Ventricular Arrhythmias in Left Ventricular Assist Device Patients-Current Diagnostic and Therapeutic Considerations

Left ventricular assist devices (LVAD) are used in the treatment of advanced left ventricular heart failure. LVAD can serve as a bridge to orthotopic heart transplantation or as a destination therapy in cases where orthotopic heart transplantation is contraindicated. Ventricular arrhythmias are frequently observed in patients with LVAD. This problem is further compounded as a result of diagnostic difficulties arising from presently available electrocardiographic methods. Due to artifacts from LVAD-generated electromagnetic fields, it can be challenging to assess the origin of arrhythmias in standard ECG tracings. In this article, we will review and discuss common mechanisms, diagnostics methods, and therapeutic strategies for ventricular arrhythmia treatment, as well as numerous problems we face in LVAD implant patients.

Magnetic resonance imaging in patients with implanted cardiac electrotherapy devices: a statement from experts of the Polish Medical Society of Radiology, the Polish Society of Cardiology, and the Polish Society of Electroradiology

The year 2023 marks 60 years since the first pacemaker was implanted in Poland. The number of implantable cardiac electrotherapy devices (CIEDs), including pacemakers, cardioverter-defibrillators, and resynchronization therapy systems, has been systematically increasing in the subsequent decades. It is estimated that nearly 500,000 Poles have an implanted cardiac electrotherapy device, making optimal diagnostic imaging with the use of magnetic resonance imaging (MRI) a clinically and epidemiologically important issue. MRI has become a gold diagnostic standard in many disease states. In this situation, it is believed that 50-70% of patients who have a cardiac electrotherapy device may have indications for an MRI examination later in life. For many years, an implanted cardiac electrotherapy device was considered a definite contraindication to MRI. However, MRI has become possible in most patients with CIED if certain procedures and precautions are followed. In these guidelines, we describe the basic rules that should be followed in order to perform a safe MRI examination in patients with different CIEDs. Despite all the risks and organizational factors described in the text, it seems that for many MRI departments, MRI in patients with CIEDs is achievable and should be implemented immediately. A second important issue is the need for dedicated financial support for these procedures from public health insurance.

Diagnostic electrocardiographic trap: A case of conduction system pacing

His-bundle pacing (HBP) is a relatively new method of cardiac pacing, with recent studies showing an association between HBP and a lower risk of developing right ventricular heart failure compared to classical pacing methods. However, HBP is also associated with a higher risk of lead dislodgement, undersensing, and loss of capture. As such, a detailed assessment of pacing effectiveness in pacemaker patients is vital. In the presented case, an electrocardiogram (ECG) recording seems to present successful selective His-bundle pacing, while pacemaker follow-up demonstrated the loss of ventricular capture. In conclusion, patients receiving HBP should undergo ECG alongside pacing parameter analysis and pacing electrograms, as differences in successful and unsuccessful pacing ECG can be very subtle.

Rate-Responsive Cardiac Pacing: Technological Solutions and Their Applications

Modern cardiac pacemakers are equipped with a function that allows the heart rate to adapt to the current needs of the patient in situations of increased demand related to exercise and stress ("rate-response" function). This function may be based on a variety of mechanisms, such as a built-in accelerometer responding to increased chest movement or algorithms sensing metabolic demand for oxygen, analysis of intrathoracic impedance, and analysis of the heart rhythm (Q-T interval). The latest technologies in the field of rate-response functionality relate to the use of an accelerometer in leadless endocavitary pacemakers; in these devices, the accelerometer enables mapping of the mechanical wave of the heart's work cycle, enabling the pacemaker to correctly sense native impulses and stimulate the ventricles in synchrony with the cycles of atria and heart valves. Another modern system for synchronizing pacing rate with the patient's real-time needs requires a closed-loop system that continuously monitors changes in the dynamics of heart contractions. This article discusses the technical details of various solutions for detecting and responding to situations related to increased oxygen demand (e.g., exercise or stress) in implantable pacemakers, and reviews the results of clinical trials regarding the use of these algorithms.

Use of an exercise test to enhance sensing vector assessment and prevent inadequate subcutaneous implantable cardioverter-defibrillator discharges

Subcutaneous implantable cardioverter-defibrillators are a modern alternative to classic cardioverter-defibrillators. Prior to implantation of the device, qualification based on assessment of the heart's specific rhythm shape during a resting electrocardiogram examination must be performed. In the presented case, a patient with a subcutaneous implantable cardioverter-defibrillator experienced numerous discharges during exercise. An exercise test was performed, which revealed a bundle branch block that appeared during exercise. The wide QRS complex was double- or triple-counted by the device, resulting in an inaccurate heart rate estimation and multiple discharges. Optimising the sensing vectors during exercise solved this problem.