Perioperative neuromonitoring during thoracoabdominal aortic aneurysm open repair: A systematic review

OBJECTIVES

While open surgical repair remains the gold standard for thoracoabdominal aortic aneurysm (TAAA) treatment, there is still no consensus regarding perioperative neuromonitoring technique for prevention of spinal cord ischaemia (SCI).

METHODS

In this systematic review, we aimed to explore the effects and practices of neuromonitoring during the open TAAA repair. A systematic literature search in PubMed, Embase via Ovid, Cochrane library and ClinicalTrialsGov until December 2022 was performed.

RESULTS

A total of 535 studies were identified from the literature search, of which 27 studies including a total of 3130 patients met the eligibility criteria. Most studies (21 out of 27, 78%) investigated the feasibility of motor evoked potentials (MEP), while 15 analysed somatosensory evoked potentials (SSEP) and 2 studies analysed near-infrared spectroscopy (NIRS) during open TAAA repair.

CONCLUSIONS

Current literature suggest that rates of postoperative SCI can be kept at low levels after open TAAA repair with the adequate precautions and perioperative manoeuvres. Neuromonitoring with MEP provides the surgeon objective criteria to direct selective intercostal reconstruction or other protective anaesthetic and surgical manoeuvres. Simultaneous monitoring of MEP and SSEP is a reliable method that can rapidly detect important findings and direct adequate protective manoeuvres during open TAAA repair.

Factors associated with long-term outcomes in adult congenital heart disease patients with infective endocarditis: A 16-year tertiary single-centre experience

OBJECTIVES

Studies concerning factors associated with long-term outcomes in adult congenital heart disease patients after infective endocarditis are scarce, while infective endocarditis-related mortality in these patients remains a burden. We evaluated the factors associated with long-term survival in adult congenital heart disease patients admitted for infective endocarditis.

METHODS

We performed a retrospective single-centre study of all adult congenital heart disease patients admitted for infective endocarditis to a tertiary cardiothoracic centre between 1999 and 2015. Underlying adult congenital heart disease, detailed echocardiographic and clinical data, surgical treatment and long-term follow-up were analysed.

RESULTS

We identified 151 adult congenital heart disease patients admitted due to 176 episodes infective endocarditis with 30-day, 6-month, 1-, 5- and 10-year survival of 95.4%, 92.7%, 92.7%, 84.7% and 75.6%, respectively. In a multivariable analysis, adjusted estimated probability of death was consistently higher after an infective endocarditis episode among patients with complex as compared to simple/moderate adult congenital heart disease: 10.6% vs. 2.4% at 30 days, 15.0% vs. 3.4% at 6 months and 1 year, 30.4% vs. 7.8% at 5 years, and 44.9% vs. 13.1% at 10 years. Risk of death was higher among patients with prosthetic valve in comparison with those without (RR 1.73-1.92). Surgical treatment was required in 76 (43.2%) episodes with 30-day mortality of 3.9%. Risk of death appeared to be lower than in the conservatively treated subgroup (RR 0.71-0.78).

CONCLUSIONS

We demonstrated satisfactory long-term survival in adult congenital heart disease patients who were treated for infective endocarditis in a tertiary cardiothoracic centre. Early mortality tended to be lower in the surgically treated subgroup. Factors negatively associated with long-term survival were complex adult congenital heart disease and presence of prosthetic valve.

Comparing mid-term outcomes of Cox-Maze procedure and pulmonary vein isolation for atrial fibrillation after concomitant mitral valve surgery: A systematic review

BACKGROUND

Although concomitant pulmonary vein isolation (PVI) is used more frequently than the Cox-Maze procedure, which is currently the gold standard treatment for atrial fibrillation (AF), data on the comparative effectiveness of the two procedures after concomitant mitral valve (MV) surgery are still limited.

OBJECTIVE

We conducted a systematic review to identify randomized controlled trials (RCTs) and observational studies comparing the mid-term mortality and recurrence of AF after concomitant Cox-Maze and PVI in patients with AF undergoing MV surgery based on 12-month follow-up.

METHODS

Medline, EMBASE databases, and the Cochrane Library were searched from 1987 up to March 2022 for studies comparing concomitant Cox-Maze and PVI. Additionally, a meta-analysis of RCTs was performed to compare the mid-term clinical outcomes between these two surgical ablation techniques.

RESULTS

Three RCTs and three observational studies meeting the inclusion criteria were included in this systematic review with 790 patients in total (532 concomitant Cox-Maze and 258 PVI during MV surgery). Most studies reported that the concomitant Cox-Maze procedure was associated with higher freedom from AF at 12-month follow-up than PVI. Regarding AF recurrence, estimates pooled across the three RCTs indicated large heterogeneity and high uncertainty. In the largest and highest quality RCT, 12-month AF recurrence was higher in the PVI arm (risk ratio = 1.58, 95% CI: 0.91-2.73). In two out of three higher-quality observational studies, 12-month AF recurrence was higher in PVI than in the Cox-Maze arm (estimated adjusted probabilities 11% vs. 8% and 35% vs. 17%, respectively). RCTs demonstrated comparable 12-month mortality between concomitant Cox-Maze and PVI, while observational studies demonstrated the survival benefit of Cox-Maze.

CONCLUSIONS

Concomitant Cox-Maze in AF patients undergoing MV surgery is associated with better mid-term freedom from AF when compared to PVI with comparable mid-term survival. Large observational studies suggest that there might be a mid-term survival benefit among patients after concomitant Cox-Maze. Further large RCTs with longer standardized follow-up are required to clarify the benefits of concomitant Cox-Maze in AF patients during MV surgery.

