Efeitos agudos da ibopamina sobre a mêcanica ea contralidade ventricular esquerda em Pacientes com Cardiomiopatia dilatada idiopática / Acute Effects of Ibopamine on Left Ventricular Mechanics and Contractility in Patients with Idiopathic Dilated Cardiomyopathy

RESUMO

OBJETIVO - Avaliar os efeitos agudos da ibopamina (IBO) sobre a mecânica e a contrabilidade miocárdica em pacientes com insuficiência cardíaca congestiva (ICC)refratária secundária à cardiomiopatia dilatada idiopática.MÉTODOS- Foram estudados 10 pacientes (idade= 43+-7anos) do sexo masculino, em ritmo sinusal, com cardiomiopatia dilatada idiopática e ICC refratária.Foram realizados estudos ecocardiográficos e hemodinâmicos (cateter micro-tip) simultâneos, antes (basal) e após (20,40 e 60min) à administraçäo de um comprimido de 200mg de IBO.Para cada fase obtidas as relaçöes pressäo/diâmetro e esforço/de formaçäo do ventrículo esquerdo (VE).A partir destas relaçöes foram analisadosfrequência cardíaca (FC-bpm), débito cardíaco (DC-L/m), pressäo diastólica final (PDF-mmHg); fraçäo de encurtamento (D por cento); elastância máxima (E máx - mmHg/cm/s);esforços sistólico final (ESF-g/cm2) e diastólito final (EDF-g/cm2); rididez da cavidade (Kp-mmHg/cm) e do músculo cardíaco (Km-g/cm2);e tempo da constante de relaxamento (Tau-ms).RESULTADOS- Na condiçäo basal e aos 20,40 e 60min após a administraçäo da IBO, näo houve variaçäo significante na FC (99+-7;99+-8e99+-10), e foram observados aumentos signifacantes do DC (4,13+-1,28;4,95+-1,38;5,13+-1,86;5,18+-1,57), do D por cento (13,7+-2,4;15,4+-2,8;15,9+-1,8;16,1+-2,0), e da E máx (14,8+-3,2;16+-3,6;17,7+-4,2;17,6+-4,2).Houve mudanças significativas, com aumento transitório inicial seguido de diminuiçäo da PDF ( 26,3+-4,2;30,6+-6,4;24,6+-5,6;22,3+-4,6) do EDF (79,7+-22,8;91,7+-29,6;79+-31;63+-17,3) e do Kp (27,2+-12,6;60+-26,7;27,9+-11,7;28+-11).CONCLUSAO - A IBO produziu efeito benéfico na funçäo sistólica e diastólica do VE, bem como aumentou a contratilidade em pacientes com insuficiência cardíaca severa devido à cardiomiopatia dilatada idiopática

ABSTRACT

Purpose - The effects of ibopamine (IBO) on left ventricular (LV) mechanics and contractility have not been described. The aim of this study was to test the hypothesis that IBO has a contractile effect at a dose of 200mg. Methods - Ten male patients (43±7 years) with refractory heart failure due to idiopathic dilated cardiomyopathy were studied. The patients were submitted to simultaneous echo-Doppler and hemodynamic (microtip catheter) studies, before (B) and after (20, 40 and 60 minutes) a dose of 200mg of IBO. LV pressure/diameter and stress/strain relations were obtained. Subsequently, heart rate (HR-bpm), cardiac output (CO-L/m), end-diastolic pressure (EDPmmHg); fractional shortening (FS-%); maximal elastance (Emax-mmHg/cm/s); end systolic (ESS-g/cm2) and enddiastolic (EDS-g/cm2) stress; chamber (Kp-mmHg/cm) andmuscle (Km-g/cm2) stiffness, and the time of constant relaxation (Tau-ms) were analyzed. Results - Results were presented as mean ± standard deviation for conditions before and after IBO (20, 40 and 60 minutes) respectively. There was no change in HR (99±7; 100±7; 99±8; 99±10). Significant increa ses were observed in CO (4.13±1.28; 4.95±1.38; 5.13±1.86;5.18±1.57), FS (13.7±2.4; 15.4±2.8; 15.9±1.8; 16.1±2.0), and Emax (14.8±3.2; 16±3.6; 17.7±4.2; 17.6±4.2). A transient (20 minutes) increase followed by a decrease (40 and 60 minutes) ocurred in EDP (26.3±4.2; 30.6±6.4; 24.6±5.6; 22.3±4.6), EDS (79.7±22.8; 91.7±29.6; 79±31; 63±17.3), and Kp (27.2±12.6; 60±26.7; 27.9±11.7; 28.1±11). Conclusion - IBO has a beneficial effect on LV systolic and diastolic function as well as on contractility in patients with heart failure due to idiopathic dilated cardiomyopathy