Assessment of a New Experimental Model of Isolated Right Ventricular Failure

We assessed a new experimental model of isolated right ventricular (RV) failure, achieved by means of intramyocardial injection of ethanol. RV dysfunction was induced in 13 mongrel dogs via multiple injections of 96% ethanol (total dose 1 mL/kg), all over the inlet and trabecular RV free walls. Hemodynamic and metabolic parameters were evaluated at baseline, after ethanol injection, and on the 14th postoperative day (POD). Echocardiographic parameters were evaluated at baseline, on the sixth POD, and on the 13th POD. The animals were then euthanized for histopathological analysis of the hearts. There was a 15.4% mortality rate. We noticed a decrease in pulmonary blood flow right after RV failure (P = 0.0018), as well as during reoperation on the 14th POD (P = 0.002). The induced RV dysfunction caused an increase in venous lactate levels immediately after ethanol injection and on the 14th POD (P < 0.0003). The echocardiogram revealed a decrease in the RV ejection fraction on the sixth and 13th PODs (P = 0.0001). There was an increased RV end-diastolic volume on the sixth (P = 0.0001) and 13th PODs (P = 0.0084). The right ventricle showed a 74% +/- 0.06% transmural infarction area, with necrotic lesions aged 14 days. Intramyocardial ethanol injection has allowed the creation of a reproducible and inexpensive model of RV failure. The hemodynamic, metabolic, and echocardiographic parameters assessed at different protocol times are compatible with severe RV failure. This model may be useful in understanding the pathophysiology of isolated right-sided heart failure, as well as in the assessment of ventricular assist devices.

Local renin-angiotensin system regulates left ventricular hypertrophy induced by swimming training independent of circulating renin: a pharmacological study

Introduction. This study addressed the role of the local renin-angiotensin system (RAS) in the left ventriular hypertropy (LVH) induced by swimming training using pharmacological blockade. Materials and methods. Female Wistar rats treated with enalapril maleate (60 mg.kg(-1).d(-1), n = 38), losartan (20 mg.kg(-1).d(-1), n = 36) or high salt diet (1% NaCl, n = 38) were trained by two protocols (T1: 60-min swimming session, 5 days per week for 10 weeks and T2: the same T1 protocol until the 8(th) week, then 9(th) week they trained twice a day and 10(th) week they trained three times a day). Salt loading prevented activation of the systemic RAS. Haemodynamic parameters, soleus citrate synthase (SCS) activity and LVH (left ventricular/body weight ratio, mg/g) were evaluated. Results. Resting heart rate decreased in all trained groups. SCS activity increased 41% and 106% in T1 and T2 groups, respectively. LVH was 20% and 30% in T1 and T2 groups, respectively. Enalapril prevented 39% of the LVH in T2 group (p < 0.05). Losartan prevented 41% in T1 and 50% in T2 (P < 0.05) of the LVH in trained groups. Plasma renin activity (PRA) was inhibited in all salt groups and it was increased in T2 group. Conclusions. These data provide evidence that the physiological LVH induced by swimming training is regulated by local RAS independent from the systemic, because the hypertrophic response was maintained even when PRA was inhibited by chronic salt loading. However, other systems can contribute to this process.

Quantitative Ventricular Neuroendoscopy Performed on the Third Ventriculostomy: Anatomic Study

BACKGROUND: One of the key elements for a successful endoscopic intervention in the ventricular system is the ability to recognize the anatomic structures and use them as a reference. OBJECTIVE: To measure the choroid plexus with endoscopy in the interventricular foramen, together with the structures on the third ventricle floor, and to compare these variables. METHODS: An observational prospective study was carried out on 37 brains of cadavers for which the cause of death was assessed at the Death Check Unit of the University of Sao Paulo in April 2008. This study was done on adults of both sexes with a rigid neuroendoscope. Endoscopic images were recorded, submitted for correction of distortion, and then measured. RESULTS: The measurements of the choroid plexus in the interventricular foramen, laterolateral distance of mammillary bodies, distance from the infundibular recess to the mammillary bodies, and area of the triangle in the tuber cinereum were 1.71 +/- 0.77 mm, 2.23 +/- 0.74 mm, 3.22 +/- 0.82 mm, and 3.69 +/- 2.09 mm(2), respectively. The ventricle floor was opaque in 84% of cases. The internal distance of mammillary bodies was absent in 89%. Associations between the translucent floor of the third ventricle and laterolateral distance of mammillary bodies, internal distance of mammillary bodies, and age were identified. CONCLUSION: Before this research, there was no record of the measurements of the choroid plexus in the interventricular foramen. The remaining variables of the present study show a greater number in normal brains compared with others.

