Right atrial thrombus formation associated with central venous catheters utilization in hemodialysis patients

Objective To report five patients on hemodialysis via an indwelling central venous catheter who developed a thrombus located exclusively on the right atrial wall opposing the emptying site of the superior vena cava and to determine the possible cause of this location.Design Transthoracic echocardiography was performed in four of the patients as work-up for suspected endocarditis or pulmonary embolism and in one patient for syncope evaluation. The right atrial clots were confirmed in all the patients by transesophageal echocardiography.Design and setting General intensive care unit of a university hospital, tertiary referral center.Patients Five patients with end-stage chronic renal failure on hemodialysis via subclavian or internal jugular vein catheter.Interventions Three of these patients underwent surgical thrombectomy, and two others were medically treated.Measurements and results The clots were 2–4 cm in length and three of them were infected. Two of the three surgically treated patients and one of the two medically treated patients died. All the patients had the catheter tip in the right atrium, in two of them the bent catheter rubbed the atrial endocardium, and in all the cases the clot was located on the atrial free wall facing the superior vena cava emptying.Conclusions We postulate that the mechanism of thrombus formation at this location is related to friction of the catheter on the atrial endocardium, and therefore positioning the distal segment of the central venous catheters in the right atrium should be avoided.     

Exit-site location does not influence peritoneal catheter infection rate

Peritoneal catheter infections are a cause of peritonitis, catheter loss, and permanent transfer of continuous ambulatory peritoneal dialysis (CAPD) patients to hemodialysis. Risk factors for catheter infections have not been delineated. We investigated the location of the peritoneal exit-site location as a risk factor for catheter infection and loss. There was no relationship between catheter infection rates and exit location. Catheters exiting on the beltline had a median infection rate of 0.5 episodes/year, as opposed to 1.2 episodes/year for catheters exiting above the beltline and 0.9 episodes/year for catheters exiting below the beltline (ns). The percentage of catheters that became infected and required removal was the same for catheters exiting above, below, or on the beltline. Although we recommend avoiding the beltline for patient comfort, exit-site location is not an important determinant of infection rates or catheter outcome.     

Unusual Cause of Recurrent Syncope in a Child

A 5‐year‐old boy with an unremarkable past medical and family history presented with recurrent syncope precipitated by physical activity. Electrocardiogram performed in the emergency room after one of his episodes revealed atrial flutter. He had a structurally normal heart. Exercise stress test revealed atrial fibrillation with rapid ventricular response immediately on commencement of running. Atrial fibrillation subsequently organized into atrial flutter with variable ventricular response followed by spontaneous conversion to sinus rhythm. This case highlights the use of exercise stress test in a preschool child to elicit an unusual cause of syncope.     

长期双腔留置导管在血液透析患者中的应用

摘要 目的 观察长期双腔留置导管(permanent dual lumen catheter, PDLC)在维持性血液透析患者中作为血管通路的效果及常见并发症。 方法 我科自2005年12月至2007年2月共行PDLC留置术13例，男7例，女6例，平均年龄63.31±12.26(39~90)岁，均通过颈内静脉留置，术后拍摄胸片确定导管位置。以尿素清除指数Kt/V为透析效果的客观评价指标。 结果 使用美国Quinton公司生产带涤纶套双腔留置导管经颈内静脉入路，12例经右侧，1例经左侧，平均使用7.8（2～14）个月。常见的并发症有：导管内血栓形成或血流不畅2例14次，发生率4.58例次/1000导管日；感染1例2次，0.65例次/1000导管日；出血1例3次。13例患者的平均Kt/V值1.27±0.22。 结论 对于自身血管条件差无法建立内瘘的患者和心功能较差不能耐受内瘘手术的患者来说，PDLC不失为一种有效的替代方法，可以达到较为满意的透析效果。如果处理得当，并发症也比较少。     

Radiofrequency Catheter Ablation of Atrial Flutter That Elicits Inappropriate Implantable Cardioverter Defibrillator Discharge

The case of a patient with recurrent VT and an ICD is reported. After appropriate device discharges, the patient experienced 40 episodes of inappropriate shock therapy due to atrial arrhythmias confirmed as type I atrial flutter. Since programmed stimulation could reliably initiate atrial flutter, catheter ablation was performed. During delivery of RF current, atrial flutter terminated and was no longer inducible. The patient had no further inappropriate device discharges during 12 months of follow-up. In patients with ICDs suffering from recurrences of atrial flutter leading to inappropriate shock therapy, RF catheter ablation is an effective and curative approach.     

