Effective ablation of atrial tachycardia with an epicardial circuit-insights from endocardial scars sites: a case study

A previous study reported primary macroreentrant atrial tachycardia (AT) in the left atrium (LA), including the epicardial circuit on a left atrial anterior wall (LAAW) scar, without any prior cardiac intervention (Miyazawa et al. in J Cardiovasc Electrophysiol 2019; 30: 263-264). However, determining the target for terminating macroreentrant ATs is challenging. The mapping revealed a centrifugal pattern but did not fully elucidate the AT circuit. The reentrant mechanism of these ATs was confirmed using entrainment pacing. The earliest excitation site (EES) was traditionally selected as the ablation site, typically located in healthy tissue. However, our two cases provide new insights into AT termination, including the epicardial bridge across the endocardial LAAW scar, using minimum ablation points, without the need to ablate the healthy EES.

Endocardial Fibroelastosis Resection: When it Works and When it Does Not

Endocardial fibroelastosis (EFE) is a thickening of the endocardial layer by accumulation of collagen and elastic fibers. Endothelial to mesenchymal transformation is proposed to be the underlying mechanism of formation. Although EFE can occur in both right and left ventricles, this article will focus on management of left ventricular EFE. Through its fibrous, nonelastic manifestation EFE restricts the myocardium leading to diastolic and systolic ventricular dysfunction and prevents ventricular growth in neonates and infants. The presence of EFE may be a marker for underlying myocardial fibrosis as well. The extent of EFE within the left ventricular cavity can be variable ranging from patchy to confluent distribution. Similarly the depth of penetration and degree of infiltration into myocardium can be variable. The management of EFE is controversial, although resection of EFE has been reported as part of the staged ventricular recruitment therapy. Following resection, EFE recurs and infiltrates the myocardium after primary resection. Herein we review the current experience with EFE resection.

Ambient circulation surrounding an ablation catheter tip affects ablation lesion characteristics

INTRODUCTION

The association between ambient circulating environments (CEs) and ablation lesions has been largely underexplored.

METHODS

Viable bovine myocardium was placed in a saline bath in an ex vivo endocardial model. Radiofrequency (RF) ablation was performed using three different ablation catheters: 3.5 mm open irrigated (OI), 4, and 8 mm. Variable flow rates of surrounding bath fluids were applied to simulate standard flow, high flow, and no flow. For in vivo epicardial ablation, 24 rats underwent a single OI ablation and performed with circulating saline (30 ml/min; n = 12), versus those immersed in saline without circulation (n = 12).

RESULTS

High flow reduced ablation lesion volumes for all three catheters. In no-flow endocardial CE, both 4 mm and OI catheters produced smaller lesions compared with standard flow. However, the 8 mm catheter produced the largest lesions in a no-flow CE. Ablation performed in an in vivo model with CE resulted in smaller lesions compared with ablation performed in a no-flow environment. No statistically significant differences in steam pops were found among the groups.

CONCLUSION

A higher endocardial CE flow can decrease RF effectiveness. Cardiac tissue subjected to no endocardial CE flow may also limit RF for 4 mm catheters, but not for OI catheters; these findings may have implications for RF ablation safety and efficacy, especially in the epicardial space without circulating fluid or in the endocardium under varying flow conditions.

Intramyocardial Mapping of Ventricular Arrhythmias via Septal Venous Perforators: Defining the Superior Intraseptal Space

Left ventricular outflow tract arrhythmias that fail endocardial mapping and ablation have traditionally been labeled as originating from the epicardial left ventricular summit. Although these sometimes can be targeted from the epicardial surface of the left ventricular ostium, such approach poses significant technical challenges. A significant proportion of such arrhythmias, however, exhibit intramyocardial origin, demonstrated by mapping intraseptal branches of the anterior interventricular vein, and henceforth defined as the basal superior intraseptal space.

Surgical Ablation of Ventricular Tachycardia

Surgery for ventricular tachycardia (VT) is indicated in patients in whom pharmacotherapy or catheter ablation is ineffective or frequent VT attacks are not suppressed or with frequent activation of implantable cardioverter defibrillator. In ischemic VT, resection of fibrous endocardium combined with encircling cryothermia at the border between the infarcted and normal myocardium is performed. In surgery for VT associated with cardiomyopathy, close collaboration between the physician and surgeon is important and intraoperative mapping using electro-anatomic mapping system is helpful. In VT associated with cardiac tumors, cryothermia of the thinned subepicardial myocardium at the edge of the tumor is recommended in addition to resection of tumors.

Techniques for Catheter Ablation of Idiopathic Ventricular Arrhythmias Originating from the Outflow Tract and Left Ventricular Summit

Idiopathic ventricular arrhythmias (VAs) most commonly originate from the ventricular outflow tracts. Because the anatomy of this region is complex and some of those VA origins are intramural and epicardial, it may sometimes be difficult to locate the site of the VA origin. Meticulous mapping in multiple different locations such as the right and left ventricular outflow tracts, endocardial and epicardial sites, and above and below the aortic and pulmonic valves may be required to achieve successful catheter ablation of those VAs. Special ablation techniques may be considered to improve the outcome of catheter ablation of intramural and epicardial VAs.

[Anatomy of the left ventricle for endocardial ablation]

As with all cardiac interventions, performing left ventricular ablation requires profound knowledge of cardiac anatomy. The aim of this article is to provide an overview of left ventricular anatomy and to characterize complex and clinically relevant structures from an electrophysiologist-centered perspective. In addition to the different access routes, the trabecular network, the left ventricular outflow tract, and the left ventricular conduction system, complex anatomical structures such as the aortomitral continuity and the left ventricular summit are also explained. In addition, this article offers multiple clinical examples that combine ECG, anatomy, and electrophysiologic study.

Malignant Ventricular Tachycardia, Ventricular Wall Ablation, and Orthotopic Heart Transplantation

Described herein are three patients with refractory ventricular tachycardia and one or more unsuccessful ablation procedures finally leading to orthotropic heart transplantation (OHT). The latter procedure allowed examination of the ventricular ablation sites, an unusual opportunity reported previously in few patients (all case reports). The acute ablation lesions are unique, with necrosis of the myocardial fibers adjacent to the endocardium and encircled by layers of extravasated erythrocytes in the deeper myocardial wall. All 3 patients returned to normal activities following the OHT.

