Biomedical subjects
Publications and source records attributed to M H Hwang.
Four selected cases of emergent IABP insertion in PV patients are presented. After angiographic documentation of critical iliac stenosis, conservative peripheral angioplasty was performed prior to IABP insertion. No patient experienced a peripheral ischemic event associated with IABP use.
A "sandwich" technique employing steel coils and gelfoam embolization was applied in two cases of hepatic artery aneurysms. Immediate cessation of the bleeding was evident clinically and the post-embolization angiogram showed occlusion of the vascular lesion. Cholecystectomy is one of the most common abdominal operations and it is generally well tolerated, particularly in young and middle-aged patients. Morbidity rates of 5% to 32% and mortality rates of 0.4% to 2.5% have been reported, depending on such factors as age, underlying illness, etc. (1-4). The most frequent complications of cholecystectomy are wound infection, abscess, ductal injury or ligation, and bleeding. This paper describes two cases of hepatic pseudoaneurysm following iatrogenic damage during cholecystectomy which was treated with transarterial embolization.
Myocardial ATP, ADP, and AMP were measured from cardiac biopsy in 11 dogs after intracoronary injection of 6 mL of sodium-meglumine diatrizoate (SMD), iohexol (IOH), or 0.9% sodium chloride (NaCl), and in three of the dogs at baseline before any injection. The ATP at baseline and after SMD, IOH, and 0.9% NaCl were 5.39 +/- 0.41, 3.72 +/- 0.70, 5.52 +/- 0.82, and 5.44 +/- 1.40 mumol/g wet weight, respectively. There were significant differences between SMD and IOH (P less than .02), and between SMD and 0.9% NaCl (P less than .05). The energy charge of SMD was 0.82 +/- 0.08, which differed from 0.89 +/- 0.02 for NaCl or 0.9 +/- 0.05 for baseline (P less than .05), but not from 0.85 +/- 0.04 for IOH. In conclusion, diatrizoate caused significant depletions in ATP stores in comparison with iohexol, but there was no significant difference with respect to energy charge. Nonionic contrast media would be preferable for coronary arteriography in patients whose high-energy stores might be depleted from severe ischemia.
Hemodynamic changes due to intracoronary injections of nonionic contrast medium Omnipaque-350 (OM), ionic dimer Hexabrix (HB), and ionic contrast medium Renografin-76 (R76) were compared at baseline and during reperfusion after a 30-minute left anterior descending coronary artery (LAD) occlusion. In 11 open chest, anesthetized, and atrially paced dogs, 4 ml of either OM, HB, R76, or 0.9% NaCl were injected into the carotid-LAD bypass system. Coronary blood flow (CBF) and coronary vascular resistance (CVR) were measured before, during and after the intracoronary injection. The maximal hyperemic change (in percentage) from the preinjection value of CBF and CVR were calculated. The results at baseline and during reperfusion for CBF were: 104 +/- 14% vs. 85 +/- 10% for OM (NS); 76 +/- 11% vs. 39 +/- 9% for R76 (p less than 0.05); 57 +/- 8% vs. 33 +/- 5% for HB (P less than 0.05); and 30 +/- 7% vs. 9 +/- 4% for 0.9% NaCl (p less than 0.05). Consequently, the hyperemic changes of CVR at baseline and during reperfusion were: -49 +/- 3 vs. -42 +/- 4% for OM (NS); -44 +/- 3% vs. -24 +/- 6% for R76 (p less than 0.01); -36 +/- 3% vs. -24 +/- 4% for HB (p less than 0.05); and -18 +/- 4% vs. -7 +/- 3% for 0.9% NaCl (p less than 0.05). Thus, ischemia and reperfusion significantly dampened the coronary hemodynamic and vascular response to R76, HB, and 0.9% NaCl but not to OM. The preserved coronary vascular reserve with high flow in this canine post-ischemic reperfusion model may explain the advantage of nonionic over ionic contrast media used in emergency coronary angiography following thrombolysis.
