Biomedical subjects

M Karck

Publications and source records attributed to M Karck.

At least 19 recordsLinked to original sources

PubMed2006

Minimally invasive repair of pectus excavatum - shifting the paradigm?

PURPOSE: The "minimally invasive repair of pectus excavatum" (MIRPE) has increasingly become the standard operation for the repair of pectus excavatum. The aim of the present study was to report on our first-line postoperative results, including a survey of patients and to elucidate the acceptance of MIRPE. PATIENTS AND METHODS: All MIRPE patients, who were operated on between 2000 and 2004 in our departments, were included in a retrospective study. In 2002, a retrospective questioning of 57 patients was initiated by sending identical questionnaires separately to both the patients and their parents asking for individual reasons for choosing and/or agreeing to MIRPE. RESULTS: Complications were seen in 25 out of 84 MIRPE patients (mean 14 years, range from 5 to 20 years), but most of them were minor. Removal of the bar was necessary in 6 cases, due to bar displacement, secondary haematothorax, pericardial effusion, and local infection, respectively. No major complications occurred in the age group between 9 and 14 years. More than 90 % of the patients and their parents were satisfied or highly satisfied with the MIRPE procedure. CONCLUSION: General and specific complications are similar to other series and they decrease with the surgeon's experience. The most severe problem, occurring in older patients, is how to avoid dislocation of the pectus bar. In the light of the complication rate, the acceptance of MIRPE is still high, especially in adolescents and young adults who had refused operation with the open techniques. In this way, a shifting of a paradigm is taking place.

Adolescent↗

PubMed2006

[In vivo detection of integration of grafted cells after myocardial transplantation].

Myocardial transplantation of myocytes and bone marrow derived cells is currently under clinical evaluation as an alternative therapy of heart failure. One of the main problems of all clinical studies performed so far is the inability to track the fate of the transplanted cells. The aim of our study was the development of a potentially clinically applicable approach, which allows for detection of the transplanted cells without need for collection of tissue samples. Fetal canine cardiomyocytes were labelled with the non-toxic fluorescent membrane dye Vybrant CM-DiI and delivered into the free wall of the left ventricle of adult mongrel dogs. For subsequent tracking of the cellular graft, the dogs underwent a second operation in which an intra-vital microscope was mounted above the exposed heart within the thorax. A special computer software eliminated artefacts caused by myocardial contraction. Two months after transplantation, the fluorescent graft was macroscopically visible by intra-vital microscopy using a 10x magnification. Histological studies served as microscopic control and confirmed the existence of DiI-labelled cells at the site of injection. Connexin 43 immunoreactivity was visible at junctional complexes between donor and recipient cells, suggesting morphologic and functional coupling as a result of gap junction formation. Our results demonstrate that in vivo detection of transplanted cells in the heart is feasible. Further technical adjustments should allow for thoracoscopic/endoscopic application of this method, making it appropriate for use in other organs and in clinical studies.

Animals↗

PubMed2005

[Cardiac surgery in elderly patients].

Due to demographic changes in average life expectancy, the age of patients undergoing cardiac surgery is increasing. We have reviewed the literature to analyse whether and how far octogenarians benefit from cardiac surgical procedures. Different studies analysed the outcome of patients in different age groups after cardiac surgery. Octogenarians can undergo cardiac surgical procedures at a reasonable risk. The perioperative mortality and other postoperative complications are strongly dependent on comorbidities rather than on patients' age. Elderly patients benefit from improved functional status and quality of life.

Age Factors↗

PubMed2004

Acute aortic dissection versus aortic root aneurysm: comparison of indications for valve sparing aortic root reconstruction.

