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Biomedical subjects

Anton Moritz

Publications and source records attributed to Anton Moritz.

At least 19 recordsLinked to original sources
PubMed2007

Medium-term follow-up and modes of failure following epicardial pacemaker implantation in young children.

AIMS: Young children suffering from congenital or post-operative AV-block require life-long pacemaker stimulation. Due to the anatomical prerequisites initially epicardial electrodes are implanted and the generator is placed in the upper abdominal wall. The following study investigated modes of failure leading to reoperation in this group of technically challenging patients. METHODS AND RESULTS: Between October 2000 and May 2005, a total of 21 infants (age 3 days to 5 years) underwent pacemaker implantation using a subxyphoidal incision for newborns (and a partial lower or complete median sternotomy for older children). Nine patients had previous cardiac surgery for complex congenital defects. The remaining 12 young children suffered from congenital AV-Block (CAVB). Twenty-one bipolar epicardial electrodes (Medtronic Capsure epi) were fixed to the right ventricle, 15 had additional implantation of a bipolar atrial lead. The pacemaker generator (Medtronic Kappa 701) was implanted into the right upper abdominal wall. Indications for revision were recorded. No mortality was observed; pacing and sensing parameters remained stable up to a 5-year follow-up. A total of four reoperations occurred. Three of the four revisions were caused by ventricular electrode fracture. At revision, two electrodes were broken at the crossing between the pericardial cavity and the abdominal wall, one bipolar lead at the Y-division into the two tip electrodes. One reoperation was due to a pacemaker recall. All revisions were performed without complications. CONCLUSION: In our institute epicardial pacing in young children was associated with a satisfactory clinical outcome, but also a significant number of failures leading to reoperation, mainly due to electrode fracture caused by the muscular activity of this patient group. Reoperations were performed at a low risk.

Cardiac Pacing, Artificial↗
PubMed2006

Assessment of coronary artery bypass grafts patency with different magnetic resonance technologies.

OBJECTIVE: The aim of the study was to evaluate the diagnostic accuracy of different magnetic resonance (MR) sequences in the assessment of coronary artery bypass graft patency and the evaluation of distal anastomoses with a spin echo sequence (Haste). PATIENTS AND METHODS: Twenty-five patients were examined with all the three techniques and 185 patients with 481 distal anastomoses were examined with the Haste sequence at a 1.5 TMR scanner and coronary angiography. A two-dimensional T(2)-weigthed breath-hold half-Fourier acquisition single-shot turbo spin echo sequence (Haste), a Navigator sequence and a gadolinium-enhanced Fisp-3-D sequence were performed. All images were evaluated independently by a radiologist and cardiologist and compared to the conventional coronary angiography. The observers were blinded to the coronary angiography findings, but informed in regard to the surgical graft anastomosis. RESULTS: With the Haste sequence 80% of the distal anastomoses were recognized. The sensitivity and specificity for the evaluation of the distal anastomosis with the Haste sequence was 94% and 75%. The Navigator and the Fisp-3-D sequences showed a sensitivity of 74% and 94% and a specificity of 78% and 88%. CONCLUSION: The best results were achieved with the Haste sequence, a reliable assessment of graft patency of the distal anastomosis is possible. The best imaging of proximal IMA segments was possible with the Fisp-3-D sequence. Due to the low sensitivity and specificity, the use of the Navigator sequence was stopped in our center. Further improvements of the spatial resolution and the image quality are necessary to recommend this MR techniques for routine clinical use.

Aged↗
PubMed2006

[Endovascular interventions of the descending thoracic aorta].

Endovascular interventions of the descending thoracic aorta have been established as an alternative to conventional open surgery. Initially, they were limited to elective patients with a high risk profile for open surgery, but soon their use was extended to emergencies as well. In the elective setting, endovascular interventions significantly lowered short-term morbidity and mortality. These excellent perioperative results were reproducible in the emergency setting, thereby leading to superior outcomes for patients treated by endovascular stent grafts when compared to the conventional open surgical approach. However, some questions regarding long-term durability of these devices remain unanswered. Stent-graft failures at mid and long-term follow-up have been reported in the literature. The progressive nature of stent graft-related mid- and long-term complications stresses the need for continued surveillance of these patients.