Abnormalities in arterial-ventricular coupling in older healthy persons are attenuated by sodium nitroprusside

Chantler PD, Nussbacher A, Gerstenblith G, Schulman SP, Becker LC, Ferrucci L, Fleg JL, Lakatta EG, Najjar SS. Abnormalities in arterial-ventricular coupling in older healthy persons are attenuated by sodium nitroprusside. Am J Physiol Heart Circ Physiol 300: H1914-H1922, 2011. First published March 4, 2011; doi:10.1152/ajpheart.01048.2010.-The coupling between arterial elastance (E(A); net afterload) and lea ventricular elastance (E(LV); pump performance), known as E(A)/E(LV), is a key determinant of cardiovascular performance and shifts during exercise due to a greater increase in E(LV) versus E(A). This normal exercise-induced reduction in E(A)/E(LV) decreases with advancing age. We hypothesized that sodium. nitroprusside (SNP) can acutely ameliorate the age-associated deficits in E(A)/E(LV). At rest and during graded exercise to exhaustion, EA was characterized as end-systolic pressure/stroke volume and E(LV) as end-systolic pressure/end-systolic volume. Resting E(A)/E(LV): did not differ between old (70 +/- 8 yr. n = 15) and young (30 +/- 5 yr. n = 17) subjects because of a tandem increase in E(A) and E(LV) in older subjects. During peak exercise, a blunted increase in E(LV) in old (7.8 +/- 3.1 mmHg/ml) versus young (11.4 +/- 6.5 mmHg/ml) subjects blunted the normal exercise-induced decline in E(A)/E(LV) in old (0.25 +/- 0.11) versus young (0.16 +/- 0.05) subjects. SNP administration to older subjects lowered resting E(A)/E(LV) by 31% via a reduction E(A) (10%) and an increase in E(LV) (47%) and lowered peak exercise E(A)/E(LV) (36%) via an increase in E(LV) (68%) without a change in E(A). Importantly, SNP attenuated the age-associated deficits in E(A)/E(LV) and E(LV) during exercise, and at peak exercise E(A)/E(LV) in older subjects on drug administration did not differ from young subjects without drug administration. In conclusion, some age-associated deficiencies in E(A)/E(LV), E(A), and E(LV), in older subjects can be acutely abolished by SNP infusion. This is relevant to common conditions in older subjects associated with a significant impairment of exercise performance such as frailty or heart failure with preserved ejection fraction.

Changes in Myocardial Perfusion Correlate With Deterioration of Left Ventricular Systolic Function in Chronic Chagas` Cardiomyopathy