OBJECTIVES: To prove whether different indications for valve sparing aortic root reconstruction may have an impact on the outcome and longevity of the repair. METHODS: From July 1993 to March 2003, the reimplantation technique for valve sparing aortic root reconstruction was applied to 232 patients. In 44 patients, indication for operation was acute aortic dissection type A (AADA). These patients were compared with 44 randomised patients operated for aortic root aneurysm (root) by matched pair analysis with respect to age, gender, time point of operation and presence of Marfan's syndrome. Peri- and post-operative courses with focus on survival and valvular stability were analysed. RESULTS: Pre-operative grade of aortic insufficiency was 2.4+/-1 in root vs. 1.5+/-1.7 in AADA (P = 0.004) Mean CPB-time (214+/-60 vs. 171+/-42 min;P < 0.001), aortic cross clamp time (158+/-40 vs. 129+/-39 min; P = 0.001) and stay on ICU (5.2+/-9 vs. 1.7+/-1 days; P = 0.034) were longer for AADA, while hospitalisation was comparable (14+/-10 vs. 14+/-7 days; P = 0.88). Five patients (11.4%) from AADA died peri-operatively compared to no patient from root (P = 0.055). None of the early deaths were valve-related. Re-thoracotomy rate was 6.8% for both groups. Mean follow-up was 19+/-21 months for AADA vs. 28+/-21 months for root (P = 0.038) Survival at 3 years was 88+/-5% for AADA and 100% for root (P = 0.028). Freedom from valvular reoperation was 97+/-2.7% for root and 97+/-3% for AADA at 3 years (P = 0.44). At last investigation, mean grade of aortic insufficiency for AADA was 0.2+/-0.3 compared to 0.3+/-0.3 for root (P = 0.34) CONCLUSIONS: Regardless of the underlying indication, the aortic valve preserving reimplantation technique can be performed with favourable functional results.

Acute Disease↗

PubMed2003

Impact of preoperative aortic root diameter on long-term aortic valve function after valve sparing aortic root reimplantation.

BACKGROUND: Valve sparing aortic root reimplantation technique in patients with aortic root aneurysm have shown excellent mid-term results. In conjunction with the diameter of the aortic root the mechanical leaflet stress increase, which might have an impact on long-term aortic valve function after valve sparing aortic root reimplantation. METHODS AND RESULTS: From July 1993 to October 2001, 168 patients with aortic root aneurysm underwent valve sparing aortic root reimplantation. Patients with type A aortic dissection were excluded. Thus, 123 patients were analyzed. We identified 47 patients with an preoperative aortic root diameter exceeding 60 mm (group A), 58 patients with an diameter between 50 and 60 mm (group B), and 18 patients with a diameter less than 50 mm (group C). The groups were compared regarding mortality, long-term survival, freedom from reoperation, freedom from severe and moderate aortic valve insufficiency (AI), and postoperative morbidity. Mean follow-up (group A 43+/-26 months, group B 40+/-25 months, group C 23+/-19 months; group C versus group A, P=0.005; group C versus group B, P=0.011) was shorter in group C. Perioperative mortality (group A 2.2%, group B 1.9%, group C 5.2%; P=ns) was comparable between the groups with each one patient. The 3-year survival for group A was 98+/-2%, for group B 96+/-3%, and for group C 100+/-0% (P=ns). Freedom from reoperation for group A was 98+/-2%, for group B 96+/-3%, and for group C 88+/-8% (P=ns). Four patients developed severe or moderate AI, thus freedom from severe and moderate AI for group A was 100+/-0%, for group B 88+/-8%, and for group C 94+/-5% (P=ns). During follow-up no thromboembolic or bleeding events were noticed. CONCLUSIONS: Our data show that the preoperative diameter of the aortic root has no impact on the longevity of the repair. Thus, the reimplantation technique can be recommended for all patients presenting with an aortic root aneurysm and normal leaflets regardless of the aortic root diameter.

Adult↗

PubMed2003

[Ross procedure with combined replacement of the ascending aorta: impact on autograft root function and distensibility].

BACKGROUND: The safety and effectiveness of combined aortic root autograft replacement in combination with ascending aorta replacement has been demonstrated recently. Replacement of the ascending aorta with a vascular prosthesis results in an increase in aortic root distension, and aortic root wall stress. In this study we aimed to assess the autograft root dimensions, distensibility, and autograft valve function in patients after Ross operation combined with replacement of the ascending aorta compared to patients who underwent Ross operation only. PATIENTS AND METHODS: Echocardiographic follow-up was performed on 28 patients after Ross operation with complete root replacement only (group R) and 12 patients who received an additional replacement of the ascending aorta (group R/A). The mean follow-up time was 24.9 +/- 17.2 months. Autograft root dimensions, root distensibility and valve function were assessed by echo-cardiography. The aortic root was measured at the level of the annulus, sinus of valsalva, and sinotubular junction. The distensibility was calculated as percent change of radius. RESULTS: The mean distensibility at the annulus level was higher in group R/A (18.4 +/- 6.8% vs 13.4 +/- 8.1%; p = 0.047); at the level of the sinus of valsalva and sinotubular junction no differences were observed. The autograft pressure gradient was within physiological limits in all patients. The majority of patients showed a competent autograft valve (group R: AI 0 degree; 83%, AI I degree; 14%, AI II degree; 3%; group R/A: AI 0 degree; 75%, AI I degree; 25%). CONCLUSIONS: Replacement of the ascending aorta with a non-compliant prosthesis does not effect root dimension, distensibility, and valve function.