Aortic Dissection↗
PubMed2006

[Indication, technique, and results of aortic valve and ascending aorta reconstruction].

Aortic valve replacement is the standard procedure in patients with aortic valve regurgitation (AR). Although long-term results for both biological and mechanical heart valves could be improved, a valve-sparing operation has several advantages especially in young patients. Alterations in the geometry of the aortic root, especially dilatation of the sinutubular junction, are the primary cause of AR in patients with aneurysms of the ascending aorta. In patients with a bicuspid aortic valve, AR is usually caused by a prolapse; with appropriate surgical experience, the prolapse can be corrected and the valve reconstructed. Isolated reconstruction of a tricuspid aortic valve such as decalcification, commissurotomy or plication of ring or leaflets are seldom indicated. The recontstructive techniques for aortic root aneurysms or type A dissection described by David and Yacoub have become routine procedures over the last decade. The long-term clinical results are excellent, and revision and thromboembolism rates are very low. A maximal diameter of the aortic root > 5 cm is indicative for performing the above procedures. This technique has been used in the own clinic since 1996 with excellent clinical and echocardiographic results. Only four of 101 patients operated had a moderate AR during the follow-up period. The reconstruction of a prolapse in a bicuspid aortic valve is possible by using an autologous, fixed pericardial patch, with very good long-term results. By using this surgical technique, two geometrically correct pockets with a broad coaptation zone can be constructed. In 36 of the patients operated in the own clinic, only four patients showed grade I AR. No patient had to undergo reoperation. An aortic valve reconstruction for an isolated leaflet perforation following a healed endocarditis is seldom indicated.In the authors' opinion, valve-sparing reconstruction in cases of aneurysms of the ascending aorta, and for bicuspid valves, represents a promising alternative to prosthetic valve replacement. With low surgical mortality and morbidity, excellent clinical and functional long-term results can be achieved. Furthermore, the lack of the necessity of anticoagulation as well as positive hemodynamic factors argue for a valve-sparing surgical technique. A final evaluation of the method is not possible, however, until long-term follow-up of up to 20 years is available and the positive results have been confirmed.

Adult↗
PubMed2006

Left ventricular remodeling impacts the function of the Quattro stentless mitral valve bioprosthesis (a 4-year experience).

OBJECTIVE: The St Jude Quattro stentless mitral valve prosthesis (QMV) is sutured to the mitral annulus and the papillary muscle heads, thereby preserving the subvalvular apparatus. After mitral valve replacement, remodeling of the left ventricle is often observed, causing a dilated ventricle to shrink in diameter. It was our objective to assess these changes in left ventricular (LV) geometry and evaluate its effects on the function of the QMV. METHODS: From September 1997 to October 2000, 24 patients received QMV at our institution. The patients were followed up at yearly intervals (mean 4.1 +/- 2.2 years). All pre- and postoperative echocardiograms were evaluated, with attention focused on the subvalvular apparatus, leaflet morphology, and occurrence of late mitral regurgitation. In addition, all clinical outcomes and valve-related complications were recorded. RESULTS: Forty-one percent of patients (10/24) developed late mitral regurgitation (mild, n = 5; moderate, n = 5). The site of regurgitation was located at the 2 commissures in all cases. In 8 patients, changes in LV diameter had occurred. The point of leaflet coaptation had shifted away from the annulus in 4 patients. The overall mortality was 12.3%, and the postoperative stroke rate was 12.3%. CONCLUSIONS: Midterm changes in LV geometry seem to affect the competence of the QMV. Predicting these changes and subsequently adapting the sizing procedure remain a challenging task. The high rate of late valve incompetence and poor clinical outcomes has prompted us to discontinue recruitment of patients for this trial.

Bioprosthesis↗
PubMed2006

Two hundred forty minimally invasive mitral operations through right minithoracotomy.

