Biomedical subjects
Publications and source records attributed to Johannes M Albes.
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The first case of a fracture of a semi-rigid annuloplasty device is reported. A 56-year-old man presented with recurrence of severe mitral and tricuspid regurgitation 10 months after proper implantation of a Colvin-Galloway Future band (Medtronic Inc, Minneapolis, MN). During redo surgery we made the unexpected finding that its metal skeleton was fractured near the posterior segment. A tear in the anterior mitral leaflet was also found. It is speculated that the device fracture may have put additional strain on the native annulus.
To effectively perform an anastomosis on a coronary artery under beating heart conditions, the anastomotic site must be cleared of blood to allow visualization for accurate suturing. We describe a simple, cost effective, on-site assembled blower-mister system.
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OBJECTIVE: Adhesives are useful supplements to seal distal coronary anastomoses, particularly in patients who receive less-invasive coupling techniques. Information regarding long-term structural effects after application, however, is limited. The purpose of this large animal study was to examine the effects of 3 different commercially available surgical adhesives. METHODS: Twelve end-to-side anastomoses were created between the left internal thoracic artery and the left anterior descending coronary artery in a porcine beating heart model. Three different adhesives were applied externally and circumferentially to the anastomosis site. In group I (n = 4) gelatin-resorcinol-formaldehyde glue (Cardial, Technopole, Sainte-Etienne, France), in group II (n = 4) n-butyl-2-cyanoacrylate glue, and in group III (n = 4) albumin-glutaraldehyde glue were used. All anastomoses were examined intraoperatively by flow measurement. After 3 months the anastomoses were reassessed for patency and the vessels were evaluated histologically. RESULTS: By means of 4 stay sutures and subsequent glue application, anastomoses could be created successfully on the first attempt in all animals. Perioperative flow through the left internal thoracic artery was similar in all groups. In 4 animals an additional suture was placed to control bleeding. After 3 months, the patency rate was 83.3% (10/12). In group I all anastomoses were patent whereas in both groups II and III one anastomosis was occluded. None of the adhesives caused impaired vessel wall healing but they did demonstrate moderate-to-dense adhesions to the surrounding tissue. On histologic examination, gelantin-resorcinol-formaldehyde glue exhibited minimal tissue reaction (foreign-body granuloma) whereas n-butyl-2-cyanoacrylate glue showed moderate reaction. In contrast, albumin-glutaraldehyde glue caused severe inflammatory reaction with extensive fibroblastic proliferation. CONCLUSION: Construction of an end-to-side internal thoracic artery-coronary artery sleeve anastomosis using adhesives was feasible in the pig. Among the tissue adhesives used in this study, gelantin-resorcinol-formaldehyde glue appeared to be superior to cyanoacrylate and albumin-glutaraldehyde glue. The latter one, however, caused severe adverse histologic effects and thus cannot be recommended for bonding coronary anastomoses.
OBJECTIVE: Biological valves exhibit characteristic curves (CC) regarding transvalvular gradient, resistance, and effective orifice area when correlated with a physiological cardiac output range (CO). The slope of the curve of transvalvular resistance over a typical CO range characterizes the clinical performance of the valve. These information may support an individualized decision towards the most adequate valve type. METHODS: In an extracorporeal mock circuit two types of stented biological aortic valves (constructed pericardial valves, Edwards Perimount: EP; porcine cusp valves, Medtronic Mosaic: MM) of 21, 23, and 25 mm were investigated. Mean transvalvular gradient was measured over a range of 1.9 to 7.2l/min CO at a simulated heart rate of 70 beats/min. Transvalvular resistance was calculated and presented as characteristic curves in a log-log-plot against cardiac output. RESULTS: EP valves of all sizes demonstrated low slopes (resistance range; slope: 21 mm: 53-79 dynes s cm(-5); 0.29; 23 mm: 44-56 dynes s cm(-5); 0.12; 25 mm: 38-45 dynes s cm(-5); 0.12) while MM valves exhibited steep slopes (resistance range; slope: 21 mm: 46-169 dynes s cm(-5); 0.97; 23 mm: 36- -146 dynes s cm(-5); 0.95; 25 mm: 27-64 dynes s cm(-5); 0.68). CONCLUSIONS: While constructed pericardial valves demonstrate sufficient hemodynamic performance especially in the higher CO range porcine cusp valves exhibited minor resistance in the lower CO range. Patients who exercise regularly may therefore profit from a pericardial valve while patients with a small body surface area and little exercise who therefore remain in the lower CO range may be adequately treated with a porcine cusp valve.
