Naoki Sakakibara

Surgical Treatment of Congenital Coronary Artery Fistulas: 27 Years' Experience and a Review of the Literature

Abstract Background and aim of the study: A congenital coronary artery fistula (CAF) is a relatively rare congenital anomaly and is defined as an abnormal direct communication between any coronary artery and any of the cardiac chambers. This article reviews our experience over the past 27 years, as well as other literature, and discusses the surgical indications and methods relating to CAF. Methods: From 1973, 25 patients aged from 2 to 69 years underwent surgical treatment for congenital CAF. Seventeen patients were diagnosed as isolated CAF. All patients under 19 years of age with isolated CAF were asymptomatic. Twenty fistulas originated from the left coronary artery and 9 from the right. The pulmonary artery was the most dominant drainage site. Four patients among the isolated CAF cases were surgically treated without a cardiopulmonary bypass. Results: All patients were discharged from hospital without any perioperative complications. Postoperative coronary angiography was done on all patients with only one slightly residual CAF flow. The average follow‐up time was 9.6 years and all patients were asymptomatic and doing well. Conclusions: Definitive surgical correction is safe and effective, with good results. Therefore, it should be considered even in asymptomatic patients because of the risk of future complications.

Therapeutic angiogenesis with intramyocardial administration of basic fibroblast growth factor

BACKGROUND Basic fibroblast growth factor (bFGF) induces endothelial cell and smooth muscle cell proliferation and stimulates angiogenesis. This study was designed to evaluate the effects of intramyocardial administration of bFGF on myocardial blood flow, angiogenesis, and ventricular function in a canine acute infarction model. METHODS Myocardial infarction was induced in 12 dogs by ligation of the left anterior descending coronary artery. Within 5 minutes after coronary occlusion, 100 microg of human recombinant bFGF in 1 mL of saline was injected into the infarct and border zone in 6 dogs, whereas saline alone was used in 6 control dogs. Myocardial blood flow was determined with colored microspheres before and immediately after coronary ligation and again 3, 7, 14, and 28 days after treatment and it was expressed as percent of normal. Angiogenesis was evaluated by immunohistochemical studies 28 days later. Cardiac function was evaluated by repeated echocardiographic measurement. RESULTS Treatment with bFGF significantly increased the endocardial blood flow in the border zone (7 days after infarction, 75%+/-7% and 41% +/-7% in the bFGF and control groups, respectively, p<0.01) as well as epicardial blood flow in the infarcted zone. Treatment with bFGF significantly increased the capillary density (39.7+/-2.3 and 22.7+/-1.1 vessels per visual field in the bFGF and control groups, respectively, p<0.01) as well as arteriolar density in the border zone. Treatment with bFGF significantly reduced the change in ratio of thickness of the infarcted wall to the normal wall (44%+/-6% and 26% +/-5% in the bFGF and control groups, respectively, p<0.05). It improved the left ventricular ejection fraction (7 days after infarction, 0.54+/-0.02 and 0.37+/-0.03 in the bFGF and control groups, respectively, p<0.01). CONCLUSIONS Intramyocardial administration of bFGF increased the regional myocardial blood flow, reduced thinning of the infarcted region, and improved ventricular function in acute myocardial infarction. Intramyocardial administration of bFGF may be a new therapeutic approach for patients with acute myocardial infarction.

Effect of low-dose aprotinin on coagulation and fibrinolysis in cardiopulmonary bypass.

To study the effect of low-dose aprotinin on hemostasis in patients undergoing cardiopulmonary bypass (CPB) for coronary artery bypass operations and to elucidate the mechanism of aprotinin action, we randomized 14 of 27 patients to receive 30,000 KIU/kg aprotinin in the CPB priming volume and 7,500 KIU/kg aprotinin intravenously each hour during CPB (1 patient was excluded from the aprotinin group because of protamine shock). Intraoperative and postoperative blood loss was significantly reduced in the aprotinin group. Antithrombin III level was significantly decreased, and the levels of thrombin-antithrombin III complexes were significantly increased during CPB in both groups, indicating activation of the clotting system. The marked increase in fibrin(ogen) degradation products during CPB in the control group, indicating enhanced fibrinolytic activity, was significantly reduced in the aprotinin group. alpha 2-Plasmin inhibitor was significantly reduced during CPB in the control group. The marked increase in alpha 2-plasmin inhibitor-plasmin complexes in the control group, indicating plasmin activity, was significantly reduced in the aprotinin group. A marked decrease in the platelet count was observed during CPB similarly in both groups. These findings demonstrated that low-dose aprotinin administration was effective in reducing intraoperative and postoperative blood loss and that activation of the clotting system during CPB was not followed by hyperfibrinolysis in aprotinin-treated patients. The improved hemostasis is mainly attributable to the prevention of hyperfibrinolysis during CPB.