An external fixation device that allows limited motion of the wrist joint without disruption of the anatomic alignment was used for the articular Colles' fractures in this study. From July 1985 to April 1989 during a 45-month period, 87 patients with 90 articular Colles' fractures (three cases with bilateral involvement) were treated with a modified dynamic external skeletal device after a closed reduction in full supination of the forearm. Excellent anatomic reduction near 91% of the sound wrist as well as satisfactory functional results around 90.5% of the sound wrist were gained during the 24-month follow-up period. Forearm muscles exert compression forces on distal radial metaphyseal fractures throughout the healing period. Any procedure or device that cannot provide constant counterforce to the action of forearm muscles during fracture healing will result in the loss of anatomic reduction. Adequate distraction counter-force was provided by an external fixation device that was superior to other conventional methods because of its simple application, low rate of complications, and excellent anatomic and functional results.
To investigate the local effect of heparin on blood clot formation and partial thromboplastin time (PTT), blood was withdrawn into the catheters filled with iopamidol and heparin at 0, 1, 2, 3, 5, and 10 U per ml concentrations as debubbling. After 30 min incubation, blood clotting was observed in all 8 experiments with heparin concentrations of 0 and 1 U per ml; in 3 of 8 with 2 U per ml; and in none with greater than or equal to 3 U per ml. PTT of blood and contrast mixture in catheters increased significantly when heparin concentrations were increased from 2 to 3 U per ml and reached a level of greater than 110 sec at 5 or more U per ml. Thus, the addition of heparin to nonionic contrast media at concentrations of 5 U per ml may be an easy measure with which to prevent blood clotting and reduce thromboembolic complications during coronary arteriography.
Repeat coronary angiography was performed in 42 patients 10 years after randomization to medical (n = 21) or surgical (n = 21) therapy for chronic angina. The native coronary arteries were classified into 15 angiographic segments and 3 arterial trunks for analysis of progression of coronary artery disease. The incidence rate of disease progression in coronary segments was 24% and 28% in medically and surgically treated patients, respectively (p = NS). Grafted segments showed a 38% rate of disease progression, which was higher than the 18% rate of for nongrafted segments (p less than 0.001) and the overall rate of 24% for medically treated patients (p less than 0.01). Similarly, 29 (94%) of 31 grafted arteries exhibited disease progression compared with 19 (59%) of 32 nongrafted arteries (p less than 0.01) and 42 (67%) of 63 arteries in medically treated patients (p less than 0.01). In grafted vessels, disease progression occurred more often in arteries proximal (84%) to the anastomosis than in arteries distal (16%) to graft insertion (p less than 0.001). Progression occurred in 46% of proximal segments compared with 23% of distal segments (p less than 0.02). Progression was seen in 23 (55%) of 43 segments with an occluded graft compared with 30 (31%) of 96 segments with a patent graft (p less than 0.02). Ten years after randomization, medically and surgically treated patients showed a comparable rate of disease progression in coronary segments. However, surgical therapy appeared to significantly accelerate atherosclerotic progression in the grafted vessels, especially in the proximal portions. Occluded grafts also correlated with an adverse effect on disease progression.(ABSTRACT TRUNCATED AT 250 WORDS)
Hemangiomas are uncommon primary tumors of the heart. Most of them are found incidentally at autopsy, during clinical evaluation, or cardiac surgery. Occasionally, a protean clinical picture is manifested, including valvular disorder, arrhythmias, obstruction of coronary artery and other significant vasculature, pericardial effusion, and embolic phenomena. Catheterization, angiography, and echocardiography all play some important role in the antemortem diagnosis of this cardiac tumor. The treatment of choice is simple complete excision. In this review, we add our experience with cardiac hemangiomas: one incidentally discovered at autopsy and another found during coronary artery bypass surgery.