Fiftieth anniversary of the first heart transplantation in Switzerland in the context of the worldwide history of heart transplantation

On 3 December 1967, Christiaan Barnard performed the first heart transplantation in the world at Groote Schuur Hospital in Cape Town, South Africa. In the succeeding months, heart transplantations in the USA, Asia and Europe followed. On 14 April 1969, Åke Senning successfully accomplished the first heart transplantation in Switzerland at the former Cantonal Hospital in Zurich. In the summer of 1969, he undertook a second heart transplantation. Although the surgical procedure went well technically, both patients died within weeks to months after transplantation. Causes of death were infection in the first and rejection in the second patient. Senning’s colleagues around the world had similar experiences. Survival after heart transplantation was unacceptably low. The heart transplant community recognised the lack of knowledge about immunological processes and appropriate immunosuppressive regimens as underlying reason for the early deaths. Most transplant centres decided to refrain from heart transplantation until sufficient immunological insight became available. After the introduction of the new immunosuppressive drug ciclosporin into the clinic and the availability of tools to monitor rejection in the early 1980s, heart transplant programmes were restarted all over the world. The legal recognition of brain death allowed procurement of donor hearts without exposure to warm ischaemia, and the principle of cold storage enabled prolongation of ischaemia time and acceptance of donors in distant hospitals, resulting in enlargement of the donor pool. In Switzerland, Marko Turina resumed heart transplantation in 1985 at Senning’s former workplace in Zurich. The number of heart transplants in Switzerland and in the world grew rapidly because the outcome markedly improved. Particularly over the long-term, survival in Zurich surpassed the outcome worldwide. Zurich created internationally recognised milestones such as transplantation of patients with grown-up congenital heart disease, the implementation of the bicaval instead of the right atrial anastomosis during the transplant procedure and the dual transplantation of one heart. Since the middle of the 1990s, however, the number of heart transplants has plateaued, mainly because of donor shortage. The current era is characterised by efforts to increase the number of donors. The utilisation of marginal donors, the change from informed to presumed consent for organ donation and donation after cardiocirculatory-determined death have been proposed to augment the donor pool.

Use of an intravascular gas exchanger: is low systemic heparinization safe?

Extracorporeal membrane oxygenation (ECMO) is a cumbersome procedure. Alternatively, mechanical lung assist can be realized with an intravascular gas exchanger (IVOX). To assess the degree of initial anticoagulation required during intravascular lung assist, we evaluated two regimens of systemic heparinization in 10 bovine experiments. The animals were randomly assigned to two groups with either full systemic heparinization (heparin loading dose 300 IU/kg bodyweight; activated coagulation time (ACT) > 480 s) or low systemic heparinization (heparin loading dose 100 IU/kg bodyweight; ACT > 180 s). The surface heparinized intravascular gas exchanger was placed in the caval axis under fluoroscopic control, and a standard battery of blood samples was drawn before and at regular intervals during the procedure. After six hours of intravascular lung assist the device was explanted, drained, weighed, and carefully analysed. Preassist haematocrit was 25 ± 5% for full versus 24 ± 7% for low (NS) as compared with 23 ± 8% for full versus 26 ± 3% for low (NS) postassist. Platelet levels were 100 ± 25 for full versus 100 ± 21 % for low (NS) preassist as compared with 64 ± 22% for full versus 78 ± 22% for low (NS) postassist. Mean ACT was 157 ± 12 s for full versus 158 ± 18 for low (NS) preassist as compared with 800 ± 244 s versus 219 ± 25 for low (p < 0.05) postassist. Thrombin time was 20 ± 2 s for full versus 23 ± 2 s for low (NS) as compared with > 200 s for both groups after assist. Relative fibrinopeptide A levels were 7.3 ± 1.1 ng/ml for full versus 6.3 ± 1.6 ng/ml for low (NS) preassist as compared with 4.7 ± 4.1 ng/ml for full versus 5.8 ± 0.9 ng/ml for low (NS) postassist. CO2 transfer was 40 ± 10 ml/min for full versus 36 ± 10 ml/min for low (NS) at the begining as compared with 45 ± 25 ml/min for full versus 46 ± 15 for low (NS) at the end. Weight increase due to device deposits (clots) was 14 ± 11 g for full versus 13 ± 10 g for low systemic heparinization (NS). Intravascular lung assist with low versus full systemic heparinization appeared to result in similar activation of the coagulation system, device deposits and gas transfer rates. Considering our clinical experience we can say that application of the device with reduced systemic heparinization is useful in selected patients.

Blood supply of the sternum and its importance in internal thoracic artery harvesting

BACKGROUND

The internal thoracic artery (ITA) is the conduit of choice in coronary bypass grafting, due to the excellent long-term results achieved using it. However, increased incidence of sternal infections after pedicled ITA harvesting has revived interest in the morphology of sternal blood supply. Our aim was to discuss the topography of the sternal branches with emphasis on internal thoracic artery harvesting.

METHODS

This study was conducted on 50 fresh specimens of the anterior thorax wall. Radio-opaque material was injected and angiograms of the ITA were performed. Subsequently, the specimens were preserved and a dry dissection of each ITA and its branches was carried out.

RESULTS

In dry dissected specimens, four types of vessels were identified that have the potential to carry blood to the sternum after harvesting the ITA. In the first group, the artery to the sternum also supplies the intercostal space. In the second morphologic variant, the sternal branch gives off the perforating and anterior intercostal arteries. In the third group, we classified the common branch of the sternal and perforating arteries. In the fourth group, the sternal artery originated from the ITA as an independent branch.

CONCLUSIONS

For sternal-intercostal, perforating-intercostal, and sternal-perforating branches to function as collaterals after ITA harvesting, the common trunk of origin must remain intact. Based on morphologic data, we recommend ligating the common trunk as close as possible to the ITA; in this way, collateral blood flow to the sternum remains intact.

Annulus Fibrosus of the Mitral Valve: Reality or Myth

INTRODUCTION

Surgical repair of the mitral valve is in most cases limited to the posterior leaflet of the mitral valve and to the annulus fibrosus. The term annulus fibrosus is still used in anatomical and clinical terminology and is described as a cord like structure providing the attachment of the mitral vale. However, to date no evidence exists of a ring-or cord-like structure at this area. Herein, we describe the attachment of the mitral valve by using the macroscopical and microscopical techniques.

MATERIAL AND METHODS

The ventricular attachment of the posterior mitral valve leaflet was investigated in 10 human hearts. In dry dissected specimens, the intraventricular illumination was used to identify the attachment of the mitral valve to the left ventricular muscle. Using the histological techniques, we verified the position of the annulus fibrosus.

RESULTS

The attachment of the posterior mitral valve leaflet is a band-like structure positioned between the left ventricular muscle and the left atrium. This fibrous band illustrates the morphological attachment of the mitral valve and, as thus, was interpreted as the annulus fibrosus of the mitral valve.

