Change In Catheter Position Research Articles

AB-453068-1 NOVEL ‘SCORE-MAPPING’ OF DIAPHRAGMATIC COMPOUND MOTOR ACTION POTENTIAL FOR EARLY DETECTION OF PHRENIC NERVE INJURY DURING CRYOABLATION

The proximity of the phrenic nerve to right-sided pulmonary veins makes it susceptible to injury during cryoballoon ablation (CBA) for atrial fibrillation (AF). Although there are no specific preprocedural predictors for phrenic nerve injury (PNI), monitoring of diaphragmatic compound motor action potentials (CMAP) has been used for the early detection of PNI. A 30% drop in CMAP amplitude has been shown in animal and clinical studies as the threshold for the prevention of PNI The aims of this study were to assess the relationship of change in CMAP amplitude with change in score map and then use the automated score map prospectively for early detection of PNI during CBA In the first half of the study, we paced the phrenic nerve at 10,8,6,4,2 milliamperes or till loss of capture in 20 pts. The relationship between the change in amplitude of CMAP with a corresponding change in the score map was studied by linear regression. 30% drop in CMAP amplitude was associated with a score map of 89%(R2 0.77). In the second half of the study, we used a score map threshold of 90% and studied 84 pts. Ablation was stopped if the score map of CMAP dipped below 90% consistently for >4 beats to take respiratory variation into account A total of 174 cryo applications were done for the right-sided veins in 84 pts. A consistent score-map >98% was obtained in all pts before the beginning of the CBA. Ablation had to be stopped in 13 pts due to a drop in the score map or CMAP amplitude or decreased diaphragm contraction. 5 pts had transient PNI. Change in score map was noticeable before change in CMAP amplitude or decrease in diaphragm contraction. In 8 pts drop in the score map was attributed to catheter movement which was noted by the change in catheter position on the 3D mapping system. Score-map of CMAP returned to >98% with catheter adjustment or within 5 minutes of ablation termination along with improvement of CMAP amplitude in all cases. No pts were noted to have persistent PNI at the end of the procedure Beat-to-beat changes in CMAP amplitude can be noted with respiratory variation or catheter movement making it difficult to monitor the change in amplitude. By using an automated score rather than continuously measuring CMAP amplitude, score mapping can make monitoring changes in CMAP amplitude easier. This descriptive study demonstrates that a 90 % score-map threshold correlates with a 30% drop in CMAP amplitude and can be safely and reliably used for the early detection of PNI

Evaluation of interfractional variation of organs and displacement of catheters during high-dose-rate interstitial brachytherapy for gynecologic malignancies

PurposeTo investigate the dosimetric effects due to interfractional changes in catheter position and variation in patient's anatomy during the course of interstitial high-dose-rate (HDR) brachytherapy. Methods and MaterialsA total of 15 patients with either cervical or vaginal cancer underwent interstitial HDR brachytherapy. Interstitial catheters and fiducials were placed under fluoroscopy and intraoperative 3T MRI to confirm the desired catheter placement for adequate target volume coverage. Single plan was generated from first-fraction CT fused with the MRI and used for all fractions of treatment. CT image was acquired before each treatment and registered to the first-fraction CT. Displacement of fiducials and catheters was calculated for each fraction and its effects on dosimetric parameters such as dose covering 90% for high-risk clinical target volume and intermediate-risk clinical target volume and dose to the 2 cm3 of the volume for bladder, rectum, sigmoid, and bowel were studied. ResultsAverage movements of fiducials and catheters were 1.6 mm (range: 0.1–7.1 mm) and 1.7 mm (range: 0.1–4.5 mm), respectively. Overall, deviation of the delivered dose to the target in each fraction was insignificant for all patients (p-value: 0.66 for high-risk clinical target volume and 0.87 for intermediate-risk clinical target volume). The mean dose to organs at risk showed maximum difference up to 0.9, 2.7, 1.6, and 2.1 Gy for bladder, rectum, sigmoid, and bowel, respectively (p-value: 0.88, 0.34, 0.68, and 0.85 for bladder, rectum, sigmoid, and bowel, respectively). ConclusionsThe interfractional dosimetric variation for both target and organs at risk was within clinically acceptable limit throughout the entire course of interstitial HDR-Syed brachytherapy. Only 6% of cases performed replanning, which could be readily identified using CT imaging.

Pilot study evaluating catheter-directed contrast-enhanced ultrasound compared to catheter-directed computed tomography arteriography as adjuncts to digital subtraction angiography to guide transarterial chemoembolization

To investigate the feasibility and procedural value of catheter-directed contrast-enhanced ultrasound (CCEUS) compared with catheter-directed computed tomography arteriography (CCTA) in patients undergoing transarterial chemoembolization (TACE) guided by digital subtraction angiography (DSA). From December 2010 to December 2011, a pilot study was conducted including nine patients (mean age 66.6 years; SD 8.3 years; seven men) undergoing TACE with drug-eluting beads for unresectable hepatocellular carcinoma (HCC). Both CCEUS and CCTA were performed in addition to DSA. Alterations of treatment plan based on CCEUS were recorded and compared with CCTA. CCEUS provided additional information to DSA altering the treatment plan in four out of nine patients (44.4%). In these four patients, CCEUS helped to identify additional tumour feeders (n = 2) or led to a change in catheter position (n = 2). The information provided by CCEUS was similar to that provided by CCTA. CCEUS is a potentially valuable imaging tool in adjunction to DSA when performing TACE and may provide similar information to CCTA.