To investigate the relationship between clot formation and thromboembolism, canine blood was withdrawn into catheter-syringe or catheter-steerable wire systems containing either contrast medium or normal saline as used in debubbling techniques. The contrast media used were iohexol, iopamidol, ioxaglate, and diatrizoate. Without the use of heparin, after a 30-minute incubation, blood clots were harvested from all catheter-syringe systems except those with diatrizoate and from all catheter-steerable wire systems. Significantly more blood clot was harvested from the catheter-steerable wire system. With use of heparinized blood, no clot was found in any system. Twelve dogs that underwent coronary angiography were divided into two groups; one received heparin (5,000 IU) and the other did not. Thromboembolism occurred in all nonheparinized dogs that underwent angiography with iohexol or iopamidol but not in any other group. The authors found that in a dog model nonionic contrast media are more thrombogenic than ionic contrast media, especially in the catheter-steerable wire system. The blood clot in the catheters is associated with thromboembolism during angiography. The authors maintain that in this setting, blood clotting and thromboembolism with nonionic agents can be eliminated with heparin.
A sixty-three-year-old patient with malignant histiocytic lymphoma of the heart presented with both superior vena cava syndrome and cardiac tamponade. A two-dimensional echocardiogram showed a large tumor mass in the right atrium and pericardial effusion with right ventricular compression. Superior and inferior vena cavagrams disclosed a lobulated tumor located in the right atrium that extended into and obstructed the superior vena cava. After the pericardial effusion was drained and the diagnosis was established, the patient was irradiated and given chemotherapy with resolution of the tamponade and superior vena cava obstruction.
To investigate the effect of sodium on cardiac hemodynamics, sodium chloride was added to nonionic contrast media to a 0.9% concentration and was compared with the standard media iohexol, iopamidol, and ioversol. Left coronary angiography was performed in 10 closed-chest, atrial-paced dogs with 10 ml injections of each preparation in a randomized and blinded fashion. The maximum changes in left ventricular systolic pressure, mean aortic pressure, left ventricular and diastolic pressure, and maximal rise of left ventricular pressure were measured. The left ventricular systolic pressure and mean aortic pressure decreased by 17 +/- 7 mm Hg and by 12 +/- 5 mm Hg with iohexol plus 0.9% NaCl, but only by 5 +/- 4 mm Hg and by 4 +/- 3 mm Hg with iohexol alone (p less than 0.001). The left ventricular and end diastolic pressure increased by 2.2 +/- 0.6 mm Hg with iohexol plus 0.9% NaCl, but did not change with iohexol alone (p less than 0.001). Left ventricular dp/dt decreased by 204 +/- 161 mm Hg/sec with iohexol plus 0.9% NaCl but increased by 392 +/- 122 mm Hg/sec with iohexol alone (p less than 0.001). Similar results were obtained from experiments with iopamidol versus iopamidol plus 0.9% NaCl and ioversol versus ioversol plus 0.9% NaCl. Ioversol plus 5% dextrose or ioversol plus 2.1% choline chloride (isomolar to ioversol plus 0.9% NaCl) produced a significant increase in left ventricular systolic pressure and left ventricular dp/dt (versus ioversol plus 0.9% NaCl, p less than 0.001). Thus, sodium, but not the osmolality or chloride, contributed to the negative inotropic effect of the contrast media.(ABSTRACT TRUNCATED AT 250 WORDS)
Contrast media occasionally produce bradyarrhythmias defined as a 25% decrease in heart rate and/or developing atrioventricular block during coronary angiography. Twelve left coronary angiographies and seven right coronary angiographies were performed with 10 ml of diatrizoate meglumine and diatrizoate sodium (Renografin-76 [R76] or Hypaque [H76]) or iopamidol (Isovue 370 [ISO]) in a blinded randomized fashion. Heart rate decreased significantly from 135 +/- 5 to 120 +/- 5 beats/min (p less than 0.001) with R76, to 127 +/- 7 beats/min (p less than 0.01) with H76, and to 130 +/- 6 beats/min (p less than 0.05) with ISO in left coronary angiographies; more profound decrease was observed in right coronary angiographies from 134 +/- 4 to 87 +/- 18 beats/min (p less than 0.001) with R76, to 99 +/- 14 beats/min (p less than 0.001) with H76, and to 125 +/- 7 beats/min (p less than 0.01) with ISO. In 12 left coronary angiographies bradyarrhythmia was observed in five cases with R76, two with H76, and none with ISO. In seven right coronary angiographies it occurred in six with R76, three with H76, and none with ISO. The differences in the incidence of bradyarrhythmia between R76 and ISO were significant during left and right coronary angiographies (p less than 0.05 and p less than 0.01, respectively). Thus ionic contrast media produced more marked bradyarrhythmias than nonionic contrast media in coronary angiography, especially R76. Right coronary angiography resulted in more profound bradyarrhythmias than left coronary angiographies. This study suggested that nonionic contrast media (ISO) might be preferable to ionic contrast media (R76 or H76) for coronary arteriography.
