Cardiovascular effects of non-depolarizing neuromuscular blockers in patients with aortic valve disease

To compare haemodynamic responses associated with equipotent doses of neuromuscular blockers and high-dose fentanyl (50 micrograms.kg-1), 40 patients with aortic valve stenosis (AS) and 20 patients with aortic insufficiency (AI) were randomized to four study groups to receive the following: (1) pancuronium 0.12 mg.kg-1, (2) vecuronium 0.12 mg.kg-1, (3) atracurium 0.4 mg.kg-1, or (4) pancuronium-metocurine mixture (0.4 mg + 1.6 mg/ml): 1 ml/10 kg). Neuromuscular blockers were injected at the same time with the fentanyl; haemodynamics were recorded with the patients awake (baseline), at two minutes post-induction, and at two and five minutes after intubation. In patients with AS, pancuronium increased heart rate more than vecuronium or atracurium; heart rates were also higher with the pancuronium-metocurine mixture than with vecuronium. Although there were no ECG signs of ischaemia, one patient given pancuronium developed severe hypotension associated with tachycardia. Reductions in SVR after atracurium allowed small but significant (p less than 0.01) decreases in MAP which were well tolerated; one patient, however, did develop severe hypotension. Intubation resulted in significant (p less than 0.01) increases in MAP in the pancuronium-metocurine mixture group. Vecuronium permitted the most stable overall haemodynamic course at all measurement times. In contrast, patients with AI showed stable haemodynamics after vecuronium, pancuronium and the pancuronium-metocurine mixture; one patient became tachycardic following vecuronium. Atracurium caused unexplained elevations in diastolic and mean arterial pressures which were significant when compared to vecuronium (p less than 0.01). These results in increases in PCWP; mean PA pressures and CVP were also increased. These effects of atracurium inpatients with Al need further evaluation.