Study on the effect of different blood flow velocities of pulmonary vein on endocardial microwave ablation of atrial fibrillation

OBJECTIVE

To cure atrial fibrillation, the maximum ablation depth (⩾ 50∘C) should exceed the myocardial thickness to achieve the effect of transmural ablation. The blood flow of pulmonary vein in the endocardium can cause the change in the myocardial temperature distribution. Therefore, the study investigated the effect of different pulmonary vein blood flow velocities on the endocardial microwave ablation.

METHODS

The finite element model of the endocardial microwave ablation of pulmonary vein was simulated by electromagnetic thermal flow coupling. The ablation power was 30 W and the ablation time was within 30 s. The blood flow in the coupling of fluid mechanics equation and heat transfer equation results in the heat damage. Furthermore, the cause of the different lesion dimensions is the blood flow velocity. The flow velocities were set as 0, 0.02, 0.05, 0.07, 0.12, 0.16, 0.20, 0.25 and 0.30 m/s.

RESULTS

When the flow velocities were 0, 0.02, 0.05, 0.07, 0.12, 0.16, 0.20, 0.25 and 0.30 m/s, the maximum ablation depth were 6.0, 5.56, 5.16, 5.12, 5.04, 5.01, 4.98, 4.96 and 4.94 mm, respectively; the maximum ablation width were 12.52, 9.63, 9.23, 9.16, 9.07, 9.05, 8.94, 8.91, 8.90 mm, respectively; the maximum ablation length were 12.00, 11.61, 8.98, 8.59, 8.37, 8.23, 8.16, 8.06 and 8.04 mm respectively. To achieve transmural ablation, the time was 3, 3, 3, 3, 3, 4, 4, 4, 4 s, respectively when the myocardial thickness was 2 mm; the time was 7, 8, 8, 8, 9, 9, 9, 9, 9 s, respectively when 3 mm; the time was 15, 16, 18, 19, 19, 20, 20, 20, 20 s, respectively when 4 mm.

CONCLUSIONS

When the velocity increases from 0 m/s to 3 m/s, the microwave lesion depth decreases by 1.06 mm. To achieve transmural ablation, when the myocardial thickness is 2 mm, 3 and 4 s should be taken when the velocity is 0-0.12 and 0.120.30 m/s, respectively; when the myocardial thickness is 3 mm, 7, 8 and 9 s should be taken when 0, 0-0.07 and 0.07-0.30 m/s respectively; when the myocardial thickness is 4 mm, 15, 16, 18, 19, 20 s should be taken when 0, 0-0.02, 0.02-0.05, 0.05-0.12, 0.12 m/s-0.30 m/s.

Epicardial versus Endocardial Closure: Is One Better than the Other?

Left atrial appendage occlusion is an evolving technology with demonstrable benefits of stroke prophylaxis in patients with atrial fibrillation unsuitable for anticoagulation. This has resulted in the development of a plethora of transcatheter devices to achieve epicardial exclusion and endocardial occlusion. In this review, the authors summarize the differences in technique, target patient population, outcomes, and complication profiles of endocardial and epicardial techniques.

Left Atrial Appendage Closure: Technical Considerations of Endocardial Closure

Left atrial appendage closure (LAAC) is a safe and effective therapy for the prevention of stroke in patients with nonvalvular atrial fibrillation and high bleeding risk with oral anticoagulants. Multimodality imaging with transesophageal echocardiography and computed tomography angiography to define the anatomy and its implications on endocardial exclusion is becoming increasingly important. The only LAAC device currently approved for clinical use in the United States is the WATCHMAN device. Systematic assessment of the transseptal crossing site, left atrial appendage anatomy, adequate device size selection, and device postdeployment evaluation is essential for the safety and efficacy of the procedure.

Contact Forces Required to Record Monophasic Action Potentials: A Complement to Catheter Contact Force Measurement

OBJECTIVE

The ability to monitor catheter contact force (CF) plays a major role in assessing radiofrequency ablation, impacting lesion size and arrhythmia recurrence, and dictating ablation duration and/or overall patient safety. Our study sought to determine the relative CFs required to elicit reproducible monophasic action potential (MAP) recordings.

METHODS

The study utilized four swine in which: first, median sternotomies were performed and MAPs were collected from seven ventricular locations on the epicardial surface of each heart; and second, a subset of endocardial signals was recorded from a reanimated heart. In these studies, the initial elicitation and then loss of stable MAP waveforms were recorded, as were their associated catheter CFs (n = 371).

RESULTS

Mean CF at the onset of stable MAP recordings was 14.2 ± 2.9 g for epicardial and 16.6 ± 2.5 g for endocardial locations. Across epicardial locations, no significant differences in CF were required to elicit MAPs. Additionally, endocardial and epicardial CFs for MAPs did not significantly differ for respective locations, i.e., right ventricular septum endocardial versus epicardial. In our study, the catheter CFs required to elicit MAPs were within optimal ranges previously reported for eliciting clinically viable radiofrequency ablations.

CONCLUSION

We believe that MAP recordings could complement CF measurements with electrical data, providing additional clinical feedback for physicians performing cardiac ablation.

SIGNIFICANCE

If applied clinically, MAP recordings could potentially improve ablation outcomes in patients with cardiac arrhythmias.

Transcatheter aortic valve replacement (TAVR) leads to an increase in the subendocardial viability ratio assessed by pulse wave analysis

Background

Pulse wave analysis (PWA) is a useful tool for non-invasive assessment of central cardiac measures as subendocardial perfusion (Subendocardial Viability Ratio, SEVR) or contractility (dP/dt_max). The immediate influence of transcatheter aortic valve replacement (TAVR) on these indices has not been investigated yet.

Methods

We prospectively enrolled 40 patients presenting with severe aortic stenosis receiving TAVR. Central pressure curves were derived from radial and carotid sites using PWA up to 2 days before and 7 days after TAVR. Parameters were compared between peripheral measurement sites. Changes in SEVR, dP/dt_max and in indices of vascular stiffness were assessed. Additionally, association of these variables with clinical outcome was evaluated during a 12-month follow-up.

