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Biomedical subjects

H Laks

Publications and source records attributed to H Laks.

At least 181 records · Page 10Linked to original sources

Preoperative duplex scan assessment of the inferior epigastric artery as a coronary bypass conduit.

The inferior epigastric arteries are currently being evaluated as alternative autologous arterial conduits for coronary artery bypass operations. The inferior epigastric arteries are variable in diameter and length and require harvesting through separate abdominal incisions. There is a need, therefore, for a method to preoperatively assess the diameter and length of the inferior epigastric arteries to determine their suitability as a coronary artery bypass graft. We have found that the duplex scan is a valuable noninvasive preoperative imaging modality to evaluate the inferior epigastric arteries.

Abdominal Muscles↗

Repair of truncus arteriosus in infancy.

Improvements in myocardial protection, surgical technique, and postoperative care have decreased operative mortality for neonatal repair of truncus arteriosus. Primary repair of truncus arteriosus in infancy without prior pulmonary artery banding is currently the preferred approach. During the period from 1982 to December 1990, 32 patients under the age of 12 months underwent surgical correction of truncus arteriosus at UCLA. The average age was 3.5 months (range, 12 days to 12 months). Three patients had interrupted aortic arch. Early mortality for the entire group was 15.6% (5/32); for those older than 1 month early mortality was 7% (2/28). In the past 4 years, early mortality has decreased to 8.3% (2/24); both of these patients had interrupted aortic arch. Excluding patients with interrupted aortic arch, there were no early deaths in the last 22 patients (1986 to 1990). Late mortality overall was 7.4% (2/27). In a mean follow-up of 73 months (range, 40 to 110 months), 71% (5/7) of the survivors with Dacron porcine-valved conduits required conduit replacement secondary to obstruction. In a mean follow-up of 36 months (range, 1 to 89 months), only 14% (3/21) of the patients with homografts required replacement secondary to obstruction.

Age Factors↗

Dacron mesh wrapping to support the aneurysmally dilated or friable ascending aorta.

A technique of supporting the aneurysmally dilated or friable ascending aorta using a fine Dacron mesh is described. In patients with aneurysmal dilatation of the ascending aorta, longitudinal resection of a portion of the aneurysm combined with wrapping can avoid replacement with a synthetic graft. The Dacron mesh, because of its transparency and ability to stretch, allows a more accurate fit over the aorta, avoids hematoma formation, provides visualization of suture lines after wrapping, and facilitates proximal vein graft anastomoses for combined aortocoronary bypass.

Aged↗

Partial Fontan: advantages of an adjustable interatrial communication.

Systemic venous hypertension after the Fontan procedure is a major cause of mortality and morbidity, accounting for 11 of 16 deaths in our series of 228 Fontan procedures. A partial Fontan with a residual atrial septal defect (ASD) would allow controlled right-to-left shunting to reduce venous pressure and improve cardiac output while maintaining a reduced but acceptable arterial oxygen saturation. This allows complete or graded closure of the ASD after the discontinuation of cardiopulmonary bypass in the operating room or at any time in the postoperative period by exposing the snare under local anesthesia. From 1987 to 1990, 36 patients undergoing the modified Fontan procedure had placement of an adjustable interatrial communication. Indications for placement of an adjustable ASD included increased pulmonary artery pressures, increased pulmonary vascular resistance, reactive airway disease, previously increased or unknown pulmonary vascular resistance, small pulmonary arteries, and borderline ventricular function. Fourteen patients had the adjustable ASD closed at the time of operation, 8 patients underwent narrowing, and 12 underwent closure of the ASD in the postoperative period. Eight patients were discharged with the ASD partially open, and 2 patients underwent delayed closure. The partial Fontan with an adjustable ASD may increase the safety of the Fontan procedure for high-risk groups such as those with increased pulmonary vascular resistance, pulmonary hypertension, and impaired left ventricular function and for infants, who tolerate venous hypertension poorly. The ability to adjust the ASD in stages depending on the hemodynamic response increases flexibility and safety.

Animals↗

Total cavopulmonary anastomosis versus conventional modified Fontan procedure.

