Guidewire Tip Research Articles

An In Situ Technique to Retrieve an Entrapped J-Tip Guidewire from an Inferior Vena Cava Filter

An In Situ Technique to Retrieve an Entrapped J-Tip Guidewire from an Inferior Vena Cava Filter

Quantitative assessment of image quality enhancement due to unsharp-mask processing in x-ray fluoroscopy.

Spatial unsharp-mask processing and its variants are commonly used in x-ray radiography to enhance image contrast. We investigated the effect of three unsharp-masking filter kernels of different sizes on the detection of an advanced guidewire tip in simulated x-ray fluoroscopy image sequences. To isolate the effect of visual temporal processing, we repeated the experiments on single images. Filter gains were selected so that all three kernels increased the contrast of a 0.018-in. (0.457-mm) guidewire by a factor of 2 but had different effects on image noise and signal profiles. There was no statistically significant effect of unsharp masking on human-observer performance in single images. However, all three kernels significantly improved average performance in image sequences, and the guidewire contrast required for detection was reduced by 32%-40%. A prewhitening channelized observer model predicted the disparity between sequences and single images and fitted measurements at different kernel sizes well. A nonprewhitening observer model did not. We conclude that unsharp masking is a simple and effective method of improving guidewire visualization in fluoroscopically guided interventional procedures and that quantitative image quality studies are essential for evaluation of image-processing techniques in sequences such as x-ray fluoroscopy.

Optical coherent reflectometry: a new technique to guide invasive procedures.

The success rate of percutaneous transluminal coronary angioplasty for chronic total arterial occlusions is still unsatisfactory. Inability to cross the lesion with a guidewire is a major cause of failure. Optical coherent reflectometry (OCR) is a new method of using laser light to measure the depth of tissue from the end of an optic fiber. This study tests whether an OCR prototype guidewire provides a guidance system that might be useful to assist reopening chronic total arterial occlusions. An OCR fiber optic within a 0.014" hypotube was developed using the interference pattern of two reflected light beams (wave length 1,300 nm). To determine if OCR can distinguish different tissue types, plaques of human lower extremity arterial segments were visually divided into three types (calcified, white, or yellow). The slope of the initial reflectance of the OCR curve was calculated and compared between the three groups. In six other arteries, the OCR wire was advanced longitudinally through occluded human artery segments in vitro. Guidewire position was determined by OCR and compared to the position of the guidewire tip observed simultaneously by intravascular ultrasound (IVUS) imaging. In 16 arterial surface segments, calcified plaques had a significantly steeper slope than white or yellow plaques (-227.2 +/- 82.2; -81.5 +/- 12.9; -103.6 +/- 19.6 dB/mm; P < 0.01). For the determination of the guidewire position, IVUS and OCR corresponded correctly in 82% of 28 measurements. Sensitivity and specificity of OCR for detection of plaque versus the media/adventitia boundary were 79% and 89%, respectively (P < 0.001). OCR can distinguish calcified from noncalcified plaque and may distinguish plaque from the media/adventitia boundary. This technology may be useful as a means to help navigate a guidewire safely through an occluded artery.

Cardiac tamponade in the “new device” era: Evaluation of 6999 consecutive percutaneous coronary interventions

Background The incidence of cardiac perforation and pericardial tamponade appears to be increasing in the era of new coronary interventional devices compared with coronary balloon angioplasty. Methods and Results We reviewed 6999 consecutive percutaneous coronary interventions performed during 1994 to 1996 in a single urban university hospital catheterization laboratory. Data had been collected prospectively as part of an ongoing quality assurance program. Fifteen patients had cardiac tamponade within 36 hours of the procedure. Only 6 of these occurred during the interventional procedure; the others occurred 2 to 36 hours later. The median patient age was 72 years. Nine (60%) patients were female. Three patients received abciximab. Five perforations were at the target coronary artery site, 3 were caused by a guide wire tip in the distal part of the target artery, and 7 represented right ventricular perforations caused by a temporary pacemaker wire. Five of the 7 right ventricular perforations occurred during rotational atherectomy procedures. Diagnosis was aided by immediate echocardiography. Treatment was medical, including pericardiocentesis, in 6 cases. The other 9 patients required surgical drainage and repair. All patients survived the index hospitalization. At 18-month follow-up, 1 patient had died, and all others were without apparent sequelae. Conclusions Tamponade after percutaneous coronary intervention is not rare in the “new device” era (overall incidence 0.2%); tamponade after percutaneous coronary intervention is often delayed and may occur outside the catheterization suite; patients are more likely to be female and elderly; immediate echocardiography is an essential aid to diagnosis and prompt treatment; and the use of temporary right ventricular pacing catheters must be reexamined. (Am Heart J 2000;140:279-83.)