BACKGROUND: This study reports of our 7-year experience with minimally invasive mitral valve operations using the transthoracic clamp technique, reviewing morbidity and mortality as well as echocardiographic follow-up results. METHODS: Between 1997 and 2004, 241 patients (121 male; aged 56 +/- 14 years) underwent minimally invasive mitral valve surgery through right thoracotomy using the transthoracic clamp technique. Reconstructions were done in 199 patients, and 42 valves were replaced. Mean length of incision was 7.0 +/- 1.2 cm. Mean preoperative New York Heart Association functional class was 2.6 +/- 0.9. RESULTS: Thirty-day mortality was 3.3% (n = 8). Operating, bypass, and cross-clamp times averaged 241 +/- 52, 142 +/- 40, and 84 +/- 26 minutes, respectively. Seven patients (2.9%) had conversion to sternotomy. Nine patients (3.7%) underwent reexploration for bleeding. Mean intensive care unit and hospital stay were 18 hours and 8.1 days, respectively. Mean follow-up was 30 +/- 18 months (range, 3 to 76). Echocardiographic follow-up documented persistently competent valve function in all but 6 patients who had grade III regurgitation. Five of them underwent mitral valve re-reconstruction and 1 underwent transplantation. At 76 months, freedom from nontrivial recurrent mitral regurgitation and reoperation were 92.3% and 96.2%, respectively. Actuarial survival at 76 months, including early mortality, was 90.7%. Thoracic wounds were free from infection in all patients. CONCLUSIONS: This study demonstrates that the direct vision, transthoracic clamp technique for minimally invasive mitral valve surgery is reproducible with low mortality and morbidity rates. It results in excellent cosmesis and abolished the risk of thoracic wound infection. Results are comparable to midterm outcomes of conventional operations.

Adolescent↗
PubMed2006

Seven years' experience with suture annuloplasty for mitral valve repair.

OBJECTIVE: Our early experience with the mural annulus shortening suture procedure for mitral valve repair showed superior hemodynamic performance over ring annuloplasty. The aim of this study was to assess the durability of the mural annulus shortening suture procedure and evaluate our 7-year experience regarding valve function, hemodynamic performance, and clinical outcome. METHODS: Between 1996 and 2003, 222 elective consecutive patients (58.1% males; age, 59 +/- 14 years) underwent simple or complex mitral valve repair. Minimal invasive reconstruction was performed in 150 patients. For correction of annular dilatation, we used double-running 2-0 polytetrafluoroethylene sutures to reinforce the posterior circumference of the annulus. Patients were investigated prospectively by means of transthoracic echocardiography before discharge and 1 and 5 years after the operation. The mean follow up was 32 +/- 21 months (range 1-77 months). RESULTS: The operative mortality was 3.1%. Hemodynamic performance at 1 and 5 years showed low mean transvalvular gradients (2.1 +/- 0.9 and 2.0 +/- 0.8 mm Hg, respectively) and a calculated mitral valve orifice area of 3.3 +/- 0.9 cm2 and 3.1 +/- 0.6 cm2, respectively, with progressive annular dilatation from 31.2 +/- 3 mm to 33.9 +/- 4 mm at 1 year and 35.7 +/- 4 mm at 5 years (P < .01). Clinical status improved from New York Heart Association class 3.0 +/- 0.4 to 0.6 +/- 0.8 at 1 year and 0.8 +/- 0.8 at 5 years. Freedom form nontrivial residual mitral regurgitation was 82.3%, freedom from reoperation was 95.1% and actuarial survival was 87.2%, all at 77 months. CONCLUSIONS: The midterm results show satisfactory hemodynamic performance and clinical improvement. Valve competence and reoperation rates are comparable with those of other reports. Durability of the mural annulus shortening suture procedure for mitral valve repair is questioned because progressive annular redilatation occurs.

Female↗
PubMed2006

Stentless bioprostheses improve postoperative coronary flow more than stented prostheses after valve replacement for aortic stenosis.

