Biomedical subjects
Publications and source records attributed to G M Lemole.
Traumatic aortic valve rupture is a rare complication of nonpenetrating cardiac injury and can be caused by a tear or avulsion of the valve. The most common method of treatment has been valve replacement, although valve repair has been successful in a few cases of cusp tear or detachment. We report a case of aortic valve commissural avulsion in which a reparative technique was applied and the natural valve was preserved.
To evaluate the effect of laser-assisted fibrinogen bonding on the tensile strength of suture material, 10 types of sutures were exposed to various time intervals of diode laser energy after pretreatment with dye-enhanced fibrinogen solder. After exposure, each suture material was stressed on a tensometer and compared with nonlased suture material. Our results indicate that polytetrafluoroethylene suture material was virtually unaffected at all time intervals of exposure to laser energy. Polyester suture material retained 64.3% of its tensile strength at 60 sec of exposure to laser energy. White silk suture material maintained 80% of its initial tensile strength at 60 sec of exposure. These suture materials may be used safely in conjunction with laser-assisted fibrinogen bonding even if prolonged laser exposure is necessary. The other suture materials tested may be compromised significantly by prolonged exposure to laser energy and must be used with relatively shorter irradiation periods.
The effect of laser-assisted fibrinogen bonding (LAFB) on the development of intimal hyperplasia was studied with stress-strain profiles and histologic evaluation of canine arteriovenous fistulas (AVFs). In 19 animals femoral AVFs were created with an 808 nm diode laser after topical application of fibrinogen mixed with indocyanine green dye; in the contralateral limb a sutured AVF was created. The animals were divided into three groups. Group 1 dogs (n = 6) were killed serially up to 4 weeks after surgery to examine the healing of the anastomoses created with LAFB. Group 2 dogs (n = 6) were killed 1 month after surgery, and the fresh specimens were strained axially to produce a stress-strain profile graph. Group 3 dogs (n = 7) were killed 7 months after surgery, and the AVFs were infused with formalin under pressure and histologically prepared to allow comparison of the ratio of maximum to minimum intimal hypertrophy. Fibrinogen used for LAFB was resorbed during the first month after operation without evidence of foreign body reaction or inflammation. Tensile break force was not significantly different in the laser-bonded group (4.6 +/- 2.4 pounds) and the sutured group (4.3 +/- 1.7 pounds). The modulus (tensile break force per square inch), a measure of elasticity, identified the laser-bonded AVF (149 +/- 44 pounds per square inch) to be less rigid than the sutured AVF (203 +/- 35 pounds per square inch) (p less than 0.05). No significant differences in the degree of intimal hyperplasia were noted in any area of the anastomoses. Use of LAFB neither accelerates nor prevents intimal hyperplasia in a canine AVF model.(ABSTRACT TRUNCATED AT 250 WORDS)
Aortic insufficiency (AI) due to fibrosis and thickening of the nodules of Arantius in the otherwise normal aortic valve was found in 11 adults (age range, 41 to 65 years) between 1976 and 1988. Nine had concomitant mitral stenosis; 2 had coronary artery disease. In 6 patients AI was graded 3+ or greater; in 5 it was less than 3+. Correction of AI and restoration of cuspid flexibility and apposition by shaving the hypertrophied nodules was accomplished in all, with postrepair AI graded as 1+ or less. There was one hospital death, a patient who had prior mitral operation. Mean follow-up was 68 +/- 56 months. Only 1 patient had late (6 years) recurrent serious (3+) AI. Nine continued to have 1+ or less AI, based on echocardiography or catheterization (n = 6) or on physical examination performed at a mean of 74 months. We conclude that thickening of the nodules of Arantius may cause AI. Long-term correction can be accomplished by sculpturing of the involved cusps.
To determine the comparative efficacy of several histamine (H2)-receptor antagonists (cimetidine, famotidine, and ranitidine) and the antacid Mylanta-II (Stuart Pharmaceuticals, Wilmington, DE) in gastric pH control and the prevention of postoperative stress ulceration, a prospective, randomized study was performed in a homogeneous population of patients with elective coronary artery bypass. None of the 57 patients in the study population had a documented history of ulcer disease. There were four treatment groups, each with similar demographics (age and sex). Cimetidine-treated group consisted of 15, famotidine-treated group of 18, ranitidine-treated group of 19, and antacid-treated group of 5 patients. There was no hemodynamically significant postoperative gastrointestinal bleeding in any of the patients. When the agents were compared for efficacy of gastric pH control, statistically better pH control was found in the famotidine- and ranitidine-treated groups (P less than 0.003) than in the cimetidine-treated group (pH less than or equal to 4.0) during the 20-hour observation period. Side effects (hematologic and neurological) were noted only in the cimetidine-treated group. The results of this study indicate that in patients in postoperative intensive care, better gastric pH control, and thus prevention of gastric stress ulcers, is achieved with either famotidine or ranitidine rather than cimetidine or antacid.
