Toward a rational design of surface textures promoting endothelialization

The safe integration of cardiovascular devices requires the sustainable coverage of their luminal surface by endothelial cells (ECs). The engineering of active surface textures has the potential to coordinate cellular adhesion and migration under the action of hemodynamic forces. We define a paradigm to rationally design textures maximizing EC activities as a function of the applied stresses. This is based on harnessing the adhesions established by ECs through fine-tuning of the vertical extend of the underlying surface nanotopography.

On cell separation with topographically engineered surfaces

BACKGROUND

Topographical modifications of the surface influence several cell functions and can be exploited to modulate cellular activities such as adhesion, migration and proliferation. These complex interactions are cell-type specific, therefore engineered substrates featuring patterns of two or more different topographies may be used to obtain the selective separation of different cell lineages. This process has the potential to enhance the performance of biomedical devices promoting, for example, the local coverage with functional tissues while demoting the onset of inflammatory reactions.

FINDINGS & CONCLUSIONS

Here we present a computational tool, based on Monte Carlo simulation, which decouples the contribution of cell proliferation and migration and predicts the cell-separation performance of topographically engineered substrates. Additionally, we propose an optimization procedure to shape the topographically engineered areas of a substrate and obtain maximal cell separation.

Retrospective analysis of outcome data with regards to the use of Phisio®-, Bioline®- or Softline®-coated cardiopulmonary bypass circuits in cardiac surgery

BACKGROUND

Numerous cardiopulmonary bypass circuits with various coatings designed to reduce the inflammatory response and to provide better hemocompatibility are available. The aim of this study was to compare the effect of phosphorylcholine-coated, albumin-heparin-coated and synthetic polymer-coated perfusion tubing systems on patient outcome.

METHODS

We performed a retrospective database review of elective patients between January 1st 2010 and December 31st 2010. Demographics, preoperative, operative, postoperative data and follow-up were collected and statistically analysed.

RESULTS

We identified 201 patients and formed three groups: Group 1 with phosphorylcholine coating (n=133), Group 2 with albumin-heparin coating (n=32) and Group 3 synthetic polymer coating (n=36). Mean age was 68 ± 11 years, additive Euroscore 5.8 ± 2.7. In-hospital outcomes were comparable between the groups without statistically significant differences. The overall 30-day and 1-year late survival were 98.5% and 96.7 ± 1.9%, respectively.

CONCLUSIONS

Our findings suggest that in-hospital and follow-up outcomes are comparable in cardiac surgery patients after using either phosphorylcholine-coated, albumin-heparin-coated or synthetic polymer-coated circuits during cardiopulmonary bypass.

Replacement of the Aortic Valve and Ascending Aorta With an Extended Root Stentless Xenograft

PURPOSE

We present an early series to determine the technical feasibility of simultaneous aortic valve and complete ascending aortic replacement using a longer stentless aortic xenograft, harvested with an extended root.

DESCRIPTION

The stentless xenograft valved conduits commercially available are too short for complete ascending aorta replacement, and usually a prosthetic tube graft is required distally.

EVALUATION

To avoid this extra prosthetic conduit distally a number of stentless aortic xenografts with extended conduit were obtained from a supplier (Medtronic Inc). They were inserted in 6 elderly patients (67.8 +/- 7.1 years) who all required aortic valve and ascending aorta replacements owing to pathologic dilation.

CONCLUSIONS

In all cases an extra prosthetic conduit was avoided, and the length of the available biological conduit comfortably allowed total ascending aortic replacement without tension. The advantages therefore were one less suture line, cost saving regarding the prosthetic conduit, shorter cross-clamping time, and possibly shorter time spent on hemostasis.

Results of a modified left atrial maze procedure as a combined procedure

Starting in November 1999, we performed a left atrial radiofrequency ablation procedure concomitantly to a variety of cardiac surgical procedures. By January 2001, this ablation procedure had been performed on 100 patients (age 65.7 +/- 10.4 years, 53 % male, 47 % female, left atrium 51.0 +/- 7.5 mm) suffering either from chronic or paroxysmal atrial fibrillation. Primary cardiac pathology was mitral valve disease in most cases (43), aortic valve disease (28) or coronary heart disease (27). After bilateral pulmonary veins isolation, an additional ablation line was directed from the left pulmonary veins to the mitral valve annulus (Thermaline probe, Boston Scientific Corporation, USA). Finally, the left atrial appendage was resected. Surgical success was evaluated in the immediate postoperative course, 3 and 6 months postoperatively (ECG and echocardiography), and every year after that. Operative time was 229.7 +/- 56.5 min, ablation time 18.8 +/- 6.9 min. Follow-up is 95 % complete at the time of writing. Mean follow-up time was 7.3 months, ranging from 3 to 23 months. Success (sinus rhythm and atrial contraction) was proven in 72 out of 90 patients (80.0 %) (75.0 % mitral valve surgery, 84.0 % other cardiac surgery). The reported results support a broad spectrum of indications for this left atrial ablation procedure.

