Reference Catheter Research Articles

Atrial Flutter with Alternating Cycle Lengths: Mechanism and Mapping

A 69-year-old woman with a 10-year history of paroxysmal atrial fibrillation was initially treated with propafenone and amiodarone. Four years ago her arrhythmia burden worsened and she developed recurrent episodes of symptomatic persistent atrial fibrillation. After several cardioversions, she was referred to our institution for radiofrequency catheter ablation. Her amiodarone was discontinued, and 1 year ago she underwent radiofrequency catheter ablation using a pulmonary vein antral isolation approach. Unfortunately, she developed recurrent atrial fibrillation and remained extremely symptomatic despite adequate control of her heart rate. Six months ago, she underwent a second radiofrequency catheter ablation procedure. Electrophysiology study revealed recurrent conduction between all four pulmonary veins and the left atrium, and the veins were reisolated and linear ablations were performed on the roof of the left atrium and the cavotricuspid isthmus. After the ablation, no atrial tachycardia or atrial fibrillation could be induced with aggressive pacing protocols. Unfortunately, she developed recurrent persistent atrial fibrillation within 1 week of the procedure. Four months later she underwent cardioversion with initiation of dofetilide. Two days after starting dofetilide she developed atypical atrial flutter and was referred for a third electrophysiology study. Surface ECG revealed upright P waves in leads V1 and V2 but were poorly seen in the other leads. At electrophysiology study, a circular mapping catheter placed in the four pulmonary veins demonstrated no electrical activity during atrial tachycardia, confirming adequate pulmonary vein isolation. At baseline the atrial tachycardia had stable alternating cycle lengths of 365 ms and 410 ms. Initial pacing maneuvers from the anterolateral right atrium and the proximal and distal coronary sinus yielded post-pacing intervals with long return cycle lengths. In addition, constant fusion and progressive fusion during pacing from the right atrium and the coronary sinus were observed. In order to delineate the tachycardia circuit a 64-electrode basket catheter was placed in the posterior left atrium (Figure 1). At baseline, electrograms could be recorded for 318 ms of the 363-ms and 411-ms cycle lengths (88% and 77% respectively) over a large area in the posterior left atrium. The deflection of the P wave corresponded to activation of the superior and anterior portions of the left atrium. We mapped the tachycardia circuit by identifying the initial site of cycle length change that localized the critical isthmus to the posterior roof of left atrium near the right superior pulmonary vein (Figure 2). When the mapping catheter was moved septally or laterally, split potentials suggestive of a line of conduction block were observed and a 20-electrode catheter revealed a fractionated electrogram that was the first site of cycle length change. Unfortunately, adequate capture could not be obtained despite pacing at maximal outputs from either electrode pair 17 and 18 of the 20-electrode reference catheter or an ablation catheter placed at the same fluoroscopic site. In addition, despite maximal gains, low amplitude electrograms could not be recorded with the The authors report no conflicts of interest for the published content. Manuscript received January 23, 2012, final version accepted February 13, 2012. Address correspondence to: Fred M. Kusumoto, MD, Electrophysiology and Pacing Service, Division of Cardiovascular Disease, Mayo Clinic, 4500 San Pablo Ave, Jacksonville, FL 32224. E-mail: Kusumoto.fred@mayo.edu The Journal of Innovations in Cardiac Rhythm Management, 3 (2012), 727–730

Prostate HDR brachytherapy catheter displacement between planning and treatment delivery

Background and purposeHDR brachytherapy is used as a conformal boost for treating prostate cancer. Given the large doses delivered, it is critical that the volume treated matches that planned. Our outpatient protocol comprises two 9Gy fractions, two weeks apart. We prospectively assessed catheter displacement between CT planning and treatment delivery. Materials and methodsThree fiducial markers and the catheters were implanted under transrectal ultrasound guidance. Metal marker wires were inserted into 4 reference catheters before CT; marker positions relative to each other and to the marker wires were measured from the CT scout. Measurements were repeated immediately prior to treatment delivery using pelvic X-ray with marker wires in the same reference catheters. Measurements from CT scout and film were compared. For displacements of 5mm or more, indexer positions were adjusted prior to treatment delivery. ResultsResults are based on 48 implants, in 25 patients. Median time from planning CT to treatment delivery was 254min (range 81–367min). Median catheter displacement was 7.5mm (range −2.9–23.9mm), 67% of implants had displacement of 5mm or greater. Displacements were predominantly caudal. ConclusionsCatheter displacement can occur in the 1–3h between the planning CT scan and treatment. It is recommended that departments performing HDR prostate brachytherapy verify catheter positions immediately prior to treatment delivery.

