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Biomedical subjects

Z Blanck

Publications and source records attributed to Z Blanck.

At least 19 recordsLinked to original sources
PubMed2001

Electroanatomically guided catheter ablation of ventricular tachycardias causing multiple defibrillator shocks.

With conventional techniques, RF catheter ablation is difficult in patients with unstable VT or with multiple VTs. The feasibility of RF catheter ablation guided by three-dimensional electroanatomic mapping technique in patients whose implanted ICD continued to deliver multiple shocks due to VT despite use of antiarrhythmic medications was assessed in 19 patients (15 men, 4 women; mean age [+/- SD] 70+/-7 years). All had a prior history of MI and subsequently had received an ICD due to VT. During the 12-week preablation period, these patients received 31+/-15 shocks (range 4-62 shocks) due to refractory monomorphic VTs. An electroanatomic mapping technique using the CARTO system was performed to delineate scar tissue. RF catheter ablation was then performed at appropriate sites identified by pace mapping and by substrate mapping. Seventeen patients were on amiodarone at the time of ablation. Twenty-seven VTs were documented clinically, and 45 were induced during electrophysiological evaluation. Of the 45 tachycardias induced, 38 VTs were targeted for ablation. Catheter ablation was performed during sinus rhythm in 31 episodes and during VT in 7 episodes. During a mean follow-up of 26+/-8 weeks (range 18-48 weeks), 13 (66%) patients had no recurrence of VT (P < 0.0001) and antiarrhythmic drugs were discontinued or the number of medications reduced in 17 patients (P < 0.0001). Electroanatomic mapping is helpful in identifying sites for catheter ablation in highly symptomatic patients with refractory VT associated with myocardial scarring.

Aged↗
PubMed2000

Electroanatomic mapping to identify breakthrough sites in recurrent typical human flutter.

The accuracy of conventional techniques in localizing previous radiofrequency (RF) ablation sites and thus breakthrough sites of recurrent atrial flutter is somewhat limited. We investigated the role of electroanatomic mapping for identifying breakthrough sites or "gaps" at the tricuspid annulus and inferior vena cava (IVC)/eustachian ridge isthmus to help RF ablation in patients with recurrent typical flutter. Twelve patients (8 men, 4 women, age 63 +/- 10 years) with recurrent typical atrial flutter were included in the study. An electroanatomic mapping system (CARTO) was used to create a voltage map and activation and propagation patterns in the right atrium. Detailed voltage, activation, and propagation mapping of the tricuspid annulus and IVC/eustachian ridge isthmus allowed precise identification of gaps in all 12 patients at the tricuspid annulus (eight sites), IVC ridges (two sites), mid-isthmus region (one site), and tricuspid annulus and IVC ridges (one site). Radiofrequency energy directed at these sites eliminated atrial flutter in all 12 patients, confirmed by noninducibility of atrial flutter and demonstration of conduction block during atrial pacing on either side of the lesion lines. During a mean follow-up of 14.8 +/- 3.5 months (range 8-19 months), paroxysmal atrial flutter recurred in only one patient and was subsequently treated with amiodarone, although this had been ineffective prior to ablation. Electroanatomic mapping can precisely identify gaps in the lesion line responsible for breakthrough of recurrent typical atrial flutter at the tricuspid annulus and at the IVC/eustachian ridge isthmus. These sites can be targeted with RF ablation with a high degree of success.

Atrial Flutter↗
PubMed1999

Sudden cardiac death.

SCD continues to be an important cause of death and morbidity. Despite expanding insight into the mechanisms causing SCD, the population at high risk is not being effectively identified. Although there is still much to do in the management phase of SCD (predicting the efficacy of various therapies), recent clinical trials have helped define the relative risks and benefits of therapies in preventing SCD. Trials are underway to determine whether treating other patient populations, including asymptomatic patients after MI, will improve survival rate. The approach to reducing mortality rate will always be multifaceted; primary prevention of coronary artery disease and prompt salvage of jeopardized myocardium are 2 important aspects of this approach. In addition to interventions for MI, such as myocardial revascularization when indicated, simple and easily administered therapies that are likely to remain the most effective prophylactic interventions are aspirin, ACE inhibitors, beta-blockers, and cholesterol-lowering agents. However, the MADIT and AVID data clearly demonstrate a role for ICD therapy in a subgroup of patients who have VT/VF and are at risk of cardiac arrest. Even though the absolute magnitude of benefit associated with ICDs is still to be determined, the AVID study and other recent reports provide convincing evidence that patients who have VT/VF fare better with ICDs than with antiarrhythmic drug therapy. For the high-risk population described in this article, in addition to aggressive anti-ischemic and heart failure therapy, ICDs are now a mainstay of life-saving treatment. Still to be surmounted is the challenge of identifying patients who have nonischemic substrates and of providing them with the appropriate therapy. Guided by genetic studies and new insight into the mechanisms of such problems as congenital long QT syndrome, life-saving and life-enhancing therapies may soon be available for the management of SCD.

