Intracardiac Electrocardiogram Research Articles

Expert consensus on the whole-course management of implantable venous access port in the upper arm of cancer patients (2024 edition)

As one of a major public health issue in China, the number of new cases and deaths of malignant tumors has been climbing year by year. Implantable venous access port (IVAP) is used as a safe infusion route in the treatment of malignant tumor patients such as infusion of antitumor drugs and intravenous nutrition. With the widespread application of ultrasound-guided Sedinger puncture techniques and intracardiac electrocardiogram positioning technology, IVAP in the upper arm has been recognized by the majority of medical personnel and cancer patients due to its advantages of hiding scars and completely avoiding the risk of hemothorax and pneumothorax. In order to standardize the clinical application of IVAP via the upper arm approach in cancer patients, improve the success rate of implantation, reduce complications and improve patient satisfaction, the Breast Cancer Expert Committee of the National Cancer Quality Control Center consulted guidelines and the latest evidence-based evidences and established the expert consensus on the whole-course management of implantable venous access port in the upper arm of cancer patients through literature research and expert discussions, in order to provide reference for the standard application of IVAP in the upper arm. The consensus mainly introduces the indications, contraindications, preoperative evaluation, implantation site, operation procedure, utilization and maintenance, complications and management, medical staff training and patient education of IVAP in the upper arm, in order to provide reference for clinical staff.

Usefulness of the intracardiac electrocardiogram recorded using central venous catheters on P-wave magnification

BackgroundThe detection of atrial electrical activity is extremely valuable in recognizing complex cardiac arrhythmias. However, P-wave detection on a surface electrocardiogram (S-ECG) can sometimes be challenging. The intracardiac electrocardiogram (IC-ECG), recorded by a central venous catheter loaded with saline solution, has proven to be a safe and effective method for amplifying atrial electrical activity. We aim to compare the P-wave amplitude recorded in the S-ECG and the IC-ECG in different venous accesses, catheters, heart rhythms, and atrial dimensions. MethodsWe compared the P wave amplitude obtained by the IC-ECG and the S-ECG recordings from cardiac intensive care unit patients. ResultsIn 109 nonconsecutive patients, a total of 166 IC-ECG were collected. The median amplitude of the P wave was 0.1 (0.083–0.3) mV in the S-ECG and 0.4 (0.25–2.4) mV in the IC-ECG; p < 0.001. This difference remained significant regardless of the patient's heart rhythm, left atrial dimension, and catheter or vascular access used. ConclusionThe IC-ECG acquired using central venous catheters significantly increases atrial electrical activity signals. This technique might help identify complex cardiac arrhythmias.

Effectiveness and safety of intracardiac electrocardiogram guidance for epicutaneo-cava catheters via the lower extremity in preterm infants: a retrospective study

IntroductionIn recent years, intracardiac electrocardiogram (IC-ECG) technology has been widely used for epicutaneo-cava catheter (ECC) placement and has shown many potential advantages. However, evidence about the quantitative changes, effectiveness, and safety of IC-ECG for lower extremity ECC is sparse. This study aimed to explore the quantitative changes in IC-ECG for lower extremity ECC and determine its effectiveness and safety.MethodsA retrospective study was conducted on 303 premature infants who underwent successful IC-ECG-guided lower extremity ECC placement between January 2019 and December 2021. All patients underwent chest X-ray postoperatively to verify the position of the catheter tip. The amplitudes of the surface electrocardiogram and IC-ECG QRS waves and the difference between the two amplitudes were measured. The effectiveness (matching rate between IC-ECG and chest X-ray) and safety (incidence of catheter-related complications) of IC-ECG for lower extremity ECC were evaluated.ResultsThe matching rate between IC-ECG and chest X-ray was 95.0%. When the catheter tip was optimally positioned, the QRS amplitude of the IC-ECG was 0.85 ± 0.56 mv higher than that of the surface electrocardiogram. The overall incidence of catheter-related complications was 10.6%. The actual ECC insertion length was associated with a noticeably increased risk of catheter-related complications.ConclusionsThis study suggests that IC-ECG is an effective and safe method by observing the dynamic changes in both QRS complexes and P wave to locate the tip of lower extremity ECC in preterm infants. Our findings would facilitate the application of IC-ECG for ECC localization.

