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Following new concepts by Bichat in the early 19th century, of organic and animal life centered around the ganglionic nervous system, over 100 years of anatomic studies and physiologic experimentation eventually resulted in Gaskell's 1916 book entitled "The Involuntary Nervous System" and Langley's 1921 book entitled "The Autonomic Nervous System." Neurology and cardiology emerged as specialties of medicine in the early 20th century. Although neurology made several prominent discoveries in neurophysiology during the first half of the 20th century, cardiology developed coronary care units and cardiac catheterization in the 1960s. Programmed electrical stimulation of the heart and noninvasive ambulatory monitoring provided new methodologies to study clinical cardiac arrhythmias. Experimentally, direct cardiac nerve stimulation of sympathetic nerve endings, as well as parasympathetic control of the atrioventricular node, provided the background to new detailed autonomic studies of the heart. Neurocardiology, perhaps initially more directed towards our understanding of sudden cardiac death, ultimately embraced an even significantly more complex scheme of local circuit neurons and near-endless loops of interconnecting neurons in the heart. Intrathoracic extracardiac and intracardiac ganglia have been recharacterized, both anatomically and physiologically, laying the groundwork for potential new therapies of cardiac neuromodulation., (© 2024 Wiley Periodicals LLC.)

Following the development of permanent transvenous cardiac pacing in the 1960s, the costs of pacemakers quickly led to their reuse in both developed countries and in low-and middle-income countries (LMIC). Legal, ethical, and industrial factors gradually resulted in the termination of reuse in developed countries. Without health care budgets to pay for costly pacemaker technologies, nongovernmental organizations (NGOs), and other groups have provided support to physicians and hospitals treating patients with heart block in LMICs. Multiple other academic and private groups have also assisted such patients in LMICs. Pacemaker companies have provided physicians and hospitals with new devices (that have an expired package date or through charitable donations). Greater care of preparing and cleaning refurbished devices have demonstrated overwhelmingly the safety and effectiveness of reused devices. More recently, cardiac resynchronization therapy and implantable cardioverter-defibrillators have also been reused in patients in LMICs. While the globalization of noncommunicable diseases continues, patients with rhythm disorders in LMICs can no longer be left behind. While patients in developed countries only receive new devices to treat rhythm disorders, the practice of reused cardiac implantable electronic devices will expand in LMICs, until equal access to device technologies be made available to all., (© 2022 Wiley Periodicals LLC.)

Introduction: Patients with cardiac arrhythmias are generally instructed to avoid caffeine intake. A comprehensive evaluation of the electrophysiological effects of caffeine on atrial and ventricular tissues in humans has not previously been performed., Methods and Results: Eighty patients (31 men, mean age 49 ± 14 years) with symptomatic supraventricular tachycardia (SVT) undergoing an electrophysiologic study (EPS) prior to catheter ablation were randomized to receive oral caffeine or placebo. Caffeine at a dosage of 5 mg/kg (moderate intake) or placebo tablets were administered orally at a mean time of 57 ± 13 minutes prior to the EPS. The median (IQR) caffeine level in patients receiving caffeine was 7.4 μg/mL (4.7-8.7), as compared with 0.15 (0.00-0.61) in patients receiving placebo, P < 0.0001. Caffeine was associated with a significant increase in resting systolic and diastolic blood pressures as compared with placebo, while the resting heart rate was not significantly different between both groups. Caffeine was not associated with significant effects on the effective refractory period of the atrium or ventricle, as well as on AV node conduction. SVT was induced in all but 3 patients; there was no significant difference between groups receiving placebo or caffeine on SVT inducibility or the cycle length of induced tachycardias., Conclusions: Caffeine, at moderate intake, was associated with significant increases in systolic and diastolic blood pressures, but had no evidence of a significant effect on cardiac conduction and refractoriness. Furthermore, no effect of caffeine on SVT induction or more rapid rates of induced tachycardias was found., (© 2014 Wiley Periodicals, Inc.)

Unlabelled: Psychological Adjustment and Fidelis ICD Leads. , Introduction: Implantable cardioverter defibrillators (ICD) advisory notices present treatment dilemmas for physicians and patients. On one side, the risk of device malfunction and the likely severity of clinical sequelae have to be estimated. This estimate has to be weighed against the risks of surgery to replace the advisory component. It is unclear whether there is important psychological morbidity associated with living with an ICD under advisory and whether this should be factored into decision making. The study had 2 objectives: (1) to examine whether there is adverse psychological adjustment when an ICD is under advisory, and (2) to assess the psychological sequel of advisory ICD component malfunction., Methods: This study focused on the Sprint Fidelis advisory. All patients in our practice who still had an in service Medtronic Fidelis lead were included in the study. Three groups were compared: advisory group but no fracture (n = 249), advisory group with lead fracture (n = 24), and a control group (n = 143). For both objectives, we used a general anxiety and depression instrument and also device-specific measures of psychological well being., Results and Conclusions: First, there was no evidence of differences in the psychological functioning of patients at risk of ICD lead malfunction compared to a control group. Second, patients who had experienced an ICD lead fracture had adverse psychological morbidity compared to control patients, and this appeared, primarily, to be related to receiving inappropriate shock(s) at the time of the fracture., (© 2010 Wiley Periodicals, Inc.)

Background: The three-dimensional contributions to human atrial activation in sinus rhythm have not been specifically characterized. We evaluated the sequence of endocardial and epicardial activation and voltage of the atria during normal sinus rhythm., Methods and Results: The study group includes 35 patients with history of symptomatic atrial fibrillation. Prior to catheter ablation of atrial fibrillation, we performed multielectrode electroanatomic mapping during sinus rhythm, endocardially of the RA, LA, and coronary sinus (CS) and, in 10 patients, epicardially of the transverse sinus and oblique sinus. Following activation of the atrial region of the sinus node, the epicardial transverse sinus was activated 11 +/- 18 msec later, while the earliest endocardial LA activation occurred in the region of Bachmann's bundle at 31 +/- 13 msec, significantly earlier than the earliest epicardial LA activation of the oblique sinus at 54 +/- 10 msec (P < 0.002). The posterior LA revealed complex types of activation in 66% of patients analyzed, due to the convergence of wavefront propagation from the CS, oblique sinus, and endocardial LA. Bipolar voltage measurements revealed significantly higher values for the epicardium (mean 3.05 +/- 1.31 mv) than for the endocardium (mean 1.65 +/- 0.75 mv), P < 0.0001 between both groups., Conclusions: In sinus rhythm, we have characterized endocardial and epicardial atrial activation and voltage, and provide an analysis and understanding of the genesis of the P wave complex in humans.

Percutaneous radiofrequency ablation of pulmonary vein potentials has been shown to eliminate atrial fibrillation in a subset of patients characterized by frequent and repetitive paroxysms of atrial fibrillation. However, pulmonary vein disconnection has had only limited success at curing patients with persistent atrial fibrillation. In those patients, left atrial substrate modification and linear ablation strategies have had substantially higher success rates. Furthermore, in other patients, elimination of right atrial triggers (superior vena cava) or modification of right atrial substrate has been required for elimination of atrial fibrillation. Finally, the realization that the coronary sinus is a third atrial chamber that can both initiate and maintain atrial fibrillation has provided new understanding to the pathogenesis of atrial fibrillation. From a clinical perspective, only careful anatomic and mapping strategies specifically aimed at each subset of patients with atrial fibrillation will allow for pattern recognition and establish which mechanisms are responsible for initiation and maintenance of atrial fibrillation. Only the latter will allow for increased long-term success rates of ablation of atrial fibrillation.