Safety of MRI-guided endovascular guidewire applications.

Magnetic radiofrequency (RF) fields applied during magnetic resonance imaging (MRI) may induce heating in devices made from conductive materials. The present paper reports on theoretical and experimental studies on the RF heating resonance phenomenon of an endovascular guidewire. A nitinol-based guidewire was inserted into a vessel phantom and imaged at 1.5 and 0.2 T with continuous temperature monitoring at the guidewire tip. The heating effects due to different experimental settings were examined. A model is developed for the resonant current and the associated electric field produced by the guidewire acting as an antenna. Temperature increases of up to 17 degrees C were measured while imaging the guidewire at an off-center position in the 1.5 T MR system. Power absorption produced by the resonating wire decreased as the repetition time was increased. No temperature rise was measured at 0.2 T. Considering the potential utility of low-field, open MR systems for MRI-guided endovascular interventions, it is important to be aware of the safety of such applications.

3490 Technical evaluation of two new biliary miniprobes for intraductal ultrasonography.

BACKGROUND: Intraductal ultrasonography (IDUS) using thin ultrasonic probes could be useful in some biliopancreatic indications. Initial prototypes were limited by the size of the probes and their fragility. Insertion was then mainly performed via a transhepatic route. Two new thinner Olympus miniprobes could allow performing IDUS routinely via ERCP. AIM: To evaluate the technical features of these miniprobes. METHODS: UM-S20-20R (SP) with a tip of 1.7 mm and UM G20-29R (SG) with a channel for a 0.035 inches guidewire (tip=2.0 mm) have a 20 MHz frequency. Insertion can be done transpapillary (via ERCP) or percutaneously (via transhepatic route). Limiting factors for the probe insertion and the image quality were studied. RESULTS: 30 intraductal biliary EUS were performed in 25 patients (staging and/or follow-up of ampulla or bile duct tumors: 18; indeterminate biliary stenosis: 8; mucinous producing pancreatic tumor (MPPT): 4). - In 3 cases (Klatskin's tumors) SP was inserted after a percutaneous drainage inside a 12 F catheter, without technical problems; the image quality was not affected by the drain, and the interface was excellent. - In 27 cases a transpapillary insertion was intended. SP was used in 7 cases. Insertion succeeded in 3 sphincterotomized patients but only in 1/4 non sphincterotomized patients. The insertion through a biliary stenosis failed 2/3. SG was used in 20 cases. It was inserted in biliary ducts in 16/16 patients. A precut was once necessary. The insertion inside the wirsung until the tail was performed 4/4 without problem. SG passed through biliary stenosis 13/15. In two Klatskin's tumors one hepatic duct was not catheterized by the guidewire. Two factors hampered the interpretation: - air artifacts (after sphincterotomy and in MPPT) – large tumors (limited penetration depth). No probe rupture was observed. CONCLUSION: 1. The slim probe is a good option for transhepatic route due to its size allowing a smaller diameter for the drainage catheter 2. The miniprobe with guidewire is better for the transpapillary route avoiding sphincterotomy and overcoming stenotic areas. It could now be used routinely during ERCP.

Heating around intravascular guidewires by resonating RF waves.

We examined the unwanted radiofrequency (RF) heating of an endovascular guidewire frequently used in interventional magnetic resonance imaging (MRI). A Terumo guidewire was partly immersed in an oblong saline bath to simulate an endovascular intervention. The temperature rise of the guidewire tip during an FFE sequence [average specific absorption rate (SAR) = 3.9 W/kg] was measured with a Luxtron fluoroscopic fiber. Starting from 26 degrees C, the guidewire tip reached temperatures up to 74 degrees C after 30 seconds of scanning. Touching the guidewire may cause sudden heating at the point of contact, which in one instance caused a skin burn. The excessive heating of a linear conductor like the guidewire can only be explained by resonating RF waves. The capricious dependencies of this resonance phenomenon on environmental factors have severe consequences for predictability and safety guidelines.