Animal study on left bundle branch current of injury and anatomic location of leads in His-purkinje conduction system pacing

Objective: Explore the relationship between tip of the left bundle branch pacing lead and anatomic location of left bundle branch as well as the mechanism of left bundle branch current of injury. To clarify the clinical value of left bundle branch current of injury during operation. Methods: The pacing leads were implanted in the hearts of two living swines. Intraoperative electrophysiological study confirmed that the left bundle branch or only the deep left ventricular septum was captured at low output. Immediately after operation, the gross specimen of swine hearts was stained with iodine to observe the gross distribution of His-purkinje conduction system on the left ventricular endocardium and its relationship with the leads. Subsequently, the swine hearts were fixed with formalin solution, and the pacing leads were removed after the positions were marked. The swine hearts were then sectioned and stained with Masson and Goldner trichrome, and the relationship between the anatomic location of the conduction system and the tip of the lead was observed under a light microscope. Results: After iodine staining of the specimen, the His-purkinje conduction system was observed with the naked eye in a net-like distribution, and the lead tip was screwed deeply and fixed in the left bundle branch area of the left ventricular subendocardium in the ventricular septum. Masson and Goldner trichrome staining showed that left bundle branch pacing lead directly passed through the left bundle branch when there was left bundle branch potential with left bundle branch current of injury, while it was not directly contact the left bundle branch when there was left bundle branch potential without left bundle branch current of injury. Conclusion: The left bundle branch current of injury observed on intracardiac electrocardiogram during His-purkinje conduction system pacing suggests that the pacing lead directly contacted the conduction bundle or its branches, therefore, the captured threshold was relatively low. Left bundle branch current of injury can be used as an important anatomic and electrophysiological evidence of left bundle branch capture.

Paradigm shift of catheter ablation of atypical atrioventricular nodal tachycardia: 3D mapping-based ablation of exits of slow pathway

Abstract Background In current practice, the ablation target of atypical atrioventricular nodal tachycardia (AVNRT) is the earliest atrial activation site in the coronary sinus (CS) or conventional slow pathway (SP) region. Objectives The purpose of this study was to map the site of earliest retrograde atrial activation using electroanatomic 3D mapping during atypical AVNRT and to evaluate successful ablation sites. Methods Forty-two patients with a total of 49 AVNRTs (slow/fast 30; fast/slow 15; slow/slow 4) underwent EP study and ablation. Among them there were 14 patients (10 women, 60±19 y/o) in whom 19 atypical AVNRT (fast/slow 15; slow/slow 4) were induced. Results The intracardiac electrocardiograms or 3D mapping of the exit site during tachycardia revealed that 7 patients had exit sites solely inside the CS (left inferior extension=LIE), 3 solely in the right postero-septal tricuspid annulus (TA) (right inferior extension=RIE), and 4 had both LIE and RIE exits. The distance from the CS ostium to LIE exits was 14±6 mm. RIE exits were located on the TA posterior to the CS ostium (between 5 and 6 o’clock in the LAO projection). Ablation targeting these exits or traditional SP succeeded in long term elimination of AVNRT in 13 of the 14 patients (93%). There were no complications. Conclusions Catheter ablation targeting the exit sites of LIE or RIE mapped at the CS or TA holds promise as an effective and safe alternative approach to the current targets of ablation for atypical AVNRT cases.Distribution of exit sites during atypicthe circuit of atypical AVNRT：the exit s

Electrocardiography of Atrioventricular Block.

Delayed atrioventricular (AV) conduction most commonly occurs in the AV node, resulting from AH prolongation on an intracardiac electrocardiogram and PR prolongation on a surface electrocardiogram. AV conduction may be blocked in a 2:1 manner, with a normal PR interval and wide QRS suggesting infranodal disease, whereas a prolonged PR interval and narrow QRS are more suggestive of AV nodal disease. Block within the His is suspected when there is 2:1 AV block with normal PR and QRS intervals. Complete heart block occurs when the atrial rhythm is totally independent of a junctional or lower escape rhythm.