CONCLUSION

Based on our data, no ring-like structure was found corresponding to the anatomical description of the annulus fibrosus, instead the band-like fibrous tissue was identified positioned between the mitral valve and the left ventricle. Histologicaly, we detected that this structure is part of the greater structural system that is directly connected to the membranous septum, to the left and right fibrous trigone and the attachment aortic root to the left ventricular muscle.

Geometric models of the aortic and pulmonary roots: suggestions for the Ross procedure

OBJECTIVE

To discuss geometric factors, which may influence long-term results relating to homograft competence following the Ross procedure, we describe the 3D morphology of the pulmonary and aortic roots.

MATERIALS

Measurements were made on 25 human aortic and pulmonary roots. Inter-commissural distances and the heights of the sinuses were measured. For geometrical reconstruction the three commissures and their vertical projections at the root base were used as reference points.

RESULTS

In the pulmonary root, the three inter-commissural distances were of similar dimensions (17.9+/-1.6mm, 17.5+/-1.4mm and 18.6+/-1.5mm). In the aortic root, the right inter-commissural distance was greatest (18.8+/-1.9mm), followed by the non-coronary (17.4+/-2.0mm) and left coronary sinus commissures (15.2+/-1.9mm). The mean height of the left pulmonary sinus was greatest (20+/-1.7mm) followed by the anterior (17.5+/-1.4mm) and right pulmonary sinus (18+/-1.66mm). In the aortic root, the height of the right coronary sinus was the greatest (19.4+/-1.9mm) followed by the heights of the non-coronary (17.7+/-1.8mm) and left coronary sinus (17.4+/-1.4mm). Measured differences between parameters determine the tilt angle and direction of the root vector. The tilt angle in the pulmonary root averaged 16.26 degrees , respectively; for the aortic roots, it was 5.47 degrees .

CONCLUSIONS

Herein we suggest that the left pulmonary sinus is best implanted in the position of the right coronary sinus, the anterior pulmonary in the position of the non-coronary sinus and the right pulmonary sinus in the position of the left coronary sinus. In this way, the direction of the pulmonary root vector will be parallel to that of the aortic root vector.

Clinical anatomy of the atrioventricular node artery

BACKGROUND AND AIM OF THE STUDY

The study aim was to describe the topographical relationship of the atrioventricular (AV) node artery and mitral valve annulus fibrosus with regard to AV node dysfunction following mitral valve replacement or ring annuloplasty.

METHODS

The anatomy of the AV node artery was analyzed in 55 human hearts without previous pathological alterations. Selective coronary angiograms were performed to identify the AV node origin. Run-off of the AV node artery and its topographical relationship to the mitral valve attachment was analyzed in dry-dissected hearts. The position of the AV node was verified by histological sectioning.

RESULTS

The AV node artery originated from the right coronary artery in 73% of examined cases, and from the left coronary artery in 27% of cases. The left AV node artery was closely related to the mitral valve attachment, especially at the area of the left proximal part of the posterior leaflet.

CONCLUSION

These morphological data were compared to clinical reports emphasizing the postoperative incidence of AV block after mitral valve implantation and ring annuloplasty. The occurrence of early postoperative AV node block ranged from 20% to 37%. By comparing the present data with available literature, it can be stated that there is a high risk of intraoperative damage to the left AV node artery during manipulation of the mitral valve annulus fibrosus.

Respiratory dependent compression of a venous bypass: therapy by stenting

Although coronary artery bypass surgery has provided major advances in the treatment of coronary artery disease, narrowing of bypass vessels still constitutes a drawback of this therapy. Although this event is most frequently caused by intraluminal processes, obstruction from external structures is extremely rare. We report such a case in which external bypass compression was provoked by deep inspiration causing typical anginal symptoms. Percutaneous coronary intervention including stent placement provided bypass patency independent from the patient's respiratory phase. Disappearance of symptoms and absence of myocardial ischemia in perfusion scans confirmed successful treatment.

Aortic Dissection With Potential Origin From a Mechanical Bypass Anastomosis

Ascending aortic dissection is a known complication of cardiac surgery. Off-pump coronary artery bypass surgery seems to be associated with a higher risk for this event as compared with on-pump bypass surgery. This increased risk may result from aortic side-clamping under pulsatile flow as opposed to continuous flow in conventional bypass surgery. Mechanical devices allowing performance of proximal bypass anastomoses without aortic side-clamping are supposed to reduce the risk for aortic dissection. We report a case in which ascending aortic dissection occurred 8 days after off-pump bypass surgery, most likely arising from a mechanically performed proximal bypass anastomosis.

Normalization of high pulmonary vascular resistance with LVAD support in heart transplantation candidates

OBJECTIVE

Pulmonary hypertension (PH) and elevated pulmonary vascular resistance (PVR) lead to poor outcome after heart transplantation due to postoperative failure of the non-conditioned right ventricle. The role of continuous flow left ventricular assist device (LVAD) support in the reduction of elevated PVR was evaluated in a series of clinical implants.

METHODS

Among 17 patients with terminal heart failure receiving a MicroMed DeBakey LVAD as bridge to transplant, there were six patients with pulmonary hypertension (mean systolic PAP 47 mmHg) and high PVR (398 dynes/cm5), previously not considered suitable for heart transplantation, who underwent serial right heart catheters during their LVAD support period.

RESULTS

In these patients mean systolic pulmonary pressure dropped to 29 mmHg and PVR decreased to a mean 167 dynes/cm5 under LVAD support. Clinical improvement was significant in all patients. Four patients were successfully transplanted without major postoperative difficulties (mean duration 130 days support) and all are doing well to date. Post-transplant-PVR remained in the normal range in all transplanted patients.

CONCLUSIONS

Elevated PVR and severe PH were both previously considered as contraindication for heart transplantation. A period of LVAD pumping leads to a progressive decrease of PVR and normalization of pulmonary pressures, making these patients amenable for heart transplantation. LVAD as bridge to heart transplantation is safe and highly beneficial for terminal heart failure patients with severe PH.