Adult↗

PubMed2001

The push-and-pull mechanism to scavenge redox-active transition metals: a novel concept in myocardial protection.

OBJECTIVE: Traces of redox-active transition metals such as iron and copper play an important role in free radical formation during postischemic reperfusion of the heart. Two studies were conducted to assess the efficacy of the complexes of desferrioxamine with zinc or gallium to prevent this aspect of reperfusion injury. METHODS: In study I, isolated working rat hearts (n = 96) were subjected to 2 hours of hypothermic arrest at 10 degrees C induced by use of St Thomas' Hospital cardioplegic solution II supplemented with desferrioxamine, zinc-histidinate, zinc-desferrioxamine, gallium-nitrate, or gallium-desferrioxamine. In study II, isolated nonworking rat hearts (n = 23) were subjected to normothermic regional (10 minutes) or global (35 minutes) unprotected ischemia. In this study, the perfusate was supplemented with gallium-desferrioxamine during preischemic and postischemic periods. RESULTS: In study I, the addition of desferrioxamine, zinc-histidinate, or gallium-nitrate to St Thomas' Hospital solution II improved postischemic aortic flow recovery. When the binary complexes zinc-desferrioxamine or gallium-desferrioxamine were added, however, functional recovery was further enhanced significantly. In study II, high-performance liquid chromatography analyses of tissue from postischemic hearts exposed to unsupplemented perfusate revealed a marked increase of malondialdehydes. In hearts perfused with perfusate supplemented with gallium-desferrioxamine, however, tissue malondialdehyde concentrations were significantly smaller, indicating reduced free radical formation. CONCLUSIONS: The data suggest synergistic protection by the complexes of the iron chelator desferrioxamine with zinc or gallium. The single components neutralize transition metals by 2 different but complementary push-and-pull mechanisms, thereby leading to an inhibition of metal-mediated site-specific free radical formation and improvement of postischemic cardiac function.

Analysis of Variance↗

PubMed2001

Myocardial protection by ischemic preconditioning and delta-opioid receptor activation in the isolated working rat heart.

OBJECTIVE: delta-Opioid receptors are involved in the cardioprotective effect of ischemic preconditioning. This study was designed (1) to assess the protective capacities of ischemic preconditioning and the synthetic delta-opioid receptor agonist D-Ala(2)-D-Leu(5) enkephalin (DADLE) in a functionally oriented experimental model of ischemia and reperfusion and (2) to assess whether the effects of both protective measures are similarly blocked by naloxone, a nonspecific delta-opioid receptor antagonist. METHODS: Sixty-four isolated working rat hearts were subjected to 45 minutes of hypothermic ischemia at 30 degrees C followed by 25 minutes of normothermic reperfusion. Rats were pretreated with DADLE (1 mg/kg body weight intravenously), naloxone (3 mg/kg body weight intravenously), or a combination thereof within 60 minutes before onset of isolated heart perfusion. During the preischemic perfusion period, 8 hearts per group were preconditioned by one cycle of 5 minutes of normothermic global ischemia and subsequent reperfusion whereas another 8 served as nonpreconditioned controls. The postischemic functional recovery of hearts and their creatine kinase leakage were determined. RESULTS: Pretreatment with DADLE and ischemic preconditioning improved the postischemic recovery of aortic flow when compared with nonpreconditioning (57.7% +/- 4.0% and 60.8% +/- 4.3% vs 40.0% +/- 4.2% of preischemic baseline value, P <.001). Combined pretreatment with DADLE before ischemic preconditioning afforded additional aortic flow recovery compared with pretreatment with DADLE alone (68.6% +/- 3.3% vs 57.7% +/- 4.0% of preischemic baseline value; P =.038). With combined pretreatment, early postischemic creatine kinase release was lower than control in hearts without pretreatment (0.48 +/- 0.11 vs 0.80 +/- 0.12 IU/5 minutes per heart; P =.001). Naloxone abolished the beneficial functional effects of pretreatment with DADLE and ischemic preconditioning. CONCLUSIONS: Pharmacologic activation of delta-opioid receptors affords improvement of functional protection in isolated working rat hearts similar to that conferred by classic ischemic preconditioning. The combination of both pretreatments reduces ischemic cellular damage and further adds to postischemic functional recovery. These changes are reversed by naloxone, an observation providing evidence that ischemic preconditioning involves signaling through opioid receptors.