Paradigm Shift for Catheter Ablation of Atypical Atrioventricular Nodal Re-Entrant Tachycardia: 3-Dimensional Mapping–Based Ablation

BackgroundIn current practice, the ablation target of atypical atrioventricular nodal re-entrant tachycardia (AVNRT) is the earliest atrial activation site in the coronary sinus (CS) or conventional slow pathway region. ObjectivesThe purposes of this study were to map the site of earliest retrograde atrial activation using electroanatomic three-dimensional mapping during atypical AVNRT and to evaluate successful ablation sites. MethodsA total of 42 patients with a total of 49 AVNRTs (slow/fast: 30; fast/slow: 15; slow/slow: 4) underwent electrophysiological study and ablation. Among them there were 14 patients (10 women; 60 ± 19 years of age) in whom 19 atypical AVNRT (fast/slow: 15; slow/slow: 4) were induced. ResultsThe intracardiac electrocardiograms or three-dimensional mapping of the exit site during tachycardia revealed that 7 patients had exit sites solely inside the CS (left inferior extension [LIE]), 3 solely in the right postero-septal tricuspid annulus (TA; right inferior extension [RIE]), and 4 had both LIE and RIE exits. The distance from the CS ostium to LIE exits was 14 ± 6 mm. RIE exits were located on the TA posterior to the CS ostium (between 5 and 6 o’clock in the left anterior oblique projection). Ablation targeting these exits or conventional slow pathway succeeded in long-term elimination of AVNRT in 13 of the 14 patients (93%). There were no complications. ConclusionsCatheter ablation targeting the exit sites of LIE or RIE mapped at the CS or TA holds promise as an effective and safe alternative approach to the current targets of ablation for atypical AVNRT cases.

PO-04-024 THE SMALL HOURS OF THE NIGHT; VENTRICULAR PACING INHIBITION IN A HIS BUNDLE PACEMAKER

Physiologic pacing is a promising alternative to conventional pacing with increasing utilization. We present a novel cause of pacing inhibition discovered after AV node ablation in a permanent His bundle pacing lead. Highlight a rare case of repetitive ventricular pacing inhibition due to internal validation and storage of an intracardiac electrocardiogram on the ventricular channel that occurred in a His bundle pacemaker. N/A An 85-year-old female with paroxysmal AF on flecainide, chronic RBBB, interstitial lung disease, SSS s/p dual chamber pacemaker with a His lead 4 years prior in anticipation of AV node ablation was admitted with highly symptomatic AF with RVR. With failure of both rhythm and rate control, she ultimately underwent successful AV node ablation. Overnight, telemetry showed AS-VP except for hourly events of a single sinus P wave without a following pacing spike or ventricular complex (Figure 1). Atrial and His lead parameters remained normal, and the device was programmed DDDR, not AAIR<-> DDDR. There was no farfield sensing of atrial or His signals on the ventricular channel. The pacemaker manufacturer (Medtronic), noted non-programmable intracardiac electrogram internal validation and storage that can occur every hour plus 30 seconds, but no sooner. During this storage process, ventricular pacing inhibition of a single cycle may occur due to residual electrical disturbance on the ventricular channel from turning on and off EGM collection, unrelated to conventional oversensing of intracardiac signals. The EGM collection must follow an atrial sensed event, consistent with telemetry findings. Thus far it has only been observed with Advisa pacemaker models, which utilizes sensitivity decay based on a ventricular sensed event. Once identified, the RV sensitivity is recommended to be decreased, in this case adjusted from 0.9mV to 2.8mV. This change prevented this phenomenon from re-occurring and the patient was doing well at follow-up 6 months later. This may be more common in His bundle pacing due to smaller R waves, higher V pacing burden, and use of this later model pacemaker. There is a broad differential for failure to pace, especially in a His bundle pacing lead. This case highlights a unique cause of hourly ventricular pacing inhibition, specific to this pacemaker model which may be frequently used in physiologic pacing, unrelated to traditional His lead oversensing.

Echocardiography- versus intracardiac electrocardiogram-based optimization of cardiac resynchronization therapy: A systematic review.