In the Footsteps of Senning: Lessons Learned From Atrial Repair of Transposition of the Great Arteries

The Senning operation has evolved from being the initial surgical correction that allowed survival in complete transposition of the great arteries to an integral part of the anatomic repair of congenitally corrected transposition. In patients with complete transposition, the Senning operation has given satisfactory initial and long-term surgical results, but the potential for right ventricular failure and atrial arrhythmias have drastically reduced its indications in the current era. The long-term follow-up and pertinent postoperative issues of the Senning operation will be reviewed, along with its newfound role in the anatomic repair of congenitally corrected transposition.

A new classification of the mitral papillary muscle

BACKGROUND

Mitral valve homograft implantation and reconstruction of the left ventricular subvalvular apparatus requires a good knowledge of the morphology of the left papillary muscles. A comprehensive description of the left ventricular subvalvular apparatus is presented to aid in this procedure and to support conventional and endoscope-assisted reconstruction of the chordae tendineae.

MATERIAL/METHODS

The subvalvular apparatuses of 100 unfixed human hearts were investigated. Papillary muscles were endoscopically examined on the hearts in situ, then the hearts were explanted and the subvalvular apparatus was macroscopically inspected. The geometrical arrangement of the chordae tendineae was determined.

RESULTS

We defined three groups of the left ventricular papillary muscle. In group I the basal part and the apex of the muscle were undivided. In group II there were two heads; in subgroup II/A the base of the papillary muscle was undivided and in II/B it was divided into two separate parts. In group III the papillary muscle had three heads. In subgroup III/A the base was undivided, while in III/B it was made up of two and in III/C three separate parts.

CONCLUSIONS

We propose a classification of the left ventricular subvalvular apparatus based on the macroscopic and endoscopic investigations. It emphasizes the morphology of the apical and basal parts of papillary muscles and includes the geometrical arrangement of the chordae tendineae. Thus it may be of a great value in endoscopic and conventional mitral valve replacement or reconstruction of the chordae tendineae and in mitral valve homograft implantation.

Inferior Partial Sternotomy for Surgical Closure of Isolated Ventricular Septal Defects in Children

BACKGROUND

Surgical closure of isolated ventricular septal defect (VSD) through partial inferior sternotomy offers the advantages of a much shorter, cosmetically superior skin incision, potentially improved sternal stability, a lower rate of infection, and less postoperative pain. We report our technique and results of use of inferior partial sternotomy for closure of isolated VSD in children.

PATIENTS AND METHODS

From July 2002 to July 2003, 24 consecutive patients with a median age of 4.5 months (range, 1 month-4.5 years) underwent partial inferior sternotomy for isolated VSD closure. The length of the incision ranged from 4 to 6 cm. Special features of the approach included T incision of the lower sternum (from the fourth intercostal space to the xiphoid), establishment of cardiopulmonary bypass with central cannulation, aortic cross-clamping, and cardioplegic arrest. All VSDs were approached through right atriotomy. Perimembranous VSDs were exposed after detachment of the anterior leaflet of the tricuspid valve and were closed with a continuous suture. Muscular VSDs were approached directly. Perioperative and postoperative echocardiographic findings were available for all patients. Follow-up was complete.

RESULTS

There was no mortality or significant surgical morbidity. Median cross-clamping and cardiopulmonary bypass times were 43 and 103 minutes, respectively. All patients were in sinus rhythm. Perioperative and postoperative echocardiography confirmed the absence of any residual defects in perimembranous VSDs and the presence of a trace residual VSD in 4 patients with muscular VSDs. Optimal healing of the partial sternotomy was obtained in all patients.

CONCLUSIONS

Inferior partial sternotomy is less invasive than and cosmetically superior to full sternotomy. It provides excellent results when applied to isolated VSD with standard surgical techniques.

Advantages of subclavian artery perfusion for repair of acute type A dissection*1

OBJECTIVE

Arterial perfusion through the right subclavian artery is proposed to avoid intraoperative malperfusion during repair of acute type A dissection. This study evaluated the clinical and neurological outcome of patients undergoing surgery of acute aortic type A dissection following subclavian arterial cannulation compared to femoral artery approach.

METHODS

From 1/97 to 1/03, 122 consecutive patients underwent surgery for acute type A aortic dissection. Subclavian cannulation was performed in 62 versus femoral cannulation in 60 patients. Clinical characteristics in both groups were similar. Mean age was 61 years (SD+/-14 years, 72% male) and mean follow-up was 3 years (+/-2 years). Patient outcome was assessed as the prevalence of clinical complications, especially neurological deficits, mortality at 30 days, perioperative morbidity and time of body temperature cooling and analyzed by nominal logistic regression analysis for odds ratio calculation.

RESULTS

Arterial subclavian cannulation was successfully performed without any occurrence of malperfusion in all cases. Patients undergoing subclavian cannulation showed an odds ratio of 1.98 (95% CI 1.15-3.51; P=0.0057) for an improved neurological outcome compared to patients undergoing femoral cannulation. Re-exploration rate for postoperative bleeding was significantly reduced in the subclavian group (P<0.0001), as well as occurrence of myocardial infarction (P<0.0001) and duration for body temperature cooling (P=0.004). The 30-day mortality of patients with femoral cannulation was significantly higher compared to patients with subclavian artery cannulation (24 versus 8%; P=0.0179).

CONCLUSIONS

Arterial perfusion through the right subclavian artery provides an excellent approach for repair of acute type A dissection with optimized arterial perfusion body perfusion and allows for antegrade cerebral perfusion during circulatory arrest. The technique is safe and results in a significantly improved clinical and especially neurological outcome.

Left ventricular assist device (LVAD) enables survival during 7 h of sustained ventricular fibrillation

We describe the case of a patient implanted with a DeBakey left ventricular assist device (LVAD) as bridge to transplant who survived 7 h of ventricular fibrillation. He was successfully converted into a stable sinus rhythm.

Anatomic reconstruction of recurrent aortic arch obstruction in children1

OBJECTIVE

Anatomical reconstruction of the aortic arch following aortic arch surgery is challenging. The placement of an extra-anatomical aortic bypass has been proposed for these difficult cases. This approach is not ideal in children due to possible long-term complications. This study presents the results of our policy to reconstruct the aortic arch in recurrent obstruction in children, which are not amenable to balloon dilatation.

