and echo-Doppler measurements [left ventricular ejection time (LVET) and diastolic filling time (LVDFT), aortic velocity time integral, and systolic volume] and systemic arterial pressure. The QT interval progressively decreased from 330 +/- 20 to 280 +/- 10 ms as the pacing rate was increased from 90 to 130 bpm. The correlation between the QT interval and LVET as a function of the pacing rate was R(2) = 0.966, indicating a good and relatively parallel trend in these two parameters. The correlation between RR-QT (reflecting electrical diastole) and LVDFT (reflecting mechanical diastole) was R(2) = 0.975. The index LVET/QT (ratio between mechanical and electrical systole) was constant in the range 90-120 bpm, but significantly decreased at 130 bpm: the mechanical LVET shortens more than the electrical QT does at the highest heart rates.

CONCLUSION

In paced patients at rest and during artificially increased heart rates, QT interval dynamics is closely correlated with changes in ejection time, thus constituting an electrical parameter of systolic time. A similar correlation exists between RR-QT, as a diastolic electrical interval, and the DFT.

Left ventricular torsion in paced patients

BACKGROUND

In healthy people the left ventricle presents a counter-clockwise apical rotation and a clockwise basal rotation ending in late systole. In early systole (during isovolumic contraction) there is a fast and inverse rotation (counter-clockwise at the base and clockwise at the apex). This opposite rotation between apex and base produces the systolic torsion of the left ventricle. The effect of permanent conventional pacing on this torsion is little known.

OBJECTIVES

The aim of this study was to assess, by speckle tracking echocardiography, left ventricular rotation and torsion in patients conventionally paced at the apex of the right ventricle.

METHODS

Left ventricular apical and basal rotation and the consequent torsion were evaluated by means of speckle tracking echocardiography, in 13 paced patients, without ischemic or valvular disease, and in 17 healthy participants. Left ventricular dyssynchrony was evaluated by means of temporal uniformity of strain.

RESULTS

In the paced group there was a significant reduction in early-systolic clockwise torsion (-0.4 degrees +/- 1.2 vs. -1.5 degrees +/- 1.6; P = 0.04), and in late-systolic counter-clockwise torsion (15.1 degrees +/- 4.3 vs. 19.1 degrees +/- 5.5; P = 0.03). Circumferential temporal uniformity of strain averaged significantly lower in paced patients.

CONCLUSIONS

Conventional pacing from the apex of the right ventricle alters both the torsional mechanic and the synchrony of the left ventricle.

Ventricular fibrillation in acute mitral valve insufficiency caused by chordae tendineae rupture: report of a surgically corrected case

In this report, we present the case of a previously healthy 80-year-old woman who was referred to surgery after a cardiac arrest due to ventricular fibrillation successfully resuscitated; the following evaluation revealed acute mitral regurgitation due to chordae tendineae rupture. After mitral valve repair, a single-chamber cardioverter-defibrillator was implanted for secondary prevention of sudden cardiac death. After 16 months of follow-up, the patient is asymptomatic without any further episodes of ventricular arrhythmias reported, underlying the pivotal role of mitral valve repair in the prevention of potentially lethal ventricular arrhythmias.

Transient trifascicular block complicating myocardial contusion after blunt chest trauma: a case report

Cardiac contusion may be frequently found in patients with blunt chest trauma, and it presents clinically as a spectrum of injuries of varying severity, including transient disorders of impulse formation and propagation. A rare observation of transient trifascicular block in a previously fit 32-year-old man involved in a car accident is reported. The importance of ECG monitoring and biochemical assessment of markers to unmask myocardial contusion is discussed.

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.

[Electrical storms in patients with implantable cardioverter-defibrillator: incidence and clinical management]

BACKGROUND

Electrical storm in implantable cardioverter-defibrillator (ICD) recipients is a dramatic experience for the patient and a hard emergency for the cardiology team. The aim of our study was to evaluate the incidence and the clinical significance of electrical storm in a standard population of ICD patients.