Safety of MRI-guided endovascular guidewire applications

Magnetic radiofrequency (RF) fields applied during magnetic resonance imaging (MRI) may induce heating in devices made from conductive materials. The present paper reports on theoretical and experimental studies on the RF heating resonance phenomenon of an endovascular guidewire. A nitinol-based guidewire was inserted into a vessel phantom and imaged at 1.5 and 0.2 T with continuous temperature monitoring at the guidewire tip. The heating effects due to different experimental settings were examined. A model is developed for the resonant current and the associated electric field produced by the guidewire acting as an antenna. Temperature increases of up to 17 degrees C were measured while imaging the guidewire at an off-center position in the 1.5 T MR system. Power absorption produced by the resonating wire decreased as the repetition time was increased. No temperature rise was measured at 0.2 T. Considering the potential utility of low-field, open MR systems for MRI-guided endovascular interventions, it is important to be aware of the safety of such applications.

Intracranial EEG Recording from Intravascular Electrodes in Patients with Temporal Lobe Epilepsy

Purpose: As part of a presurgical extracranial study, we performed intracranial electroencephalographic (EEG) recording by using micro‐guidewires as active intravascular electrodes in two patients with temporal lobe epilepsy in combination with the Wada test. In one case, there was good agreement among information derived from the non‐invasive assessments, such as ictal semiology, interictal and ictal data from long‐term EEG and video monitoring, magnetic resonance imaging (MRI) findings, single photon emission computed tomography (SPECT) findings, and neuropsychological studies, that consistently pointed to one temporal lobe as the epileptogenic region. The other case showed no definite information about the laterality of the epileptogenic region. The interictal scalp EEG for the two cases showed independent, bilateral, anterior to midtemporal spike foci. The ictal EEGs with sphenoidal electrodes showed no apparent changes initially and during simple partial seizures. Methods: After giving informed consent, the patients underwent intracranial EEG recording from intravascular guidewires in combination with the Wada test. With the routine transfemoral catheter technique, two guiding catheters were manipulated into the common carotid arteries via bilateral femoral punctures. These catheters were used not only for the introduction of microcatheters and microguidewires by a “roadmap” technique, but also for the injection of sodium amobarbital for the Wada test. The guidewire tips were advanced 10 mm from the tips of the micro‐catheters, which were placed in the middle meningeal arteries at the level of the foramen spinosum. This distance placed the guidewire tips superficial to the inferior surfaces of the temporal lobes. The proximal end of the steel wire shaft was connected to the recording unit, and the guidewires were used as active intracranial recording electrodes: 10 scalp EEG electrodes were also used to record for ∼1 h, without a sleep tracing. We evaluated the usefulness of this technique by comparison with a simultaneously recorded scalp EEG, and, in addition, with the results of long‐term intracranial EEG recordings. Results: In both cases, intracranial EEG recording from intravascular electrodes revealed frequent spikes and sharp waves from one electrode interictally, but at that time, the scalp EEG revealed no definite paroxysmal discharges except infrequently at the active reference electrode. The laterality of these frequent epileptic discharges was in complete agreement with that of the origin of the ictal discharges recorded from long‐term intracranial EEG electrodes. Conclusions: Currently, the protocol for resections for patients with intractable temporal lobe epilepsy consists of three phases: extracranial studies, long‐term intracranial recording when necessary, and finally surgical resection. Although long‐term intracranial recording is recommended for many patients, the temporal lobectomy may be performed without further invasive EEG studies if there is good agreement among information derived from the noninvasive assessments. For such straightforward cases, if this recording shows interictal discharges on the same side as the noninvasive studies, the outcome of temporal lobectomy may also be improved without further invasive testing and, at least, the reliability of determining the laterality of the epileptogenic focus can be increased. In the cases that have conflicting results from the extracranial studies, it is useful for deciding the side on which the subdural electrodes will be mainly placed. Although the duration of the recording was limited, this technique appears to be very useful because it can be performed easily in the course of angiography without additional invasive steps.

