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Biomedical subjects

H G Borst

Publications and source records attributed to H G Borst.

At least 55 records · Page 3Linked to original sources
PubMed1994

Low-dose cyclosporine therapy in triple-drug immunosuppression for heart transplant recipients.

The toxicity of long-term immunosuppressive therapy has become a major concern in long-term follow-up of heart transplant recipients. In this respect the quality of renal function is undoubtedly linked to cyclosporin A (CsA) drug levels. In cardiac transplantation, specific CsA trough levels have historically been maintained between 250 and 350 micrograms/L in many centers without direct evidence for the necessity of such high levels while using triple-drug immunosuppression. This retrospective analysis compares the incidence of acute and chronic graft rejection as well as overall mortality between groups of patients with high (250 to 350 micrograms/L) and low (150 to 250 micrograms/L) specific CsA trough levels. A total of 332 patients who underwent heart transplantation between October 1985 and October 1992 with a minimum follow-up of 30 days were included in this study (46 women and 276 men; aged, 44 +/- 12 years; mean follow-up, 1,122 +/- 777 days). Standard triple-drug immunosuppression included first-year specific CsA target trough levels of 250 to 300 micrograms/L. Patients were grouped according to their average creatinine level in the first postoperative year (group I, < 130 mumol/L, n = 234; group II, > or = 130 mumol/L, n = 98). The overall 5-year survival excluding the early 30-day mortality was 92% (group I, 216/232) and 91% (group II, 89/98) with 75% of the mortality due to chronic rejection. The rate of rejection for the entire follow-up period was similar in both groups (first year: group I, 3.2 +/- 2.6 rejection/patient/year; group II, 3.6 +/- 2.7 rejection/patient/year; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Improvement of tracheal autograft revascularization by means of fibroblast growth factor.

Ischemic airway complications after lung transplantation remain a significant problem despite the use of bronchial omentopexy. Clinical observations suggest that enhancement of vascular ingrowth could possibly increase the efficacy of a bronchial omental flap. This study was therefore designed to investigate whether basic fibroblast growth factor can enhance blood supply of an ischemic airway by acceleration of vascular ingrowth in a rabbit autotransplant model. Segments of the trachea were harvested and transplanted into a subcutaneous pouch. The animals were randomly assigned to one of four groups: group I, no omentopexy; group II, omentopexy; group III, omentopexy and fibrin glue; or group IV, omentopexy and fibrin glue enriched with 2.5 micrograms basic fibroblast growth factor. After 14 days the animals were sacrificed. The extent of perfusion was investigated by means of radioactive microspheres. The morphology of the tracheal segments was investigated in a blinded fashion macroscopically, by means of light microscopy, and by means of scanning electron microscopy. The radioactivity measurements revealed a significantly increased perfusion of group IV (77% +/- 42%) as compared with groups I (17% +/- 13%) and III (20% +/- 16%). By macroscopic and light microscopic assessment, the epithelial integrity of group IV was significantly improved compared with groups I and II. At electron microscopy the integrity of group IV was significantly superior to all remaining groups. We conclude that a deposit of basic fibroblast growth factor and fibrin glue appears to increase revascularization of an ischemic airway from omentum and thus results in improved epithelial preservation of a tracheal autograft.

Animals↗
PubMed1994

Surgical interventions in ischemic ventricular tachyarrhythmias--endocardial resection or implanted cardioverter/defibrillator.

The surgical therapy of ventricular tachyarrhythmias (VTA) in ischemic heart disease is attracting attention, since current medical therapies are showing limited long-term efficacy. The curative concept of electrophysiologically guided endocardial resection (ER) and palliation with the implantable cardioverter/defibrillator (ICD) are compared retrospectively. From 1980-1992, 121 patients (55 +/- 9 years, 108 males, 13 females) underwent ER and 203 patients (59 +/- 9 years, 195 males, 8 females) received an ICD for ischemic VTA. Concomitant coronary revascularization was performed in 38/121 patients with ER (31%) and in 62/203 patients (31%) with ICD. Perioperative mortality was 8% (10/121 patients) for ER and 5% (10/203 patients) for ICD (P = n.s.). Hundred eleven patients with ER (mean follow-up 41 +/- 37 months) and 193 with ICD (mean follow-up 22 +/- 20 months) were available for survival analysis: freedom from sudden death was comparable for the two groups at 1 year (99% for ICD, and 94% for ER) and at 5 years (90% for ICD and 90% for ER) (P = n.s.). Freedom from cardiac death also showed no differences between the groups at 1 year (94% for ICD, and 84% for ER) and at 5 years (74% for ICD and 74% for ER) (P = n.s.). Left ventricular function, indicated by left ventricular ejection fraction, was comparable (34 +/- 9% in ER, 30 +/- 11% with ICD) (P = n.s.) in the two groups. The linearized incidence of DC-shocks was 10.3/year in ICD patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Efficient tissue gluing in aortic dissection.