Is internal thoracic artery grafting suitable for a moderately stenotic coronary artery

Abstract Grafting an internal thoracic artery to a coronary artery with moderate stenosis remains controversial. Competitive flow from the native coronary artery has been proposed as the cause of distal narrowing and ultimate failure of the internal thoracic artery graft. We investigated intraoperative phasic blood flow in internal thoracic arteries grafted to coronary arteries with various degrees of stenosis and the influence of stenosis on postoperative angiographic findings. One hundred patients who underwent coronary artery bypass grafting of an internal thoracic artery to the left anterior descending coronary artery were divided into three groups according to degree of coronary stenosis. Group 1 included 39 patients who had 75% or less stenosis, group 2 included 34 patients with stenosis from 76% to 90%, and group 3 included 27 patients with stenosis greater than 90%. Mean flow and peak systolic flow of internal thoracic artery graft in group 1 were lower than those in group 2 ( p p p

Pressure characteristics in arterial grafts for coronary bypass surgery

The haemodynamic properties of arterial grafts were studied by measuring the pressure waveform at the tip of the grafts in 28 patients who underwent coronary artery bypass surgery (CABG). The internal thoracic and gastroepiploic arteries were harvested as pedicles for CABG. Pressure wave of the ascending aorta and arterial grafts were simultaneously recorded with an electrocardiogram under stable haemodynamic conditions before cardiopulmonary bypass. Systolic, diastolic and mean pressures were measured, and mean systolic and diastolic pressures calculated for systolic and diastolic areas divided by time. The ascending aorta showed high sustained diastolic pressure that decreased gradually. Pressures in the internal thoracic and gastroepiploic artery grafts had narrow contours and decreased rapidly. Pressure waveforms in the internal thoracic and gastroepiploic artery grafts had a notch between the systolic and diastolic contours. There was no difference in systolic pressure between the ascending aorta and internal thoracic and gastroepiploic artery grafts. Diastolic pressures were 64(9), 55(7), and 51(6) mmHg in the ascending aorta and internal thoracic and gastroepiploic artery, respectively. Mean(s.d.) pressures were 75(9), 65(9) and 59(7) mmHg in the ascending aorta and internal thoracic and gastroepiploic artery grafts, respectively. Diastolic and mean pressures in the internal thoracic artery grafts were significantly lower than in the ascending aorta but significantly higher than in the gastroepiploic artery grafts. The mean(s.d.) calculated diastolic pressure in the internal thoracic artery grafts was significantly lower than in the ascending aorta but significantly higher than in the gastroepiploic artery grafts. The inferior capacity of flow through the arterial grafts may be mainly attributable to reduced diastolic pressure, which is caused by anatomical characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Internal thoracic artery graft function during exercise assessed by transthoracic Doppler echography.

BACKGROUND Noninvasive quantitative assessment of internal thoracic artery (ITA) graft function at rest and during exercise is important in patients who have undergone coronary artery bypass grafting. METHODS Blood flow in the ITA graft was measured using transthoracic color Doppler echography before and after operation in 50 patients who underwent coronary artery grafting using an ITA to the left anterior descending artery. The patients were divided into three groups according to the degree of coronary stenosis and previous anterior myocardial infarction: Group 1 included 12 patients with severe (90% or more) coronary stenosis accompanied by anterior infarction. Group 2 included 26 patients with severe coronary stenosis without anterior infarction. Group 3 included 12 patients with moderate (75% or less) coronary stenosis without anterior infarction. Transthoracic echographic images of the ITA were obtained through the first intercostal space using a 7.5-MHz probe, and the diameter and cross-sectional area of the ITA were measured on B-mode imaging. Systolic, diastolic, and mean blood flow velocity and volume were measured by the Doppler method. RESULTS Internal thoracic artery diameter increased significantly from 2.2 mm to 2.4 mm after operation. The ITA flow patterns in both flow velocity and volume changed from systolic-dominant to diastolic-dominant after operation. Postoperative ITA graft flow was 82 +/- 24 mL/min, 53 +/- 30 mL/min, and 31 +/- 15 mL/min (p < 0.01, group 1 versus 3; p < 0.05, group 1 versus 2) and percent diastolic fraction of ITA flow was 72%, 68%, and 62% (not significant) in groups 1, 2, and 3, respectively. Compared with intraoperative ITA flow, which was measured using an ultrasound transit-time flowmeter, postoperative ITA graft flow was increased in group 1, but not changed in group 2 or 3. The ITA graft flow was measured before and after exercise in 19 patients and was compared with ITA flow in 10 normal control subjects. The ITA graft flow increased significantly with exercise in all patients in the three groups. Percent diastolic fraction of ITA flow increased significantly with exercise in patients with severe coronary stenosis (groups 1 and 2), but decreased significantly in patients with moderate stenosis (group 3). CONCLUSIONS Changes in native coronary artery and ITA graft may be predicted by assessing ITA flow pattern during exercise. Transthoracic color Doppler echography is a clinically useful noninvasive method of assessing ITA graft function at rest and during exercise.

