Myocardial blood flow assessment with 82rubidium-PET imaging in patients with left bundle branch block

OBJECTIVES: Perfusion abnormalities are frequently seen in Single Photon Emission Computed Tomography (SPECT) when a left bundle branch block is present. A few studies have shown decreased coronary flow reserve in the left anterior descending territory, regardless of the presence of coronary artery disease. OBJECTIVE: We sought to investigate rubidium-82 (82Rb) positron emission tomography imaging in the assessment of myocardial blood flow and coronary flow reserve in patients with left bundle branch block. METHODS: Thirty-eight patients with left bundle branch block (GI), median age 63.5 years, 22 (58%) female, 12 with coronary artery disease (≥70%; GI-A) and 26 with no evidence of significant coronary artery disease (GI-B), underwent rest-dipyridamole stress 82Rb-positron emission tomography with absolute quantitative flow measurements using Cedars-Sinai software (mL/min/g). The relative myocardial perfusion and left ventricular ejection fraction were assessed in 17 segments. These parameters were compared with those obtained from 30 patients with normal 82Rb-positron emission tomography studies and without left bundle branch block (GII). RESULTS: Stress myocardial blood flow and coronary flow reserve were significantly lower in GI than in GII (p<0.05). The comparison of coronary flow reserve between GI-A and GI-B showed that it was different from the global coronary flow reserve (p<0.05) and the stress flow was significantly lower in the anterior than in the septal wall for both groups. Perfusion abnormalities were more prevalent in GI-A (p=0.06) and the left ventricular ejection fraction was not different between GI-A and GI-B, whereas it was lower in GI than in GII (p<0.001). CONCLUSION: The data confirm that patients with left bundle branch block had decreased myocardial blood flow and coronary flow reserve and coronary flow reserve assessed by 82Rb-positron emission tomography imaging may be useful in identifying coronary artery disease in patients with left bundle branch block.

Estudo comparativo das bombas de rolete e centrífuga em pacientes submetidos à cirurgia de revascularização do miocárdio / Comparative study of roller and centrifuge pumps in patients undergoing coronary artery bypass graft surgery

Contexto e objetivos: Estudos sugerem que a utilização da bomba centrífuga na circulação extracorpórea é melhor do ponto de vista fisiológico se comparada a bomba de rolete nos pacientes submetidos a cirurgia cardíaca. O objetivo do trabalho é avaliar os níveis séricos delactato em pacientes submetidos a cirurgia de revascularização do miocárdio utilizando as bombas de rolete e centrífugas durante a circulação extracorpórea (CEC) como um marcador prognóstico. Desenho e local: Trata-se de um estudo observacional retrospectivo, baseado em levantamento de dados de prontuários médico hospitalares, realizado no Hospital Sírio-Libanês. Método: Foi estudada uma coorte histórica de pacientes, dividida em dois grupos: o primeiro grupo, de 61 pacientes, operados no período de março de 2007 a julho de 2008, com bomba rolete, e o segundo grupo, de 74 pacientes, no período de julho de 2008 a fevereiro de 2011, com bomba centrífuga. As amostras sanguíneas dos pacientes foram colhidas em quatro diferentes tempos durante a operação: pré-circulação extracorpórea (T1); hipotermia a 32 °C (T2); hipotermia a 34 °C (T3); pós-circulação extracorpórea (T4). Resultados: Houve diferença significativa na amostra do lactato em T4 (P = 0,049). Conclusão: Na bomba centrífuga, observamos melhora do lactato ao final da circulação extracorpórea em comparação com a bomba rolete.