Haemodynamic and catecholamine response to simulated ventricular tachycardia in man: effect of baseline left ventricular function

Abstract

Objective: To examine the effects of baseline left ventricular function on the haemodynamic and catecholamine responses to ventricular tachycardia.

Design: Experimental cohort study.

Setting: Cardiac catheterisation laboratory in tertiary referral centre.

Subjects: 24 patients (19 male, 5 female; mean (SD) age, 59 (10) years) without coronary artery disease, divided into two groups with normal or impaired left ventricular function: group A, ejection fraction > 65% (n = 10); group B, ejection fraction < 45% (n = 14). Other medical and demographic factors were similar in the two groups.

Interventions: Ventricular tachycardia was simulated with rapid pacing at 150 beats/min for 10 minutes.

Main outcome measures: Arterial blood pressure; venous plasma catecholamine concentrations.

Results: During rapid pacing, blood pressure was lower in group B (with impaired left ventricular function) than in group A: systolic blood pressure, 102 (11) v 115 (9) mm Hg (p = 0.005); mean blood pressure, 79 (6) v 85 (6) mm Hg (p = 0.02). The ejection fraction correlated with the lowest systolic blood pressure (r = 0.64, p = 0.0006). Although the rise in adrenaline was comparable between the two groups, the rise in noradrenaline was more pronounced (p < 0.05) in patients in group B.

Conclusion: At low rates and in selected patients, the underlying state of left ventricular function affects haemodynamic tolerance of ventricular tachycardia. Patients with impaired left ventricular function have a lower blood pressure during ventricular tachycardia, despite an exaggerated noradrenaline release.

Figure 1

Systolic and mean blood pressure response (at first, fifth, and 10th minute of simulated ventricular tachycardia, and the first, fifth, and 10th minute post-termination), in patients with normal left ventricular function (filled circles) and impaired left ventricular function (empty circles). *Significant difference between the two groups (p < 0.05). LV, left ventricular; p, post.

Figure 2

Correlations between ejection fraction and systolic blood pressure for all study patients. (A) Correlation between ejection fraction and lowest recorded systolic blood pressure during simulated ventricular tachycardia. (B) Correlation between ejection fraction and maximum hypotensive response, expressed as per cent fall in systolic blood pressure compared with baseline. (C) Correlation between ejection fraction and “steady state” systolic blood pressure (see text for explanation). EF, ejection fraction; max, maximum; SBP, systolic blood pressure; sVT, simulated ventricular tachycardia.

Figure 3

Plasma catecholamine concentrations (pg/ml) (at the first, fifth, and 10th minute of simulated ventricular tachycardia, and the first, fifth, and 10th minute post-termination), in patients with normal left ventricular function (filled circles) and impaired left ventricular function (empty circles). *Significant difference between the two groups (p < 0.05). (A) Plasma adrenaline. (B) Plasma noradrenaline. LV, left ventricular; p, post.