Restitution strategies of the insufficient aortic valve belong to the clinical armamentarium. To date, the accumulated body of evidence comprises 126 articles dealing with restitution strategies on the insufficient aortic valve with concomitant aortic surgery. In a cumulative analysis an almost identical number of reimplantation (506) and remodeling (489) procedures were found in the literature, whereas 357 patients underwent aortic valve resuspension. The cumulative results tend to favor the reimplantation technique in terms of longevity of the reconstruction, particularly in congenital degenerative disorders of the aortic wall, whereas remodeling appears to exhibit a more physiologic behavior of the reconstructed valve and re-suspension serves as a simplified approach particularly in acute type A dissection. Although restitution of the native aortic valve has its place in current treatment options, the accumulated worldwide numbers indicate that it is not yet routinely implemented in the vast majority of cardiac institutions.
OBJECTIVE: Closed circuit extracorporeal circulation (CCECC) has been developed to reduce deleterious effects of standard cardiopulmonary bypass (CPB). This study compares the effects of CCECC (CORx system), CPB, and off-pump coronary artery bypass grafting (OPCAB) on red blood cell damage, coagulation activation, fibrinolysis and cytokine expression. METHODS: Thirty patients underwent coronary artery bypass grafting (CABG). Twenty of them were randomized into two groups: CCECC (n = 10), CPB (n = 10). While not randomized, OPCAB (n = 10) served as a separate reference group. CCECC and CPB patients received cardioplegic arrest. Interleukin 6 (IL-6), free hemoglobin (fHb), von Willebrand factor activity (vWf), thrombin-antithrombin-III-complex (TATc), prothrombin fragment 1.2 (F 1+2) and plasmin-antiplasmin complex (PAPc) were assessed preoperatively, perioperatively and 24 h postoperatively. RESULTS: CCECC showed significantly lower red blood cell damage than CPB (fHb: CCECC, 7.1+/- 5.7 micromol/l; CPB, 16.8+/-11.4 micromol/l; P = 0.025; OPCAB, 3.4+/-1.1 micromol/l). Perioperatively, CCECC exhibited significantly lower activation of coagulation and fibrinolysis than CPB, but did not differ from OPCAB (vWf: CCECC, 133+/-52%; CPB, 241+/-128%; P = 0.052; OPCAB, 153+/-58%; TATc: CCECC, 4.7+/-0.9 ng/ml; CPB, 31.1+/-15.8 ng/ml; P < 0.001; OPCAB, 2.4+/-0.6 ng/ml; PAPc: CCECC, 214+/-30 ng/ml; CPB, 897+/-367 ng/ml; P < 0.001; OPCAB, 253+/-98 ng/ml). In contrast, fibrinolysis markers and IL-6 were markedly increased in CCECC postoperatively (PAPc: CCECC, 458+/-98 ng/ml; CPB, 159+/-128 ng/ml; P < 0.001; OPCAB, 262+/-174 ng/ml; IL-6: CCECC, 123.4+/-49.8 pg/dl; CPB, 18.8+/-13.1 pg/dl; P < 0.001; OPCAB, 31.6+/-26.2 pg/dl). CONCLUSIONS: CCECC for CABG is associated with a significant reduction of red blood cell damage and activation of coagulation cascades similar to OPCAB when compared with conventional CPB while a delayed fibrinolytic and inflammatory activity was observed. These findings require further investigation to verify the promising concept of CCECC.