METHODS

We considered retrospectively 262 consecutive ICD patients (86% males, mean age 65+/-10.7 years). Patients were divided into three groups: 88 patients without appropriate ICD therapy (group A); 140 patients with isolated ICD therapies (group B); 34 patients with electrical storm episodes (> or = 3 appropriate ICD therapies/24 h) (group C). Survival study (endpoint death) was performed for each group of patients.

RESULTS

There was no difference in age, sex, heart disease, ejection fraction or NYHA functional class among the three groups. ICD implant was performed for secondary prevention in 79% of group C patients and in 74.3 % of group B patients, but only in 39.8 % of group A patients (p < 0.0001). Mean follow-up was 31.1+/-29.8 months in group A, 55.1+/-38 months in group B, and 71.1+/-51.7 months in group C. The endpoint was reached by 16 patients (18%) of group A, by 53 patients (38%) of group B, and by 20 patients (58%) of group C. Comparison of the survival curves of the three groups did not show significant differences. In group C patients, 54 electrical storm episodes were recorded (mean 1.5/patient).

CONCLUSIONS

In our population of ICD patients, we observed electrical storm in 34 patients (12.9%). Survival in group with episodes of electrical storm was comparable to patients without electrical storm; thus, in our experience, electrical storm could not represent a negative prognostic factor.

Inappropriate implantable cardioverter-defibrillator discharges unrelated to supraventricular tachyarrhythmias

AIMS

The development of implantable cardioverter-defibrillators (ICDs) with QRS morphology discrimination and dual-chamber sensing capabilities has improved the differentiation of supraventricular from ventricular tachycardias (VTs). Inappropriate ICD discharges may result from extracardiac signals caused by electromagnetic interference (EMI), because of electric fields and leakage currents from domestic or medical electrical devices, damaged sensing leads, and various cardiac and extracardiac signals that mimic VT and/or ventricular fibrillation. The aim of our study was to determine retrospectively the incidence and clinical relevance of these ICD behaviours and offer possible therapeutic solutions.

METHODS AND RESULTS

We have observed inappropriate discharges unrelated to supraventricular arrhythmias in 13 (3.9%) of the 336 patients implanted with ICDs in our centre from 1989 to 2005. Seven patients received inappropriate shocks following exposure to external EMI: improperly grounded electric stove, electrically powered watering system, hydro-massage bath, electrical pruner, electrocautery current during cardiac surgery, transcutaneous electric nerve stimulation. In four patients, spurious discharges were related to internal noise of the ICD system from inappropriate lead connections. In two cases, erroneous antitachycardia therapy was delivered following different body signals oversensing (T-wave oversensing, wide QRS double-counting and myopotentials). In nine patients, non-invasive solutions prevented further inappropriate therapies (avoidance of EMI, malfunctioning atrial lead exclusion, ventricular sensing reprogramming). In four patients, surgical revision of the system was required (lead connections or position revision).

CONCLUSION

In our experience, inappropriate ICD discharges unrelated to supraventricular arrhythmias occurred in about 4% of ICD patients. A careful evaluation of clinical data and telemetric information (lead impedance, sensed R-wave, stored electrograms) is essential in order to understand the nature of inappropriate ICD discharges and to select the most appropriate solution.

Upgrade of a single chamber endo-epicardial to a triple chamber biventricular implantable cardioverter-defibrillator

In patients with heart failure implanted with conventional pacemakers, cardiac resynchronization therapy results in significant benefits. The upgrade of previously implanted devices to biventricular pacing may be technically challenging. We report one case of upgrade to biventricular pacing and describe the related technical implications and the therapeutic solutions adopted.

Prevention of ventricular desynchronization by permanent para-Hisian pacing after atrioventricular node ablation in chronic atrial fibrillation: a crossover, blinded, randomized study versus apical right ventricular pacing

OBJECTIVES

The aim of our study was to evaluate the feasibility, the safety, and hemodynamic improvements induced by permanent para-Hisian pacing in patients with chronic atrial fibrillation and narrow QRS who underwent atrioventricular (AV) node ablation.