OBJECTIVES This study aimed at analyzing the association between myocardial perfusion changes and the progression of left ventricular systolic dysfunction in patients with chronic Chagas` cardiomyopathy (CCC). BACKGROUND Pathological and experimental studies have suggested that coronary microvascular derangement, and consequent myocardial perfusion disturbance, may cause myocardial damage in CCC. METHODS Patients with CCC (n = 36, ages 57 +/- 10 years, 17 males), previously having undergone myocardial perfusion single-positron emission computed tomography and 2-dimensional echocardiography, prospectively underwent a new evaluation after an interval of 5.6 +/- 1.5 years. Stress and rest myocardial perfusion defects were quantified using polar maps and normal database comparison. RESULTS Between the first and final evaluations, a significant reduction of left ventricular ejection fraction was observed (55 +/- 11% and 50 +/- 13%, respectively; p = 0.0001), as well as an increase in the area of the perfusion defect at rest (18.8 +/- 14.1% and 26.5 +/- 19.1%, respectively; p = 0.0075). The individual increase in the perfusion defect area at rest was significantly correlated with the reduction in left ventricular ejection fraction (R = 0.4211, p = 0.0105). Twenty patients with normal coronary arteries (56%) showed reversible perfusion defects involving 10.2 +/- 9.7% of the left ventricle. A significant topographic correlation was found between reversible defects and the appearance of new rest perfusion defects at the final evaluation. Of the 47 segments presenting reversible perfusion defects in the initial study, 32 (68%) progressed to perfusion defects at rest, and of the 469 segments not showing reversibility in the initial study, only 41 (8.7%) had the same progression (p < 0.0001, Fisher exact test). CONCLUSIONS In CCC patients, the progression of left ventricular systolic dysfunction was associated with both the presence of reversible perfusion defects and the increase in perfusion defects at rest. These results support the notion that myocardial perfusion disturbances participate in the pathogenesis of myocardial injury in CCC. (J Am Coll Cardiol Img 2009;2:164-72) (c) 2009 by the American College of Cardiology Foundation

Sustained Ventricular Tachycardia Is Associated with Regional Myocardial Sympathetic Denervation Assessed with (123)I-Metaiodobenzylguanidine in Chronic Chagas Cardiomyopathy

Cardiac sympathetic denervation and ventricular arrhythmia are frequently observed in chronic Chagas cardiomyopathy (CCC). This study quantitatively evaluated the association between cardiac sympathetic denervation and sustained ventricular tachycardia (SVT) in patients with CCC. Methods: We prospectively investigated patients with CCC and left ventricular ejection fraction (LVEF) greater than 35% with SVT (SVT group: n = 5 15; mean age +/- SD, 61 +/- 8 y; LVEF, 51% +/- 8%) and patients without SVT (non-SVT group: n = 11; mean age +/- SD, 55 +/- 10 y; LVEF, 57% +/- 10%). Patients underwent myocardial scintigraphy with (123)I-metaiodobenzylguanidine ((123)I-MIBG) for the evaluation of sympathetic innervation and resting perfusion with (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) for the evaluation of myocardial viability. A visual semiquantitative score was attributed for regional uptake of each radiotracer using a 17-segment left ventricular segmentation model (0, normal; 4, absence of uptake). A mismatch defect was defined as occurring in segments with a 99mTc-MIBI uptake score of 0 or 1 and a (123)I-MIBG score of 2 or more. Results: Compared with the non-SVT group, the SVT group had a similar (99m)Tc-MIBI summed score (6.9 +/- 7.5 vs. 4.4 +/- 5.2, respectively, P = 0.69) but a higher (123)I-MIBG summed score (10.9 +/- 7.8 vs. 22.4 +/- 9.5, respectively, P = 0.007) and a higher number of mismatch defects per patient (2.0 +/- 2.2 vs. 7.1 +/- 2.0, respectively, P < 0.0001). The presence of more than 3 mismatch defects was strongly associated with the presence of SVT (93% sensitivity, 82% specificity; P = 0.0002). Conclusion: In CCC, the amount of sympathetically denervated viable myocardium is associated with the occurrence of SVT. Myocardial sympathetic denervation may participate in triggering malignant ventricular arrhythmia in CCC patients with relatively well-preserved ventricular function.

Predictors of Mortality in Patients with Chagas` Cardiomyopathy and Ventricular Tachycardia Not Treated with Implantable Cardioverter-Defibrillators

