Miocardiopatia diabética em diabéticos sem comorbidades / Diabetes cardiomyopathy in diabetic patients without comorbidities

A miocardiopatia diabética tem-se afirmado como diagnóstico etiológico de insuficiência cardíaca. No entanto, a elevada frequência de comorbidades, no doente diabético, torna difícil a distinção da contribuição da alteração do metabolismo da glicose na fisiopatologia da insuficiência cardíaca. Objectivo: Estudar a função ventricular esquerda sistólica e diatólica em diabéticos sem comorbidades, com ecocardiografia convencional e Doppler tissular. Métodos: Foram estudados 23 doentes, com idade média de 53 + - 15 anos, sendo 10 mulheres, todos diabéticos, com pelo menos 5 anos de evolução e sem história prévia de insuficiência cardíaca, doença coronária ou hipertensão arterial grave. O grupo controle foi constituído por 18 doentes pareados para sexo e idade. A função sistólica foi avaliada através da fração de ejeção e da V máx da onda A, determinada por Doppler tissular, com amostras nos segmentos septal, lateral, inferior e anterior do anel mitral. A função diastólica foi avaliada pela razão E/A, tempo de desaceleração do fluxo transmitral (Doppler espectral pulsado), pela V máx d onda 'E, razão 'E/A' e 'E/'E obtida por meio do Doppler tissular, nos quatros segmentos anteriormente referidos. Foram avaliaddas as diferenças...

Predictors of response to cardiac resynchronization therapy--importance of left ventricular dyssynchrony.

BACKGROUND: Cardiac resynchronization therapy (CRT) is currently used in selected patients with dilated cardiomyopathy and heart failure. However, 30% of patients do not respond to CRT when selection is based on clinical and electrocardiographic criteria. Left ventricular dyssynchrony can be evaluated by tissue Doppler imaging and it has been described as a useful precdictor of response to CRT. OBJECTIVE: To evaluate whether left ventricular dyssynchrony, as measured by tissue Doppler imaging, can be used to predict response to CRT. METHODS: 23 consecutive patients (age 67 +/- 10 years, 13 male) with heart failure refractory to medical therapy and who underwent CRT were studied. Before and six months after the procedure, various characteristics - clinical (including NYHA functional class), electrocardiographic (QRS interval) and echocardiographic (left ventricular ejection fraction [EF] and respective volumes)--were evaluated. In addition, pulsed wave tissue Doppler imaging was used to assess the time interval (QS) between the beginning of the QRS complex and the beginning of the systolic wave on the Doppler signal, in the basal segments of the septal, lateral, anterior and inferior walls. Left ventricular dyssynchrony was quantified as the difference between the maximum and minimum QS interval (QS(max-min)). The patients were divide into two groups: responders, if functional class improved by at least one and EF increased by more than 10%, and non-responders for the remainder. Differences between groups were assessed and predictors of response to CRT were determined. RESULTS: CRT improved functional class by at least one in 87% of patients and EF improved from 21 +/- 6 to 33 +/- 9% (p < 0.001). QS(max-min) was reduced from 80 +/- 38 to 38 +/- 14 ms (p < 0.001). In 15 patients (65%), classified as responders, there was an improvement in functional class and an increase in EF of more than 10%. There were no differences between groups, except for QS(max-min). Patients in the responder group had greater left ventricular dyssynchrony (QS(max-min) 94 +/- 39 vs. 54 +/- 16 ms, p = 0.002). QSmix-min was an independent predictor of response to CRT and a cut-off of 60 ms identified responders with a sensitivity of 87% and specificity of 75%. CONCLUSION: Despite the good results achieved with CRT, about one third of patients do not benefit from it. Left ventricular dyssynchrony can be quantified by tissue Doppler imaging using QS(max-min) and values greater than 60 ms can identify responders to CRT.

Cardiac resynchronization therapy with sequential biventricular pacing: impact of echocardiography guided VV delay optimization on acute results.