BACKGROUND

Right ventricular apical pacing, inducing asynchronous ventricular contraction, may impair cardiac function; permanent para-Hisian pacing could preserve interventricular synchrony and improve left ventricular function.

METHODS

After AV node ablation, 16 patients were implanted with a dual-chamber pacemaker connected to a screw-in lead positioned in close proximity to the His bundle and to a right ventricular apical lead. Clinical and echocardiographic data were collected at baseline and after two randomized six-month periods (with para-Hisian and conventional pacing).

RESULTS

During para-Hisian pacing, the interventricular electromechanical delay improved as well (34 +/- 18 ms) as during right apical pacing (47 +/- 19 ms), p < 0.05. Para-Hisian pacing allowed an improvement in New York Heart Association functional class (1.75 +/- 0.4 vs. 2.33 +/- 0.6 at baseline and 2.5 +/- 0.4 during apical pacing, p < 0.05 for both), in quality-of-life score (16.2 +/- 8.7 vs. 32.5 +/- 15.0 at baseline, p < 0.05), and in the 6-min walk test (431 +/- 73 m vs. 378 +/- 60 m at baseline and 360 +/- 71 m during apical pacing, p < 0.5 for both). Mitral and tricuspid regurgitation improved during para-Hisian pacing (1.22 +/- 0.8 and 1.46 +/- 0.5 index, respectively, vs. 1.68 +/- 0.6 [p < 0.05] and 1.62 +/- 0.7 [p = NS] index at baseline, respectively), with a slight worsening during apical pacing (1.93 +/- 1 and 1.93 +/- 0.7 index, respectively, p < 0.05 for both).

CONCLUSIONS

Permanent para-Hisian pacing is feasible and safe. Compared with conventional right apical pacing, it allows an improvement in functional and hemodynamic parameters over long-term follow-up.

Ventricular capture by anodal pacemaker stimulation

This report describes the case of an 86-year-old male with syncopal paroxysmal 2:1 atrioventricular block and a single chamber VVI pacemaker programmed to bipolar sensing and unipolar pacing. After recurrence of syncope, a complete loss of ventricular capture with regular ventricular sensing was observed on ECG; fluoroscopic examination suggested perforation of the right ventricle by the helix of the implanted screw-in lead. Reprogramming the pacemaker to bipolar pacing/sensing resulted in regular ventricular capture and sensing, suggesting effective anodal stimulation from the ring electrode permitting complete non-invasive palliation.

Rate-responsive pacing regulated by cardiac haemodynamics

AIMS

Trans-valvular impedance (TVI) recording has been proposed for the assessment of cardiac haemodynamics, assuming an inverse relationship between TVI and ventricular volume. We checked whether the TVI sensor can drive the rate-responsive function of a cardiac pacemaker following changes in the inotropic regulation of the heart.

METHODS

An external DDD-R pacemaker (Ext Sophos by Medico, Padova, Italy) equipped with the TVI detecting system was tested in 30 patients on the implantation of conventional pacing leads for dual-chamber pacing. Pacing rate regulation was based on the relationship between the stroke volume and the end-diastolic volume, inferred from TVI data. After sensor calibration in basal conditions, beta-adrenergic stimulation was induced by i.v. administration of 2 microg/ml/min isoprenaline (isoproterenol) (IPN). The actual cardiac rate, the TVI waveform, the end-diastolic and systolic TVI in each cardiac cycle and the TVI-indicated rate were stored in memory as a function of time and down-loaded at the end of the session.

RESULTS

All patients with intrinsic atrial activity (28/30) showed a positive chronotropic response to IPN, coupled with a significant increase in end-diastolic TVI and a four-times larger increase in end-systolic TVI. The TVI inotropic index mirrored the sinus rate time-course, with a linear correlation between the two parameters (r(2)>0.7 in 25/28 cases). As a result, the TVI-indicated rate closely reproduced the sinus rate.

