Transmyocardial laser revascularisation in acutely ischaemic myocardium.

OBJECTIVE: Although recent experience suggests that transmyocardial laser revascularisation (TMLR) relieves angina, its mechanism of action remains undefined. We examined its functional effects and analysed its morphological features in an animal model of acute ischaemia. METHODS: A total of 15 pigs were randomised to ligation of left marginal arteries (infarction group, n = 5), to TMLR of the left lateral wall using a holmium:yttrium-aluminium garnet (Ho:YAG) laser (laser group, n = 5), and to both (laser-infarction group, n = 5). All the animals were sacrificed 1 month after the procedure. Haemodynamics and echocardiography with segmental wall motion score were carried out at both time intervals (scale 0-3: 0, normal; 1, hypokinesia; 2, akinesia; 3, dyskinesia). Histology of the involved area was analysed. RESULTS: Laser group showed no change of the segmental wall motion score of the involved area 30 min after the laser channels were made (score: 0 +/- 0). Infarction and laser infarction groups both showed a persistent and definitive increase of the segmental wall motion score (at 30 min: 1.6 +/- 0.3 and 2 +/- 0, respectively; at 1 month: 1.8 +/- 0.2 and 1.8 +/- 0.4, respectively). These increases were all statistically significant in comparison with baseline values (P < 0.5), however comparison between infarction and laser-infarction groups showed no significant difference. On macroscopic examination of the endocardial surface, no channel was opened. On histology, there were signs of neovascularisation around the channels in the laser group, whereas in the laser-infarction group the channels were embedded in the infarction scar. CONCLUSIONS: In this acute pig model, TMLR did not provide improvement of contractility of the ischaemic myocardium. To the degree that the present study pertains to the clinical setting, the results suggest that mechanisms other than blood flow through the channels should be considered, such as a laser-induced triggering of neovascularisation or neural destruction

Impact of duration of chest tube drainage on pain after cardiac surgery.

OBJECTIVE: This study was designed to analyze the duration of chest tube drainage on pain intensity and distribution after cardiac surgery. METHODS: Two groups of 80 cardiac surgery adult patients, operated on in two different hospitals, by the same group of cardiac surgeons, and with similar postoperative strategies, were compared. However, in one hospital (long drainage group), a conservative policy was adopted with the removal the chest tubes by postoperative day (POD) 2 or 3, while in the second hospital (short drainage group), all the drains were usually removed on POD 1. RESULTS: There was a trend toward less pain in the short drainage group, with a statistically significant difference on POD 2 (P=0.047). There were less patients without pain on POD 3 in the long drainage group (P=0. 01). The areas corresponding to the tract of the pleural tube, namely the epigastric area, the left basis of the thorax, and the left shoulder were more often involved in the long drainage group. There were three pneumonias in each group and no patient required repeated drainage. CONCLUSIONS: A policy of early chest drain ablation limits pain sensation and simplifies nursing care, without increasing the need for repeated pleural puncture. Therefore, a policy of short drainage after cardiac surgery should be recommended

J/psi production in relativistic heavy ion collisions from a multi-phase transport model

Using A Multi-Phase Transport (AMPT) model, we study J/psi production from interactions between charm and anti-charm quarks in initial parton phase and between D and Dbar mesons in final hadron phase of relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC). Including also the inverse reactions of J/psi absorption by gluons and light mesons, we find that the net number of J/psi from the parton and hadron phases is smaller than that expected from the superposition of initial nucleon-nucleon collisions, contrary to the J/psi enhancement predicted by the kinetic formation model. The production of J/psi is further suppressed if one includes the color screening effect in the parton phase. We have also studied the dependence of J/psi production on the charm quark mass and the effective charm meson mass.Comment: Figures redone with better statistic

Myocardial angiogenesis induction with bone protein derived growth factors (animal experiment).