Animals↗

PubMed2000

Simultaneous treatment of thoracic and infrarenal aortic aneurysm using a combination of conventional surgery and endoluminal stent grafting.

INTRODUCTION: Patients with multiple aortic aneurysms represent a small subgroup with the need for extensive surgical treatment at considerable risk. Endovascular treatment in combination with conventional operation is possible. We demonstrate a case with simultaneous exclusion of aneurysms of the descending thoracic and the infrarenal aorta to outline the technical obligations. CONCLUSION: Simultaneous exclusion of a thoracic and an abdominal aneurysm can be performed successfully by conventional infrarenal aortic replacement with bifurcated dacron prosthesis and endovascular implantation of a thoracic stent-graft within one operation.

Anastomosis, Surgical↗

PubMed2000

[Harvesting the vena saphena magna for aortocoronary bypass operations--is the subcutaneous suture necessary?].

BACKGROUND: The need for stitching the subcutaneous layers after saphenous vein graft harvest for coronary artery bypass is discussed controversially. METHODS: We conducted a prospective study to determine whether subcutaneous stitches reduce the incidence of hematoma, infection and wound dehiscence after saphenous vein graft harvest in patients undergoing coronary artery bypass grafting. Patients were randomized either to group 1 (n = 100, subcutaneous suture) or group 2 (n = 46, without subcutaneous suture). Leg wounds were examined for hematoma, wound dehiscence, necrosis or secretion preoperatively and on day 2 and 5 after surgery. Furthermore, leg circumferences were measured at distinct areas. RESULTS: There were no significant differences in the incidence of wound complications. Especially, leg circumferences and incidence of hematomas (group 1: 36% versus group 2: 39%) as well as the length of hospital stay (group 1: 6.8 days versus group 2: 6.2 days) did not differ significantly. CONCLUSIONS: The subcutaneous suture following saphenectomy is unnecessary. A deterimental effect of an additional subcutaneous suture could not be demonstrated.

Aged↗

PubMed1999

Identification of 9 novel FBN1 mutations in German patients with Marfan syndrome.

We report 9 new mutations in German patients presenting with classical Marfan syndrome. All mutations occur in exons with calcium-binding (cb) epidermal growth factor-like (EGF) domains. Five mutations are missense involving exons 12, 27, 30, 44, and 52 with the resultant substitution of cysteine by phenylalanine (C504F), cysteine by tyrosine (C1129Y), tyrosine by cysteine (Y1261C), cysteine by serine (C1833S), and cysteine by tyrosine (C2142Y), respectively. The other four mutations are single base deletions in exons 39, 43, 48, and 58, at nucleotide A4826, C5311, T6018, and A7291, respectively, each resulting in frameshift with premature termination. Four mutations were detected in sporadic cases and are likely to be de novo.

Adult↗

PubMed1999

The use of gelatin-resorcin-formalin glue in acute aortic dissection type A.