The total cavopulmonary anastomosis, lateral tunnel Fontan, has been advocated as a preferred method for Fontan type repair. From 1987 to July 1990, 39 patients underwent total cavopulmonary anastomoses (group 1) and 39 patients underwent modified Fontan procedures (group 2); patients receiving adjustable atrial septal defects were excluded. Diagnoses in group 1 included tricuspid atresia in 5 patients, single ventricle in 32, and pulmonary atresia and intact ventricular septum in 2. Diagnoses in group 2 included tricuspid atresia in 20, single ventricle in 17, hypoplastic left heart syndrome in 1, and pulmonary atresia and intact ventricular septum in 1. There were no significant differences in age, weight, cross-clamp time, duration of inotropic support, postoperative effusions, or hospital stay between the two groups. Early mortality in group 1 was 7.7% (3/39) and in group 2, 2.6% (1/39). There was no difference in the incidence of early dysrhythmias or early pacemaker placement. Late mortality was 2.8% in group 1 and 8% in group 2 with a mean follow-up of 18 and 25 months, respectively. Follow-up in group 1 revealed 33 patients in normal sinus rhythm and 1 patient with episodes of supraventricular tachycardia; no additional patients have required pacemakers. Follow-up in group 2 revealed 27 patients in normal sinus rhythm and supraventricular tachycardia in 4 patients; 5 additional patients have required pacemaker placement. There is no apparent difference in early outcome between the total cavopulmonary anastomosis and the conventional modified Fontan. However, there appears to be an increased incidence of late dysrhythmias and the need for pacemaker placement in the conventional modified Fontan group compared with the lateral tunnel group.

Adolescent↗

Decreasing survival benefit from cardiac transplantation for outpatients as the waiting list lengthens.

Many patients are accepted for cardiac transplantation during a period of clinical instability associated with a high risk of death, even though most can be discharged home to await transplantation. As the waiting lists lengthen, priority is awarded solely on the basis of the waiting time of outpatients, who now usually undergo transplantation after they have already survived a major period of jeopardy. To determine the impact of the current waiting times and priority system on the previously expected benefit offered by transplantation, 1-year actuarial survival without transplantation was recalculated after each month without transplantation for 214 potential candidates with an ejection fraction of 0.17 +/- 0.05 discharged on tailored medical therapy after evaluation. These data were compared with the 1-year survival data of 88 outpatients who underwent transplantation. Actuarial survival after 1 year was 67% on tailored therapy compared with 88% after transplantation (p = 0.009). Death without transplantation was sudden in 43 of 51 patients, resulting from hemodynamic decompensation in 8. For outpatients already surviving 6 months without transplantation, actuarial survival over the next 12 months was 83% without transplantation. Thus, the expected improvement in survival after transplantation would be only 5% over the subsequent year for patients waiting 6 months, which is the waiting time for many outpatients. Such patients should be reevaluated to determine whether transplantation remains indicated during the next year.

Actuarial Analysis↗

A technique to harvest the inferior epigastric arteries for coronary bypass procedures.

The demonstrated superior long-term patency of the internal mammary artery (IMA) over the saphenous vein (SV) has prompted the use of other arterial grafts, particularly for younger patients and patients without a suitable SV. We have used the single or bilateral inferior epigastric arteries (IEA) as a detached arterial conduit in 27 patients undergoing coronary artery bypass operations (CABG). In this report we describe the surgical anatomy of the IEA, preoperative noninvasive evaluation by duplex scan, our harvesting technique, and early surgical experience.

Abdominal Muscles↗

Interaction of monocytes with cocultures of human aortic wall cells involves interleukins 1 and 6 with marked increases in connexin43 message.

