Adjustable spatial filter for optimal free-space quantum communication round the clock.

Free-space quantum communication in daylight relies crucially on spatial filtering. The optimal filter configuration, however, depends on ever-changing link conditions. To this end, we developed an adjustable spatial filter that can be used to change the system field of view on the fly. We demonstrate its use in quantum key distribution over a 1.7-km free-space link. Furthermore, we compare it to filtering with multi-mode fiber coupling. Finally, we extrapolate our results to a broader range of realistic link conditions and show that active field-of-view optimization has the potential to substantially improve the overall secure key output of the system.

Significant value of autopsy for quality management in cardiac surgery.

OBJECTIVE: With recent advances in diagnostic imaging, the value of autopsy has been called into question. The aim of our study was to assess the current impact of autopsy for early postoperative quality management in cardiac surgery. METHODS: Between 2000 and 2003, a total of 14,313 patients underwent cardiac surgery at our center. Of these, 898 patients (6.3%) died, and autopsy was performed in 468 cases (52.1%). Data from clinical and postmortem examination were prospectively analyzed regarding causes of death, postoperative complications, concomitant diseases, and surgery-associated pathologic findings. RESULTS: Mean age was 68.7 years. Mean survival was 13.9 postoperative days. On autopsy, causes of death were cardiac in 49.8% of cases (n = 233), respiratory in 8.3% (n = 39), cerebral in 6.4% (n = 30), abdominal in 4.7% (n = 22), multiorgan failure or sepsis in 14.9% (n = 70), pulmonary embolism in 6.6% (n = 31), procedure associated in 8.3% (n = 39), and others in 0.9% (n = 4). Discrepancies between clinical and postmortem determinations of cause of death were found in 108 cases (23.1%). These were acute myocardial infarction (n = 38), low cardiac output (n = 9), respiratory (n = 8), cerebral (n = 5), abdominal (n = 7), multiorgan failure or sepsis (n = 12), pulmonary embolism (n = 18), and procedure associated (11). Clinically unrecognized postoperative complications were found in 364 cases (77.8%). Unknown concomitant diseases were found in 464 cases (99.1%), with potential therapeutic relevance in 90 cases (19.2%). In 85 cases (18.2%), autopsy examination revealed 96 premortem unrecognized surgery-associated pathologic findings. CONCLUSION: A high overall discrepancy rate between premortem and autopsy diagnoses was recognized. Autopsy revealed clinically relevant information in a significant number of cases. Therefore autopsy remains essential for quality assessment in perioperative treatment.

Clinical experience with stentless mitral valve replacement.

BACKGROUND: Our aim is to describe the clinical experience with stentless mitral valve (SMV) replacement with special focus on the functionality of the SMV. METHODS: Fifty-two patients (68 +/- 8.5 years old; 36 female) have been prospectively evaluated since August 1997. The chordally supported SMV (Quattro) was implanted for mitral stenosis (n = 26), severe incompetence (n = 17), or mixed lesion (n = 9). Preoperative New York Heart Association class was 3.1 +/- 0.6. Twenty patients received additional intraoperative ablation therapy. Mean follow-up is 37.3 +/- 18.7 months (range, 1 to 65). RESULTS: Surgery was performed using conventional sternotomy (33) or anterolateral minithoracotomy (19). Atrial rhythm was reestablished in 17 of 20 patients. Six patients operated on early in this series required reoperation, 2 for paravalvular leakage, 2 for functional stenosis, 1 with pannus formation due to underlying rheumatoid disease, and 1 for papillary flap rupture after 5.1 years. Mortality was 1 perioperative (1.9%, nonvalve related) and 1 after reoperation due to multiorgan failure. During late follow-up (30 +/- 7 months postoperatively) 5 patients died of noncardiac causes. Regular echocardiographic control revealed good SMV function (maximum transmitral blood flow velocity 1.7 +/- 0.2 m/s; mean transmitral pressure gradient 3.9 +/- 1.2 mm Hg) and well-preserved ejection fraction postoperatively as well as at most recent follow-up. CONCLUSIONS: The clinical experience after 5.5 years of SMV implantation is promising. Preservation of annuloventricular continuity is advantageous. However, long-term durability remains to be proved.

Early results with stentless mitral valve replacement.

