Browsing by Author "Valaparambil, Ajitkumar"

Now showing 1 - 3 of 3
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    An unusual mechanism of sustained right atrial tachycardia.
    (Indian pacing and electrophysiology journal, 2011)
    Lower loop re-entry (LLR) flutter is a rare type of atypical right atrial flutter. Most of the reported cases occurred in association with typical flutter patterns as a transient arrhythmia. Our case is unique in the fact the LLR was sustained and persisted independently.
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    Doppler echocardiographic assessment of TTK Chitra prosthetic heart valve in the mitral position
    (EUROPEAN JOURNAL OF ECHOCARDIOGRAPHY, 2008)
    Aims TTK Chitra heart valve prosthesis (CHVP), a tilting disc mechanical heart valve of tow cost and proven efficacy, has been in use for the last 15 years. Although various studies substantiating its long-term safety and efficacy are available, no study had assessed its echocardiographic characteristics. The purpose of this study was to determine the normal Doppler parameters of CHVP in the mitrat position and to assess whether derivation of mitrat valve area (MVA) using the continuity equation (CE) and more commonly used pressure half-time (PHT) method is comparable in the functional assessment of this tilting disc mitral prosthesis.Methods and results Doppler echocardiography was performed in 40 consecutive patients with CHVP in the mitrat position. All patients were clinically stable, without evidence of prosthetic valve dysfunction such as significant obstruction or regurgitation, enclocarditis, left ventricular dysfunction (ejection fraction <40%), or significant aortic regurgitation. Valve sizes studied included 25, 27, and 29 mm. Mitrat valve area was derived both by the PHT method and by the CE, using the stroke volume measured in the ventricular outflow tract divided by the time-velocity integral of CHVP jet. The peak Doppler gradient ranged from 5 to 21 (mean 11.0) mmHg, and the mean gradient ranged from 1.7 to 9.2 (mean 4.1) mmHg. Mean gradient negatively correlated with an increase in the actual orifice area (ACA) derived from the valve orifice diameter given by the manufacturer (r = -0.45, P = 0.004). Mitral valve area calculated by both PHT and CE increased significantly with an increase in the ADA (r = 0.42, P = 0.007 and r = 0.32, P = 0.046, respectively). Mitrat valve area by the CE averaged 1.55 +/- 0.36 cm(2) (range 0.85 cm(2) for a 25 mm valve to 2.41 cm(2) for a 29 mm valve) and was smaller than by PHT (mean 2.04 +/- 0.41 cm(2), range 1.40-3.14 cm(2); P = 0.0001; t-test), irrespective of whether PHT is less than or >110 ms.Conclusion The Doppler parameters obtained with CHVP in the mitrat position are comparable with those obtained with the different prosthetic valves in common use. In the selected group of patients with CHVP, assessment of MVA by the PHT method is comparable with that by the CE. Areas by both methods were smaller than the AOA provided by the manufacturer, as seen in other similar design valves.
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    Electrophysiology study and radiofrequency catheter ablation of atriofascicular tracts with decremental properties (Mahaim fibre) at the tricuspid annulus
    (EUROPACE, 2008)
    Aims The aim was to study the common mapping methods for Mahaim fibre and their role in radiofrequency ( RF) ablation.Methods and results Fifteen patients having Mahaim fibre tachycardia underwent electrophysiological study. Mahaim fibre mapping methods like (i) Mahaim potential ( M), (ii) shortest atrial stimulus-to-preexcitation (STP), and (iii) mechanical trauma induced loss of conduction were studied. Accessory pathway mapping was performed by M potential in 10 patients (67%), shortest atrial STP in 3 patients (20%), and mechanical trauma in 2 patients (13%). Mahaim fibre was localized at right atrial freewall of tricuspid annulus (8-10 o'clock) in 13 patients (87%), at 6.30 o'clock in one patient, and at 5 o'clock in 1 patient. Fourteen patients underwent RF ablation. Thirteen patients had complete loss of conduction over accessory pathway and one had partial modi. cation with a conduction delay. Radiofrequency ablation was not performed in one patient ( shortest STP group) due to its closeness to the compact atrioventricular node. Mahaim junctional acceleration during RF ablation was observed in all patients of M potential, 1 patient of mechanical trauma, and none of the atrial STP group. One patient ( M potential group) had tachycardia recurrence during follow-up.Conclusion Mahaim fibre is commonly located between 8 and 10 o'clock at tricuspid annulus. M potential guides to successful RF ablation in most patients. Mahaim junctional acceleration is commonly seen during RF ablation guided by M potential map.