Results

Central waveform parameters were comparable between measurement sites. SEVR, but not dP/dt_max, augmentation Index (AIx) or augmentation pressure height (AGPH) correlated significantly with disease severity reflected by peak transvalvular velocity and mean transvalvular pressure gradient over the aortic valve (V_max, ΔPm) [r = -0.372,p = 0.029 for V_max and r = -0.371,p = 0.021 for ΔPm]. V_max decreased from 4.5m/s (IQR:4.1–5.0) to 2.2m/s (IQR:1.9–2.7), (p<0.001). This resulted in a significant increase in SEVR [135.3%(IQR:115.5–150.8) vs. 140.3%(IQR:123.0–172.5),p = 0.039] and dP/dt_max [666mmHg(IQR:489–891) vs. 927mmHg(IQR:693–1092),p<0.001], and a reduction in AIx [154.8%(IQR:138.3–171.0) vs. 133.5%(IQR:128.3–151.8),p<0.001] and AGPH [34.1%(IQR:26.8–39.0) vs. 25.0%(IQR 21.8–33.7),p = 0.002], confirming the beneficial effects of replacing the stenotic valve. No association of these parameters could be revealed with outcome.

Conclusions

PWA is suitable for assessing coronary microcirculation and contractility mirrored by SEVR and _maxdP/dt in the setting of aortic stenosis. PWA parameters attributed to vascular properties should be interpreted with caution.

Myocardial voltage ratio in arrhythmogenic right ventricular dysplasia/cardiomyopathy

AIMS

This study aimed to analyze the influence of scar distribution between the endocardium and the epicardium in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C).

METHODS

Electroanatomical mapping data were derived from our ARVD/C registry. Myocardial voltage distribution between the endocardium and the epicardium was analyzed in 28 patients (18 men, 49.9 ± 13.0 years) with previous ventricular tachycardia (VT) ablation and complete right ventricular maps.

RESULTS

During the follow-up period of 28 ± 22 months after ablation, 18 of 28 patients (64.3%) remained free from VT recurrence. In univariate analysis, five variables associated with VT recurrence, i. e., advanced age, right ventricular (RV) myocardial voltage ratio ≥0.58, inducibility of VT after ablation, and longer procedure and fluoroscopy time. In binary logistic regression analysis only RV myocardial voltage ratio ≥0.58 (hazard ratio 11.667, 95% confidence interval 1.487-91.543, p = 0.012) remained associated with an increased risk of VT recurrence.

CONCLUSION

The myocardial voltage ratio (bipolar low voltage area/unipolar low voltage area) as a potential surrogate parameter for scar distribution between the endocardium and the epicardium is significantly associated with the outcome after VT ablation in ARVD/C.

Radiofrequency Ablation Using an Open Irrigated Electrode Cooled With Half-Normal Saline

OBJECTIVES

This study evaluated the use of half-normal saline (HNS) as the radiofrequency ablation (RFA) cooling irrigant.

BACKGROUND

Some instances of ventricular arrhythmia may originate deep within myocardium and can be refractory to standard ablation using open irrigated RFA. Recent data suggest that deeper ablation lesions can be created by decreasing the irrigant ionic concentration delivered through open irrigated RFA than by using normal saline (NS).

METHODS

Bovine myocardium was placed in a circulating saline bath. Two RFA catheters were oriented across from each other, with myocardium in between. Sequential unipolar HNS-irrigated RFA was performed and compared to bipolar ablation by using NS or HNS. Unipolar HNS ablation of the ventricles in a porcine model was performed and compared to ablation using NS.

RESULTS

Sequential ex vivo unipolar RFA with HNS produced larger lesions than sequential unipolar RFA with NS and produced lesions of similar size to those created with bipolar RFA using NS. Ex vivo bipolar RFA using HNS created the largest lesions. In vivo unipolar HNS ablation in porcine endocardium created larger lesion volumes, 152.9 ± 29.2 μl, compared to 94.7 ± 33.4 μl for unipolar ablation using NS.

CONCLUSIONS

By decreasing ionic concentration and charge density in RFA using HNS instead of NS irrigant, larger ablation lesions can be created and are similar in size to lesions created using bipolar ablation. This may be a useful ablation strategy for deep myocardial circuits refractory to standard ablation. Further studies are needed to evaluate this novel RFA strategy.

Safety, long-term outcomes and predictors of recurrence after first-line combined endoepicardial ventricular tachycardia substrate ablation in arrhythmogenic cardiomyopathy. Impact of arrhythmic substrate distribution pattern. A prospective multicentre study

BACKGROUND

First-line endoepicardial ventricular tachycardia (VT) ablation has been proposed for patients with arrhythmogenic cardiomyopathy (AC). This study reports procedural safety, outcomes, and predictors of recurrence.

METHODS AND RESULTS

Forty-one consecutive patients [12 with left ventricle (LV) involvement, 7 left-dominant] underwent first-line endoepicardial VT substrate ablation. Standard bipolar and unipolar thresholds were used to define low-voltage areas (LVA). Arrhythmogenic substrate area (ASA) was defined as the area containing electrograms with delayed components. Implantable cardioverter defibrillator interrogations were evaluated for VT recurrence. Epicardial LVA was larger in all cases (102.5 ± 78.6 vs. 19.3 ± 24.4 cm2; P< 0.001). Consistent with an epicardium-to-endocardium arrhythmogenic substrate progression pattern, epicardial ASA (epi-ASA) was negatively correlated with bipolar endocardial LVA (r = -0.368; P= 0.035) and with endocardial bipolar/unipolar-LVA (Bi/Uni-LVA) ratio (r= -0.38; P= 0.037). A Bi/Uni-LVA ratio >0.23 predicted an epi-ASA ≤10 cm2 (100% sensitivity, 84% specificity). Patients showing an epi-ASA < 10 cm2 required less epicardial (8.4 ± 5.8 vs. 25.3 ± 16; P= 0.045) and more endocardial (16.5 ± 8.6 vs. 7.5 ± 8.2; P= 0.047) radiofrequency applications. One patient with epi-ASA < 10 cm2 died of cardiac tamponade after epicardial puncture. Acute success (no VT inducibility after procedure) was achieved in 36 patients (90%). After 32.2 ± 21.8 months, 11 (26.8%) patients had VT recurrences. Left-dominant AC was associated with an increased risk of recurrence (HR = 3.41 [1.1-11.2], P= 0.044; log-rank P= 0.021).

CONCLUSION

First-line endoepicardial VT substrate ablation achieves good long-term results in AC. Left-dominant AC is associated with an increased risk of recurrence. The Bi/Uni-LVA ratio identifies patients with limited epicardial arrhythmogenic substrate in whom the indication of epicardial approach should be more cautiously assessed.