The hemodynamic effects induced by coronary angiography in dogs with low osmolar ionic dimer Hexabrix (HB) and nonionic Omnipaque-350 (OM) were compared to the standard ionic contrast medium, Hypaque-76 (H76), both in the normal heart and in one with simulated severe cardiac disease. Left coronary angiography was performed in 12 "normal" closed-chest dogs with 10-cc injections of H76, HB, and OM in a randomized, blinded fashion. The maximal change in the left ventricular (LV) systolic pressure (SP), mean aortic pressure (MAP), left ventricular end diastolic pressure (LVEDP), and LV dp/dt were recorded. The LVSP and MAP fell 30 +/- 3 mm Hg and 26 +/- 4 mm Hg with H76, 22 +/- 2 mm Hg and 19 +/- 2 mm Hg with HB, and 7 +/- 1.5 mm Hg and 5 +/- 1 mm Hg with OM (P less than .001). The LVEDP increased 4.8 +/- 0.5 mm Hg with H76, 3 +/- 0.5 mm Hg with HB, but only 0.2 mm Hg with OM (P less than .001). The LV dp/dt decreased 392 +/- 63 mm Hg/sec with H76 and 235 +/- 21 mm Hg/sec with HB, but increased 411 +/- 50 mm Hg with OM (P less than .001). In eight additional open-chest dogs, left coronary angiography was performed 1 hr after occlusion of the proximal LAD coronary artery and in the presence of a critical circumflex coronary artery (CX) stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)
The influence of contrast media on coagulation has an important association with thromboembolic complication during coronary angiography. In this study, whole blood was methodically mixed with nonionic contrast medium, Iohexol (IOH), conventional ionic contrast medium, Hypaque-76 (H76), and low osmolar ionic dimer Hexabrix (HB) in vitro. The thrombotic propensity of contrast agents can be evaluated by measuring the clot formation of the mixtures. The experiments were repeated with whole blood after systemic heparinization. In the in vitro study, 5 ml of canine (N = 10) and 3 ml of human (N = 11) whole blood was incubated for 30 min in glass tubes with equal volumes of IOH, H76, HB, and 0.9% NaCl before heparinization. Clot formation with IOH and 0.9% NaCl were seen both in dogs (4.0 +/- 0.7 gm and 5.6 +/- 0.8 gm) and in patients (1.4 +/- 0.9 gm and 2.9 +/- 1.3 gm), whereas no clot was seen with H76 or XB. Following heparinization, no clot was visualized in any mixture of whole blood with contrast media or 0.9% NaCl. Similar results were observed in the catheter-syringe system with canine blood (N = 11) mixed with the contrast agents. Blood clots found in 15 min and 30 min of IOH were 0.07 +/- 0.08 gm and 0.44 +/- 0.20 gm (P less than 0.01) and of NaCl were 0.29 +/- 0.37 gm and 0.69 +/- 0.38 gm (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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Ventricularization of pressure during coronary angiography has been said to identify the presence of left main coronary artery disease, but the hemodynamic features and the mechanism of this process have not been studied. Twenty consecutive patients with ventricularization were identified prospectively in our laboratory. Four patients had a discrete ostial left main stenosis and 16 patients had stenosis of the entire length of the left main coronary artery. The degree of pressure drop upon cannulation of the diseased left main coronary artery was highly variable; the systolic pressure decreased by 9 to 94 mm Hg, and the diastolic pressure decreased by 6 to 60 mm Hg. The morphology of the ventricularized pressure was distinct. It had a presystolic deflection resembling an a wave. The upstroke of this waveform was slower and the downstroke was steeper than that of the aortic pressure. An identical waveform was observed in dogs after partial occlusion of the left main coronary artery with a balloon-tipped catheter. The waveform of the so-called ventricularized pressure is derived from the aortic pressure, which is altered by its transmission across the left main coronary stenosis. The appearance of ventricularization is an important clue to the presence of left main coronary artery disease.
