Kozo Suma

OPTIMAL HEART RATE IN CARDIAC PACING IN CORONARY SCLEROSIS AND NON-SCLEROSIS

The main objects of cardiac pacing are to secure the best hemodynamic condition of the patient and to provide the greatest possible comfort. During longterm pacing of patients with atrioventricular block, we have learned that the greatest comfort is provided by adjusting the pacing rate to an arbitrary frequency which is termed the “optimal rate” and which varies from patient to patient. Our interest centered around the atrial rate because it was thought that hemodynamic conditions reflected upon the atrial rate. On the basis of clinical observations, hemodynamic studies, and subjective complaints from patients, we concluded that the optimal rate in ventricular pacing is obtained by making the atrial rate minimal. A comparison was made of the optimal rates thus set for patients with coronary sclerosis and non-sclerosis. Usually, the optimal pacing rate was determined as a range. This is explained by the theoretical analysis of our “circulatory function curve.”

Changes in diastolic regional stiffness of the left ventricle before and after coronary artery bypass grafting

SummaryTo evaluate the effect of coronary artery bypass grafting (CABG) on regional diastolic function of the left ventricular wall, we applied the concept of the stiffness constant to the diastolic σ-ln (1/H) relation, where σ is the mean wall stress, and H is the wall thickness of the region of concern, and ln (1/H) is the natural logarithm of the reciprocal of wall thickness. We assessed 12 cardiac regions in six patients with coronary artery disease who underwent CABG at the Cardiovascular Hospital of Central Japan between May 1994 and January 1995. Left ventricular pressure and regional wall thickness were measured simultaneously, with a micromanometer-tipped catheter and by twodimensional echocardiography, respectively, before and after CABG. The stiffness constant (K) was obtained by fitting the diastolic σ-ln (1/H) data points to an exponential curve with zero asymptote: σ = Cexp[Kln (1/H)]. Preoperatively, the stiffness constant in the affected region (CABG region) was greater than that in the unaffected region (non-CABG region) (4.79 ± 2.56 vs 2.95 ± 0.72). Postoperatively, the stiffness constant in the CABG region was significantly decreased, to 3.21 ± 1.22. The stiffness constant, which is derived from the σ-ln (1/H) relation, is useful for the assessment of LV regional diastolic function.

Clinical Performance of Microporous Polypropylene Hollow-Fiber Oxygenator

A newly developed polypropylene hollow-fiber oxygenator was used from June 1979, to July, 1980, in 100 patients undergoing open-heart operation. Adequate oxygenation and carbon dioxide elimination were observed throughout perfusion in spite of a relatively low ratio of oxygen flow to blood flow. Plasma hemoglobin level was maintained low after long hours of perfusion. There were no complications related to the oxygenator during or after the operation. Because of its highly efficient performance as well as small size and easy handling, this oxygenator is being used routinely during open-heart procedures in our hospital.

Development of a New Circulatory Assist Method with the Combined Effects of Intra-Aortic Balloon Pumping and Counter Pulsation-First Report

Current circulatory assist methods, such as intra-aortic balloon pumping (IABP), are not always adequate to save acute circulatory failure patients. Therefore, a stronger, percutaneously accessible method is required. We found that the combination of IABP and CP generated a profound circulatory assist effect, and we have consequently developed a new assist system in this study. A sac type blood pump with a volume of 20 ml and a single port without a valve, was developed for CP. In the mock circulatory test, a 20 ml stroke volume was obtained using a cannula with a 5 mm diameter under the following driving conditions: air pressure = 200/-100 mmHg; S/D = 50%; pulse rate = 100 bpm. In vivo experiments were performed using four mongrel dogs with body weights of 12-20 kg. A cannula for CP was inserted via the brachial artery or subclavian artery into the aortic root. The pump flow (PF), coronary artery flow (CF), renal arterial flow (RF), and aortic pressure (AP) were measured, and the combined effects of IABP and CP were compared with their individual effects. In the most effective case, a marked increase in diastolic AP (60%), cardiac output (40%), and CF (100%) was obtained by the combination of IABP and CP, which produced a remarkable effect compared with the single use of IABP and CP. There was no negative effect on RF by this assist method. As this new circulatory support system has many circulatory assist effects, and is percutaneously accessible, it will be available for clinical use.

Postoperative deep body temperature rhythm.

The postoperative deep body temperature rhythms of fifteen patients who received aorto-coronary bypass surgery (group I), and of seven patients who received non-cardiac major surgery (group II), were studied. Postoperative patients, especially those who received aortocoronary bypass surgery, showed greatly disturbed deep body temperature rhythm. There existed infradian and ultradian rhythm in both groups, and there existed two patients in group I who did not show sinusoidal rhythm. The patients of group I also showed a longer period of rhythm than did those of group II. The mesor and amplitude of the patients in group I showed a greater individual variation than did those in group II. The acrophase of both groups deviated widely. The patients who underwent cardiac surgery needed a longer time for temperature rhythm recovery than did those who underwent general surgery.

Removal of trypsin complexed alpha-2 macroglobulin by plasma fractionation.