Transapical approach to optimize left ventricular resynchronization in patients with dilated cardiomyopathy

An alternative to coronary sinus implantation for a left ventricular pacing lead is frequently needed for cardiac resynchronization therapy. We have developed a transapical approach to implant an endocardial pacing lead that will reach the most delayed segment of the left ventricle. This method is easily combined with other transapical heart surgeries. After some technological improvement our technique should offer easier access and better results than other currently available implantation methods.

Transapical approach to optimize left ventricular resynchronization in patients with dilated cardiomyopathy

An alternative to coronary sinus implantation for a left ventricular pacing lead is frequently needed for cardiac resynchronization therapy. We have developed a transapical approach to implant an endocardial pacing lead that will reach the most delayed segment of the left ventricle. This method is easily combined with other transapical heart surgeries. After some technological improvement our technique should offer easier access and better results than other currently available implantation methods.

Outcomes of Combined Endocardial-Epicardial Ablation Compared With Endocardial Ablation Alone in Patients Who Undergo Epicardial Access

Percutaneous epicardial access (EpiAcc) is used in an attempt to improve outcomes of ablation. We aim to report our experience in EpiAcc for management of symptomatic ventricular premature complexes (VPC) and ventricular tachycardia (VT). All patients from January 2004 to July 2014 who underwent EpiAcc as part of a VPC or VT ablation procedure were included. Outcomes between those with endocardial-only (Gp1) and endocardial/epicardial (Gp2) ablation and those for VPC and VT ablation were compared. EpiAcc for VPC or VT ablation was attempted in 173 patients; 10 patients were excluded because of failure of access (n = 7) or no ablation performed (n = 3). Of the remaining 163, 131 patients (80.4%) had undergone previous endocardial ablation. Mean age was 53.7 ± 15.7 years; 115 (71%) were men. VT ablation was the indication in 105 patients (64%). The underlying substrate was predominately nonischemic cardiomyopathy (49.1%). Epicardial ablation was performed in 115 (70.6%). Procedural and clinical success was obtained in 92.0% and 69.9% of patients, respectively, with no difference between Gp1 and Gp2. Those who underwent VPC ablation had superior clinical outcomes at 1-year follow-up. EpiAcc is feasible in almost all patients with no previous cardiac surgery and permits acute procedural success in >90% of patients, most of whom had failed previous ablation. However, epicardial ablation was not delivered in 1/3 of patients. Epicardial mapping may be helpful as in the absence of an appropriate epicardial site for ablation, and focus can be shifted to more detailed endocardial mapping and ablation.

Transseptal Leftventricular Endocardial Pacing is an Alternative Technique in Cardiac Resynchronization Therapy. One Year Experience in a High Volume Center

INTRODUCTION

In patients receiving cardiac resynchronization therapy (CRT), failure rate to implant the left ventricular (LV) lead by the traditional trans-venous approach is 4-8%. Surgical epicardial implantation is considered as an alternative, but this technique is not without morbidity. Evidence from case documentation and from small trial batches demonstrated the viability of endocardial LV lead implantation where surgical epicardial lead placement is not applicable.

MATERIAL AND METHODS

Four patients were implanted with endocardial LV lead using the transseptal atrial approach after unsuccessful transvenous implantation. Implantation of an endocardial active fixation LV leads was successful in all patients with stable electrical parameters immediately after implantation and over the follow-up period. All patients received anticoagulation therapy in order to target the international normalized ratio of 2.5-3.5 and have not experienced any thromboembolic, hemorrhagic events, or infection.

RESULTS

Follow-up echocardiography indicated significant improvement of LV systolic function (24 + 4.9 to 32 + 5.1 %, P = 0.023) with a notable improvement of the functional status.

CONCLUSIONS

Endocardial left ventricular lead implantation can be a valuable and safe alternative technique to enable LV stimulation in high surgical risk patients where standard coronary sinus implant is unsuccessful.

One-and-a-Half Ventricle Repair for Right Ventricular Endomyocardial Fibrosis

One-and-a-half ventricle repair, consisting of endocardiectomy with tricuspid valve replacement and bidirectional cavopulmonary shunt, was performed on a patient with right ventricular endomyocardial fibrosis and right ventricular outflow tract obstruction. The patient made a smooth recovery. We believe that this repair provides good palliation for a subset of patients with right ventricular endomyocardial fibrosis.

Sequential hybrid procedure for persistent atrial fibrillation

BACKGROUND

Catheter ablation of persistent atrial fibrillation yields an unsatisfactorily high number of failures. The hybrid approach has recently emerged as a technique that overcomes the limitations of both surgical and catheter procedures alone.

METHODS AND RESULTS

We investigated the sequential (staged) hybrid method, which consists of a surgical thoracoscopic radiofrequency ablation procedure followed by radiofrequency catheter ablation 6 to 8 weeks later using the CARTO 3 mapping system. Fifty consecutive patients (mean age 62±7 years, 32 males) with long-standing persistent atrial fibrillation (41±34 months) and a dilated left atrium (>45 mm) were included and prospectively followed in an unblinded registry. During the electrophysiological part of the study, all 4 pulmonary veins were found to be isolated in 36 (72%) patients and a complete box-lesion was confirmed in 14 (28%) patients. All gaps were successfully re-ablated. Twelve months after the completed hybrid ablation, 47 patients (94%) were in normal sinus rhythm (4 patients with paroxysmal atrial fibrillation required propafenone and 1 patient underwent a redo catheter procedure). The majority of arrhythmias recurred during the first 3 months. Beyond 12 months, there were no arrhythmia recurrences detected. The surgical part of the procedure was complicated by 7 (13.7%) major complications, while no serious adverse events were recorded during the radiofrequency catheter part of the procedure.

CONCLUSIONS

The staged hybrid epicardial-endocardial treatment of long-standing persistent atrial fibrillation seems to be extremely effective in maintenance of normal sinus rhythm compared to radiofrequency catheter or surgical ablation alone. Epicardial ablation alone cannot guarantee durable transmural lesions.

CLINICAL TRIAL REGISTRATION

URL: www.ablace.cz Unique identifier: cz-060520121617.

An optically coupled sensor for the measurement of currents induced by MRI gradient fields into endocardial leads

OBJECT

The gradient fields generated during magnetic resonance imaging (MRI) procedures have the potential to induce electrical current on implanted endocardial leads. Whether this current can result in undesired cardiac stimulation is unknown.

