Paulo Sampaio Gutierrez

Catheter Ablation of Ventricular Epicardial Tissue A Comparison of Standard and Cooled-Tip Radiofrequency Energy

Background—Transthoracic epicardial catheter ablation is an emerging catheter ablation strategy being used clinically at increasing frequency. However, the efficacy of standard RF ablation on the epicardial surface of the heart is hindered by (1) the lack of convective cooling of the ablation electrode and (2) the varying presence of epicardial adipose tissue interposed between the ablation electrode and the target site. This experimental animal study examines the biophysical characteristics of radiofrequency (RF) ablation lesions generated by either standard or cooled-tip ablation of the ventricular epicardium. Methods and Results—Nonsurgical subxyphoid pericardial access was achieved in 10 normal goats and 7 pigs with healed myocardial infarctions. A 4-mm cooled-tip RF ablation catheter (continuous 0.9% saline circulation at 0.6 mL/s; goal temperature, 40°C; 60 seconds) was used to deliver epicardial ventricular lesions: 47 in normal tissue and 22 in infarcted tissue. Standard RF ablation lesions (n=33) using a 4-mm top catheter (goal temperature, 70°C; 60 seconds) were also placed on normal epicardial tissue. Lesions created with standard and cooled-tip RF ablation were 3.7±1.3 mm (25±16.8 W) and 6.7±1.7 mm (44.8±6.8 W) in depth, respectively. On scar tissue, lesions made with the cooled-tip catheter measured 14.6±2.7 mm in length, 11.8±2.9 mm in width, and 5.6±1.2 mm in depth (35.6±7.1 W). In areas covered by epicardial fat (3.1±1.2 mm thick), standard RF energy did not generate any appreciable lesions, but cooled-tip RF lesions were 4.1±2 mm in depth (45±4.4 W). Conclusions—Cooled-tip RF ablation can generate epicardial lesions more effectively than standard RF ablation and appears to be of particular benefit in ablating areas with overlying epicardial fat.

Syndromic and non-syndromic aneurysms of the human ascending aorta share activation of the Smad2 pathway

Common features such as elastic fibre destruction, mucoid accumulation, and smooth muscle cell apoptosis are co‐localized in aneurysms of the ascending aorta of various aetiologies. Recent experimental studies reported an activation of TGF‐β in aneurysms related to Marfan (and Loeys‐Dietz) syndrome. Here we investigate TGF‐β signalling in normal and pathological human ascending aortic wall in syndromic and non‐syndromic aneurysmal disease. Aneurysmal ascending aortic specimens, classified according to aetiology: syndromic MFS (n = 15, including two mutations in TGFBR2), associated with BAV (n = 15) or degenerative forms (n = 19), were examined. We show that the amounts of TGF‐β1 protein retained within and released by aneurysmal tissue were greater than for control aortic tissue, whatever the aetiology, contrasting with an unchanged TGF‐β1 mRNA level. The increase in stored TGF‐β1 was associated with enhanced LTBP‐1 protein and mRNA levels. These dysregulations of the extracellular ligand are associated with higher phosphorylated Smad2 and Smad2 mRNA levels in the ascending aortic wall from all types of aneurysm. This activation correlated with the degree of elastic fibre fragmentation. Surprisingly, there was no consistent association between the nuclear location of pSmad2 and extracellular TGF‐β1 and LTBP‐1 staining and between their respective mRNA expressions. In parallel, decorin was focally increased in aneurysmal media, whereas biglycan was globally decreased in aneurysmal aortas. In conclusion, this study highlights independent dysregulations of TGF‐β retention and Smad2 signalling in syndromic and non‐syndromic aneurysms of the ascending aorta. Copyright

Immunohistochemical characterization of infiltrating cells in human chronic chagasic myocarditis: Comparison with myocardial rejection process

Cellular subpopulations that infiltrate the heart in human chronic chagasic myocarditis were defined immunohistochemically in endomyocardial biopsy (EMB) specimens. T cells formed 96.3% of the inflammatory infiltrate, predominantly CD8+ (cytotoxic/ suppressor) T cells. The mean numbers of CD8+ and CD4+ (helper) T cells in the myocarditis were compared to those present in the myocardial rejection process. Mean numbers of CD8+ T cells were similar in both groups of EMB specimens while CD4+ T cell counts, CD4+/CD8+ ratios and CD4+ antigen expression were significantly lower in the chagasic group compared to the myocardial rejection group (P<0.002). The persistent lower number and diminished expression of CD4+ T cells suggest an immunological imbalance in patients with chronic chagasic myocarditis. A possible participation ofTrypanosoma cruzi parasites in the development of such immunological abnormalities is also discussed.

