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Miriam Bortnik

Publications and source records attributed to Miriam Bortnik.

9 recordsLinked to original sources
PubMed2006

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.

Aged↗
PubMed2006

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.

Aged↗
PubMed2006

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.

Aged, 80 and over↗
PubMed2006

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.

Aged↗
PubMed2006

[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.

Aged↗
PubMed2005

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.

Cardiac Pacing, Artificial↗
PubMed2004

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.

Adult↗
PubMed2004

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.

Atrial Fibrillation↗