OBJECTIVES: The Gelatin-resorcin-formalin (GRF) glue is widely used in the surgical treatment of dissecting aneurysms. This paper is focused on our experience with the GRF glue in cases, operated for acute aortic dissection type A. METHODS: Between September 1990 and December 1997, 164 patients were operated on for acute aortic dissection type A. In 148 patients GRF was used to reinforce the dissected layers proximal (n = 106) or distal (n = 144) of the grafted aortic segment. An intervention at the aortic valve was necessary in 93 instances. In 111 patients, an open distal anastomosis for replacement of the proximal aortic arch was performed. Thirty-seven additional patients underwent subtotal or total aortic arch replacement. RESULTS: Early postoperative mortality was 26.2% (43/164 patients). Another 16 patients died late postoperatively. Actuarial survival rates are 69.9% at 1 year, 62.5% at 3 years, 59.4% at 5 years and 56.1% at 7 years, post-operatively. Twenty-two reoperations were performed in 20 patients (16.5%). Nine of these patients had developed complications in aortic segments that underwent reconstruction by use of GRF during the primary intervention. Aortic root redissection was found in 7/9 patients intraoperatively, whereas 1/9 patients presented with a rupture near the distal graft to aortic anastomosis. CONCLUSIONS: The introduction of GRF glue has greatly facilitated the reconstruction of dissected aortic wall layers adjacent to the vascular graft. However, the use of the adhesive for aortic root reconstruction in acute aortic dissection type A may bear a significant risk of late postoperative proximal aortic redissection. Complications associated with the GRF glue are likely to be due to the toxic effects of the formalin component. Therefore, care should be taken that the amount of formalin administered to the glue components remains as low as possible.

Acute Disease↗

PubMed1998

[Marfan syndrome: therapy of cardiovascular manifestations].

With optimal clinical management of patients with Marfan syndrome, life expectancy may be improved substantially from 32 years to a nearly normal life span. Cornerstones of clinical management comprise genetic counseling, life-style management, and cardiovascular surveillance, which includes regular aortic imaging and endocarditis prophylaxis. Prophylactic use of beta-blocking agents as well as timing of elective surgery and the choice of the optimal surgical technique are difficult issues that obviously need to be individualized. Juvenile or postoperative patients as well as pregnant patients with Marfan syndrome pose particular problems. This review intends both to facilitate differential decision making based on referenced evidence and to provide guidelines for therapeutic strategies. Finally, a review of the most recent advances to somatic gene therapy is given.

Adolescent↗

PubMed1998

Rupture of the ascending aorta in Ehlers-Danlos syndrome after surgical repair of multiple arteriovenous malformations with the use of cardiopulmonary bypass.

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Adult↗

PubMed1998

ON-X bileaflet valve in aortic position--early experience shows an improved hemodynamic profile.

BACKGROUND: Despite considerable progress during the last decades, mechanical heart valves still have significant disadvantages in performance compared to native valves. To optimize the hemodynamic profile, a new mechanical bileaflet valve (ON-X) was developed and introduced in 1997. It was the aim of this study to assess the feasibility, safety, and the early postoperative hemodynamics with this new valve in vivo. METHODS: We analyzed 19 patients (11 male, 8 female; 63.2 +/- 8.2 years; aortic stenosis: n = 13; aortic incompetence: n = 2; combined aortic lesion: n = 2), undergoing aortic valve replacement with this prosthesis (valve size 19 mm: n = 1; 21 mm: n = 6; 23 mm: n = 8; 25 mm: n = 4; additional CABG: n = 4). In addition to intraoperative pressure gradient measurements, echocardiography was performed early postoperatively and after 3 months, evaluating pressure loss, effective orifice area, and regression of left-ventricular hypertrophy. RESULTS: No major perioperative complications were observed. The echocardiographic evaluation demonstrated a significantly increased effective orifice area and lower transvalvular gradients in all valve sizes compared with literature values for the St. Jude Medical prosthesis. Effective regression of left-ventricular hypertrophy (-23.6%) was observed over the first three months. CONCLUSIONS: These preliminary data confirm the favorable hemodynamic characteristics of the ON-X valve as compared to standard bileaflet designs. Implantation was feasible and safe, and no major postoperative complications such as thrombembolic events were observed.

Aortic Valve↗

PubMed1998

Ischemic preconditioning as an adjunct to crystalloid or blood cardioplegia for myocardial protection in routine coronary surgery.

