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  • 1
    Electronic Resource
    Electronic Resource
    Single Catheter Determination of Local Electrogram Prematurity Using Simultaneous Unipolar and Bipolar Recordings to Replace the Surface ECG as a Timing Reference (2001)
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 24 (2001), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: DELACRETAZ, E., et al.: Single Catheter Determination of Local Electrogram Prematurity Using Simultaneous Unipolar and Bipolar Recordings to Replace the Surface ECG as a Timing Reference. Bipolar recordings eliminate much of the far-field signal, while minimally filtered unipolar recordings contain substantial far-field signal components. These properties may allow the onset of the unipolar recording to serve as a timing reference for the bipolar recording obtained from the same electrode catheter during mapping of focal atrial or ventricular tachycardias. Mapping and RF ablation were performed in 26 patients with focal ventricular tachycardia and 14 patients with focal atrial tachycardia. At 205 mapping sites, simultaneous recordings of (1) minimally filtered unipolar electrograms (0.5–500 Hz), (2) high pass filtered unipolar electrograms (100 Hz), and (3) filtered bipolar recordings (30–500Hz) were analyzed. The interval between the onset of the minimally filtered unipolar electrogram and the first peak of the bipolar electrogram (UniOn - Bip) correlated closely with the timing of the local electrogram referenced to the surface ECG (r = 0.85, P 〈 0.001). Of 53 sites where RF ablation was performed, UniOn - BiP was shorter at successful compared to unsuccessful sites (3.8 ± 3.5 vs 9.2 ± 5.2ms, P 〈 0.001) and was 〈 15 ms at all successful sites. In conclusion, the comparison of simultaneous unipolar and bipolar electrograms from a single catheter allows assessment of the prematurity of local electrograms from a focal source without the use of the P wave or QRS onset as a timing reference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2001.00441.x
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  • 2
    Electronic Resource
    Electronic Resource
    Ablation Lesion Size Correlates with Pacing Threshold: (2004)
    350 Main Street , Malden , MA 02148-5018 , USA and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Pacing and clinical electrophysiology 27 (2004), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The virtual electrode model predicts that pacing stimulus strength should reflect proximity of the pacing electrode to excitable myocardium, allowing pacing threshold to assess radiofrequency (RF) ablation lesions and unexcitable scar. The purpose of this study is to correlate RF lesion size with pacing threshold and electrogram (EG) amplitude change at the ablation site. In four swine (32–58 kg, 20 ventricular RF lesions were created using a 4-mm tip electrode catheters under fluoroscopic and electroanatomic guidance. Unipolar pacing threshold and bipolar and unipolar EG amplitude were measured before and after ablation and compared with lesion size measured in the fixed, serially sectioned tissue. Lesion diameter ranged from 6.4 to 19 mm and volume ranged from 29 to 1920 mm.3 Ablation increased the pacing threshold by 320%, from 0.9 ± 0.3 to 3.6 ± 2.6 mA, P 〈 0.001. The change in pacing threshold correlated with lesion volume R = 0.88, P 〈 0.001). Linear regression predicts that lesion volume (mm3) = 160 X rise in pacing threshold + 13. Ablation reduced peak to peak bipolar EG amplitude by 56%, from 2.5 ± 2.0 mV to 1.1 ± 0.6 mV (P = 0.005). Unipolar EG amplitude diminished by only 22% from 4.0 ± 1.6 to 3.2 ± 0.9 mV postablation (P = 0.005). The correlations of lesion volume with change in either bipolar R = 0.14, P = 0.6) or unipolar R = 0.18, P = 0.6) EG amplitude were poor. Pacing threshold correlates with RF ablation lesion size, consistent with the virtual electrode model. In normal myocardium, change in pacing threshold is likely to be a better marker of lesion size than electrogram amplitude. (PACE 2004; 27:933–937)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.2004.00561.x
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  • 3
    Electronic Resource
    Electronic Resource
    Deep Myocardial Ablation Lesions Can Be Created with a Retractable Needle-Tipped Catheter (2004)