Angioplasty Guidewire Velocity: A New Simple Method to Calculate Absolute Coronary Blood Velocity and Flow

The Thrombolysis In Myocardial Infarction (TIMI) frame count is a relative index of coronary flow that measures time by counting the number of frames required for dye to travel from the ostium to a standardized coronary landmark in a cineangiogram filmed at a known speed (frames/s). We describe a new method to measure distance along arteries so that absolute velocity (length ÷ time) and absolute flow (area × velocity) may be calculated in patients undergoing percutaneous transluminal coronary angiography (PTCA). After PTCA, the guidewire tip is placed at the coronary landmark and a Kelly clamp is placed on the guidewire where it exits the Y-adapter. The guidewire tip is then withdrawn to the catheter tip and a second Kelly clamp is placed on the wire where it exits the Y-adapter. The distance between the 2 Kelly clamps outside the body is the distance between the catheter tip and the anatomic landmark inside the body. Velocity (cm/s) may be calculated as this distance (cm) ÷ TIMI frame count (frames) × film frame speed (frames/s). Flow (ml/s) may be calculated by multiplying this velocity (cm/s) and the mean cross-sectional lumen area (cm 2) along the length of the artery to the TIMI landmark. In 30 patients, velocity increased from 13.9 ± 8.5 cm/s before to 22.8 ± 9.3 cm/s after PTCA (p <0.001). Despite TIMI grade 3 flow both before and after PTCA in 18 patients, velocity actually increased 38%, from 17.0 ± 5.4 to 23.5 ± 9.0 cm/s (p = 0.01). For all 30 patients, flow doubled from 0.6 ± 0.4 ml/s before to 1.2 ± 0.6 ml/s after PTCA (p <0.001). In the 18 patients with TIMI grade 3 flow both before and after PTCA, flow increased 86%, from 0.7 ± 0.3 to 1.3 ± 0.6 ml/s (p = 0.001). Distance along coronary arteries (length) can be simply measured using a PTCA guidewire. This length may be combined with the TIMI frame count to calculate measures of absolute velocity and flow that are sensitive to changes in perfusion. TIMI grade 3 flow is composed of a range of velocities and flows.

Guidewire antennas for MR fluoroscopy.

Before MRI can be used for guiding vascular interventions, the problem of dependably visualizing guidewires must be solved. Ideally, the position and curvature of the tip of the guidewire should be visible to facilitate steering through the vascular system. In this paper, various antennas are described that can be incorporated into a guidewire tip. These antennas allow the guidewire to be visualized with high contrast. Computer simulation and experimental evidence are presented showing the value of adding a passive MR signal source, with a short T1, internal to the coil. The internal source increases the available signal, narrows the apparent width of the guidewire, and allows the use of fast imaging sequences.

A new coaxial needle system, hepatic artery targeting wire, and biplane fluoroscopy to increase safety and efficacy of TIPS.

To improve safety and efficacy of the transjugular intrahepatic portosystemic shunt (TIPS) procedure, we introduced a new, thin-needle (21-gauge long PTC needle) puncture technique using biplane fluoroscopy and targeting of a guidewire tip in the right hepatic artery. After puncture of the right portal vein, a 0.016-inch guidewire was inserted into the portal vein, followed by a 4 Fr dilator. The 4 Fr dilator allowed introduction of a 0.035-inch working guidewire. We successfully performed TIPS in seven patients with postnecrotic cirrhosis using this technique and encountered no technical difficulties or complications.

Measurement of volumetric coronary blood flow by simultaneous intravascular two-dimensional and Doppler ultrasound: Validation in an animal model

We examined the accuracy and feasibility of using simultaneous intracoronary Doppler and two-dimensional (2D) ultrasound imaging in the measurement of volumetric coronary blood flow (CBF). A femoral artery-to-circumflex coronary artery shunt was created in four dogs with tubing that incorporated an in-line transit-time ultrasound (TTU) flow probe. A 2D ultrasound catheter was introduced over a 0.014-inch Doppler guide wire into the circumflex artery with the guide wire tip positioned 2 cm beyond the imaging catheter tip. Cross-sectional area (CSA) and average peak velocity (APV) were recorded. CBF was determined from the previously validated relation CBF = CSA × 0.5 APV and the adjusted measurement formula CBF = CSA × 0.47 APV. Within the 119 measurements made, TTU CBF varied from 31 to 385 ml/min. An excellent correlation was found between 2D/Doppler-derived and TTU CBF with both constants; measurement agreement was improved and bias minimal with the 0.47 constant (slope = 0.9997; r = 0.99; p < 0.0001; SEE = −6.7 ± 8.6). We conclude that simultaneous 2D and Doppler ultrasound yields accurate estimates of volumetric CBF.