Medium from cocultures of human aortic endothelial cells (HAEC) and smooth muscle cells (HASMC) taken from the same donor contained approximately two- to fourfold more macrophage colony-stimulating factor, granulocyte/macrophage colony-stimulating factor, and up to 5.1-fold more transforming growth factor beta than could be accounted for by the sum of the activities of media from equivalent numbers of HAEC and HASMC cultured separately. After pulse labeling, immunoprecipitated [35S]fibronectin and [14C]collagen were also found to be substantially increased in the coculture compared to the sum of HAEC and HASMC cultured separately. The cocultivation of HAEC and HASMC resulted in a 2.7-fold increase in connexin43 messenger RNA. When direct physical contact between HAEC and HASMC was prevented by a membrane that was permeable to medium, the levels of [35S]fibronectin and [14C]collagen in the coculture were significantly reduced. Monocytes cultured alone contained low levels of [35S]fibronectin and [14C]collagen but when added to the coculture there was up to a 22-fold increase in [35S]fibronectin and a 1.9-fold increase in [14C]collagen compared to the coculture alone. The increase in fibronectin was prevented in the presence of neutralizing antibody to interleukin 1 and antibody to interleukin 6 by 45% and 67%, respectively. Addition of monocytes to cocultures also induced the levels of mRNA for connexin43 by 2.8-fold. We conclude that the interaction of HAEC, HASMC, and monocytes in coculture can result in marked increases in the levels of several biologically important molecules and that increased gap junction formation between the cells and interleukins 1 and 6 may be partially responsible for these changes.

Aorta↗

Monocyte transmigration induced by modification of low density lipoprotein in cocultures of human aortic wall cells is due to induction of monocyte chemotactic protein 1 synthesis and is abolished by high density lipoprotein.

Incubation of cocultures of human aortic endothelial (HAEC) and smooth muscle cells (HASMC) with LDL in the presence of 5-10% human serum resulted in a 7.2-fold induction of mRNA for monocyte chemotactic protein 1 (MCP-1), a 2.5-fold increase in the levels of MCP-1 protein in the coculture supernatants, and a 7.1-fold increase in the transmigration of monocytes into the subendothelial space of the cocultures. Monocyte migration was inhibited by 91% by antibody to MCP-1. Media collected from the cocultures that had been incubated with LDL induced target endothelial cells (EC) to bind monocyte but not neutrophil-like cells. Media collected from cocultures that had been incubated with LDL-induced monocyte migration into the subendothelial space of other cocultures that had not been exposed to LDL. In contrast, media from separate cultures of EC or smooth muscle cells (SMC) containing equal number of EC or SMC compared to coculture and incubated with the same LDL did not induce monocyte migration when incubated with the target cocultures. High density lipoprotein HDL, when presented to cocultures together with LDL, reduced the increased monocyte transmigration by 91%. Virtually all of the HDL-mediated inhibition was accounted for by the HDL2 subfraction. HDL3 was essentially without effect. Apolipoprotein AI was also ineffective in preventing monocyte transmigration while phosphatidylcholine liposomes were as effective as HDL2 suggesting that lipid components of HDL2 may have been responsible for its action. Preincubating LDL with beta-carotene or with alpha-tocopherol did not reduce monocyte migration. However, pretreatment of LDL with probucol or pretreatment of the cocultures with probucol, beta-carotene, or alpha-tocopherol before the addition of LDL prevented the LDL-induced monocyte transmigration. Addition of HDL or probucol to LDL after the exposure to cocultures did not prevent the modified LDL from inducing monocyte transmigration in fresh cocultures. We conclude that cocultures of human aortic cells can modify LDL even in the presence of serum, resulting in the induction of MCP-1, and that HDL and antioxidants prevent the LDL induced monocyte transmigration.

Antioxidants↗

Complete functional recovery after 24-hour heart preservation with University of Wisconsin solution and modified reperfusion.