The authors' method for uniting the dissected aortic wall layers with the help of gelatine-resorcinol adhesive is described focusing on special instruments used in this conjunction.

Aortic Dissection↗
PubMed1994

Tactics and techniques of aortic arch replacement.

Operations on the nondissected and dissected aortic arch still pose challenges in terms of the need for and extent of aortic replacement. Our approaches to these lesions are described against the background of 204 operations (58 aneurysms, 54 chronic dissections, and 92 acute dissections), in terms of cerebral protection, procedural choices, and operative technique. Arch anastomoses sparing the supraaortic vessels had shorter periods of circulatory arrest (17.2 min) when compared to tubular arch replacement, with insertion of some or all of these vessels (33.7 min). Early death rates due to cerebral complications were lowest in acute dissections (3/14 fatalities, with two patients showing preoperative cerebral compromise). Based on our experience, we recommend doing subtotal or total arch replacement in aneurysms regardless of cause. Radical arch surgery should be avoided in acute dissections whenever feasible. Instead, the arch should be explored and a blood-tight distal anastomosis made, going beyond any entry tears encountered in that aortic portion.

Acute Disease↗
PubMed1994

Malperfusion of the thoracoabdominal vasculature in aortic dissection.

Ischemic damage to vital organs supplied by the thoracoabdominal aorta greatly increases the overall risk of aortic dissection. Of 320 patients operated upon for aortic dissection since 1985, 33 (10.3%) underwent operations directed at the relief of malperfusion (15/158 acute type A; 9/18 acute type B; 4/78 chronic type A; 5/66 chronic type B). Organs affected were the kidneys in 32; the bowel in 20; and the spinal cord in 1, while critical lower extremity ischemia was present in 11 patients. In total, 64 vascular areas were affected. Fenestration of the dissecting membrane with or without infrarenal grafting was the procedure performed most frequently in 25, followed by replacement of the descending or thoracoabdominal aorta in 6, and bypass grafting or direct revascularization of individual side branches in 6. Six other operations targeted at the affected organs were done. Twenty-four patients underwent one-stage operation for malperfusion; in 11, early reoperation after primary aortic repair was necessary, while 2 patients were operated electively. Ten of 33 patients died in hospital, 7 of malperfusion-induced complications. Of three late deaths, one was related to sequelae of malperfusion. We conclude that immediate diagnosis and prompt relief of malperfusion offer the best prospects for patient survival. Membrane fenestration appears to be the method of choice for treating malperfusion in most patients, and must be directed to the level of aortic and/or side branch obstruction.

Aortic Dissection↗
PubMed1994

Hydrodynamic performance of Carbomedics valves in double valve replacement.

Most patients undergoing double valve replacements have reduced myocardial capacity. However, little is known about the influence of valve sizes on myocardial energy consumption in double valve replacement. This study was designed to supply hydrodynamic data for the proper selection of sizes in double valve replacement. A mock loop system was used to measure the energy consumption of CarboMedics valves at conditions resembling rest (5 L/min) and moderate exercise (9 L/min). All combinations of aortic valves size #21 to #27 with mitral prosthesis sizes #25 to #29 were tested separately. Larger size aortic prostheses revealed remarkably less energy consumption up to size #27. Under high flow (9 L/min) this effect was more pronounced. In contrast, mitral valve prosthesis sizes #25 to #29 had similar hydrodynamic data. At low flow conditions (5 L/min) no significant benefit was found with the use of a larger mitral valve. Only a reduction of less than 10 percent of total energy consumption could be achieved with the use of a mitral valve larger than #25 at 9 L/min flow. In conclusion there is no hydrodynamic reason for using a valve larger than #25 in the mitral position for patients who exercise moderately. Continuous reduction of cardiac work can be expected with the use of the largest possible aortic prosthesis up to size #27 at rest and at moderate exercise.

