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Biomedical subjects

M Doss

Publications and source records attributed to M Doss.

At least 19 recordsLinked to original sources
PubMed2006

Decalcification of the mitral annulus: surgical experience in 81 patients.

OBJECTIVE: Mitral valve surgery in the presence of extensive calcification of the mitral annulus is a technical challenge and increases perioperative risk. This study reviews our experience with decalcification of the mitral annulus in patients undergoing mitral valve reconstruction or replacement. METHODS: From 1995 to 2003, 81 patients (mean age 64 +/- 13 years, 30 male, 51 female) with extensive calcification of the mitral annulus underwent mitral valve repair (n = 42) or replacement (biological n = 20, mechanical n = 19). The mean follow-up was 24 months. Patients presented with a mean EuroSCORE of 7. Concomitant surgical procedures were performed in 62 %. Patient outcomes were retrospectively assessed. RESULTS: Perioperative survival was 97.5 % (n = 79) and hospital survival was 91.3 % (n = 74). Two-year survival was 88.9 %. Eight patients needed reexploration due to bleeding and five patients required prolonged mechanical ventilation. No perioperative stroke was observed. Freedom from reoperation was 90.2 % (n = 73). Early reoperation for recurrent incompetence was necessary in 3 patients and late reoperation in 5 patients. CONCLUSIONS: Despite the elevated perioperative risk and the high risk of reoperation with this procedure, decalcification of the annulus and repair/replacement of the mitral valve could be performed with good clinical results.

Adolescent↗
PubMed2006

Behavior of gaseous microemboli in extracorporeal circuits: air versus CO2.

BACKGROUND: Open heart surgery is associated with serious risk of cerebral and peripheral organ dysfunction, attributed in part to air microbubbles generated in or not eliminated from the extracorporeal circuit (ECC). Venous air leakage leads to increased arterial bubble load. CO2 replacing air in cardiac chambers show faster resorption times, reducing possible cerebral or peripheral organ damage after heart valve interventions. In two models of ECC the effect of air entering closed circuits was demonstrated and compared to the effect of CO2 entry. METHODS: Fragmentation and dissolution of gas (0.5 mL) was evaluated in an in vitro model of ECC, using ultrasonic bubble detection. Air leakage (10 mL) in the venous line of the ECC was simulated and compared to the effect of the same quantity of CO2 entering the circuit. Both models used whole blood priming and physiological conditions, verified with blood gas analyses. RESULTS: Fragmentation and dissolution of gas bubbles injected into a closed ECC could be demonstrated, complete resorption of CO2 bubbles was observed earlier than complete resorption of room air (5.0+/-0.6 vs. 14.4+/-5.9 min, p=0.0009). CO2 entering the venous line lead to 40% less arterial bubble load as compared to the same amount of room air entering the circuit (2099+/-991 vs. 3555+/-632, p=0.005). CONCLUSIONS: Current ECC systems fail to eliminate gas entering the circuit, leading rather to microbubble dispersion. CO2 is much faster resorbed within the circuit than room air. In open heart surgery as valvular operations, CO2 insufflation into the operative field is protective, as we have demonstrated in our models.

Air↗
PubMed2004

Improved cerebral protection through replacement of residual intracavital air by carbon dioxide: a porcine model using diffusion-weighted magnetic resonance imaging.

BACKGROUND: Major risk of central or peripheral organ damage is attributed to air embolism from incompletely de-aired cardiac chambers after cardiac operations. Replacement of air by carbon dioxide insufflation into the thoracic cavity is widely used. Diffusion-weighted magnetic resonance imaging of the brain detects ischemia within minutes after onset. The reversibility of ischemia in cerebral tissue after massive gaseous emboli has not yet been described. METHODS: After selective catheterization of a common carotid artery in 15 pigs, boli of 1 mL/kg body weight of air (n = 5) or carbon dioxide (n = 5, "low dose") were applied. Five pigs received 2 mL/kg body weight of carbon dioxide ("high dose"). Diffusion-weighted magnetic resonance imaging of the brain was performed 2, 5, 10, 15, and 25 minutes after embolization. RESULTS: All animals of the "air" group showed important circulatory reactions leading to death of 2 animals. In the whole group, diffusion-weighted magnetic resonance imaging revealed irreversible hyperintense signals in both hemispheres. In the low-dose group, no change in signal intensity was observed in 2 pigs, and 3 others showed reversible changes in signal intensity, without important circulatory reactions. In 3 animals of the high-dose group, hyperintense signals were reversible, but 2 others presented with bilateral, irreversible signals in diffusion-weighted magnetic resonance imaging, accompanied by minor circulatory reactions. CONCLUSION: In contrast to the dramatic effect of air emboli, identical quantities of carbon dioxide injected into cerebral arteries of the pigs were not associated with major clinical symptoms. The early reversibility of ischemic reactions visualized in diffusion-weighted magnetic resonance imaging encourages the use of carbon dioxide insufflation as a protective method in cardiac surgery.

