DOI: 10.33963/KP.15824, Published online: February 24, 2021, Authors: Ryszard Piotrowicz^1,2, Paweł Krzesiński³, Paweł Balsam⁴, Ewa Piotrowicz⁵, Maciej Kempa⁶, Ewa Lewicka⁶, Renata Główczyńska⁴, Marcin Grabowski⁴, Łukasz Kołtowski⁴, Michał Peller⁴, Bartosz Szafran⁷, Justyna Zajdel-Całkowska⁸, Jan Pachocki⁹, Jakub Podolec^10,11, Adam Stańczyk^12,13, Grzegorz Opolski⁴

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.

BACKGROUND Prolonged QT interval is an integral part of the definition of cirrhotic cardiomyopathy. The aim of this study was to analyze the relationship between QT corrected (QTc) and the etiology and the severity of liver disease in relation to the complications of cirrhosis in candidates for orthotropic liver transplantation (OLTx). MATERIAL AND METHODS From 360 consecutive patients with end-stage liver disease (ESLD) consulted by a designated cardiologist, 160 patients underwent OLTx. The QTc was calculated according to 3 formulas in 151 ECG tracings with good quality. The severity of liver disease was assessed according to Child-Pugh classification and model for end-stage liver disease (MELD). This was a single-center study with register-based follow-up design. RESULTS Prolonged QTc over 440 ms was found in 51 subjects (33.8%), but none had prolonged QTc >500 ms. QTc corrected by Fridericia (F) formula was more suitable for patients with ESLD. We found no correlation between QTc interval and severity of liver disease. The QTc interval was higher in patients with alcoholic cirrhosis when compared to patients with viral hepatitis and ESLD of other etiologies. We observed a higher QTc interval in patients with gastroesophageal varices and encephalopathy. We did not notice any significant difference in the effect of the QTc interval on survival. CONCLUSIONS QTc interval might be associated with etiology and complication of ESLD. The prolonged QT interval is not associated with higher all-cause mortality after OLTx.

Cirrhotic cardiomyopathy (CCM) is a relatively new medical term. The constant development of novel diagnostic and clinical tools continuously delivers new data and findings about this broad disorder. The purpose of this review is to summarize current facts about CCM, identify gaps of knowledge, and indicate the direction in which to prepare an updated definition of CCM. We performed a review of the literature using scientific data sources with an emphasis on the latest findings. CCM is a clinical manifestation of disorders in the circulatory system in the course of portal hypertension. It is characterized by impaired left ventricular systolic and diastolic dysfunction, and electrophysiological abnormalities, especially QT interval prolongation. However, signs and symptoms reported by patients are non-specific and include reduced exercise tolerance, fatigue, peripheral oedema, and ascites. The disease usually remains asymptomatic with almost normal heart function, unless patients are exposed to stress or exertion. Unfortunately, due to the subclinical course, CCM is rarely recognized. Orthotopic liver transplantation (OLTx) seems to improve circulatory function although there is no consensus about its positive effect, with reported cases of heart failure onset after transplantation. Researchers indicate a careful pre-, peri-, and post-transplant cardiac assessment as a crucial point in detecting CCM and improving patients’ prognosis. There is also an urgent need to update the CCM definition and establish a diagnostic algorithm for early diagnosis of CCM as well as a specific treatment of this condition.

The evaluation and monitoring of patients’ haemodynamic parameters are essential in everyday clinical practice. The application of continuous, non-invasive measurement methods is a relatively recent solution. CNAP, ClearSight and many other technologies have been introduced to the market. The use of these techniques for assessing patient eligibility before cardiac procedures, as well as for intraoperative monitoring is currently being widely investigated. Their numerous advantages, including the simplicity of application, time- and cost-effectiveness, and the limited risk of infection, could enforce their further development and potential utility. However, some limitations and contradictions should also be discussed. The aim of this paper is to briefly describe the new findings, give practical examples of the clinical utility of these methods, compare them with invasive techniques, and review the literature on this subject.