This systematic review aimed to evaluate the performance of echocardiography-based programming in comparison with the intracardiac electrocardiogram (IEGM)-based method for the optimization of cardiac resynchronization therapy (CRT). A literature review was conducted using digital databases to systematically identify the studies reporting CRT optimization through echocardiography compared with IEGM. Detailed patient-level study characteristics including the type of study, sample size, therapy, the New York Heart Classification (NYHA) status, lead placement, and other parameters were abstracted. Finally, postprogramming outcomes were extracted for each article. In a total of 11 studies, 919 patients were recruited for the final analysis. Overall, 692 (75.29%) were males. The mean duration of the QRS complex in our study population ranged from 145.2± 21.8ms to 183 ± 19.9ms. There was an equal improvement in the NYHA class between the two methods while the left ventricular ejection fraction (LVEF) demonstrated an improvement by IEGM. Many studies supported IEGM to increase the 6-minute walk test and left ventricular outflow tract velocity time interval (LVOT VTI) when compared to echocardiography. The mean time for echocardiography-based optimization was 60.15 min while that of IEGM-based optimization was 6.65 min. IEGM is an alternative method for CRT optimization in improving the NYHA class, LVEF, and LVOT VTI, and is less time-consuming when compared to the echocardiography-based methods.

Direct observation of a stable spiral wave reentry in ventricles of a whole human heart using optical mapping for voltage and calcium.

From the studies of Gordon Moe in the 1960s, functional reentry has been investigated as a mechanism for tachycardia and fibrillation; however, it was not until 1990 that optical mapping (OM) experiments using sheep hearts verified the existence of reentrant spiral waves.1 Eventually, it was shown that electromechanical 3-dimensional vortex filaments drive cardiac fibrillation.2 To date, only multiple complex and short-lived reentrant waves have been recorded using OM on human ventricles.3 The presence of single spiral waves in human ventricles has only been demonstrated using low-resolution intracardiac electrocardiograms (ECGs).

In vivo and ex vivo electrophysiological study of the mouse heart to characterize the cardiac conduction system, including atrial and ventricular vulnerability.

The mouse is a common and cost-effective animal model for basic research, and the number of genetically engineered mouse models with cardiac phenotype is increasing. In vivo electrophysiological study in mice is similar to that performed in humans. It is indispensable for acquiring intracardiac electrocardiogram recordings and determining baseline cardiac cycle intervals. Furthermore, the use of programmed electrical stimulation enables determination of parameters such as sinoatrial conduction time, sinus node recovery time, atrioventricular-nodal conduction properties, Wenckebach periodicity, refractory periods and arrhythmia vulnerability. This protocol describes specific procedures for determining these parameters that were adapted from analogous human protocols for use in mice. We include details of ex vivo electrophysiological study, which provides detailed insights into intrinsic cardiac electrophysiology without external influences from humoral and neural factors. In addition, we describe a heart preparation with intact innervation by the vagus nerve that can be used as an ex vivo model for vagal control of the cardiac conduction system. Data acquisition for in vivo and ex vivo electrophysiological study takes ~1 h per mouse, depending on the number of stimulation protocols applied during the procedure. The technique yields highly reliable results and can be used for phenotyping of cardiac disease models, elucidating disease mechanisms and confirming functional improvements in gene therapy approaches as well as for drug and toxicity testing.

Clinical valuation of ST changes in a group of patients with ventricular arrhythmias: The inSighT Study.

BackgroundThe inSighT study was designed to determine the prevalence of ischemic changes as recorded by implantable cardioverter–defibrillator (ICD) ST deviations in intracardiac electrocardiograms (EGM) over the 24 h preceding malignant ventricular arrhythmias (VT/VF).MethodsThe study enrolled patients with known coronary artery disease (CAD) or high risk of future development of CAD implanted with an ICD equipped with an ST monitoring feature (Ellipse™/Fortify Assura™, St. Jude Medical). Device session records were collected at each in‐clinic follow‐up. EGM ST levels of the beats over the 15 minutes prior to VT/VF events were compared using a t test with those from a baseline period of 23–24 h prior to the VT/VF event. All events with p < .05 were visually inspected to confirm they were evaluable; additional criteria for exclusion from further analysis included inappropriate therapy, aberrant conduction, and occurrence of VT/VF within 24h prior to the current event.ResultsThe study enrolled 481 ICD patients (64 ± 11 years, 83% male) in 14 countries and followed them for 15±5 months. A total of 165 confirmed VT/VF episodes were observed, of which 71 events (in 56 patients, 34% of all patients with VT/VF) were preceded by significant (p < .05) ST‐segment changes unrelated to known non‐ischemic causes. None of the analyzed demographic and clinical factors proved to be associated with greater odds of presenting with ST‐segment changes prior to VT/VF episode.ConclusionIn this exploratory study, characteristic ST‐segment changes, likely representative of ischemic events, were observed in 34% of all patients with VT/VF episodes.

