Trigeminia de la bigeminia ventricular por mecanismo reentrante: reentrada de la reentrada / Trigeminy of ventricular bigeminy caused by reentrant mechanism: reentry of reentry

El proceso post-infarto agudo de miocardio genera el sustrato apropiado para la formación de circuitos de reentrada, los cuales son considerados como el mecanismo más frecuente de las extrasístoles y taquiarritmias ventriculares. Presentamos el trazado electrocardiográfico de un paciente con infarto agudo de miocardio en quien se observó la inusual concurrencia de una trigeminia ventricular acoplada a extrasístoles ventriculares bigeminadas, que originó una secuencia de trigeminia sobre la bigeminia, evidenciando la existencia de dos circuitos reentrantes (reentrada de la reentrada); después de una dupla de la extrasístole bigeminada se genera un aleteo ventricular.

The process that follows an acute myocardial infarction generates an appropriate substrate for the formation of reentry circuits, considered to be the most frequent mechanism of ventricular extrasystoles and tachyarrhythmias. We present the case of a patient with an acute myocardial infarction unusually concurring with ventricular trigeminy coupled to ventricular bigeminated extrasystoles giving rise to a trigeminy sequence over the bigeminy, which indicates the existence of two reentry circuits (reentry of reentry) that trigger ventricular flutter.

Ocular pressure waveform reflects ventricular bigeminy and aortic insufficiency.

Ocular pulse amplitude (OPA) is defined as the difference between maximum and minimum intraocular pressure (IOP) during a cardiac cycle. Average values of OPA range from 1 to 4 mmHg. The purpose of this investigation is to determine the source of an irregular IOP waveform with elevated OPA in a 48‑year‑old male. Ocular pressure waveforms had an unusual shape consistent with early ventricular contraction. With a normal IOP, OPA was 9 mmHg, which is extraordinarily high. The subject was examined by a cardiologist and was determined to be in ventricular bigeminy. In addition, he had bounding carotid pulses and echocardiogram confirmed aortic insufficiency. After replacement of the aortic valve, the bigeminy resolved and the ocular pulse waveform became regular in appearance with an OPA of 1.6–2.0 mmHg. The ocular pressure waveform is a direct reflection of hemodynamics. Evaluating this waveform may provide an additional opportunity for screening subjects for cardiovascular anomalies and arrhythmias.

Atropine-induced atrial bigeminy during general anesthesia in a Cocker Spaniel dog / 대한수의학회지

A 12-year-old female Cocker Spaniel (7.5 kg of body weight) was presented for resection of a mammary gland tumor. During surgery, the heart rate was remarkably decreased due to a second-degree type I atrioventricular block. Atropine (0.05 mg/kg) was administered to increase the heart rate. Although the heart rate was elevated, atrial bigeminy occurred and persisted until the dog fully recovered from general anesthesia. These results highlight the possibility of atrial bigeminy caused by atropine administration during anesthesia.

Implanting dual-chamber pacemaker through right thoracotomy to establish a canine tachycardia-mediated cardiomyopathy model / 第二军医大学学报

Objective To create a canine model of premature ventricular contraction-induced tachycardia-mediated cardiomyopathy, and to explore the effect of frequent premature ventricular contraction on the function of the left ventricular function. Methods Sixteen mongrel dogs were randomly divided into sham operation group and paced group. Animals in the paced group underwent the implantation of a dual-chamber pacemaker through right thoracotomy, and the pacemaker was connected to two epicardial right ventricular leads, with one creviced in the cardiac apex and the other one in the outflow tract of the right ventricle, with an atrioventricular delay adjusted to ensure the presence of coupled pacing to simulate ventricular bigeminy. Dogs in the control group were not connected to the leads. Echocardiographic measurements were obtained before and 4 weeks after operation. Results One dog in the paced group died of infection after 4 weeks. In the paced group (n = 7), LV end-diastolic diameter (LV-EDD) increased from (2. 86 ± 0. 10) cm before operation to (3. 35 ± 0. 27) cm after operation (P< 0. 05) and LV end-systolic diameter (LV-ESD) increased from (2. 07 ± 0. 20) cm before operation to (2. 72 ± 0. 21) cm after operation (P<0. 05). In addition, the left ventricular ejection fraction (LVEF) decreased from (67. 57 ± 4. 49)% before operation to (43. 66 ± 3. 88) % after operation (P<0. 05). No significant changes in LV dimensions or function were noted before and after operation in the control group. Conclusion It is feasible to simulate ventricular bigeminy with coupled pacing in canines. Premature ventricular contraction-induced cardiomyopathy can lead to increased LV dimensions and decreased LV.