MATERIALS AND METHODS

This paper provides a detailed description of how to construct an optically coupled sensor for the measurement of gradient-field-induced currents into endocardial leads. The system is based on a microcontroller that works as analog-to-digital converter and sends the current signal acquired from the lead to an optical high-speed, light-emitting diode transmitter. A plastic fiber guides the light outside the MRI chamber to a photodiode receiver and then to an acquisition board connected to a PC laptop.

RESULTS

The performance of the system has been characterized in terms of power consumption (8 mA on average), sampling frequency (20.5 kHz), measurement range (-12.8 to 10.3 mA) and resolution (22.6 µA). Results inside a 3 T MRI scanner are also presented.

CONCLUSIONS

The detailed description of the current sensor could permit more standardized study of MRI gradient current induction in pacemaker systems. Results show the potential of gradient currents to affect the pacemaker capability of triggering a heartbeat, by modifying the overall energy delivered by the stimulator.

[Adult endocardial blood cyst; report of a case]

We report herein a rare case of endocardial blood cyst (EBC) in an adult patient. A 63-year-old asymptomatic woman underwent echocardiography, which incidentally detected a cardiac tumor in the right atrium. On echocardiography, the tumor was revealed to be a 30-mm round mass with thin, hyperechogenic walls and heterogeneously hypoechogenic contents. The lesion was attached to the septum. On computed tomography, the tumor appeared partly calcified and showed poor contrast-enhancement. On magnetic resonance imaging, the lesion appeared isointense or slightly hyperintense in T1 and T2-weighted sequences. Myxoma was strongly suspected based on these preoperative imaging findings. The tumor was successfully excised under cardiopulmonary bypass. Gross examination confirmed that the cyst was filled with blood. The cystic walls comprised thin-layered fibrous tissue lined with endocardial cells. No tumor cells were found. The diagnosis of EBC was confirmed based on histopathological examination, and the postoperative course was uneventful.

Efficacy of TachoSil® as a sutureless hemostatic patch to repair a perforation of the interventricular groove during endocardial radiofrequency ablation

Catheter ablation is a well-established therapeutic option for management of recurrent ventricular tachycardia in patients with ischemic/non-ischemic heart disease and procedural complications include a mortality rate of up to 3% and a risk of major complications up to 10%. Cardiac perforation following a catheter ablation is rare but serious complication and occurs in 1% of ventricular ablation procedures. The appropriate surgical repair may be challenging and need cardiopulmonary bypass support according to the location of the lesion and the hemodynamic status of the patient. We report the case of a free wall right ventricular perforation of the interventricular groove with cardiac tamponade following catheter ablation for recurrent ventricular tachycardia. Due to the proximity of the left anterior descending artery and the extreme fragility of tissues, the patient was treated successfully by a sutureless patch technique using a fibrin tissue-adhesive collagen fleece (TachoSil®). This technique is a safe and effective surgical option to repair a ventricular perforation especially when the ventricular tissues are fragile. It is simple and enable to realize surgical repair also if the localization of tear is difficult to access and without the need for cardiopulmonary bypass support if hemodynamic conditions are stable.

Analysis of endocardial acceleration during intraoperative optimization of cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is the therapy of choice for selected patients suffering from drug-refractory congestive heart failure and presenting an interventricular desynchronization. CRT is delivered by an implantable biventricular pacemaker, which stimulates the right atrium and both ventricles at specific timings. The optimization and personalization of this therapy requires to quantify both the electrical and the mechanical cardiac functions during the intraoperative and postoperative phases. The objective of this paper is to evaluate the feasibility of the calculation of features extracted from endocardial acceleration (EA) signals and the potential utility of these features for the intraoperative optimization of CRT. Endocardial intraoperative data from one patient are analyzed for 33 different pacing configurations, including changes in the atrio-ventricular and inter-ventricular delays and different ventricular stimulation sites. The main EA features are extracted for each pacing configuration and analyzed so as to estimate the intra-configuration and inter-configuration variability. Results show the feasibility of the proposed approach and suggest the potential utility of EA for intraoperative monitoring of the cardiac function and defining optimal, adaptive pacing configurations.

Safety, long-term results, and predictors of recurrence after complete endocardial ventricular tachycardia substrate ablation in patients with previous myocardial infarction

Conduction channels and electrograms with isolated component/late potentials are sensitive markers of the substrate of post-myocardial infarction sustained monomorphic ventricular tachycardia (VT). Ablation of all conduction channels and isolated component/late potentials (complete endocardial VT substrate ablation [CEVTSA]) during sinus rhythm could simplify and facilitate the ablation procedure, mainly in patients without references for clinical VT substrate identification. The aim of this study was to assess the safety, efficacy, and predictors of VT recurrence after CEVTSA. Electroanatomic mapping and CEVTSA were performed in 59 post-myocardial infarction patients (mean age 67 ± 9 years, mean left ventricular ejection fraction 30 ± 11%), 24 of whom did not have clinical VT substrate references. The mean areas of scar (≤1.5 mV) and dense scar (≤0.5 mV) were 76 ± 42 and 34 ± 24 cm(2), respectively; isolated component/late potentials and conduction channels were identified and ablated in 97% and 83% of patients (mean ablation area 14 ± 10 cm(2)). No life-threatening complications occurred during the procedure. After 1 year and at the end of follow-up (mean 39 ± 21 months), 81% and 58% of patients were free of VT. No differences were observed between patients with and without specific clinical VT substrate identification. Univariate analysis identified the left ventricular ejection fraction, VT cycle length (VTCL), infarct location (inferior vs anterior), and dense scar area as predictors of VT recurrence, and Cox analysis identified VTCL (hazard ratio 0.42, p <0.001) and dense scar area (hazard ratio 2.65, p <0.0006) as independent predictors. No patients with dense scar area ≤25 cm(2) and VTCL >350 ms had recurrences. In conclusion, CEVTSA is safe and effective, even in patients without clinical VT substrate identification. Scar area and VTCL are valuable predictors of VT recurrence.