Clinical evaluation of a newly developed catheter (SpeediCath Compact Male) in men with spinal cord injury: residual urine and user evaluation

To evaluate the performance of a new 30-cm-long, telescoping male intermittent catheter (SpeediCath Compact Male; Coloplast A/S, Humlebæk, Denmark) in urinary bladder emptying, safety and subject acceptance vs a standard-length male intermittent catheter (SpeediCath). In a prospective, randomized, multicenter, crossover non-inferiority study, 37 male intermittent catheter users self-catheterized three times with the test catheter on one test day and three times with the standard-length male (reference) catheter on another test day. Residual urine (RU) volume in the bladder after catheterization was measured by ultrasound. Safety was assessed in the entire study period in terms of adverse events (AEs) and adverse device events (ADEs). Subjects evaluated their experience, sensation, disposal, bleeding and discomfort with the test and reference catheters and final catheter preference. SpeediCath Compact Male did not differ from the reference catheter in terms of performance (bladder emptying). The upper confidence limit of the mean difference between absolute RU volumes for the test and reference catheter groups did not exceed a pre-established non-inferiority limit of 20 ml, thereby showing the test catheter's non-inferiority to the reference catheter (that is, no worse at bladder emptying). The only AE/ADE reported was one instance of mild urethral burning for 30 min after catheterization, which was judged possibly related to the test catheter but resolved quickly. The SpeediCath Compact Male catheter is as efficient as a conventional intermittent catheter (SpeediCath) at emptying the bladder with the additional benefit of being more discreet and easier to use.

Do Prostate HDR Brachytherapy Catheters Shift between Planning and Treatment Delivery?

Do Prostate HDR Brachytherapy Catheters Shift between Planning and Treatment Delivery?

1.04] Analysis of encrustation of double-J catheters with optical coherence tomography (OCT)

Objective Encrustation of pigtail catheters with crystalline deposit of urine components is a well-known problem and in addition to lower urinary tract infection, the most common complication of any material placed in the urinary tract. There is neither any data about the beginning of encrustation in literature, nor about location or progression. The aim of this study is to make an analysis of the level of encrustation and to document the longitudinal progression with OCT. Material and methods Fourteen double-J (DJ) catheters (Neomedical Ch 7/28 cm) with different indwelling times were compared with a new DJ catheter as a reference, after removal. The external surfaces of the catheters were examined using endoscopic surface OCT (Imalux) and the intraluminal surfaces with endoluminal-radial OCT (LightLab Imaging) with regard to possible encrustation or crystalline sedimentation. The resolution of OCT was 20 μm. The pullback mode of the endoluminal radial OCT allowed the documentation in 6 μm sequences. Results The median indwelling time was 100 days (19–27 days; n =12 female and n =2 male patients). Firstly, the external encrustation was macroscopically rated in “low”, “medium” and “high”. The macroscopic and the extraluminal OCT results were correlated. With the help of endoluminal OCT, the dimension of intraluminal encrustation could be expressed as a percentage relating to the reference catheter. The luminal reduction caused by encrustation is significant higher at the proximal end of the pigtail. An encrustation at the distal end of the pigtail was only present when there was also an encrustation at the proximal end. Only 2 stents showed an encrustation in the middle part. Conclusion OCT made it possible to detect the encrustation of DJ catheters and express the degree of encrustation quantitatively. The encrustation started at the proximal side and seemed to expand antegrade. Further studies have to be carried out in order to answer the question if an encrustation expands from intra- to extraluminal or vice versa. With the help of OCT, the effect of surface modification of the implanted material could be examined in order to reduce encrustation.

