Stress induced hypertensive response: should it be evaluated more carefully?

Blood pressure response during exercise testing in individuals with and without hypertension: The value of the recovery phase

BACKGROUND

Hypertension and exercise testing are essential for cardiovascular risk assessment. However, an exact description of blood pressure (BP) in patients with a hypertensive response during exercise (HRE), especially in the recovery phase is lacking. Herein, we aimed to analyse BP and heart rate during exercise testing and recovery in patients with an HRE.

METHODS

800 patients aged 17-90 with an HRE during a standardized bicycle ergometry test were recruited. The BP behaviour during exercise testing was correlated with clinical data. Furthermore, data were analysed according to the presence of pre-existent hypertension.

RESULTS

Of the 800 patients included in this study 497 (62%) were previously diagnosed with hypertension. Analysis of covariance showed a significantly faster systolic (β [95% CI] 8.0 [4.9-11.1]) and diastolic (2.4 [0.4-4.4]) BP recovery 3 min after maximal exercise in patients without hypertension in univariable models. These results remained robust in fully adjusted models taking into account age, sex, body mass index, cardiovascular disease, and antihypertensive treatment for systolic (5.3 [1.2-9.4]) and diastolic BP (4.5 [1.9-7.0]). Furthermore, patients with hypertension displayed higher systolic BP during maximal exercise in univariable (3.8 [0.1-7.5]) and fully adjusted (5.5 [1.1-10.0]) models. There was no difference in maximum diastolic BP between groups.

CONCLUSION

In this large cohort study, patients without hypertension showed a faster systolic and diastolic BP recovery and lower maximal systolic BP compared to patients with hypertension. Overall, this study provides new insights into cardiovascular health during recovery phase.

Prevalence and prognostic implications of hypertensive response to exercise in patients with hypertrophic cardiomyopathy

Objective

Hypertensive response to exercise (HRE) is observed in patients with hypertrophic cardiomyopathy (HCM) with normal resting blood pressure (BP). However, the prevalence or prognostic implications of HRE in HCM remain unclear.

Methods

In this study, normotensive HCM subjects were enrolled. HRE was defined as systolic BP > 210 mmHg in men or >190 mmHg in women, or diastolic BP > 90 mmHg, or an increase in diastolic BP > 10 mmHg during treadmill exercise. All participants were followed for subsequent development of hypertension, atrial fibrillation (AF), heart failure (HF), sustained ventricular tachycardia/fibrillation (VT/VF), and all-cause death. Six hundred and eighty HCM patients were screened.

Results

347 patients had baseline hypertension, and 333 patients were baseline normotensive. 132 (40%) of the 333 patients had HRE. HRE was associated with female sex, lower body mass index and milder left ventricular outflow tract obstruction. Exercise duration and metabolic equivalents were similar between patients with or without HRE, but the HRE group had higher peak heart rate (HR), better chronotropic response and more rapid HR recovery. Conversely, non-HRE patients were more likely to exhibit chronotropic incompetence and hypotensive response to exercise. After a mean follow-up of 3.4 years, patients with and without HRE had similar risks of progression to hypertension, AF, HF, sustained VT/VF or death.

Conclusion

HRE is common in normotensive HCM patients during exercise. HRE did not carry higher risks of future hypertension or cardiovascular adverse outcomes. Conversely, the absence of HRE was associated with chronotropic incompetence and hypotensive response to exercise.

Ultimate phases of hypertensive heart disease and stressed heart morphology by conventional and novel cardiac imaging

Early recognition of hypertensive heart disease is needed to prevent macrovascular and microvascular damage. Hypertension (HTN) is a risk factor for coronary artery disease, and plays a prominent role in the development of adverse left ventricular (LV) remodeling and heart failure. Here, we review new knowledge on effects of HTN on cardiac geometry and function, obtained from multimodality cardiac imaging, including echocardiography, positron emission tomography and magnetic resonance imaging. Early recognition of changes in LV geometry and function induced by HTN could identify patients at risk for end-organ damage, who could be targeted for close monitoring and intensive therapy. Basal septal hypertrophy as the early imaging biomarker at the adaptive phase may be a specific aspect not only in hypertensive heart but stress-related conditions and called stressed heart morphology.

Could early septal involvement in the remodeling process be related to the advance hypertensive heart disease?

BACKGROUND

Quantitative imaging analyses showed an earlier septal wall involvement in hypertension. We planned to determine the effect of hypertension on regional myocardial performance index (MPI) in a hypertensive patient population.

METHODS

We evaluated 119 hypertensive patients who were divided into gr. I: 57 patients without left ventricular hypertrophy (LVH), (53.1 ± 10 years), and gr. II: 62 patients with LVH (55.1 ± 9 years) using conventional and tissue doppler imaging. They were compared with gr. III, a sex-age-matched normal control group (37 subjects, 53.0 ± 10 years).

RESULTS

We detected basal septal and basal lateral contraction time (CT), isovolumetric CT and relaxation time (IVRT) and MPI. EF was 68 ± 5 % in gr. I, 69 ± 5 % in gr. II, 69 ± 4 % in gr. III. LV mass index was 122 ± 11 g/m2 in gr. I, 148 ± 13 g/m2 in gr. II and 118 ± 13 g/m2 in gr. III. Concentric LVH was detected in gr. II (relative wall thickness = 0.49 ± 0.8). LV septal and lateral MPI were abnormal in both hypertensive groups (p < 0.0001). Septal MPI was correlated moderately with septal wall thickness (r = 0.447, p < 0.001).