METHODS

Seven children with a median age of 8 years (range 1 month-15 years) were operated for aortic arch obstruction following correction of an aortic coarctation. Six children presented another intra-cardial lesion (2 subaortic membranes; 2 VSDs, 1 ostium stenosis of the left main coronary artery, and 1 mitral valve insufficiency). The surgical approach involved a sternotomy, cardiopulmonary support using two arterial inflow cannulas (one above and one below the aortic arch), and moderate hypothermia. Enlargement of the aortic arch was performed by a sliding plasty in four patients and by a patch plasty in three patients. Associated cardiac defects were corrected as well.

RESULTS

It was technically possible to perform the planned operation in all patients. All patients survived and none presented significant postoperative complications. There were no residual gradients in six patients and a gradient of 10 mmHg in one patient postoperatively. One patient showed transient recurrent nerve palsy which recovered within 6 weeks. Follow-up echocardiographic and MRI studies revealed a normal appearing aortic arch with laminar flow.

CONCLUSIONS

Although more demanding, an anatomical reconstruction of the aortic arch can be performed in infants and children with recurrent obstruction of the aortic arch with excellent initial results. This approach may prove superior to an extra-anatomic bypass in the long-term.

Direct closure of the septum primum in atrioventricular canal defects

OBJECTIVE

The objective of this study was to assess the safety of directly closing the septum primum during the correction of atrioventricular canal defects.

METHODS

We performed a retrospective analysis of our experience with direct closure of the septum primum during the repair of atrioventricular canal defect. The series consisted of 28 consecutive patients presenting with a partial (15 patients) and complete (13 patients) atrioventricular canal defect. The cleft in the atrioventricular valve was closed completely in 25 patients and partially in 3 patients (those with a small left lateral leaflet). In complete atrioventricular canal, the ventricular septum defect was closed with a patch of polytetrafluoroethylene (Gore-Tex, W. L. Gore & Associates, Inc, Flagstaff, Ariz) or xenopericardium. Follow-up was complete and ranged from 3 to 21 months (median 11 months).

RESULTS

There were no early or late deaths and no surgical complications. The septum primum defect was closed completely in all patients as assessed by echocardiography. All the patients were in sinus rhythmus, and none had even a temporary complete atrioventricular block. The surgical result and heart rhythm have remained stable over time.

CONCLUSIONS

Direct closure of the septum primum is an easy, quick, and safe procedure during repair of atrioventricular defects.

Early bypass occlusion after deployment of nitinol connector devices

BACKGROUND

Reducing the negative side effects associated with extracorporeal circulation is the major advantage of off-pump revascularization. However, side clamping of a calcified aorta for proximal anastomoses can cause emboli, resulting in neurologic damage. This problem has been addressed by introducing a mechanical anastomosis device (Symmetry, St Jude Medical) that allows vein-to-aorta anastomosis without manipulating the aorta. This report describes our experience with this device.

METHODS

Between June 2001 and April 2002, 77 connectors (1.3 per patient) were deployed in 61 patients (51 men and 10 women; mean age, 68 +/- 8.6 years) undergoing off-pump coronary artery bypass grafting or beating-heart revascularization. Intraoperative quality assessment included transit-time flow measurement (Medistim) and indocyanine green-based angiography (Spy, Novadaq).

RESULTS

The surgeons were meticulously trained in loading of the device. No postoperative neurologic deficits were detected. Fifty-three patients had an uneventful course. However, 8 (13.1%) patients with 12 implanted connectors were symptomatic within 8 months (1 day to 8 months). Angiography revealed significant (95%) stenosis or even occlusion of the proximal vein-to-aorta anastomosis at the level of all connectors. Four patients underwent reoperation (2 dilated-stented and 2 treated with drugs).

CONCLUSION

On the basis of these observations, the routine use of the connector was halted at our institution. At the moment, the use of this therapy is reserved for patients with severely calcified aortas with no technical alternative. Further investigations appear necessary to evaluate the clinical patterns of this otherwise promising technology.

Overlapping annuloplasty of the mitral valve in children

Harmonious reduction of the posterior annulus of the mitral valve can be a useful adjunct to obtain complete valve competence in case of annular dilatation. We present a technique with the use of two resorbable sutures that overlap over the middle third of the posterior annulus that was used in 10 children with good short-term results. Resorption of the sutures should permit subsequent normal growth of the mitral valve. If the primary cause of valvular regurgitation was corrected, it can be expected that the repair will remain stable after resorption of the sutures.

Review article: Tissue engineering of semilunar heart valves: current status and future developments

Heart valve replacement represents the most common surgical therapy for end-stage valvular heart diseases. One major drawback that all heart valve replacements have in common is the lack of growth, repair, and remodeling capability once implanted into the body. The emerging field of tissue engineering is focusing on the in-vitro generation of functional, living semilunar heart valve replacements. This review presents a state-of-the-art overview of the physiological and biomechanical requirements of semilunar heart valves, focusing on the aortic valve. Moreover, recent heart valve tissue engineering is summarized and future options and improvements on the way towards clinical applications are discussed.

Intractable ventricular tachycardia and bridging to heart transplantation with a non-pulsatile flow assist device in a patient with isolated left-ventricular non-compaction

Intractable ventricular tachycardia was investigated in a 51-year-old man with isolated left ventricular non-compaction during implantation of an automated internal cardioverter-defibrillator. Favorable bridging to cardiac transplantation was achieved with the DeBakey left ventricular assist device (LVAD).

The clinical anatomy of the sinus node artery

BACKGROUND

Our basic aim was to describe the topographic relation between the sinus node artery and the superior posterior border of the interatrial septum with regard to the sinus node dysfunction that follows the superior transseptal approach to the mitral valve.

METHODS

During our study 50 human hearts without previous pathologic alterations were analyzed. The position of the sinus node and the course of the sinus node artery were investigated. For identification of the origin of the artery, selective coronary angiograms were performed. The course of sinus node artery and its topographic relation to the interatrial septum was identified by the dry dissections of the hearts. Based on histologic and dry dissected specimens the exact position of the sinus node was determined.

RESULTS

We found that the sinus node artery originates from the right coronary artery in 66% of examined cases and from the left coronary artery in 34% of cases. The sinus node artery crosses the superior posterior border of the interatrial septum in 54% of cases.