Electrocardiography of Atrioventricular Block.

Delayed atrioventricular (AV) conduction most commonly occurs in the AV node, resulting from AH prolongation on an intracardiac electrocardiogram and PR prolongation on a surface electrocardiogram. AV conduction may be blocked in a 2:1 manner, with a normal PR interval and wide QRS suggesting infranodal disease, whereas a prolonged PR interval and narrow QRS are more suggestive of AV nodal disease. Block within the His is suspected when there is 2:1 AV block with normal PR and QRS intervals. Complete heart block occurs when the atrial rhythm is totally independent of a junctional or lower escape rhythm.

Arrhythmogenesis in the aged heart following ischaemia-reperfusion: role of transient receptor potential vanilloid 4.

Cardiomyocyte Ca2+ homoeostasis is altered with ageing and predisposes the heart to Ca2+ intolerance and arrhythmia. Transient receptor potential vanilloid 4 (TRPV4) is an osmotically activated cation channel with expression in cardiomyocytes of the aged heart. The objective of this study was to examine the role of TRPV4 in Ca2+ handling and arrhythmogenesis following ischaemia-reperfusion (I/R), a pathological scenario associated with osmotic stress. Cardiomyocyte membrane potential was monitored prior to and following I/R in Langendorff-perfused hearts of Aged (19-28 months) male and female C57BL/6 mice ± TRPV4 inhibition (1 μM HC067047, HC). Diastolic resting membrane potential was similar between Aged and Aged HC at baseline, but following I/R Aged exhibited depolarized diastolic membrane potential vs. Aged HC. The effects of TRPV4 on cardiomyocyte Ca2+ signalling following I/R were examined in isolated hearts of Aged cardiac-specific GCaMP6f mice (±HC) using high-speed confocal fluorescence microscopy, with cardiomyocytes of Aged exhibiting an increased incidence of pro-arrhythmic Ca2+ signalling vs. Aged HC. In the isolated cell environment, cardiomyocytes of Aged responded to sustained hypoosmotic stress (250mOsm) with an increase in Ca2+ transient amplitude (fluo-4) and higher incidence of pro-arrhythmic diastolic Ca2+ signals vs. Aged HC. Intracardiac electrocardiogram measurements in isolated hearts following I/R revealed an increased arrhythmia incidence, an accelerated time to ventricular arrhythmia, and increased arrhythmia score in Aged vs. Aged HC. Aged exhibited depolarized resting membrane potential, increased pro-arrhythmic diastolic Ca2+ signalling, and greater incidence of arrhythmia when compared with Young (3-5 months). TRPV4 contributes to pro-arrhythmic cardiomyocyte Ca2+ signalling, electrophysiological abnormalities, and ventricular arrhythmia in the aged mouse heart.

Diagnosis of atrial fibrillation in heart failure patients with implantable cardioverter defibrillator or cardiac resynchronisation therapy.

IntroductionImplantable cardioverter defibrillators register various types of arrhythmias. Thus they can be exploited to better identify patients with atrial fibrillation episodes and increase the proportion of patients who may benefit from implementation of pharmacological prophylaxis of thromboembolic events, most of which are asymptomatic. The aim of the study was to assess of the frequency, symptoms and predisposing factors for the occurrence of atrial fibrillation episodes in patients with an implanted implantable cardioverter defibrillator (ICD) and cardiac resynchronisation therapy with defibrillator (CRT-D) based on the analysis of intracardiac electrocardiograms (EGM/IEGM) records.Material and methodsThe study included 174 consecutive outpatients with heart failure, sinus rhythm and an implanted cardioverter defibrillator and cardiac resynchronisation therapy with defibrillator. Follow-up visits with analysis of IEGM records occurred every 3 months. During a mean follow-up of 20 months, 901 visits were carried out. One hundred forty-seven patients had at least 1 year of follow-up.ResultsAtrial fibrillation episodes in the study group occurred in 54 (31.0%) patients and 71.4% were asymptomatic. Predisposing factors were: history of paroxysmal atrial fibrillation (37.0% vs. 13.3%, p < 0.001), atrioventricular conduction abnormalities (42.6% vs. 20.0%, p = 0.002), intraventricular conduction abnormalities (59.3% vs. 40.8%, p = 0.02) and more severe mitral regurgitation (7.4% vs. 0.8%, p = 0.04). Chronic renal disease was a risk factor for death in the study group. No stroke occurred during the study.ConclusionsEpisodes of paroxysmal atrial fibrillation in patients with systolic heart failure and implanted cardioverter-defibrillator systems are quite common. The majority of the episodes recorded in the study were asymptomatic.