Animals↗
PubMed2004

[Thoracic aortic stenting: indications and results].

AIM: Determination of the conditions for good acute and long term results of interventional therapy of lesions of the thoracic aorta using stent-grafts. PATIENTS, MATERIAL AND METHODS: 51 patients with aneurysm of the thoracic aorta (type B dissections) covered rupture and aortobronchial fistula were evaluated. All cases were discussed in an interdisciplinary conference consisting of thoracic surgeon and interventional radiologist. Primarily, 20 patients were operated and 31 were treated by intervention. For all a multidetector row CT angiography was ordered prior to the discussion. All procedures were performed in a DSA suite under general anaesthesia. In 29 patients Talent LPS trade mark tube grafts and in four patients an Excluder trade mark graft was implanted. RESULTS: 29 patients had an aneurysm of the thoracic aorta, 21 a type B dissection, 19 a perforation and one patient had an aortobronchial fistula. The follow up was 13.4 months. In 29 patients the stent-graft implantation was successful, in 2 patients stent-graft delivery failed due to severe calcification and kincking of both common iliac arteries. One patient had an iliacal dissection after stent-graft delivery which was treated successfully by surgery. In two patients CT angiographic control detected endoleaks, which were treated with a second stent-graft placement. One patient with an acute perforation of the descending aorta died due to cardiac failure prior to stent-graft implantation. Any neurological complication did not occur. CONCLUSION: Percutaneous treatment of lesions of the descending thoracic aorta using stent-grafts is a safe and feasible alternative treatment to surgical repair. Prior to the a multidetector row CT angiography is necessary for exact planning of the endo-luminal treatment.

Aged↗
PubMed2003

Do surface modifying additives (SMA) influence blood loss and thrombogenicity in conventional cardiopulmonary bypass for coronary artery bypass grafting?

Cardiopulmonary bypass (CPB) leads to activation of the coagulation and fibrinolytic cascades, partially associated with foreign surface contact. Hemorrhage and the need for blood products is associated with rising cost and increased risk of infection. Treatment with surface modifying additives (SMA) has been shown to reduce thrombogenicity and improve biocompatibility. 76 elective CABG-patients were randomly assigned to surface modifying additives (group I, n=39) or untreated circuits that were otherwise identical (group II, n=37). Measurements of coagulation activity and fibrinolysis, platelet count and function were made. The postoperative blood loss and blood product replacement was also assessed. Thrombin formation measured by prothrombin fragments 1+2 (5.7+/-0.4 nmol/l vs. 5.6+/-0.4 nmol/l), fibrinolytic activity measured by plasmin-antiplasmin complex (1752.6+/-216.8 microg/l vs.1180.0+/-74.8 microg/l) and the postoperative platelet count and function did not differ significantly between the two groups. Blood loss and transfusion requirements were slightly lower in the SMA group. The treatment of extracorporeal surfaces with surface modifying additives does not appear to reduce coagulation disorders and bleeding after conventional CPB.

Aged↗
PubMed2003

Performance of stentless versus stented aortic valve bioprostheses in the elderly patient: a prospective randomized trial.

OBJECTIVES: Although stentless aortic bioprostheses are believed to offer improved outcomes, benefits remain unsubstantiated. The aim of our study was to compare stentless with stented bioprostheses, with regard to postoperative changes in left ventricular mass and hemodynamic performance, in the elderly patient. METHODS: Forty patients with aortic stenoses, over the age of 75 years, were randomized to receive either the stented Perimount (n=20) or the stentless Prima Plus (n=20) bioprosthesis. Left ventricular mass regression, effective orifice area, ejection fraction and mean gradients were evaluated at discharge, 6 months and 1 year after surgery. RESULTS: Overall a significant decrease in left ventricular mass was found 1 year postoperatively. However, there was no significant difference in the rate of left ventricular mass regression between the groups. Furthermore, 1 year postoperatively, the hemodynamic performance of the valves and the change in the ejection fraction did not differ between the groups. CONCLUSIONS: Our study shows that in a randomized cohort of elderly patients with aortic stenosis, we were not able to detect significant differences, with regard to hemodynamic performance and regression of left ventricular mass, between the stentless and stented valve groups. To our surprise, previously reported findings of non-randomized trials that showed faster and more complete regression of left ventricular mass and hemodynamic benefits of stentless valves were not reproducible.

