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Biomedical subjects

M Karck

Publications and source records attributed to M Karck.

54 records · Page 3Linked to original sources
PubMed1992

Staged chest closure in pediatric cardiac surgery preventing typical and atypical cardiac tamponade.

Chest closure after cardiac surgery occasionally results in cardiac compression leading to circulatory failure. In shunt-dependent circulation, the arterial oxygen saturation may decrease significantly due to the increase in pulmonary vascular resistance caused by chest closure. Temporary patch implantation with delayed sternal closure facilitates circulatory and/or pulmonary stabilization (temporary chest wall patch plasty, TCWPP). Between July 1986 and June 1991, 42 patients underwent staged chest closure (TCWPP) after open heart surgery for congenital lesions (4.9% of 854 patients). TCWPP was performed when either primary hemodynamic deterioration or an increase in cyanosis (palliative procedures only) followed by hemodynamic deterioration occurred during attempted or shortly after sternal closure. Overall mortality was 40.4% (17/42). It was 32.3% (11/34) when the patch was inserted primarily at the end of the operation. If the patch was inserted emergently 4-24 h postoperatively, mortality was 75% (6/8). Definite chest closure was performed from 4 h to 6 days (mean 72 h) postoperatively. In 2 patients closure had to be performed emergently (single ventricles); 7 patients died before chest closure. One mediastinal microbiology examination was positive. Deep sternal infection necessitating operative revision occurred in one other patient. In conclusion, TCWPP may considerably lower mortality of the illest patients after surgery for complex congenital heart disease. A timely decision as to the performance of staged chest closure is mandatory. This procedure rarely causes infection. We now apply this technique liberally, by cardio-mediastinal size judgement in over 30% of our TCWPP candidates even without a prior trial of primary closure.

Adolescent↗
PubMed1992

Prolonged myocardial protection with St. Thomas' Hospital solution and University of Wisconsin solution. The importance of preservation techniques.

The effectiveness of University of Wisconsin solution (UWS) and oxygenated St. Thomas' Hospital solution (STS) for prolonged myocardial protection was evaluated in isolated working rat hearts preserved for 12 h at 4 degrees C using three different preservation techniques: induction of cardiac arrest and subsequent hypothermic storage with STS (group 1, n = 9) or UWS (group 4, n = 9), intermittent coronary flush (every 90 min) with STS (group 2, n = 9) or UWS (group 5, n = 9), or continuous coronary perfusion with STS (group 2, n = 7) or UWS (group 6, n = 7) before 60 min of reperfusion. In the UWS preserved hearts, recovery of aortic flow was greater when the simple storage technique was employed compared to intermittent or continuous coronary perfusion (groups 5 and 6). In the STS preserved hearts, aortic flow recovery was superior when the intermittent perfusion technique was applied. The same pattern was observed with regard to recovery of left ventricular pressure. Lactate dehydrogenase release during reperfusion was significantly less pronounced in group 4 (UWS, single flush, simple storage) as compared to group 1 (STS, single flush and simple storage), whereas best preservation of myocardial high energy phosphates was observed when hearts were preserved with multiple dose cardioplegia using STS. Simple hypothermic storage with UWS affords the best functional recovery after prolonged myocardial ischemia in all groups. Repetitive or continuous application of this solution is detrimental, possibly due to potassium overloading. In STS treated groups, multiple dose application of oxygenated STS enhances functional and metabolic recovery compared to its single dose application.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1992

Prevention of graft infection by bonding of gentamycin to Dacron prostheses.