Methods: We assessed the outcome of 56 patients with Chagas` cardiomyopathy ([31 men]; mean age of 55 years; mean left ventricular ejection fraction [LVEF] 42%) presenting with either sustained ventricular tachycardia (VT) or nonsustained VT (NSVT), before therapy with implantable cardioverter-defibrillator was available at our center. Results: Over a mean follow-up of 38 +/- 16 months (range, 1-61 months), 16 patients (29%) died, 11 due to sudden cardiac death (SCD), and five from progressive heart failure. Survivors and nonsurvivors had comparable baseline characteristics, except for a lower LVEF (46 +/- 7% vs 31 +/- 9%, P < 0.001) and a higher New York Heart Association class (P = 0.003) in those who died during follow-up. Receiver-operator characteristic curve analysis showed that an LVEF cutoff value of 38% had the best accuracy for predicting all-cause mortality and an LVEF cutoff value of 40% had the best accuracy for prediction of SCD. Using the multivariate Cox regression analysis, LVEF < 40% was the only predictor of all-cause mortality (hazard ratio [HR] 12.22, 95% confidence interval [CI] 3.46-43.17, P = 0.0001) and SCD (HR 6.58, 95% CI 1.74-24.88, P = 0.005). Conclusions: Patients with Chagas` cardiomyopathy presenting with either sustained VT or NSVT run a major risk for mortality when had concomitant severe or even moderate LV systolic dysfunction. (PACE 2011; 54-62).

Validation of ACB in vitro and in vivo as a biomagnetic method for measuring stomach contraction

Background The aim of this study was to validate a biomagnetic method (alternate current biosusceptometry, ACB) for monitoring gastric wall contractions in rats. Methods In vitro data were obtained to establish the relationship between ACB and the strain-gauge (SG) signal amplitude. In vivo experiments were performed in pentobarbital-anesthetized rats with SG and magnetic markers previously implanted under the gastric serosa or after ingestion of magnetic material. Gastric motility was quantified from the tracing amplitudes and frequency profiles obtained by Fast Fourier Transform. Key Results The correlation between in vitro signal amplitudes was strong (R = 0.989). The temporal cross-correlation coefficient between the ACB and SG signal amplitude was higher (P < 0.0001) in the postprandial (88.3 +/- 9.1 V) than in the fasting state (31.0 +/- 16.9 V). Irregular signal profiles, low contraction amplitudes, and smaller signal-to-noise ratios explained the poor correlation between techniques for fasting-state recordings. When a magnetic material was ingested, there was also strong correlation in the frequency and signal amplitude and a small phase-difference between the techniques. The contraction frequencies using ACB were 0.068 +/- 0.007 Hz (postprandial) and 0.058 +/- 0.007 Hz (fasting) (P < 0.002) and those using SG were 0.066 +/- 0.006 Hz (postprandial) and 0.059 +/- 0.008 Hz (fasting) (P < 0.005). Conclusions & Inferences In summary, ACB is reliable for monitoring gastric wall contractions using both implanted and ingested magnetic materials, and may serve as an accurate and sensitive technique for gastrointestinal motility studies.

Endothelin-1 Induces Contraction of Female Rat Internal Pudendal and Clitoral Arteries through ET(A) Receptor and Rho-Kinase Activation

Introduction. Endothelin-1 (ET-1), a potent vasoconstrictor peptide, acts mainly through the Gprotein-coupled ET(A) receptor (ET(A)R). Increased vascular ET-1 production and constrictor sensitivity have been observed in various cardiovascular diseases, including hypertension, as well as erectile dysfunction. The internal pudendal artery (IPA) supplies blood to the vagina and clitoris. Inadequate blood flow through the IPA may lead to insufficient vaginal engorgement and clitoral tumescence. Aim. Characterize the effects of ET-1 on the IPA and clitoral artery (CA). Methods. IPA and CA from female Sprague Dawley rats (225-250 g) were mounted in myograph chambers. Arterial segments were submitted to increasing concentrations of ET-1 (10-10-10-6 M). Segments were incubated with the ET(A)R antagonist, atrasentan (10-8 M) or the Rho-kinase inhibitor, Y-27632 (10-6 M) 30 minutes prior to agonist exposure. All E(max) values are expressed as % KCl-induced maximal contraction. ET(A)R, RhoA, and Rho-kinase expression from IPA was evaluated by Western blot. mRNA of preproET-1, ET(A)R, ET(B)R, RhoA, and Rho-kinase were measured by real time PCR. Main Outcome Measures. ET-1 constrictor sensitivity in IPA and CA, protein expression and messenger RNA levels of ET-1-mediated constriction components. Results. ET-1 concentration-dependently contracted IPA (% Contraction and pD2, respectively: 156 +/- 18, 8.2 +/- 0.1) and CA (163 +/- 12, 8.8 +/- 0.08), while ET(A)R antagonism reduced ET-1-mediated contraction (IPA: 104 +/- 23, 6.4 +/- 0.2; CA: 112 +/- 17, 6.6 +/- 0.08). Pretreatment with Y-27632 significantly shifted ET-1 pD2 in IPA (108 +/- 24, 7.9 +/- 0.1) and CA (147 +/- 58 and 8.0 +/- 0.25). Protein expression of ET(A)R, ET(B)R, RhoA, and Rho-kinase were detected in IPA. IPA and CA contained preproET-1, ET(A)R, ET(B)R, RhoA, and Rho-kinase message. Conclusion. We observed that the IPA and CA are sensitive to ET-1, signaling through the ET(A)R and Rho-kinase pathway. These data indicate that ET-1 may play a role in vaginal and clitoral blood flow and may be important in pathologies where ET-1 levels are elevated. Allahdadi KJ, Hannan JL, Tostes RC, and Webb RC. Endothelin-1 induces contraction of female rat internal pudendal and clitoral arteries through ETA receptor and Rho-kinase activation. J Sex Med 2010;7:2096-2103.