Three-dimensional bipolar voltage map demonstrating electrical activity of a single muscle bundle along the cavotricuspid isthmus

Ablation of the cavotricupsid isthmus (CTI) for the prevention of atrial flutter has traditionally been guided anatomically (1). Recently, an atrial electrogram (EGM) voltage-guided approach was described (2,3). It has been hypothesized that muscle bundles in the CTI are predominantly responsible for conduction through this area, and targeted ablation of those muscle bundles is an efficient and effective means to achieve bidirectional conduction block across the CTI. The muscle bundles can be identified by the highest-amplitude local atrial bipolar EGM recorded along any given ‘line’ between the tricuspid annulus and the inferior vena cava. A voltage map of the CTI bipolar atrial EGM was generated with a 4 mm, steerable irrigated-tip ablation catheter (Cool Path; St Jude Medical Inc, USA) during CTI-dependent atrial flutter (cycle length 243 ms) using a three-dimensional mapping system (NavX; St Jude Medical Inc). Figure 1 shows a caudal left anterior oblique view of the three-dimensional bipolar voltage map. A discrete line of high voltages was seen, demonstrating electrical activity of a single muscle bundle along the CTI. Figure 1) Three-dimensional bipolar voltage map (caudal left anterior oblique veiw). A discrete line of high voltages (purple colour, arrows) is seen, demonstrating electrical activity of a single muscle bundle along the cavotricuspid isthmus. The voltages corresponding ... In voltage maps, the voltages corresponding to the colour codes are indicated on the colour bar. Voltages higher than 1.8 mV (set arbitrarily) are shown in purple. The lowest voltages are shown in red. In the present voltage map, the region of the His potential was indicated by red dots. A duodecapolar catheter was in the right atrium, the ablation catheter was in the inferior vena cava and a reference catheter was in the coronary sinus. Visualization of the high-voltage area of the CTI with endocardial voltage mapping supports the muscle bundle hypothesis and helps with the understanding of the voltage-guided ablation approach for CTI-dependent atrial flutter.

The influence of preconditioning on metabolic changes in the pig liver before, during, and after warm liver ischemia measured by microdialysis

Ischemia-reperfusion injury induced by the Pringle maneuver is a well-known problem after liver surgery. The aim of this study was to monitor metabolic changes in the pig liver during warm ischemia and the following reperfusion preceded by ischemic preconditioning (IPC). Eight Landrace pigs underwent laparotomy. Two microdialysis catheters were inserted in the liver, one in the left lobe and another in the right lobe. A reference catheter was inserted in the right biceps femoris muscle. Microdialysis samples were collected every 30 min during the study. After 2 h of baseline measurement, IPC was performed by subjecting pigs to 10 min of ischemia, followed by 10 min of reperfusion. Total ischemia for 60 min was followed by 3 h of reperfusion. The samples were analyzed for glucose, lactate, pyruvate, and glycerol. Blood samples were drawn three times to determine standard liver parameters. All parameters remained stable during baseline. Glycerol and glucose levels increased significantly during ischemia, followed by a decrease from the start of reperfusion. During the ischemic period, lactate levels increased significantly and decreased during reperfusion. The lactate-pyruvate ratio increased significantly during ischemia and decreased rapidly during reperfusion. Only minor changes were observed in standard liver parameters. The present study demonstrated profound metabolic changes before, during, and after warm liver ischemia under the influence of IPC. Compared with a similar study without IPC, the metabolic changes seem to be unaffected by preconditioning.

Metabolic Changes in the Pigliver During Warm Ischemia and Reperfusion Measured by Microdialysis

AimPortal triad clamping can cause ischemia–reperfusion injury. The aim of the study was to monitor metabolic changes by microdialysis before, during, and after warm ischemia in the pigliver. Material and MethodsEight pigs underwent laparotomy followed by ischemia by Pringle’s maneuver. One microdialysis catheter was placed in each of four liver lobes. A reference catheter was placed in a muscle. Microdialysis samples were collected at intervals of 30 min starting 2 h before 1 h of total ischemia followed by 3 h of reperfusion. Glucose, lactate, pyruvate, and glycerol concentrations were measured. Blood samples were drawn for determination of alanine aminotransferase, alkaline phosphatase, and bilirubin together with total leukocytes and prothrombin time. ResultsAll parameters were stable during the baseline period. During the ischemic period, lactate levels increased significantly (P < 0.05) followed by a rapid decrease after reperfusion. A transient increase was observed for glucose and glycerol. Pyruvate showed a slight increase from the time of ischemia. The lactate–pyruvate ratio increased rapidly after initiating ischemia and decreased immediately after reperfusion. A slight increase in transaminase levels was observed. ConclusionsDuring and after warm ischemia, there were profound metabolic changes in the pigliver observed with an increase in lactate, glucose, glycerol, and the lactate–pyruvate ratio. There were no differences between the four liver lobes, indicating the piglivers homogeneity.