Successful long-term myocardial preservation is dependent on optimizing conditions during arrest, storage, and reperfusion. Neonatal piglet hearts were arrested and stored in University of Wisconsin solution (UW) at 4 degrees C for 24 hours and reperfused on a blood-perfused, adult animal-supported isolated circuit. Results were compared with nonischemic continuously perfused control hearts (group 1, n = 5). The initial 10 minutes of reperfusion in groups 2-4 was modified by aspartate/glutamate-enriched leukocyte-depleted blood cardioplegia (group 2, n = 7), leukocyte depletion alone (group 3, n = 9), and aspartate/glutamate-enriched blood cardioplegia alone (group 4, n = 6). After 10 minutes, perfusion was continued with unmodified whole blood. In group 5 (n = 9), unmodified whole blood was used for initial reperfusion as well as subsequent perfusion. The stroke work index was determined 60 minutes after reperfusion. Biopsies for high-energy phosphates, myocardial water content, and electron microscopy were obtained after functional assessment. The stroke work index at left ventricular end-diastolic pressure of 9 mm Hg did not differ between groups 1 and 2 (19.0 +/- 1.4 x 10(3) and 19.0 +/- 1.5 x 10(3) [mean +/- SEM] erg/g, respectively). These were both different from group 5 (13.3 +/- 0.8 x 10(3) erg/g, p less than 0.05). Group 3 showed improved function (15.7 +/- 0.7 x 10(3) erg/g), but this did not reach statistical significance when compared with group 5. No difference was found between groups 4 and 5. Myocardial water content, high-energy phosphate levels, and ultrastructure were similar in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

Results of total cavopulmonary connection in the treatment of patients with a functional single ventricle.

Total cavopulmonary connection was proposed as a modification of the Fontan procedure that might have greater benefits than previous methods. To assess this procedure we reviewed case histories of 38 patients (aged 17 months to 30 years) who underwent Fontan procedures with cavopulmonary anastomoses between January 1987 and December 1989. The group included 32 patients with univentricular heart, 2 with pulmonary atresia and intact ventricular septum, 3 with tricuspid atresia, and 1 with hypoplastic left heart syndrome. One or more previous palliative procedures were performed in 34 patients, including 19 systemic-pulmonary shunts, 16 pulmonary artery bandings, 7 atrial septectomies/septostomies, 7 Glenn shunts, and 1 patent ductus arteriosus ligation. Preoperative hemodynamics showed a pulmonary artery pressure of 12 mm Hg (range 6 to 22 mm Hg), pulmonary-systemic flow ratio of 1.6 (range 0.37 to 3.0), left ventricular end-diastolic pressure 9 mm Hg (range 3 to 15 mm Hg), and systemic arterial oxygen saturation of 82% (range 67% to 94%). Concomitant with cavopulmonary connection, 13 patients underwent additional procedures, including 9 atrioventricular valve annuloplasties, 4 Damus-Stansel-Kaye procedures, and 2 resections of subaortic membranes. Modifying the Fontan procedure in this fashion was particularly useful in the management of 2 patients with pulmonary atresia and intact ventricular septum who had right ventricular-dependent coronary blood flow. Cavopulmonary anastomosis and atrial septectomy were performed in both patients, with resultant inflow of oxygenated blood to the right ventricle and coronary arteries. Excellent postoperative results were noted in each. Postextubation hemodynamics for the entire group included a mean right atrial pressure of 13 mm Hg (range 11 to 17 mm Hg), a mean left atrial pressure of 6 mm Hg (range 3 to 12 mm Hg), and a room air oxygen saturation of 96% (range 92% to 98%). Seven patients had pleural effusions, 3 required postoperative pacemaker placement, and 2 required reoperation for tamponade. A venous assist device was required in one patient on the second postoperative day, but the patient was weaned successfully within 24 hours. One early death (2.6%) occurred in a patient who had intractable ventricular fibrillation 2 days after operation. There was one late cardiac death (2.7%) caused by ventricular failure and one late noncardiac death. These results demonstrate that total cavopulmonary connection provides excellent early definitive treatment, with low morbidity and mortality, for a variety of complex congenital heart lesions.

Adolescent↗

Ischemic cardiomyopathy. Criteria for coronary revascularization and cardiac transplantation.