Myocardial angiogenesis induction with vascular growth factors constitutes a potential strategy for patients whose coronary artery disease is refractory to conventional treatment. The importance of angiogenesis in bone formation has led to the development of growth factors derived from bovine bone protein. Twelve pigs (mean weight, 73 +/- 3 kg) were chosen for the study. In the first group (n = 6, growth factor group) five 100 micrograms boluses of growth factors derived from bovine bone protein, diluted in Povidone 5%, were injected in the lateral wall of the left ventricle. In the second group (n = 6, control group), the same operation was performed but only the diluting agent was injected. All the animals were sacrificed after 28 days and the vascular density of the left lateral wall (expressed as the number of vascular structures per mm2) as well as the area of blood vessel profiles per myocardial area analysed were determined histologically with a computerised system. The growth factor group had a capillary density which was significantly higher than that of the control group: 12.6 +/- 0.9/mm2 vs 4.8 +/- 0.5/mm2 (p < 0.01). The same holds true for the arteriolar density: 1 +/- 0.2/mm2 vs 0.3 +/- 0.1/mm2 (p < 0.01). The surface ratios of blood vessel profiles per myocardial area were 4900 +/- 800 micron 2/mm2 and 1550 +/- 400 micron 2/mm2 (p < 0.01) respectively. In this experimental model, bovine bone protein derived growth factors induce a significant neovascularisation in healthy myocardium, and appear therefore as promising candidates for therapeutic angiogenesis

Imaging of the abdominal aorta during examination of patients referred for transthoracic echocardiography.

BACKGROUND: Screening for aneurysm of abdominal aorta (AAA) in the general population is costly and unrealistic, but examination of the abdominal aorta appears reasonable in a high risk cardiological population. METHOD: As the abdominal aorta is easily accessible to standard transthoracic echocardiographic equipment, we tested this hypothesis in 301 consecutively referred patients (182 men, 119 women, mean age 58.6 +/- 16.5 years) by imaging the abdominal aorta at the end of the cardiac examination. RESULTS: After exclusion of three patients operated on for AAA before, the native infrarenal segment most often involved in AAA was visualised in 297 out of 298 patients (99.7%), and the aortic bifurcation was seen satisfactorily in 285 of them (95.6%). The abdominal aorta was dilated (> or = 2 cm) in 44 patients (15%), all but one of whom were > 50 years old; 17 of these (5.7%) had AAA defined as segmental dilation with a maximum diameter of > or = 3 cm (15 men, 2 women, age 67.4 +/- surgical repair and one endovascular repair within one year after completion of the data collection. Their mean age was 70.1 +/- 7.9 years, ranging from 58 to 80 years. No significant surgical morbidity and no mortality was observed. CONCLUSIONS: Prevalence of dilative alterations of the abdominal aorta is high in cardiological patients. Visualisation during transthoracic echocardiography of the most important infrarenal segment is nearly always feasible (99.7%), including its bifurcation (95.6%). Since detection of life-threatening but asymptomatic AAA may save lives by offering safe elective surgical treatment or stenting, opportunistic examination of the abdominal aorta during routine transthoracic echocardiography, which involves little time and no additional cost, would appear to be highly effective and should be included in routine examinations, at least in patients over 50 years of age

Prélèvement minimal invasif de la veine saphène interne pour pontages aorto-coronariens [Minimally invasive internal saphenous vein harvesting for coronary artery bypass]

Harvesting of the great saphenous vein for coronary artery bypass grafting is usually performed through long cutaneous incisions. We report our experience of minimally invasive harvest of the saphenous vein using the "Mini Harvest System". This device is composed of a blade coupled to a light source. Through a small cutaneous incision, the blade is placed under the skin and allows progressive dissection of the vein under direct vision. We compare this technique ("minimal invasive" group, n = 48) to the conventional method in which extensive incisions are performed along the saphenous vein course ("standard", n = 54). Both groups are comparable in term of age, sex, diabetes, peripheral arterial disease or obesity. The number of bypass performed is also comparable in the two groups. The ratio of the mean length of the cutaneous incision and the mean length of the vein was 35.4 +/- 5.9% for the "minimal invasive" group and 104.5 +/- 23.3% for the "standard" group (p < 0.001). The local complication rate is significantly reduced with a reduction in local post-operative pain (2% vs. 17%, p = 0.01), a better healing (100% vs. 79%, p = 0.01), a reduction in hematoma (31% vs. 52%, p = 0.03) and in oedema (37% vs. 59%, p = 0.03). We conclude that besides the evident aesthetic benefit, minimally invasive harvest of the saphenous vein allows for a better cicatrization and reduces the post-operative discomfort without compromising the aorto-coronary bypass procedure

Intra-aortic balloon: evaluation of heparin-coating under various experimental conditions.