OBJECTIVE: In some randomized studies, stentless aortic valves have demonstrated hemodynamic advantages in comparison with stented prostheses. The effect of more physiologic flow dynamics on coronary artery flow has not been investigated yet. This study compares coronary perfusion after aortic valve replacement with stented or stentless porcine bioprostheses in a prospective randomized study. METHODS: A total of 24 patients (73 +/- 6 years) referred for treatment of aortic stenosis were randomized to aortic valve replacement with stented (Medtronic Mosaic; (Medtronic Inc, Minneapolis, Minn) or stentless (Medtronic Freestyle; Medtronic Inc) prostheses. Coronary flow was measured by means of magnetic resonance imaging preoperatively, 5 days after the operation, and 6 months postoperatively, then with evaluation of coronary flow reserve. Echocardiography was performed to quantify transvalvular gradients and left ventricular mass regression. RESULTS: Coronary flow increased in both groups significantly (P < .001) after aortic valve replacement. This increase was higher in the stentless group compared with that seen in the stented group (343 +/- 137 vs 221 +/- 66 mL/min). Also, coronary flow reserve was higher for stentless valves (3.4 +/- 0.3 for stentless valves and 2.3 +/- 0.1 for stented valves). Mean pressure gradients for Freestyle valves were lower (10 +/- 4 and 8 +/- 3 mm Hg, respectively, vs 19 +/- 6 postoperatively and 15 +/- 4 mm Hg at follow-up for Mosaic valves, P < .05). Left ventricular mass regression was similar in both groups. CONCLUSIONS: Normalization of coronary artery flow after aortic valve replacement for aortic stenosis was more pronounced for stentless valves compared with stented valves. The fact that the stentless design also demonstrated a superior hemodynamic performance with lower pressure gradients might be explained by the design being closer to physiologic anatomy and thus the presence of lower turbulence levels in the sinuses of Valsalva.

Aged↗
PubMed2006

Perioperative biventricular pacing leads to improvement of hemodynamics in patients with reduced left-ventricular function--interim results.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been introduced as a new therapeutic modality in patients with chronic heart failure. However, most studies have investigated the hemodynamic effects in congestive, but not postoperative heart failure. OBJECTIVE: The following study investigates hemodynamic effects of perioperative temporary biventricular pacing in patients undergoing open heart surgery. In 54 patients one left and one right ventricular epicardial wire was placed during open heart operations. Hemodynamic parameters were measured immediately after the operation and 6 as well as 24 hours postoperatively. Transesophageal echocardiography was performed 1 hour postoperatively. RESULTS: Of the 54 patients (59.2%), 32 responded to biventricular pacing with an increase in cardiac output; in these patients synchronized ventricular contraction could be verified echocardiographically. This hemodynamic benefit persisted 6 hours and 24 hours postoperatively. The remaining 22 patients did not show any hemodynamic improvement from biventricular stimulation. CONCLUSION: Biventricular pacing leads to significant rise in cardiac output in approximately 59% of patients with severely reduced left ventricular function and widened QRS complexes. Further studies are necessary to define clearly the clinical characteristics of patients who show remodeling by CRT.

Aged↗
PubMed2006

Imaging of calcified coronary arteries with multislice computed tomography.

Reliable noninvasive detection of coronary artery disease is a prime goal in clinical cardiology. The aim of this study was to investigate the accuracy of multislice computed tomography in detecting coronary artery disease in correlation to the calcium score. Fifty patients with 61 stenoses > 50% and 41 occlusions underwent multislice computed tomography and conventional coronary angiography. Calcium scoring was calculated for the total coronary artery territory and patients were divided into 3 groups based on this score. Multislice computed tomography visualized 89% (365/500) of all coronary segments. The sensitivity and specificity for detection of stenoses > 50% or occlusion was 47%-92%, and 97%-100% for the calcium score. Forty of 500 segments were underestimated by multislice computed tomography, of which 39 were in the group with a calcium score > 400. Multislice computed tomography allows noninvasive angiographic evaluation of coronary artery disease with high diagnostic accuracy. However, the method strongly depends on the degree of vascular calcification and underestimates the degree of stenosis according to the calcium score. This new technology holds promise for noninvasive risk assessment in patients with known or suspected coronary artery disease.

Calcinosis↗
PubMed2006

Evaluation of the spatial resolution with 1.5-4 tesla in a stenosis model.

Since it was first described in the early 1990s, magnetic resonance coronary angiography has evolved into a promising noninvasive modality for imaging the coronary arteries. The aim of this study was to evaluate the detection accuracy and spatial resolution of vascular stenosis in contrast-enhanced 3-dimensional magnetic resonance angiography on a flow phantom. The examinations were performed with 1.5, 3, and 4 T whole-body imaging systems. For imaging at 4 T, we used a gradient-echo-multi-slice sequence. The system was flushed with gadopentetate dimeglumine contrast medium at flow rates of 40 and 60 mL.min(-1). The accurate detection of in vitro stenoses was possible in segments of 0.4 mm in diameter at 4 T. The best results were obtained at a flow velocity of 40 mL.min(-1) and a contrast medium concentration of 0.2 mmol.L(-1). Contrast-enhanced high-field 3-dimensional magnetic resonance imaging provided a highly accurate evaluation of the degree of stenosis in this model. Exact evaluation of vessel diameters < 0.4 mm was not possible, even with 4 T. In vivo studies are necessary to overcome the current limitations in the visualization of small distal vessel segments.