[Thoracoscopic ablation of atrial fibrillation]

Atrial fibrillation is often a disabling arrhythmia which can be alleviated by ablation procedures. The cornerstone procedure pulmonary vein isolation is generally performed using a transvenous approach transseptally. Endocardial technique can cause as complications arterial embolisation, pulmonary vein stenosis and oesophageal damage. Endocardial isolation has to be repeated often without predictable outcome. Pulmonary vein isolation can be performed with beating heart also mini-invasively in a thoracoscopic way. The procedure is suggested to be combined with ganglionated plexus ablation and resection of left atrial appendage. The results of both endocardial and epicardial isolation of pulmonary veins (hybrid therapy) have been promising. These two techniques are not competing with each other but are complementary. The epicardial procedure has more complications and the choice of therapy line should be considered carefully.

Postmyocardial infarction left ventricular dysfunction - assessment and follow up of patients undergoing surgical ventricular restoration by the endoventricular patchplasty

BACKGROUND

Surgical ventricular restoration with endoventricular patchplasty improves left ventricular function and restores left ventricular shape.

METHOD

The study included patients who presented with transmural anterior myocardial infarctions between June 2007 and May 2008. Briefly the technique included - coronary revascularization, resection of the endocardial scar, left ventricular reconstruction using an endoventricular synthetic patch. Left ventricular geometric parameters were studied preoperatively, early postoperatively, at 3 and 6 months and statistically analyzed by SPSS 14 software package.

RESULTS

The ejection fraction increased from 33.5 ± 5.02 to 37.77 ± 7.17 immediate postoperatively. The preoperative left ventricular ejection fraction - a mean of 33.25% (±5.02%), increased by 10.3%-11% at the third and fourth follow up respectively after surgical ventricular restoration (p ≤ 0.001). The left ventricular end systolic volume index improved from a mean of 48.84 ± 11.37 preoperatively to 24.66 ± 5.92 postoperatively (p ≤ 0.001).

CONCLUSIONS

Surgical ventricular restoration in our study has clearly demonstrated a positive effect on LV geometry.

Endomyocardial biopsy for monitoring heart transplant patients: 11-years-experience at a german heart center

BACKGROUND

Heart transplantation (HTX) has become an established therapy for patients with end-stage heart failure. Endomyocardial biopsy (EMB) still represents the gold standard for routine surveillance of heart transplant rejection. The objective of this article is to report our experience regarding the use of EMB in monitoring heart transplant recipients.

METHODS

We evaluated retrospectively all patients who underwent orthotopic HTX between 2000 and 2011 at our hospital. From all patients, we created a follow-up, determined the number of EMB events and described the complications associated with this procedure.

RESULTS

HTX was performed in 142 cases at our center in the last 11 years (1.3% of the total of 10693 cardiac surgical operations in that period). Further 9 patients visited our department for monitoring after HTX performed at an external center (total: 151). For all patients, a total of 1896 EMB events have been recorded. The majority of biopsies were performed through the right internal jugular vein. The overall complication rate was 1% (n=19).

CONCLUSIONS

The histological examination of right ventricular EMB still represents the gold standard of care for cardiac allograft rejection monitoring. EMB is an invasive, but safe and dedicated diagnostic procedure. However, the usefulness of recent non-invasive diagnostic approaches as an adjunct tool in monitoring for rejection remains to be further analyzed.

[Comparison of effectiveness of radiofrequency catheter ablation of left arterial isthmuses for treatment of postablational perimitral atrial flutter]

AIM

To compare results of radiofrequency (RF) ablation (A) of mitral and inferior septal isthmuses in the left atrium for the treatment of perimitral atrial flutter (AF) in patients with atrial fibrillation previously subjected to RF isolation of pulmonary veins and modification of the left atrial anatomical arrhythmia substrate.

MATERIAL AND METHODS

We treated 20 patients (3 women, mean age 57.1+/-9.3 years) with recurrent postablational perimitral AF verified by 3-dimensional reconstruction of left and right atrial activation by nonfluoroscopic mapping and pacing techniques of entrainment into tachycardia cycle. At first stage RFA was carried out in the region of mitral isthmus (its endocardial parts). At second stage RFA was performed in the region of coronary sinus (CS) roof (epicardial portions of the mitral isthmus). At the third stage RFA influences were applied in the region of inferior septal isthmus (endocardial portions of the inferioseptal isthmus). At the fourth stage RFA was applied in the region of roof of proximal CS (epicardial portions of inferioseptal isthmus).

RESULTS

Application of RF influences to endocardial parts of the mitral isthmus resulted in sinus rhythm (SR) restoration in 6 cases. Change of length of the tachycardia cycle was noted in 5cases. SR restoration was observed after RFA in the region of the roof of distal CS in 3 cases and change of length of the tachycardia cycle was noted in 2 more cases. RFA of epicardial parts of the inferioseptal isthmus resulted in SR restoration in 3 cases and in increase of atypical AF cycle length in 6 cases. In 12 cases SR was restored during RFA application in the region of the roof of proximal CS parts. RF influences in the region of endocardial (stage 1) and epicardial (stage 2) parts of the mitral isthmus resulted in SR restoration in 9 cases while continuation of RFA in the region of endocardial (stage 3) and epicardial (stage 4) parts of the inferioseptal isthmus led to SR restoration in the remaining 15 cases (p<0.05).

CONCLUSION

RFA of endocardial and epicardial parts of the inferioseptal isthmus significantly more often led to termination of perimitral atypical AF in patients previously operated because of atrial fibrillation.

[Long-term results and analysis of multiple surgical approaches for ischemic cardiomyopathy with left ventricular reconstruction, including scarred endocardiectomy for arrhythmia therapy, and mitral valve surgery]