Because of the shortage of donor hearts, 16 (33%) of 48 patients with ischemic cardiomyopathy died awaiting transplantation. Determining factors that predict effective coronary revascularization and identifying patients who may benefit from revascularization is crucial. From 1984 to 1990, 207 ischemic cardiomyopathy patients were evaluated for heart transplantation; 131 were accepted (83 transplanted), 54 were not accepted, and 22 were revascularized (19 underwent bypass graft surgery and three underwent percutaneous transluminal coronary angioplasty). Four bypass patients failed early (less than or equal to 30 days, three deaths and one urgent heart transplant) and two late deaths (greater than or equal to 1 year) occurred. Overall mortality was 27%. Three-year survival of revascularized and transplanted patients was 72 +/- 10% and 73 +/- 6%, respectively. Successfully revascularized patients had preoperative ejection fraction, left ventricular end-diastolic dimension, and New York Heart Association functional class of 26 +/- 9%, 68 +/- 3 mm, and 3.9 +/- 0.4, respectively, compared with 36 +/- 9% (p less than 0.05), 64 +/- 6 mm (p = NS), and 1.2 +/- 0.4 (p less than 0.05) after revascularization. Preoperative ejection fraction of patients failing revascularization was 15 +/- 4% (p = NS compared with successful revascularization), and left ventricular end-diastolic dimension was 81 +/- 4 mm (p less than 0.05). Preoperative positron emission tomography imaging myocardial blood flow and glucose metabolism was performed in 12 patients: 10 patients with scans predicting reversible ischemia were successfully revascularized, and two patients with negative scans had failed revascularization.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗

Cardiac preservation in patients undergoing transplantation. A clinical trial comparing University of Wisconsin solution and Stanford solution.

Recent laboratory investigations have shown significantly improved donor heart preservation and function when the University of Wisconsin solution (UW) is used for arrest and storage. These findings prompted us to compare UW to Stanford solution in a clinical trial. After giving informed consent, patients were blindly randomized to receive a heart arrested and stored in UW or a heart arrested in Stanford solution and stored in normal saline. Orthotopic transplants were performed in a routine manner. Fourteen patients with a mean age of 54 years were randomized to UW, and 15 patients with a mean age of 51 years were randomized to Stanford solution. Mean donor ages (UW 27 years, Stanford 24 years) and ischemic times (UW 150 minutes, Stanford 135 minutes) were similar. Several differences were observed intraoperatively. At end ischemia, mean adenosine triphosphate (UW 5.87 mmol/gm wet weight, Stanford 4.75 mmol/gm) and creatine phosphate (UW 9.26 mmol/gm, Stanford 4.75 mmol/gm) levels were higher in the UW hearts (p less than 0.05). Defibrillation requirements (UW 14% [2/14], Stanford 53% [8/15]) were significantly less in the UW group (p = 0.05). The number of patients requiring temporary intraoperative pacing also showed a significant difference with 7% (1/14) of UW patients versus 47% (7/15) of Stanford patients requiring pacing (p less than 0.05). Intraoperative requirement for inotropic support showed a trend in favor of the UW group. End-ischemic and postreperfusion histologic characteristics were similar between the two groups. No differences in hemodynamics or ejection fractions were noted postoperatively, but trends toward improved rhythm and decreased inotropic support were present in the UW group. Overall 6-month survival rates were similar (UW 86% [12/14], Stanford 93% [14/15]). No preservation-related deaths occurred. We conclude: (1) UW is a safe and effective preservation solution for human cardiac transplantation; (2) considering the improved end-ischemic adenosine triphosphate and creatine phosphate levels, decreased defibrillations, decreased intraoperative pacing, and trend toward decreased requirement for inotropic support in the UW group, UW appears to be superior to Stanford solution for donor heart preservation.

Adenosine Triphosphate↗

Gastrointestinal complications after cardiac transplantation: a spectrum of diseases.

Cardiac transplantation has become an accepted treatment modality for end-stage cardiac failure. The gastrointestinal (GI) tract represents a potential source of posttransplant morbidity and mortality. To define the scope of this problem, records of all patients undergoing cardiac transplantation at UCLA between January 1984 and July 1989 were reviewed. In all, there were 120 patients (90 males and 30 females) with a mean age of 45.4 yr. Among them, there were 61 patients (51%) who developed a total of 112 posttransplant GI complications. Of the entire 120 patients, 41 (34%) developed minor complications and 20 (17%) sustained major GI morbidity. Eighteen patients (15%) underwent either endoscopy or surgical intervention. These data suggest that most cardiac transplant recipients will experience some form of GI complication, although most are minor and can be managed conservatively. However, when major, life-threatening complications occur, evaluation and intervention should proceed expeditiously. The gastroenterologist and GI surgeon should play complimentary roles in the care of these complicated patients.

Adolescent↗