Biomedical subjects

Prashanthan Sanders

Publications and source records attributed to Prashanthan Sanders.

80 records · Page 5Linked to original sources

PubMed2003

Phased-array intracardiac echocardiography for defining cavotricuspid isthmus anatomy during radiofrequency ablation of typical atrial flutter.

INTRODUCTION: Cavotricuspid isthmus (CTI) topography includes ridges, pouches, recesses, and trabeculations. These features may limit the success of radiofrequency ablation (RFA) of typical atrial flutter (AFL). The aim of this study was to assess the utility of phased-array intracardiac echocardiography (ICE) for imaging the CTI and monitoring RFA of AFL. METHODS AND RESULTS: Fifteen patients (mean age 64 +/- 9 years) underwent ICE assessment (imaging frequency 7.5-10 MHz) before and after RFA of AFL. The ICE catheter was positioned at the inferior vena cava-right atrial junction and the following parameters were measured: (1) CTI length from the tricuspid valve to the eustachian ridge; (2) extent of CTI pouching; and (3) thickness pre/post RFA of the anterior, mid, and posterior CTI. CTI length was 35 +/- 6 mm at end-ventricular systole but shorter (30 +/- 6 mm) and more pouched at end-ventricular diastole (P = 0.02). A pouch or recess was seen in 11 of 15 patients (mean depth 6 +/- 2 mm). The septal CTI was more pouched than the lateral CTI, but the latter had more prominent trabeculations. Trabeculations were seen in 10 of 15 patients, and at these locations the CTI was 4.6 +/- 1 mm thick. Anterior, mid, and posterior CTI thickness pre-RFA was 4.1 +/- 0.8, 3.3 +/- 0.5, and 2.7 +/- 0.9 mm, respectively (P < 0.001 by analysis of variance). ICE guided RFA away from unfavorable CTI features (recesses/thick trabeculations). RFA applications created discrete CTI lesions that coalesced, forming diffuse CTI swelling. Post-RFA thickness was as follows: anterior 4.8 +/- 0.8 mm (P = NS vs pre); mid 3.8 +/- 0.8 mm (P = 0.05 vs pre); and posterior 3.8 +/- 0.8 mm (P = 0.02 vs pre). CONCLUSION: Phased-array ICE permits novel real-time CTI imaging with excellent endocardial resolution and may facilitate RFA of AFL.

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PubMed2003

Accessory pathway in left inferoposterior diverticulum masquerading as left posterior pathway due to conduction over coronary sinus to left atrium connection.

We report the case of an accessory pathway in a left inferoposterior diverticulum. The pathway masqueraded as a true left lateral pathway due to the direction of activation over a coronary sinus to left atrium connection. The patient had undergone four prior failed ablation attempts at other institutions using both a transseptal and retrograde approach.

Adult↗

PubMed2002

Usefulness of phased-array intracardiac echocardiography for the assessment of left atrial mechanical "stunning" in atrial flutter and comparison with multiplane transesophageal echocardiography(*).