Among 73 patients with ischemic cardiomyopathy [ejection fraction (EF) < 40%, left ventricular end systolic volume index (LVESVI) > 60 ml/m2], 65 patients with large scar underwent left ventricular reconstruction (LVR) including scarred endocardiectomy against arrhythmia and 13 with 3 + mitral regurgitation (MR) mitral valve surgery [mitral annular plasty (MAP): n = 9, mitral valve replacement (MVR): n = 4]. Eight-year survival including 1 perioperative death (1.4%) was 773% without death due to arrhythmia. 69 survivors revealed significant improvement in New York Heart Association (NYHA) class, and lefe ventricular (LV) function in pulmonary artery pressure (PAP) and EF. LV volume significantly reduced from 103.6 to 57.5 ml/m2 in LVESVI (44% volume reduction) [p < 0.0001]. Postoperative LV shape became significantly spherical [eccentricity index (EI) closer to 0], however, MR grade was significantly reduced from 2.0 to 1.6 (p < 0.0003). Freedom from all deaths including hospitalization for cardiac causes was 71.1% at 8 years. One patient required implantable cardioverter defibrillator (ICD) for spontaneous ventricular tachycardia (VT). Multivariate Cox's regression model showed that preoperative large left ventricular end diastolic volume index (LVEDVI) [hazard ratio (HR) 1.02], postoperative large LVESVI (HR 1.03) and preoperative high NYHA class (HR 3.05) were significant risk factors affecting all deaths including hospitalization for cardiac causes. Of 24 patients with 2.5 + MR, mitral valve surgery (MAP, MVR or MAP + LVR) demonstrated significant improvement of MR (3.6 to 1.3 in MAP/MVR and 3.5 to 1.0 in MAP + LVR) compared with isolated LVR (2.6 to 2.2), although, there was no significant change in LV volume reduction. Our surgical approach to ischemic cardiomyopathy revealed excellent long-term results without death due to arrhythmia. Risk factor analysis recommended earlier and more aggressive surgical approach to achieve both LV volume reduction, MR and arrhythmia control.

Effects of adipose tissue-derived stem cell therapy after myocardial infarction: impact of the route of administration

BACKGROUND

Cell-based therapies offer a promising approach to reducing the short-term mortality rate associated with heart failure after a myocardial infarction. The aim of the study was to analyze histological and functional effects of adipose tissue-derived stem cells (ADSCs) after myocardial infarction and compare 2 types of administration pathways.

METHODS AND RESULTS

ADSCs from 28 pigs were labeled by transfection. Animals that survived myocardial infarction (n = 19) received: intracoronary culture media (n = 4); intracoronary ADSCs (n = 5); transendocardial culture media (n = 4); or transendocardial ADSCs (n = 6). At 3 weeks' follow-up, intracoronary and transendocardial administration of ADSCs resulted in similar rates of engrafted cells (0.85 [0.19-1.97] versus 2 [1-2] labeled cells/cm(2), respectively; P = NS) and some of those cells expressed smooth muscle cell markers. The intracoronary administration of ADSCs was more effective in increasing the number of small vessels than transendocardial administration (223 +/- 40 versus 168 +/- 35 vessels/mm(2); P < .05). Ejection fraction was not modified by stem cell therapy.

CONCLUSIONS

This is the first study to compare intracoronary and transendocardial administration of autologous ADSCs in a porcine model of myocardial infarction. Both pathways of ADSCs delivery are feasible, producing a similar number of engrafted and differentiated cells, although intracoronary administration was more effective in increasing neovascularization.

Commissural autologous pericardial patch repair: a novel technique for active mitral valve endocarditis involving the mitral annulus

In patients with massive destruction caused by mitral endocarditis, surgical valve repair remains a challenging issue. Although several procedures have previously been introduced, no standard method for complicated lesions has been established. We describe a technique of mitral valve repair for extensive destructive endocarditis involving both leaflets and the mitral annulus that has provided satisfactory initial results in 2 patients. This procedure is believed to be technically simple and beneficial in terms of mitral repair for active endocarditis.

Endocardial substrate mapping for monomorphic ventricular tachycardia ablation in ischemic and non-ischemic cardiomyopathy

We investigated the differences in the endocardial substrates between ischemic cardiomyopathy (ICM) and non-ICM (NICM) by using electro-anatomical mapping and pace-mapping. We studied 18 patients (ICM and NICM, 9 each) with monomorphic ventricular tachycardia (VT) documented by 12-leads ECG. Low voltage area was defined by signal amplitude <1.5 mV. A pace-map QRS morphology that matched VT in >10 of the 12-leads ECG was regarded as a pace-map match. And conduction delay during pace-mapping was defined as the stimulus to QRS interval >or=40 ms. Low voltage area was 53.8 +/- 21.5 and 20.8 +/- 16.7 cm2 in ICM and NICM patients, respectively (P = 0.002). Pace-mapping was assessed in 6 ICM and 9 NICM. Pace-map match with conduction delay were obtained in all the 6 ICM patients. But in NICM patients, pace-map match with conduction delay was obtained in 3 patients. Pace-map match sites where conduction delay was not observed were obtained in 5 patients. Pace-map match could not be obtained in 1 patient. We attempted ablation in 6 ICM and 7 NICM patients. Subsequently, VT recurrence was not observed in ICM but it was observed in 6 of 7 NICM patients (log-rank P = 0.0016). In NICM patients, the arrhythmogenic substrate that represented the abnormal electrogram and conduction delay was observed less within the endocardial surface when compared with that observed in ICM. VT recurrence rate subsequent to endocardial ablation was higher in NICM than in ICM patients.

Hybrid Epicardial and Endocardial Ablation of Persistent or Permanent Atrial Fibrillation: A New Approach for Difficult Cases

BACKGROUND

Although percutaneous epicardial catheter ablation (PECA) has been used for the management of epicardial ventricular tachycardia, the use of PECA for atrial fibrillation (AF) has not yet been reported.

OBJECTIVE

To evaluate the efficacy and feasibility of a hybrid PECA and endocardial ablation for AF.

METHODS

We performed PECA for AF in five patients (48.6 +/- 8.1 years old, all male, four redo ablation procedures of persistent AF with a risk of pulmonary vein (PV) stenosis, one de novo ablation of permanent [AF]) after an endocardial AF ablation guided by PV potentials and 3D mapping (NavX). Utilizing an open irrigation tip catheter, a left atrial (LA) linear ablation from the roof to the perimitral isthmus or localized ablation at the junction between the LA appendage and left-sided PVs or ligament of Marshall (LOM) was performed.

RESULTS

PECA of AF was successful in all patients with an ablation time of <15 minutes. The left-sided PV potentials were eliminated by PECA in all patients. Bidirectional block of the perimitral line was achieved in two of two patients and a left inferior PV tachycardia with conduction block to the LA was observed during the ablation in the area of the LOM in one patient. A hemopericardium developed in one patient, but was controlled successfully. During 8.0 +/- 6.3 months of follow-up, all patients have remained in sinus rhythm (four patients without antiarrhythmic drugs).

CONCLUSION

A hybrid PECA of AF is feasible and effective in patients with redo-AF ablation procedures and at risk for left-sided PV stenosis or who are resistant to endocardial linear ablation.

