Elucidation of the genetic causes of bicuspid aortic valve disease

AIMS

The present study aims to characterize the genetic risk architecture of bicuspid aortic valve (BAV) disease, the most common congenital heart defect.

METHODS AND RESULTS

We carried out a genome-wide association study (GWAS) including 2236 BAV patients and 11 604 controls. This led to the identification of a new risk locus for BAV on chromosome 3q29. The single nucleotide polymorphism rs2550262 was genome-wide significant BAV associated (P = 3.49 × 10-08) and was replicated in an independent case-control sample. The risk locus encodes a deleterious missense variant in MUC4 (p.Ala4821Ser), a gene that is involved in epithelial-to-mesenchymal transformation. Mechanistical studies in zebrafish revealed that loss of Muc4 led to a delay in cardiac valvular development suggesting that loss of MUC4 may also play a role in aortic valve malformation. The GWAS also confirmed previously reported BAV risk loci at PALMD (P = 3.97 × 10-16), GATA4 (P = 1.61 × 10-09), and TEX41 (P = 7.68 × 10-04). In addition, the genetic BAV architecture was examined beyond the single-marker level revealing that a substantial fraction of BAV heritability is polygenic and ∼20% of the observed heritability can be explained by our GWAS data. Furthermore, we used the largest human single-cell atlas for foetal gene expression and show that the transcriptome profile in endothelial cells is a major source contributing to BAV pathology.

CONCLUSION

Our study provides a deeper understanding of the genetic risk architecture of BAV formation on the single marker and polygenic level.

Adults With Congenital Heart Disease—a New, Expanding Group of Patients

BACKGROUND

Congenital heart anomalies are the most common type of organ malformation, affecting approximately 1% of all newborn infants. More than 90% of these children now survive into adulthood. They need to be cared for by specialists for adults with congenital heart disease (ACHD), as well as by family physicians, internists, and cardiologists who are adequately versed in the basic management of persons with this lifelong condition.

METHODS

This review is based on pertinent publications retrieved by a selective literature search, including guidelines and consensus statements from Germany and abroad.

RESULTS

Cardiovascular malformations cover a very wide spectrum, and the evidence base for the treatment of older patients with these conditions is scant. Congestive heart failure, arrhythmias, and the sequelae of pulmonary arterial hypertension are the main contributors to cardiac morbidity and mortality. Pregnancy counseling, endocarditis prophylaxis, vaccinations, and psychosocial aspects must be targeted to each individual patient. Neither the affected patients nor their family physicians are yet adequately acquainted with the recently created care structures for this patient group.

CONCLUSION

The care of ACHD is a multidisciplinary task that requires basic care by primary care physicians as well as the involvement of specialized cardiologists in order to ensure optimal individualized treatment.

Impact of Intermittent Functional Internal Iliac Artery Occlusion on Spinal Cord Blood Supply during TEVAR

BACKGROUND

Measuring transcranial motor evoked potentials (EPs) and somatosensory EPs is a well-established method to assess spinal cord function during thoracic endovascular aortic repair (TEVAR). Functional occlusion of one or both internal iliac arteries by large bore sheaths during TEVAR can cause unilateral intermittently EP loss.

METHODS

Between 2006 and 2016, 194 patients underwent TEVAR entailing EP monitoring. The ISIS IOM System (Inomed Medizintechnik GmbH, Emmendingen, Germany) was employed in all patients. EPs were recorded after inducing anesthesia, during the procedure, and before discontinuing anesthesia.

RESULTS

We observed a unilateral intermittently EP decrease or loss in 12 (6.2%) patients. Most events were ipsilateral (9 of 12). The underlying pathologies were descending aortic aneurysm in six patients and type B dissection in six patients. An evoked-potential decrease or loss was always associated with the insertion of large bore stent-graft-introducing sheaths. The median duration of the unilaterally EP decrease or loss was 16 (10; 31) minutes (range, 2-77 minutes) with baseline values re-established at the end of the procedure after sheath removal in all cases. No patient developed irreversible symptomatic spinal cord ischemia.

CONCLUSION

A functional occlusion of internal iliac arteries via large bore TEVAR-introducing sheaths is associated with a unilateral intermittent decrease in or loss of EPs returning to baseline after sheath removal. This observation highlights the importance of the internal iliac arteries as one of the major spinal cord's blood supply territories, and may serve as a stimulus to reduce the duration of sheath indwelling to a minimum.