The Effect of Red Wine on Experimental Atherosclerosis: Lipid-Independent Protection ~

To assess the effect of red wine on atherosclerosis, New Zealand rabbits were given 1% cholesterol diet for 12 weeks and compared to animals that received the diet plus either red wine or nonalcoholic wine products (NAWP). Diet induced marked increases in total and LDL cholesterol; yet no significant changes in HDL and triglyceride concentrations occurred. In the control group, plaque area was 69 +/- 9% of the aortic surface, while in the wine and NAWP groups it was only 38 +/- 9 and 47 +/- 12%, respectively (P < 0.0001). The average intima/media thickness ratio was 0.60 +/- 0.2 in control animals, 0.14 +/- 0.09 in the wine group, and 0.39 +/- 0.19 in the NAWP group (P < 0.0001). No significant differences were noted in LDL oxidizability among treatments. Thus, both red wine and NAWP can prevent plaque formation in hypercholesterolemic rabbits despite significant increases in LDL. We speculate that anti-platelet effect, blockade of expression of endothelial cell adhesion molecules, and/or NO stimulation by red wine flavonoids are possible explanations.

Detection of Mycoplasma pneumoniae and Chlamydia pneumoniae in ruptured atherosclerotic plaques

This paper reports what is apparently the first observation of Mycoplasma pneumoniae in association with Chlamydia pneumoniae in thrombosed ruptured atheromas. We performed electron microscopy and in situ hybridization in specimens from three patients who died of acute myocardial infarction. These patients had typical symptoms of acute ischemic syndrome. Mycoplasmas were present mainly in the lipid core of the ruptured thrombosed plaque. Vulnerable atheromas are rich in cholesterol and may favor the growth of mycoplasmas, the only microorganisms that require cholesterol for survival. We suggest that the association of Mycoplasma pneumoniae and Chlamydia pneumoniae may increase the virulence of these microorganisms, favoring proliferation, plaque inflammation and possibly plaque rupture.

Differences in the distribution of versican, decorin, and biglycan in atherosclerotic human coronary arteries.

The distributions of versican, biglycan, and decorin have been examined in segments of normal and atherosclerotic human coronary arteries using antibodies directed against the core proteins of these macromolecules. Versican immunostaining was prominent throughout the extracellular matrix (ECM) in regions of the vessels that contained abundant smooth-muscle cells, such as in diffuse intimal thickenings, fibrous caps, and in zones of loose, myxoid connective tissue. Versican also was present in smooth-muscle-rich thrombi and at borders of the lipid-rich cores of advanced atherosclerotic lesions. Biglycan immunostaining was observed in diffuse intimal thickenings, fibrous caps, and myxoid areas, but, unlike versican, it was abundant in the lipid-rich core of advanced plaques. However, biglycan immunostaining was absent in smooth-muscle cell-enriched thrombi. Decorin immunostaining paralleled biglycan immunostaining except that it was conspicuously absent in the myxoid areas of the plaque and markedly reduced in diffuse intimal thickenings. Both biglycan and decorin immunostaining were consistently associated with some of the microvessels in the thrombi and in advanced atherosclerotic plaques. Taken together, these results indicate that specific proteoglycans distribute to topographically defined regions of normal and atherosclerotic human coronary arteries and that these different distributions may indicate a diversity of functions in normal and pathologic processes of the arterial wall.

Collagen is reduced and disrupted in human aneurysms and dissections of ascending aorta

In ascending aorta aneurysms, there is an enlargement of the whole vessel, whereas aortic dissections (ADs) are characterized by the cleavage of the wall into 2 sheets at the external half. We searched if alterations in collagen could be related to these diseases. Sections of aortas from 14 case patients with acute dissections, 10 case patients with aneurysms, and 9 control subjects were stained with picrosirius. Slides were analyzed under polarized microscopy to evaluate the structure of collagen fibers. The proportion of collagen was calculated in each half of the medial layer by color detection in a computerized image analysis system. Collagen appearance under polarized light was consistent with collagenolysis. The mean collagen proportions at the inner and outer halves, respectively, were 0.50 +/- 0.13 and 0.40 +/- 0.08 in the control group, 0.20 +/- 0.10 and 0.18 +/- 0.12 in the AD group, and 0.33 +/- 0.12 and 0.19 +/- 0.12 in the aneurysm group. The AD (P < .01) and control (P = .04) groups had less collagen at the external half; no difference was found in the aneurysm group (P = .71). In both halves, there was less collagen in the case patients than in the control subjects (all P < .01), but at the internal half, the decrease was significantly greater in the case patients with aneurysms than in those with dissections (P = .03; at the external half, P = .99). Aortic dissections and aneurysms show a decrease in collagen content that could be related to a weakness of the wall underlying the diseases, but the locations of the decrease differ: in dissections, it is situated mostly at the external portion of the media (site of cleavage), whereas in aneurysms, it is more diffuse, consistent with the global enlargement.