Studies on digitalis. VI. The effect of heparin on serum protein binding of digitoxin and digoxin.

The aim of the present study was to investigate the nature of the previously reported changes in the serum protein binding of digitoxin and digoxin in uremic patients under treatment with hemodialysis. Kinetic studies on protein binding during hemodialysis showed that the free fraction of digitoxin rose from 2.6% to 6.9% after 5 min of hemodialysis and remained elevated during the dialyzing period. Free digoxin rose from hemodialysis and remained elevated during the dialyzing period. Free digoxin rose from 78.3% to 87.1% during the same period. In vitro hemodialysis experiments showed that such changes occurred only in vivo. Injection of heparin (5,000 IU) to control subjects produced similar kinetic changes in the protein binding of digitoxin and digoxin. Free fatty acids changed in the same way. These results indicate that the heparin-induced release of free fatty acids causes displacement of digitoxin and digoxin from their albumin-binding sites. Patients on hemodialysis have lower serum levels of digitoxin and cardioactive metabolites (mean, 8.9 ng/ml) than control patients (mean, 16.7 ng/ml) (p less than 0.005) on similar doses (mean, 0.085 mg/day). They should be maintained on the same digotoxin doses as uremic and control patients, but serum digitoxin levels should be adjusted to 10 to 15 ng/ml in hemodialysis patients compared to 15 to 25 ng/ml in uremic patients and in patients with normal renal function.     

规律性尿激酶溶栓治疗对长期颈内静脉留置双腔导管功能的影响

目的 探讨规律性尿激酶溶栓治疗对长期颈内静脉留置双腔导管功能的影响.方法 将26例颈内静脉双腔导管留置时间大于3个月的维持性血液透析患者分为观察组和对照组,每组13例,观察组在常规导管护理的同时,每月定期1次尿激酶溶栓治疗,对照组采用常规导管护理方法.观察比较两组透析前抽吸导管通畅情况,透析中血流速度、回路静脉压、血流不畅需导管干预的例数及因栓塞更换导管的例数.结果 观察组透析前抽吸导管通畅情况、透析中血流速度、回路静脉压、血流不畅需导管干预的例数及因栓塞更换导管的例数与对照组比较差异有统计学意义(P<0.05).结论 规律性尿激酶溶栓治疗,可有效地维持长期颈内静脉留置双腔导管的功能,延长导管使用时间,提高透析效率,是一种安全有效的治疗手段.     

经食道心房快速起搏终止心房扑动的方法学及效果评价

目的对32例心房扑动(房扑)发作患者采用经食道心房快速起搏方法进行终止,对其方法及疗效进行评价。方法经鼻插入食道电极,深度至食道电图能记录到最大心房电位处。使用20~35V输出电压、10 ms脉宽进行心房S1S1 250~600次/min逐级递增快速起搏,每次递增50次/min,每次起搏时间2~5 s,至房扑终止。结果 32例患者共36次房扑,其中32次经食道心房快速起搏终止,转复成功率89%,典型房扑成功率100%(27/27次),非典型房扑成功率56%(5/9次)。平均操作时间(38±15)min,7次(22%)直接转为窦性心律,25次(78%)先经历房颤然后转为窦性心律。术中快速起搏时多数患者出现不同程度的胸骨后烧灼感,均能良好耐受,无血栓栓塞及其他不良反应发生。结论经食道心房快速起搏终止心房扑动是一种快速、安全、简便、有效的方法,可作为房扑转复的首选治疗。     

Mechanical Ablation of Concealed Left Lateral Bypass Tract

A 50-yaer-old man with hypertension had been treated for supraventricular tachycardia with several medications for nine years. In 1990, he was started on amiodarone but a year later he developed side effects causing discontinuation of amiodarone. Because of his recurrent episodes of palpitations associated with near syncope, chest pain and shortness of breath, he underwent an electrophysiology study in 1992 that showed orthodromic AVRT with the presence of a concealed left-sided accessory bypass tract. Scheduled for radiofrequency ablation the following day, after catheters were placed and during mapping of the lateralmitral annulus, his tachycardia stopped abruptly without further inducability. Isoproterenol infusion during atrial and ventricular stimulation also failed to induce his original tachycardia. A year later, the patient presented with palpitations that felt different than his previous experiences. Work-up at that point only revealed a parasystolic focus on a 24-hour ECG monitoring without any form of supraventricular tachycardia. This represents a very unusual case by which the left lateral accessory pathway was mechanically ablated with catheter manipulation. This led to the disappearance of the orthodromic tachycardia that was easily induced before due to the activity of his parasytolic focus. The latter continued for the following four years but the patient has had no recurrences of his tachycardia.     