To increase the efficacy of perioperative antibiotic prophylaxis in vascular surgery an experimental study including topical application of the gentamicin derivative EMD 46/217 and fibrin sealant as antibiotic carrier to Dacron prostheses was initiated. In vitro treatment of Dacron with gentamicin and fibrin was followed by constant antibiotic release for 3 weeks. In a subsequent animal study Dacron grafts were implanted in the aorta of 10 pigs after direct contamination with Staphylococcus aureus solution. One graft was pretreated with the antibiotic/fibrin compound, a second with the antibiotic alone. Grafts 3 (no pretreatment) and 4 (fibrin alone) served as controls. After 1 week the grafts and their corresponding implantation sites were excised for measurement of antibiotic content and for culture. The antibiotic content of grafts with the antibiotic/fibrin compound was 25.0 +/- 7.2 micrograms/gm wet weight, whereas Dacron pretreated with the antibiotic alone contained no measurable drug amounts except for one specimen (0.5 microgram/gm) (antibiotic/fibrin vs antibiotic, p less than .0005). The corresponding implantation sites to antibiotic/fibrin grafts contained 1.07 +/- 0.54 microgram/gm antibiotic, whereas in only 2/10 implantation sites of antibiotic grafts low antibiotic levels were found (0.05 and 0.2 microgram/gm) (antibiotic/fibrin vs antibiotic, p less than 0.005). All control grafts and 9/10 antibiotic grafts were infected. By contrast, only five were contaminated, and 5 of 10 remained sterile after culture (antibiotic/fibrin vs antibiotic, p less than 0.05). This finding correlates with the antibiotic content in the Dacron. It is concluded that pretreatment of prosthetic Dacron grafts with the antibiotic/fibrin compound results in binding of sufficient amounts of antibiotic for at least 1 week.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

[Complex progressive palliation for univentricular circulation].

The type of palliative procedures (PP) for complex univentricular circulation (UC) changed significantly during the 80ies. Between 07/86 and 02/91 77 patients (pts) presented with UC to eventually undergo a modified Fontan-Kreutzer-type-operation (MFKTO). 33 pts had been previously palliated, 22 of whom were accepted for MFKTO as well as an additional 9 not palliated pts (group A: 31 pts; 20 PP). 11 previously palliated pts and 35 new pts required new palliations (group B: 46 pts; 89 PP), 34 of which resulted in 13 MFKTO. Prerequisites to be met for MFKTO are: undistorted PA-anatomy; absence of subaortic stenosis (SAS); Qp greater than 2.5 l/min/m2; PAP less than 20 mm Hg; Rp less than 3 Wood Units. All earlier PP in group A (31 BTS, 3 PAB, 2 PA-valvotomy/dil.) merely prolonged survival by only adjusting Qp. In group B PP comprise reconstruction of pulmonary arteries, aortic arch and isthmus as well as bypass or resection of SAS or atrial septectomy. Mortality for complex PP (group B) was 32.5% (15/46). 9 of these pts were neonates, 7 after modified Norwood procedures. In an attempt to plan a MFKTO for all pts presenting with UC (group B), complex PP was necessary. The high mortality is due to lesions in pts who would not have survived if only closed PP were applied.

Child↗
PubMed1992

The effectiveness of University of Wisconsin solution on prolonged myocardial protection as assessed by phosphorus 31-nuclear magnetic resonance spectroscopy and functional recovery.

The effectiveness of the University of Wisconsin solution on extended myocardial preservation was examined in this study using phosphorus 31-nuclear magnetic resonance spectroscopy. Isolated perfused rat hearts were arrested and stored in four preservation solutions: group 1, modified Krebs-Henseleit solution; group 2, modified St. Thomas' Hospital solution; group 3, oxygenated modified St. Thomas' Hospital solution containing 11 mmol/L glucose; and group 4, University of Wisconsin solution. The changes in myocardial high energy phosphate profiles and the intracellular pH values were measured during 12 hours of cold (4 degrees C) global ischemia and 90 minutes of normothermic reperfusion. Following ischemia, the hearts were assessed for hemodynamic recovery and myocardial water content. During ischemia, adenosine triphosphate depletion was observed in all groups; however, after 5 hours of ischemia, the adenosine triphosphate levels were significantly higher in group 3 compared with the other groups (adenosine triphosphate levels at 6 hours in mumol/gm dry weight: group 3, 7.6; group 4, 3.2; group 2, < 1; p < 0.025). The tissue water content at the end of ischemia was lower with the University of Wisconsin solution compared with the modified St. Thomas' Hospital solution or the oxygenated modified St. Thomas' Hospital solution (in ml/gm dry weight: group 4, 3.0; group 2, 4.4; group 3, 3.9; p < 0.05). The adenosine triphosphate repletion during reperfusion was greater with the University of Wisconsin solution compared with the modified St. Thomas' Hospital solution or the oxygenated modified St. Thomas' Hospital solution (12 mumol/gm dry weight in group 4; 8.1 in group 2; 9.0 in group 3; p < 0.05). Similar findings were obtained for the recovery of left ventricular pressure (in percent of preischemic control: group 4, 70%; group 2, 42%; group 3, 52%; p < 0.01) and coronary flow (group 4, 61%; group 2, 49%; group 3, 49%; p < 0.05). These data suggest that preservation with the University of Wisconsin solution affords improved hemodynamic recovery, enhanced adenosine triphosphate repletion, and reduced tissue edema upon reperfusion; however, oxygenated St. Thomas' Hospital solution with glucose is associated with the preservation of higher myocardial adenosine triphosphate levels during prolonged cold global ischemia. In conclusion, these data indicate that the University of Wisconsin solution might improve graft tolerance of ischemia in clinical heart transplantation.

