ABSTRACT
Objective To evaluate the predictive value of radiofrequency catheter ablation (RFCA) in patients with atrial fibrillation by measuring the left atrial structure and functional parameters with quantitative echocardiography.Methods One hundred and two patients with atrial fibrillation underwent radiofrequency ablation and 22 healthy cases as control group were enrolled in this study.Early diastolic strain(Se),global diastolic strain(Sg),late diastolic strain (Sa =Sg-Se),early diastolic strain rate (SRe),late diastolic strain rate(SRa),systolic strain rate (SRs) were measured.The standard deviations were calculated by time to peak of strain and strain rate.Left atrial maximum volume (LAVmax) and left atrial minimum volume (LAVmin) were measured.Left atrial stroke volume (LASV) and left atrial ejection fraction (LAEF) were calculated.The regression equation was obtained by binary logistic regression analysis.The individual probabilistic variables generated in the SPSS worksheet were selected to plot the multivariate ROC curve to determine the area undercurve (AUC) and the optimal cutoff point.Results In the group of paroxysmal atrial fibrillation:Sg,Se,Em decreased and TPSR-SD,TPSRs-SD increased significantly (P ＜0.05) in the relapsed patients;The logistic regression equation was P =1/[1 + e-(3.994+0.22×Se+0.115×Sg+0.04×TPSReSD-0.354×Em+0.02×TPSRsSD)].With P≥0.202 as thecut-off,the sensitivity and specificity of recurrence were the highest,88.9％ and 89.4％ respectively.In the group of persistent atrial fibrillation:the SRs,LAEF and LASV decreased and E/Em increased (P ＜0.05) in the relapsed patients.The logistic regression equation was P =1/[1 + e-(1.139-0.102LASV +0.348×E/Em-3.266×LAEF 0.417×SRs)].With P≥ 0.502 as thecut off,the sensitivity and specificity of recurrence were the highest,77.3％ and 79.2％ respectively.Conclusions Left atrial ultrasound quantitative analysis techniques to atrial fibrillation ablation recurrence have good predictive value.The recurrence of paroxysmal atrial fibrillation can be predicted by the strain rate and the standard deviation of time to peak of strain rate,and the persistent atrial fibrillation by LASV,LAEFand SRs.The multivariate analysis shows a higher predictive value.
ABSTRACT
No presente estudo, duas importantes situações foram abordadas no intuito de se melhor entender os mecanismos homeostáticos dos pressorreceptores na gênese da hipertrofia cardíaca em resposta à hipertensão renovascular: o efeito do tempo de clipe na artéria renal e o efeito dos níveis pressóricos e da variabilidade da pressão arterial. O curso temporal mostrou que, antes mesmo da instalação da hipertensão, há alteração da morfologia cardíaca, qual seja o desenvolvimento de uma hipertrofia ventricular excêntrica e, como forma de mecanismo compensatório, um aumento da expressão de algumas proteínas da homeostase do cálcio (fosfolambam fosforilada pela serina-16 e corrigido pelo fosfolambam total em 100% e fosfolambam fosforilado pela treonina-17 e corrigido pelo fosfolambam total em 54%). Uma vez instalada a hipertensão, observou-se um remodelamento ventricular esquerdo para o tipo concêntrico, com prejuízo da função diastólica e um desbalanço do sistema nervoso autonômico, com aumento da atividade simpática, observado pelo aumento da razão dos componentes de baixa freqüência (LF) e alta freqüência (HF) no tacograma (0,44 ± 0,10 vs. 0,20 ± 0,03 nos controles). A análise do efeito da pressão arterial e da variabilidade da pressão arterial mostrou uma correlação positiva com o grau de hipertrofia ventricular esquerda (r=0,76, p<0,01). A secção cirúrgica dos pressorreceptores somada à implantação do clipe na artéria renal mostrou adaptações cardiovasculares em níveis semelhantes (mesmo nível de hipertensão) e, por vezes maiores (modulação simpática para o coração e para os vasos, hipertrofia ventricular esquerda e disfunção diastólica), ao grupo cuja artéria renal foi estenosada e que permaneceu com os barorreceptores intactos. Estas respostas aconteceram num período de tempo três vezes menor na ausência do barorreflexo. Tais observações ressaltam o importante efeito homeostático do barorreflexo na gênese das respostas cardíacas adaptativas à hipertensão arterial.
In the present study, two important situations were observed to evaluate the role of the baroreceptors in the genesis of cardiac hypertrophy in response to hypertension: the effect of the time-course of the clip in the renal artery and the effect of the level of arterial blood pressure (ABP) and blood pressure variability (ABPV). The time-course evaluation showed that even before hypertension was installed, cardiac alterations could be observed, as a left ventricular eccentric hypertrophy. Compensatory mechanisms, such as an increase in some calcium homeosthatic proteins, could also be noticed (increase in phosphorilated phospholmaban at threonin-17 corrected by total phospholamban in 54% and increase in phosphorilated phospholmaban at serine-16 corrected by total phospholamban in 100%). However, once hypertension was established, left ventricle morphology changed to a concentric hypertrophy, accompanied by a diastolic dysfunction and enhanced sympathetic modulation, observed by relation between low-frequency component (LF) and high-frequency component (HF) at tachogram (0,44 ± 0,10 vs. 0,20 ± 0,03 in control group). ABP and ABPV analyses showed an important positive correlation with the degree of left ventricular hypertrophy (r=0,76, p<0,01). However, the absence of baroreceptors in one of the hypertensive groups, evoked the same cardiovascular alterations (same level of hypertension) or even worse (sympathetic modulation for heart and vessels, left ventricular hypertrophy and diastolic dysfunction) reached by the hypertensive baroreceptors-preserved group. These cardiovascular responses were observed in a period that correspond one third of time to the group with intact baroreflex. These observations lead us to conclude the importance of homeosthatic effects of the baroreflex in the genesis of cardiac responses to hypertension.