BACKGROUND: Cardiac resynchronization therapy (CRT) improves left ventricular synchrony as evaluated by tissue Doppler imaging (TDI), leading to improved left ventricular performance and reverse remodeling. New CRT devices enable programming of left and right VV delay. The aim of this study was to determine whether sequential biventricular (BiV) pacing by echo-guided programming of VV delay would enhance the response to CRT. METHODS: 15 consecutive patients with severe heart failure and left bundle branch block underwent CRT by BiV device implantation. They were studied with conventional and TDI echo the day before implantation. Left ventricular ejection fraction (LVEF) was determined, and the electromechanical delay (QS), defined as the time interval from the beginning of the QRS to the S wave in pulsed TDI, was assessed in each of the four left ventricular basal segments. The dyssynchrony index was calculated as the difference between the longest and shortest electromechanical delay (QS(max-min)). The parameters were re-evaluated the day after implantation during simultaneous BiV pacing and with seven different VV delays. The optimal VV delay was determined by finding the VV interval corresponding to the maximum aortic velocity time interval (VTI). RESULTS: QS(max-min) decreased from 85.3 +/- 27.0 msec to 46.7 +/- 23.0 msec (p = 0.0002), LVEF increased from 21.7 +/- 7.3% to 30.0 +/- 7.7% (p = 0.0001) and aortic VTI increased from 12.7 +/- 3.6 cm to 15.2 +/- 4.0 cm (p < 0.0001), with simultaneous BiV pacing. The VV intervals were programmed as follows: LV pre-excitation by 10 msec in five patients, 20 msec in three, 30 msec in two, and 40 msec in three; and RV pre-excitation by 10 msec in one and by 20 msec in one. The maximal aortic VTI obtained with VV delay programming increased from 15.2 +/- 4.0 cm to 17.7 +/- 4.0 cm (p = 0.0005). During optimized sequential BiV pacing, QS(max-min) further decreased from 46.7 +/- 23.0 msec to 30.6 +/- 21.0 msec (p = 0.02) and LVEF further increased from 30.0 +/- 7.7% to 35.0 +/- 7.7% (p = 0.0003). CONCLUSIONS: Sequential BiV pacing with VV delay optimized by evaluation of aortic VTI enhanced the response to CRT with additional improvements in left ventricular synchrony and left ventricular function compared to simultaneous CRT.

Transesophageal echocardiography-guided cardioversion of atrial fibrillation. Selection of a low-risk group for immediate cardioversion.

INTRODUCTION: In patients (pts) with atrial fibrillation (AF) of more than 48 hours' duration, electrical cardioversion (ECV) should only be performed after 3 weeks of effective anticoagulation. Transesophageal echocardiography (TEE) allows earlier ECV; however, despite exclusion of thrombi in the atrium and left atrial appendage (LAA), cases of thromboembolism related to ECV have been documented in AF. To define a low-risk group for cardioversion without previous anticoagulation, pts were selected for immediate ECV if no thrombi or dynamic spontaneous echo contrast (auto-contrast) were found after TEE and if LAA velocity was more than 0.25 m/sec. METHODS AND RESULTS: We performed TEE in 31 consecutive pts referred for ECV for AF of more than 48 hours' duration and without previous anticoagulation. After TEE the pts eligible for immediate ECV began anticoagulation with low molecular weight heparin (enoxaparin), subcutaneously in therapeutic doses, together with warfarin immediately before cardioversion. Enoxaparin was continued until an INR of over 2 was reached. Based on the TEE findings, the pts were divided in 2 groups: immediate ECV, group A, 20 pts with a mean age of 62 +/- 13 years, 6 female; and conventional therapy with warfarin before ECV, group B, 11 pts, mean age of 67 +/- 10 years (p < 0.05), 2 female. None of the pts in either group had mitral stenosis or previous episodes of thromboembolism. The mean transverse diameter of the left atrium in the 31 pts was 47 +/- 4.5 mm, without statistically significant differences between the 2 groups. Of the 11 pts in group B, 3 had a thrombus in the LAA, 6 dynamic spontaneous echo contrast and the remainder LAA velocities of less than 0.25 m/sec. ECV was achieved in all the pts, with no complications. Oral anticoagulation was maintained for at least a month. At one month, sinus rhythm was maintained in 75% of group A and 45% of group B (p < 0.01). CONCLUSION: In pts with AF of more than 48 hours' duration and no previous history of thromboembolism, the use of our exclusion criteria during TEE enabled stratification of a low-risk population for immediate ECV, which was accomplished effectively and safely in 2/3 of the pts. This strategy is associated with early symptomatic improvement, and may contribute to maintenance of sinus rhythm after one month, which was significantly better than in the pts who had prolonged therapy with warfarin before ECV, despite the differences found in age and left ventricular function.