Flow capacities of arterial grafts for coronary artery bypass grafting

The flow capacities of arterial and saphenous vein grafts in 100 patients who had coronary artery bypass grafting were compared under exercise conditions by continuous ventricular function monitoring, which records serial beat-to-beat radionuclide data and calculates left ventricular ejection fractions every 20 seconds. Ejection fraction profiles during graded bicycle exercise were divided into four types. In type A, the ejection fraction continued to increase. In type B, the ejection fraction initially increased, but decreased during the late exercise stage. In type C, the ejection fraction did not change. In type D, the ejection fraction continued to decrease throughout exercise. A decrease in ejection fraction, observed in type B or D, is an early indicator of myocardial ischemia. Before operation, 10 patients showed type A, 30 type B, 11 type C, and 49 type D responses. After operation, 68 patients showed type A, 21 type B, and 11 type C responses. Patients were divided into three groups according the type of bypass graft. Group 1 included 21 patients with two arterial grafts and vein grafts; group 2, 61 patients with an internal thoracic artery graft and vein grafts; group 3, 18 patients with only vein grafts. All of the grafts were patent on angiography. Eight patients (38%) in group 1 and 13 (21%) in group 2 showed a postoperative type B response, but none of the patients in group 3 had a postoperative type B response (p < 0.02). Seven of 8 patients in group 1 with postoperative type B responses had only arterial grafts to the left-side coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental and clinical evaluation of a noninvasive reflectance pulse oximeter sensor

The objective of this study was to evaluate a new reflectance pulse oximeter sensor. The prototype sensor consists of 8 light-emitting diode (LED) chips (4 at 665 nm and 4 at 820 nm) and a photodiode chip mounted on a single substrate. The 4 LED chips for each wavelength are spaced at 90-degree intervals around the substrate and at an equal radial distance from the photodiode chip. An optical barrier between the photodiode and LED chips prevents a direct coupling effect between them. Near-infrared LEDs (940 nm) in the sensor warm the tissue. The microthermocouple mounted on the sensor surface measures the temperature of the skin-sensor interface and maintains it at a preset level by servoregulating the current in the 940-nm LEDs. An animal study and a clinical study were performed. In the animal study, 5 mongrel dogs (weight, 10–20 kg) were anesthetized, mechanically ventilated, and cannulated. In each animal, arterial oxygen saturation (SaO2) was measured continuously by a standard transmission oximeter probe placed on the dogs earlobe and a reflectance oximeter sensor placed on the dogs tongue. In the first phase of the experiment, signals from the reflectance sensor were recorded while the dog was immersed in ice water until its body temperature decreased to 30°C. In the second phase, the animals body temperature was normal, and the oxygen content of the ventilator was varied to alter the SaO2. In the clinical study, 18 critically ill patients were monitored perioperatively with the prototype reflectance sensor. The first phase of the study investigated the relationship between local skin temperature and the accuracy of oximeter readings with the reflectance sensor. Each measurement was taken at a high saturation level as a function of local skin temperature. The second phase of the study compared measurements of oxygen saturation by a reflectance oximeter (SpO2[r]) with those made by a co-oximeter (SaO2[IL]) and a standard transmission oximeter (SpO2[t]). Linear regression analysis was used to determine the degree of correlation between (1) the pulse amplitude and skin temperature; (2) SpO2(r) and SaO2(IL); and (3) SpO2(t) and SaO2(IL). Studentst test was used to determine the significance of each correlation. The mean and standard deviation of the differences were also computed. In the animal study, pulse amplitude levels increased concomitantly with skin temperature (at 665 nm,r=0.9424; at 820 nm,r=0.9834;p<0.001) and SpO2(r) correlated well with SaO2(IL) (r=0.982; SEE=2.54%;p<0.001). The results of the clinical study are consistent with these findings. The proto-type reflectance pulse oximeter sensor can yield accurate measurements of oxygen saturation when applied to the forehead or cheek. It is, therefore, an effective alternative to transmission oximeters for perioperative monitoring of critically ill patients.

