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J M Feuer

Publications and source records attributed to J M Feuer.

5 recordsLinked to original sources
PubMed1992

Catheter optimization during contrast ventriculography: a prospective randomized trial.

Although newer contrast mediums have improved hemodynamic stability during left ventriculography, the image quality and hence the diagnostic yield of the procedure is largely determined by the choice of catheter and injection technique. In this study 125 patients were prospectively assigned at random to undergo ventriculography using either of two pigtail catheters, one with a straight shaft throughout its length (straight) and one with a 145-degree bend placed 6.5 cm from the distal end (angled). Injectate composition, flow rate, and volume were held constant for all injections, and baseline clinical and catheterization variables were found to be similar in each group. The angled catheter exhibited a statistically superior ease of insertion (p = 0.038) and took less time to position (p = 0.012), saving a mean of 23 seconds of fluoroscopy time per procedure. It was also associated with superior contour edge definition (p = 0.037) and a trend toward more uniform distribution of contrast medium (p = 0.089). Compared with the straight catheter, the angled catheter was less frequently accompanied by artifactual mitral regurgitation (p = 0.038) but was equally likely to provoke ventricular arrhythmias during injection. These observed differences may be explained in part by the tendency for angled catheters to more frequently localize in the central as opposed to the inferoposterior region of the left ventricular cavity (mean distance from center = 0.53 vs 1.10 cm, respectively; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1990

Alternate methods for the determination of atrial capture threshold utilizing the telemetered intracardiac electrogram.

Periodic determination of pacemaker capture threshold is important to ensure appropriate pacemaker function. During dual chamber pacing, it is sometimes difficult to identify evidence of atrial depolarization on surface electrocardiography (ECG), and this can interfere with the ability to ascertain atrial capture. We describe new methods for determining atrial capture threshold using a standard telemetered endocardial atrial electrogram (AEGM). For the first method, the atrial output is decremented until loss of atrial capture is demonstrated by the appearance of native P wave activity on the AEGM. The atrial capture threshold can then be accurately determined as the point at which a stepwise increase in atrial output results in extinction of the native P wave activity. The second method uses the direct visualization of the AEGM recorded between the ring electrode and pacemaker generator during unipolar (lead tip electrode) pacing. This requires the presence of a bipolar lead. Using this method of recording, it is possible to identify a signal after the atrial stimulus artifact during atrial capture, which disappears with loss of capture. This signal is consistent with a paced "evoked atrial potential" and allows verification of atrial capture. After validating the methods in two sets of test patients with clearly identifiable atrial depolarization on surface ECG, one method was successfully applied to a patient in whom atrial depolarization could not be reliably ascertained on surface ECG. These methods promise to be useful in selected patients in whom confirmation of atrial capture would otherwise be difficult.

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PubMed1989

Variation in P wave amplitude immediately after pacemaker implantation: possible mechanism and implications for early programming.

The P wave amplitude (PWA) plays an important role in determining atrial sensing capabilities. To assess early PWA change, we compared the unipolar PWA in 43 patients at the time of atrial lead placement, measured by a pacing systems analyzer, to the unipolar PWA recorded at the end of pacemaker surgery, from telemetered atrial endocardial electrograms. Individual PWA varied from a decrease of 5.2 mV to an increase of 2 mV (-63% to 267%). In 33 patients with active fixation leads, the implant PWA was 1.96 +/- 0.99 mV versus 2.4 +/- 1.4 mV after surgery. In 11 patients with passive fixation leads, the implant PWA was 2.8 +/- 1.9 mV versus 1.9 +/- 0.8 mV after surgery. The PWA change, measured as the difference between the postsurgical and implant PWA was 0.43 +/- 0.8 mV in active versus -0.86 +/- 1.6 mV in the passive fixation lead groups (P less than 0.05). Considerable change in individual P wave amplitude can therefore occur very early after pacemaker implantation. The direction differs significantly between active (predominantly positive) and passive fixation groups (predominantly negative). These data suggest that an adequate margin of safety is important when initially programming atrial sensitivity, particularly when using passive fixation leads.

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