Biomedical subjects

H Akagi

Publications and source records attributed to H Akagi.

202 records · Page 12Linked to original sources

PubMedDate not supplied

Physiologic reactions of awake animals to an immediate switch from a pulsatile to nonpulsatile systemic circulation.

The purpose of this study is to clarify physiologic reactions to an immediate switch of flow pattern from pulsatile to nonpulsatile. A pulsatile ventricular assist device (VAD) was implanted in four 40-64 kg goats. Blood was drawn from the left atrium and ventricle and expelled into the aorta. After 2 weeks the VAD was quickly replaced by a centrifugal pump, MD-10 (Iwaki Pump, Tokyo, Japan), 760 g in weight and phi 70 mm x 84 mm in size, set on the back, without anesthesia. A 100% nonpulsatile bypass flow was immediately obtained, and the pump was set to maintain the same mean aortic pressure as before the switch; central venous pressure, cardiac output, systemic vascular resistance, oxygen consumption, blood lactate, plasma adrenalin, noradrenalin, renin activity, angiotensin II, and aldosterone were measured. Behavior of the goats did not change, and fluid infusion and higher cardiac outputs were not required. Most of the parameters did not deviate from control levels after the switch. In conclusion, a mammal immediately accommodates well to nonpulsatile flow.

Aldosterone↗

PubMedDate not supplied

A blood-liquid interface for prolonged extracorporeal oxygenation with excellent antithrombogenicity.

The authors verified the excellent antithrombogenicity of a blood-liquid interface (BLI) and introduced an oxygenator based on the principle of gas exchange across direct BLI. In a newly developed oxygenator, three layers of liquid flowed horizontally, contacting one another: O2 saturated silicone oil on the top, O2 saturated fluorcarbon at the bottom, and blood in the middle. Gas exchange was carried out across both direct BLIs. This system provided excellent antithrombogenicity as well as good gas exchange. The results indicate that this method will become a promising modality for prolonged extracorporeal oxygenation.

Blood Coagulation↗

PubMedDate not supplied

[Rest angina induced by coronary artery spasm at the first septal artery: a case report].

A 41-year-old man was admitted because of chest pain at rest. The exercise test and coronary angiography were performed after all antianginal medication was discontinued for 24 hours. During the graded treadmill exercise stress test using the Bruce protocol, the patient had anginal pain with the electrocardiogram (ECG) showing ST segment elevation in leads V1 and V2. A baseline coronary angiogram disclosed 50% stenosis of the first septal branch of the left coronary artery. After a bolus of 0.1 mg ergonovine was administered into the coronary artery, the patient complained of typical anginal pain. Complete occlusion of the first septal branch was demonstrated, associated with significant ST segment elevation in leads V1-V3, right bundle branch block, and electrical axis deviation to the left on the ECG. The coronary occlusion reversed soon after nitroglycerin administration into the coronary artery. We diagnosed a rare case of angina pectoris caused by spasm of the minor branch of coronary artery, and that serial ECG changes might demonstrate ventricular septal ischemia including the cardiac conduction system. ST segment elevation in leads V1-V3 indicated ischemia of the ventricular septum, and right bundle branch block, axis deviation to the left, and increased amplitude of the precordial R wave might be induced by ischemia of the right bundle branch, left anterior bundle branch and septal branch in the cardiac conduction system supplied by the septal branches of the left anterior descending coronary artery.

Adult↗

PubMedDate not supplied

An implantable left ventricular assist system with an electrical impedance monitoring and control system.

The authors developed an implantable left ventricular assist system (LVAS) for bridge to transplant of rather small sized adults. The pump was made of segmented polyether polyurethane and was 86 mm in diameter, 50 mm in height, with a 70 ml nominal stroke volume. A percutaneous drive line was connected with an external pneumatic control drive unit (CDU). In chronic animal experiments using 11 adult goats, the pump was installed between the LV apex and the descending aorta and was placed in the abdominal wall. Five goats were killed after 4 to 14 weeks while in good physical condition, and one is ongoing. There were no prominent thromboembolic symptoms despite no anti-thrombogenic agent being used. The new electrical impedance-based monitoring and control system (Z system) was installed in the CDU. In this Z system, automatic calibration was performed periodically for several seconds while the drive condition was changed to ensure full-fill of the blood pump. The full-fill to full-empty drive was well controlled by this Z system. In conclusion, the new Z system is practical and useful for monitoring and control of an implantable pump, giving this LVAS a promising place in clinical use.

Adult↗