Is Early Detection of Anastomotic Leakage Possible by Intraperitoneal Microdialysis and Intraperitoneal Cytokines After Anterior Resection of the Rectum for Cancer?

This prospective study assessed methods of detecting intraperitoneal ischemia and inflammatory response in patients with and without postoperative complications after anterior resection of the rectum. In 23 patients operated on with anterior resection of the rectum for rectal carcinoma, intraperitoneal lactate, pyruvate, and glucose levels were monitored postoperatively for six days by using microdialysis with catheters applied in two locations: intraperitoneally near the anastomosis, and in the central abdominal cavity. A reference catheter was placed subcutaneously in the pectoral region. Cytokines, interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha, were measured in intraperitoneal fluid by means of a pelvic drain for two postoperative days. The intraperitoneal lactate/pyruvate ratio near the anastomosis was higher on postoperative Day 5 (P = 0.029) and Day 6 (P = 0.009) in patients with clinical anastomotic leakage (n = 7) compared with patients without leakage (n = 16). The intraperitoneal levels of IL-6 (P = 0.002; P = 0.012, respectively) and IL-10 (P = 0.002; P = 0.041, respectively) were higher on postoperative Days 1 and 2 in the leakage group, and TNF-alpha was higher in the leakage group on Day 1 (P = 0.011). In-hospital clinical anastomotic leakage was diagnosed on median Day 6, and leakage after hospital discharge on median Day 20. The intraperitoneal lactate/pyruvate ratio and cytokines, IL-6, IL-10, and TNF-alpha, were increased in patients who developed symptomatic anastomotic leakage before clinical symptoms were evident.

Mass spectrometry and scanning electron microscopy study of silicone tunneled dialysis catheter integrity after an exposure of 15 days to 60% ethanol solution

Anti-infectious lock is an emerging therapeutic option for preventing and/or controlling catheter-associated infection. Ethanol has widespread bactericidal activity, limited side effects, and low risk of inducing antimicrobial resistance. However, concerns have been raised about ethanol-induced catheter structural degradation. In this study, silicone catheters were immersed at 37 degrees C in three different solvents: 0.9% sodium chloride, 60% ethanol, and 95% ethanol for 4 h, 15 days and 15 days after a first storage of 4 h. Scanning electron microscopy (magnification 1000-20 000 times) of the inner surface of the catheter revealed no damage to the lumen surfaces of catheters immersed in 95% ethanol for 15 days compared with the reference catheter. Gas chromatography/mass spectrometry (GC/MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis of the storage solutions revealed a significant release of polydimethylsiloxanes having a number of dimethylsiloxane units lower than 30 in the 95% ethanol solution and a structure highly consistent with a cyclic structure. Most release occurred within the first 4 h of exposure. In contrast, there was no difference in the small amounts of silicone released in 0.9% sodium chloride as reference and 60% ethanol solution, whatever the exposure time. These results should allow the development of clinical trials to assess the efficacy of the 60% ethanol lock technique in preventing or controlling the infectious complications of silicone dialysis catheters.

Metabolic Manipulation of Glioblastoma in Vivo by Retrograde Microdialysis of L-2, 4 Diaminobutyric Acid (DAB)

To study the metabolic effects in vivo of L-2, 4 diaminobutyric acid (DAB) administered by retrograde microdialysis in glioblastoma and to evaluate the feasibility of the technique. In 10 patients with glioblastoma, a stereotactic biopsy was performed followed by implantation of microdialysis catheters. One or two catheters were implanted in tumor tissue and two reference catheters were implanted in normal brain tissue and subcutaneous abdominal tissue, respectively. Tumor catheters were perfused with 80 or 120 mmol/l DAB and reference catheters were perfused with a Ringer solution, all with a flow rate of 2.0 microl/min. Treatment was given for at mean 9.1 (5-19) days. The treatment was well tolerated by the patients with the exception of two patients in whom a transient brain edema appeared. No complications related to the technique were encountered. During treatment, an increase in the extracellular amino acids alanine, glycine, glutamate, aspartate, serine, threonine, and taurine was found demonstrating a significant influence on the intracellular pool of free amino acids induced by DAB. No change in glucose metabolism or glycerol was evident. The metabolism in normal brain was unaffected during treatment. Retrograde microdialysis is a feasible method for intracerebral administration of drugs to tumor tissue in patients with glioblastoma. We found it possible to deliver DAB to glioblastoma tumors in fully mobilized patients and to assess the metabolic effects induced by the treatment. The changes in extracellular amino acids were in concordance to what was expected from in vitro studies. Elevation of glutamate and taurine may be regarded as markers for an induced cellular toxicity while the unchanged level of glycerol may indicate no direct effects on phospholipase activity and membrane phospholipid composition. The effects were restricted to the tumor compartment. Although an improved survival could possibly be suspected no dramatic effect on outcome could be detected. However, the series was small and, most probably, the time for treatment was too short.