Characterization of the stress-strain profiles of welded tissue would provide an additional means of analyzing this new technology and comparing it with alternative anastomosing techniques. Rabbit longitudinal aortotomies were repaired with either 7-O polypropylene sutures or an 808-nm diode laser (power density, 4.8 watts/cm2) after topical application of fibrinogen mixed with indocyanine green dye (peak absorption, 805 nm). The rabbits were sacrificed between 0 and 28 days, and the fresh aortic specimens were strained axially in diluted plasma solution until ultimate breakage occurred in order to produce a stress-strain profile graph. No significant differences were noted between sutured and bonded aorta at any time interval. Nonincised aortic tissue (378 lb/in2) withstood significantly higher stress (P less than 0.05) than both sutured (257 lb/in2) and bonded (210 lb/in2) groups at the time of creation. By 7 days after operation, however, no significant differences were noted among any of the three groups. At 28 days after operation, the laser-bonded aorta was significantly stronger than the control aorta (P less than 0.05). The only significant difference in modulus (stretchability) identified the sutured aorta (373 lb/in2) to be more rigid than the control aorta (231 lb/in2) (P less than 0.05). Both sutured and laser-bonded anastomoses are weaker than control aorta initially; however, after an early critical period, both treatments achieve the strength of control aorta. By 1 month postoperatively, sutured anastomoses have the disadvantage of being less distensible.
OBJECTIVE: To determine the efficacy of a lanolin-based gel in preventing radioactive particle and viral penetration. DESIGN: Paired, stacked filter discs were held in a stainless steel support, and the gel was applied manually to the upper surface of the upper filter. Indicator solution containing either radioactive viral particles (3H-labeled simian virus 40 or 3H-labeled woodchuck hepatitis virus) or 20 microliters or 100 microliters of 32P-labeled radioactive compounds of much lower molecular weight then were applied to the upper filter. The filter discs were separated after 30 minutes, and the lower disc was examined for radioactivity in a liquid scintillation counter. RESULTS: Transmission of radioactive particles was statistically significantly reduced by the application of the ointment on the upper filter (from 6.7 +/- 0.1 x 10(5) counts per minute [cpm] to 88 +/- 38 cpm). Transmission of both labeled viral particles also was reduced to a similar degree. CONCLUSIONS: Application of protective ointment to the filters significantly reduces transmission of radioactive viral particles and smaller radioactive compounds through filter discs. Use of this ointment may offer similar mechanical protection against the transmission of viruses between patient and healthcare provider.
A 38-year-old woman with complete occlusion of the left main coronary artery secondary to cannulation during aortic valve replacement is presented. The clinical course was characterized by progressive left ventricular dysfunction and congestive heart failure. Recognition of this potential problem when it occurs is important as to institute therapeutic measures which may interrupt a patient's progressive clinical deterioration.
Complications after aortic replacement that result from prolonged graft insertion time and technical difficulties with suturing through friable, diseased aortic tissue can be addressed with use of the sutureless intraluminal ring graft. Between 1978 and 1989, we replaced the ascending aorta or aortic arch with this device in 49 patients. At no time were we unable to use a sutureless graft during a procedure. Twenty-eight cases of aneurysmal disease and 21 cases of acute or chronic dissection were treated. Twenty-six patients required replacement of the aortic valve, with annuloartic ectasia being the most common indication (71%). Ten patients underwent concomitant coronary artery bypass grafting. The operative mortality rate for ascending aortic aneurysm repairs was 4%, and that for dissections was 18%. Five of 8 patients requiring aortic arch replacement survived. Most patients were studied angiographically before discharge. No complications were related to anastomotic hemorrhage, pseudoaneurysm formation, graft migration, or thromboemboli. Individual cases of phrenic nerve palsy, acute tubular necrosis, and transient ischemic attack, all of which resolved completely, were identified. The actuarial 5-year survival rate is 64%. We conclude that modification of the sutureless intraluminal ring graft to suit the pathology encountered at operation allows the quickest repair with the least chance of anastomotic complication.