Uridine adenosine tetraphosphate-induced contraction is increased in renal but not pulmonary arteries from DOCA-salt hypertensive rats

Matsumoto T, Tostes RC, Webb RC. Uridine adenosine tetraphosphate-induced contraction is increased in renal but not pulmonary arteries from DOCA-salt hypertensive rats. Am J Physiol Heart Circ Physiol 301: H409-H417, 2011. First published May 6, 2011; doi:10.1152/ajpheart.00084.2011.-Uridine adenosine tetraphosphate (Up(4)A) was reported as a novel endothelium-derived contracting factor. Up(4)A contains both purine and pyrimidine moieties, which activate purinergic (P2)X and P2Y receptors. However, alterations in the vasoconstrictor responses to Up(4)A in hypertensive states remain unclear. The present study examined the effects of Up(4)A on contraction of isolated renal arteries (RA) and pulmonary arteries (PA) from DOCA-salt rats using isometric tension recording. RA from DOCA-salt rats exhibited increased contraction to Up(4)A versus arteries from control uninephrectomized rats in the absence and presence of N(G)-nitro-L-arginine (nitric oxide synthase inhibitor). On the other hand, the Up(4)A-induced contraction in PA was similar between the two groups. Up(4)A-induced contraction was inhibited by suramin (nonselective P2 antagonist) but not by diinosine pentaphosphate pentasodium salt hydrate (Ip5I; P2X(1) antagonist) in RA from both groups. Furthermore, 2-thiouridine 5`-triphosphate tetrasodium salt (2-Thio-UTP; P2Y(2) agonist)-, uridine-5`-(gamma-thio)-triphosphate trisodium salt (UTP gamma S; P2Y(2)/P2Y(4) agonist)-, and 5-iodouridine-5`-O-diphosphate trisodium salt (MRS 2693; P2Y(6) agonist)-induced contractions were all increased in RA from DOCA-salt rats. Protein expression of P2Y(2)-, P2Y(4)-, and P2Y(6) receptors in RA was similar between the two groups. In DOCA-salt RA, the enhanced Up(4)A-induced contraction was reduced by PD98059, an ERK pathway inhibitor, and Up(4)Astimulated ERK activation was increased. These data are the first to indicate that Up(4)A-induced contraction is enhanced in RA from DOCA-salt rats. Enhanced P2Y receptor signaling and activation of the ERK pathway together represent a likely mechanism mediating the enhanced Up(4)A-induced contraction. Up(4)A might be of relevance in the pathophysiology of vascular tone regulation and renal dysfunction in arterial hypertension.