Relationship between intra-abdominal and intrarectal pressure in the proctometrogram.

During normal defaecation the intrarectal pressure increases but, in the absence of a reference catheter in the pelvis, the contribution of abdominal straining and rectal contraction to this rise is unclear. Anorectal manometry was performed in ten consecutive women with no gastrointestinal symptoms in an attempt to measure intrapelvic pressure using a catheter in the bladder. During filling the mean (s.e.m.) rectal pressure increased from 2(1) to 18(4) cmH2O. The mean(s.e.m.) intravesical pressure remained unchanged at 2(1) cmH2O. Evacuation of the rectal balloon produced an increase in mean (s.e.m.) intrarectal pressure from 18(4) (end-filling pressure) to 68(15) cmH2O. The mean (s.e.m.) intravesical pressure increased from 2(1) to 51(18) cmH2O. The true intrarectal pressure (intrarectal minus intravesical) did not rise during defaecation. The rise in intrarectal pressure during rectal evacuation occurs by increased intrapelvic pressure alone.

Novel Technique to Facilitate Defibrillator Lead Implantation via Cephalic Vein Cutdown by Means of a Reference Catheter and a Specially Designed Long Sheath

The cephalic vein is recommended as the access route for an implantable cardioverter defibrillator lead to avoid complications associated with subclavian vein puncture; however, cephalic vein cutdown is not necessarily preferred, mainly because of procedural complexity. To facilitate cephalic vein cutdown, we have devised the following method. An 8 Fr catheter is placed in the cephalic vein over a guidewire inserted percutaneously from the left peripheral cephalic vein. The catheter, which is palpable beneath the skin prior to incision, indicates the location of the cephalic vein, facilitating its isolation. A specially designed 9 Fr tear‐away sheath‐dilator unit is used to place leads. With its long‐tapered and curved tip, the unit is easy to insert, even when the cephalic vein is stenotic or tortuous. The 30‐cm‐long sheath reaches the right atrium, and thus the lead is advanced directly to the right atrium without risk of vascular injury. This technique may be feasible in the majority of patients and can even be used by inexperienced implanters.

Novel Technique to Facilitate Defibrilla-tor Lead Implantation via Cephalic Vein Cutdown by Means of a Reference Catheter and a Specially Designed LongSheath

Novel Technique to Facilitate Defibrilla-tor Lead Implantation via Cephalic Vein Cutdown by Means of a Reference Catheter and a Specially Designed LongSheath

Results of intraperitoneal microdialysis depend on the location of the catheter

Jansson K, Strand I, Redler B, Magnuson A, Ungerstedt U, Norgren L. Results of intraperitoneal microdialysis depend on the location of the catheter. 2004; 64: 63-70.Background and Objective: Intraperitoneal microdialysis was recently described as a method for early detection of visceral ischemia. The method seems safe and accurate. The intra-abdominal catheter used may imply variations in results depending on the location of the catheter. The aim of the study was to investigate possible differences in metabolic parameters obtained depending on various locations of the intra-abdominal catheter, compared with using the subcutaneous reference catheter. Method: After right-sided hemicolectomy in 12 patients, three catheters were placed and fixed intraperitoneally: one at the anastomosis, one in the omentum and one embedded between the small intestinal loops. A subcutaneous catheter placed in the pectoral region was used as reference. Analyses of lactate/pyruvate ratio and glucose and glycerol levels were done during a period of 45 hours postoperatively. Results: Lactate/pyruvate ratio decreased numerically at all three intraperitoneal locations during the study while the subcutaneous lactate/pyruvate ratio increased slightly. Significant differences between intraperitoneal and subcutaneous locations were found as well as differences between the three intraperitoneal locations. Highest values of the lactate/pyruvate ratio were found at the anastomosis, while the widest range was found at the small intestine. Subcutaneous glucose levels were lower while glycerol levels were higher compared with intraperitoneal values. Conclusions: In evaluating postoperative metabolism, intraperitoneal microdialysis is influenced by the location of the microdialysis catheter. The same pattern is, however, recorded over time. The juxta-anastomotic region and the small intestinal loop area seem to be the most reasonable locations for measurements.