Distal Steerable Guidewire Tips may Fracture and Separate

Distal Steerable Guidewire Tips may Fracture and Separate

Esophageal dilation with polyvinyl bougies, using a marked guidewire without the aid of fluoroscopy: an update.

One hundred thirty-eight patients with esophageal stricture underwent polyvinyl bougie dilations whereby American Endoscopy dilators were passed over a marked guidewire that had been placed endoscopically. Fluoroscopy was not utilized during the dilations. The dilations were performed only after the guidewire was properly placed, with 60-cm markings at the incisors, which ensured that the tip of the guidewire was in the antrum. One hundred fourteen patients had benign strictures and 24 had malignant strictures. There were 197 sessions of dilations for a total of 748 individual dilations. In 97 of 138 patients, the guidewire was placed in the antrum under direct vision. The remaining 41 patients had significant esophageal stenosis which prevented passage of the endoscope into the stomach; therefore, the guidewire was placed by advancing it blindly through the stenosis. There were no procedure-related complications. During this period, eight patients were dilated without complications, using fluoroscopic placement of guidewire because endoscopic placement of the guidewire was not considered safe. We conclude that esophageal strictures can be safely dilated in most patients by means of the American Endoscopy dilator system and the marked guidewire without the aid of fluoroscopy.

Coronary angioplasty through 4 French diagnostic catheters.

In 50 consecutive patients subjected to coronary angioplasty immediately following a 4 French (F) diagnostic study, the technical feasibility and economical aspects of angioplasty through 4F catheters of 54 lesions were assessed. The patients were selected, but multiple, eccentric, and long lesions were not a priori excluded. 4F diagnostic catheters (Cordis), and fixed-wire dilatation catheters (Ace, Scimed) were used in all cases. The procedure was successful in 43 lesions (80%) using 4F catheters. For 11 stenoses (20%), a change over to a larger French size was required. Two of these lesions could not be crossed with the balloon despite the larger sized guiding catheter. The final overall success rate was 96%, and there were no major complications. The use of diagnostic 4F catheters for angioplasty in these 50 patients resulted in the saving of 39 guiding catheters and 19 introducer sheaths. For 12 lesions (22%), an additional 4F catheter became necessary since the shape used for the diagnostic study was inadequate for angioplasty. In 7 cases, more than 1 balloon was used, but 5 of these balloon exchanges were independent of the use of 4F catheters. Three exchanges were performed through the 4F catheter (1 for need of a larger balloon to improve on an unsatisfactory angiographic result and 2 for a crimped guide wire tip of the Ace balloon). In the remaining 4, a larger catheter was used; in 2 of them, angioplasty eventually failed (failure to cross lesion) and in the remaining 2, a Monorail system solved the problem, which is incompatible with 4F catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary revascularization by a new coaxially-guided laser-heated metal cap system

The fiberoptic laser-heated metal cautery cap has been used effectively to vaporize coronary and peripheral atherosclerotic plaque obstructions.‘-4 However, easy placement of the thermal cap and safe vaporization of plaque in a coaxial fashion remain a concern.5 After testing several different catheter versions, a new cautery cap design was developed. The catheter consisted of an optical fiber (200 to 400 ccrn core diameter) attached to a metal cap (1 to 2 mm diameter) with a central extruding guide-wire tip (0.014to 0.018-inch diameter, Unicorn Cap-TM, Xintec Inc., Oakland, Calif.) (Fig. 1). This single unit device allows the operator easy placement and maneuverability inside the coronary artery and control of plaque vaporization. The cool tiny flexible guide-wire tip serves to guide

Angled tip of the steerable guidewire and its usefulness in percutaneous transluminal coronary angioplasty.