Growth after ventricular septal defect repair: does defect size matter? A 10-year experience

Aim: To evaluate whether the ventricular septal defect (VSD) size, along with the degree of preoperative growth impairment and age at repair, may influence postoperative growth, and if VSD size can be useful to identify children at risk for preoperative failure to thrive. Methods: Sixty-eight children submitted to VSD repair in a Brazilian tertiary-care institution were evaluated. Weight and height measurements were converted to Z-scores. Ventricular septal defect size was normalized by dividing it by the aortic root diameter (VSD/Ao ratio). Results: Twenty-six patients (38%) had significantly low weight-for-height, 10 patients (15%) had significantly low height-for-age and 13 patients (19%) had both conditions at repair. Catch-up growth occurred in 82% of patients for weight-for-age, in 75% of patients for height-for-age and in 89% of patients for weight-for-height. Weight-for-height Z-scores at surgery were significantly lower in patients who underwent repair before 9 months of age. The VSD/Ao ratio did not associate with any other data. On multivariate analysis, weight-for-age Z-scores and age at surgery were independent predictors of long-term weight and height respectively. Conclusion: The VSD/Ao ratio was not a good predictor of preoperative failure to thrive. Most patients had preoperative growth impairment and presented catch-up growth after repair. Preoperative growth status and age at surgery influenced long-term growth.

The ACB technique: a biomagentic tool for monitoring gastrointestinal contraction directly from smooth muscle in dogs

The aim of this paper was to verify whether AC biosusceptometry (ACB) is suitable for monitoring gastrointestinal (GI) contraction directly from smooth muscle in dogs, comparing with electrical recordings simultaneously. All experiments were performed in dogs with magnetic markers implanted under the serosa of the right colon and distal stomach, and their movements were recorded by ACB. Monopolar electrodes were implanted close to the magnetic markers and their electric potentials were recorded by electromyography (EMG). The effects of neostigmine, hyoscine butylbromide and meal on gastric and colonic parameters were studied. The ACB signal from the distal stomach was very similar to EMG; in the colonic recordings, however, within the same low-frequency band, ACB and EMG signals were characterized by simultaneity or a widely changeable frequency profile with time. ACB recordings were capable of demonstrating the changes in gastric and colonic motility determined by pharmacological interventions as well as by feeding. Our results reinforce the importance of evaluating the mechanical and electrical components of motility and show a temporal association between them. ACB and EMG arecomplementary for studying motility, with special emphasis on the colon. ACB offers an accurate method for monitoring in vivo GI motility.

Comparisons of the release of vasodilator substances from left and right cardiac chambers of the isolated perfused rabbit heart: Implications for intraventricular thrombus formation

Prostacyclin (PgI(2)) and endothelium-derived nitric oxide (EDNO) are produced by the arterial and venous endothelium. In addition to their vasodilator action on vascular smooth muscle, both act together to inhibit platelet aggregation and promote platelet disaggregation. EDNO also inhibits platelet adhesion to the endothelium. EDNO and PgI(2) have been shown to be released from the cultured endocardial cells. In this study, we examined the release of vasoactive substances from the intact endocardium by using isolated rabbit hearts perfused with physiological salt solution (95% O(2)/5% CO(2), T = 37 degrees C). The right and left cardiac chambers were perfused through separate constant-flow perfusion loops (physiological salt solution, 8 ml min(-1)). Effluent from left and right cardiac, separately, was bioassayed on canine coronary artery smooth muscle, which had been contracted with prostaglandin F(2 alpha_)(2 x 10(-6) M) and no change in tension was exhibit. However, addition of calcium ionophore A23187 (10(-6) M) to the cardiac chambers` perfusion line induced vasodilation of the bioassay coronary ring, 61.4 +/- 7.4% versus 70.49 +/- 6.1% of initial prostaglandin F(2 alpha) contraction for the left and right cardiac chambers perfusate, respectively (mean +/- SEM, n = 10, p > 0.05). Production of vasodilator was blocked totally in the left heart but, only partially blocked in the right heart by adding indomethacin (10(-5) M) to the perfusate, respectively, 95.2 +/- 2.2% versus 41.5 +/- 4.8% (mean +/- SEM, n = 10, p < 0.05). 6-Keto prostaglandin F(1 alpha), measured in the endocardial superfusion effluent was also higher for the left cardiac chambers than for the right at the time of stimulation with the A23187, respectively, 25385.88 +/- 5495 pg/ml (n = 8) versus 13,132.45 +/- 1839.82 pg/ml (n = 8), (p < 0.05). These results showed that cyclooxygenase pathway plays major role in generating vasoactive substances for the left cardiac chamber endocardium; while it is not the main pathway for the right ventricular endocardium at which EDNO and PgI(2) Could act together and potentiate their antithrombogenic activities in isolated perfused rabbit heart. This may be an explanation for the intraventricular thrombus mostly seen in left ventricle rather than in right ventricle as a complication of myocardial infarction. (C) 2009 Elsevier Inc. All rights reserved.

