[Paravalvular leak following surgical valve replacement: is there a role for percutaneous paravalvular leak reduction?]

After valve replacement, significant paravalvular leaks (PVL) may develop in up to 12.5% of the cases. Signs and symptoms include congestive heart failure and/or haemolysis and therefore may require reintervention. Redo valve surgery is considered the therapy of choice for symptomatic patients, either by valve replacement or leak repair. Considering the risk of morbidity and mortality associated with a surgical reintervention and the high post-surgical recurrence of PVL, the endovascular treatment represents an attractive alternative to surgery for high risk patients. The percutaneous approach aims at PVL reduction by implantation of certain occluder devices. The procedure is technically feasible in 60 to 90% of the cases according to different series. Technical success is associated with clinical improvement in 50 to 80% of the cases.

Influence of reflow ventricular fibrillation and electrical defibrillation on infarct size in a canine preparation of myocardial infarction

STUDY OBJECTIVE - The aim of the study was to investigate the influence of reflow ventricular fibrillation and electrical defibrillation on infarct size in a model of myocardial ischaemia. DESIGN - Myocardial ischaemia was induced in an open chest canine model by occluding the left coronary artery for 2 h. This was followed by 6 h reperfusion. The influence of reflow fibrillation and internal electric defibrillation on infarct size was investigated and compared to dogs which did not develop fibrillation. Infarct size and its major determinants, rate-pressure product (RPP), area at risk (AR), and collateral flow (MBF), were measured and their relationships studied in the two situations, using uni- and multilinear regression analysis. SUBJECTS - 21 adult mongrel dogs of either sex were used in the studies, which were done under pentobarbitone anaesthesia. Two were excluded because they developed ventricular fibrillation soon after coronary occlusion, and one did not survive reflow ventricular fibrillation. Of the remaining 18 dogs, six developed reflow ventricular fibrillation and were compared to the control group of 12 which did not develop fibrillation. MEASUREMENTS and RESULTS - A mean of 70.8(SEM 18.7) joules was required to revive the six dogs with reflow ventricular fibrillation. Difference in mean infarct size in the two groups did not reach significance [49.1(4.4) in fibrillation group v 38(6.2) in the controls]. The multiple linear regression model in the control group accounted for 91% of the variation in infarct size (IS): IS = -3.4 + 0.49 (AR) -21.8 (MBF) + 0.025 (RPP). The equation was not modified by including the reflow fibrillation dogs: IS = -3.1 + 0.52 (AR) - 19 (MBF) + 0.02 (RPP). Ischaemic determinants of infarct size in the reflow fibrillation dogs were computed in the control group equation to compare the infarct size predicted by the model to the measured infarct size in each individual dog in the reflow fibrillation group. There was no significant difference between the means: 12.9(2.9)% (predicted) v 14.9(2.5)% (measured). CONCLUSIONS - In this model of myocardial infarction, reflow ventricular fibrillation and low energy internal electric shocks do not damage the myocardium at risk significantly.

Influence of leukopenia on collateral flow, reperfusion flow, reflow ventricular fibrillation, and infarct size in dogs

Leukocytes contribute to myocardial damage during ischemia and reperfusion. However, the mechanism involved has not been clearly elucidated. The purpose of the present study was to determine whether leukocyte-induced myocardial damage is flow mediated. In open-chest dogs submitted to 2 hours of ischemia, area at risk, infarct size, and regional myocardial blood flow before, during, and after ischemia were measured. Leukopenia was induced by a two-step method (chemotherapy and antineutrophil serum) in a group of 14 dogs as compared to a control group of 18 dogs. The relation of infarct size to the major determinants of infarct size was analyzed by uni- and multilinear regressions. Seven control dogs had ventricular fibrillation at reperfusion compared to one dog with leukopenia. In the group with leukopenia the mean infarct size was smaller (31.1 +/- 5.8% of area at risk) than in the control group (47.7 +/- 2.9, p = 0.02). In addition, the two multiple linear regression equations were significantly different (p = 0.01). Myocardial blood flow to the central ischemic zone did not change significantly between 20 and 120 minutes of ischemia in the control dogs (n = 12; subendocardial = 0.08 +/- 0.03 vs 0.07 +/- 0.03 ml/min/gm; subepicardial = 0.20 +/- 0.07 vs 0.20 +/- 0.05 ml/min/gm) and in the dogs with leukopenia (n = 12; 0.07 +/- 0.02 vs 0.07 +/- 0.02 ml/min/gm and 0.15 +/- 0.004 vs 0.18 +/- 0.04 ml/min/gm). A similar reduction in myocardial blood flow was observed after 6 hours of reperfusion in the control dogs (0.34 +/- 0.07 ml/min/gm vs 1.02 +/- 0.11 at baseline, p less than 0.01) and in the dogs with leukopenia (0.25 +/- 0.04 vs 0.81 +/- 0.08 ml/min/gm, p less than 0.01). It was concluded that the leukocyte-dependent myocardial injury did not appear to be mediated through a flow mechanism during either ischemia or reperfusion.

Lignocaine in experimental myocardial infarction: failure to prevent neutrophil accumulation and ventricular fibrillation and to reduce infarct size

Growing evidence supports the concept that neutrophils accumulating in reperfused ischaemic myocardium play a detrimental role in evolving infarction. Lignocaine, an antiarrhythmic drug commonly used clinically, interferes with neutrophil function in vitro and potentially in vivo. To test the hypothesis that lignocaine may influence infarct size by reducing neutrophil accumulation in reperfused ischaemic myocardium, 31 dogs underwent a 2 h occlusion of the left anterior descending coronary artery, followed by 6 h of reperfusion. One group of dogs received saline (controls) the other a perfusion of lignocaine 0.06 mg.kg-1.min-1 starting 30 min before coronary occlusion and lasting for the duration of the experiment. Blood lignocaine concentrations at the onset of reperfusion were 3.3(0.6) micrograms.ml-1. 111Indium labelled autologous neutrophils were injected at the time of occlusion and their accumulation in the myocardium measured by digital scintigraphy of heart slices. The area at risk and infarct size were evaluated by planimetry of the heart slices (7 mm) after perfusion of Evans blue dye and triphenyltetrazolium staining. Ventricular fibrillation occurred in six controls and in five dogs receiving lignocaine. The phenomenon occurred early during the occlusion period in the lignocaine group (five dogs) and at reperfusion in controls (five dogs; p less than 0.05). In the remaining 20 dogs, 10 in each group, a linear correlation was found between myocardial 111In labelled neutrophil and circulating neutrophil counts at the onset of reperfusion (r = 0.076, p less than 0.05) and with infarct size (r = 0.96 and 0.74, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)