The metabolism of the diabetic foot: in vivo investigation with microdialysis.

Many amputations might be delayed or prevented by more effective clinical supervision of the diabetic foot ulcer. The aim of this study was to measure the local metabolism on the edge of a diabetic ulcer and compare it to healthy subcutaneous tissue. In 5 non-fasting diabetic patients, we inserted a microdialysis catheter into the edge of a diabetic ulcer and a reference catheter into healthy abdominal subcutaneous tissue, and recorded the local concentrations of glucose, lactate and glycerol during rest. The concentrations of glucose in the ulcers were 7.8 mM (SEM 1.9) and in the reference tissue 10.6 mM (SEM 1.8) (p = 0.4). The concentrations of lactate were 2.9 mM (SEM 0.7) and 2.1 mM (SEM 0.7) (p = 0.2), while those of glycerol were 290 microM (SEM 84) vs 98 microM (SEM 7.2) (p = 0.002). This study shows that microdialysis can detect differences in dialysate concentrations of metabolites in diabetic ulcers and a reference tissue, providing valuable information concerning metabolites in the diabetic foot ulcer. Future studies should combine the technique with measurements of local blood flow.

Chronic performance of a new implantable pressure and oxygen saturation sensor in canines

Background: Pressure (Pr) and oxygen saturation (SvO2) trends measured from the right ventricle (RV) might help physicians make therapeutic decisions for heart failure (HF) patients. Prior implantable hemodynamic monitor (IHM) studies used pressure sensors alone or pressure and SvO2 sensors contained on separate leads. A recent IHM study reported satisfactory performance of RVPr sensors placed near the RV outflow tract (RVOT) in patients followed >1year. Other prior studies of implanted SvO2 sensors reported biocompatibility problems (BioP) when the sensors were placed deeper in the RV. We hypothesized that BioP could be reduced and satisfactory performance of both Pr and SvO2 could be achieved using a new dual-sensor with both Pr and SvO2 combined (PrO2) and implanted in the RVOT. Methods: The newly designed PrO2 sensors were implanted in 6 canines and compared to standard catheter-based measurements at implant and approx. 1, 2, 3, 6, 9 and 12 months. Under anesthesia, a reference SvO2 catheter was placed in the pulmonary artery and a reference Pr catheter was placed in the right ventricle. To change SvO2, helium inhalations were done lasting ≤3 minutes (repeated at least 3 times). To change Pr levels, IV Dobutamine was infused in stepwise doses from 2.8 to 11.0 μg/kg/min. Evaluation of the data was done by regression of the PrO2 sensor values versus the reference catheter values. Continuous ambulatory trend data from the IHM were also used to check for occurrences of BioP between catheterizations by comparing individual optical signal levels from the SvO2 sensor to expected levels. Results: There were no sensor, lead or IHM device technical failures as of 1 year. One SvO2 sensor exhibited early BioP, was re-implanted at 2 months, showed degraded performance 2–8 months, then accurate 9- and 12-month invasive performance. A second sensor showed partially degraded performance from BioP at 9 months. Pooled results (through 9 months) from 36 of the 42 invasive tests (including all sensors) are summarized below. Original sensor calibrations were used over the entire year. Small offsets (INTCPT) in Pr and SvO2 were present at initial tests, were stable throughout follow-up and were not corrected. Data are Mean±SD. Conclusions: SvO2 from all 6 implanted PrO2 sensors performed well at 1-year invasive testing while 2 of the sensors showed evidence of BioP at various times in the chronic and/or invasive data. In all sensors implanted, Pr worked well throughout the year of follow-up. A new combined PrO2 sensor is feasible, maintains long term accuracy of the Pr sensor function and shows improved SvO2 sensor biocompatibility when placed in the RVOT. Tabled 1R2S.E.E.SLOPEINTCPTSvO20.97±0.041.80±0.330.91±0.027.33±12.99RV Pulse Pressure0.92±0.131.13±1.000.77±0.143.86±1.87 Open table in a new tab

Intraperitoneal microdialysis (IPM): a new technique for monitoring intestinal ischemia studied in a porcine model.