The stenotic aortic valve was surgically repaired in 48 adults, 21 women and 27 men, aged 38 to 83 years. Five had congenital aortic stenosis (AS), with a mean aortic valve gradient and area of 58 +/- 23 mm Hg (standard deviation) and 0.54 +/- 0.13 cm2, respectively; 32 had senile AS with a mean aortic valve gradient and area of 43 +/- 20 mm Hg and 0.98 +/- 0.41 cm2; and 11 had rheumatic AS with a mean aortic valve gradient and area of 59 +/- 24 mm Hg and 0.47 +/- 0.15 cm2. Only 6 patients underwent isolated aortic valvoplasty, 11 underwent concomitant mitral valve procedure, and 34 underwent concomitant coronary revascularization. Repair consisted of decalcification in 33 patients and decalcification as well as commissurotomy in 15 patients. There were three hospital deaths, none related to the aortic valve. Only 2 patients (both rheumatic) did not improve clinically. During follow-up (mean, 64 +/- 41 months) aortic valve restenosis developed in 24% (10 patients, 3/5 congenital, 4/11 rheumatic, and 3/32 senile) at a mean of 64 +/- 28 months. Postoperative Doppler echocardiographic assessment of 21 patients with senile AS at 1.1 +/- 2.7 and 18.1 +/- 1.4 months showed significantly lower aortic valve gradient and improved area in comparison with preoperative values. At 36 +/- 2.7 months, aortic valve gradient and area were not significantly different than preoperative values, and at 58.5 +/- 2.6 months aortic valve gradient was 1.41 (p = 0.07) times the preoperative value. At 7 years, actuarial freedom from aortic valve-related symptoms of the patients with senile AS was 87%. We conclude that in select patients aortic valve repair results in excellent relief of AS. Late restenosis is expected and more likely to occur in the valves with congenital and rheumatic disease than in those with senile disease.
Pulmonary function testing was conducted consecutively in 29 healthy men (age range, 42 to 71 years) undergoing elective coronary artery bypass grafting. Lung volumes, expiratory flow rates, diffusing capacity, and blood gases were determined before operation, at discharge (8.7 +/- 1.9 days), and at 3 months postoperatively. In addition, peak expiratory flow rate was measured immediately after extubation (21.4 +/- 2.7 hours). Fifteen patients had smoked within the past year, but none had a history of pulmonary impairment. Twenty-two patients had internal mammary artery (IMA) dissection. Operation and recovery were uneventful in all cases. After extubation, peak expiratory flow rate was decreased by 65%. At discharge, lung volumes were decreased by 19% to 33% below preoperative values and expiratory flow rates were decreased by 33% to 37% below preoperative values. Some minor changes were detected at 3 months. Further analysis of these changes according to smoking history, age, preoperative weight, dissection of IMA, and aortic cross-clamp time showed that only IMA dissection affected the postextubation changes in peak expiratory flow rate (p less than 0.0001), whereas the decreases in functional residual capacity and expiratory reserve volume at discharge were affected by IMA dissection (p less than 0.05) and age (p = 0.01). Thus, median sternotomy is associated with severe but short-term pulmonary dysfunction; IMA dissection has a significant adverse effect on these changes.
The thulium-holmium-chromium:yttrium-aluminum-garnet (THC:YAG) laser has a tissue effect similar to that of the CO2 laser, with the advantage of transmissibility through flexible fibers. The authors used a human-rabbit xenograft model to evaluate the thrombotic and healing responses of atherosclerotic vessels subjected to laser energy. Occluded atherosclerotic human coronary artery segments were recanalized in vitro by use of the THC:YAG laser. Destruction of plaque by the laser was achieved with minimal collateral thermal damage. These vascular segments were then transplanted into the rabbit abdominal aorta. The authors observed that the luminal surface of the lased vessels was more thrombogenic than that of the nonlased control vessels. However, occlusion of the lased vessels did not occur. Repair of laser-treated tissue progressed until a mature, nonthrombogenic fibrin-platelet aggregate was adherent to the luminal wall. Overall, the lased vessels behaved in a fashion similar to the nonlased control vessels. On the basis of these results, the authors believe that the THC:YAG laser may have use in human angioplasty.
