High-density mapping of Koch's triangle during sinus rhythm and typical atrioventricular nodal re-entrant tachycardia, integrated with direct recording of atrio-ventricular node structure potential.

BACKGROUND: The mechanism of typical slow-fast atrioventricular nodal re-entrant tachycardia (AVNRT) and its anatomical and electrophysiological circuit inside the right atrium (RA) and Koch's Triangle (KT) are not well known. OBJECTIVE: To identify the potentials of the compact AV node and inferior extensions and to perform accurate mapping of the RA and KT in sinus rhythm (SR) and during AVNRT, to define the tachycardia circuit. METHODS: Consecutive patients with typical AVNRT were enrolled in 12 Italian centers and underwent mapping and ablation by means of a basket catheter with small electrode spacing for ultrahigh-density mapping and a modified signal-filtering toolset to record the potentials of the AV nodal structures. RESULTS: Forty-five consecutive cases of successful ablation of typical slow-fast AVNRT were included. The mean SR cycle length (CL) was 784.1 ± 6 ms and the mean tachycardia CL was 361.2 ± 54 ms. The AV node potential had a significantly shorter duration and higher amplitude in sinus rhythm than during tachycardia (60 ± 40 ms vs. 160 ± 40 ms, p < .001 and 0.3 ± 0.2 mV vs. 0.09 ± 0.12 mV, p < .001, respectively). The nodal potential duration extension was 169.4 ± 31 ms, resulting in a time-window coverage of 47.6 ± 9%. The recording of AV nodal structure potentials enabled us to obtain 100% coverage of the tachycardia CL during slow-fast AVNRT. CONCLUSION: Detailed recording of the potentials of nodal structures is possible by means of multipolar catheters for ultrahigh-density mapping, allowing 100% of the AVNRT CL to be covered. These results also have clinical implications for the ablation of right-septal and para-septal arrhythmias.

Cardiac complications of COVID-19 vaccination: now we know more.

The proliferation of good quality observational studies on the potential adverse effects of COVID-19 vaccination has greatly increased our knowledge on myocarditis and pericarditis, and also, more recently, on arterial hypertension. According to some recent studies, the incidence of a significant increase in blood pressure after COVID-19 vaccination is about 3.2% (95% CI: 1.62-6.21). The incidence of serious hypertensive emergencies or stage III hypertension has been reported as 0.6%. It is well known that the 'spike protein' of the Sars-CoV-2 virus, the synthesis of which is induced by vaccines, binds to ACE2 receptors, inducing their migration towards the inside of the cell. This would result in a lack of ACE2 activity on cell surfaces and therefore a relative deficiency of angiotensin1-7 with a relative excess of angiotensin II, which could explain, at least in part, the blood pressure increases. Regarding myo-pericarditis, there is evidence that the advantages of COVID-19 vaccination over non-vaccination remain preponderant in terms of prevented hospitalizations and serious complications of COVID-19, compared with the risk of developing myocarditis. In the age group most at risk of COVID-19 vaccine myocarditis (12-29 years), for every 100 000 vaccinated, compared to about four more cases of myocarditis we have 56 fewer hospitalizations, 13.8 admissions to intensive care and 0.6 fewer deaths. Several studies have shown that post vaccine myocarditis/pericarditis are generally short-lasting phenomena with favourable clinically course.

The myocardial bridge: incidence, diagnosis, and prognosis of a pathology of uncertain clinical significance.

The myocardial bridge (MB) is a common anomaly of the coronary tree, very often clinically silent. The artery typically involved is the left anterior descending in its proximal and/or middle portion. MB can cause ischaemia with various mechanisms, directly proportional to the degree of compression of the intra-myocardial tract, which impairs the coronary flow. It is a dynamic phenomenon that is affected by the adrenergic tone and is therefore often brought by physical exercise. MB, when symptomatic, often begins with angina from exertion; some patients have more severe conditions such as unstable angina or myocardial infarction. Coronary vasospasm related to MB-induced endothelial dysfunction can explain a number of cases that come to observation even with catastrophic pictures such as ventricular fibrillation caused by ischaemia. The diagnostic workup includes the non-invasive study using computed tomography angiography and the invasive study of the haemodynamic impact using pressure and Doppler guides. In symptomatic cases, drug therapy with a beta-blocker is enough to manage angina. When it fails, there is the option of coronary angioplasty or surgical treatment techniques.

Inadvertent Lead Malposition in the Left Heart during Implantation of Cardiac Electric Devices: A Systematic Review.

BACKGROUND: The inadvertent lead malposition in the left heart (ILMLH) is an under-recognized event, which may complicate the implantation of cardiac electronic devices (CIEDs). METHODS: We investigated the clinical conditions associated with ILMLH and the treatment strategies in these patients. We made a systematic review of the literature and identified 132 studies which reported 157 patients with ILMLH. RESULTS: The mean age of patients was 68 years, and 83 were women. ILMLH was diagnosed, on average, 365 days after CIEDs implantation. Coexisting conditions were patent foramen ovale in 29% of patients, arterial puncture in 24%, perforation of the interatrial septum in 20%, atrial septal defect in 16% and perforation of the interventricular septum in 4%. At the time of diagnosis of ILMLH, 46% of patients were asymptomatic, 31% had acute TIA or stroke and 15% had overt heart failure. Overall, 14% of patients were receiving anticoagulants at the time of diagnosis of ILMLH. After diagnosis of ILMLH, percutaneous or surgical lead extraction was carried out in 93 patients (59%), whereas 43 (27%) received anticoagulation. During a mean 9-month follow-up after diagnosis of ILMLH, four patients experienced TIA or stroke (three on oral anticoagulant therapy and one after percutaneous lead extraction). CONCLUSION: ILMLH is a rare complication, which is usually diagnosed about one year after implantation of CIEDs. An early diagnosis of ILMLH is important. Lead extraction is a safe and effective alternative to anticoagulants.