Paroxysmal atrial fibrillation: ectopic atrial activity and prevalence of severely symptomatic patients

Catheter ablation is a promising approach in severely symptomatic patients with paroxysmal atrial fibrillation (PAF). Until this time it has only been performed in highly selected patients with weekly episodes and frequent premature atrial contractions (PACs). The aim of the present study was to estimate the prevalence of severely symptomatic patients with PAF and to evaluate the significance of PACs. The files of 7,447 consecutive patients were screened and 1,357 PAF patients identified. Holter recordings were performed in 108 patients with >/=2 spontaneous AF episodes. Despite antiarrhythmic treatment, 6.5% (1.8-11.1%) had a history of weekly PAF episodes. 29.2% of patients and 10% of healthy, age-matched controls had more than 700 PACs. The number of PACs was inversely related to the reported numbers of previous episodes and directly related to age and size of left atrium. We estimate that about 6.5% of patients with PAF are severely symptomatic and might benefit from catheter ablation. Our data suggest that the number of PACs should not be used as a selection criterion for catheter ablation. Frequent PACs are seen in a substantial proportion of elderly healthy individuals.     

Management of atrial arrhythmias secondary to severe congenital heart disease with the Atrioverter

An atrial defibrillator was implanted in a patient with congenitally corrected transposition of the great arteries, associated cardiac abnormalities, and persistent atrial arrhythmias. During a 15-month follow-up, 14 of 20 spontaneous episodes of his arrhythmias were successfully treated with the device. Two of these episodes were converted to sinus rhythm during ambulatory use of the device. Successful use of the device required implantation of a third defibrillation lead in the persistent left-sided superior caval vein and rigid control of congestive heart failure. An atrial defibrillator may be a valid treatment option in patients with congenital heart disease crippled by atrial fibrillation.     

Inserting Tunnelled Hemodialysis Catheters Using Elective Guidewire Exchange From Nontunnelled Catheters: Is There a Greater Risk of Infection When Compared Too New-Site Replacement?

The objective of this article was to evaluate bacteremia outcomes and survival rates when using guidewire exchange to place tunnelled hemodialysis catheter (THDC) compared to a new-site replacement. Retrospectively identified all patients who received a THDC between 01/01/2000 and 01/01/2007. Excluded any THDC having received antibiotic line locks or tunnelled to tunnelled exchange. This left 408 THDC placed in 329 patients: 46 guidewire exchange, 362 new-site replacement. Bacteremia rate from the new-site insertion group was 3.0 per 1,000 catheter days, the guidewire exchange group demonstrated a rate of 2.8 per 1,000 catheter days. Local infection rates did not differ between groups at 1.2 per 1,000 catheters days. The actuarial survival rates using Kaplan-Meier survival analysis demonstrated no difference between the two groups. The placing of tunnelled cuffed hemodialysis catheters to replace temporary catheters using a guidewire exchange did not contribute to further episodes of sepsis and has the advantage of preserving venous access and minimizing invasive procedures for the patient.     

Delayed Cardiac Perforation by Defibrillator Lead Placed in the Right Ventricular Outflow Tract Resulting in Massive Pericardial Effusion

A 76‐year‐old man received a dual‐chamber implantable cardioverter defibrillator (ICD), with the defibrillator lead positioned within the right ventricular outflow tract. The lead parameters at the time of implantation were satisfactory and the postprocedure chest X‐ray showed the leads were in place. The patient was cardioverted from atrial fibrillation during defibrillation threshold testing and commenced on anticoagulation immediately. One month post implantation, he experienced multiple ventricular tachycardia episodes all successfully treated with antitachycardia pacing and shocks by his ICD, but he fell and hit his chest against a hard surface during one of these attacks. He developed a massive pericardial effusion and computed tomography confirmed cardiac perforation by the defibrillator lead. Pericardiocentesis was performed and the defibrillator lead replaced with a different model positioned at the right ventricular apex. The patient made an uneventful recovery. The management and avoidance of delayed cardiac perforation by transvenous leads were discussed.     

