Localized Pulmonary Vein Scar Promotes Atrial Fibrillation in High Left Atrial Pressure

BackgroundPulmonary vein (PV) ablation is unsuccessful in atrial fibrillation (AF) patients with high left atrial (LA) pressure. Increased atrial stretch by increased pressure is proarrhythmic for AF, and myocardial scar alters wall deformation. We hypothesized that localized PV scar is proarrhythmic for AF in high LA pressure.MethodsRadiofrequency energy was delivered locally in the right PV of healthy sheep. The sheep recovered for 4 months. Explanted hearts (n = 9 PV scar, n = 9 controls) were perfused with 1:4 blood:Tyrode’s solution in a four-chamber working heart setup. Programmed PV stimulation was performed during low (∼12 mmHg) and high (∼25 mmHg) LA pressure. An AF inducibility index was calculated based on the number of induction attempts and the number of attempts causing AF (run of ≥ 20 premature atrial complexes).ResultsIn high LA pressure, the presence of PV scar increased the AF inducibility index compared with control hearts (0.83 ± 0.20 vs. 0.38 ± 0.40 arb. unit, respectively, p = 0.014). The diastolic stimulation threshold in high LA pressure was higher (108 ± 23 vs. 77 ± 16 mA, respectively, p = 0.006), and its heterogeneity was increased in hearts with PV scar compared with controls. In high LA pressure, the refractory period was shorter in PV scar than in control hearts (178 ± 39 vs. 235 ± 48 ms, p = 0.011).ConclusionLocalized PV scar only in combination with increased LA pressure facilitated the inducibility of AF. This was associated with changes in tissue excitability remote from the PV scar. Localized PV ablation is potentially proarrhythmic in patients with increased LA pressure.

ARTHUR MARTYNOVYCH KANGER – ASSISTANT MANAGER OF THE SCIENTIFIC AND FORENSIC EXAMINATION CABINET AT THE PROSECUTOR OF THE ODESA COURT CHAMBER (to the 145th anniversary of his birthday and the 60th anniversary of his death)

The article is devoted to the main stages of life and activity of Professor Artur Martinovich Kanger (1875-1960) – pharmacist, forensic chemist, criminologist and teacher. The main attention is paid to his work as an assistant to the head of the Cabinet of Scientific and Forensic Expertise under the Prosecutor of the Odesa Court Chamber. Working in this institution for eight years (1914-1922), he held the position of assistant manager of the Cabinet, and in recent years headed the Forensic Department. He has hundreds of chemical expertise, including studies of explosives, gunpowder, poisons, etc. In addition, chemical methods were used in the study of handwriting and ink research, forgery of documents made by mechanically. In particular, during 1922, Professor A. M. Kanger and his closest assistant laboratory assistant Shettle I. H. conducted 215 chemical examinations. In most cases, chemical analysis methods were used in the research. However, in addition to this method, others were used: microscopic analysis, physical methods (for example, determination of specific gravity) and photographic methods. It is noteworthy that a significant part fell on the study of objects that were material evidence in cases of counterfeiting paper banknotes. Along with work at the Odesa Cabinet of Scientific and Forensic Expertise, Professor A. M. Kanger was a rector of Odesa Institute of Chemical and Pharmaceuticals (1921-1922) and at the same time headed the Department of Pharmaceutical and Forensic Chemistry. At the beginning of 1923 Arthur Martynovych Kanger together with his wife and young son went to Riga. Working in scientific and educational institutions, he made a significant contribution to the formation of the state system of scientific and forensic exspertise in Latvia and contributed to the development of criminalistics in the German Democratic Republic (GDR).

Improvement of Structural and Technological Parameters of the Innovative Type Climate Chamber

While studying the influence of the parameters, characterizing heat removal from the working medium of the chamber, on operational characteristics of the experimental installation, the values of the amperage supplied to the thermoelectric module were being varied from 1.4 to 4.2 A, as well as the degree of chamber adiabaticity was being altered by changing the number of extruded polystyrene foam plates 20 mm thick in the build-up chamber cover from one to 3. The dynamics of the working medium temperature change depending on the amperage supplied to the thermoelectric module is illustrated by graph dependencies. As a result of data processing by constructing the second order orthogonal central composition plan the adequate regression equation was received for the cooling process and the thermo stating of the climate chamber working medium and the conclusion on a rational number of the chamber cover plates (which equals 3) was made. It was found out that upon increasing the amperage supplied to the thermoelectric module and using a three-plate cover the experimental chamber working medium temperature is varied from –2ºC to 11ºC, this can be applied for cooling and thermo stating various objects including biological raw materials of both animal and plant origin as well as non-food objects.

Effects of ATP administration on isolated swine hearts: Implications for ex vivo perfusion and cardiac transplantation

Cardiac transplant outcomes can be compromised by the effects of global ischemia and associated reperfusion injury. In attempts to alleviate these phenomena, various pharmaceutical agents can be administered. Previous reports have shown that adenosine triphosphate (ATP) may act as either a postconditioning (PoC) or supplementary (Sup) therapy with cardiosupportive benefits. To further evaluate ATP’s relative effectiveness, we used an isolated swine heart four-chamber working model to monitor both hemodynamic and metabolic responses. We employed two strategies of ATP administration: (1) a postconditional (PoC) bolus just prior to reanimation, and (2) regular dosing throughout the assessment period (Sup). Ex vivo swine hearts in the Sup group elicited significantly higher left ventricular function during the 2 h monitoring period than controls. In contrast, PoC administration appeared to induce depressed cardiac function. The effects of ATP on cardiac function can have varied effects, dependent on when it is administered. Impact statement We employed an isolated swine heart four-chamber working model to investigate two potential strategies for adenosine triphosphate (ATP) administration as an ex vivo therapy: (1) application of a single bolus dose during reperfusion (postconditioning or PoC), and (2) repeated bolus dosing throughout the experiment (supplementary or Sup). Ex vivo swine hearts in the Sup group elicited significantly higher left ventricular function during the 2 h experimental monitoring period. In contrast, ATP administration in the PoC group appeared to induce a degree of depressed hemodynamic function. These data suggest varied functional roles of ATP administration relative to their use in ex vivo perfusion strategies. We consider that both treatment strategies, if appropriately administered and with further investigation of dosing paradigms, may eventually elicit value in various clinical scenarios, including heart transplantation and ex vivo heart perfusion to assess potential organs for transplantation and potentially increase the pool of viable donor hearts.

Time Variate Comparison of In Situ and In Vitro Monophasic Action Potential Recordings

Monophasic action potentials (MAPs) have long been used as a means to study the focal electrical activity of the myocardium. [1, 2] Upon the application of adequate contact force, the signals provide important insights into focal depolarization and repolarization, activation timing, and focal arrhythmic behaviors. [3–6] Within our laboratory we have developed an isolated physiologic, four-chamber working, large mammalian heart model (the Visible Heart® methodology) to study cardiac devices and their interactions with the myocardium. [7] Through the use of a modified Krebs-Henseleit buffer, we can uniquely visualize the device-tissue interface: in this study, the placement of catheters. The purpose of this study was two-fold. First, we demonstrated the long term stability of MAP recordings in an in situ swine model. Second, we showed the relationship between MAPs recorded from in vitro and in situ preparations of each specimen.