BACKGROUND AND AIM OF THE STUDY: Positioning of a mechanical prosthesis outside the native annulus facilitates mitral valve replacement, especially when the annulus is small and calcified, and preservation of the posterior leaflet (PML) is desired. Herein is described the authors' initial experience with a new mechanical bileaflet prosthesis comprising a sheltered leaflet housing and a novel, modified asymmetrical sewing ring for an 'atrialized' implantation technique. METHODS: Forty-seven patients (24 males, 23 females; mean age 65.8 +/- 10.9 years) were operated on for isolated mitral regurgitation or combined stenosis and insufficiency. Ten of the patients underwent valve replacement due to active endocarditis. Preoperative cardiac insufficiency was reflected by a mean NYHA class of 2.6 +/- 0.7. The On-X Conform-X bileaflet mitral valve prosthesis (25/33 mm) was implanted in either an epiannular (43 patients) or intra-annular (four patients) fashion, and the PML and its chordae tendineae were preservable in 33 patients (70.2%). All patients were monitored intraoperatively by transesophageal echocardiography (TEE) and post-operatively by transthoracic echocardiography (TTE). RESULTS: TEE and TTE exhibited excellent function with low mean transvalvular gradients early after surgery (4.9 +/- 2.7 mmHg) and after three months (4.8 +/- 1.4 mmHg). Paravalvular leakage was not detected. Initial postoperative left ventricular (LV) function was almost identical to preoperative findings (ejection fraction: preop. 55.1 +/- 13.7%, early postop. 53.7 +/- 13.6%) and improved slightly after three months (60.1 +/- 6.4%). Clinically significant hemolysis was not apparent (LDH at postoperative day 7: 5.3 +/- 0.8 micromol/l x s). Two patients died from multiorgan failure (4.2%) and four are currently in a reduced condition requiring long-term hospitalization (morbidity 8.5%). After three months all other patients were in an excellent clinical state (mean NYHA class 1.5 +/- 0.6) and being followed up as outpatients. CONCLUSION: Current designs of mechanical bileaflet valves require redundant space in the LV cavity for undisturbed leaflet movement. A small annulus, marked fibrosis and calcification of the valvular apparatus can lead to an impedance of prosthetic leaflet motion. Consequently, the native leaflets are often removed. The cylindrical housing of the On-X valve shelters almost the entire motion of the leaflets, allowing an undisturbed function and improved transvalvular flow pattern. The newly developed asymmetrical sewing ring facilitates anchoring of the ring in an 'atrialized' fashion, while the flexibility of the cuff adapts to all native ring diameters larger than 25 mm.
BACKGROUND: Temporary intraluminal shunts (TILS) are routinely used in off-pump revascularization to facilitate the anastomosis while maintaining myocardial blood supply. Whereas tourniquet-occlusion can cause vessel wall trauma, potentially adverse chronic effects of TILS on the coronary intima have not been evaluated yet. This chronic large animal study investigated ultrastructural effects of TILS on the vessel wall. METHODS: Four groups of acute and chronic pigs with either tourniquet-occlusion (TOUR) or TILS (40 kg; acute, n = 12; chronic, n = 20) were analyzed. Animals underwent median sternotomy, heparin (150 U/kg) administration, and left anterior descending coronary artery exposure. In groups with TOUR the left anterior descending coronary artery was temporarily occluded (10 minutes) with a tourniquet. In groups with TILS a silicone shunt (1.5 mm diameter, 12 mm length) was placed in the left anterior descending coronary artery more than 10 minutes and then removed, and the insertion was repaired. Thirty minutes after reperfusion all acute animals were sacrificed whereas chronic animals were extubated, maintained for 3 months, and then sacrificed. The left anterior descending coronary artery regions of occlusion or placement of the TILS silicone bulbs were examined histopathologically by scanning and transmission electron microscopy by a blinded pathologist. RESULTS: In both acute and chronic investigations animals in the TILS group exhibited significantly less morphologic damage than animals in the TOUR group. In the acute phase significantly more loss of cell junction (p = 0.037), loss of endothelium (p = 0.032), and intimal edema (p = 0.037) in the TOUR group than in the TILS group was observed. Three months later, characteristic features with a changed pattern were detected: vacuolization of the cell (p = 0.03), loss of cell junction (p = 0.042), and removal of basal membrane (p = 0.046) as well as extensive loss of endothelium (p = 0.003) in the TOUR group compared with the TILS group. CONCLUSIONS: Intimal lesions occur with both maneuvers early and late. However, animals in the TOUR group exhibited injuries significantly more often and more severely. Therefore, acute and chronic intimal integrity of the coronary vessel may be better preserved using TILS and may thus have a positive impact on the extent of de novo stenosis and long-term prognosis of the revascularized region.
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Reconstruction of the aortic valve and replacement of the ascending aorta instead of use of a composite graft is the preferred method in patients, who demonstrate an ascending aneurysm accompanied by aortic root enlargement and aortic valve insufficiency with morphologically intact cusps. Two techniques inaugurated by David and Yacoub have gained widespread acceptance. However, both approaches are technically demanding. We present a simplified alternative technique for aortic valve reconstruction by means of a reduction plasty of the aortic root without the necessity of transection maneuvers.