In a calf model, heparin coated intra-aortic balloon (IAB) was compared with standard balloon. In group 1, 9 of each IAB type were set to the automatic mode for 15 min, 45 min and 6 hours respectively, while in group 2, 3 of each IAB type were left deflated during 20 minutes to simulate balloon dysfunction. At the end of the procedures, 3 samples of each IAB were analyzed with scanning electron microscopy (SEM) for surface deposits. Macroscopically, the 12/12 heparin coated IAB of both groups and the 9/9 standard IAB of group 1 were free of deposits, whereas the 3/3 standard IAB of group 2 exhibited clot deposits. SEM revealed deposit-free surfaces in the 36/36 heparin coated samples of both groups, while 14/27 standard samples of group 1 (p<0.01 when compared with heparin coated samples) and 8/9 standard samples of group 2 (p = 0.02, same comparison) disclosed blood cells and fibrin deposits. Morphometrically, the proportion of standard sample surfaces covered with deposits, estimated according to a score system (0% = 0; 0.1-25% = 1; 25.1-50% = 2; 50.1-75% = 3; 75. 1-100% = 4), was 0.69+/-0.82 in group 1 (p<0.01 when compared with heparin coated samples) and 1.22+/-0.83 in group 2 (p<0.01, same comparison). Thus heparin coated IAB presents no deposits either after 6 hours of intravascular ballooning or after 20 minutes of stagnation. It seems to be a promising strategy for patients with absolute or relative contraindications to systemic heparinization

Minimally invasive harvest of the saphenous vein for coronary artery bypass grafting.

BACKGROUND: Preparation of the great saphenous vein for coronary artery bypass grafts is traditionally performed through one or many long cutaneous incisions. We describe the dissection of the great saphenous vein through small cutaneous incisions using the Mini Harvest System. METHODS: The device is composed of a retractor coupled to a light source. Introduced under the skin, above the anterior plane of the vein, it allows an easy preparation of the vein under direct vision. The entire vein can be dissected from the ankle to the groin through sequential cutaneous incisions along the leg. A prospective, randomized trial was performed to compare the minimally invasive vein harvest technique (group 1, n = 15) versus the standard method (group 2, n = 15). RESULTS: In addition to an internal mammary artery graft, 28 venous coronary bypass grafts were performed in group 1 (mean, 1.9 +/- 1.0) and 32 in group 2 (mean, 2.1 +/- 1.0). The mean cutaneous incision length divided by the mean length of the harvested vein was 10.8 cm/32.3 cm = 33% for group 1 and 37.6 cm/33.2 cm = 113% in group 2 (p < 0.001). Wounds were examined daily and a final assessment was performed on day 7. Better cicatrization, less hematoma and edema, and less pain were observed in group 1. CONCLUSIONS: Minimally invasive harvest of the great saphenous vein offers many advantages over the traditional harvest method. Besides the aesthetic aspect, healing is better and postoperative discomfort is reduced

Hemocompatibility of a coaxial pump catheter for less invasive heart surgery.

Off-pump coronary artery bypass (OPCAB) requires heart manipulation during exposure of the lateral and posterior walls of the heart, which may cause hemodynamic instability, mainly through right ventricular dysfunction. A coaxial atrial cannula connected to a minicentrifugal pump was developed to bypass the right heart. This study was designed to test the hemocompatibility of this pump ongoing for 6 h. In five calves (bodyweight, 70.3+/-4.2 kg), the pump was inserted and set to its maximal motor speed of 7000 rpm. Blood samples were taken for blood gas analyses, hematology and chemistry on an hourly basis. ANOVA was used for statistical analysis. During the 6-h run, hematocrit and red blood cell count were stable (p=0.77 and 0.87, respectively). Platelet count was not significantly altered (p=0.55). LDH was stable (p=0.61) and plasma free hemoglobin remained below 100 mg/l throughout the experiment. Adequate tissue perfusion was maintained as reflected by the stable mixed venous oxygen saturation (baseline, 72.5+/-2%, and 6 h, 65.6+/-3.4%) and no defect of any pump system was detected during this 6-h testing. This right heart minipump appears to have a minimal impact on red cells and platelets when set at its maximal speed for 6 h, underlining the hematological safety of the system