From 1980 to 1988, 30 patients from a total population of 123 recipients of sutureless grafts (24%) have required aortic reconstruction with a composite ringed graft. Replacement of the ascending aorta was required in 12 patients, of the aortic arch in six patients, of the descending aorta in two patients, of the thoracoabdominal aorta in two patients, and of the abdominal aorta in eight patients. Eight patients (27%) needed an emergency operation at the time of admission. No patients had permanent neurologic or renal deficits. There was no evidence of pseudoaneurysm formation, graft erosion, graft migration, or aortic bleeding in the postoperative period. Two operative deaths (7%) occurred, both in patients undergoing arch reconstruction. Composite grafts can be created that vary in length and shape, incorporate different graft materials, and accommodate the aorta and its branches. The ability to modify the sutureless prosthesis to suit the disease encountered at operation allows the quickest repair with the least chance of anastomotic complication.
A new sutureless intraluminal graft has been developed with a ring made of a coiled, overlapping, stainless steel spring with ratchets in one overlapping end. This graft is flexible during insertion but becomes rigid after proper intraaortic placement as the spool is dilated and the ratchest lock into position. The new graft was implanted in 10 dogs and was evaluated histologically and angiographically at various intervals. No ring dislodgment, aortic rupture, stenosis, or aneurysmal dilation was observed. The flexible component of this graft allows it to be introduced and secured in place easily and provides a technical advantage compared with the clinically used rigid intraluminal graft.
A case is reported in which the use of heterologous bovine pericardium in coronary revascularization was associated with firm adhesions and complete occlusion of all vein grafts after eight months. Heterologous pericardial substitutes may have a deleterious effect on vein grafts and may not avert epicardial-pericardial adhesions.
Use of the intraluminal sutureless ringed prosthesis can reduce graft insertion time and avoid difficulties inherent in suturing to friable, diseased aortic tissue. Since 1976 this device has been inserted into the descending thoracic or thoracoabdominal aorta in 42 procedures for aortic dissection and for aneurysmal disease. The operative mortality rate for descending thoracic aortic dissection repair was 14% and that for descending thoracic aortic aneurysm repair was 8%, with an overall mortality rate of 10%. All three of the patients undergoing thoracoabdominal aortic replacement survived. The mean cross-clamp time for sutureless tube graft insertion was 9 minutes. The average blood replacement was 2.4 units/patient. No patient suffered serious neurologic or renal impairment. A single nonfatal case of graft dislodgement occurred after placement. No evidence of hemolysis, pseudoaneurysm formation, graft erosion, graft migration, or anastomotic bleeding was present in any of the remaining patients. Modification of the sutureless intraluminal device to suit the pathologic condition encountered at operation allows rapid repair with a low incidence of anastomotic complication.
To evaluate our experience with sutureless intraluminal ringed grafts in the abdominal aorta, we reviewed all patients who were managed with this device from 1980 to 1987. Thirty-one patients were identified with a mean follow-up time of 41 months. Three patients had suprarenal aneurysms and four had ruptured abdominal aneurysms. Average tube graft insertion time was 17 minutes and required 0.9 units of transfused blood. There were two postoperative deaths (6 percent), both secondary to myocardial infarction. None of the patients with ruptured or suprarenal aneurysms died. No patients had permanent renal or neurologic deficits, and no instances of postoperative bleeding, wound infection, pseudoaneurysm formation, or graft migration were encountered. The sutureless intraluminal graft can be implanted easily and quickly and is safe for use in the abdominal aorta. It is particularly helpful in the management of suprarenal or ruptured abdominal aneurysms, in which speed is important, and in effecting technically difficult anastomoses to friable aortic tissue.
Renal failure and paraplegia are major complications of operations on the descending thoracic aorta. To minimize cross-clamp time and reduce the incidence of such complications, we have used an intraluminal ring graft to reestablish aortic continuity in patients with descending thoracic aortic lesions. From March 1978 to December 1986, we used this technique alone in 28 patients. There were 4 patients with traumatic aortic disruptions, 4 with dissections, 4 with expanding aneurysms, 2 with ruptured aneurysms, 1 with Marfan's syndrome, and 13 with atherosclerotic aneurysms that were repaired electively. The cross-clamp times ranged from 4 to 28 minutes. There were three early postoperative deaths (within 30 days) and one late postoperative death in the follow-up period (mean, 28.2 months). Ring dislodgement occurred only once, in the first patient in this series. There were no instances of postoperative renal failure or paraplegia. We conclude that the use of an intraluminal ring graft greatly reduces the aortic cross-clamp time and is a safe and effective technique.