Adrenergic beta-Antagonists↗
PubMed1999

Ventricular arrhythmias, electrophysiologic studies, and devices.

Because of the high incidence of heart disease in the elderly, ventricular tachyarrhythmias are not infrequent. Determining the nature and extent of the underlying heart disease and identifying precipitating causes is required prior to instituting long-term therapy. Recent studies suggest that for hemodynamically unstable ventricular tachyarrhythmias, mortality is lower with the implantable cardioverter-defibrillator compared with pharmacologic therapy. This benefit is likely to be more modest in the elderly because of competing cardiac and noncardiac causes of death. For similar reasons, the favorable results reported with the prophylactic use of the implantable cardioverter-defibrillator are likely to be attenuated in the elderly.

Aged↗
PubMed1999

Reversing the initial phase polarity in biphasic shocks: is the polarity benefit reproducible?

The effect of initial phase polarity (IPP) reversal using biphasic shocks on DFT at the time of implantation of implantable cardioverter defibrillator and the reproducibility of this effect during predischarge testing was evaluated in a randomized fashion. Twenty-two patients with ventricular tachycardia or ventricular fibrillation (VF) who received either the Medtronic 7219D (7 patients), 7219C (12 patients), 7223 (1 patient), or CPI Ventak MINI (2 patients) were studied. The DFT was determined in a randomized fashion at implantation and during predischarge testing using a binary search protocol. Initial shock was delivered at 12 J. If successful, subsequent shock was delivered at 6 J, following which the shock was incremented or decremented by 3 J depending upon the success. The DFT for right ventricular (RV)- and RV + IPP was 10.9 +/- 4.1 J and 11.1 +/- 4.0 J, respectively, at implant (P = ns) and 9.7 +/- 4.3 J and 8.4 +/- 6 J, respectively, (P = ns) at predischarge testing. Of the six patients who had better DFT with RV + at implantation, only one patient maintained the benefit during predischarge testing. The differences observed in IPP in individual patients may not be demonstrable during repeated testing. These findings may have implications on how these devices should be programmed.

Adult↗
PubMed1999

Driving safety among patients with neurocardiogenic (vasovagal) syncope.

Neurocardiogenic syncope is one of the most common causes of syncope. However, the important issue of driving related injury due to syncope in this population is not well defined. Risk of injury due to syncope while driving and driving behavior was evaluated in 155 consecutive patients (92 women and 63 men; mean age 49 +/- 19 years) with history of syncope in whom hypotension and syncope or presyncope could be provoked during head-up tilt testing. Patients with syncope and positive head-up tilt table test were treated with pharmacological therapy. All participants were asked to fill out a detailed questionnaire regarding any driving related injuries and their driving behavior before tilt table testing and during follow-up. Prior to head-up tilt testing two patients had syncope while driving, and one of these patients had syncope related injury during driving. The mean duration of syncopal episodes was 50 +/- 14 months (range 12-72 months). Of the 155 patients, 52 (34%) had no warning prior to syncope, while 103 (6%) had warning symptoms such as dizziness prior to their clinical syncope. Following a diagnosis of neurocardiogenic syncope established by head-up tilt testing, six patients stopped driving on their own. During a median follow-up of 22 months recurrent syncope occurred in five (3.2%) patients. No patient had syncope or injury during driving. In conclusion, syncope and injury while driving in patients with neurocardiogenic syncope is rare. The precise mechanism of this is unclear but may be related to posture during driving. Consensus among the medical community will be needed to provide specific guidelines in these patients.

Accidents, Traffic↗
PubMed1999

Electroanatomic mapping for radiofrequency ablation of cardiac arrhythmias.

Radiofrequency catheter ablation is the current treatment of choice for several cardiac arrhythmias. The conventional approach utilizing intracardiac electrograms during sinus rhythm and during tachycardia has inherent limitations including limited two-dimensional fluoroscopic imaging and the ability to evaluate several potential sites for ablation and to go precisely to the most suitable site. Recently, a nonfluoroscopic three-dimensional electroanatomic system has been developed for mapping arrhythmias. We describe in this report the advantage of utilizing the system in facilitating a successful outcome in three patients with different arrhythmias.

