Assessment of Left Ventricular Performance in Patients with Variable States of Hypertrophy Secondary to Essential Hypertension Using a New Load-Independent Index, E' max /V 100

The left ventricular (LV) contractile performance in left ventricular hypertrophy (LVH) induced by chronic pressure overload was assessed in 87 essential hypertensive (EHT) patients. They were classified by the presence of LVH as measured by the sum of LV end-diastolic posterior wall thickness and interventricular septal thickness on echocardiograrn, and the presence of ST-T changes on electrocardiogram into a H1-subgroup (H1) consisting of patients with neither LVH nor ST-T changes, a H2-subgroup (H2) with LVH but without ST-T changes and a H3-subgroup (H3) with both LVH and ST-T changes. Thirty-two normal subjects were used as a normal control group (N).

The relation between the peak systolic pressure and LV end-systolic volume normalized by volume intercept at 100 mmHg peak systolic pressure, E' max/V 100, was used for expression of the LV inotropic state. The peak systolic pressure was measured with a cuff sphygmomanometer and the LV-end systolic volume was determined by echocardiography. To validate whether E’ max/V 100 was insensitive to loading condition, E' max/V 100 obtained during dynamic responses to acute LV afterload reduction by nifedipine (NIF group) was corn pared with that obtained by isosorbide dinitrate-induced preload reduction (ISDN group). E' max/V100 obtained in the NIF and ISDN groups showed similar values in analogous subgroups, indicating the independence of this index on acute reduction in cardiac load.

In the NIF group, E' max/V 100 in H3, 0.13±0.04 mmHg/ml2, was significantly lower than that in H2, 0.23 ±0.05 (p<0.01), and the value in H2 was significantly lower than that in Hl, 0.36±0.17 (p<0. 01). Similarly, the ISDN group showed that E' max/V 100 in H3, 0.15 ±0.07 mmHg/ml2, was significantly decreased from that in H2, 0.21 ± 0.05 (p<0.05) and the value in H2 was significantly less than that in Hl, 0.40±0.17 (p<0.01). Both the NIF and ISDN groups showed no difference in the value of E' max/V 100 in Hl from N, indicating a normal level of LV contractility. The value of E' max/V 100 obtained in both the NIF and ISDN groups did separate the three EHT subgroups (H1, H2 and H3) with a lower LV contractility from those with a normal contractile state.

These findings indicate that in LVH induced by pressure overload the LV contractile state is depressed and becomes further impaired when ST-T changes accompanied LVH. Clinically it is reasonable to assume that the classification of EHT as in this manner is a simple and accurate way to evaluate LV performance. It is also concluded that E' max/V 100, which is easily determined noninvasively, can be used as a load-independent index of LV contractility.