Masaru Hoshina

Inhalation of nebulized nitroglycerin in dogs with experimental pulmonary hypertension induced by U46619

Abstract Background: Pulmonary hypertension (PH) causes mortality in some congenital and acquired heart and lung diseases. However, inhalation of NO gas requires complicated and expensive instruments and elaborate preparations to avoid toxic gas administration. We tested the effectiveness and safety of inhaled nebulized nitroglycerin (Neb‐NTG) in dogs with experimental PH.

Hemodynamic Effect of the Ventricular Pacing Site in Fetal Lambs with Complete Atrioventricular Block

SHIRAISHI, H., et al. Hemodynamic Effect of the Ventricular Pacing Site in Fetal Lambs with Complete Atrioventricular Block. Complete atrioventricular (AV) block in hydrops fetalis is associated with high mortality. Fetal ventricular pacing to restore ventricular rate can be an effective procedure, however, no fetal data has shown an appropriate epicardial ventricular pacing site. To evaluate the hemodynamic effect of right and left ventricular pacing in fetal lambs with complete AV block, a fetal complete AV block model was created. Aortic pressure, central venous pressure, and QRS duration were measured, and right and left ventricular output was estimated in seven fetal lambs. The uterus was opened under maternal anesthesia, and under local anesthesia, catheters were inserted into the fetal superior vena cava and ascending aorta through a neck incision. Pacing leads were then sutured onto the fetal right and left ventricular epicardium via a midline thoracotomy. Complete AV block was created by cryoablation of the AV node. Ventricular output was estimated using echocardiography by a transuterine approach. Fetal hemodynamics were observed before AV block creation (control), and after complete AV block creation with the right and left ventricular pacing set at 150/min. The right ventricular output was 320 ± 66 mL/kg per minute at control, decreased to 243 ± 65 mL/kg per minute during right ventricular pacing (P < 0.05), and was 254 ± 61 mL/kg per minute during left ventricular pacing. The left ventricular output was 224 ± 98 mL/kg per minute at control, 176 ± 77 mL/kg minute during right ventricular pacing, and 178 ± 67 mL/kg per minute during left ventricular pacing. Biventricular (combined ventricular) output was 544 ± 134 mL/kg per minute at control, 419 ± 114 mL/kg per minute during right ventricular pacing, and 432 ± 100 mL/kg minute during left ventricular pacing. Systolic aortic pressure was 62.2 ± 8.7 mmHg at control, 55.2 ± 9.5 mmHg during right ventricular pacing, and 53.4 ± 9.1 mmHg during left ventricular pacing. Central venous pressure (CVP) was 2.6 ± 0.5 mmHg at control, 4.0 ± 2.7 mmHg during right ventricular pacing, and 4.4 ± 2.5 mmHg during left ventricular pacing. The QRS duration was 51 ± 54 ms at control, but lengthened to 87 ± 19 ms during right ventricular pacing and to 78 ± 21 ms during left ventricular pacing (P < 0.05). In conclusion, the right ventricular output decreased during right ventricular pacing in fetal lambs with complete AV block, while it was preserved during the left ventricular pacing. Left ventricular pacing might be superior for treating hydropic fetuses with complete AV block.

Volume measurement of a pediatric ventricular phantom model using three-dimensional echocardiography

PurposeVolume measurement of the ventricle is necessary to evaluate cardiac function. Accurate volume measurement of the ventricle by three-dimensional (3D) echocardiography will mark a new step in pediatric cardiovascular diagnosis and treatment. We studied volume measurement of a pediatric ventricular model using 3D echocardiography.MethodsThe ultrasonic diagnostic setup used in this study comprised a Philips Sonos 7500 ultrasound system with an electronic sector probe of a ×4 matrix phased array transducer. The ventricular model was made from a latex surgical glove. The tip of the third finger of the glove was cut off and fixed to a manifold. The ventricular model was gently placed in a reservoir filled with water. Volumes of physiological saline solution ranging from 2 ml to 50 ml in 2-ml increments were injected into the ventricular model and examined. Twenty-five ultrasound images of the ventricular model were obtained using 4D Cardio View RT 1.2 software.ResultsThere was excellent correlation and agreement between the injected volumes and the calculated volumes (Y = −0.539 + 1.005X, r = 0.997, four cut plane; Y = −0.191 + 1.006X, r = 0.997, eight cut plane). Thus, accurate volume measurement of the ventricular model by 3D echocardiography was confirmed.ConclusionsOur study demonstrated that 3D echocardiography is highly accurate for volume measurement in a pediatric ventricular model (for volumes of 2 to 50 ml) under static conditions.

Left Atrial Tachyarrhythmia in Fetal Lambs

SHIRAISHI, H., et al.: Left Atrial Tachyarrhythmia in Fetal Lambs. To evaluate the hemodynamic effect of rapid left atrial pacing on fetal circulation, a fetal supraventricular tachyarrhythmia model was made and the aortic pressure, central venous pressure, and left and right ventricular outputs were measured in ten fetal lambs. Under maternal anesthesia, the uterus was opened, and under local anesthesia, catheters were inserted into the fetal superior vena cava and ascending aorta through a neck incision. Pacing leads were then sutured onto the fetal left atrial appendage via left thoracotomy. Ventricular output was estimated using echocardiography by a transuterine approach. Fetal hemodynamics were observed without pacing (control), and at the pacing rates of 200, 300, 350, and 400/min. The aortic pressure decreased when the left atrium was paced at 300/min or more and the central venous pressure increased when the left atrium was paced at 350/min or more. The left and right ventricular outputs decreased when the left atrium was paced at 350/min or more. The left ventricular output was 215 ± 54 mL/kg per minute at control, 205 ± 60 mL/kg minute when paced at 200/min, 178 ± 58 mL/kg per minute when paced at 300/min, but decreased to 164 ± 44 mL/kg per minute when paced at 350/min and to 149 ± 57 mL/kg per minute when paced at 400/min. The right ventricular output was 338 ± 66 mL/kg per minute at control, 336 ± 95 mL/kg per minute when paced at 200/min, 273 ± 91 mL/kg per minute when paced at 300/min, but decreased to 256 ± 80 mL/kg per minute when paced at 350/min and to 202 ± 76 mL/kg per minute when paced at 400/min. Fetal circulatory failure was initially confirmed when the left atrium was paced at 300/min in this left atrial tachyarrhythmia model.