Aged↗
PubMed2003

Five-year follow-up after long plaque-bridging coronary arteriotomy for diffuse coronary artery disease.

UNLABELLED: Long arteriotomy bridging a stenotic plaque or segment may improve runoff in diffuse coronary artery disease. However, patency might be impaired due to vascular wall pathology. OBJECTIVE: To determine the patency rates of plaque-bridging arteriotomy compared to conventional coronary artery bypass grafting. METHODS: Between May 1995 and December 1998, 104 patients with a mean age of 65 +/- 7 years received a long arteriotomy extending over a heavily plaqued area in an effort to treat their diffuse coronary artery disease. The length of the arteriotomy ranged from 14 mm to 40 mm. We retrospectively analyzed the intra-individual bypass graft patency rates by multidetector-computed tomography or coronary angiography. RESULTS: The mean follow-up was 5 years. There were 5 (4.8 %) early and 10 (9.6 %) late deaths, three non-cardiovascular. Graft patency for internal thoracic artery (ITA) to left anterior descending artery (LAD) (plaque-bridging) was 94.8 %, for saphenous vein graft (SVG) to circumflex artery (CX) (plaque-bridging) 67 %, and SVG to right coronary artery (RCA) (plaque-bridging) 79.5 %. Graft patency for ITA to LAD (conventional) was 94.9 %, for SVG to CX (conventional) 72.4 %, and SVG to RCA (conventional) 75 %. Freedom from angina was 82.8 % (n = 58/70), freedom from myocardial infarction was 95.7 % (n = 67/70), freedom from reintervention was 91.4 % (n = 64/70) and freedom from reoperation was 100 % (n = 70/70). CONCLUSION: Diffuse coronary artery disease can be treated by extending the arteriotomy over the plaques, with graft patency rates comparable to bypass grafts onto less diseased segments.

Aged↗
PubMed2002

A molecular, enzymatic and clinical study in a family with hereditary coproporphyria.

A 30-year-old woman suffered from acute crises with abdominal, neurological and psychiatric complaints. Urinary haem precursors and faecal porphyrins were excessively elevated compared to the upper level of the normal range. Urinary coproporphyrin isomer III was increased and faecal coproporphyrin isomers I and III showed a complete inversion of the normal ratio. Thus, hereditary coproporphyria was diagnosed in this woman. The father, one brother and a sister were shown to be gene carriers of hereditary coproporphyria by their urinary and faecal excretory constellations. The excretory patterns of the mother and a second brother were normal. Coproporphyrinogen oxidase activity was decreased to 49% and 58%, in the patient and her father, respectively. The mother's enzyme activity was normal (98%). Coproporphyrinogen oxidase concentration was enhanced 1.8-fold and 2.7-fold in the patient and her father, respectively. Mutation analysis revealed the insertion of an adenine at position 857 in exon 4 of the coproporphyrinogen oxidase gene. The gene defect was confirmed by denaturing gradient gel electrophoresis in the patient and her father. The patient was treated by intravenous interval therapy with haem arginate for 10 months, with good clinical and metabolic response.

Adult↗
PubMed2002

[Successful reoperation of a ruptured aortic arch aneurysm in Takayasu arteritis].

Successful reoperation of a ruptured aortic arch aneurysm in a patient with Takayasu's disease. Takayasu's disease is an inflammatory arteriopathy that often progresses to stenosis or aneurysms of the large arteries of the aortic arch. In this connection aneurysms of the ascending aorta are rare. We report the case of a 33 years old female with a ruptured aneurysm of the ascending aorta complicated by a former operation of a truncobicarotidal bypass and severe sclerosis. After ascending aorta and aortic arch replacement was performed in deep hypothermia circulatory arrest we could discharge the patient in good condition on the 11. postoperative day.

Adult↗
PubMed2002

Sutured coronary artery grafting utilizing the Heartflo anastomosis device--first clinical experiences.

