Hypothermic continuous machine perfusion enables preservation of energy charge and functional recovery of heart grafts in an ex vivo model of donation following circulatory death.

OBJECTIVES: Cardiac transplantation using hearts from donors after circulatory death (DCD) is critically limited by the unavoidable warm ischaemia and its related unpredictable graft function. Inasmuch as hypothermic machine perfusion (MP) has been shown to improve heart preservation, we hypothesized that MP could enable the use of DCD hearts for transplantation. METHODS: We recovered 16 pig hearts following anoxia-induced cardiac arrest and cardioplegia. Grafts were randomly assigned to two different groups of 4-h preservation using either static cold storage (CS) or MP (Modified LifePort© System, Organ Recovery Systems©, Itasca, Il). After preservation, the grafts were reperfused ex vivo using the Langendorff method for 60 min. Energetic charge was quantified at baseline, post-preservation and post-reperfusion by measuring lactate and high-energy phosphate levels. Left ventricular contractility parameters were assessed both in vivo prior to ischaemia and ex vivo during reperfusion. RESULTS: Following preservation, the hearts that were preserved using CS exhibited higher lactate levels (57.1 ± 23.7 vs 21.4 ± 12.2 µmol/g; P < 0.001), increased adenosine monophosphate/adenosine triphosphate ratio (0.53 ± 0.25 vs 0.11 ± 0.11; P < 0.001) and lower phosphocreatine/creatine ratio (9.7 ± 5.3 vs 25.2 ± 11; P < 0.001) in comparison with the MP hearts. Coronary flow was similar in both groups during reperfusion (107 ± 9 vs 125 ± 9 ml/100 g/min heart; P = ns). Contractility decreased in the CS group, yet remained well preserved in the MP group. CONCLUSION: MP preservation of DCD hearts results in improved preservation of the energy and improved functional recovery of heart grafts compared with CS.

Hypothermic continuous machine perfusion improves metabolic preservation and functional recovery in heart grafts.

The number of heart transplants is decreasing due to organ shortage, yet the donor pool could be enlarged by improving graft preservation. Hypothermic machine perfusion (MP) has been shown to improve kidney, liver, or lung graft preservation. Sixteen pig hearts were recovered following cardioplegia and randomized to two different groups of 4-hour preservation using either static cold storage (CS) or MP (Modified LifePort© System, Organ Recovery Systems, Itasca, Il). The grafts then underwent reperfusion on a Langendorff for 60 min. Energetic metabolism was quantified at baseline, postpreservation, and postreperfusion by measuring lactate and high-energy phosphates. The contractility index (CI) was assessed both in vivo prior to cardioplegia and during reperfusion. Following reperfusion, the hearts preserved using CS exhibited higher lactate levels (56.63 ± 23.57 vs. 11.25 ± 3.92 µmol/g; P < 0.001), increased adenosine monophosphate/adenosine triphosphate (AMP/ATP) ratio (0.4 ± 0.23 vs. 0.04 ± 0.04; P < 0.001), and lower phosphocreatine/creatine (PCr/Cr) ratio (33.5 ± 12.6 vs. 55.3 ± 5.8; P <0.001). Coronary flow was similar in both groups during reperfusion (107 ± 9 vs. 125 + /-9 ml/100 g/min heart; P = ns). CI decreased in the CS group, yet being well-preserved in the MP group. Compared with CS, MP resulted in improved preservation of the energy state and more successful functional recovery of heart graft.

Vertical vascular ring around right mainstem bronchus.

An 18-year-old male patient was referred with an atypical form of vascular ring consisting of a right aortic arch, a right descending aorta, a persistent right ligamentum arteriosum, and a dilated right pulmonary artery in the setting of discontinuous pulmonary arteries with a single functional right lung. The initial presentation was that of pneumonia of the right lung and later evaluation revealed the right mainstem bronchus was squeezed between the descending aorta and the dilated right pulmonary artery. Surgical exploration disclosed the right-sided ligamentum arteriosum was running under the right mainstem bronchus and hereby was completing a vertical vascular ring. Decompression was achieved through surgical and bronchoscopic treatment.

Endovascular stenting of juvenile vessels: consequence of surgical stent removal on vessel architecture.

AIMS: To investigate the effect of stenting and later surgical removal on the architecture and therefore growth potential of juvenile vessels. METHODS AND RESULTS: Stents were implanted in the carotid artery and jugular vein of six 6-week-old lambs. Ten weeks later, stents were excised and the vessels closed without the use of patch material. After another 10 weeks, the vessel size (treated and untreated control side) was measured angiographically and the animals terminated for histology. All arteries were patent: treated arterial size was 9 +/- 1 mm compared with 11 +/- 1 mm on the control side (P = ns). Two veins were completely occluded and two severely stenosed; vessel size was smaller compared with the control side (8 +/- 8 vs. 14 +/- 5 mm; P = 0.02). Preserved vessel wall integrity was observed in both arteries and veins (except for local rupture of the internal elastic lamina with neointimal formation in two arteries leading to mild stenosis). CONCLUSION: Vessel wall architecture remains well preserved after surgical removal of stents implanted in juvenile arteries and veins. However, stenting and subsequent surgical removal results in a high risk of venous thrombosis (probably due to the lower blood velocity, lower pressure, and the absence of pulsatility in venous vessels).

Acute retrograde aortic dissection during endovascular repair of a thoracic aortic aneurysm.

Endovascular aneurysm exclusion represents a valuable alternative treatment for descending thoracic aortic aneurysms. Although the minimally invasive character of this procedure is obvious, major complications are possible. We report a 77-year-old male who developed acute retrograde dissection of the aortic arch and ascending aorta during endovascular stent-grafting of a descending aortic aneurysm. Emergent open surgical repair provided a successful outcome.