Older patients fare better with the Ross operation

BACKGROUND

The Ross operation has an established position in young patients. We address the question of whether any age group profits most from the Ross operation, and we compare the results in various ages.

METHODS

From February 1995 to August 2001 we performed 250 Ross operations. Group 1 consisted of 46 patients, ages 2 to 25 years (median age, 15 years). Group 2 consisted of 123 patients, ages 26 to 49 years (median age, 39 years). Group 3 consisted of 81 patients, ages 50 to 67 years (median age, 55 years). Echocardiography was performed perioperatively, at 2 to 6 months, and then yearly.

RESULTS

Mean follow-up for the three groups was 32, 31, and 28 months, respectively (p = 0.36). One patient from group 2 died after 25 months caused by suppurative pneumonia and 3 patients from group 3 died (1 from suspected acute thoracic aorta dissection at 40 months, 1 from ventricular fibrillation after 25 months, and 1 from an undiagnosed sudden death at 5 months). Autograft replacement was necessary for 3 patients from group 2 and 1 from group 3. Autograft repair was necessary for 1 patient from group 2, and pulmonary homograft reoperation was necessary for 1 patient from group 1. All other autografts currently have physiologic gradients and clinically insignificant regurgitation. Median peak gradient across the right ventricular outflow tract was 23.6 +/- 18 mm Hg for group 1, 14.6 +/- 8 mm Hg for group 2, and 11.5 +/- 7 mm Hg, which was significantly lower for group 3 patients (p < 0.001). Eleven patients are under close follow-up for right ventricular outflow tract gradients > or = 40 mm Hg; eight of these patients are from group 1, 3 are from group 2, and there are none from group 3.

CONCLUSIONS

Although the Ross operation provides excellent results in all age groups, the problem of right ventricular outflow tract stenosis has not been seen in patients older than 50 years, which implies that it offers superior results for aortic valve disease in middle aged and older patients.

Surgical pacemaker lead extraction: 10 years of experience

Due to the worldwide increasing number of patients with pacemaker implants, the problem of lead extraction with its potential difficulties and complications has gained enormous importance. Primarily lead extraction should be attempted percutaneously; however, in case of failure or contraindications for percutaneous extraction, such as vegetations with a high risk of embolization (size >10mm), a surgical approach is necessary.    From 1991 until 2001 we performed surgical lead extraction in 16 patients (mean age 62.1±15.0 years, male 13, female 3). All patients presented with lead infection and clinical symptoms of septicemia at a rather advanced stage, in average 7.0±8.8 months after the onset of symptoms. In 13 cases we performed an open heart approach with the use of cardiopulmonary bypass, in 3 a closed heart approach. Perioperative mortality was 0%. Pacemaker leads were successfully removed in 100%. No reinfections were reported.    Surgical pacemaker lead extraction is a highly effective tool and can be safely performed without significant mortality. If surgery is indicated it should be performed as early as possible.

The Ross operation as a combined procedure and in complicated cases--is there an increased risk?

BACKGROUND

In this report we address the question whether the Ross operation can be recommended in combined and complicated cardiac procedures.

METHODS

From February 1995 to July 2000, we performed 203 Ross operations, 129 with ideal clinical presentation (group 1: mean age 41 +/- 13 years, male 105). In 74 patients, the clinical presentation was complex (group 2: mean age 35 +/- 17 years, male 57), defined as previous aortic or cardiac operations in 32, active endocarditis in 8 or combined procedures in 40 patients. Follow-up is 95 % complete.