CONCLUSIONS

The study confirms the reliability of the haemodynamic information derived from TVI and supports its application in the regulation of rate-responsive pacing.

Closed loop stimulation in prevention of vasovagal syncope. Inotropy controlled pacing in vasovagal syncope (INVASY): a multicentre randomized, single blind, controlled study

OBJECTIVES

To determine whether dual-chamber rate-adaptive Closed Loop Stimulation (CLS) could prevent recurrence of Vasovagal Syncope (VVS).

BACKGROUND

During VVS, an increase in myocardial contractility associated with a reduction of ventricular filling produces an increase in baroreceptor afferent flow and a consequent decrease in the heart rate. The CLS algorithm is a form of rate-adaptive pacing, which responds to myocardial contraction dynamics, by measuring variations in right ventricular intracardiac impedance: during an incipient VVS it could increase paced heart rate and avoid bradycardia, arterial hypotension and syncope.

METHODS

Fifty patients (27 males, mean age 59+/-18 year) with severe and recurrent vasovagal syncope and positive Head Up Tilt Test (HUTT) with cardioinhibition, received a CLS pacemaker (INOS2, Biotronik GmbH Co., Germany). The primary end point was recurrence of two VVSs during a minimum of 1 year of follow-up. Randomization between DDD-CLS and DDI mode (40 bpm) pacing was performed only during the first stage of the study (first year): 9/26 randomized to DDI mode (control group) and 17/26 in DDD-CLS mode. All the 24 patients recruited in the second stage of the study (second year) were programmed in DDD-CLS mode.

RESULTS

Of the nine patients randomized to the DDI mode, seven had recurrences of syncope during the first year. At the end of the first year the nine patients were reprogrammed to the CLS mode and no syncope occurred after reprogramming. The 41 patients programmed to CLS had a mean follow-up of 19+/-4 months: none reported VVS, only four (10%) reported occasional presyncope and their quality of life greatly improved. Positive HUTT at the end of the first year failed to predict the clinical response to CLS pacing.

CONCLUSIONS

The study demonstrates the effectiveness of CLS pacing in preventing cardioinhibitory VVS. A possible placebo effect of pacemaker implantation occurred in 22% of patients.

Primary hyperparathyroidism and arrhythmic storm in a patient with an implantable cardioverter defibrillator for primary prevention of sudden death

A case of a patient with an automatic cardioverter defibrillator (ICD) and recurrent ventricular arrhythmic storms related to primary hyperparathyroidism and hypercalcaemia is reported: medical therapy was ineffective and only surgical resection of the parathyroid adenoma resolved this complex clinical condition.

Twiddler's syndrome and pectoral stimulation in a patient with dual-site unipolar atrial pacing

Twiddler's syndrome is a rare condition of pacemaker rotation; when associated with unipolar pacing it could provoke extracardiac muscular stimulation. We report a case of an obese woman who unintentionally reversed her triple-chamber, dual-site unipolar atrial pacemaker, implanted for the prevention of paroxysmal atrial fibrillation. The extracardiac pectoral stimulation was due to unipolar atrial stimulation. The polarity mode was not programmable and output reduction was unsuccessful. Thus, the problem was resolved noninvasively by means of external manual rotation of the pacer. At 24 months of follow-up, the patient was still free of symptoms.

The DDDR closed loop stimulation for the prevention of vasovagal syncope: results from the INVASY prospective feasibility registry

BACKGROUND

The contraction dynamics of the ventricular myocardium are affected before and during vasovagal fainting suggesting that the Closed Loop Stimulation (CLS) pacemaker could be useful for the treatment of these patients. CLS is a new concept of heart rate modulation in cardiac pacing. The pacemaker INOS(2) CLS (Biotronik, Germany) derives its information for heart rate optimization from myocardial contraction dynamics, by measuring right ventricular intracardiac impedance. The pacemaker becomes an integral part of the circulatory regulation and, therefore, reacts appropriately to different cardiovascular demands.