Adenosine↗
PubMed1992

Long-term follow-up after separate replacement of the aortic valve and ascending aorta.

Between May 1974 and November 1991, 28 patients underwent a separate replacement of the aortic valve and the ascending aorta (20 male, eight female; 32 to 71 years old, x = 52 years). 23 patients were operated for ascending aortic aneurysm, three for chronic and two for acute aortic dissection type A. 17/18 patients living at the beginning of this study were re-investigated after a mean follow-up interval of 8.5 years postoperatively with DSA, thoraco-abdominal CT and echocardiography. 1/8 biological aortic valves and 1/20 mechanical valves had to be replaced (four years and two months postoperatively) for valve degeneration and paravalvular leakage respectively. Three patients developed a sinus of Valsalva aneurysm and were reoperated five, 9.2 and 9.3 years after primary repair. In all three patients histological signs of idiopathic degenerative media disease of the aorta were found. Two other patients presented with a perfused perigraft channel and therefore had to be reoperated. Patients with chronic aortic dissection type A and/or ascending aortic aneurysms presenting clinical or intraoperative signs of degenerative media disease of the aorta should undergo composite graft replacement to preclude formation of sinus Valsalva aneurysms.

Adult↗
PubMed1992

An improved method for endothelial cell seeding on polytetrafluoroethylene small caliber vascular grafts.

The creation of nonthrombogenic synthetic surfaces is a major challenge in biomedical research. The feature that clearly distinguishes natural blood vessels from their artificial counterparts is the presence of endothelial cell lining that besides being nonthrombogenic is capable of repair and renewal. This study describes a method of coating vascular grafts with a uniform, naturally produced subendothelial extracellular matrix before implantation. This substrate provides a most suitable bilayer for endothelial cell adhesion, growth, and differentiation, as compared with grafts coated with fibronectin or basement membrane extracts. It contains both adhesive glycoproteins (fibronectin, laminin, collagen) and proteoglycans (heparan sulfate) as well as endothelial cell growth factors (basic fibroblast growth factor) that support adhesion and normal growth of suboptimal concentrations of endothelial cells. We suggest that the presence in extracellular matrix of both adhesive macromolecules and potent endothelial cell-growth promoting factors will make the extracellular matrix a promising substrate for vascular grafts.

Animals↗
PubMed1992

[31-phosphor-NMR spectroscopy for determining optical preservation temperature during long-term myocardial ischemia].

The ideal level of hypothermia during myocardial preservation for cardiac transplantation remains unknown. Therefore 31P-NMR spectroscopy was applied to assess the effect of different preservation temperatures (15 degrees C in group 1, 4 degrees C in group 2) on time dependent changes of myocardial high energy phosphorous compounds during prolonged global ischemia (5 hours in group 1, 8 hours in group 2) and subsequent reperfusion of isolated rat hearts preserved with modified St. Thomas Hospital solution. ATP-depletion during ischemia was slower in group 2 leading to a significant difference in myocardial ATP-concentrations between both groups after 3 hours of ischemia. The drop of intracellular pH during ischemia was significantly less pronounced in hearts preserved at 4 degrees C compared to 15 degrees C. Postischemic recovery of both left ventricular (LV) peak systolic pressure and its +dP/dt max. was superior in group 2, although the ischemic time was 3 hours longer than in group 1. Hypothermia at 4 degrees C appears favourable for prolonged myocardial protection compared to 15 degrees C with regard to preservation of ATP, prevention of intracellular acidosis and postischemic hemodynamic recovery.

Adenosine Triphosphate↗
PubMed1991

Surgery extended into the aortic arch in acute type A dissection. Indications, techniques, and results.

