Pulmonary and aortic homografts, both cryopreserved and preserved in nutrient antibiotic solution, give similar results. All conduits will probably have to be replaced during the lifetime of the patient. In view of the worse performance of replacement conduits, techniques of repair that avoid the use of conduits should be further explored. Despite gradual deterioration of homograft conduits, they remain an important tool in the correction of many complex lesions with excellent 15-year patient survival.

Left ventriculotomy is a useful approach for closure of low muscular ventricular septal defects in selected patients.

No abstract

The current study characterizes the mechanical properties of the human thoracic duct and demonstrates a role for adrenoceptors, thromboxane, and endothelin receptors in human lymph vessel function. With ethical permission and informed consent, portions of the thoracic duct (2-5 cm) were resected and retrieved at T7-T9 during esophageal and cardia cancer surgery. Ring segments (2 mm long) were mounted in a myograph for isometric tension (N/m) measurement. The diameter-tension relationship was established using ducts from 10 individuals. Peak active tension of 6.24 Ϯ 0.75 N/m was observed with a corresponding passive tension of 3.11 Ϯ 0.67 N/m and average internal diameter of 2.21 mm. The equivalent active and passive transmural pressures by LaPlace's law were 47.3 Ϯ 4.7 and 20.6 Ϯ 3.2 mmHg, respectively. Subsequently, pharmacology was performed on rings from 15 ducts that were normalized by stretching them until an equivalent pressure of 21 mmHg was calculable from the wall tension. At low concentrations, norepinephrine, endothelin-1, and the thromboxane-A2 analog U-46619 evoked phasic contractions (analogous to lymphatic pumping), whereas at higher contractions they induced tonic activity (maximum tension values of 4.46 Ϯ 0.63, 5.90 Ϯ 1.4, and 6.78 Ϯ 1.4 N/m, respectively). Spontaneous activity was observed in 44% of ducts while 51% of all the segments produced phasic contractions after agonist application. Acetylcholine and bradykinin relaxed norepinephrine preconstrictions by ϳ20% and ϳ40%, respectively. These results demonstrate that the human thoracic duct can develop wall tensions that permit contractility to be maintained across a wide range of transmural pressures and that isolated ducts contract in response to important vasoactive agents. lymphatic system; lymph pump; lymphangion; lymphatic smooth muscle THE EXCESS FLUID AND PROTEIN of the interstitial spaces in almost all tissues of the body are collected and removed by the lymphatic system. The lymphatic capillaries converge into larger collecting lymphatics, and, ultimately, these terminate into large transport vessels, which return lymph to the blood circulation. The lymphatic system lacks a central pump to drive the transport of lymph. Instead, it is generally accepted that the lymphatic smooth muscle cells (LSMCs) in the collecting and transporting lymphatic vessel wall are responsible for propelling lymph forward by intrinsic contractions. The lymphatic vessels responsible for pumping are comprised of multiple contractile segments separated by unidirectional valves to prevent backflow, termed a lymphangion, and each lymphangion performs much like a cardiac ventricle to provide unidirectional pumping. The contractile part of the lymphatic vasculature can thus be likened to a system of ventricles in series (27). The thoracic duct is the largest lymphatic vessel in the human body. Under normal conditions (i.e., in healthy individuals), it is a low-flow system that drains up to 1 ml/min to the venous circulation (30,44). The volume and flow of lymph a...

Background: The Fontan procedure has revolutionized the treatment of univentricular hearts. However, it is associated with severe complications such as protein-losing enteropathy, plastic bronchitis, and peripheral edema that may involve the lymphatic circulation. We aimed to assess lymphatic function and morphology in patients with a univentricular circulation. Methods: The functional state of lymphatic vessels in the lower extremities of patients with a Fontan circulation (n=10) was investigated using the novel technique near-infrared fluorescence imaging and compared with an age-, sex-, and weight-matched control group of healthy volunteers (n=10). The lymphatic morphology was described using T2-weighted magnetic resonance imaging, and microvascular permeability was estimated by strain gauge plethysmography. Results: The Fontan patients had 17% lower lymphatic pumping pressure (50±3.1 mm Hg) compared with controls (60±2.8 mm Hg; P =0.0341) and a 62% higher contraction frequency (0.8±0.1 min −1 ) compared with the healthy controls (0.5±0.1 min −1 ; P =0.0432). Velocity by which the lymph is moved and refill time after manual emptying of the lymphatic vessels showed no differences between the 2 groups. The thoracic duct was elongated 10% ( P =0.0409) and with an abnormal course in the Fontan patients compared with normal. No difference in microvascular permeability was found between the 2 groups. Conclusions: Patients with a Fontan circulation have an impaired lymphatic pumping capacity and morphologically changed thoracic duct. Our results indicate a challenged lymphatic vasculature in the Fontan circulation and may play a role in the pathogenesis of the complications that are seen in Fontan patients. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT03379805.

At 10 years follow-up after mechanical mitral valve replacement, most children had suffered an adverse event. At 15 years, all children with a prosthesis<23 mm had outgrown their valve, but redo-mitral valve replacement with a larger size prosthesis was always possible, and carried low operative risk. Long-term anticoagulation was well tolerated. In children every effort should be made to preserve the native valve.

This study identifies age at operation, RACHS-1 risk category and bypass time as highly significant risk factors for mortality after paediatric open-heart surgery. It validates the RACHS-1 risk stratification method as applied to the subset of open-heart surgery, whilst accepting the limitations of such a system. The risk models formulated permit risk prediction and allow for analysis of surgical results. Such risk-adjustment is important when assessing performance and comparing outcomes amongst individuals or institutions.

Independently of hemodynamically important arch obstruction or residual aortic coarctation, specific aortic arch shape features late after successful aortic coarctation repair seem to be associated with worse left ventricular function. Analyzing 3-dimensional shape information via statistical shape modeling can be an adjunct to long-term risk assessment in patients after aortic coarctation repair.