We compared transesophageal and phased-array intracardiac echocardiography (TEE/ICE) for the 2-dimensional and spectral Doppler assessment of left atrial (LA) mechanical function. TEE is commonly used to assess LA body and LA appendage mechanical function in patients who are undergoing radiofrequency ablation of typical atrial flutter. Fifteen patients underwent TEE and ICE imaging before and after ablation of typical atrial flutter. The following parameters were measured: (1) LA appendage emptying velocity and fractional area change, (2) severity of LA spontaneous echo contrast (graded 0 to 4), (3) maximal inflow velocity of the left and right upper pulmonary veins, and (5) maximal mitral valve E- and A-wave inflow velocities in sinus rhythm. Diagnostic quality imaging was achieved in all patients with TEE and ICE. Comparing TEE and ICE, the following absolute values and linear correlation coefficient (R) were obtained: preablation LA appendage emptying velocity: 0.45 +/- 0.21 versus 0.44 +/- 0.21 m/s (r = 0.95, p = <0.001); postablation LA appendage velocity: 0.33 +/- 0.24 versus 0.34 +/- 0.24 m/s (r = 0.97, p <0.001); LA appendage fractional area change: 35.3 +/- 13.7 versus 35.9 +/- 17.1% (r = 0.81, p <0.001); left upper/right upper pulmonary vein inflow velocity: 0.50 +/- 0.17/0.49 +/- 0.18 versus 0.51 +/- 0.17/0.47 +/- 0.20 m/s (r = 0.93/0.90, p <0.001); mitral valve E/A wave: 0.66 +/- 0.14/0.31 +/- 0.14 versus 0.69 +/- 0.17/0.35 +/- 0.23 (r = 0.84/0.97, p <0.002); LA spontaneous echo contrast (pre- and postablation): 1.1 +/- 1.2/1.3 +/- 1.2 versus 1.2 +/- 1.3/1.4 +/- 1.3 (r = 0.92/0.90, p <0.001). No patients were identified with LA appendage thrombus. Thus, TEE and phased-array ICE provided equivalent imaging data with high statistical correlation. ICE may be an imaging alternative to TEE in the evaluation of a "stunned" left atrium.

Adult↗

PubMed2002

Reversal of atrial mechanical stunning after cardioversion of atrial arrhythmias: implications for the mechanisms of tachycardia-mediated atrial cardiomyopathy.

BACKGROUND: Atrial mechanical stunning develops on termination of chronic atrial arrhythmias and is implicated in the genesis of thromboembolic complications after cardioversion. The mechanisms responsible for atrial mechanical stunning are unknown. The effects of atrial rate, isoproterenol, and calcium on atrial mechanical function in patients with atrial stunning have not been evaluated, and it is not known if atrial stunning can be reversed. METHODS AND RESULTS: Thirty-five patients with chronic atrial flutter (AFL) undergoing radiofrequency ablation were studied. Fifteen patients in sinus rhythm undergoing ablation for paroxysmal AFL were studied as control for effects of the procedure. Left atrial appendage emptying velocities (LAAEVs) and spontaneous echocardiographic contrast (LASEC) were assessed by transesophageal echocardiography during AFL, after reversion to sinus rhythm, during atrial pacing at cycle lengths of 750 to 250 ms, after a postpacing pause, and with isoproterenol or calcium. With termination of AFL, LAAEV decreased from 59.0+/-3.7 cm/s to 18.8+/-1.4 cm/s (P<0.0001) and LASEC grade increased from 0.9+/-0.1 to 2.2+/-0.2 (P<0.0001). Pacing increased LAAEV to a maximum of 38.4+/-3.2 cm/s (P<0.0001) and reduced LASEC grade to 1.9+/-0.2 (P=0.005). Isoproterenol and calcium reversed atrial mechanical stunning with LAAEV increasing to 89.3+/-12.6 cm/s (P=0.0007) and 50.2+/-10.5 cm/s (P=0.005), respectively, and LASEC grade decreasing to 0.2+/-0.1 (P=0.001) and 1.4+/-0.2 (P=0.01), respectively. The postpacing pause increased LAAEV to 69.3+/-3.7 cm/s (P<0.0001). No change in LAAEV was observed in the paroxysmal AFL group. CONCLUSION: Atrial mechanical stunning can be reversed by pacing at increased rates and through the administration of isoproterenol or calcium. These findings suggest a functional contractile apparatus in the mechanically remodeled atrium as a result of chronic atrial flutter.

Atrial Flutter↗

PubMed2002

Sensitivity and specificity of concealed entrainment for the identification of a critical isthmus in the atrium: relationship to rate, anatomic location and antidromic penetration.