Atrial Flutter Ablation using a Technique for Detection of Conduction Block within the Posterior Isthmus

Catheter ablation orientated on the induction of a functional intraatrial block within the posterior isthmus of the tricuspid annulus has been shown to effectively abolish atrial flutter. In order to improve and simplify the current technique, a strategy based on an electrode catheter for combined right atrial and coronary sinus mapping and stimulation was explored prospectively. Twenty-four consecutive patients referred for catheter ablation of recurrent type I atrial flutter were included. A steerable 7 Fr catheter (Medtronic/Cardiorhythm) composed of two segments with 20 electrodes was used for right atrial and coronary sinus activation mapping and stimulation. Multiple steering mechanisms allowing intubation and positioning of the distal part within the coronary sinus were incorporated into the device. Adequate positioning of the mapping catheter was achieved solely via a transfemoral approach in all patients after 7.7 +/- 4.6 minutes, providing stable electrogram recordings during the entire ablation procedure. Radiofrequency current ablation (16.3 +/- 9.6 pulses) caused a significant bidirectional increase of the mean intraatrial conduction times via the posterior isthmus irrespective to the stimulation interval. Significant changes of intraatrial conduction properties were induced during ablation in 22 of 24 patients (bidirectional block: n = 18, unidirectional block: n = 3, conduction delay: n = 1, unchanged conduction: n = 2). Following ablation atrial flutter was noninducible in all patients. Twenty-two of 24 patients (92%) remained free of atrial flutter episodes during a follow-up of 12.5 +/- 5.7 months. Two of six patients without a bidirectional conduction block had a recurrence of atrial flutter. Atrial flutter ablation guided by the induction of an intraatrial conduction block can be effectively performed with this novel strategy for combined mapping of the posterior tricuspid isthmus, including coronary sinus and right atrial free wall. This transfemoral approach has a high accuracy with respect to the detection of radiofrequency current-induced changes of intraatrial conduction patterns.     

Ablation of a Left-Sided Free-Wall Accessory Pathway by Percutaneous Catheter Application of Radiofrequency Current in a Patient with the Wolff-Parkinson-White Syndrome

A case is presented of a 20-year-old woman with a history of three episodes of syncope within the last 4 years, which was caused by a rapid ventricular response to atrial fibrillation via a left-sided posterior accessory pathway. A variety of antiarrhythmic agents had failed to control the arrhythmia. Using a novel dual catheter approach, with one catheter in the coronary sinus and an adjacent catheter in the left ventricle close to the mitral annulus, accessory pathway conduction was successfully interrupted by two radio-frequency current applications between the tip electrodes of the two catheters. During follow-up, 12-lead electrocardiograms have been normal and the patient has been asymptomatic.     

Continuous ambulatory peritoneal dialysis and renal transplantation: a ten-year experience in a single center.

OBJECTIVE: To assess whether a renal graft outcome is dependent on the modality of dialysis prior to transplantation and to assess risk of peritonitis and catheter-related problems posttransplantation. DESIGN: Retrospect analysis of the outcome of a first cadaveric renal transplantation from hemodialysis (HD) and CAPD patients over a ten-year period. PATIENTS: Out of a total of 905 renal transplants over a ten-year period, 699 were first grafts; 500 of these (241 on CAPD, 259 on hemodialysis) were analyzed while the remaining (incomplete data, predialysis, pediatric) were assessed for graft and patient survival only. MAIN OUTCOME: Graft and patient survival cases were identical in the two groups (five-year graft survival: CAPD 67%, hemodialysis 66%; five-year patient survival: CAPD 88%, hemodialysis 87%). CAPD posttransplant was necessary in 37 patients, while 10 developed peritonitis mostly related to CAPD use and responded to appropriate therapy. Routine catheter removal posttransplant was undertaken between 8 and 12 weeks. CONCLUSION: Excellent graft and patient survival is achieved independent of the modality of dialysis prior to transplantation. Peritoneal dialysis can be used postgrafting, but there is a risk of peritonitis, which can be successfully managed with antibiotics and catheter removal. Great care is needed in executing the dialysis and catheter care after transplantation.     

Electrical Atrial Remodeling Assessed by Monophasic Action Potential and Atrial Refractoriness in Patients with Structural Heart Disease