    350 Main Street , Malden , MA 02148-5018 , USA and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 27 (2004), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: RF catheter ablation of ventricular tachycardia is sometimes limited by inadequate lesion depth. This study investigated the use of a retractable needle-tipped catheter to create deep RF lesions in vivo in porcine myocardium. An 8 Fr electrode catheter with an extendable 27-gauge needle at the tip was modified for RF ablation by embedding a thermocouple and attaching a pin connector. In three swine (32–58 kg) the left ventricle was entered via the femoral artery and endocardial contact was made. The needle was advanced 10 mm and 13 RF applications were made under a controlled temperature (90°C × 120 s). Nine control lesions were made using a standard 4-mm tip catheter (60°C × 120 s). The lesions were fixed, serially sectioned from the endocardium, digitally imaged, and quantified. Needle ablation lesions were deeper (10.15 ± 0.77 vs 5.67 ± 0.37 mm, P 〈 0.001) and more likely to be transmural (77 vs 11%, P = 0.008) than control lesions. The volume of control lesions, however, was larger (358.4 ± 56.2 vs 174.7 ± 18.6 mm3, P = 0.002) due to a significantly larger cross-sectional area at the endocardium (0.548 ± 0.04 vs 0.151 ± 0.01 cm2, P 〈 0.001). At depths 〉 6 mm, the needle electrode lesions had a greater cross-sectional area (0.136 ± 0.01 vs 0.005 ± 0.004 cm2, P 〈 0.001). Catheter-based needle ablation is feasible and allows creation of deeper lesions that can be transmural. Although deep, the lesions had a small cross-sectional area such that precise targeting would be required for success. (PACE 2004; 27:594–599)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.2004.00492.x
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  • 4
    Electronic Resource
    Electronic Resource
    Assessment of Radiofrequency Ablation Effect From Unipolar Pacing Threshold (2003)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Methods for determining if an ablation lesion has been created by RF current application are limited, but needed. This study sought to determine if a change in pacing threshold at the ablation site might be used to assess creation of an ablation lesion. Peak-to-peak amplitude of the bipolar electrogram (EGM) and the unipolar pacing threshold were determined before and after creation of RF lesions using irrigated tip (63 lesions in 11 patients) or conventional ablation catheters (33 lesions in 9 patients) in infarct scars for ablation of ventricular tachycardia. The threshold was measured during continuous pacing at a cycle length of 600 ms by a decrementing output current at a pulse width of 2 ms. The unipolar pacing threshold increased by 254 ± 248% (from 5.7 ± 3.5 to 15.1 ± 6.7 mA, P 〈 0.001 ) after irrigated tip ablation and by 155 ± 144% (from 5.9 ± 3.4 to 12.3 ± 5.7 mA, P 〈 0.001 ) after conventional ablation ( P 〈 0.05 for irrigated tip vs conventional). EGM amplitude decreased by 17 ± 27% (from 0.39 ± 0.32 to 0.30 ± 0.21 mV ) after irrigated tip ablation and by 16 ± 24% (from 0.48 ± 0.27 to 0.41 ± 0.20 mV ) after conventional ablation (irrigated tip vs conventional, P = NS). There was no correlation between the change in bipolar EGM amplitude and the pacing threshold. An increase in unipolar pacing threshold is a marker of lesion creation. In regions of infarction, the relative change in threshold produced by ablation is substantially larger than the change in bipolar electrogram amplitude. The greater increase in pacing threshold after irrigated tip ablation compared to conventional ablation suggests that the magnitude of change reflects lesion size. (PACE 2003; 26:1993–1996)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2003.00307.x
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  • 5
    Electronic Resource
    Electronic Resource
    Device to promote pelvic floor muscle training for stress incontinence (2003)
    Melbourne, Australia : Blackwell Science Pty
    International journal of urology 10 (2003), S. 0 
    Details
    ISSN: 1442-2042
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim:  Many patients with stress urinary incontinence do not have enough motivation to continue pelvic floor muscle training (PFMT) by themselves. Therefore, a device was created to support PFMT, and its effect was examined.Methods:  Forty-six women with stress urinary incontinence were assigned to a control group or a device group in order of presentation. A pamphlet on PFMT was given to control patients, while the same pamphlet plus the device and instructions on its use were given to patients in the device group. The device had a chime that was set to sound three times a day when exercise sessions were scheduled. PFMT consisted of fast and slow pelvic floor muscle contraction exercises that were performed for 2 min and followed a rhythm set by the device.Results:  After 8 weeks, 20 patients from the control group and 21 patients from the device group could be evaluated. In the control group, only the quality of life (QOL) index improved significantly. In the device group, however, the daily number of incontinence episodes, the number of pads used daily, the QOL index, and the pad weight in the pad test improved significantly. Patients in the device group said that they felt obligated to perform PFMT when the chime sounded. Forty-eight percent of patients from the device group were satisfied with the outcome of PFMT, while only 15% were satisfied in the control group.Conclusion:  This device may be useful to support the management of stress urinary incontinence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1442-2042.2003.00659.x
