A System for Accurate Deployment of Unconstrained Triple-Fenestrated Aortic Arch Endografts

Purpose: To achieve accurate rotational orientation and the axial position of unconstrained triple-fenestrated physician-modified endografts upon deployment in the aortic arch during total arch thoracic endovascular aortic repair (TA-TEVAR). Materials and Methods: Following a detailed study of reconstructed computerized tomography angiography images of patients’ arch anatomy, customized, sealable fenestrations with radio-opaque margins are created onsite on Valiant Captivia (Medtronic) endografts, transposing the arch branch ostial anatomic interrelationship onto the endograft precisely. Radio-opaque figure-of-8 markers, indicating the 12 o’clock (superior) position, are attached to the endograft on the surface and brought up to the surface under the endograft cover during resheathing. Resheathing without any twist in the endograft is achieved by lining up the welds in each endograft stent segment in a straight line. The fluoroscopic working view for arch endograft delivery and deployment is the left anterior oblique view that is orthogonal to the plane of the arch, which, in turn, is the right anterior oblique view in which parts of a stiff indwelling guidewire in the ascending and descending aorta precisely overlap. During introduction in the working view, the endograft delivery system is rotated in the descending thoracic aorta so that the 12 o’clock figure-of-8 markers are viewed on the edge and situated at the outer aortic curvature; continued advancement into the arch without any further rotation will ensure superior orientation of the figure-of-8 markers and, consequently, correct endograft rotational orientation. Proper axial endograft positioning requires locating the left common carotid artery (LCCA) fenestration just proximal to a taut externalized LCCA-femoral guidewire loop marking the posterior limit of the LCCA ostium. After endograft deployment during rapid cardiac pacing, the target arch branches are cannulated through their respective fenestrations using hydrophilic 0.035-inch guidewires that are externalized via distal sheaths to create femoral-arch branch (through-and-through) loops over which covered fenestrated stents are introduced and deployed. Results: This technique was used successfully in 31 consecutive patients undergoing TA-TEVAR; systemic blood pressure was obtained in all arch branches immediately after endograft deployment, indicating adequate blood flow. All arch branches were successfully cannulated and stented. Conclusion: This system enables accurate deployment of unconstrained triple-fenestrated arch endografts simply and reliably during TA-TEVAR.

Cardiac Pacing in Cardioinhibitory Reflex Syncope: Clinical Use of Closed-loop Stimulation

Cardiac pacing has been studied extensively in patients with reflex syncope over the past two decades. The heterogeneity of the forms and clinical manifestations of reflex syncope explain the controversial results of older randomised clinical trials. New evidence from recent trials has changed medical practice, now leading to clear indications for pacing in patients with asystolic syncope documented during carotid sinus massage, implantable cardiac monitoring or tilt testing. Given that recent trials in reflex syncope have been performed using the closed-loop stimulation algorithm, the authors will briefly discuss this pacing mode, review hypotheses about the mechanisms underlying its activation during syncope and provide practical instructions for programming and troubleshooting.

Advances in Cardiac Pacing: Arrhythmia Prediction, Prevention and Control Strategies

Cardiac arrhythmias constitute a tremendous burden on healthcare and are the leading cause of mortality worldwide. An alarming number of people have been reported to manifest sudden cardiac death as the first symptom of cardiac arrhythmias, accounting for about 20% of all deaths annually. Furthermore, patients prone to atrial tachyarrhythmias such as atrial flutter and fibrillation often have associated comorbidities including hypertension, ischemic heart disease, valvular cardiomyopathy and increased risk of stroke. Technological advances in electrical stimulation and sensing modalities have led to the proliferation of medical devices including pacemakers and implantable defibrillators, aiming to restore normal cardiac rhythm. However, given the complex spatiotemporal dynamics and non-linearity of the human heart, predicting the onset of arrhythmias and preventing the transition from steady state to unstable rhythms has been an extremely challenging task. Defibrillatory shocks still remain the primary clinical intervention for lethal ventricular arrhythmias, yet patients with implantable cardioverter defibrillators often suffer from inappropriate shocks due to false positives and reduced quality of life. Here, we aim to present a comprehensive review of the current advances in cardiac arrhythmia prediction, prevention and control strategies. We provide an overview of traditional clinical arrhythmia management methods and describe promising potential pacing techniques for predicting the onset of abnormal rhythms and effectively suppressing cardiac arrhythmias. We also offer a clinical perspective on bridging the gap between basic and clinical science that would aid in the assimilation of promising anti-arrhythmic pacing strategies.