RESULTS

Neither early mortality nor thromboembolic events were observed. Complications in group 1 vs. group 2 were prolonged ventilation in 1 vs. 1, pacemaker insertion in 1 vs. 2, minor myocardial infarction in none vs. 2 and postoperative bleeds in 2 vs. 3 patients. In group 1, one patient died of hemoptysis at 25 months, and in group 2 one sudden death occurred at 5 months. In the long term, two patients required reoperation for autograft failure in group 1, and one on group 2. Pulmonary stenosis required surgical treatment in one patient of group 2. Echocardiography revealed physiological gradients across the autograft with no significant regurgitation in either group.

CONCLUSION

The Ross operation has excellent mid-term results and is a safe and attractive therapeutic approach, both in combined procedures and complex clinical presentations.

[Moral status of the embryo]

Diagnosis for the purposes of embryo selection prior to implantation, research using embryos and the German embryo Protection Act (1991) constitute the starting-point for a discussion of the legal and moral status of embryos. Since the entire genetic programme for a future human being is established at the point of completed union of female egg-cell and male sperm-cell, the embryo conceived in vitro also benefits from the protection of human dignity. It may therefore not be treated exclusively as an object of another's purposes, in other words, it may not be exploited for research or rejected after pre-implantation diagnosis. This conclusion is in accordance with constitutional case-law and international human rights treaties. Research using embryos is permissible in the case of one narrowly circumscribed exception, which will be more closely defined.

Background and early results of a modified left atrial radiofrequency procedure concomitant with cardiac surgery

With the introduction of the maze operation Cox was able to show that the surgical treatment of atrial fibrillation (AF) is feasible. However, the maze operation remains surgically demanding and time-consuming as it requires multiple incisions in both atria. This has led to the development of various modifications. With new ablative technology and the acceptable results of an exclusively left atrial maze procedure in combination with mitral valve surgery, it has become possible to simplify the maze operation radically. Thirty-one patients ( mean age 62.3 years) with chronic or intermittent AF underwent a modified radiofrequency procedure in combination with some other cardiac surgical operation. Mitral valve disease coexisted in 17 patients, aortic valve disease in 9, coronary heart disease in 4 patients and 1 had an atrial septal defect (ASD). After left atriotomy and with the use of the Thermaline radiofrequency ablator probe, bilateral pulmonary vein isolation was carried out. An additional ablation line was directed from the left pulmonary veins to the posterior mitral valve annulus, and finally the left atrial appendage was resected. The complete procedure added an average of only 18.2 minutes to the operation. In the early postoperative course AF or atrial flutter recurred in 12 patients but at discharge only 8 patients (24%) still had an arrhythmia. We concentrated on the first 26 patients of our series who had received a follow-up examination 3 months postoperatively. At discharge 18 of the 26 patients were in sinus rhythm (69,2%), and at 3 months after surgery 23 of 26 patients were in sinus rhythm (88.5%), with recovery of atrial contraction confirmed echocardiographically. Only 4 patients still required medication for arrhythmias. The modified radiofrequency ablation procedure of the left atrium proved to be simple to perform, quick and reliable. It offers the possibility of a surgical cure for AF when performed together with another cardiac operation, and the early results indicate a high rate of success for this simple procedure.

DNA damage in human leukocytes after ischemia/reperfusion injury

Leukocytes have been shown to play an important role in the development of tissue injury after ischemia and reperfusion (I/R). In the present study, the effects of tourniquet-ischemia on induction of DNA damage in peripheral leukocytes and on respiratory burst of neutrophils in humans were examined. The DNA damage was measured as increased migration of DNA using the single-cell gel-electrophoresis technique (comet assay). Intracellular production of reactive oxygen species by neutrophils was measured flow-cytometrically using dihydrorhodamine 123 as indicator. Postischemic, significantly increased migration of DNA was found in leukocytes of 20 patients (tourniquet-ischemia of the lower limb for 65-130 min, anterior-cruciate-ligament-reconstruction) and in 10 experiments (1 volunteer, repeated tourniquet-ischemia of the upper limb for 60 min, no operation). DNA effects were most pronounced 5-30 min after tourniquet release, and then declined over a 2 h period, but did not return to preischemic baseline values. A similar time course showed the oxidative status of unstimulated granulocytes during reperfusion. Simultaneously, opposing changes were measured in formyl peptide (f-MLP)- or phorbol ester (PMA)-stimulated granulocytes, which showed a significantly declined respiratory burst reaction after tourniquet-release indicating preactivation of neutrophils by IR. Our data suggest that IR induces genotoxic effects in human leukocytes presumably in response to oxidative stress during reperfusion.