OBJECTIVES: This study was designed to determine the sensitivity and specificity of concealed entrainment (CE) for the identification of a critical isthmus in the atrium. BACKGROUND: Isthmus identification during entrainment mapping of macro-reentrant atrial tachycardia (MRAT) relies on the demonstration of CE. METHODS: Using the model of typical atrial flutter, entrainment was performed in 10 patients at four rates (flutter cycle length [FCL] minus 10/20/30/40 ms) from seven sites: isthmus entrance/exit, low lateral/high lateral/high septal right atrium and proximal/distal coronary sinus. Surface 12-lead electrocardiogram fusion was evaluated by three observers blind to patient status. The extent of antidromic penetration (AP) was measured off the pacing catheter positioned around the tricuspid annulus. RESULTS: The sensitivity for CE identifying any isthmus site was greatest at FCL-10 (100%), but the specificity was poor (54%). Conversely, specificity was greatest at FCL-40 (98%), but the sensitivity was poor (65%), with manifest entrainment (ME) observed from the isthmus entrance in 70% of episodes. At FCL-30, sensitivity (85%) and specificity (90%) were "balanced," but CE still resulted during entrainment from a non-isthmus site in five of 10 patients. Antidromic penetration increased with pacing CL shortening (p < 0.001) and correlated with the development of ME (p < 0.001). Antidromic penetration was significantly blunted from the isthmus exit compared to all other sites (p = 0.003). CONCLUSIONS: The sensitivity and specificity of CE for identifying an isthmus in the atrium are critically dependent on the pacing rate and the precise anatomic pacing site within the isthmus. These findings may have implications for the use of entrainment in the mapping of unknown MRAT circuits.

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PubMed2002

The challenge of endocardial right ventricular pacing in patients with a tricuspid annuloplasty ring and severe tricuspid regurgitation.

On occasion, patients with a tricuspid annuloplasty ring may require permanent cardiac pacing. Although it is technically possible to pass a ventricular transvenous lead through a tricuspid valve with an annuloplasty ring, the procedure is complicated by considerable chamber enlargement and mechanical distortion of the tricuspid valve often with severe residual tricuspid regurgitation. Over a 25-month period, transvenous ventricular lead placement following insertion of a tricuspid annuloplasty ring was successfully performed in five patients (three women). The patient mean age was 66 years (range 55-77 years). Four cases had slow atrial fibrillation and another paroxysmal atrial fibrillation requiring His-bundle ablation. Two patients had mitral valve replacement and two aortic and mitral valve replacements. All patients had residual severe to torrential tricuspid regurgitation. Seven ventricular steroid-eluting screw-in leads were used. Single leads were used in three cases, whereas in two others, two ventricular leads were attached to a dual chamber pulse generator. Although technically difficult, ventricular lead placement was successful using standard guidewires with broad curvatures. Satisfactory acute and follow-up stimulation thresholds and sensing were obtained with the only complication being an intraoperative lead dislodgement, prompting a second ventricular lead. Successful transvenous lead placement across a tricuspid annuloplasty ring is possible.

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PubMed2002

Latent Mahaim fiber as a cause of antidromic reciprocating tachycardia: recognition and successful radiofrequency ablation.

The term "Mahaim fiber" usually is applied to an atriofascicular fiber that inserts distally into the right bundle branch and forms the anterograde limb of a reciprocating tachycardia. One of the features that has been used to describe the physiology of Mahaim fibers is the presence of anterograde preexcitation. We describe two patients who had a clinical tachycardia consistent with a "Mahaim tachycardia" in whom there was no evidence or minimal evidence of anterograde preexcitation during sinus rhythm or atrial pacing. In both patients, the tachycardia was rendered noninducible by radiofrequency ablation at the site of Mahaim potentials at the tricuspid annulus, and a long-term cure was achieved. This is the first description of a "latent Mahaim fiber" that does not cause preexcitation but which can support antidromic reciprocating tachycardia.

Adult↗

PubMed1999

An 'annoying' foot: unilateral painful legs and moving toes syndrome.

The syndrome of painful legs and moving toes is an uncommon condition causing distressing leg pain and is recognised chiefly by the characteristic involuntary movements. This case report describes an unusual unilateral clinical presentation, which led to a delay in diagnosis.

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