Second-Degree Type 2 Atrioventricular Block Requiring Permanent Cardiac Pacing in Patients on CDK4/6 Inhibitors: Report of Two Cases

<b><i>Introduction:</i></b> A wide spectrum of cardiovascular (CV) toxicity is associated with anticancer treatment, and nearly all chemotherapeutic agents can elicit CV toxicity. Inhibitors of cyclin-dependent kinases 4/6 (CDK4/6Is) have become standard of care in the treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer (MBC). CV side effects are uncommon with CDK4/6Is and only include QT prolongation, with a low incidence rate. <b><i>Case Presentation:</i></b> This paper describes 2 cases of new-onset second-degree type 2 atrioventricular (AV) blocks requiring permanent cardiac pacing involving 2 women with MBC receiving ribociclib or abemaciclib. Both our patients had no known history or risk factors of cardiac disease and a normal 12-lead resting electrocardiogram (ECG) when diagnosed with breast adenocarcinoma. Both patients have been subjected to surveillance for cardiotoxicity with serial ECG and echocardiography. No left ventricular dysfunction or arrhythmia was found during the follow-up, and cardiac biomarkers were normal. <b><i>Conclusion:</i></b> To our knowledge, these are the first cases reported in the literature of new-onset advanced AV blocks in patients under treatment with CDK4/6Is, suggesting the clinical relevance of a more frequent ECG monitoring, besides the QT interval, in these patients.

Wide Area Uniform Illumination Scheme Using LED Matrix for Optogenetic Cardiac Pacing

Control of heart rhythm is vital in the case of arrhythmia. Cardiac optogenetics is a promising technique to replace electrical stimulation in a next generation of pacemakers and defibrillators. Therefore, further research towards optimizing light delivery methods is essential. A major requirement is the uniform stimulation of all cells in the area of interest while reducing side effects such as photodamage. Here, a 2 × 2 blue (470 nm, InGaN-based) light-emitting diode (LED) optoelectronic module for uniform ex vivo cardiac muscle illumination is demonstrated. It satisfies two important requirements in optogenetics, which are high illumination homogeneity and high irradiance. CCD camera images show an average 90% homogeneity over the central illumination area of close to 38 mm2 at 1 cm distance from the light source. The module is used to perform physiological experiments on channelrhodopsin 2-expressing Langendorff-perfused mouse hearts. Successful ventricular pacing is obtained for an optical power density threshold below 2 mW/mm2 with light pulses as short as 1 ms. For 10 ms long pulses, the threshold was below 0.2 mW/mm2. The large homogeneous illumination area enabled optogenetic pacing with less than half the optical power of previous attempts with smaller areas of 2 mm2 and thus, presumably, will result in less phototoxicity.

Cardiac implantable electronic devices in Bulgaria: results from the electronic registry BG-Pace for the period 2019-2021

The current study analyses the activity in cardiac pacing in Bulgaria in 2019, 2020 and 2021 based on data derived from a national registry of patients with cardiac electronic implantable devices (CIEDs). Materials and methods. Data from the national registry BG-Pace in the period 08.2019-06.2021 was retrospectively studied. Demographic data, procedure and device type, pacing mode, etiology, symptoms, preimplantation ECG, number of implantations and centre and operator volumes were analysed. Results. Six thousand nine hundred forty-nine devices were implanted by 47 operators in 28 centres for the study period. Median age was 75 (IQR 68-81, 21-103) years in males and 77 (IQR 71-82, 17-98) years in females, P< 0.05. The largest number of devices were implanted in the age group 70-79 years. The most commonly implanted CIEDs were antibradycardia devices with a total of 486.7/million implantations for the period 08.2019-08.2020 and 353.9/million for the period 08.2020-06.2021. Implanted cardioverter-defibrillators demonstrated a growth from 14.1/million to 20.1/million in the period 08.2020 – 06.2021. The number of all implantations dropped signifi cantly during the two epidemic waves of COVID-19. The mean number of implantations per centre and per operator for the whole period was 232.3±204 (2-705) and 148±139.1 (2-660), respectively. Dual chamber device implantations were more prevalent, representing 65.8% of implantations in AV block I and II degree, 63.5% in complete AV block, 59.8% in intraventricular conduction disturbances and 60.9% in sick sinus syndrome. Pacing modes with atrial sensing represented more than 55% of the implantations for all indications. Increasing age was associated with signifi cantly more common use of VVI pacing mode (P < 0.001). Conclusion. The national registry BG-Pace includes systematic clinical, demographical and procedural data for CIED implantations in Bulgaria. Results demonstrate lower number of implantations compared to the average European volume. There was a signifi cant drop in the implantation rate during the two waves of COVID-19.