Endoscopic sphincterotomy (EST) was performed in 53 patients with biliary disease. Indications for sphincterotomy were: 48 patients with choledocholithiasis, 3 patients with malignant biliary obstruction, and 2 patients with papillary stenosis. The procedure was successful in 52 patients (98.1%). In patients with choledocholithiasis, the stones were successfully removed or passed out spontaneously in 42 patients (87.5%). Endoscopic retrograde biliary drainage (ERBD) was successfully carried out in 2 cases of malignant biliary obstruction after EST. The clinical and biochemical evidence of cholestasis resolved in both patients with papillary stenosis. Complications consisted of hemorrhage (2 patients) and cholangitis (1 patient), resulting in one death. The overall complication and mortality rates were 5.7% and 1.9% respectively. Thirty-two patients received regular ultrasound examination follow-up with a mean of 13.4 months. Two patients had recurrent common bile duct stones and one had restenosis of papilla. The conditions were managed by endoscopic therapy. Endoscopic sphincterotomy is a relatively safe and effective means of relieving extrahepatic cholestasis; however, its comparison with surgical techniques needs long-term, randomized studies.
The purpose of this study was to identify preoperative and intraoperative variables predictive of left ventricular dysfunction 6 months after aortic valve replacement. Patients were considered to have postoperative left ventricular dysfunction if the end-diastolic-volume index was greater than or equal to 101 ml/m2 or if the ejection fraction was less than or equal to 0.50. Data from 180 patients entered into the Veterans Administration Cooperative Study on Valvular Heart Disease who had technically satisfactory cardiac catheterizations 6 months postoperatively were analyzed by a series of univariate and multivariate analyses. For the 88 patients with preoperative aortic stenosis, the most powerful predictor of postoperative left ventricular dysfunction in the final multivariate model was preoperative left ventricular ejection fraction (p = 0.0001), followed by preoperative myocardial infarction (p = 0.012), aortic valve gradient (p = 0.020), and incomplete coronary revascularization (p = 0.059). Abnormal preoperative left ventricular ejection fraction had a sensitivity of 72% and a specificity of 82% in identifying patients with postoperative left ventricular dysfunction. Preoperative left ventricular systolic-volume index greater than or equal to 40 ml/m2 had a similar sensitivity and specificity (79% and 84%, respectively). For the 36 patients with aortic regurgitation, preoperative left ventricular ejection fraction was again the most powerful predictor of postoperative left ventricular dysfunction (p = 0.013), followed by left ventricular systolic pressure (p = 0.038) and arteriovenous oxygen difference (p = 0.054). For the 56 patients with mixed aortic stenosis and regurgitation, left ventricular systolic pressure (p = 0.007) and preoperative myocardial infarction (p = 0.022) were the variables predictive of postoperative left ventricular dysfunction. Although many patients with preoperative left ventricular dysfunction experience improved left ventricular performance after aortic valve replacement, performance does not always return to normal. For patients with either aortic stenosis or regurgitation, the strongest predictor of postoperative left ventricular dysfunction is preoperative dysfunction. These data support the concept that patients with moderate or severe aortic stenosis or regurgitation should be operated on before the onset of significant left ventricular dysfunction.