From May of 1979 to September of 1990, 106 patients underwent emergency surgery for acute type A aortic dissection. In 29 patients (27.3% of total; mean age, 53 years) surgery was extended into the aortic arch. In 19 cases the proximal entry reached or began beyond the aortic cross-clamping site, which prevented proper reconstruction of the distal aorta. In six cases an aortic perforation was located in the arch. In four others the dissection occurred within a preexistent arch aneurysm. Operative techniques consisted of eight arch reconstructions, 17 proximal arch replacements, and four total arch replacements. Repair was performed during deep hypothermia (mean nasopharyngeal temperature, 17.8 degrees C) and circulatory arrest (mean, 24.2 minutes). Operative mortality was 20.6% (six of 29), dropping to 10.5% (two of 19) during the past 4 years. There were no late deaths in the 23 survivors, with one patient suffering from neurological sequelae. Nineteen underwent either computed tomography and digital subtraction angiography or magnetic resonance imaging without pathological findings in the ascending aorta or arch. In acute type A aortic dissection the site of the intimal tear and/or perforation, as well as preexistent aneurysmatic disease, may require primary aortic arch repair. This can be accomplished during deep hypothermia and circulatory arrest, with acceptable early and satisfactory late results.

Aortic Dissection↗
PubMed1990

Thoracic aortic aneurysms after acute type A aortic dissection: necessity for follow-up.

Between April 1979 and May 1989, 86 patients underwent emergency operation for acute type A aortic dissection. Sixty-four (74.4%) survived. None of the survivors died of late aortic complications. Fifty-eight patients were followed 3 months to 10 years (mean follow-up, 3.2 years) postoperatively with computed tomography and digital subtraction angiography. Dilatation of the distal aorta (diameter size range, 6 to 10.5 cm) developed in 10 patients (17%). Six patients underwent replacement of the descending aorta 1 month to 21 months (mean period, 8.5 months) after aortic dissection repair. Two of them had third-stage thoracoabdominal replacement. In 2 patients, replacement of the descending aorta was scheduled; 1 died before reoperation and 1 refused the procedure. Two patients underwent aortic arch replacement; it is scheduled for another (fourth stage). There were no deaths among the patients having reoperation. The rate of indications for reoperation on the aorta downstream from the original repair 1 month to 6 years 4 months (median time, 9 months) after primary surgical intervention for acute type A aortic dissection was 24% (14 reoperations in 10 of 58 patients). This study underscores the importance of close follow-up of patients having operation for acute type A aortic dissection. Early recognition of progressive downstream aortic pathology permits effective prevention of aortic rupture and timely reoperation.

Adult↗
PubMed1990

Pretreatment of prosthetic valve sewing-ring with the antibiotic/fibrin sealant compound as a prophylactic tool against prosthetic valve endocarditis.

Prosthetic valve endocarditis (PVE) remains a dreaded complication following heart valve replacement despite perioperative antibiotic (AB) prophylaxis. In order to increase the AB concentration in the sewing ring, an experimental study including topical application of the gentamicin derivative EMD 46/217 and fibrin sealant (F) as AB-carrier was initiated. In vitro pretreatment of Dacron with the gentamicin derivative and F was followed by constant AB release for 3 weeks. In a subsequent animal study, four Dacron rings with different pretreatment were implanted in the descending aorta of 10 pigs after direct contamination with 10(8) Staphylococcus aureus solution. One ring was pretreated with the AB/F compound, a second ring with the AB alone. Ring 3 (no pretreatment) and ring 4 (F alone) served as controls. After 1 week, the sewing rings and their corresponding implantation sites were assayed for measurement of AB-content and for culture. The AB content of AB/F-rings was 24.99 +/- 7.16 micrograms/g wet weight, while rings pretreated with the AB alone contained no measurable drug amounts with the exception of one specimen (0.5 microgram/g) (AB/F vs. AB-rings: P less than 0.0005). The corresponding implantation sites to AB/F rings contained 1.07 +/- 0.54 micrograms/g AB, whereas in only 2 of 10 implantation sites of AB rings, low AB levels were found (0.05 and 0.2 micrograms/g) (AB/F vs. AB ring implantation sites: P less than 0.0005). While all control rings and 9 of 10 AB rings were infected, 5 of 10 AB/F rings remained sterile after culture (AB/F vs. AB rings: P = 0.05). This finding correlated with the AB content in the suture rings.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1990

[Postoperative diagnosis following separate replacement of an aortic valve and an ascending aorta using IV-DSA and CT].