Assessment of Dosimetric Changes and Adaptive Replanning for Intraoperatively Placed Brachytherapy Applicators during Accelerated Partial Breast Irradiation

Assessment of Dosimetric Changes and Adaptive Replanning for Intraoperatively Placed Brachytherapy Applicators during Accelerated Partial Breast Irradiation

Quantitative Real-time Catheter-based Fluorescence Molecular Imaging in Mice

To prospectively evaluate an optical imaging system designed to perform quantitative, intravital catheter-based imaging of fluorescent molecular probes. This study was performed according to a protocol approved by the institutional animal care committee. A fiberoptic catheter imaging system was developed to implement a normalization algorithm for real-time quantitative near-infrared (NIR) imaging. The system was validated with in vitro imaging of fluorochrome phantoms and in vivo fluorescence measurements obtained in tumors implanted in murine abdomens (n = 7) after administration of an enzyme-activatable NIR probe. Standard analysis of variance tests were used to determine significant dissimilarities in signal from distinct fluorochrome concentrations. The clinical utility of the system was further evaluated by imaging orthotopically implanted murine colonic adenocarcinomas (n = 4). Raw NIR fluorescence intensities, which were measured with a fiberoptic catheter placed above wells of varying NIR fluorochrome concentration, varied markedly (>100%) with catheter position, while the corrected NIR signal was confined to a range of values within 10% of their mean for each individual fluorochrome concentration and were significantly distinct (P < .001) between relevant concentration ranges. Similar results were observed for the in vivo measurements from the abdominally implanted tumors, with raw NIR signal varying 20% from the mean and corrected NIR signal varying only 1% from the mean. The colonic studies revealed that the correction method was robust enough for use during minimally invasive imaging procedures. The authors have developed and implemented a method for quantitative real-time catheter-based fluorescence imaging that resolves NIR signal dependence on changes in catheter position.

Para-Hisian pacing: Useful clinical technique to differentiate retrograde conduction between accessory atrioventricular pathways and atrioventricular nodal pathways

Para-Hisian pacing is a useful tool to differentiate between retrograde conduction over an accessory pathway and retrograde conduction over the fast or slow atrioventricular (AV) nodal pathways. 1-3 Para-Hisian pacing uses right ventricular (RV) pacing close to the His bundle or proximal right bundle branch (RBB). As the position of the ventricular pacing catheter changes subtly during respiration (or by changing pacing output), the pacing stimulus changes capture among (1) basal anteroseptal RV plus His bundle or proximal RBB (His bundle-RBB capture); (2) capture of basal anteroseptal RV alone; and (3) His bundle-RBB capture alone. These changes in pacing capture result in abrupt changes in the timing of His bundle activation relative to the timing of ventricular activation. The presence or absence of a change in atrial activation sequence, stimulus-atrial (SA) intervals, and His bundle-atrial (HA) interval identifies whether retrograde conduction is dependent on ventricular activation (retrograde conduction over an accessory pathway) or His bundle activation (retrograde conduction over the AV node) or both (accessory pathway and AV node; Figures 1 and 2). The loss of His bundle-RBB capture is usually identified by the widening of the QRS complex, indicating that some of the ventricular myocardium (farthest from the RV basal septal pacing site) is activated by the His-Purkinje system during both RV and His bundle-RBB capture. Our preferred approach is to position the RV pacing catheter toward the RV outflow tract, 1‐2 cm superior to the His bundle catheter. While pacing at moderate output (5‐10 mA and 2 ms pulse width), the RV catheter is slowly withdrawn toward the His bundle catheter (proximal RBB) until intermittent His bundle-RBB capture occurs because of changes in catheter position during respiration. As the pacing catheter is moved closer to the His bundle, the ventricular potential in the His bundle electrogram becomes earlier and the retrograde His bundle potential becomes later, providing greater separation between the local ventricular and His bundle potentials. The use of closely spaced electrodes (1 mm edge-to-edge) on the His bundle catheter shortens the duration of the local ventricular potential in the His bundle electrogram, preventing the masking of the His bundle potential by the local ventricular potential. Closely spaced electrodes on the pacing catheter may provide a smaller pacing field, facilitating intermittent loss of His bundle-RBB capture with small changes in catheter position during respiration. A deflectable RV pacing catheter is positioned more easily for para-Hisian pacing and subsequent positioning of the pacing catheter close to the location of an accessory pathway (Figure 3A). In patients with proximal RBB block (such as resulting from previous ablation), His bundle-RBB capture requires pacing proximal to the RBB block site and may not be achieved from the RV. Other approaches include changing pacing output to achieve intermittent His bundle-RBB capture and use of the distal electrodes on the His bundle catheter for pacing. 4