CONCLUSIONS

Our results were compared with clinical studies focusing the incidence of the sinus rhythm disturbance after the superior transseptal approach. The incidence of rhythm disturbance varies from 52% to 60% of cases. Comparing our morphologic and clinical results we can state that the risk for intraoperative damage to the sinus node artery during the superior transseptal approach to the mitral valve is high.

Hypoxia and reoxygenation do not upregulate adhesion molecules and natural killer cell adhesion on human endothelial cells in vitro

OBJECTIVES

Ischemia/reperfusion injury is characterized by endothelial cell activation leading to increased expression of adhesion molecules such as inter-cellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, endothelial- and platelet-selectin (E- and P-selectin), and to the subsequent recruitment of leukocytes. The aim of the present study was to investigate the respective effects of a proinflammatory cytokine (tumor necrosis factor alpha, TNF-alpha), hypoxia and/or reoxygenation on adhesion molecule expression and natural killer (NK) cell adhesion in an in vitro model of I/R.

METHODS

Human aortic endothelial cells (HAEC) were stimulated in vitro for 8h with TNF-alpha (1000 U/ml) and exposed to hypoxia (1% O(2)), reoxygenation (21% O(2)) or different combinations thereof. Cell surface expression of ICAM-1, VCAM-1 and E-/P-selectin on HAEC was analyzed by flow cytometry, and culture supernatants were tested for soluble adhesion molecules by ELISA. Rolling adhesion of NK cells on HAEC was determined using a rotating assay.

RESULTS

Untreated HAEC constitutively expressed ICAM-1 on their surface but neither expressed E-/P-selectin, VCAM-1, nor shedded soluble adhesion molecules. Exposure of HAEC to hypoxia or hypoxia and reoxygenation did not upregulate cell surface expression or shedding of adhesion molecules. In contrast, TNF-alpha significantly upregulated cell surface expression of ICAM-1, VCAM-1, and E-/P-selectin and led to the shedding of ICAM-1 and E-selectin. Combined treatment of HAEC with TNF-alpha, hypoxia and reoxygenation reduced E-/P-selectin surface expression and enhanced E-selectin shedding, but did not further influence ICAM-1 and VCAM-1. Soluble VCAM-1 was not detected. NK cell adhesion on HAEC increased 4-fold after TNF-alpha stimulation, but was not affected by hypoxia or hypoxia and reoxygenation.

CONCLUSIONS

Both the expression of endothelial adhesion molecules and rolling NK cell adhesion was upregulated by TNF-alpha but not by hypoxia alone or hypoxia followed by reoxygenation supporting the view that anti-inflammatory treatment may reduce ischemia/reperfusion injury.

Preconditioning by sevoflurane decreases biochemical markers for myocardial and renal dysfunction in coronary artery bypass graft surgery: a double-blinded, placebo-controlled, multicenter study

BACKGROUND

Preconditioning by volatile anesthetics is a promising therapeutic strategy to render myocardial tissue resistant to perioperative ischemia. It was hypothesized that sevoflurane preconditioning would decrease postoperative release of brain natriuretic peptide, a biochemical marker for myocardial dysfunction. In addition, several variables associated with the protective effects of preconditioning were evaluated.

METHODS

Seventy-two patients scheduled for coronary artery bypass graft surgery under cardioplegic arrest were randomly assigned to preconditioning during the first 10 min of complete cardiopulmonary bypass with either placebo (oxygen-air mixture only) or sevoflurane 4 vol% (2 minimum alveolar concentration). No other volatile anesthetics were administered at any time during the study. Treatment was strictly blinded to anesthesiologists, perfusionists, and surgeons. Biochemical markers of myocardial dysfunction and injury (brain natriuretic peptide, creatine kinase-MB activity, and cardiac troponin T), and renal dysfunction (cystatin C) were determined. Results of Holter electrocardiography were recorded perioperatively. Translocation of protein kinase C was assessed by immunohistochemical analysis of atrial samples.

RESULTS

Sevoflurane preconditioning significantly decreased postoperative release of brain natriuretic peptide, a sensitive biochemical marker of myocardial contractile dysfunction. Pronounced protein kinase C delta and epsilon translocation was observed in sevoflurane-preconditioned myocardium. In addition, postoperative plasma cystatin C concentrations increased significantly less in sevoflurane-preconditioned patients. No differences between groups were found for perioperative ST-segment changes, arrhythmias, or creatine kinase-MB and cardiac troponin T release.

CONCLUSIONS

Sevoflurane preconditioning preserves myocardial and renal function as assessed by biochemical markers in patients undergoing coronary artery bypass graft surgery under cardioplegic arrest. This study demonstrated for the first time translocation of protein kinase C isoforms delta and epsilon in human myocardium in response to sevoflurane.

Graft occlusion after deployment of the Symmetry Bypass System

Recently the Symmetry Bypass System (SJM, St. Paul, MN) became available. Now the system is frequently applied for vein-graft to aorta anastomoses in off-pump coronary artery bypass operations. This report describes a complication associated with the use of the Symmetry Bypass System (SJM) in a patient undergoing a standard off-pump coronary artery bypass procedure. A novel imaging system (SPY, Novadaq, Toronto, Canada) was applied for intraoperative assessment of graft function, and this system immediately diagnosed the occlusion of the proximal mechanical anastomosis caused by a mobile atheromatous aortic plaque.

The relevance of large strains in functional tissue engineering of heart valves

BACKGROUND

Exposing the developing tissue to flow and pressure in a bioreactor has been shown to enhance tissue formation in tissue-engineered heart valves. Animal studies showed excellent functionality in these valves in the pulmonary position. However, they lack the mechanical strength for implantation in the high-pressure aortic position. Improving the in vitro conditioning protocol is an important step towards the use of these valves as aortic heart valve replacements. In this study, the relevance of large strains to improve the mechanical conditioning protocol was investigated.

METHODS

Using a newly developed device, engineered heart valve tissue was exposed to increasing cyclic strain in vitro. Tissue formation and mechanical properties were analyzed and compared to unstrained controls.

RESULTS

Straining resulted in more pronounced and organized tissue formation with superior mechanical properties over unstrained controls. Overall tissue properties improved with increasing strain levels.

