Neurometric evaluation of epileptic children who do well and poorly in school.
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Adolescent↗
Biomedical subjects
H Ahn
Publications and source records attributed to H Ahn.
Percutaneous fenestration of aortic dissection: salvage of an ischemic solitary left kidney.
The false channel of a type III aortic dissection caused acute renal ischemia by compression of the origin of the left renal artery in a patient with status post-right nephrectomy. To relieve the ischemia and restore renal function, percutaneous balloon fenestration was performed successfully.
Aortic Dissection↗
In vivo experiment leading to clinical application of an electrohydraulic ventricular assist device with magnetic coupling.
We developed an electrohydraulic ventricular assist device with magnetic coupling. The integrated system consists of a blood pump, a water conduit for pressure transmission, a bellows type pumping sac, an actuator for transforming the circular motion of a motor to the linear motion of a pusher plate attached to the pumping sac with magnetic coupling, and a controller. The purpose of the coupling was to prevent excessive sucking against the atrial wall. Number 21 Medtronic Hall (Irvine, CA) mechanical valves were used in the inflow and outflow ports of the blood pump. Maximum dynamic stroke volume was 48 ml, and against a mean afterload of 100 mm Hg, maximum pump output was 7 L/min. Chronic in vivo experiments were performed in three sheep, and during these evaluations the system showed no noticeable problems related to mechanical or electronic devices. When left atrial pressure decreased below 0 mm Hg, the magnetic coupling system decoupled the pumping sac and pusher plate with satisfactory reliability. The device was clinically applied in a postoperative patient with chronic dilating cardiomyopathy, and no significant device related problems ensued. These results prove that the electrohydraulic ventricular assist system with magnetic coupling is a suitable ventricular assist device.
Animals↗
Analysis of the interventricular pressure waveform in the moving-actuator total artificial heart.
Right and left filling pressures are important parameters in the automatic control of a total artificial heart (TAH) within normal physiologic ranges. Our TAH is composed of a moving actuator, right and left ventricles, and an interventricular space (IVS) enclosed by a semirigid housing. During operation of the TAH, the IVS volume is changed dynamically by the difference between the ejection volume of one ventricle and the inflow volume of the other. We measured the interventricular pressure (IVP) waveform by using a pressure sensor and analyzed the relationship between the IVP and the preload condition. From in vitro and in vivo experiments, we found that the measured filling pressures were linearly related to the negative peak value of the IVP. Additionally, we found that we could use the time interval from actuator start to the positive peak value of the IVP (outflow valve opening) as a useful parameter to estimate the blood filling volume of the diastole ventricle.
Animals↗
Nicardipine hydrochloride injectable phase IV open-label clinical trial: study on the anti-hypertensive effect and safety of nicardipine for acute aortic dissection.
We performed a multicentre, phase IV, open-label clinical trial to examine the clinical usefulness of a continuous infusion of nicardipine hydrochloride to control hypertension in 31 patients with acute aortic dissection. Target blood pressure levels were reached within 15 min in 16 patients; in 15-30 min in 10 patients; in 30-45 min in three patients; and in 45-60 min in two patients. Baseline average systolic, diastolic and mean arterial blood pressures were 147 +/- 23 mmHg, 82 +/- 18 mmHg and 104 +/- 18 mmHg, respectively, with third-day pressures significantly reduced at 119 +/- 12 mmHg, 69 +/- 9 mmHg and 86 +/- 8 mmHg. Blood pressures after discontinuation of the infusion were not significantly different from those measured on the third day of infusion and no definite adverse effects attributable to the treatment were observed. Nicardipine hydrochloride was both effective and safe at controlling blood pressure in patients with acute aortic dissection.
Antihypertensive Agents↗
A tether-free, moving actuator total artificial heart.
An electromechanical moving-actuator TAH was developed and implanted for 5 days in a calf experiment. The efficiency and durability were further improved using pendulous motion of the actuator. This new pendulum pump has a circular motion produced by gear mechanisms connected to the motor. It has a height (from valves to housing bottom) of 7 cm and centrally directed inlets and outlets for good fittability. Active filling (-10 mmHg) inside inner blood sacs was produced by the suction effects of the outer sacs attached to a moving actuator. Two acute animal experiments were performed using the pendulum pump with a Coridale sheep (50 kg weight), and a male calf (70 kg weight). A test was made of 30 minutes of tether-free operation of the implanted pendulum pump inside the small chest of the calf. The pump shows the engineering feasibility of the implantable electrical TAH inside a human chest cavity.
Animals↗
Intraoperative assessment of blood flow and tissue viability in small-bowel ischemia by laser Doppler flowmetry.
Laser Doppler flowmetry (LDF) was used for intraoperative assessment of blood flow and tissue viability in 23 patients with small-bowel ischemia, and the signal levels in ischemic bowel were compared with previously obtained reference values from normal ileum and jejunum. The average LD signal was 6.8 +/- 2.9 V in nonischemic bowel, 0.3 +/- 0.2 V in segments with macroscopically irreversible ischaemia and 2.1 +/- 1.2 V in segments with clinically uncertain viability. In 12 cases with strangulated bowel it was possible, following LDF, to avoid resecting nine of ten bowel segments with clinically uncertain viability. In four of the six patients with mesenteric vascular occlusion, LDF indicated that clinical judgement had underestimated the extent of severe ischemia. Among the five cases of iatrogenic ischemia there was one failure, with postoperative irreversible ischemia and anastomotic leakage. LDF is concluded to be a useful method for intraoperative assessment of intestinal blood flow in patients with small-bowel ischemia and it provides substantial information on tissue viability affecting surgical strategy.
Adolescent↗