Outcomes of Early-Onset Acute Type A Aortic Dissection - Influence of Etiologic Factors

BACKGROUND

Outcomes of early-onset acute type A aortic dissection (ATAAD) associated with Marfan syndrome (MFS) are known, but not with other etiologies. Methods and Results: ATAAD patients from 2 centers (n=1,001) were divided into 2 groups: age ≤45 years (n=93) and age >45 years (n=908). Although in-hospital death and 10-year survival were similar (12% vs. 7% and 62.6% vs. 67.3%), the 10-year aortic event-free survival differed (50.0% vs. 80.2%; P<0.01). ATAAD patients from 3 centers (n=132), all aged ≤45 years, were divided into 5 groups: lone hypertension (HTN, n=71), MFS (n=23), non-syndromic familial thoracic aortic aneurysm and dissection (NS-FTAAD, n=16), bicuspid aortic valve (BAV, n=11), and no known etiologic factor (n=11). The incidence of severe aortic insufficiency varied between groups (HTN: 11%, MFS: 39%, NS-FTAAD: 38%, BAV: 55%, no known factor: 46%; P<0.01), whereas in-hospital death did not (14%, 22%, 0%, 0%, and 9%; P=0.061). The 10-year survival was 52.2%, 64.7%, 83.6%, 100%, and 90.9%, respectively, and 10-year aortic event-free survival was 55.6%, 36.3%, 77.5%, 90.0%, and 30.0%. Median descending aorta growth (mm/year) was 1.1 (0.1-3.4), 2.3 (0.3-5.3), 1.9 (1.3-2.7), 0.9 (-0.1-2.0), and 1.0 (-0.2-2.9) (P=0.15), respectively.

CONCLUSIONS

Late aortic events are common in young ATAAD patients. Known etiologic factors, though not BAV, negatively influence late outcomes in these patients.

Benefits and Risks of Prophylactic Cerebrospinal Fluid Catheter and Evoked Potential Monitoring in Symptomatic Spinal Cord Ischemia Low-Risk Thoracic Endovascular Aortic Repair

Background To assess risks and benefits of a standardized strategy to prevent symptomatic spinal cord ischemia (SSCI) after thoracic endovascular repair (TEVAR) using routine cerebrospinal fluid (CSF) catheter placement and evoked potential (EP) monitoring.

Methods One hundred and ninety-five patients underwent 223 SSCI low-risk TEVAR procedures between 1998 and 2014. CSF catheter was used to measure CSF pressure and drain CSF if necessary throughout the procedure and up to 24 hours thereafter. EPs were used to monitor spinal cord integrity throughout the procedure.

Results Underlying pathologies included descending thoracic aortic aneurysm in 115 (52%), type B aortic dissection in 85 (38%), traumatic aortic rupture in 16 (7%), and others in 7 (3%) patients. CSF catheter was inserted before TEVAR in 116 procedures (52%). Active CSF draining was required in 29 patients (25%). The CSF catheter caused no major and 11 (10%) minor complications. EP were monitored during 88 (40%) procedures. We observed a reduction in the amplitude, prolonged latencies, or complete signal loss in nine procedures. There were no EP monitoring-related complications. SSCI incidence was higher in patients without CSF drainage (0.8% vs 4.7%, p = 0.031).

Conclusion Use of CSF drainage is associated with a significant lower incidence of SSCI after SSCI low-risk TEVAR than nonuse, whereas the complication rate associated with CSF drainage insertion or removal is very low. Routine EP monitoring is a useful tool to detect immediate arterial inflow obstruction to the spinal cord. The combination of these two methods serves as a safe and reliable standardized strategy in reducing the incidence of SSCI to a minimum.

Valve-sparing aortic root replacement in a bicuspid aortic valve with papillary fibroelastoma

We present our surgical strategy in a patient with a bicuspid aortic valve Type I (R/N), aortic root aneurysm and papillary fibroelastoma on the aortic valve's cusp. He underwent valve-sparing aortic root replacement (David V Procedure); we also removed the papillary fibroelastoma from the fused right- and non-coronary cusp. In this case, we used a 34-mm straight Dacron graft for root replacement and an aortic annulus downsized to 30 mm. We use Hegar dilatators for the intraoperative measurement of the aortic annulus. The subvalvular sutures are pledged U-sutures and our usual technique in bicuspid aortic valve is to take 2 on each commissure and 5 on each side so that we end up with 12. For the reimplantation of the aortic rim, we prefer a semi-circumferential suture with a small needle. We plicate the non-fused left cusp, which is our reference for the later reconstruction of the common right- and non-coronary cusp. The key strategy of our bicuspid valve reconstruction is aiming at a 180° non-fused commissure orientation and cusp plication. The coronary ostia and aortic root are marked intraoperatively with a radiopaque marker to facilitate postoperative diagnostics and any future interventions including later catheter-based valve interventions.