Effects of cardiac resynchronization therapy on right ventricular function--evaluation with tissue Doppler echocardiography.

INTRODUCTION AND OBJECTIVE: Ventricular resynchronization therapy improves cardiac function in patients (pts) with dilated cardiomyopathy and intraventricular conduction disturbances. The effects of ventricular resynchronization on right ventricular function have been poorly studied. Tricuspid annular motion can be studied with tissue Doppler echocardiography, which enables quantitative assessment of right ventricular function. The aim of this study was to evaluate the effects of ventricular resynchronization on right ventricular function with pulsed tissue Doppler. PATIENTS: We studied ten pts, eight male, mean age 65 +/- 10 years, with dilated cardiomyopathy, intraventricular conduction disturbances and heart failure, New York Heart Association functional class III or IV. Five pts had coronary artery disease and the others idiopathic dilated cardiomyopathy. All pts had an implanted cardioverter-defibrillator with ventricular resynchronization. METHODS: Before and one month after device implantation right ventricular function was evaluated with pulsed wave tissue Doppler study of tricuspid annular motion. The maximum velocity of the S wave (MV-S), E wave (MV-E), and A wave (MV-A), E/A ratio, isovolumetric contraction time (IVCT) and ejection time (ET) were determined. Right ventricular size and left ventricular ejection fraction (EF) were measured. Functional class before and after implantation was assessed. RESULTS: MV-S, MV-E and MV-A did not change significantly. The E/A ratio decreased significantly (p = 0.017). There were no differences in IVCT and ET, nor in right ventricular size before and after resynchronization. EF improved in all but one patient (p = 0.003). All pts had an improvement in functional class, except the one without increased EF. CONCLUSIONS: Ventricular resynchronization therapy does not appear to have a deleterious effect on right ventricular function in pts with dilated cardiomyopathy and intraventricular conduction disturbances. The main beneficial effect of this type of therapy appears to be improvement in left ventricular function.

Tissue Doppler echocardiography for evaluation of patients with ventricular resynchronization therapy.

INTRODUCTION AND OBJECTIVE: Ventricular resynchronization therapy optimizes cardiac function and induces reverse remodeling of the left ventricle (LV) in patients (pts) with dilated cardiomyopathy and intraventricular conduction disturbances. Improvement of LV mechanical synchrony seems to be the predominant mechanism. There is a growing interest in objective quantification of desynchronization. This study aims to evaluate the effect of ventricular resynchronization therapy on LV remodeling and on LV desynchronization, assessed by tissue Doppler echocardiography. PATIENTS: We studied ten pts, eight male, mean age 65 +/- 10 years, with dilated cardiomyopathy, intraventricular conduction disturbances and heart failure, New York Heart Association functional class III or IV. Five pts had coronary artery disease and the others idiopathic dilated cardiomyopathy. All pts had an implanted cardioverter, defibrillator with cardiac resynchronization therapy. The LV pacing electrode was placed in the lateral or posterolateral vein. METHODS: Before and one month after resynchronization therapy the following parameters were measured with conventional Doppler echocardiography: LV end-diastolic (LVd) and end-systolic (LVs) size, ejection fraction (EF) and mitral regurgitation (MR) area. For diastolic function the maximum velocity of the E wave (MV-E) and A wave (MV-A), E/A ratio, LV filling time (LV-FT) and isovolumetric relaxation time (IVRT) were meadured. Mitral longitudinal motion was studied with pulsed tissue Doppler. Maximum velocity of the systolic S wave (MV-S) and isovolumetric contraction time (IVCT) were measured in the tissue Doppler curve of the septum and lateral, inferior and anterior walls. To evaluate the degree of desynchronization the RV index was calculated for each patient, based on the difference between the maximum and minimum IVCT, normalized for the maximum IVCT. RESULTS: There was a significant reduction in LVd and MR. EF increased significantly (p = 0.003). There were no differences in diastolic function parameters. MV-S did not increase significantly. IVCT increased significantly at the lateral wall (p = 0.037). The RV index demonstrated a significant reduction in ventricular desynchronization (p = 0.001). CONCLUSIONS: Ventricular resynchronization therapy induces reverse remodeling and improves LV function in selected pts. Improvement of mechanical LV synchrony seems to be the predominant mechanism. Ventricular desynchronization can be measured by tissue Doppler echocardiography.