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  • 6
    Electronic Resource
    Electronic Resource
    Trans-mesosigmoid cutaneous ureterostomy (2000)
    Melbourne, Australia : Blackwell Science Pty
    International journal of urology 7 (2000), S. 0 
    Details
    ISSN: 1442-2042
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background : A new method was developed in order to create a single stoma cutaneous ureterostomy in which both ureters traverse the abdominal cavity and yet are buttressed by the mesosigmoid and covered by its visceral peritoneum. Methods : The long mesenterium which is attached to the most mobile part of the sigmoid colon was used for the bilateral ureteral pathway. Tunnels for the ureteral path were made just underneath the visceral peritoneum on the bilateral side of the mesosigmoid. Through the tunnels both ureteral ends were brought from the retroperitoneal space to the mesenterocolonic junction (MCJ) and the MCJ is then approximated and sutured to the inside of the ureteral tract through the abdominal wall. The ureters brought outside the skin, are conjoined and sutured to the V skin flap. Eight patients who carried a high risk for operation and/or had a bladder tumor judged to be incurable underwent this cutaneous ureterostomy. Results : All cases except one with low urinary output could be managed without catheter indwelling during the follow-up period. Three patients suffered from paralytic ileus and one required laparotomy for mechanical ileus during the short postoperative period. Postoperative excretory urography evaluated 14 kidneys during the follow-up period from 2 to 61 months and showed normal upper urinary tract in 11 and a mildly hydronephrotic tract in three. Conclusions : Transmesosigmoid cutaneous ureterostomy provides a single catheterless stoma even when the available ureters are relatively short. It appears to be a good method for supravesical urinary diversion when indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1442-2042.2000.00148.x
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  • 7
    Electronic Resource
    Electronic Resource
    Catheter Ablation of Accessory Atrioventricular Connection between Right Atrial Appendage to Right Ventricle (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 9 (1998), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Accessory AV Connection Between RAA and RV. A 24-year-old woman had experienced frequent attacks of orthodromic AV reciprocating tachycardia. The polarity of the delta waves suggested a right anterior or anterolateral accessory pathway. After ablation at the tricuspid annulus was unsuccessful, earliest retrograde atrial activation was recorded on the floor of the right atrial appendage, 2 cm above the tricuspid ring. Application of radiofrequency en-ergy at this site aholished accessory pathway conduction. This unusual accessory pathway, located between the floor of the right atrial appendage and the right ventricle, was amenable to radiofrequency catheter ablation from within the right atrial appendage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1998.tb01846.x
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  • 8
    Electronic Resource
    Electronic Resource
    A Case of Widely Split Double P Waves with Marked Intra-Atrial Conduction Delay (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 8 (1997), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Widely Split Double P Wave. We report a 78-year-old man as the first documented case of double P waves separated by 400 msec on 12-lead ECG. These P waves had different polarities on lead V1. The first P wave represented activation of the lateral wall of the right atrium, and the latter P wave represented activation of the nudial right atrium and the left atrium. Widely spaced double potentials were recorded craniocaudally along the line, presumably corresponding to the crista terminalis during sinus rhythm. For this to occur, conduction disturbance has to be present both in the upper and lower right atrium. Conduction disturbance in the upper right atrium would interrupt excitation from the sinus node to the medial wall, and conduction disturbance in the lower right atrium would interrupt excitation spreading from the lower lateral right atrium to the isthmus area where fragmented potentials were recorded. These multiple discrete lesions appear to constitute a unique electrical atriopathy in this patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1997.tb01021.x