Adult↗
PubMed1999

Ventricular arrhythmias, electrophysiologic studies, and devices

Because of the high incidence of heart disease in the elderly, ventricular tachyarrhythmias are not infrequent. Determining the nature and extent of the underlying heart disease and identifying precipitating causes is required prior to instituting long-term therapy. Recent studies suggest that for hemodynamically unstable ventricular tachyarrhythmias, mortality is lower with the implantable cardioverter-defibrillator compared with pharmacologic therapy. This benefit is likely to be more modest in the elderly because of competing cardiac and noncardiac causes of death. For similar reasons, the favorable results reported with the prophylactic use of the implantable cardioverter-defibrillator are likely to be attenuated in the elderly.

Journal Article↗
PubMed1998

Spontaneous reinitiation of atrial fibrillation following transvenous atrial defibrillation.

Spontaneous reinitiation of atrial fibrillation (AF) has not been systematically looked at in patients undergoing transvenous AF. This study involved 11 patients, the mean age 60 +/- 8 years, 3 male and 8 female, in whom transvenous atrial defibrillation successfully converted AF to sinus rhythm. Eight patients had paroxysmal AF and three patients had chronic persistent AF for 4 weeks or more. Four patients were taking antiarrhythmic medications at the time of testing. Multipolar transvenous catheters were positioned inside the coronary sinus, right atrium, and the right ventricle. Atrial defibrillation testing was performed using the METRIX atrial defibrillation system in nine patients and the Ventritex HVSO2 in the remaining two patients. A total of 64 therapeutic shocks (range 3-11) were delivered in the 11 patients, and 31 of these successfully converted AF to sinus rhythm. In four patients spontaneous AF was reinitiated following 12 successful transvenous atrial defibrillation episodes. The mean time to reinitiation of AF following shock delivery and restoration of sinus rhythm was 8.26 +/- 5.25 seconds, range 1.8-19.9 seconds. All 12 episodes of spontaneous AF were preceded by a spontaneous premature atrial complex. The coupling interval of the premature atrial complexes was 443 +/- 43 ms, range 390-510 ms. None of the patients taking antiarrhythmic medications or those demonstrating no premature atrial complexes had spontaneous reinitiation of AF. In conclusion, spontaneous reinitiation of AF can occur in a significant proportion of patients with AF undergoing transvenous atrial defibrillation. This phenomenon is preceded by the occurrence of atrial premature complex. Findings of this study may have significant clinical implications.

Adult↗
PubMed1998

Optimization of shocking lead configuration for transvenous atrial defibrillation.

INTRODUCTION: High atrial defibrillation energy requirements (ADER) in patients with chronic atrial fibrillation (AF) may limit the acceptance of transvenous atrial defibrillation. We evaluated an optimized defibrillation electrode configuration that could help to reduce the ADER in patients with AF. METHODS AND RESULTS: We tested ten different configurations in nine dogs with AF (3.33+/-2.92 days) induced by rapid atrial pacing. The configurations were: right atrial (RA) appendage as anode and coronary sinus (CS) as cathode; RA and innominate vein (I) as anode to CS (cathode); RA-CS (anode) to I (cathode); I-CS (anode) to RA (cathode); RA and left lateral subcutaneous patch (P) as anode to CS (cathode); RA-CS (anode) to P (cathode); P-CS (anode) to RA (cathode); superior vena cava (SVC) and CS (anode) to RA (cathode); RA-CS (anode) to SVC (cathode); and RA-SVC (anode) to CS (cathode). ADER was defined as the voltage needed to defibrillate the atria in 10% to 90% of 20 consecutive shocks. Three lead systems had ADER lower than the RA (anode) to CS (cathode) configuration, which required a mean of 143+/-58 volts. These three were: RA-SVC (anode) to CS (cathode) 103+/-29 V; I-CS (anode) to RA (cathode) 129+/-39 V; and P-CS (anode) to RA (cathode) 130+/-38 V. The remaining configurations had ADER higher than the RA (anode) to CS (cathode) configuration. CONCLUSION: Adding an additional shocking electrode may reduce ADER when compared with the RA (anode) to CS (cathode) configuration. This concept could be incorporated into future implantable atrial defibrillators or used for refractory patients undergoing temporary transvenous cardioversion.

Animals↗
PubMed1998

Sinus tachycardia with atrioventricular block: an unusual presentation during neurocardiogenic (vasovagal) syncope.