Experimental preconditioning is commonly regarded as a powerful protective phenomenon in case of subsequent ischemia. However, little is known about the applicability of preconditioning as an adjunct to cardioplegic myocardial protection in routine coronary surgery. For this reason, a prospective clinical study (611995 to 4/1996) was initiated to evaluate normothermic ischemic preconditioning prior to crystalloid or cold blood cardioplegic arrest. Preconditioning was performed in two cycles of 5 min ischemia and 10 min reperfusion. Four groups of 7 patients each were compared regarding release of troponin T, creatine kinase-myocardial isoform (CK-MB), lactate, and total CK in coronary sinus effluents over a 12-hour period. In the absence of perioperative myocardial infarction, there were no significant differences in these ischemic and metabolic parameters. Unexpectedly, the heed of postoperative pharmacological inotropic support was greater after preconditioning. These results may indicate that ischemic preconditioning as an adjunct to cardioplegic arrest may be associated with impairment of left-ventricular contractility, thus even exerting potentially detrimental functional effects. Overall, the proven beneficial effects of experimental preconditioning seem not to be directly transferable into the clinical settings.

Aged↗

PubMed1998

[Ischemic preconditioning of the heart can be simulated by pharmacologic hibernation enkephalins].

The protective effects of ischemic preconditioning on the myocardium can be abolished by pretreatment with opioid receptor antagonists. We investigated, if--vice versa--the protective effect of preconditioning may be induced by systemic pretreatment with the delta-opioid receptor agonist D-Ala2-DLeu5-enkephalin (DADLE). DADLE is known to be very similar to the trigger substance that induces natural hibernation. Isolated working rat hearts of male Wistar rats (n = 32) were subjected to 45 minutes of global hypothermic ischemia at 30 degrees C followed by 25 minutes of normothermic reperfusion. Hearts from rats injected with 1 mg/kg DADLE intravenously 1 hour before isolated perfusion were either preconditioned by one cycle of 5 minutes of normothermic ischemia followed by 5 minutes of normothermic reperfusion or hearts were not preconditioned during preischemic perfusion. Untreated preconditioned and non-preconditioned hearts served as controls. Ischemic preconditioning alone and DADLE alone improved the recovery of aortic flow and reduced the creatine kinase leakage significantly during postischemic reperfusion. Over and above that, pretreatment with DADLE prior to ischemic preconditioning significantly further enhanced functional recovery and reduced the creatine kinase leakage, when compared to DADLE alone and preconditioning alone. Therefore we conclude, that DADLE attenuates ischemic injury in isolated rat hearts and enhances the protective effects of ischemic preconditioning. The data suggest that ischemic preconditioning and DADLE act via a similar pathway.

Animals↗

PubMed1998

[Altitude exposure induces hypoxic preconditioning of the heart].

Under in vitro conditions, the resistance to ischemia may be improved by hypoxic preconditioning. This study was designed to test the hypothesis, that hypoxic preconditioning can also be induced in vivo by exposure of an intact animal to simulated high altitude. Male Wister rats (n = 48) were exposed for 60 minutes to simulated high altitude at 3000 m or 5000 m above sea level in a hypobaric chamber. 30, 150 or 300 min following exposure, hearts were excised and perfused aerobically in the working heart model prior to 45 minutes of global ischemia at 30 degrees C and subsequent normothermic reperfusion. For control, hearts of unexposed rats were either preconditioned by one cycle of 5 minutes of normothermic ischemia and reperfusion prior to subsequent ischemia or (n = 8) or not (n = 8). Postischemic measurements included functional parameters such as aortic flow, maximum developed left ventricular pressure, creatine kinase leakage from collected samples of the coronary effluent and the morphometric assessment of the area of myocardium at risk. When compared to non-preconditioning, ischemic preconditioning significantly improved the recovery of aortic flow, left ventricular systolic pressure and reduced the postischemic creatine kinase leakage. Likewise, exposure to a simulated high altitude at 3000 m above sea level significantly improved the recovery of aortic flow and reduced creatinkinase leakage when the time interval between exposure to simulated high altitude and perfusion was set to 150 minutes. Further increase in hypoxic stress (5000 m above sea level) or the reduction of this time interval to 30 minutes reduced postischemic recovery of hearts. The exposure of an intact organism to simulated high altitude can improve the resistance of the heart to ischemia by hypoxic preconditioning. The induction of this beneficial effect depends on the level of hypoxic stress and the time interval between preconditioning and subsequent ischemia.

Altitude↗