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  • 9
    Electronic Resource
    Electronic Resource
    Identification and Ablation of Three Types of Ventricular Tachycardia Involving the His-Purkinje System in Patients with Heart Disease (2004)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 15 (2004), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Ventricular tachycardia (VT) with involvement of the His-Purkinje system (HPS) can be difficult to recognize in patients with heart disease, but it may be particularly susceptible to ablation targeting the HPS. This study defines the incidence and types of HPS involvement in VT. Methods and Results: Involvement of the HPS was sought during electrophysiologic study with catheter mapping in 234 consecutive patients referred for catheter ablation of recurrent VT associated with heart disease. HPS VT was observed in 20 (8.5%) patients (mean ejection fraction 29%± 17%); in 9 (11%) of 81 patients with nonischemic heart disease and 11 (7.1%) of 153 patients with coronary artery disease (P = NS). Three types of HPS VT were observed: 16 patients (group 1) had typical bundle branch reentry, 2 patients (group 2) had bundle branch reentry and interfascicular reentry, and 2 patients (group 3) had VT consistent with a focal origin in the distal HPS. In all three groups, the VT QRS had morphologic similarity to the sinus rhythm QRS. Ablation of HPS VT was successful in all patients in whom it was attempted but produced high-degree AV block in 6 (30%). In 12 patients (60%), other VTs due to reentry through scar also were inducible. Conclusion: Involvement of the HPS in VT associated with heart disease has three distinct clinical forms, all of which are susceptible to ablation. Ablation often is not sufficient as the sole therapy due to other induced VT's and conduction abnormalities, requiring pacemaker and/or defibrillator implantation. (J Cardiovasc Electrophysiol, Vol. 15, pp. 52-58, January 2004)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2004.03189.x
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  • 10
    Electronic Resource
    Electronic Resource
    Identification of Left Atrial Origin of Ectopic Tachycardia During Right Atrial Mapping: (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 11 (2000), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Left Atrial Ectopic Tachycardia. Introduction: The high posteromedial right atrium is adjacent to the left atrium near the right superior pulmonary vein. We hypothesized that analysis of electrograms at this site could distinguish left from right atrial tachycardia. Methods and Results: Atrial mapping was performed in 16 patients with left atrial origin ectopic tachycardia (11 patients with right superior pulmonary vein origin and 5 patients with other left atrial tachycardias). During left atrial tachycardia, earliest right atrial activation was recorded at the high posterior right atrium in 14 of 16 patients. At all of these 14 early sites, double potentials were recorded during tachycardia. The first potential was a far-field signal from left atrium as indicated by the following: (1) during sinus heats, the timing of the two potentials reversed such that the left atrial one was late; (2) ablation at the right atrial site did not decrease the amplitude of the first potential, but did decrease the amplitude of the second potential; and (3) the timing of activation at the adjacent left atrium agreed with that of the first potential. In the 11 right superior pulmonary vein tachycardias, the first potential was markedly earlier than the p wave onset, but in left atrial tachycardias with other origins it was later. In a control group of six patients with pacing to simulate right atrial tachycardia, double potentials were recorded In the posterior right atrium, but the timing of components did not reverse during sinus rhythm. Conclusion: For some left atrial ectopic tachycardias, particularly those originating from the right superior pulmonary vein, recognition of left versus right atrial origin can be accomplished during right atrial mapping by analysis of double potentials in the posteromedial right atrium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.2000.tb00169.x
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