No abstract

The present study was performed to examine pressure transduction to the thoracic cavity during topical negative pressure (TNP) therapy of a sternotomy wound. Seven pigs underwent median sternotomy. Pressure transduction catheters were placed on the anterior surface of the heart (under the foam), in the pericardium (under the heart), in the left pleura and in the oesophagus at the level of the heart. The wound was sealed as for TNP therapy. The vacuum source was set to deliver negative pressures between -50 and -200 mmHg. The pressure on the anterior surface of the heart changed in a linear relationship with the applied negative pressure and was slightly lower than the applied negative pressure (-102 +/- 9 mmHg at delivered -125 mmHg). Further down in the thoracic cavity, in the pericardium (under the heart), in the left pleura and in the oesophagus, the wound pressure was only slightly affected by TNP therapy. In conclusion during TNP therapy, negative pressure is effectively transmitted to anterior portions of the heart. This may explain our recent findings that TNP increases microvascular blood flow in the myocardium. The pressure difference between the anterior and the posterior portions of the heart causes the right ventricle to be sucked up towards the posterior parts of the sternum, where it might be exposed to the sharp edges of the sternal bone, which may result in heart injury.

Shed blood is known to be a source of lipid micro-emboli in cardiac surgery. The aim of this study was to characterize the occurrence of these particles at different stages of the operation, and to study their occurrence in the circulation at multiple time-points after the retransfusion of shed blood. Forty-four patients undergoing routine surgery with cardiopulmonary bypass were included. Blood was sampled from the surgical field at different sampling locations during the operation. Shed blood was collected in a transfusion bag and retransfused. After which, blood was sampled from the arterial line of the heart-lung machine. A Coulter counter was used for particle determinion. The mean volume of shed blood collected was 340+/-215 ml. Particles in the size range 10-60 microm were found at varying concentrations, with the highest concentrations being found in blood collected after cannulation and from the pleura. After retransfusion of this blood, a biphasic response was seen in the blood drawn from the efferent line of the heart-lung machine. Particles are found in shed blood at all times during cardiac surgery, and when this blood was retransfused an increase was seen in particle concentration in the heart-lung machine.

No abstract

The use of a mini-CPB system combined with a low dose of heparin reduced the need for blood transfusions and may facilitate the faster mobilization of the patients.

Background: Topical negative pressure (TNP), widely used in wound therapy, is known to stimulate wound edge blood flow, granulation tissue formation, angiogenesis, and revascularization. We have previously shown that application of a TNP of -50 mmHg to the myocardium significantly increases microvascular blood flow in the underlying tissue. We have also shown that a myocardial TNP levels between -75 mmHg and -150 mmHg do not induce microvascular blood flow changes in the underlying myocardium. The present study was designed to elucidate the difference between -25 mmHg and -50 mmHg TNP on microvascular flow in normal and ischemic myocardium.

Background: Up-regulation of vascular endothelin type B (ET B ) receptors is implicated in the pathogenesis of cardiovascular disease. Culture of intact arteries has been shown to induce similar receptor alterations and has therefore been suggested as a suitable method for, ex vivo, in detail delineation of the regulation of endothelin receptors. We hypothesize that mitogen-activated kinases (MAPK) and protein kinase C (PKC) are involved in the regulation of endothelin ET B receptors in human internal mammary arteries.

Background112 patients who received small and medium sized St.Jude Regent heart valves (19-25 mm) at 7 Scandinavian centers were studied between January 2003 and February 2005 to obtain non-invasive data regarding the hemodynamic performance at rest and during Dobutamine stress echocardiography (DSE) testing one year after surgery.Material and methods46 woman and 66 men, aged 61.8 ± 9.7 (18-75) years, were operated on for aortic regurgitation (17), stenosis (65), or mixed dysfunction (30). Valve sizes were 19 mm (6), 21 mm (33), 23 mm (41), 25 mm (30). Two patients receiving size 27 valves were excluded from the hemodynamic evaluation. Pledgets were used in 100 patients, everted mattress in 66 and simple interrupted sutures in 21. Valve orientation varied and was dependent on the surgeons' choice. 34 patients (30.4%) underwent concomitant coronary artery surgery.ResultsThere were two early deaths (1.8%) and three late deaths, one because of pancreatic cancer. Late events during follow-up were: non structural dysfunction (1), bleeding (2), thromboembolism (2). At one year follow up 93% of the patients were in NYHA classes 1-2 versus 47.8% preoperatively.Dobutamine stress echocardiography (DSE) was performed in a total of 66 and maximal peak stress was reached in 61 patients.During DSE testing, the following statistically significant changes took place: Heart rate increased by 73.0%, cardiac output by 85.5%, left ventriclular ejection fraction by 19.6%, and maximal mean prosthetic transvalvular gradient by 133.8%, whereas the effective orifice area index did not change.Left ventricular mass fell during one year from 215 ± 63 to 197 ± 62 g (p < 0.05).ConclusionThe Dobutamine test induces a substantial stress, well suitable for echocardiographic assessment of prosthesis valve function and can be performed in the majority of the patients. The changes in pressure gradients add to the hemodynamic characteristics of the various valve sizes.In our patients the St. Jude Regent valve performed satisfactory at rest and under pharmacological stress situation.