Acute mesenteric thrombosis, vascular complications of intestinal transplantation, sepsis, and multiple organ failure are all associated with intestinal ischemia. To improve the outcome of these patients, better monitoring devices are needed. A new technique, intraperitoneal microdialysis (IPM), was evaluated for detection of intestinal ischemia in a porcine model, with the intention of evaluating the technique for future use on humans. Fourteen pigs divided into two studies were used. In a total ischemia study a microdialysis catheter was placed intraperitoneally and the superior mesenteric artery was occluded for 1 h 40 min. In a local ischemia study, the arcus vessels supplying a 30-cm long small bowel segment were occluded for 3 h 20 min. One IPM catheter was placed next to the ischemic area and another IPM catheter 10 cm caudally as an intraperitoneal reference. In both studies reference catheters were placed subcutaneously. Glucose, lactate, pyruvate, and glycerol were analyzed every 20 min. In both studies vessel occlusion resulted in decreased glucose and increased lactate, glycerol, and lactate/pyruvate ratio. Significant changes were reached after 60 min of ischemia in most analytes, whereas the values from the reference catheter were stable. Our conclusion is that intestinal ischemia is detectable with IPM based on the analysis of well-documented markers of ischemia (increased lactate/pyruvate ratio) and cell membrane damage (elevated glycerol levels). It allows semi-continuous monitoring of the intestines with a minimally invasive procedure, which we believe will be possible to apply in human routine clinical use.

System and method for electrode localization using ultrasound

The present invention is a device localization system that uses one or more ultrasound reference catheters to establish a fixed three-dimensional coordinate system within a patient's heart using principles of triangulation. The coordinate system is represented graphically in three-dimensions on a video monitor and aids the clinician in guiding other medical devices, which are provided with ultrasound transducers, through the body to locations at which they are needed to perform clinical procedures. In one embodiment of a system according to the present invention, the system is used in the heart to help the physician guide mapping catheters for measuring electrical activity, and ablation catheters for ablating selected regions of cardiac tissue, to desired locations within the heart.

Radiofrequency ablation of cardiac arrhythmias using a three-dimensional real-time position management and mapping system.

A recently developed three-dimensional real-time position management system (RPM) uses an ultrasound ranging technique that enables multiple distance measurements between two reference catheters and a mapping catheter each equipped with ultrasound transducers. In addition to three-dimensional representation of the catheters and ablation sites it displays real-time movements of catheters (including the tip and shaft). A recently released version of the system enables additional geometry reconstruction of the heart chamber and activation mapping. This study included 21 patients (mean age 59 +/- 14.5 years) referred for radiofrequency catheter ablation of various arrhythmias. Geometry was reconstructed by tracing the endocardial contour of the respective heart chambers. Global and local color coded activation maps were constructed to confirm the nature of arrhythmia and to guide ablation. Spontaneous or induced arrhythmias were typical atrial flutter (n = 8), atypical atrial flutter (n = 3), atrioventricular nodal reentrant tachycardia (n = 3), atrial tachycardia (n = 2), atrial fibrillation (n = 2), ventricular tachycardia (n = 2), and Wolff-Parkinson-White syndrome (n = 1). Geometry reconstruction and mapping of arrhythmias were possible in 20 of 21 patients. RPM-guided radiofrequency ablation was successful in 19 (95%) of 20 patients. Due to difficulties in steering the RPM mapping/ablation catheter, in 6 (28%) successfully mapped patients, radiofrequency ablation was performed using another catheter. In one patient, the RPM-guided map was inconclusive and in another patient, ablation failed due to multiple reentrant circuits. No complications were observed. In conclusion, the new RPM system enables geometry reconstruction and three-dimensional positioning of the ablation catheters, reconstruction of the activation maps, marking of anatomic structures and reproducible tracking of multiple ablation sites. The system could be used to guide radiofrequency ablation of atrial and ventricular arrhythmias.