METHODS

In a prospective registry, 34 patients with a history of recurrent vasovagal syncopal events were implanted with INOS(2) DDDR CLS pacemakers. The aim of the study was to evaluate both long term clinical outcome, including the first recurrence of syncope, with DDDR-CLS pacing and acute precipitation of vasovagal fainting with DDDR-CLS mode compared with DDD during head up tilt testing.

RESULTS

During a follow up period of 12-50 months, 30 patients experienced no further syncopal events in daily life; 1 patient had no syncope but night palpitations, which were eliminated by pacemaker reprogramming; 2 patients had presyncopal episodes but not syncopes; 3 syncopal recurrences occurred in one patient in chronic atrial fibrillation, possibly not an ideal candidate for implantation.

CONCLUSIONS

Further studies for detailed understanding of the preventive mechanism of DDDR-CLS pacing in vasovagal syncope are warranted. A randomized multicentre prospective new study (INotropy controlled pacing in VAsovagal SYncope: INVASY) is now in progress to confirm the beneficial effect of DDDR-CLS pacing in a larger group of patients with recurrent vasovagal syncope.

[Myocardial revascularization may resolve arrhythmic warm-up in patients with implantable cardioverter-defibrillator: 2 case reports]

Patients with ventricular arrhythmias and coronary artery disease may have a poor clinical outcome because of an increased risk of sudden cardiac death. In these patients therapeutic approaches include two main strategies: automatic implantable cardioverter-defibrillator (ICD) and antiarrhythmic drugs (when left ventricular function is preserved). Patients with arrhythmic warm-up sustained by ischemic attacks may be stabilized after percutaneous or surgical revascularization. We report the cases of 2 ICD patients, in whom the correction of myocardial ischemia was successful in preventing further ICD discharges. In the first patient with known coronary artery disease (previous acute myocardial infarction and left ventricular ejection fraction 30%) a sudden arrhythmic warm-up was reported with 70 ICD discharges in 24 hours; the patient underwent coronary artery bypass surgery and only few isolated episodes of ventricular tachycardia were observed during the following 34 months. In the second patient with a history of dorsal acute myocardial infarction and two previous interventions of coronary artery bypass graft surgery, we observed a sudden and unexpected arrhythmic instabilization with several ICD discharges. After percutaneous transluminal angioplasty of a graft stenosis, the clinical situation was stabilized and no more ICD activations were observed during the follow-up. In selected patients arrhythmic warm-up can rely on an ischemic substrate, then a careful re-evaluation for ischemia is mandatory in order to resolve the situation.

Implantable cardioverter defibrillators and cellular telephones: is there any interference?

The aim of our study was to consider cellular telephone interference using different cellular telephones and implantable cardioverter defibrillator (ICD) models. Thirty (26 men, 4 women) patients with ICDs were considered during follow-up. The ICD models were: Telectronics (7), CPI (7), Medtronic (7), Ventritex (5), and Ela Medical (4). All patients were monitored with surface ECG; permanent telemetric endo-ECG monitoring was activated. Then, the effect of two different European telephone systems were tested: TACS system (Sony CM-R111, 2W power) and GSM system (Motorola MG1-4A11, 2 W power). For both systems, the effect during call, reception, active conversation (dialogue), and passive conversation (listening) were observed. Cellular telephones were located first in contact with the programming head, then near the leads system, and lastly, in the hands of the patient. At the end of the evaluations, memories were interrogated again to check for false arrhythmia detections. In five of these patients during arrhythmia induction at device implant (first implant or ICD replacement), we also evaluated possible interference between cellular telephones in the reception phase and the ventricular fibrillation detection phase of the ICD. All evaluated models showed significant noise in the telemetric transmission when the cellular telephone (both TACS and GSM) was located near the ICD and the programming head; noise was particularly significant during call and reception, in most cases leading to loss of telemetry. No false arrhythmia detections have been observed during tests with cellular telephones located on the ICDs. During tests performed with cellular telephones located near the leads or in the hands of patients, no telemetric noises orfalse arrhythmia detections were observed. During induced ventricularfibrillation and cellular telephones in reception mode near the device, the arrhythmia recognition was always correct and not delayed. In conclusion, present ICD models seem to be well protected from electromagnetic interference caused by European cellular telephones (TACS and GSM), without under-/oversensing of ventricular arrhythmias. However, cellular telephones disturb telemetry when located near the programming head. ICD patients should not be advised against the use of cellular telephones, but it has to be avoided during ICD interrogation and programming.