Idiopathic right ventricular arrhythmias requiring additional ablation from the left-sided outflow tract: ECG characteristics and efficacy of an anatomical approach.

Despite the characteristic electrocardiogram (ECG) findings of early activation during ventricular tachyarrhythmias (VAs) and/or excellent pacemapping in the right ventricular outflow tract (RVOT), some VAs may require additional, left-sided ablation for a cure. This study included five patients with idiopathic VAs whose QRS morphologies were highly suggestive of an RVOT origin. The ECG characteristics and intracardiac electrocardiograms during catheter ablation were assessed. In all patients, the clinical VAs had an LBBB QRS morphology and inferior axis with a precordial R/S transition through leads V3-V5, and negative components in lead I. The earliest activation during the VAs (local electrogram-QRS interval = -34 ± 6.8 ms) and excellent pacemapping were obtained at the posterior portion of the RVOT just beneath the pulmonary valve. However, ablation at those sites failed, and the QRS morphology of the VAs changed. During left-sided OT mapping, the earliest activation was found at sites just contralateral to the initially ablated sites of the RVOT (junction of the left and right coronary cusps = 2, left coronary cusp = 3). In spite of the late activation time and poor pacemapping scores, catheter ablation at those sites cured the VAs. Those successful sites were also near the transitional zone from the great cardiac vein to the anterior interventricular vein (GCV-AIV). Some VAs, highly suggestive of having RVOT origins, require catheter ablation in the left-sided OT near the initially ablated RVOT site. Those VAs have the same ECG characteristics and might have intramural origins in the superobasal LV surrounded by the RVOT, LVOT, and GCV-AIV.

Abstract WP258: Effectiveness of Detection Asymptomatic Episodes of Atrial Fibrillation in Heart Failure Patients With Cardioverter Defibrillator

Introduction: Implantable cardioverter defibrillators due to the possibility of continuous recording of intracardiac electrograms can detect episodes of atrial fibrillation. In practice, this allows better identification of patients with asymptomatic AF episodes, thus increasing the proportion of patients who may benefit from pharmacological prophylaxis of thromboembolic events, particularly stroke. Hypothesis: If intracardiac electrogram analysis should be part of each visit carried out in patients with implantable cardioverter defibrillator, how much of detected episodes of atrial fibrillation is asymptomatic. Methods: The study included 174 consecutive outpatient cases with heart failure, sinus rhythm and implanted Cardioverter Defibrillator and Cardiac Resynchronisation Therapy with Defibrillator. Control visits with analysis intracardiac electrograms records occurred every three months. Each AF episode stored in the device’s memory lasting at least 30 seconds was considered an episode of atrial fibrillation. A symptomatic episode was considered when arrhythmia led to ICD shock, heart deterioration, collapse or fainting, palpitations, weakness, chest pain or shortness of breath accompanied by a feeling of irregular heartbeat. During mean follow-up of 20 months, 901 visits were carried out. 147 patients had at least one year of follow-up. Results: Atrial fibrillation (AF) episodes in the study occurred in 54 (31.0%) patients. Of the 241 atrial fibrillation episodes recorded in the device’s memory, 71.4% were asymptomatic. There was no statistically significant difference in the incidence of new episodes of atrial fibrillation (P = 0.384) in the study group with a history of stroke or transient ischemic episodes during follow-up. However, asymptomatic AF episodes were more common in stroke patients (P = 0.0074). In the time of observation in the whole group of patients there were no new strokes and transient ischemic attack. Conclusion: In conclusion, detection of asymptomatic atrial fibrillation episodes based on intracardiac electrocardiogram records is effective method. In the study group, such episodes were up 71.4% of all newly detected AF episodes.