BACKGROUND: The Heartflo device was developed to facilitate consistency in distal coronary anastomosis quality. The device automates the suturing process during the anastomosis procedure via simultaneous delivery of ten standard 7-0 polypropylene sutures through the graft and the coronary vessel wall. METHODS: In 30 elective coronary artery bypass patients, one distal anastomosis was intentionally performed with the anastomosis device. Device success was stated if a patent anastomosis with a minimal flow of 50 ml/min resulted, additional stitches were counted if bleeding occurred. RESULTS: 4 cases of device failure occurred in the first 5 patients. The subsequent patients were operated without any mechanical problems. In 16 patients (53 %), a patent anastomosis with a mean flow of 75 +/- 6 ml/min using 1.7 +/- 0.3 additional stitches was achieved. Anastomoses were completed in 19.0 +/- 0.7 min; postoperative course was uneventful in all patients. CONCLUSIONS: We have shown that coronary anastomoses are feasible using the Heartflo device, representing a promising step on the way to automated coronary anastomoses. Its application is still limited by the size and tissue quality of the target vessel and difficult suture management during the anastomosis procedure.

Aged↗
PubMed2002

Five-year experience with valve sparing surgery for aortic root aneurysms.

BACKGROUND: The aim of this study was to analyze the mid-term results of aortic root reconstruction. METHODS: Between September 1995 and March 2001, 32 patients (25 males, 7 females, median age 58 +/- 21 years) underwent aortic root reconstruction as described by T. David. Indications for operation were aortic insufficiency with ascending aortic aneurysm in 27 patients, and acute aortic dissection (Stanford type A) in 5 patients. In all patients the native valve was preserved and suspended inside a tubular prosthesis with reimplantation of the coronary arteries. In 10 patients the classic reconstruction technique was modified by shaping a "Neosinus." RESULTS: There was one perioperative death due to myocardial infarction. Two patients suffered a stroke. 26 patients were followed up 12 months postoperatively. 22 out of 26 patients were in NYHA functional class I, 2 patients in class II and the remaining 2 in class III. Three patients died in the postoperative period. Six patients had trivial AR, 4 mild and 1 moderate regurgitation. There were no thromboembolic events during follow up. The mean transvalvular gradient was 3.5 +/- 2.2 mmHg. Compared to a normal cohort of patients (n = 20), resuspended aortic valves opened (26.4 +/- 5.8 vs. 61.3 +/- 22.1 cm/sec, p < 0.0001) and closed (22.8+/- 6.9 vs. 57.9 +/- 22.3) at a higher speeds and also showed shorter opening (0.053 +/- 0.12 vs. 0.023 +/- 0.09 sec, p < 0.0001) and closing times (0.051 +/- 0.07 vs. 0.23 +/- 0.07 cm/sec) of the aortic leaflets. CONCLUSIONS: Aortic valve reimplantation is a reliable technique able to reduce long term complications when compared to conventional composite graft replacement of the aortic root. Altered leaflet opening and closing dynamics do not impair midterm durability.

Adolescent↗
PubMed2002

Optimal carbon dioxide application for organ protection in cardiac surgery.

BACKGROUND: Cardiac surgery is associated with an important risk of central or peripheral organ damage, attributed in part to air embolism from incompletely deaired cardiac chambers. Insufflation of carbon dioxide into the thoracic cavity is widely used for organ protection in cardiac surgery. METHODS: In patients operated on through a sternotomy, the gas was insufflated through a standard cardioplegia line (group I, n = 10) or a Jackson-Pratt drain (group II, n = 10), with flow rates of 2, 4, and 6 L/min. In patients undergoing mitral valve surgery through a right anterolateral minithoracotomy, application through a gas port (group III, n = 10) was compared with application through a Veress needle (group IV, n = 10). In groups I and IV measurements were repeated with a gauze sponge to divert the gas stream. RESULTS: At a flow of 2 L/min, carbon dioxide levels in the thoracic cavity reached 52% +/- 30% in group I and increased to 81% +/- 27% when a gauze sponge was used. In group II a level of 91% +/- 5% was achieved. In minimally invasive procedures carbon dioxide levels reached 92% +/- 6% in group III and 60% +/- 25% in group IV without a gauze sponge and 97% +/- 2% in group IV with a gauze sponge. Increasing flow rates from 2 to 6 L/min decreased carbon dioxide levels in the thoracic cavity. Arterial blood gas analysis did not reveal critical levels of partial pressure of carbon dioxide at any time. CONCLUSIONS: For optimized carbon dioxide concentrations during cardiac procedures, jet effects in the thoracic cavity have to be avoided. The highest levels were achieved with infusion lines covered by a gauze sponge or a perforated drain for conventional operations and a sponge-covered Veress needle or a gas port for minimally invasive approaches.