Matrix metalloproteinase 9 gene haplotypes affect left ventricular hypertrophy in hypertensive patients

Background: Matrix metalloproteinases (MMPs) are involved in cardiac remodeling and are encoded by genes showing genetic polymorphisms that have functional implications. We examined whether MMP-9 genetic polymorphisms are associated with hypertension and with left ventricular (LV) remodeling in hypertensive patients. Methods: We studied 173 hypertensive patients and 137 age, race and gender matched healthy controls. Heart echocardiography was performed in all patients and the following MMP-9 genetic polymorphisms were analyzed: C-(1562)T (rs3918242). -90 (CA)(14-24) (rs2234681) and Q279R (rs17576). Haplo.stats analysis was used to assess whether MMP-9 haplotypes are associated with hypertension. Linear regression analysis was performed to assess whether MMP-9 haplotypes affect LV mass index (LVMI) and other echocardiography parameters. Results: MMP-9 90 (CA)14-24 ""HH"" genotype (H allele defined by number of CA repeats >= 21) was associated with hypertension (P = 0.0085; OR = 2.321, 95% confidence interval = 1.250 to 4.309). While one MMP-9 haplotype (""C. H, Q"") protects against LVMI and end-diastolic diameter increases due to remodeling (P = 0.0490 and P = 0.0367), another MMP-9 haplotype apparently has detrimental effects over both parameters in hypertensive patients (""T, H. Q"", P = 0.0015 and P = 0.0057. respectively). Conclusion: Genetic polymorphisms in MMP-9 gene may modify the susceptibility of hypertensive patients to LV remodeling. Further studies are necessary to examine whether these polymorphisms affect clinical events in hypertensive patients. (C) 2010 Elsevier B.V. All rights reserved.

Focal and linear endocardial and epicardial catheter-based cryoablation of normal and infarcted ventricular tissue

Background: This study of a chronic porcine postinfarction model examined whether linear epicardial cryoablation was capable of creating large, homogenous lesions in regions of the myocardium including scarred ventricle. Endocardial and epicardial focal cryolesions were also compared to determine if there were significant differences in lesion characteristics. Methods: Eighty focal endocardial and 28 focal epicardial cryoapplications were delivered to eight normal caprine and four normal porcine ventricular myocardium, and 21 linear cryolesions were applied along the border of infarcted epicardial tissue in a chronic porcine infarct model in six swines. Results: Focal endocardial cryolesions in normal animals measured 9.7 +/- 0.4 mm (length) by 7.3 +/- 1.4 mm (width) by 4.8 +/- 0.2 mm (depth), while epicardial lesions measured 10.2 +/- 1.4 mm (length) by 7.7 +/- 2 mm (width) by 4.6 +/- 0.9 mm (depth); P > 0.05. Linear epicardial cryolesions in the chronic porcine infarct model measured 36.5 +/- 7.8 mm (length) by 8.2 +/- 1.3 mm (width) by 6.0 +/- 1.2 mm (depth). The mean depth of linear cryolesions applied to the border of the infarct scar was 7 +/- 0.7 mm, as measured by magnetic resonance imaging. Conclusions:Cryoablation can create deep lesions when delivered to the ventricular epicardium. Endocardial and epicardial cryolesions created by a focal cryoablation catheter are similar in size and depth. The ability to rapidly create deep linear cryolesions may prove to be beneficial in substrate-based catheter ablation of ventricular arrhythmias.