Tissue diffusion and retention of metalloproteinases in ascending aortic aneurysms and dissections

Histopathological alterations in human aneurysms and dissections of the thoracic ascending aorta include areas of mucoid degeneration within the medial layer, colocalized with areas of cell disappearance and disruption of extracellular matrix elastic and collagen fibers. We studied the presence of matrix metalloproteinases in relation to their capacity to diffuse through the tissue or to be retained in areas of mucoid degeneration in aneurysms and dissections of the ascending aorta. Ascending aortas from 9 controls, 33 patients with aneurysms, and 14 with acute dissections, all collected at surgery, were analyzed. The morphological aspect was similar whatever the etiology or phenotypic expression of the pathological aortas, involving areas of extracellular matrix breakdown and cell rarefaction associated with mucoid degeneration. Release of proMMP-2, constitutively expressed by smooth muscle cells, was not different between controls and aneurysmal aortas, whereas the aneurysmal aortas released more of the active form. Release of pro and active MMP-9 was also similar between controls and aneurysmal aortas. Immunohistochemical staining of MMP-2 and MMP-9 was weak in both control and pathological aortas. In contrast, released MMP-7 (matrilysin) and MMP-3 (stromelysin-1) could not be detected in conditioned media but were present in tissue extracts with no detectable quantitative difference between controls and pathological aortas. Immunohistochemical staining of MMP-7 and MMP-3 revealed their retention in areas of mucoid degeneration, and semiquantitative evaluation of immunostaining showed more MMP-7 in pathological aortas than in controls. In conclusion, areas of mucoid degeneration, the hallmark of aneurysms, and dissections of thoracic ascending aortas, whatever their etiology, are not inert and can retain specific proteases.

Comparison between clinical and autopsy diagnoses in a cardiology hospital

Background: A few recent studies have evaluated diagnostic accuracy by comparison between clinical and autopsy diagnoses in a hospital specialising in cardiology. Methods: 406 consecutive autopsy cases during 2 years were studied. Patients were aged 47.4±28.4 years; 236 (58.1%) were men and 170 (41.9%) women. Diagnostic comparison was categorised in classes I to V (I, II, III and IV: discrepancy in decreasing order of importance regarding therapy and prognosis; V: concordance). Categorisation was ranked on the basis of the highest degree of discrepancy. Statistical analysis was performed with the Χ2 test and stepwise logistic regression. Results: Each age increase of 10 years added 16.2% to the risk of the diagnostic comparison to be categorised in classes I and II (major discrepancy) in comparison to classes III, IV and V (OR 1.16, 95% CI 1.07 to 1.27, p<0.001). By contrast, admission to intensive care units decreased the risk of categorisation in classes I and II by 47% (OR 0.53, 95% CI 0.32 to 0.85, p = 0.009). The most frequent diagnostic discrepancy occurred for pulmonary embolism: 30 out of 88 (34.1%) diagnoses in classes I and II. The concordance rate was 71.1% for acute myocardial infarction, 75% for aorta dissection, 73.1% for infective endocarditis and 35.2% for pulmonary embolism. Conclusion: Age and hospital ward influenced the distribution of diagnostic discrepancy or concordance between clinical and autopsy diagnoses. The lower discrepancy rate for myocardial infarction and infective endocarditis may be related to the fact that the study was carried out in a specialist hospital.

Acute Chagas' disease: immunohistochemical characteristics of T cell infiltrate and its relationship with T. cruzi parasitic antigens.

Objective — The present work analysed endomyocardial biopsies of patients with acute Chagas’ disease in order to evaluate the frequency and intensity of T. cruzi antigens, CD4+ and CD8+ T cells to determine the characteristics of this recurrent disease in Venezuela. Material and methods — Twelve endomyocardial biopsies of patients with Chagas’ disease, 12 to 51 years old, (7M and 5F) were analysed. T. cruzi antigens and CD4+ (helper) and CD8+ (cytotoxicsuppressor) T cells were detected by the immunoperoxidase technique.The presence and intensity of lymphocytic myocarditis was evaluated according to the degree of myocardial fibre injury caused by inflammatory infiltrate. Results — Myocarditis was present in 100% of the cases.The mean numbers of CD4+ T cell and CD8+ T cell were 11.00 (± 10.29); 14.69 (± 13.08) and the CD4/CD8 T cell ratio was 0.75. T. cruzi antigens were detected in 58%. There was a good correlation between the numbers of CD4 and CD8 T cells of each case and a lack of correlation with the amount of T. cruzi antigens. Conclusion — All patients with acute Chagas’ disease show some degree of myocarditis that seems to be directly related to the presence of parasitic antigens. Both CD4 and CD8 T cells participate in this process.We are following these patients to see if patients with severe myocarditis and more parasite antigens in the acute phase will develop chronic heart failure.