Theoretical analysis and clinical evaluation of single and multi-angled guidewires as an alternative to widely used J-wires suggested that the major determinants of the wire function are the shortest distance between the tip and a long axis of the wire-reaching distance (RD), angulation of the tip, and the length of the angled arm. Their relationship can be characterized by a formula; reaching distance = sin beta X length of the arm. The two clinically most useful multiple angulations--double and triple angles--were evaluated in 54 patients in whom commercial J-wire failed to pass the lesion in 120 s. This value was compared with an average time of 57.90 +/- 3.9 s needed to pass an angled, individually shaped guidewire from the tip of the guiding catheter through the lesion. (P much less than 0.001 or highly significant.) All patients had tortuous vessels, sharply angled branches, and the largest diameter of the stenosed vessel less than 50% of the largest diameter of the left main coronary artery. Thirty-seven lesions were in the obtuse marginal arteries and 17 in the diagonal arteries. The study suggested that angled guidewires shaped according to described guidelines have superior success to commercial, unshaped J-wires in instrumentation of the tortuous vessels with angled branches and markedly varying diameter.

EKG Guided Placement of Subclavian CVP Catheters Using J-Wire

In an attempt to improve the accuracy of central venous pressure (CVP) catheter tip location, 84 consecutive cardiac surgery patients in sinus rhythm were studied prospectively with respect to subclavian insertion of a CVP catheter using a guidewire technique. The presence of cardiac arrhythmia was used as an index of right atrial (RA) location of the guidewire tip, before threading the catheter over the guidewire. Correct catheter tip location (superior vena cava [SVC] or RA) was achieved in 100% of patients (N = 78) with premature atrial contractions (PACs) related to guidewire insertion. This fell to 50% (N = 4) if no arrhythmias were noted from the guidewire. Ventricular arrhythmias were noted in two of 84 patients (2.4%). Other problems related to the use of this technique are discussed.

Cardiac tamponade following perforation of the left anterior descending coronary system during percutaneous transluminal coronary angioplasty: Successful treatment by pericardial drainage

Percutaneous transluminal coronary angioplasty (PTCA) is an effective and increasingly utilized modality in the treatment of coronary artery disease. Its complications include prolonged angina, myocardial infarction, coronary occlusion, dissection, spasm, embolism, and perforation.’ When these complications occur, immediate aortocoronary bypass surgery is usually performed. We report the occurrence of perforation of a diagonal branch of the left coronary artery with associated cardiac tamponade treated successfully in the Cardiac Catheterization Laboratory without surgical repair of the perforated artery. A 69-year-old white man had a 3-week history of chest pain at rest, which was relieved by nitroglycerin. The patient had nonsustained ventricular tachycardia on an otherwise negative exercise thallium examination. Coronary arteriography revealed a 90% stenosis in the mid-left anterior descending coronary artery and multiple areas of noncritical disease in branches of the left circumflex coronary artery (Fig. 1). PTCA of the left anterior descending artery was performed. Following the intra-arterial administration of 10,000 units of heparin, the standard technique employing a No. 9 FL 4 USC1 (USCI, Billerica, Mass.) guiding catheter was used via the right femoral artery. The left anterior descending coronary artery was entered with a standard steerable ACS (Advanced Cardiovascular Systems, Inc., Temeculla, Calif.) guidewire (size 0.014 inch diameter, 175 cm long) and a 2.5 mm ACS dilatation catheter crossed the lesion. Four dilatations, at a maximum pressure of 8 atm and maximum duration of 15 seconds, were performed. In order to better opacify the area of dilatation and in anticipation of the use of a larger-sized dilatation catheter, with the tip of the dilatation catheter held distal to the area of angioplasty, the steerable guidewire was replaced with a 300 cm long ACS exchange guidewire (0.018 inch diameter). The original dilatation catheter was removed. Angiography of the left coronary artery demonstrated successful angioplasty of the left anterior descending lesion and extravasation of contrast into the pericardial cavity at a site near the tip of the exchange guidewire, several centimeters distal to the area of angioplasty and in the area of a small diagonal branch (Fig. 2). The patient was stable hemodynamically,