Changes in Tunneled Catheter Tip Position when a Patient Is Upright

To determine the relative changes in position of tunneled catheters from supine to upright patient position and factors affecting catheter tip migration. One hundred forty-six different tunneled catheters were placed through the subclavian or jugular veins radiologically, and catheter positions were documented with use of cine radiography at the time of placement. Follow-up chest radiographs were obtained with the patient in the upright position within 48 hours after placement. Catheter tip positions were numbered from 1 to 8, with 1 representing the innominate/superior vena cava junction and 8, the lower right atrium. Patient sex and weight, the site of catheter entry, and the size and type of catheter were correlated with the relative change in position on the follow-up chest radiogrpahs. There was a statistically significant (P < .0001) change in catheter position on the follow-up chest radiographs, with a mean difference of 1.5 catheter positions (usually mid-right atrium initially to low superior vena cava on follow-up). Catheter tip migration was greater for catheters in the subclavian veins, in females, and in obese patients. The catheter tip migrates significantly from the initial position at the time of placement as compared to when the patient assumes the upright position. This knowledge is important in achieving the desired final catheter position.

Changes in the position of epidural catheters associated with patient movement.

Epidural catheter movement has been noted with change of patient position and can result in inadequate anesthesia. This study was designed to measure movement and to develop a technique that minimizes catheter displacement. In 255 parturients requesting epidural anesthesia for labor or cesarean section, a multiorificed lumbar epidural catheter was inserted with the patient in the sitting flexed position. The distance to the epidural space, length of catheter inserted, and amount of catheter position change as the patient moved from the sitting flexed to sitting upright and then to the lateral decubitus position were measured before the catheter was secured to the skin. Adequacy of analgesia, the need for catheter manipulation, and whether the patient was considered obese were noted. Data were grouped according to body mass index (BMI): < 25, 25-30, and > 30 kg/m2. The groups did not differ with respect to the length of catheter initially inserted or changes in catheter position between initial taping and removal. The distance to the epidural space differed significantly among the groups, increasing with greater BMI. Catheters frequently appeared to be drawn inward with position change from the sitting flexed to lateral decubitus position, with the greatest change seen in patients with BMI > 30. Only nine catheters were associated with inadequate analgesia, four of which were replaced. No analgesic failures occurred in the BMI > 30 group. In patients judged by the anesthesiologist to be obese or to have an obese back, BMI was greater, and distance to the epidural space and the magnitude of catheter movement with position change were greater than in those who were not obese. Epidural catheters moved a clinically significant amount with reference to the skin in all BMI groups as patients changed position. If catheters had been secured to the skin before position change, many would have been pulled partially out of the epidural space. To minimize the risk of catheter displacement, particularly in obese patients, we recommend that multiorificed catheters be inserted at least 4 cm into the epidural space and that patients assume the sitting upright or lateral position before securing the catheter to the skin.

Left Coronary Artery Dissection with an Amplatz-Shaped Catheter: The Role of Vigorous Inspiration during Contrast Injection

We present a case of iatrogenic left main coronary artery dissection during selective coronary arteriography in which the dissection was likely precipitated by respiratory-induced changes in catheter position. We further comment on changes in technique which may have averted the dissection.

Electrocardiographic diagnosis of pacemaker catheter displacement

Displacement of permanent pacemaker catheters occurs in about 10 per cent of primary implantations, and can be a cause of “pacemaker failure.” If movement of the catheter tip is 2 cm. or less there is usually no change of the stimulus artifact on the standard ECG, but marked changes in catheter position do result in changes of the amplitude and direction of the pacemaker stimulus artifact. Four episodes of catheter displacement resulted in changes of the stimulus artifact vector direction of greater than 90 degrees in either the frontal or horizontal planes. Rapid screening of the routine ECG is an effective means of detecting catheter displacement, with or without loss of pacing.

Diaphragmatic Origin of the Pacemaker Sound

The late onset of diaphragmatic stimulation without apparent intercostal muscle stimulation caused a pacemaker sound in a patient with a transvenous pacemaker in the absence of obvious myocardial perforation. In this situation the pacemaker sound does not invariably indicate myocardial perforation. Serial ventricular electrograms may be helpful in detecting changes in catheter position and in the diagnosis of myocardial perforation. Some manipulation of the pacing catheter is often required to eliminate uncomfortable diaphragmatic stimulation whether or not perforation has occurred. The late onset of diaphragmatic stimulation without apparent intercostal muscle stimulation caused a pacemaker sound in a patient with a transvenous pacemaker in the absence of obvious myocardial perforation. In this situation the pacemaker sound does not invariably indicate myocardial perforation. Serial ventricular electrograms may be helpful in detecting changes in catheter position and in the diagnosis of myocardial perforation. Some manipulation of the pacing catheter is often required to eliminate uncomfortable diaphragmatic stimulation whether or not perforation has occurred.