Aortic Valve↗
PubMed1994

Surgical treatment of airway complications after lung transplantation.

The treatment of dehiscence or stenosis of the bronchus after lung transplantation has to date consisted of endobronchial stenting or balloon dilation. Operative intervention has been limited to retransplantation with all its limitations. In our series of 121 anastomoses at risk, severe bronchial stenosis occurred in 11 (9%). In five instances the airway complications were treated surgically: two patients underwent retransplantation, one patient had a bilobectomy, and two required sleeve resection of the stenotic segment. All these procedures successfully removed the stenosis. This experience demonstrates that options other than bronchial anastomotic stenting and dilation may be successfully used to overcome posttransplantation anastomotic complications. Conventional resections may result in superior long-term graft function compared with retransplantation, avoiding the immunologically adverse effects of the latter procedure.

Bronchi↗
PubMed1994

Risk of replacement of descending aorta with a standardized left heart bypass technique.

Replacement of the descending aorta for aneurysms (51%) and dissection (49%) was performed in 132 patients with a highly standardized left heart vortex-pump bypass. No adjuncts other than staged aortic clamping and intercostal artery reconnection were used to reduce spinal cord injury in extensive involvement. Four patients (3%) died early, two of cardiac cause, and nine (7%) died late. Complications of vital organ function occurred in eight patients, two having reversible renal failure and six spinal cord injury that was permanent in three (2.3%). Cord injury occurred only in replacement beyond thoracic segment 8 and could not be completely avoided despite distal intercostal artery reconnection in two cases; in the other four cases such vessels either did not appear worth reconnecting or were sacrificed in emergency operations. We conclude that left heart bypass effectively unloads the proximal circulation during aortic occlusion while maintaining adequate perfusion of distal vital organs as evidenced by low rates of early mortality and renal failure. The remaining risk of spinal cord damage may be lowered by more aggressive reconnection of all distal intercostal arteries and by extending the permissible cord ischemic period by means of hypothermia.

Adult↗
PubMed1994

Surgical treatment of active infective endocarditis with paravalvular involvement.

Aortic root infection remains a challenging problem in the surgical treatment of both native and prosthetic valve endocarditis. Between 1980 and 1991, 73 patients with active aortic valve endocarditis and paravalvular infection underwent operation. Indications for operation included congestive heart failure and uncontrolled sepsis. Aortic root abscesses were located in the noncoronary anulus or in the aorticomitral junction in 45% of cases, followed by the subannular interventricular septum in 23%. Two patients had an aorticoatrial fistula, seven an interventricular septal defect. Total or partial left ventricular-aortic dehiscence was observed in 27 patients. All patients underwent aortic valve replacement, nine with simultaneous mitral valve operations. Two of the latter required patch reconstruction of the destroyed aorticomitral septum with double valve replacement. Reconstruction of the aortic base was possible in 16 patients, whereas in 12 total replacement of the aortic root was necessary. In one patient, supracoronary aortic valve replacement was used. Recently, topical application of antibiotics in fibrin sealant was used in 25 patients. The operative mortality rate was 21% and correlated to preoperative uncontrolled sepsis and the presence of extensive root destruction. Operation for active endocarditis of the aortic root requires radical, individualized techniques and results in an acceptable operative and long-term risk. The use of an antibiotic fibrin compound appears to be a useful prophylactic tool to prevent postoperative residual endocarditis.

Abscess↗
PubMed1994

[Use of inferior epigastric artery for coronary artery bypass grafting].

Between 3/91 and 3/93 twenty-nine patients (pts.) with a mean age of 55 years (30-68) underwent CABG (including 3 reoperation) using inferior epigastric artery (IEA) in addition to internal thoracic artery and saphenous vein graft. IEAs were harvested as pedicles with a mean length of 12.2 cm (7.5-17). Overall distal anastomoses were performed 3.2 per patients. And a mean of 2.3 anastomoses were completed as an arterial graft. IEA grafts were applied to left anterior descending artery in 10, diagonal branch in 15, in marginal branches in 2 and right coronary artery in 2. Mean cardiopulmonary bypass time amounted to 103 minutes and operation procedures were completed in 258 minutes (mean). Aortic cross clamp time of 48 minutes were required. One patient was died of cerebral accident 23 days postoperatively. Except for two abdominal wall infection no wound healing problems occurred. One reexploration for bleeding were necessary. Postoperative angiography revealed patent IEA grafts in 12 of 13 patients (92%). We concluded that the application of IEAs for CABG is available as a third arterial graft and with respect to intraoperative management and perioperative complications use of IEA combined with ITAs appears suited or superior to the use of the right gastroepiploic artery.