The present study was performed to assess the effect of induced atrial fibrillation (AF) on atrial monophasic action potentials (MAPs) and atrial refractory period (ERP) in patients with structural heart disease. An electrode MAP catheter was placed in the right atrium to continuously measure atrial potential duration (APD₉₀) in 13 patients (coronary artery disease, 10 patients; dilated cardiomyopathy, 2 patients; hypertrophic cardiomyopathy, 1 patient) without spontaneous AF episodes. AF was induced by rapid atrial stimulation (300–1500/min). If sinus rhythm returned within 10 minutes, AF was reinduced. The atrial ERP was measured during atrial pacing at a basic cycle length of 550 ms before AF induction and after its conversion. Results: The mean atrial ERP and the atrial APD₉₀ before AF was 242 ± 34 ms and 256 ± 23 ms, respectively. ERP and APD_go shortening was observed after 3 minutes of AF. After 11 ± 0.5 min (10 min 20 s-13 min 10 s) of AF, ERP and APD₉₀ reached their minimal values of 72%± 13% and 71%± 10% of baseline, respectively. ERP and APD₉₀ returned to their initial values within 10 minutes after conversion of AF. A tendency toward longer duration of consecutive AF episodes and facilitation of their induction was observed. Conclusion: The present study confirms that short episodes of AF modify the electrophysiological properties of the atria in humans. In patients with structural heart disease, induced atrial fibrillation shortens the atrial ERP as well as the atrial APD₉₀. The changes were reversible within 10 minutes after arrhythmia termination.     

Further Observations of "Linking" of Atrial Excitation During Clinical Atrial Fibrillation

The objective of this article was to look for evidence of nonrandom behavior during atrial fibrillation hy examining long (> 15 minutes) recordings. We have previously reported transient "linking" of atrial activation during atrial fibrillation, and showed that activation was not entirely randotn. Over the few episodes of linking seen during 1 minute, activation directions apparently repeated, indicating a possible anatomical or physiological constraint. In the present study, we examined atrial fibrillation over longer time periods to see if this constancy of direction was stable. Endocardial recordings were made from 12 patients with atrial fibrillation using a catheter with three orthogonal bipoies, aHowing measurements of local activation directions in three dimensions. The direction was calculated using Pipberger's half-area method, and episodes of transient linking were identified. An average direction for each episode of linking was calculated and plotted in two dimensions using spherical coordinates (altitude and azimuth). In addition, the nature of initiation and termination of linking was examined. Of the twelve patients, 611 episodes of linking (range 1 to 169 per patient, mean 51) were identified. The episodes for most patients clustered closely in direction. In contrast, directions measured for all activations (i.e., linked and not linked) filled up the entire available range. Linking in most cases subjectively appeared to initiate and terminate suddenly. The results indicate that the local anatomy, pathology, or physiology of the atrium has a strong constraining effect on the electrical activations occurring during atrial fibrillation, and revises our perception of activation during atrial fibrillation as "random." The demonstration that local properties greatly influence conduction during fibrillation has important implications for ablation or pacing therapy.     

Transhepatic venous approach to permanent pacemaker placement in a patient with limited central venous access

The end-stage renal disease population poses a challenge for obtaining venous access required for life-saving invasive cardiac procedures. In this case report, we describe an adult patient with end-stage renal disease in whom the hepatic vein was the only available access to implant a single-lead permanent cardiac pacemaker. A 63-year-old male with endstage renal disease on maintenance hemodialysis and permanent atrial fibrillation/atrial flutter presented with symptomatic bradycardia. Imaging studies revealed all traditional central venous access sites to be occluded/non-accessible. With the assistance of vascular interventional radiology, a trans-hepatic venous catheter was placed. This was then used to place a right ventricular pacing lead with close attention to numerous technical aspects. The procedure was completed successfully with placement of a single-lead permanent cardiac pacemaker.     

Toward Optimizing a Preshaped Catheter and System Parameters to Achieve Single Lead DDD Pacing

P wave electrogram amplitudes and atrial stimulation thresholds were determined in eight Hanford miniature swine using a preshaped catheter with an "S" curve in the SVC, and a major lobe in the atrium to enhance electrode contact with the atrial wall. The catheter was designed for pacing and sensing in the DDD mode. P wave amplitudes were also ascertained with two commercially available VDD leads and compared to the data from the experimental catheters. The preshaped catheter used two 6-mm² platinum iridium atrial electrodes with a 7-mm separation. Both atrial electrodes are on the same side of the catheter, facing outward on the major atrial lobe formed in the catheter. The P wave amplitudes were tested only in the differential bipolar configuration. For the eight preshaped catheters, the mean was 6.6 ± 3.8 mV while for the conventional leads it was 2.9 ± 1.6 mV. The mean atrial stimulation thresholds ranged from 1.1 t 0.2 V to 2.3 ± 1.2 V, with still lower thresholds of 0.9-1.3 V when using the parallel unipolar atrial electrode configuration, in which both parts of the bipolar atrial electrode are configured as a unipolar electrode. The data suggest that bipolar stimulation may be effective if sequential reverse polarity pulses are used to achieve cathodal stimulation from each electrode of the bipolar pair, on a beat-to-beat basis. (PACE 1997; 20[Pt. I]:1354-1358)