INTRODUCTION: Neurocardiogenic (vasovagal) syncope is characterized by hypotension and bradycardia. The presence of sinus tachycardia along with AV block during syncope in patients with neurocardiogenic syncope has not been described previously. METHODS AND RESULTS: Two female patients (18 and 16 years old) with recurrent syncope and documented sinus tachycardia at the time of syncope are described. Patient 1 had recurrent episodes of syncope. During one of these episodes, which occurred while she was being monitored, sinus tachycardia along with high-grade AV block was seen at the time of syncope and hypotension. Patient 2 had a history of recurrent syncope and seizure. During one of these episodes, she was documented to have ventricular asystole lasting for about 39 seconds. The sinus rate was 480 msec at the beginning, before slowing down to 960 msec prior to restoration of sinus rhythm with 1:1 AV conduction. The same scenario was repeated during head-up tilt testing. Both patients were treated successfully with oral disopyramide and, during a follow-up of 28 months and 9 months, have remained symptom-free. CONCLUSION: Sinus acceleration along with high-grade AV block during syncope and hypotension can occur in some patients with neurocardiogenic syncope. The exact mechanism of this phenomenon is unclear.

Adolescent↗
PubMed1998

Catheter ablation of atrial flutter using radiofrequency current: cumulative experience in 61 patients.

UNLABELLED: We present our experience with radiofrequency catheter ablation of common atrial flutter. METHODS: Radiofrequency ablation of atrial flutter was performed utilizing percutaneous techniques and the anatomic approach under conscious sedation or general anesthesia. RESULTS: Sixty-one consecutive patients (51 men, and 10 women) aged 59 +/- 12 years with medically refractory atrial flutter underwent catheter ablation. Thirty-eight patients (62%) had structural heart disease, including complex congenital anomalies in one patient. Atrial flutter ablation was successfully accomplished in 55 patients (90%) in one session. There were no complications, and all patients were discharged within 24-hours of the procedure. During a mean follow-up of 10 +/- 9 months, recurrent atrial flutter occurred in 11 patients (18%), eight of which successfully underwent repeat atrial flutter ablation. CONCLUSIONS: Catheter ablation of atrial flutter using radiofrequency current is safe and has a high success rate. This nonpharmacologic approach should be considered as the first line of therapy for common atrial flutter prior to the institution of antiarrhythmic drugs.

Adolescent↗
PubMed1998

Atrioventricular nodal modification and atrioventricular junctional ablation for control of ventricular rate in atrial fibrillation.

Atrial fibrillation results in several structural and functional changes in the heart that lead to worsening ventricular function. Although restoration of sinus rhythm is the ideal goal, it is not always feasible. Pharmacologic therapy is associated with adverse effects and is not always effective. We have reviewed the current status of nonpharmacologic therapy in the management of rapid ventricular response due to atrial fibrillation. Electrophysiologic studies have confirmed that the posterior inputs to the AV node have a shorter refractory period and are mainly responsible for maintaining rapid ventricular response in atrial fibrillation. AV nodal modification involves ablation of these posterior inputs in a sequential fashion until a significant reduction of ventricular response is achieved. This procedure has been reported to be successful in maintaining the controlled ventricular response in about 70% of the patients over long-term follow-up. Ablation of the AV node with implantation of a permanent pacemaker is a more definitive procedure and simpler to perform. Reduction in ventricular response achieved with this procedure results in improvement of the patient's clinical symptoms as well as the underlying left ventricular function. Nonpharmacologic therapy for control of ventricular rate should be considered for patients with atrial fibrillation, in whom pharmacologic therapy for rate control is ineffective or poorly tolerated.

Atrial Fibrillation↗
PubMed1998

Implantable atrial defibrillator for atrial fibrillation.

Atrial fibrillation is a common problem. Pharmacological and nonpharmacological approaches have limited therapeutic efficacy in many patients. Low energy transvenous atrial defibrillation using catheters positioned inside the right atrium and cornonary sinus has been shown to be efficacious in converting atrial fibrillation to sinus rhythm. We report the successful use of this technology in an implantable form in a patient with symptomatic atrial fibrillation. The patient could be kept in sinus rhythm using an implanted atrial defibrillator.

Atrial Fibrillation↗
PubMed1997

Ventricular tachycardia in valvular heart disease: facilitation of sustained bundle-branch reentry by valve surgery.