Surface measurement, intracardiac electrocardiogram and tracheal bifurcation techniques for locating the catheter tips of totally implantable venous access port

BackgroundThe purpose of our study is to compare the reliability and consistency of three commonly used techniques, which are surface measurement, intracardiac electrocardiogram (IECG) and tracheal bifurcation methods in measuring the tip location of totally implantable venous access port (TIVAP) in the same patient. MethodsThe thirty-five patients scheduled for implantation of TIVAP were included and right subclavian vein was selected for venous access. We used surface measurement method (Group L) to estimate the length and position of catheter before catheterization, and then we used IECG method (Group E) to confirm the position of catheter during catheterization and after catheterization used tracheal bifurcation method by CT (Group T) for measurement. The differences of catheter length measured by three methods were compared by non-parametric Kruskal–Wallis test. Intraclass correlation coefficient (ICC) was used to evaluate the reliability of three methods and Bland-Altman chart was used to evaluate consistency. ResultsThere are no difference in the length of TIVAP catheter between L and T groups (P > 0.05), but they have significant differences comparing with E group (P < 0.05). The three positioning methods have a good consistency (ICC = 0.886, P < 0.05).Through linear regression analysis, the regression equation are: catheter length (mm) = 77.32 + 0.66 × height (cm), 36.25 + 0.81 × height (cm) and 68.82 + 0.70 × height (cm). The distances from catheter tip to the junction of superior vena cava and right atrium measured by IECG (Group E) was closer to the target value. ConclusionsAll three methods can be used to measure the length of TIVAP catheter, and IECG method is the most accurate. And similar to most studies, returning the catheter 20 mm after positioning can avoid catheter entering the right atrium, but we found that 10 mm is a sufficient length to achieve this.

Effect of Ischemic Preconditioning and Postconditioning on Exosome-Rich Fraction microRNA Levels, in Relation with Electrophysiological Parameters and Ventricular Arrhythmia in Experimental Closed-Chest Reperfused Myocardial Infarction.

We investigated the antiarrhythmic effects of ischemic preconditioning (IPC) and postconditioning (PostC) by intracardiac electrocardiogram (ECG) and measured circulating microRNAs (miRs) that are related to cardiac conduction. Domestic pigs underwent 90-min. percutaneous occlusion of the mid left anterior coronary artery, followed by reperfusion. The animals were divided into three groups: acute myocardial infarction (AMI, n = 7), ischemic preconditioning-acute myocardial infarction (IPC-AMI) (n = 9), or AMI-PostC (n = 5). IPC was induced by three 5-min. episodes of repetitive ischemia/reperfusion cycles (rI/R) before AMI. PostC was induced by six 30-s rI/R immediately after induction of reperfusion 90 min after occlusion. Before the angiographic procedure, a NOGA endocardial mapping catheter was placed again the distal anterior ventricular endocardium to record the intracardiac electrogram (R-amplitude, ST-Elevation, ST-area under the curve (AUC), QRS width, and corrected QT time (QTc)) during the entire procedure. An arrhythmia score was calculated. Cardiac MRI was performed after one-month. IPC led to significantly lower ST-elevation, heart rate, and arrhythmia score during ischemia. PostC induced a rapid recovery of R-amplitude, decrease in QTc, and lower arrhythmia score during reperfusion. Slightly higher levels of miR-26 and miR-133 were observed in AMI compared to groups IPC-AMI and AMI-PostC. Significantly lower levels of miR-1, miR-208, and miR-328 were measured in the AMI-PostC group as compared to animals in group AMI and IPC-AMI. The arrhythmia score was not significantly associated with miRNA plasma levels. Cardiac MRI showed significantly smaller infarct size in the IPC-AMI group when compared to the AMI and AMI-PostC groups. Thus, IPC led to better left ventricular ejection fraction at one-month and it exerted antiarrhythmic effects during ischemia, whereas PostC exhibited antiarrhythmic properties after reperfusion, with significant downregulaton of ischemia-related miRNAs.

Research progress of PICC tip positioning method

This review introduced the best position of the tip of PICC, and sorted out the methods of confirming tips′ position before/through/after catheters′ insertion, which including measuring through landmark of body, intracardiac electrocardiogram positioning technique, electromagnetic induction, B ultrasound, digital subtraction angiography, radiograph and coughing. Every method played their unique role in clinical. We gathered these methods to wish to give some suggestions for clinicals. Key words: Catheterization, peripheral; Central venous catheter; Ectopic; Position