Descendo-bifemoral bypass grafting and renal artery revascularization to treat complex obliterative arteriopathy

OBJECTIVES

Our goal was to describe a new standardized approach in patients with extensive obliterative arteriopathy aimed at distal revascularization and surgical kidney recruitment via descendo-bifemoral bypass grafting and renal artery revascularization.

METHODS

Three patients with Leriche's syndrome and either a compromised single kidney or unilateral significant renal artery stenosis were treated with a standardized surgical approach, restoration of distal perfusion via descendo-bifemoral bypass with synchronous ( n  = 2) left-sided renal artery revascularization or metachronous ( n  = 1) right-sided renal artery revascularization.

RESULTS

The intended surgical aim was achieved successfully in all 3 cases. All patients showed a decline in serum creatinine levels. One patient who needed substitution therapy was free from dialysis 3 months after surgery. Additionally, blood pressure management was substantially reduced because uncontrolled peak systolic episodes were no longer observed and pharmacotherapeutic agents could be partially withdrawn.

CONCLUSIONS

Distal revascularization and surgical kidney recruitment via descendo-bifemoral bypass and renal artery revascularization is a promising option to treat complex obliterative arteriopathy.

Unequal pressure distribution along the jaws of currently available vascular clamps: do we need a new aortic clamp?

OBJECTIVES

The pressure along vascular clamp jaws may be unequally distributed, with greater pressure near the clamp hinge than at its top. Such unequal pressure distribution may cause aortic injury, especially in large aortas. We evaluated pressure distribution along different currently availably clamp jaws.

METHODS

Seven descending thoracic aortas from pigs (diameter 2.0-3.0 cm) were plainly dissected and all side arteries closed. Aortas were filled up with water and cross-clamped. The pressure inside the aorta was raised to 100 mmHg and the aorta was clamped so tightly that no water exited from the distal aortic end. Each aorta was clamped seven times at different sites with the following clamps: DeBakey, Satinsky, femoral, iliac, Chitwood, angled handle Fogarty and straight handle Fogarty. The pressure along the clamp jaws was measured with a pressure-detecting film placed between the clamp jaws and aorta. The collagen-fibre disorganization was examined in haemotoxylin-eosin- and Elastica van Gieson-stained tissue samples.

RESULTS

The DeBakey clamp revealed the lowest maximum pressure along the clamp jaws after complete aortic occlusion (1.43 ± 0.49 MPa), whereas the Chitwood clamp's pressure was the highest (3.26 ± 1.93 MPa, P < 0.001). The angled handle Fogarty clamp displayed the lowest difference between maximum pressures across the jaws (33%), with the greatest difference measured in the iliac (72%) and Chitwood (66%) clamps. The highest collagen-fibre disorganization score was observed in the proximal-to-the-clamp-hinge quartile after clamping with the angled handle Fogarty (2.8 ± 0.4), straight handle Fogarty (2.3 ± 0.8) and Chitwood (2.3 ± 0.5) clamps.

CONCLUSIONS

The pressure along clamp jaws is unequally distributed in all the currently available vascular clamps. The Chitwood clamp is associated with the highest maximum pressure during complete aortic occlusion and with the most unequal pressure distribution along the jaws.

[The staged approach--an overview on a strategy to reduce spinal cord injury in thoracoabdominal aortic aneurysm repair]

The spinal cord is particularly susceptible to ischaemic injury following repair of extensive descending thoracic and thoracoabdominal aortic aneurysms (TAAA). For the past decade, the Mount Sinai group in New York has intensively studied the anatomy of the extensive vascular network surrounding the spinal cord, as well as its dynamic morphology in response to decreased blood pressure and flow. Along with clinical data, experimental findings gave rise to the Collateral Network Concept, by which spinal cord injury in open TAAA repair can be significantly reduced. With the more recent widespread use of endovascular repair, strategies to prevent ischaemic spinal cord damage after extensive segmental artery sacrifice/occlusion are still evolving. The hypothesis that dividing extensive aneurysm repair into two steps may mitigate the impact of diminished blood flow to the collateral network has led to a recently conducted series of staged repair experiments. By exploiting the resources of the collateral network, spinal cord injury could be minimised in staged open, as well as in staged hybrid repair and seems equally adoptable for endovascular procedures. The contribution presented herein provides an overview of clinical and experimental studies on the staged approach. Furthermore, it briefly assesses the anatomic rationale for the collateral network concept.