BACKGROUND: The clinical characteristics of sustained monomorphic ventricular tachycardia (SMVT), when it develops after valve surgery, have not been described. METHODS AND RESULTS: Between 1985 and 1996, 31 patients (30 men and 1 woman) who had undergone valve surgery were found to have inducible SMVT. Nine patients (29%) had sustained VT due to bundle-branch reentry (BBR) (group 1). Four of these patients had normal left ventricular function, and VT with a right bundle-branch morphology was inducible in 4 patients. Group 2 included 20 patients with inducible myocardial (ie, non-BBR) VT. Coronary artery disease was present in 15 group 2 patients (75%) due to atherosclerotic (n=12) and nonatherosclerotic (n=3) causes. Two patients had both inducible sustained BBR and myocardial VT (group 3). Sustained BBR VT occurred significantly earlier after valve surgery (median, 10 days) than the onset of postoperative myocardial VT (median, 72 months; P<.005). CONCLUSIONS: Myocardial VT was the most common type of inducible SMVT in patients with valvular heart disease. The majority of these patients had underlying coronary artery disease and significant left ventricular dysfunction. However, in almost one third of the patients, sustained BBR VT was the only type of inducible SMVT. This type of VT was facilitated by the valve procedure occurring within 4 weeks after surgery in most patients. In these patients, left ventricular function was relatively well preserved, and the right bundle-branch block type of BBR was frequently induced. Because a curative therapy can be offered to these patients (ie, bundle-branch ablation), BBR should be seriously considered as the mechanism of VT in patients with valvular heart disease, particularly if the arrhythmia occurs soon after valve surgery.

Adult↗
PubMed1997

Comparison of outcome of implantable cardioverter defibrillator implantation in patients with severe versus moderately severe left ventricular dysfunction secondary to atherosclerotic coronary artery disease.

This study was undertaken to assess the feasibility and clinical outcome of implantable cardioverter-defibrillators (ICDs) among patients with coronary artery disease and left ventricular ejection fraction (LVEF) of <20%. The morbidity, mortality, and the long-term survival of 117 patients with LVEF of <20% (group 1) were compared with 321 patients with LVEF of 20% to 40% (group 2). Mortality in the first 30 days after ICD implantation was 0% for group 1 and 0.6% in group 2. Actuarial survival (all cause) at the end of 2, 4, and 5 years were 83%, 70%, and 62%, respectively, in group 1 and 90%, 80%, and 71% in group 2 (p = 0.05). Fifty-five patients (47%) in group 1 and 126 patients (39%) in group 2 received appropriate shocks during follow up. Among the patients in group 1, the overall survival at 2 years after an appropriate shock from an ICD was 92% for patients <60 years of age, 77% for patients ages 60 to 69, and 53% for patients >70 years old. Although the overall survival of patients in group 1 was slightly lower compared with those in group 2, in a multivariate analysis, the EF was not an independent predictor of poor survival. The ICD can be implanted with acceptable operative morbidity and mortality in selected patients with LVEF of <20%.

Aged↗
PubMed1997

Efficacy of the implantable cardioverter-defibrillator in the elderly.

OBJECTIVES: We sought to assess the effect of advanced age on the outcome of patients with an implantable cardioverter-defibrillator (ICD). BACKGROUND: ICDs are effective in preventing sudden cardiac death in susceptible patients, but their beneficial effect on survival is attenuated by the high rate of nonsudden cardiac death in those treated. Although advanced age is an important variable in determining cardiovascular mortality, its impact on the outcome of patients with an ICD has been inadequately studied. METHODS: We performed multivariate analysis of a data base consisting of 769 consecutive patients with an ICD. Seventy-four patients > or = 75 years old at ICD implantation (Group 1) were compared with the remaining 695 patients (Group 2). RESULTS: The two groups were similar in clinical presentation, left ventricular function and gender distribution. The mean follow-up time was 29 and 42 months, respectively, for patients in Group 1 and Group 2. Actuarial survival at 4 years was 57% in Group 1 versus 78% in Group 2 (p = 0.0001). This difference was primarily due to a higher rate of nonsudden cardiac death in Group 1. On multivariate analysis, age > or = 75 years, New York Heart Association functional class III, left ventricular ejection fraction < 30% and appropriate shocks during follow-up were independently associated with increased mortality (odds ratio 3.56, 1.8, 1.6 and 1.39, respectively). CONCLUSIONS: Among patients with similar functional class and ejection fraction, the mortality risk is increased threefold in those > or = 75 years old at the time of ICD implantation. Extrapolation of results from younger patients is likely to overestimate ICD benefit in the elderly.

Age Factors↗