Cardiac function and dysfunction in hypertension

Effects of Different Systolic Blood Pressure Targets on Myocardial Function: A One-Year Follow-Up in Geriatric Hypertension

Background

A lower systolic blood pressure (SBP) target reduces major cardiovascular events and mortality from any cause of geriatric hypertension. However, the effect of different SBP targets on myocardial function remains unclear. This study aimed to determine changes in left ventricular (LV) strain in older hypertensive patients after 1 year of different SBP goals, and to evaluate its effects on myocardial mechanics in this population.

Methods

We studied 313 hypertensive adults aged 60 years or older after 1 year of the Systolic Blood Pressure Intervention Trial. They were divided into the intensive group (target SBP: 110–130 mmHg) and the standard group (target SBP: 130–150 mmHg). All participants underwent echocardiography within 1 week after enrollment and 1 year after participating in the study. Global longitudinal strain (GLS) of the LV (endocardial, middle, and epicardial layer: GLS-end, GLS-mid, and GLS-epi, respectively) and the improvement of GLS at 1 year (ΔGLS-end, ΔGLS-mid, and ΔGLS-epi) were measured.

Results

At 1 year, GLS-end in the intensive group was slightly improved compared with that before the trial (−23.78%±3.10% vs −22.58%±3.11%, P<0.05). The ΔGLS-end and ΔGLS-mid in the intensive group were higher than those in the standard group (1.20±0.23 vs 0.58±0.59% and 0.70±0.21 vs 0.52±0.17, P<0.05). Moreover, SBP at 1 year and an angiotensin II type 1 receptor antagonist were independent factors that affected ΔGLS-end (β= −0.005, P=0.004; β= 0.080, P<0.001, respectively).

Conclusion

These trial results suggest that a lower SBP target can slightly improve myocardial function in older hypertensive patients at 1 year.

Impaired cardiac and sympathetic autonomic control in rats differing in acetylcholine receptor sensitivity

Acetylcholine receptors (AChR) are important in premotor and efferent control of autonomic function; however, the extent to which cardiovascular function is affected by genetic variations in AChR sensitivity is unknown. We assessed heart rate variability (HRV) and baroreflex sensitivity (BRS) in rats bred for resistance (FRL) or sensitivity (FSL) to cholinergic agents compared with Sprague-Dawley rats (SD), confirmed by using hypothermic responses evoked by the muscarinic agonist oxotremorine (0.2 mg/kg ip) ( n ≥ 9 rats/group). Arterial pressure, ECG, and splanchnic sympathetic (SNA) and phrenic (PNA) nerve activities were acquired under anesthesia (urethane 1.3 g/kg ip). HRV was assessed in time and frequency domains from short-term R-R interval data, and spontaneous heart rate BRS was obtained by using a sequence method at rest and after administration of atropine methylnitrate (mATR, 2 mg/kg iv). Heart rate and SNA baroreflex gains were assessed by using conventional pharmacological methods. FRL and FSL were normotensive but displayed elevated heart rates, reduced HRV and HF power, and spontaneous BRS compared with SD. mATR had no effect on these parameters in FRL or FSL, indicating reduced cardiovagal tone. FSL exhibited reduced PNA frequency, longer baroreflex latency, and reduced baroreflex gain of heart rate and SNA compared with FRL and SD, indicating in FSL dual impairment of cardiac and circulatory baroreflexes. These findings show that AChR resistance results in reduced cardiac muscarinic receptor function leading to cardiovagal insufficiency. In contrast, AChR sensitivity results in autonomic and respiratory abnormalities arising from alterations in central muscarinic and or other neurotransmitter receptors.

Left ventricular diastolic dysfunction in patients with hypertension and preserved systolic function

OBJECTIVE

To assess prospectively diastolic function in hypertensive patients with preserved left ventricular function, particularly focusing on the limitation of the transmitral flow velocity curve alone to detect diastolic dysfunction.

PATIENTS AND METHODS

Comprehensive Doppler analysis was performed in 51 hypertensive patients with preserved left ventricular systolic function.

RESULTS

The ratio of the peak early diastolic filling wave velocity to the peak velocity of filling wave at atrial contraction was less than the age-adjusted mean value minus 2 SD in 16 patients, and the other 35 patients had a "normal" transmitral Doppler signal. However, the combined transmitral and pulmonary venous Doppler analysis revealed that 12 of these 35 patients had a "pseudonormal" pattern. The prevalence of diastolic dysfunction was estimated at 31% with use of transmitral Doppler alone but increased to 55% when comprehensive Doppler analysis was used (P < .05).

CONCLUSION

The presence of diastolic dysfunction has been frequently overlooked in hypertensive patients with transmitral Doppler analysis alone, and an assessment of diastolic function with a comprehensive Doppler analysis is needed in patients at risk for diastolic dysfunction.