Initial Experience With a Telerobotic System to Remotely Navigate and Automatically Reposition Standard Steerable EP Catheters

The use of robotic systems in cardiac interventional procedures is growing. The insertion and maneuvering in the human body of electrophysiology (EP) catheters is currently carried out manually under fluoroscopic guidance, resulting in operator fatigue and prolonged x-ray exposure. We report our initial animal experience with a novel telerobotic system (TS) to remotely navigate and automatically reposition standard steerable EP catheters within the heart. We developed a TS able to guide, as a "robotic hand," EP catheters without the need of dedicated catheters and cumbersome devices. During tests on three sheep, catheter navigation and repositioning to 12 predefined endocardial targets were previously performed by conventional manual procedure and then using the TS implemented with an automatic catheter repositioning function. All the predefined targets were reached under fluoroscopy visualization, and procedural times were measured during catheter navigation and repositioning. The use of the TS slightly reduced the time necessary for catheter navigation compared with the conventional manual procedure (13.0 +/- 5.6 vs 16.1 +/- 6.4 seconds, p < 0.001) and significantly decreased the time for a precise catheter repositioning (9.2 +/- 2.5 vs 17.8 +/- 7.1 sec, p < 0.001). The TS proved to be a promising tool for remote navigation of standard EP catheters reducing the time necessary for catheter repositioning.

Comparison of transendocardial and retrograde coronary venous intramyocardial catheter delivery systems in healthy and infarcted pigs

We compared two routes for myocardial delivery of therapeutics, transendocardial (TE) delivery with an intramyocardial injection catheter, and retrograde coronary venous (RCV) delivery with a balloon occlusion catheter in the interventricular vein.

METHODS

TE and RCV injection of 15 microM, neutron-activatable microspheres was compared in healthy pigs (Group I, n = 3), pigs with a 1-week-old myocardial infarction (MI; group II, n = 5), and pigs with a 2-weeks-old MI (group III, n = 4). The MI was induced by a 1-hr balloon occlusion in the LAD. Both methods were compared in the same animal using different microspheres. The RCV catheter allowed for continuous measurement of distal pressure and 2.5 x 10(6) microspheres were injected in 10 ml at 300 mmHg above balloon occlusion pressure. The TE injections were targeted to the infarct zone and 2.5 x 10(6) microspheres were distributed over 10 injections of 200 microl.

RESULTS

The retention of microspheres decreased with increase in MI age, but was comparable between devices within the groups. RCV delivery resulted in (14.3 +/- 0.9)% microsphere retention in Group I, (10.3 +/- 0.2)% in Group II, and (6.4 +/- 0.1)% in group III (P < 0.05 versus group I). Microsphere retention after TE was (15.1 +/- 0.7)% in group I, (18.9 +/- 0.6)% in group II, (4.1 +/- 0.1)% in Group III (P < 0.05 versus groups I and II). The RCV catheter delivered primarily to midventricular, antero-septal segments, whereas TE targeted apical areas predominantly.

CONCLUSIONS

Delivery efficacy was comparable between devices in each group however RCV targeted midventricular areas whereas TE targeted apical areas.

Impact of Catheter Ablation of the Coronary Sinus on Paroxysmal or Persistent Atrial Fibrillation

OBJECTIVES

This study evaluated the impact of catheter ablation of the coronary sinus (CS) region during paroxysmal and persistent atrial fibrillation (AF).

BACKGROUND

The CS musculature and connections have been implicated in the genesis of atrial arrhythmias.

METHODS

Forty-five patients undergoing catheter ablation of AF were studied. The CS was targeted if AF persisted after ablation of pulmonary veins and selected left atrial tissue. CS ablation was commenced endocardially by dragging along the inferior paramitral left atrium. Ablation was continued from within the vessel (epicardial) if CS electrograms had cycle lengths shorter than that of the left atrial appendage. RF energy was limited to 35 W endocardially and 25 W epicardially. The impact of ablation was evaluated on CS electrogram cycle length (CSCL) and activation sequence, atrial fibrillatory cycle length measured in the left atrial appendage (AFCL) and on perpetuation of AF.

RESULTS

Endocardial ablation significantly prolonged CSCL by 17 +/- 5 msec and organized the CS activation sequence (from 13% of patients before to 51% after ablation); subsequent epicardial ablation further increased local CSCL by 32 +/- 27 msec (P < 0.001). AFCL prolonged significantly both during endocardial and epicardial ablation (median: 152 to 167 msec P = 0.03) and was associated with AF termination in 16 (35%) patients (46% of paroxysmal and 30% of persistent AF). AFCL prolongation > or =5 msec and/or AF termination was associated with more rapid activity in the CS region originally: P < or = 0.04.

CONCLUSION

Catheter ablation targeting both the endocardial and epicardial aspects of the CS region significantly prolongs fibrillatory cycle length and terminates AF persisting after PV isolation in 35% of patients.

Catheter ablation of haemodynamically unstable or non-sustained ventricular tachycardia

BACKGROUND

Ventricular tachycardia (VT) may be haemodynamically unstable or non-sustained, interfering with detailed activation mapping. Non-contact mapping permits beat-by-beat analysis of VT, projected upon a 3-dimensional reconstructed geometry of the cardiac chamber. Objective - The aim of the present study is to determine the utility of non-contact endocardial mapping to guide ablation of haemodynamically unstable VT or non-sustained VT.

METHODS AND RESULTS

Eighteen VTs in 17 patients were induced (cycle length 336 +/- 58 ms) and mapped. Three patients were mapped during premature ventricular complexes (PVCs) because sustained VT could not be induced. Analysis of the archived non-contact activation maps was performed to identify the exit point and/or the diastolic pathway of theVT reentry circuit. The endocardial exit points (10 +/- 16 ms before QRS) were defined in 17/18 VTs (94%). A diastolic pathway was identified in 5/6 ischaemic VTs. The earliest activation sites were identified in all 3 patients with PVCs. Radiofrequency current was applied around the exit point or to create a line of block across the diastolic pathway. Catheter ablation was performed in 17/18 VTs, including 3 patients mapped using only PVCs. Ablation was successful in 16/18 VTs (89%) and in 1 5/17 patients (82%). Catheter ablation was not performed in one patient (peri-hisian VT) and was unsuccessful in one patient (mapped during PVCs).

CONCLUSIONS

Non-contact endocardial mapping is useful to guide radiofrequency catheter ablation of untolerated or non-sustained VTs.