[Intracardiac ectopic thyroid: a report of a clinical case with a long-term follow-up]

We describe the prolonged follow-up of a 64-year-old female patient, with an ectopic intracardiac thyroid gland. The mass was first detected 14 years ago, during a routine echocardiographic examination. The patient suffered from episodes of palpitation and cardiac auscultation revealed a systolic murmur. At cardiac surgery a right ventricular mass penetrating most of the interventricular septum was found. The mass was also prolapsing into the pulmonary infundibulum and could not be removed. On histopathology examination, the presence of a normal tissue was demonstrated. Two main clinical events characterized the prolonged follow-up: the gradual development of a massive tricuspid insufficiency, probably due to the strict anatomic relationship between the septal tricuspid papillary muscle and the mass itself; frequent supraventricular arrhythmias, partially refractory to different pharmacologic regimens, which could be ascribed to the chronic overload of the right atrium. The mass size has been stable over the years, and no thyroid hormone derangement was ever found.

[Dual-chamber DDD pacing in NYHA III-IV functional class dilated cardiomyopathy: short and middle-term evaluation]

Effectiveness of dual-chamber pacing in patients with dilated cardiomyopathy is still controversial. Our study was performed: to select the most favorable individual atrioventricular (AV) delay; to compare hemodynamic short-term effects in each patient after 2 periods of DDD pacing and sinus rhythm (AV spontaneous); to assess hemodynamic long-term (1 year) effects after DDD pacing at optimum AV delay. In 1996, 9 patients (7 men, 2 women; mean age 69 +/- 5 years) with dilated cardiomyopathy (5 idiopathic, 4 ischemic), NYHA functional class III-IV, ejection fraction < 30%, end-diastolic volume > 60 ml/m2, mitral regurgitation +2/+3, PR interval > or = 200 ms, were enrolled. All patients were implanted with DDD pacemakers and monitored for: ejection fraction and end-diastolic volume (measured by echocardiography and radionuclide angiography); clinical conditions; exercise tolerance and maximum oxygen consumption (by Weber exercise protocol); neurohormonal activity (plasma renin, aldosterone, atrial natriuretic factor). Data were recorded: before DDD implantation; after 2 randomized, single-blind periods of 3 months in VVI mode (at ventricular "sentinel" rate of 50 b/min) and in DDD mode with the optimum AV delay, corresponding for each patient to the minimum end-diastolic volume measured by radionuclide angiography and to the highest cardiac output recorded by echocardiography; after 6 months of DDD pacing with most favorable AV delay. Three more patients died 6 months after (between sixth and twelfth month of follow-up), due to refractory heart failure; 1 patient dropped out because his pacemaker was programmed in VVI mode at low rate, due to intolerance of DDD pacing. Among the other 4 patients no clinical and laboratory parameters were significantly different after 1 year of follow-up. In conclusion, DDD pacing in selected patients with dilated cardiomyopathy showed disappointing results, despite a strict and laboratory monitoring; DDD pacing could be of major benefit in larger populations, according to Doppler mitral flow pattern: those patients with a larger A-wave amplitude could be more sensitive to DDD pacing than those with evidence of poor atrial systole. Moreover, biatral and/or biventricular pacing could also play a significant role.