Does the Intraventricular Pressure Gradient Increase following Acute High Intensity Interval Exercise in Heart Failure?

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An increase in the diastolic intraventricular pressure gradient (IVPG) is an important mechanism that aids in left ventricular filling during exercise. Prior work has shown that individuals with severe heart failure have impairment in IVPG at peak exercise (Am J Physiol Heart Circ Physiol 2005; 289: H2081-H2088). We have previously shown in the present study cohort (J Appl Physiol 2011; 110: 398-406) that left ventricular peak twist reserve is blunted, but that left ventricular peak untwisting rate, due to an increase in peak basal rotation rate and not peak apical rotation rate, is enhanced following acute high intensity interval (HIT) exercise in patients with mild heart failure. It is unclear whether regional differences in rotational properties of the ventricle in heart failure (i.e., base versus apex) that we have observed affect the IVPG post-HIT. PURPOSE: To determine if the IVPG immediately following acute HIT would be increased despite impaired apical contribution to left ventricular untwisting. METHODS: Nine patients (49 ± 16 years; 6 male) with mild heart failure (NYHA Class I/II = 7/2; left ventricular ejection fraction = 36 ± 7%; peak VO2 = 27 ± 9 ml/kg/min) performed 1 session of HIT (4 × 4 min at 96 ± 10% peak heart rate with a 3 min recovery period between bouts). Cardiac MRI (1.5 T scanner) was performed at rest prior to HIT and 6 ± 2 min following HIT. Rotational mechanics and IVPG were analyzed using in-house techniques with custom software. Analyses were performed using 2-tailed paired t-testing with p<0.05 being significant. RESULTS: Our novel finding is that the IVPG from pre-HIT (1.8 ± 1.0 mmHg) to post-HIT (1.6 ± 0.7 mmHg) remained effectively unchanged (p>0.05), despite a significant 24% increase in untwisting rate (p<0.05) that was modulated primarily by an increase in peak basal and not peak apical rotation rate. CONCLUSION: The maintenance of, but not the increase in, IVPG may aid in diastolic filling following HIT in patients with mild heart failure. Impairment in apical rotational mechanics likely account for the poor IVPG reserve of the left ventricle in mild heart failure.