Carbon Dioxide↗
PubMed2001

Long term follow up of left ventricular function after repair of left ventricular aneurysm. A comparison of linear closure versus patch plasty.

OBJECTIVE: Suboptimal early and unsatisfactory late results after linear closure of left ventricular aneurysms, have focused attention on more physiologic concepts of aneurysmectomy, like endoventricular patch plasty. The aim of our study was to compare clinical results of linear closure and patch plasty 8 years after surgery. METHODS: From a total of 102 patients with postinfarctional left ventricular aneurysms, clinical outcomes and echocardiographic measurements of left ventricular function in 32 patients who underwent linear closure were compared to those of 20 patients who had endoventricular patch plasty. RESULTS: The two groups were matched with respect to age, gender, comorbid risk factors, functional class, urgency of the operation and concomitant procedures. In the patch plasty group, ejection fraction increased from 33.1+/-12.2% to 34.4+/-9.7%. In the linear closure group, ejection fraction decreased from 44.3+/-10.9% to 40.1+/-7.9%. Perioperative mortality and complications, long term survival and functional class were similar in both groups with a total perioperative mortality of 1.9%, an 8-year survival rate of 85.6%, and a mean NYHA functional class of 2.51. CONCLUSION: Long-term follow up showed a decline in ejection fraction in the direct closure group and a slight increase in the patch plasty group. We suggest that linear closure should be limited to small ventricular aneurysms and that large ventricular aneurysms extending into the septum should be treated by patch plasty.

Aged↗
PubMed2001

Fate of bypass grafts onto totally occluded coronary arteries.

BACKGROUND: Chronically occluded coronary arteries often develop good collateralisation, that leads to retrograde perfusion of these vessels, as regularly seen in coronary angiograms. Retrograde perfusion constitutes a form of competitive flow, which in turn is associated with an increased risk for early bypass graft failure. The aim of our study is to investigate the patency rate of bypass grafts onto totally occluded coronary arteries, in the presence of retrograde flow. METHODS: Two groups of patients were followed up by cardiac catheterisation. One month after undergoing coronary artery bypass grafting. Group 1 (n=33) had coronary three vessel disease, with one totally occluded coronary artery and evidence of retrograde flow in the preoperative coronary angiogram. Group 2 (n=30) was the control group, with coronary three vessel disease and without totally occluded coronaries. We used internal mammary arteries and saphenous vein grafts as conduits. RESULTS: Thirty-six point thirty-six per cent of bypass grafts onto totally occluded coronaries were occluded one month postoperatively (n=12). Graft failure in the control group was 13.3%. Significance p=0.03. CONCLUSIONS: In view of our findings we conclude, that there is a significantly increased incidence of early graft failure, when totally occluded coronary arteries are revascularised, that show retrograde flow in the preoperative coronary angiogram.

Coronary Angiography↗
PubMed2000

Leaflet escape in a TEKNA and an original duromedics bileaflet valve.

We report a case of leaflet escape in an Edwards-TEKNA bileaflet valve, in the mitral position. The examination findings of the explanted valve are compared with a similar case of leaflet escape in an original Edward-Duromedics prosthesis. Based on our findings alone, it is not certain whether the TEKNA valve continues to have a higher risk for fracture.

Adult↗
PubMed1999

New mutations of the hydroxymethylbilane synthase gene in German patients with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is a low-penetrant, autosomal dominant disorder caused by decreased activity of hydroxymethylbilane synthase (HMBS; MIM 176 000), the third enzyme in the heme biosynthetic pathway. We report the first molecular analysis of HMBS gene mutations in classical AIP patients of German origin. The HMBS gene of 5 German AIP patients was analysed by DGGE-screening and direct sequencing of amplified genomic DNA. Five different mutations including four novel mutations were found. Three of them are single base substitutions that affected exon 3 (R16C), exon 10 (V202L), and intron 13 (T to A, IVS13+2) The two remaining mutations are frameshifts which produce a stop codon (del GA in exon 6 and insA in exon 14). These mutations are likely to be responsible for the decrease in HMBS activity found in both erythrocytes and non-erythroid cell lines (lymphocytes). Our results demonstrate the allelic heterogeneity of HMBS mutations in AIP patients of German origin.

Adolescent↗