Abdominal Muscles↗
PubMed1993

Lung transplantation.

The indications and results of single and double lung transplantation are described on the basis of 66 operations performed by the authors and on the background of the world literature. Lung transplantation is considered a new and promising therapeutic mode for treating patients with end-stage pulmonary failure related to fibrosis, emphysema, infective conditions, and pulmonary hypertension yielding satisfactory early results. The long-term prognosis of patients undergoing lung transplantation, like that of any other organ transfer, remains guarded.

Heart-Lung Transplantation↗
PubMed1993

Biophysical properties of the gelatin-resorcin-formaldehyde/glutaraldehyde adhesive.

Refixation of dissected aortic layers with gelatin-resorcin-formaldehyde/glutaraldehyde (GRFG) adhesive represents a new option in the surgical treatment of aortic dissection. Because of its ability to reinforce the delicate structures of the acutely dissected aortic wall, GRFG has been used increasingly in recent years. However, the biomechanical properties of the adhesive are still unclear, and little is known regarding the optimal mode of its application. In an ex vivo study, aortic specimens from sheep were glued with warm (45 degrees C) adhesive under wet and dry conditions and submitted to defined degrees of compression (5 Newtons [N], 20 N). Bonded specimens were retracted to assess tensile strength and elasticity compared with two reference adhesives: cyanoacrylate gel and fibrin glue. Gelatin-resorcin-formaldehyde/glutaraldehyde and cyanoacrylate gel showed similar results at 5 N. Both provided better adhesion when applied under dry conditions (GRFG 5 N: dry, 3.5 +/- 1.6 N/cm2; wet, 1.4 +/- 1.0 N/cm2; cyanoacrylate gel 5 N: dry, 4.8 +/- 1.8 N/cm2; wet, 3.2 +/- 1.3 N/cm2). At 20 N, GRFG tensile strength was significantly increased for either condition compared with values at 5 N (GRFG 20 N: dry, 17.1 +/- 4.2 N/cm2; wet, 4.8 +/- 1.8 N/cm2). Fibrin glue demonstrated only weak adhesive properties even under dry conditions (fibrin glue 5 N: dry, 0.8 +/- 0.3 N/cm2). Gelatin-resorcin-formaldehyde/glutaraldehyde has good adhesive properties both in wet and dry tissue. Bonding capacity can be substantially increased when applied on dry surfaces and at increased pressures.

Adhesiveness↗
PubMed1993

High incidence of aneurysm formation following patch plasty repair of coarctation.

Repair of aortic coarctation was performed in 152 adolescent and adult patients (mean age 28.5 years, range 14-67 years). Ninety patients were treated with patch plasty, 33 with end-to-end anastomosis, 18 with interposition of a tubular graft, 6 with prosthetic bypass and 5 with direct plasty. There were two (1.3%) early and ten (6.6%) late deaths after 2.9 to 11.8 (mean 6.6) years. Of the remaining 140 patients, 129 (92.1%) were reexamined with computed tomography and angiography after 1.5 to 17.2 (mean 9.1) years postoperatively. In 27 patients (35.1%) of the patch plasty group significant dilatation at the operative site was observed and reoperation for aneurysm formation was required in 15 patients (19.5%). Resection of the intimal crest did not increase the probability of aneurysm formation, whereas Dacron as patch material and late hypertension had a significant influence. Six of the ten late deaths occurred in the patch plasty group. Rupture of an aneurysm at the operative site was proved in two of these patients, and three patients died suddenly for unknown reasons. In the other groups significant dilatation was observed in 13 patients and 3 local aneurysms required reoperation (2 after end-to-end anastomosis and 1 after direct plasty). We conclude that patch plasty repair of coarctation should be abandoned in adults. End-to-end anastomosis is advisable only if possible without excessive tension. Reoperation with interposition of a tubular graft on left heart bypass proved to be a safe method.

Adolescent↗
PubMed1993

Chronic rejection following lung transplantation. Incidence, time pattern and consequences.