Coronary Stenosis↗
PubMed2006

The use of minimized extracorporeal circulation system has a beneficial effect on hemostasis--a randomized clinical study.

BACKGROUND: Conventional cardiopulmonary bypass (CPB) is associated with increased coagulation and fibrinolytic activity. A closed miniaturized bypass circuit (CorX) features a significantly reduced tubing set, an integrated pump, and an air removal system without a cardiotomy reservoir. In a prospective randomized trial, the effects on hemostasis were investigated while comparing CorX with conventional CPB in patients undergoing coronary artery bypass grafting. METHODS: Over a period of 1 year, 81 patients were randomly assigned either to the CorX system (n = 39, group A) or standard CPB system (n = 42, group B). Primary endpoints were platelet count, plasmin-antiplasmin complex (PAP), prothrombin fragments 1+2 (F1+F2), D-dimers, and fibrinogen. Secondary end-points were hematocrit, blood loss in the first 12 hours postoperatively, transfused packed red blood cells, and fresh frozen plasma in the first 24 hours postoperatively. In addition, we analyzed partial thromboplastin time, prothrombin time, and antithrombin III. RESULTS: After aortic declamping, PAP complex and prothrombin F1+F2 were significantly lower in group A than in group B. The difference in D-dimers between groups reached significance at 1 hour post-CPB. Hematocrit values at the end of CPB measured 26 +/- 6% in group A versus 22 +/- 4% in group B (P = .01). The rest of the observed parameters did not significantly differ between groups. CONCLUSION: Postoperative blood loss was not reduced in the present study. However, the use of the CorX system leads to a significant suppression of activation of coagulation and fibrinolytic cascades compared to conventional CPB, suggesting that miniaturized extracorporeal circuits are a step forward toward reduced imbalance of hemostasis in cardiac surgery.

Aged↗
PubMed2006

Impact of mechanical and biological aortic valve replacement on coronary perfusion: a prospective, randomized study.

BACKGROUND AND AIM OF THE STUDY: Coronary perfusion is impaired in patients with aortic stenosis (AS). Aortic valve replacement (AVR) leads to improvement, but not complete restoration, of coronary flow. Previous studies have shown that postoperative coronary flow rate and coronary reserve in mechanical valves is dependent on valve design and orientation. The study aim was to investigate acute changes in coronary perfusion in patients undergoing mechanical or biological valve replacement in a prospective, randomized clinical study. METHODS: Forty patients undergoing AVR for AS underwent MRI scanning to measure coronary flow preoperatively and at five days after surgery. Patients scheduled for mechanical AVR (n = 20) were randomized to a tilting disc (Medtronic Hall) or bileaflet (Medtronic ADVANTAGE) prosthesis; the biological-valve group (n = 20) received a stented (Medtronic Mosaic) or stentless (Medtronic Freestyle) valve. Valve sizes were comparable in all groups. Patients also underwent echocardiography both preoperatively and postoperatively to measure transvalvular pressure gradients. The rate-pressure product (RPP) was calculated as a marker of myocardial oxygen demand and cardiac workload. RESULTS: The mean preoperative coronary flow rate was 90 +/- 32 ml/min, and this increased after AVR in all patients. The rise in the mechanical-valve groups was comparable for the two tested valves, whereas in the biological-valve groups a significantly higher increase for stentless valves was present (p < 0.05). Mean pressure gradients for the Hall and ADVANTAGE valves were equal; for biological valves, the Mosaic demonstrated a higher mean gradient (19 +/- 6 mmHg) than the Freestyle (10 +/- 4 mmHg) (p < 0.05). The RPP was lower for ADVANTAGE (mechanical group) and for Freestyle valves (biological group). CONCLUSION: Coronary artery flow was increased following AVR in all valve groups. The rise was significantly more distinct for Medtronic Freestyle stentless valves compared to the three other valve substitutes. As the stentless design also demonstrated superior hemodynamics and a lower myocardial oxygen demand with lower pressure gradients and lower RPP, this may have a positive impact on the clinical long-term outcome of this valve.