Physiologic characteristics of coronary artery bypass grafts

To investigate the hemodynamic characteristics of arterial grafts for coronary artery bypass grafting, we measured phasic pressure and flow patterns in three types of grafts in a canine model (n = 18). A graft from the ascending aorta (AAG), a graft from the descending aorta at the first lumbar level (DAG), analogous to a right gastroepiploic artery, and an internal thoracic artery (ITA) were anastomosed to each other. The composite graft was anastomosed to the left anterior descending coronary artery, and then the left anterior descending coronary artery was ligated. Before grafting, the AAG showed high sustained diastolic pressure, but the ITA and DAG showed rapid fall of diastolic pressures. Mean diastolic pressures were 83 +/- 2, 72 +/- 3, and 57 +/- 2 mm Hg in the AAG, ITA, and DAG (p < 0.05). Free flow in the AAG was markedly greater than in the ITA or the DAG. After grafting to the left anterior descending coronary artery, no changes were observed in diastolic pressures compared with the pregrafting values. Total blood flows were 72 +/- 6, 80 +/- 7, 57 +/- 7, and 44 +/- 6 mL/min in the left anterior descending coronary artery, AAG, ITA, and DAG, respectively. There were no differences in systolic graft flow between the three types of grafts. Diastolic blood flow in the ITA (29 +/- 4 mL/min) and DAG (18 +/- 3 mL/min) was smaller than in the AAG (48 +/- 4 mL/min) (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary bypass flow during use of intraaortic balloon pumping and left ventricular assist device

BACKGROUND Intraaortic balloon pumping (IABP) and left ventricular assist device (LVAD) are used for left ventricular support when low cardiac output occurs after a coronary bypass operation for serious coronary artery disease. There are hemodynamic differences in blood flow in various kinds of coronary artery bypass grafts, caused by their inherent physiologic characteristics. The hemodynamic effects of left ventricular assistance with IABP and LVAD on blood flow through various coronary artery bypass grafts were investigated. METHODS An ascending aorta-coronary bypass graft (ACB), an internal thoracic artery, and a descending aorta-coronary bypass graft were anastomosed to the left anterior descending coronary artery in a canine model. In this experimental model, the blood flow to the same coronary bed in the three types of grafts could be evaluated. Blood flow in the left anterior descending coronary artery through the three types of coronary bypass grafts was studied in this model during or in the absence of ventricular assistance. RESULTS In the control study, the systolic blood flow did not differ among the three types of grafts, but the diastolic flow decreased in the following order: with the ACB, the internal thoracic artery, and the descending aorta-coronary bypass graft. The systolic flow during IABP and LVAD was similar to the control flows. Use of IABP increased the diastolic flow by 75.3%+/-12.4% of the control value in the ACB, 37.9%+/-25.0% in the internal thoracic artery, and 21.2%+/-11.4% in the descending aorta-coronary bypass graft. The LVAD increased the diastolic flow by 97.7%+/-18.7% of the control value in the ACB, 64.5%+/-25.7% in the internal thoracic artery, and 63.0%+/-27.9% in the descending aorta-coronary bypass graft. The diastolic blood flows in the left anterior descending coronary artery and the three types of grafts were significantly greater with IABP than the control values, and significantly greater with LVAD than with IABP and the control values. The degrees of increase of diastolic flows in the left anterior descending coronary artery and the ACB with IABP and LVAD were significantly greater than in the arterial grafts (p < 0.01). CONCLUSIONS The diastolic flows in the internal thoracic artery and descending aorta-coronary bypass graft increased less than in the native left anterior descending coronary artery and ACB during left ventricular assistance, particularly with IABP. It is important for the selection of tactics for the management of catastrophic status after coronary bypass grafting to consider the hemodynamic characteristics of the graft.