CONCLUSIONS

LV diastolic dysfunction becomes more severe in septal wall than lateral wall in hypertensive LVH. Septal myocardial performance is more dominantly affected by hypertension possibly due to earlier septal involvement in disease course. Septal MPI is correlated moderately with septal wall thickness.

Loss of functional endothelial connexin40 results in exercise-induced hypertension in mice

During activity, coordinated vasodilation of microcirculatory networks with upstream supply vessels increases blood flow to skeletal and cardiac muscles and reduces peripheral resistance. Endothelial dysfunction in humans attenuates activity-dependent vasodilation, resulting in exercise-induced hypertension in otherwise normotensive individuals. Underpinning activity-dependent hyperemia is an ascending vasodilation in which the endothelial gap junction protein, connexin (Cx)40, plays an essential role. Because exercise-induced hypertension is proposed as a forerunner to clinical hypertension, we hypothesized that endothelial disruption of Cx40 function in mice may create an animal model of this condition. To this end, we created mice in which a mutant Cx40T152A was expressed alongside wildtype Cx40 selectively in the endothelium. Expression of the Cx40T152A transgene in Xenopus oocytes and mouse coronary endothelial cells in vitro impaired both electric and chemical conductance and acted as a dominant-negative against wildtype Cx40, Cx43, and Cx45, but not Cx37. Endothelial expression of Cx40T152A in Cx40T152ATg mice attenuated ascending vasodilation, without effect on radial coupling through myoendothelial gap junctions. Using radiotelemetry, Cx40T152ATg mice showed an activity-dependent increase in blood pressure, which was significantly greater than in wildtype mice, but significantly less than in chronically hypertensive, Cx40knockout mice. The increase in heart rate with activity was also greater than in wildtype or Cx40knockout mice. We conclude that the endothelial Cx40T152A mutation attenuates activity-dependent vasodilation, producing a model of exercise-induced hypertension. These data highlight the importance of endothelial coupling through Cx40 in regulating blood pressure during activity.

Investigation on cardiovascular risk prediction using physiological parameters

Cardiovascular disease (CVD) is the leading cause of death worldwide. Early prediction of CVD is urgently important for timely prevention and treatment. Incorporation or modification of new risk factors that have an additional independent prognostic value of existing prediction models is widely used for improving the performance of the prediction models. This paper is to investigate the physiological parameters that are used as risk factors for the prediction of cardiovascular events, as well as summarizing the current status on the medical devices for physiological tests and discuss the potential implications for promoting CVD prevention and treatment in the future. The results show that measures extracted from blood pressure, electrocardiogram, arterial stiffness, ankle-brachial blood pressure index (ABI), and blood glucose carry valuable information for the prediction of both long-term and near-term cardiovascular risk. However, the predictive values should be further validated by more comprehensive measures. Meanwhile, advancing unobtrusive technologies and wireless communication technologies allow on-site detection of the physiological information remotely in an out-of-hospital setting in real-time. In addition with computer modeling technologies and information fusion. It may allow for personalized, quantitative, and real-time assessment of sudden CVD events.

Orexin A regulates cardiovascular responses in stress-induced hypertensive rats

Several pieces of evidence indicate that the rostral ventrolateral medulla (RVLM) is probably one of the key neural structures mediating the pressor effects of orexins in the brain. Nitric oxide synthase/nitric oxide (NOS/NO) system in the RVLM modulates cardiovascular activities. Our experiments were designed to test the hypothesis that orexin-A (OXA) is involved in the mechanism of stress-induced hypertension (SIH) by adjusting NOS/NO system in the RVLM. The stress-induced hypertensive rats (SIHR) model was established by electric foot-shocks and noises. Here we examined the expression of OXA immunoreactive (OXA-IR) cells in the lateral hypothalamus (LH) and the protein level of orexin 1 receptor (OX1R) in the RVLM of SIHR, and we found that the expressions of OXA-IR and OX1R were higher than those of the control group. The double-staining immunohistochemical evidence showed that OX1R immunoreactive (OX1R-IR) cells and neuronal nitric oxide synthase (nNOS) or inducible nitric oxide synthase (iNOS) immunoreactive (IR) cells were co-localizated in the RVLM. Microinjection of OXA (10, 50, 100 pmol/100 nl) into the unilateral (right) RVLM of control rats or SIHR produced pressor and tachycardiac effects in a dose-dependent manner. SB-408124 (100 pmol/100 nl, an antagonist of OX1R) or TCS OX2 29 (100 pmol/100 nl, an antagonist of OX2R) partly abolished the cardiovascular effects of exogenously-administrated OXA into the RVLM of control rats and SIHR, and lowered the increased systolic blood pressure (SBP) and heart rate (HR) of SIHR, with no difference in statistical significance between the two antagonists' effects. Microinjection into the RVLM of both control and SIHR groups of 7-Ni (0.05 pmol/100 nl, nNOS inhibitor) or Methylene Blue [100 pmol/100 nl, an inhibitor of soluble guanylate cyclase (sGC)] suppressed the OXA-induced increase of SBP and HR, whereas microinjection of AG (1, 10, 100 pmol/100 nl) had no obvious effects on the OXA-induced increase of SBP and HR. Our results indicate that OXA in the RVLM may participate in the central regulation of cardiovascular activities in SIHR, and OX1R and OX2R both have important roles in it. The cardiovascular effects of OXA in the RVLM may be induced by nNOS-derived NO, which activated sGC-associated signaling pathway.