Age Factors↗
PubMed2006

Annular compression stitch for quadrangular resections in mitral valve repair.

BACKGROUND AND AIM OF THE STUDY: Quadrangular resections for posterior mitral leaflet prolapse create a defect that requires readaptation of the annulus as well as the leaflet cut edges. A variety of techniques has been described to narrow the posterior mitral annulus. Herein is described a simple compression stitch that allows compensation of annular size reduction even for large resections of the mural leaflet. METHODS: The annular compression stitch consists of four bites: the first stitch is placed from the atrium into the ventricle; the second takes a piece of ventricular myocardium parallel to the mitral ring; the third returns the needle into the atrium some millimeters outside the opposite cut edge of the mitral leaflet; and the fourth stitch grabs atrial myocardium parallel to the previous ventricular stitch. Tying the knots compresses the annulus to an extent that allows reanastomosis of the two leaflet cut edges. RESULTS: This new technique was used in 212 patients undergoing mitral valve repair. Intraoperative outcome was excellent, and after a mean follow up period of 2.5 years no reoperation was needed due to failure of the annular compression stitch. CONCLUSION: The new compression stitch simplifies the repair, avoids the creation of a trench, and allows readaptation of the two mural leaflet edges without tension, even in large posterior resections.

Cardiac Surgical Procedures↗
PubMed2006

The radial artery as a conduit for coronary artery bypass grafting: review of current knowledge.

The effect of coronary artery bypass grafting (CABG) lasts as long as the grafts are patent. The internal mammary artery has been considered the "golden" graft due to the superb long-term patency, exceeding 90% at 10 years. The saphenous vein grafts, unfortunately, tend to occlude with a rate of 10-15% within a year after surgery, and eventually, at 10 years after the operation, as much as 60-70% of these vein grafts are either occluded or have angiographic evidence of atherosclerosis. The search for another "arterial conduit", the radial artery, has intensified through the last 15 years in hope to provide a better graft than the saphenous vein for CABG. This article reviews the current knowledge for the radial artery as a conduit in CABG.

Coronary Artery Bypass↗
PubMed2005

Disseminated Aspergillus fumigatus infection with consecutive mitral valve endocarditis in a lung transplant recipient.

Aspergillus infection is a known complication of lung transplantation and remains associated with high mortality rates. The manifestation of the infection varies from simple colonization of the lung to disseminated complicated infections. Early Aspergillus infection has been rarely observed in a small number of lung transplant recipients; most cases occur during the late post-operative period. The pulmonary involvement has often been described as the first clinical localization of the disease. Although other various forms of Aspergillus infection are not uncommonly encountered after lung transplantation, Aspergillus mitral valve endocarditis is rare. We present a case of disseminated Aspergillus fumigatus infection with consecutive mitral valve endocarditis having developed 78 days after double-lung transplantation for cystic fibrosis.

Adult↗
PubMed2005

Degradation of microvascular brain endothelial cell beta-catenin after co-culture with activated neutrophils from patients undergoing cardiac surgery with prolonged cardiopulmonary bypass.

The adhesion of highly activated neutrophils to cerebral microvascular endothelial cells (MVECs) may contribute to disruption and hyperpermeability of the blood-brain barrier (BBB) after cardiac surgery with prolonged cardiopulmonary bypass (CPB). A correlation between CPB duration and neutrophil-mediated BBB damage has not been investigated on the cellular level yet. Therefore, we studied the effects of neutrophils from cardiac surgery patients with CPB time <80 min (group I; n=8) and >80 min (group II; n=8) on the integrity of cultured porcine MVEC. Ex vivo, neutrophils of group II but not of group I significantly degraded the zonula adherens molecule beta-catenin whereas VE-cadherin and occludin were not modified. The transendothelial electric resistance as a measure for the integrity of the endothelial monolayers was reduced over time in both groups. In conclusion, prolonged CPB time entails neutrophil-mediated decrease in MVEC beta-catenin expression, and thus may be an important trigger for BBB disruption.

Animals↗