CONCLUSIONS

The results demonstrate the significance of large strains in promoting tissue formation. This study may provide a methodological basis for tissue engineering of heart valves appropriate for systemic pressure applications.

Detachment of the anterior leaflet of the tricuspid valve to expose perimembranous ventricular septal defects

BACKGROUND

Detachment of the septal leaflet of the tricuspid valve has been described for better access to perimembranous ventricular septal defects. Detachment confined to the anterior leaflet is less known, although it provides a better exposure of the subaortic area and puts less jeopardy on the conduction tissues.

METHODS

Data regarding 49 consecutive patients who had congenital perimembranous ventricular septal defect closure were retrospectively reviewed. Thirty-three patients (67%) underwent temporary detachment of the anterior leaflet of the tricuspid valve. The defect was closed with a Gore-Tex patch and a continuous suture. In 10 patients (29%), concomitant right ventricular outflow tract enlargement was performed. Follow-up was obtained in every patient (median time, 11 months; range, 2 to 26 months).

RESULTS

No early or late death occurred. Closure of the ventricular septal defect was complete, with no more than trivial residual jet leaks found in perioperative echocardiography. All patients were in sinus rhythm. The tricuspid valve never showed more than mild insufficiency after repair. No patient showed subaortic obstruction.

CONCLUSIONS

Detachment of the anterior leaflet of the tricuspid valve to expose the ventricular septal defect is a safe approach that allows rapid closure of the defect with a continuous suture and provides excellent results.

Tissue engineering of functional trileaflet heart valves from human marrow stromal cells

BACKGROUND

We previously demonstrated the successful tissue engineering and implantation of functioning autologous heart valves based on vascular-derived cells. Human marrow stromal cells (MSC) exhibit the potential to differentiate into multiple cell-lineages and can be easily obtained clinically. The feasibility of creating tissue engineered heart valves (TEHV) from MSC as an alternative cell source, and the impact of a biomimetic in vitro environment on tissue differentiation was investigated.

METHODS AND RESULTS

Human MSC were isolated, expanded in culture, and characterized by flow-cytometry and immunohistochemistry. Trileaflet heart valves fabricated from rapidly bioabsorbable polymers were seeded with MSC and grown in vitro in a pulsatile-flow-bioreactor. Morphological characterization included histology and electron microscopy (EM). Extracellular matrix (ECM)-formation was analyzed by immunohistochemistry, ECM protein content (collagen, glycosaminoglycan) and cell proliferation (DNA) were biochemically quantified. Biomechanical evaluation was performed using Instron(TM). In all valves synchronous opening and closing was observed in the bioreactor. Flow-cytometry of MSC pre-seeding was positive for ASMA, vimentin, negative for CD 31, LDL, CD 14. Histology of the TEHV-leaflets demonstrated viable tissue and ECM formation. EM demonstrated cell elements typical of viable, secretionally active myofibroblasts (actin/myosin filaments, collagen fibrils, elastin) and confluent, homogenous tissue surfaces. Collagen types I, III, ASMA, and vimentin were detected in the TEHV-leaflets. Mechanical properties of the TEHV-leaflets were comparable to native tissue.

CONCLUSION

Generation of functional TEHV from human MSC was feasible utilizing a biomimetic in vitro environment. The neo-tissue showed morphological features and mechanical properties of human native-heart-valve tissue. The human MSC demonstrated characteristics of myofibroblast differentiation.

Living, autologous pulmonary artery conduits tissue engineered from human umbilical cord cells

BACKGROUND

Tissue engineering represents a promising approach to in vitro creation of living, autologous replacements with the potential to grow, repair, and remodel. Particularly in a congenital operation, there is a substantial need for such implantation materials. We previously demonstrated fabrication of completely autologous, functional heart valves on the basis of peripheral vascular cells. Presently the feasibility of creating pulmonary artery conduits from human umbilical cord cells was investigated.

METHODS

Human umbilical cord cells were harvested and expanded in culture. Pulmonary conduits fabricated from rapidly bioabsorbable polymers were seeded with human umbilical cord cells and grown in vitro in a pulse duplicator bioreactor. Morphologic characterization of the generated neo-tissues included histology, transmission, and scanning electron microscopy. Characterization of extracellular matrix was comprised of immunohistochemistry. Extracellular matrix protein content and cell proliferation were quantified by biochemical assays. Biomechanical testing was performed using stress-strain and burst-stress tests.

RESULTS

Histology of the conduits revealed viable, layered tissue and extracellular matrix formation with glycosaminoglycans and collagens I and III. Cells stained positive for vimentin and alpha-smooth muscle actin. Scanning electron microscopy showed confluent, homogenous tissue surfaces. Transmission electron microscopy demonstrated elements typical of viable myofibroblasts, such as collagen, fibrils, and elastin. Extracellular matrix proteins were significantly lower compared with native tissue; the cell content was increased. The mechanical strength of the pulsed constructs was comparable with native tissue; the static controls were significantly weaker.

CONCLUSIONS

In vitro fabrication of tissue-engineered human pulmonary conduits was feasible utilizing human umbilical cord cells and a biomimetic culture environment. Morphologic and mechanical features approximated human pulmonary artery. Human umbilical cord cells demonstrated excellent growth properties representing a new, readily available cell source for tissue engineering without necessitating the sacrifice of intact vascular donor structures.

Endoscopic saphenous vein harvesting for CABG -- a randomized, prospective trial

BACKGROUND

The saphenous vein is an established conduit for coronary revascularization. Disadvantages of traditional harvest technique are significant pain and morbidity. We compared the endoscopic harvest technique with the traditional method.

METHOD

140 coronary artery bypass graft (CABG) patients were randomized into 2 groups: endoscopic vein harvesting (EVH; n = 80) and traditional open vein harvesting (OVH; n = 60). Analysis included preoperative risk factors for wound complication, harvesting time, graft injury, and intraoperative and postoperative complications. Patient follow-up lasted 3 months.

RESULTS

The preoperative risk profiles of the groups were comparable. In the EVH group, 5 patients (7.1 %) had to be switched to the open technique. EVH time was 45 +/- 6.2 min vs. 31.1 +/- 6.5 min. Two patients (2.5 %) had to be revised because of bleeding complication vs. 6 (10 %) in the OVH group. No local infections or wound complications were observed in the EVH group vs. 11 (18 %) cases in the OVH group. Two OVH cases (3.6 %) were readmitted for wound debridement. All EVH patients reported less pain and were completely satisfied by the cosmetic results.