Ischemia-reperfusion injury in open heart surgery can cause atherosclerotic changes in both bypass grafts and native coronary arteries by increasing endothelial permeability and allowing excessive influx of LDL into the subendothelium. The authors used LDL apheresis during cardiopulmonary bypass (CPB) to actively remove serum LDL before reperfusion, minimizing LDL influx. They evaluated the efficacy and safety of this new procedure in eight hypercholesterolemic patients. The control group consisted of 41 patients. Mean LDL cholesterol (LDL-C) level on admission was 180 +/- 41 (SD) in the LA group and 139 +/- 32 mg/dl in the control group (p = 0.02). After 105 +/- 27 min of apheresis, the LDL-C level in the LA group decreased to 62 +/- 25 mg/dl (reduction rate: 59 +/- 18%). In contrast, in the control group, the LDL-C level was reduced to 117 +/- 41 mg/dl (reduction rate: 16 +/- 9.5% [P = 0.0001]) after CPB. No significant difference was observed in intraoperative blood loss, postoperative blood loss, platelet count, prothrombin time, activated partial thromboplastin time, incidence of wound complications, or early patency rate of bypass graft between groups. Low density lipoprotein apheresis during CPB is a safe and effective method for lowering serum LDL level sufficiently before reperfusion, and can adequately reduce LDL influx into the vessel wall.Ischemia-reperfusion injury in open heart surgery can cause atherosclerotic changes in both bypass grafts and native coronary arteries by increasing endothelial permeability and allowing excessive influx of LDL into the subendothelium. The authors used LDL apheresis during cardiopulmonary bypass (CPB) to actively remove serum LDL before reperfusion, minimizing LDL influx. They evaluated the efficacy and safety of this new procedure in eight hypercholesterolemic patients. The control group consisted of 41 patients. Mean LDL cholesterol (LDL-C) level on admission was 180 +/- 41 (SD) in the LA group and 139 +/- 32 mg/dl in the control group (p = 0.02). After 105 +/- 27 min of apheresis, the LDL-C level in the LA group decreased to 62 +/- 25 mg/dl (reduction rate: 59 +/- 18%). In contrast, in the control group, the LDL-C level was reduced to 117 +/- 41 mg/dl (reduction rate: 16 +/- 9.5% [P = 0.0001]) after CPB. No significant difference was observed in intraoperative blood loss, postoperative blood loss, platelet count, prothrombin time, activated partial thromboplastin time, incidence of wound complications, or early patency rate of bypass graft between groups. Low density lipoprotein apheresis during CPB is a safe and effective method for lowering serum LDL level sufficiently before reperfusion, and can adequately reduce LDL influx into the vessel wall.

Evaluation of Pump Performance of a Percutaneous-Type Pulsatile Left Ventricular Assist Device (MAD Type 5 and Type 6)

We have been developing a percutaneous-type left ventricular assist device named the Modified Assist Device (MAD). The system is composed of an air-driven sac-type blood pump and cannula in which an inflow and an outflow valve have been installed. With the MAD type 5, a maximum pump flow of 2.51/min was obtained in a mock circulation study. For clinical application of this ventricular assist device, a new model, MAD type 6, was developed and was evaluated in in vitro and in vivo experiments. To obtain satisfactory anatomical fit and durability, a spiral was installed in the cannula of MAD type 6. In in vitro evaluation, the pressure gradients across the inflow and outflow valves were 110 mmHg and 75 mmHg at a flow rate of 21/ min. With the MAD type 6, the index of hemolysis was almost the same as that of a centrifugal pump. The durability test was maintained for more than 30 days without deterioration of the new system. In an animal experiment, using dogs, more effective systolic unloading and diastolic augmentation were observed by the activation of the MAD type 6 than with an intra-aortic balloon pump (IABP) assist. As for the peripheral circulation, the MAD type 6 device produced greater carotid artery flow than did the the IABP assist. In conclusion, the MAD type 6, a pulsatile-flow device, appears to have a design and function suitable for clinical application.

Development of A New Catheter Combined with Angioscope, Ultrasonic Transducer and Laser fiber

血管内視鏡、血管内超音波一体型 レーザー心 血管内手術装置の検討 今 西 薫1)、 井 街 宏2)、 阿 部 裕 輔2)、 須 磨 幸 蔵2) 東京女子医科大学付属第二病院心臓血管外科1) 東京大学医学部医用電子研究施設2) Development of A New Catheter Combined with Angioscope,Ultrasonic Transducer and Laser fiber Kaoru Imanishi, Kou Imachi, Yusuke ABE, Kozo Suma Department of Cardiovascular Surgery, Tokyo Womens Medical College Daini Hospital1) Institute of Medical Electronics, Faculty of Medicine, University of Tokyo2)

Intraoperative Assessment of the Corrective Surgery of Tetralogy of Fallot

Postoperative prognosis of the patient with tetralogy of Fallot is highly dependent upon residual stenosis of the outflow tract from the right ventricle. A grade of residual stenosis was not morphologically as shown in Fig. I but hydrodynamically measured to assess necessity of subsequent reoperation for relieving residual stenosis and postoperative care.

LASER ANGIOPLASTY SYSTEM USING CONTACT CERAMIC TIP: STABILIZATION OF POWER AND DEVELOPMENT OF ENDOSCOPEPIC SYSTEM

LASER ANGIOPLASTY SYSTEM USING CONTACT CERAMIC TIP: STABILIZATION OF POWER AND DEVELOPMENT OF ENDOSCOPIC SYSTEM Y. Abe, K. Imanishi, T. Yonezawa, T. Chinzei *, I. Sogawa *, M. Suzukawa, K. Mabuchi, K. Imachi, A. Kouno, T. Ono, T. Tago *, K. Atsumi and I. Fujimasa Institute of Medical Electronics, Faculty of Medicine, University of Tokyo. *RCAST We have been developing laser angioplasty system using contact ceramic tip. In order to stabilize the required power for plaque ablation, ceramic coating tip was designed and developed by implanting metal at the point of the surface of ceramic tip, and the special endoscope with 7F size was designed and developed from the points of percutaneous approach and ceramic tip usage. The laser probe was designed to be separated at the part of laser fiber and able to be inserted from the top of the endoscope. The special endoscope and laser probe with ceramic coating tip were very useful for atheroma ablation inside the aorta of atherosclerotic rabbits under the visual field. The required power for plaque ablation with ceramic coating tip was 515W, and was able to be stabilized.