Intra-Atrial Reentrant Tachycardia After Palliation of Congenital Heart Disease:

Catheter Mapping of IART. introduction: The anatomic substrate of intra-atrial reentrant tachycardia (IART) following congenital heart surgery is poorly understood, but is presumed to be different than common atrial flutter. Methods and Results: To study the mechanisms of IART, we used a new technique for high-density endocardial mapping using recordings from a multipolar basket recording catheter (25 bipolar pairs). For each recording, biplane fluorographic reference points were digitized to obtain the spatial locations of electrode pairs, and activation times were calculated using temporal reference points from the surface ECG. Using custom software, data were combined to create three-dimensional atrial activation sequence maps, which were displayed as animated sequences. Using this technique, recordings were made in induced and/or spontaneous IART in 8 patients following congenital heart surgery (5 Fontan, 2 tetralogy of Fallot repair, 1 ventricular septal defect repair), and in 3 patients with normal intracardiac anatomy (I with type I atrial flutter). Ten discrete IART activation sequences were recorded; 2 patients had 2 sequences each. IART maps were constructed using a median of 108 electrode positions (range 27 to 197) from a median of 6 recordings/sequence (range 3 to 11). Sinus or paced atrial rhythms were also recorded, and maps were created in a similar fashion. Visual analysis of activation sequences of sinus and paced rhythm were anatomically concordant with known mechanisms of atrial activation. IART sequences revealed diverse mechanisms; only 1 IART circuit was similar to that associated with common atrial flutter. Activation wavefront emergence from presumed zones of slow conduction, lines of conduction block, and apparent bystander activation were observed. Conclusions: High-density atrial activation sequence maps demonstrate that IART following congenital heart surgery utilizes diverse circuits and is distinct from common atrial flutter. The technique used to create these three-dimensional activation sequences may improve understanding of these complex atrial arrhythmias and assist in the development of ablative therapies.     

Dose- and Time-Dependent Liquid Sclerosant Effects on Endothelial Cell Death

BACKGROUND: Intravenous sclerotherapy solutions can induce endothelial cell death. OBJECTIVE: The objective was to determine the relationship between sclerosant concentration and minimum contact time required for in endothelial cell death. METHODS: Cultured bovine aortic endothelial cells were exposed to a broad range of concentrations of two liquid sclerosants, polidocanol and sodium tetradecyl sulfate. Fluorescence microscopy was used to study cells using dyes specifically indicating changes in intracellular calcium levels, nitric oxide production, and loss of cell membrane integrity after sclerosant exposure. Fluorescence intensity measurements were used to identify the timing of cell death. RESULTS: Calcium signaling and nitric oxide pathways were activated by the administration of the sclerosants and were followed by cell death. The time to the activation and the cell death was dependent on the concentration of sclerosants. At 0.3% polidocanol or 0.1% sodium tetradecyl sulfate, cell death occurred within 15 minutes. At less than 0.003% polidocanol and at 0.005% sodium tetradecyl sulfate, cells remained alive after 60 minutes. CONCLUSION: Both sclerosants rapidly led to cell death at sufficiently high concentrations. At low sclerosant concentrations, cell viability was maintained beyond the recording time of the experiment. The timing of endothelial cell death is predictable based on sclerosant concentration during exposure.     

Left Ventricular Diastolic Function in Idiopathic Cardiomyopathy: Doppler Hemodynamic Correlations

The left ventricular diastolic filling pattern in congestive cardiomyopathy is heterogeneous and may vary from a "rapid filling predominant pattern" to an "atrial filling predominant pattern." The observed pattern of diastolic filling may depend on a complex interaction of factors including: left ventricular relaxation, left ventricular stiffness, external constraining forces, loading conditions, and heart rate. These factors appear to express themselves individually and collectively through alterations in the time course and extent of the transmitral pressure gradient. In this review, the physiological basis for each of these diastolic filling patterns is discussed based on previous clinical and experimental studies that either directly or indirectly address these issues. (ECHOCARDIOGRAPHY, Volume 8, March 1991)     

High Prevalence of False Chordae Tendinae in Patients Without Left Ventricular Tachycardia

Background: Left ventricular (LV) false chordae tendinae (false chords) have been implicated as a source of idiopathic left (IL) ventricular tachycardia (VT). However, it is unknown whether pretest bias contributes to an apparent association with disease. The purpose of this study was to determine the prevalence of false chords on direct inspection of the LV endocardium.
Methods: In a prospective series, 75 hearts were examined to identify and characterize false chords, including 20 specimens examined at autopsy and 55 consecutive patients undergoing mitral valve surgery. Medical records were reviewed for history of VT, including ILVT.
Results: Of 75 patients whose hearts were studied, none had a history of ILVT and only 5 had a history of any VT. False chords were present in 34 of 75 (45%) hearts, including 13 of 20 (65%) at postmortem and 21 of 55 (38%) examined at surgery (P = 0.07). The prevalence of false chords was not different among patients with (3 of 5 [60%]) versus those without (31 of 70 [44% p = 0.65]) a history of VT (P = 0.65).
Conclusions: In this prospective anatomic series, the prevalence of LV false chords on autopsy and surgical inspection was approximately 45% among patients without ILVT. Previously reported associations of false chords with ILVT likely underestimated the prevalence of false chords in a normal population.     