UNLABELLED: The long-term prognosis following lung transplantation (LTX) depends mainly on the development of chronic rejection which appears clinically as deterioration of the lung function while, histologically, obliterative bronchiolitis (OB) is found. However, it still remains questionable whether heart-lung (HL), double or single lung (DL/SL) transplants behave similarly with regard to incidence and time pattern. Eighty-two patients, transplanted until August 92, were analyzed. Early and late deaths within 180 days postoperatively were excluded. A total of 64 patients at risk could be evaluated. By repeated lung function tests, obstructive airway disease was defined by a drop of 25% or more of the forced expiratory volume in one second (FEV1) in percent of the inspiratory vital capacity. RESULTS: The functional optimum after transplantation was reached after a comparable time-span postoperatively in all groups. Chronic deterioration of the lung function developed earlier following DLTX compared to HLTX and SLTX. Obstructive airway disease was diagnosed in 9/20 (45%) HL, 7/19 (37%) DL, and 7/25 (28%) SL patients. Of these, 4 died and 4 had to be retransplanted for the disease while an additional 15 patients are currently under investigation. It is concluded that the development of obstructive airway disease represents a serious problem in all types of lung transplantation. There is a tendency to earlier development following DLTX--perhaps caused by the greatest immunological potential in this group of patients.

Adult↗
PubMed1993

Implantation of the automatic implantable cardioverter defibrillator for coronary artery disease--surgical experience in 185 patients.

The results in 185 patients with coronary artery disease undergoing implantation of an automatic implantable cardioverter defibrillator (AICD) were reviewed with regard to the operative technique applied and problems observed. In 123 patients (group I) only AICD implantation was performed. Ninety patients were operated through sternotomy or thoracotomy while in 33 patients an endovenous/subcutaneous technique was used. Sixty-two patients (group II) underwent simultaneous coronary artery bypass grafting (CABG) and AICD implantation by median sternotomy. Perioperative mortality was 2.4% in group I with one fatality in the subgroup of endevenous/AICD placements and 11.3% in group II (p < 0.01). Overall infectious complications were low with 2 removals in group I and 1 in group II; however, no infections were observed after endovenous system implantation. It is concluded that the operative mortality rate of a combined approach is significantly higher, when compared to isolated AICD placement. However, the greater risk of the former cohort is mainly due to the impaired ventricular performance. Further investigations will have to prove whether a two-step approach using the endovenous technique in patients with a need for AICD and CABG will reduce the operative mortality.

Adult↗
PubMed1993

Comparative in vivo study on the healing qualities of four different presealed vascular prostheses.

PURPOSE: The purpose of this article is to assess the healing qualities of presealed knitted polyester prostheses. METHODS: Thoracic aortic replacement was performed with grafts with four different coating materials-collagen (CP), albumin (AP), and two with gelatin (GP1/GP2)-in four groups of 15 pigs each. Two weeks, 6 weeks, and 6 months after operation, five pigs of each group were killed. Healing quality was assessed by morphometric analysis of the remaining coating, the extent of tissue ingrowth, and the thickness of the inner layer. RESULTS: The sealant was rapidly absorbed in all prostheses except for the AP (remaining coating at 2 weeks: GP1 22.1%, GP2 34.7%, and CP 68.0% vs AP 97.1% [p < 0.05]), remaining coating at 6 weeks: GP1/GP2 0% and CP 2.5% vs AP 76.7% (p < .01). At 6 months, remaining coating was only detectable in AP (21.5%). At 2 weeks the extent of tissue ingrowth ranged from 65.7% in GP1 and 75.3% in CP to 80% in GP2 versus 8.9% in AP (p < 0.05). There was a slow increase of tissue ingrowth until the sixth postoperative week (GP1 74.4%, GP2 85.0%, and CP 91.3% versus AP 19.6% [p < 0.01]). Thickness of the internal layer varied from 0.11 to 0.21 mm at 2 weeks in all grafts studied and from 1.02 mm (AP) and 1.28 mm (GP2) to 1.39 mm (GP1), versus 0.41 mm in the CP (p < 0.01) after 6 months of implantation. CONCLUSIONS: The type of coating significantly influences the healing properties of knitted polyester prostheses. When used for thoracic aortic replacement in pigs, AP coating clearly results in inferior healing compared with GP1/GP2 or CP impregnation, with digestion of the coating material and tissue ingrowth used as parameters. The thinnest internal layer was found in the CP prostheses, reflecting superior healing properties of this coating in the model studied.

Absorption↗