CONCLUSION

EVH is a safe and efficient technique for CABG. Morbidity was significantly lower, with reduced pain and better cosmetic results. EVH time was significantly longer compared to the traditional harvesting technique.

A new source for cardiovascular tissue engineering: human bone marrow stromal cells

OBJECTIVE

Vascular-derived cells represent an established cell source for tissue engineering of cardiovascular constructs. Previously, cell isolation was performed by harvesting of vascular structures prior to scaffold seeding. Marrow stromal cells (MSC) demonstrate the ability to differentiate into multiple mesenchymal cell lineages and would offer an alternative cell source for tissue engineering involving a less invasive harvesting technique. We studied the feasibility of using MSC as an alternative cell source for cardiovascular tissue engineering.

METHODS

Human MSC were isolated from bone marrow and expanded in culture. Subsequently MSC were seeded on bioabsorbable polymers and grown in vitro. Cultivated cells and seeded polymers were studied for cell characterization and tissue formation including extracellular matrix production. Applied methods comprised flow cytometry, histology, immunohistochemistry, transmission (TEM) and scanning electron microscopy (SEM), and biochemical assays.

RESULTS

Isolated MSC demonstrated fibroblast-like morphology. Phenotype analysis revealed positive signals for alpha-smooth muscle actin and vimentin. Histology and SEM of seeded polymers showed layered tissue formation. TEM demonstrated formation of extracellular matrix with deposition of collagen fibrils. Matrix protein analysis showed production of collagen I and III. In comparison to vascular-derived cell constructs quantitative analysis demonstrated comparable amounts of extracellular matrix proteins in the tissue engineered constructs.

CONCLUSIONS

Isolated MSC demonstrated myofibroblast-like characteristics. Tissue formation on bioabsorbable scaffolds was feasible with extracellular matrix production comparable to vascular-cell derived tissue engineered constructs. It appears that MSC represent a promising cell source for cardiovascular tissue engineering.

Endovascular repair with bifurcated stent-grafts under local anaesthesia to improve outcome of ruptured aortoiliac aneurysms

INTRODUCTION

acute haemodynamic changes and/or loss of abdominal muscle tone can occur during induction of general anaesthesia and may be the Achilles' tendon in endovascular aneurysm repair (EVAR) of ruptured aortoiliac aneurysms (rAIA). The purpose of this study was to evaluate the use of local anaesthesia (LA) for EVAR to overcome these limitations.

METHODS

twenty-one consecutive patients with rAIA are included in this study. Twenty patients underwent EVAR under LA, and 1 patient was treated under general anaesthesia. Haemodynamics were stabilised during assessment of EVAR feasibility by CT-scan and during the procedure itself by controlled hypotension (MAP 50-60 mmHg) and moderate fluid resuscitation.

RESULTS

median procedure time was 120 min. Haemodynamics remained stable in all but 3 patients who required transfemoral balloon occlusion of the supra-renal aorta. Perioperative intubation was necessary in 5 patients because of respiratory distress (n=3), or retroperitoneal access (n=2). Temporary deterioration of renal function occurred in 6 patients, with 2 requiring hemofiltration. CT-scan confirmed sealing of the rAIA in all patients at discharge. 30-day mortality was 9.5% (2 deaths). In the median follow-up of 19 months, there were no deaths, but 3 endovascularre-interventions, 1 crossover femoro-femoral bypass, and 1 open surgical graft repair.

DISCUSSION

our series is the first to show that EVAR for rAIA can be safely performed under LA. This approach allows implantation of commercially available bifurcated SG and improves patient outcome.

[Septic endarteritis after angiography]

Infectious complications after angiography are rare. We treated a 72-year-old man who developed staphylococcus aureus endarteritis after angiography resulting in delayed rupture of the common iliac artery. Diagnostic problems, type of bacteria involved and therapeutic implications are discussed.

Mesenteric ischemia after a cardiac operation: arteriosclerotic versus vasospastic etiology

Gastrointestinal complications after extracorporeal circulation are rare but well known complications. We describe and illustrate 2 patients with occlusive intestinal ischemia of different origin presenting after cardiopulmonary bypass (CPB) and present the different therapeutic algorithm.

Technical details with the use of cryopreserved arterial allografts for aortic infection: influence on early and midterm mortality

PURPOSE

In situ repair with cryopreserved vascular allografts improves the results in the surgical treatment of aortic infection. This study evaluated the technical pitfalls with the use of allografts that influence early and midterm mortality.

METHODS

Between 1990 and 1999, 49 patients, 21 (43%) with a mycotic aneurysm and 28 (57%) with a prosthetic graft infection of the thoracic and abdominal aorta including pelvic and groin vessels, underwent in situ repair with cryopreserved arterial allografts. Seventeen patients (35%) had aortobronchial, aortoesophageal, or aortoenteric fistulas.

RESULTS

Allograft-related technical problems occurred in eight patients (16%) in this series, and they included: intraoperative rupture caused by allograft friability; allograftenteric fistula from ligated allograft side branches rupturing 8, 18, and 48 months after implantation; anastomotic failure caused by inappropriate mechanical stress; anastomotic stricture after partial replacement of infected prosthetic grafts; allograft failure caused by inappropriate wound drainage; and recurrence of infection after inappropriate duration of antifungal treatment. Seven of the eight technical problems (87%) occurred in the first 10 patients (80%) in this series. There was one technical failure in the remaining 39 patients (2.6%; P =.0002) because of various technical adaptations, such as critical selection of allografts, use of allograft strips supporting large anastomoses, sealing with antibiotic-impregnated fibrin glue, and change in technique of allograft side-branch ligature. The 30-day mortality rate was 6% for the whole series; however, it was 2.6% for last 39 patients, with no recurrence of infection or allograft-related late death.

CONCLUSIONS

In situ repair with cryopreserved arterial allografts achieves excellent early and late results in the treatment of aortic infection. However, distinct allograft-related technical problems had to be overcome to improve the outcome of patients with major vascular infections.