We performed a follow-up examination by intravenous DSA and dynamic CT of 14 patients with separate replacement of aortic valve and ascending aorta due to an aneurysm or an aortic dissection. In 5 patients, we found an aortic ectasia at the aortic bulb or a perfused "graft inclusion". Both are best demonstrated with dynamic CT. As a result of the study, the operation technique was changed. In the postoperative management of patients with separate replacement of aortic bulb and ascending aorta, careful monitoring by dynamic CT is necessary even in the absence of clinical symptoms.

Adult↗
PubMed1990

[After care and reoperation after primary intervention in chronic type A aortic dissection].

UNLABELLED: Between 4/78 und 9/89 44 patients (pts.) underwent primary repair of CADA. 3 pts. died early postoperatively. 36 pts. were followed-up 3 months to 9.7 years (means = 3.1 years) postoperatively with CT, DSA and echocardiography. 8 pts. underwent 12 aortic reoperations, in 10 cases due to persistent or recurrent aneurysms. CONCLUSIONS: In CADA radical replacement of the Ascending Aorta is advisable to prevent recurrent aneurysms formation. Systematic follow-up facilitates early recognition and repair of progressively chronic or new downstream aortic pathology.

Adult↗
PubMed1989

Intravenous DSA and dynamic computed tomography for postoperative follow-up of type A aortic dissections.

We undertook a direct comparison of intravenous digital subtraction angiography and dynamic computed tomography in a follow-up study on 37 patients who had undergone surgery on the thoracic aorta for acute or chronic type A dissections. These are minimally invasive and complementary procedures: IV-DSA provides a clear angiographic image of the dissection, with visualization of the true and false channels, their distal extension and the supra-aortic and abdominal vessels they supply. Dynamic CT best demonstrates the proximal extension of the disease; it visualizes clotting in the false lumen and permits a more accurate measurement of the aortic width, and thus early recognition of a developing aneurysm.

Adult↗
PubMed1985

Establishment of thymidine kinase (EC 2.7.1.21)-deficient mutants of human monocytic cell line U-937.

Using morphologic, enzyme-cytochemical, and immunocytochemical methods, the functional diversity of the mononuclear phagocyte system can be studied only to a limited extent. Therefore, enzyme-deficient monocyte/macrophage cell lines have been established as technical prerequisites for the generation of monocyte/macrophage hybrids by applying selective media. After mutation with ethylmethanesulfonate, six clones of U-937 were selected against increasing concentrations of 5'-bromodesoxyuridine; these clones are defective in thymidine kinase (EC 2.7.1.21), as shown by autoradiography and direct measurement of [3H]thymidine uptake. A broad marker panel indicates that the clones could be appropriate for the establishment of human monocyte/macrophage hybrids.

Cell Line↗
PubMedDate not supplied

TPEN, a transition metal chelator, improves myocardial protection during prolonged ischemia.

In view of the hypothesis that free radicals induced damage during ischemia and reperfusion is mediated by transition metals, we investigated the effect of the potent metal chelator TPEN (N,N,N'N'-tetrakis(-)[2-pyridylmethyl]-ethylenediamine) on cardiac function after prolonged myocardial ischemia. Isolated working rat hearts were subjected to 12 hours of cold ischemic arrest followed by reperfusion for 1 hour. The study was carried out on five groups (nine hearts in each): (1) St. Thomas' Hospital cardioplegic solution; (2) St. Thomas' Hospital cardioplegic solution with 7.5 mumol/L TPEN; (3) protection conditions as in group 2, but with TPEN administration during preischemic and reperfusion periods; (4) University of Wisconsin solution; and (5) the same conditions as in group 4 with TPEN administration during the preischemic and reperfusion periods. Significant enhancement of hemodynamic recovery was observed in the presence of TPEN throughout the experiment. The recovery of cardiac output was 24% +/- 4% in group 3, as compared to 12% +/- 4% in group 1 (p < 0.01). The postischemic left ventricular pressure recovery was 57% +/- 4% in group 3, as compared to 18% +/- 7% in group 1 (p < 0.005). The hearts in group 5 recovered, reaching 29% +/- 2% of the preischemic cardiac output and at 65% +/- 2% of the left ventricular pressure recovery (p < 0.05 versus group 3). Lactate dehydrogenase was released throughout the reperfusion. TPEN addition to groups 2 and 3 did not significantly reduce lactate dehydrogenase release; however, TPEN in University of Wisconsin solution and throughout the experiment significantly decreased lactate dehydrogenase release.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