Analysis of the Effectiveness of In-Office and Transtelephonic Follow-Up in Terms of Pacemaker System Complications

A study was undertaken to determine the most effective method of pacemaker follow-up in terms of the total number of complications detected and yield per follow-up in single and dual chamber pacing systems. The analysis involved 9,786 patient records from 635 patients. The records were reviewed with respect to method of follow-up, number of chambers paced, and complications detected. Complications included: oversensing, undersensing, noncapture, pocket and diaphragmatic stimulation, pacemaker mediated tachycardia, crosstalk, pulse generator malfunction, lead malfunction, infection/erosion, premature end of service, exit block, and other miscellaneous problems. Eight thousand two hundred eighty-eight of the 9,786 follow-ups were performed in the office while 1,498 were transtelephonic. Single chamber pacing systems were implanted in 329 patients and 306 were dual chamber systems. A total of 599 complications were detected. Analysis yielded a per patient complication rate of 5.1 % (single chamber) and 8.4% (dual chamber) for in-office follow-up. This compared to a transtelephonic follow-up per patient complication rate of only 0.3% (single chamber) and 1.0% (dual chamber). In-office pacemaker follow-up is significantly more effective (P < 0.001) than transtelephonic follow-up in detecting both single and dual chamber pacemaker system complications.     

Clinical Experience with a New Multiprogrammable Dual Chamber Pacemaker

We evaluated the clinical performance of a new dual chamber pacemaker, ELA Chorus(tm), in 35 patients. This device incorporates linear rate adaptive AV delay (AVDR), rate smoothing, fallback, impedance telemetry, pacemaker mediated tachycardia (PMT) recognition and reprogramming software, intracardiac electrogram displays, aufothreshold testing, diagnostic data, battery depletion curves, and laptop computer programming. Mean patient age was 68 years; 18 patients had AV block, six had sinus node dysfunction (one with AV block), nine had carotid sinus hypersensitivity (three with AV block), and two had vagally mediated syncope. At hospital discharge, programming was DDD with a mean low rate of 60 (50–70) beats/min, mean high rate of 126 (120–154) beats/mm; AVDR was ON in 21 patients, rate smoothing ON in six patients, fallback ON in six patients, and PMT reprogramming algorithm ON in 27 patients, Pacemaker follow-up involved 500 clinic visits over 14.3 months (1–36). Three patients developed atrial fibrillation, reprogrammed to DDI mode (two patients) or fallback (one patient). Fallback was used 617 times. PMT occurred 427 times in six patients; the PMT algorithm reprogrammed AV delay and postventricular atrial refractory period (PVARPJ automatically, a function unique to the Chorus(tm). Intracardiac electrograms and autothreshold testing improved follow-up efficiency. This new dual chamber pacemaker enhances programming flexibility and improves diagnostic accuracy at follow-up.     

Variable Effects of Adenosine on Retrograde Conduction in Patients with Atrioventricular Nodal Reentry Tachycardia

Adenosine has been demonstrated to reliably produce transient block of atrioventricular nodal (AVN) conduction, and has been advocated as a method of differentiating retrograde conduction via the atrioventricular node from accessory pathway conduction. However, the response of retrograde AVN to adenosine in patients with typical atrioventricular nodal reentry tachycardia (AVNRT) remains unclear. We evaluated 13 patients (mean age 45 ± 20 years) with typical AVNRT prior to AVN modification. During right ventricular pacing, a rapid bolus of adenosine (0.2 mg/kg; maximum 18 mg) was administered. Adenosine sensitivity, defined by transient ventriculoatrial block, was observed in six patients, while in seven patients ventriculoatrial conduction was unaffected. An adenosine bolus administered during sinus rhythm or atrial pacing resulted in antegrade atrioventricular block in all the adenosine resistant patients in whom this was performed (n = 6). Comparisons of AVN electrophysiological characteristics between the adenosine sensitive and adenosine resistant patients were performed. There was no difference with respect to ventriculoatrial effective refractory period, ventriculoatrial Wenckebach, AVNRT cycle length, and His to atrial echo interval in AVNRT. However, there was a trend toward a longer antegrade fast pathway ERP in the adenosine sensitive group (P = 0.07). Electrophysiological properties do not predict retrograde AVN adenosine sensitivity. Adenosine does not cause retrograde AVN block in all patients with AVNRT, and therefore cannot reliably distinguish between retrograde conduction via the AVN or an accessory pathway.     

A Rare Case of Permanent Junctional Reciprocating Tachycardia Ablated on the Roof of the Left Atrium

A Rare Case of Permanent Junctional Reciprocating Tachycardia. Left‐sided anteroseptal accessory pathways that course through the aortomitral fibrous continuity are some of the rarest types of accessory pathways. At this region the atrium and ventricle are separated by their greatest distance because of the intervening aortic valve. These pathways often have a long circuitous course that may involve the root and cusps of the aortic valve. Prior reports have demonstrated the feasibility of ablating these pathways along the anteroseptal mitral annulus, the left ventricular outflow tract, or in the left or noncoronary cusps of the aortic valve. We describe a case of a concealed decremental anteroseptal accessory pathway that was ablated on the roof of the left atrium remote from the mitral or aortic valve annuli. This report indicates that when an appropriate site for ablation of a left‐sided anteroseptal accessory pathway is not found close to a valve annulus, these pathways may be amenable to ablation by targeting their atrial insertion site. (J Cardiovasc Electrophysiol, Vol. 24, pp. 464‐467, April 2013)     

A Self-Contained Method of Evaluating the Provision of Preventive Care in General Practice

In an earlier paper a method was described by which generalpractitioners are able to obtain dissatisfaction data from theirpatients by means of questionnaires. A similar approach hasbeen used to study preventive care activities of general practitioners.We have found it to be practicable and acceptable to patientsand surgery personnel. It also yields results which are consistentand which have apparently stimulated some practitioners to altertheir practice behaviour by increasing their preventive careactivities.