BACKGROUND AND AIM OF THE STUDY: Implantation of a chordally supported stentless mitral valve (SMV) may be the strategy of choice for patients with severe degenerative mitral valve disease. Herein, the early clinical results of this surgical technique were analyzed. METHODS: Since August 1997, 52 patients (36 females, 16 males; mean age 68.0 +/- 8.5 years) each received a SMV (Quattro; St. Jude Medical Inc.) at the authors' institution. The underlying disease was predominant mitral stenosis (n = 26), incompetence (n = 17) and combined lesion (n = 9). The mean NYHA class was 3.1 +/- 0.6, left ventricular ejection fraction 64 +/-13%, and cardiac index 2.1 +/- 0.8 1/min/m2. RESULTS: SMV implantation was performed using either a conventional sternotomy (n = 33) or a lateral minithoracotomy (n = 19). The mean implanted valve size was 29.2 +/- 1.7 mm, and mean cross-clamp time 81 +/- 33 min. Reoperation was required in six patients: two for paravalvular leakage, two for functional stenosis (both 26 mm valves), in one patient for pannus formation with underlying collagenosis, and in one for papillary flap rupture at five years. One patient died perioperatively, one died after reoperation at one year, and five patients died at longer follow up, from non-cardiac causes. Hemodynamic function was shown to be normal on echocardiography. CONCLUSION: Intermediate-term results after SMV implantation were promising. Preservation of annuloventricular continuity led to good left ventricular function, but long-term durability remains to be proven.

Restitution of sinus rhythm plus stentless mitral valve replacement at three years.

BACKGROUND AND AIM OF THE STUDY: The study aim was to examine results after stentless mitral valve (SMV) replacement (Quattro) and restitution of physiological cardiac rhythm by intraoperative left atrial ablation therapy. METHODS: Twenty patients (13 females; mean age 69.7 +/- 5.9 years) with severe degenerative mitral valve disease (six with valve stenosis, six with valve incompetence, eight with combined lesion) were prospectively evaluated since 1998. The mean NYHA functional class was 3.2 +/- 0.4, and cardiac index 1.8 +/- 0.5 l/min/m2. Ablation therapy was performed by inducing left atrial linear lesion lines to avoid reentrant circuits. RESULTS: Surgery was performed using conventional sternotomy (n = 10) or lateral minithoractomy (n = 10). Sinus rhythm was successfully restituted in 17 patients either postoperatively or in the long term (success rate 85%). However, three patients required DDD-pacemaker implantation, and another three had to be discharged with persistent atrial fibrillation. Intermittent medical therapy (sotalol or amiodarone) was required in nine patients postoperatively, in four patients at six months, and in two patients at one-year follow up. One patient was reoperated on for paravalvular leak after one year, but subsequently died due to sepsis. In the other patients, echocardiographic control proved good SMV function with atrial contraction. CONCLUSION: Restitution of physiological cardiac function is possible by combined stentless MV implantation and left atrial ablation therapy. A persistent benefit, without need for additional re-intervention, was shown at mid-term follow up.

Midterm results after stentless mitral valve replacement.

BACKGROUND: To analyze the midterm clinical results after stentless mitral valve (SMV) replacement. METHODS AND RESULTS: Fifty one patients (68.3+/-8.4 years, 35 female) with severe mitral valve disease (stenosis 25, incompetence 17, mixed lesion 9) received a chordally supported SMV (Quattro, St. Jude Medical Inc.) since August 1997. Preoperative New York Heart Association class was 3.1+/-0.6; left ventricular ejection fraction 64+/-13%, and cardiac index 2.1+/-0.8 l/min/m2. Additional intraoperative ablation therapy was performed on 19 patients with chronic atrial fibrillation. Mean follow-up is 35.4+/-19.2 months (range 5 to 63). SMV implantation was performed using a conventional (32) or a minimally invasive (19) approach, valve size was 29+/-1.5 mm, cross-clamp duration was 81+/-33 minutes. Atrial rhythm was reestablished in 16 of 19 patients. Five patients required reoperation early in this series, two for paravalvular leakage, two for functional stenosis, and one with underlying rheumatoid disease. Mortality was one perioperative (1.96%, non-valve-related), one after reoperation as a result of multiple organ failure (MOF), and five during late follow-up (30+/-7 months postoperatively) for noncardiac causes. Regular echocardiographic control revealed good SMV function (Vmax 1.7+/-0.2m/s, P(mean) 3.9+/-1.2 mm Hg) and well-preserved ejection fraction postoperatively and at most recent follow-up. CONCLUSIONS: Midterm results after SMV implantation are promising. Preservation of the annuloventricular continuity leads to stable left ventricular function and combined with ablation therapy to physiological hemodynamics. Long-term durability remains to be proven.