BACKGROUND: Mechanical bileaflet valves with enhanced inner diameter may offer superior hemodynamic properties in patients with a small aortic annulus. The aim of this clinical study was to compare these valves with standard bileaflet prostheses in vivo. METHODS: Mechanical aortic valve replacement for combined stenosis and regurgitation was performed in 47 patients with standard CarboMedics prostheses (CM: 21 mm, 23 mm, 25 mm) and two types of diameter enhanced St. Jude Medical prostheses (SJM-AHPJ: 21 mm, 23 mm, 25 mm; SJM-Regent: 21 mm, 23 mm). Transvalvular mean gradients (TVG) were assessed intraoperatively by means of transesophageal echocardiography (TVG(TEE)) and simultaneous direct pressure monitoring of the left ventricle and the ascending aorta (TVG(CATH)), as well as early (3 months) and late (9 months) postoperatively by means of transthoracic echocardiography (TVG(TTE)). Left ventricular muscle mass was assessed preoperatively, early, and late postoperatively to evaluate remodeling capacity. RESULTS: In all valve types and sizes, both TVG assessments exhibited consistent findings. Small-sized conventional valves of 21 mm showed a marked initial TVG. In contrast, both valve types with enhanced inner diameter exhibited significantly lower TVG comparable with those achieved with larger valves (TVG(CATH) CM 21 mm, 15.6 +/- 3.9 mm Hg; SJM-AHPJ 21 mm, 11.9 +/- 1.6 mm Hg; SJM-Regent 21 mm, 9.9 +/- 1.1 mm Hg; CM 23 mm, 7.8 +/- 0.8 mm Hg; SJM-AHPJ 23 mm, 7.7 +/- 1.4 mm Hg; SJM-Regent 23 mm, 9.5 +/- 1.8 mm Hg). During the postoperative course TVG remained constant in all valve types and sizes. Left ventricular muscle mass, however, diminished markedly in all valves without exhibiting significant differences between size matched valve types. CONCLUSIONS: In patients with a small aortic annulus, who require a 21-mm valve, diameter-enhanced prostheses provide lower transvalvular gradients than conventional valves. However, in the intermediate clinical course, appropriate left ventricular remodeling occurred in all patients independent of the size and the type of the valve.
OBJECTIVE: Optimal preservation of postischemic graft function is essential in lung transplantation. Antegrade flush perfusion with modified Euro-Collins solution represents the standard technique worldwide. However, growing evidence suggests the superiority of extracellular-type Perfadex solution (Vitrolife AB, Gothenburg, Germany) over Euro-Collins solution. During ischemia and reperfusion, endogenous pulmonary nitric oxide synthesis is decreased, and therefore therapeutic stimulation of the nitric oxide pathway might be beneficial in ameliorating ischemia-reperfusion damage. However, research mainly focuses on nitric oxide supplementation of intracellular solutions, and no studies exist in which the effect of nitroglycerin on Perfadex preservation quality is evaluated. METHODS: Eight rat lungs each were preserved with Perfadex solution with or without nitroglycerin (0.1 mg/mL) and compared with low-potassium Euro-Collins solution. Postischemic lungs were reventilated and reperfused, and oxygenation capacity, pulmonary vascular resistance, and peak inspiratory pressures were monitored continuously. Stereological analysis was used for evaluation of pulmonary edema and assessment of the vasculature. Statistics were performed by using different analysis of variance models. RESULTS: The oxygenation capacity of the Perfadex-preserved groups was higher compared with that of the low-potassium Euro-Collins solution group (P <.03). By using nitroglycerin, flush-perfusion time was reduced, and Perfadex solution with nitroglycerin-protected lungs showed superior oxygenation capacity compared with that seen in Perfadex solution-protected organs (P <.01). Furthermore, pulmonary vascular resistance and peak inspiratory pressures were improved in the nitroglycerin group (P <.01). Stereology revealed comparable intrapulmonary edema between groups and a trend toward less vasoconstricted vasculature in Perfadex with nitroglycerin-protected lungs. CONCLUSIONS: Perfadex solution provides superior lung preservation in terms of postischemic oxygenation capacity than Euro-Collins solution. Supplementation of the nitric oxide pathway by nitroglycerin further enhances functional outcome of Perfadex-preserved organs and might be an easily applicable tool in clinical lung transplantation.
