Objective: The purpose of this study was to investigate whether isoflurane, a known negative lusitropic agent, exacerbates diastolic dysfunction in patients with preexisting impaired relaxation.
Design: Prospective, experimental study.
Setting: Single-institution, university hospital.
Participants: Twenty-five patients with diastolic dysfunction due to concentric hypertrophy and ischemic heart disease undergoing elective coronary artery bypass graft surgery.
Interventions: After approval of the local ethics committee and informed consent, patients randomly received sufentanil/midazolam anesthesia plus either 0.5 to 1.0 minimum alveolar concentration of isoflurane (n = 15) or weight-adjusted boli of urapidil (n = 10) during preparation of the internal mammary artery. Changes in hemodynamic parameters and echocardiographic diastolic indices before and after drug administration were compared. Filling pressures during the study were kept constant within normal range.
Measurements and main results: Hemodynamic changes measured by invasive arterial and pulmonary arterial pressures were comparable between isoflurane and urapidil. Both interventions led to a marked reduction in afterload that was accompanied by a significant increase in thermodilution cardiac output and stroke volume. Transesophageal echocardiographic relaxation indices were also comparable between groups. Transmitral and tissue Doppler E waves increased significantly, leading to larger E/A and Em/Am ratios; whereas the deceleration time and the isovolumetric relaxation time decreased significantly.
Conclusion: Isoflurane did not exacerbate diastolic dysfunction in patients with concentric hypertrophy and ischemic heart disease. In contrast, isoflurane led to a "normalization" of the relaxation pattern that was attributed to a reduction in left-ventricular loading conditions.