Left ventricular reverse remodeling after surgical therapy for aortic stenosis: correlation to Renin-Angiotensin system gene expression.

BACKGROUND: Surgical therapy for aortic stenosis leads to reverse remodeling, with normalization of left ventricular hypertrophy (LVH). The aim of this study was to examine Renin-Angiotensin system (RAS) gene expression in this setting. METHODS: Growing sheep (n=44) underwent supracoronary aortic banding for controlled induction of LVH at the age of 6 to 8 months (A=baseline). Surgical revision to completely release the pressure gradient was performed 8.3+/-1 months later (B). The animals were sacrificed after another 10.1+/-2 months (C). Along with hemodynamic measurements, subtractive hybridization and competitive polymerase chain reaction were applied to quantify mRNA expression for angiotensin-converting enzyme (ACE) and angiotensin receptors 1 and 2 (AT1-R and AT2-R). RESULTS: Left ventricular mass index was 82+/-21 g (A), 150+/-33 g (B), and 78+/-18 g (C), P<0.01. Left ventricular function and cardiac index remained stable. Myocardial fiber diameter was 11.3+/-0.8 (A), 15.9+/-1.2 (B), and 11.4+/-1 (C) microm, P<0.01. Gene expression was as follows: ACE 0.8+/-0.05 (A), 1.3+/-0.08 (B), and 0.9+/-0.06 (C), P<0.01; AT1-R 0.7+/-0.06 (A), 0.9+/-0.07 (B), and 0.3+/-0.04 (C), P<0.01; AT2-R 0.5+/-0.05 (A), 0.2+/-0.04 (B), and 0.5+/-0.05 (C), P<0.01. CONCLUSION: LVH in aortic stenosis coincides with significant alterations of the RAS. Surgical therapy leads to reverse remodeling, which is paralleled by regression of RAS gene expression.

Hemodynamic evaluation of stentless mitral valve replacement.

The purpose of this study was to evaluate the perioperative and postoperative hemodynamic function of recently introduced stentless mitral valves (SMVs). Forty-two selected patients who had received the SMV since 1997 had preoperative, postoperative, and follow-up transthoracic echocardiographic (TTE) examinations. Transesophageal echocardiography (TEE) was applied routinely during the operation as well as postoperatively if indicated. Adequate SMV function was seen in all patients perioperatively. Echocardiographic prediction of valve size and of papillary muscle distances was correct in 37 of 42 patients. Transvalvular blood flow velocities were 1.6 +/- 0.2 m/s postoperatively versus 1.8 +/- 0.3 m/s at 1 year and 1.7 +/- 0.3 m/s at 3-year follow-up. Mean transvalvular gradients were 4.3 +/- 1.6, 3.8 +/- 1.9, and 4.7 +/- 1.1 mm Hg, respectively. TEE and TTE are extremely useful to assist SMV implantation as well as for regular follow-up evaluation. The hemodynamic function after SMV implantation with preservation of the annulo-ventricular continuity is promising.

Experimental evaluation and early clinical results of a new low-profile bileaflet aortic valve.

We performed an experimental and clinical evaluation of a new low-profile bileaflet aortic valve (Regent, St. Jude Medical Inc., St. Paul, MN, U.S.A.). Common valve sizes were experimentally tested for leakage volume, pressure drop, and transvalvular hemodynamics using a pulse duplicator. Thirty patients (mean age 60 +/- 7 years, predominant valve stenosis n = 25) received the Regent prosthesis for initial clinical evaluation. In vitro evaluation revealed equivalent leakage volumes, larger performance indices (0.552 versus 0.513), and lower pressure drops in comparison to SJM hemodynamic plus valve controls. Clinically, 21 mm (n = 9), 23 mm (n = 12), and 25 mm (n = 9) valves were implanted with no significant perioperative complications. Echocardiography revealed low transvalvular flow velocities (2.2 +/- 0.4 m/s) and low pressure gradients (20 +/- 6 mm Hg) postoperatively and at 6 months follow-up. In vitro testing and early clinical results are promising; however, long-term performance has to be proven.