OBJECTIVE: Conventional extracorporeal circulation results in an activation of coagulation cascades. Coating of extracorporeal circulation tubes as well as avoidance of shed blood recirculation have been shown to reduce these phenomena. We evaluated a new shed blood separation system (AVANT D 970) utilizing a coated cardiopulmonary bypass tube system (PHISIO). METHODS: Forty patients (62 +/- 10 years) underwent isolated coronary revascularization. Four groups (n = 10/group) were defined: no extracorporeal circulation, conventional uncoated extracorporeal circulation, uncoated extracorporeal circulation with shed blood separation, and coated extracorporeal circulation with shed blood separation. Thrombin-antithrombin complex and free Hb were analyzed and statistically compared. RESULTS: Conventional extracorporeal circulation exhibited the highest intraoperative activation of coagulation (thrombin-antithrombin complex: extracorporeal circulation, 31.1 +/- 15.8 microg/L; uncoated extracorporeal circulation with shed blood separation, 15.3 +/- 7.8 microg/L; coated extracorporeal circulation with shed blood separation, 8.1 +/- 4.8 microg/L; no extracorporeal circulation, 2.4 +/- 0.6 microg/L; P <.05 extracorporeal circulation vs all others) and red blood cell damage (free Hb: extracorporeal circulation, 16.8 +/- 11.4 micromol/L; uncoated extracorporeal circulation with shed blood separation, 10.3 +/- 3.5 micromol/L; coated extracorporeal circulation with shed blood separation, 6.8 +/- 2.9 micromol/L; no extracorporeal circulation, 3.4 +/- 1.1 micromol/L; P <.05 extracorporeal circulation vs no extracorporeal circulation, coated extracorporeal circulation with shed blood separation). Coated extracorporeal circulation with shed blood separation showed only slight activation and cell trauma, which did not differ significantly from no extracorporeal circulation. CONCLUSIONS: Combination of coating and avoidance of shed blood recirculation maintained physiological coagulation levels and markedly reduced red blood cell trauma in extracorporeal circulation procedures. These combined modalities may therefore offer an alternative for off-pump procedures in patients with contraindications for conventional extracorporeal circulation.
OBJECTIVES: Severe sclerosis of the native aortic annulus can result in a tilted implantation position of mechanical prostheses. In this study, the effects of tilting and rotation on the hemodynamic performance of standard bileaflet valves were assessed in an extracorporeal mock circulatory system. METHODS: A pulsatile mock circulation driven by a Berlin Heart system was developed. Main physiological components of the human circulation were mimicked. SJM-AHPJ prostheses (21, 23, 25 mm) were mounted in an artificial aortic root containing physiologically oriented coronary ostia. All experiments were performed under constant conditions (stroke volume 60 ml, heart rate 70 bpm, systolic pressure 130 mmHg). Hydrostatic pressures were measured via fluid-filled catheters, transvalvular flow by ultrasonic probes. Data were digitally recorded at 50 Hz. Multiple pressure, volume, energy, and dimension parameters were derived off-line. Each valve was tested in a 0 degrees (untilted) versus 20 degrees (tilted) position at three axial rotation angles (0 degrees, 45 degrees, 90 degrees ). Tilting was performed independent of rotation by elevation of the prosthesis in the non-coronary sinus. RESULTS: In all valves and all rotation angles, tilting resulted in a size-dependent significant increase of mean pressure gradient (range, 28-35% [21 mm valve], 59-96% [23 mm valve], 124-220% [25 mm valve]), valvular resistance (39-51, 84-121, 177-332%), regurgitation volume (84-148, 32-131, 93-118%), and systolic energy loss (113-146, 30-132, 69-213%), as well as a decrease of total stroke volume (2-5, 0-11, 3-10%), effective stroke volume (6-11, 9-14, 14-22%), cardiac output (6-11, 8-14, 13-22%), and effective opening area (16-24, 32-37, 47-57%). The strongest impairment of hemodynamic performance was seen at 90 degrees rotation with reference to total and effective stroke volume, cardiac output, mean pressure gradient, and regurgitation fraction. CONCLUSIONS: Tilting of bileaflet valves resulted in a significant impairment of systolic and diastolic hemodynamics. Superiority of larger valves diminished in the tilted position. The strongest tilting effect was seen at 90 degrees rotation. Such a position should therefore be avoided or surgically corrected by rotating the valve.