Regional hippocampal damage in heart failure

Abstract

Aims: Heart failure (HF) patients show cognitive and mood impairments, including short-term memory loss and depression, that have an adverse impacting on quality of life and self-care management. Brain regions, including the hippocampus, a structure significantly involved in memory and mood, show injury in HF, but the integrity of specific hippocampal subregions is unclear.

Methods and results: To assess regional hippocampal volume loss, we evaluated 17 HF patients (mean age ± SD, 54.4 ± 2.0 years; 12 male, left ventricular ejection fraction 28.3 ± 6.8%; New York Heart Association class II/III 94%/6%) and 34 healthy control subjects (52.3 ± 1.3 years; 24 male) using high-resolution T1-weighted magnetic resonance imaging and evaluated localized surface changes with morphometric procedures. Hippocampi were manually outlined, and volumes calculated from normalized tracings. Volume differences between groups were assessed by two-sample t-tests, and regional differences were assessed by surface morphometry. Patients with HF exhibited smaller hippocampal volumes than controls (right 3060 ± 146 mm(3) vs. 3478 ± 94 mm(3), P = 0.02; left 3021 ± 145 mm(3) vs. 3352 ± 98 mm(3), P = 0.06). Volume reductions were detected principally in CA1, an area integral to an array of learning and memory functions, as well as in mid to posterior CA3 and subiculum.

Conclusion: The hippocampus shows regional volume reduction in HF, which may contribute to short-term memory loss and depression associated with the condition.

Keywords: Brain; Cognition; Hippocampus; Magnetic resonance imaging; Memory.

Figure 1

Scatter plot demonstrates individual left and right hippocampal volumes in control (x) and HF (o) subjects. The right hippocampal volumes differed significantly between groups.

Figure 2

Significance maps of the right and left hippocampus demonstrate localized regions of significant change in HF subjects relative to control subjects. The white regions correspond to those areas with the most significant change (p < 0.01). Significant declines appeared in the anterior medial hippocampus (Fig.2a), as well as in the subiculum and CA3, with possible minor involvement of the dentate gyrus (Fig.2b). The most pronounced declines appeared along the lateral aspect of the hippocampus, which contains the CA1 region (Fig. 2c–e, h). A small region of anterior subiculum/presubiculum also exhibited significant differences (Fig.2f, g).

Figure 3

Ratio maps display color-coded ratios of mean radial distance, in patients relative to controls, and demonstrate specific areas of atrophy and the relative magnitude of HF atrophy in each area. The right side exhibits more extensive atrophy than the left hippocampus. Areas of red and orange represent the most severe local volume loss, and are spatially distributed in a pattern similar to that of the significance maps of Figure 2.