Left ventricular systolic response to exercise in patients with systemic hypertension without left ventricular hypertrophy

Left atrial strain predicts cardiovascular response to exercise in young adults with suboptimal blood pressure

AIMS

To investigate the left ventricular response to exercise in young adults with hypertension, and identify whether this response can be predicted from changes in left atrial function at rest.

METHODS

A total of 127 adults aged 18-40 years who completed clinical blood pressure assessment and echocardiography phenotyping at rest and during cardiopulmonary exercise testing, were included. Measurements were compared between participants with suboptimal blood pressure ≥120/80mm Hg (n = 68) and optimal blood pressure <120/80mm Hg (n = 59). Left ventricular systolic function during exercise was obtained from an apical four chamber view, while resting left atrial function was assessed from apical four and two chamber views.

RESULTS

Participants with suboptimal blood pressure had higher left ventricular mass (p = 0.031) and reduced mitral E velocity (p = 0.02) at rest but no other cardiac differences. During exercise, their rise in left ventricular ejection fraction was reduced (p = 0.001) and they had higher left ventricular end diastolic and systolic volumes (p = 0.001 and p = 0.001, respectively). Resting cardiac size predicted left ventricular volumes during exercise but only left atrial booster pump function predicted the left ventricular ejection fraction response ( β = .29, p = 0.011). This association persisted after adjustment for age, sex, body mass index, and mean arterial pressure.

CONCLUSION

Young adults with suboptimal blood pressure have a reduced left ventricular systolic response to exercise, which can be predicted by their left atrial booster pump function at rest. Echocardiographic measures of left atrial function may provide an early marker of functionally relevant, subclinical, cardiac remodelling in young adults with hypertension.

[Nuclear cardiology: technical bases and clinical applications]

Although the role of nuclear cardiology is currently well consolidated, the addition of new radiotracers and modern techniques makes it necessary to continuously update the requirements, equipment and clinical applications of these isotopic tests. The characteristics of the radioisotopic drugs and examinations presently used are explained in the first part of this text. In the second, the indications of them in diagnostic and prognostic evaluation of the different coronary diseases are presented.

Divergent cardiac response to exercise in essential hypertension vs. normotension and the effect of enalapril

The aims of this study were to examine (1) the cardiac response to exercise in essential hypertension and (2) the effect of long-term enalapril treatment on cardiac reserve. Ten normotensive control subjects and 15 patients with moderate, essential hypertension underwent radionuclide ventriculography during graded, supine exercise (0 W-50 W-100 W). The hypertensive patients were studied during monotherapy using hydrochlorothiazide and 3 and 12 months after supplementation with enalapril 10-40 mg o.d. During exercise, the control subjects demonstrated a 17% increase in left ventricular ejection fraction (LVEF) mediated by a 30% decrease in end-systolic volume, a small increase in stroke volume and a minor biphasic (increase-decrease) change in end-diastolic volume. In the hypertensive patients, both the end-diastolic and the end-systolic volume increased substantially with no increase in LVEF, although stroke volume increased by 33%. Long-term therapy with enalapril induced only a minor change towards a more normal pattern of cardiac response to exercise. The hypertensive patients increased their stroke volume during exercise by recruiting preload reserve instead of increasing contractility. Long-term treatment with enalapril had little, if any, effect on this abnormal cardiac response.

Maximal exercise hemodynamics and risk of mortality in apparently healthy men and women

The purpose of this investigation was to determine the association of maximal exercise hemodynamic responses with risk of mortality due to all-causes, cardiovascular disease (CVD), and coronary heart disease (CHD) in a population of apparently healthy individuals. Study participants were 20,387 men (mean age = 42.2 yr) and 6,234 women (mean age = 41.9 yr), patients of a preventive medicine center in Dallas, TX, examined between 1971 and 1989. Maximal heart rate and maximal systolic blood pressure (SBP) measured during the maximal exercise test were related to risk of all-cause, CVD, and CHD mortality. During an average of 8.1 yr of follow-up, there were 348 deaths in men and 66 deaths in women. Among men, after adjustment for confounding variables, risks (and 95 percent confidence interval (CI)) of all-cause mortality for quartiles of maximal SBP, relative to the lowest quartile, were: 0.96 (0.70-1.33), 1.36 (1.01-1.85), and 1.37 (0.98-1.92) for quartiles 2-4, respectively. Similarly adjusted risks for maximal heart rate were: 0.61(0.44-0.85), 0.69 (0.51-0.93), and 0.60 (0.41-0.87). Similar results were seen for risk of CVD and CHD death. In women, similar trends in adjusted risks of all-cause and CVD mortality across maximal SBP and heart rate categories were observed. For maximal heart rate, a 35 bpm higher value was associated with a 36 percent decreased risk of CVD mortality in men (RR = 0.63,95 percent CI = 0.34-0.71) and an 8 percent lower risk in women (RR = 0.92,95 percent CI = 0.18-4.63). These results suggest that an exaggerated SBP or an attenuated heart rate response to maximal exercise may indicate an elevated risk for mortality in this apparently healthy population.

Left ventricular ejection fraction during supine and upright exercise in patients with systemic hypertension and its relation to peak filling rate

In hypertensive patients with hypertrophy, abnormal peak filling rate (PFR) is related to a decline in left ventricular (LV) ejection fraction (EF) during supine exercise. Because an increased LV preload is more common during upright exercise, we determined this relation during upright and supine exercise. In 20 hypertensive patients, rest and exercise radionuclide angiography in the supine and upright positions, as well as echocardiography, were performed and compared with 20 age-matched controls. At rest in the supine and upright positions, blood pressure, LVEF, and PFR were 164 +/- 20/94 +/- 10 and 164 +/- 24/94 +/- 10 mm Hg, 65 +/- 8% and 65 +/- 6%, and 2.77 +/- 0.59 and 2.70 +/- 0.52 end-diastolic volumes/s, respectively. PFR was reduced compared with controls (3.29 +/- 0.3 and 3.27 +/- 0.27 end-diastolic volumes/s, supine and upright). LV mass index was normal (94 +/- 19 g/m2). LVEF increased during upright but not during supine exercise in the hypertensives. Four patients had a decline in each position versus none of the controls. There was no relation between the change in LVEF and rest PFR. In patients with mild to moderate hypertension without extensive hypertrophy, abnormal filling rates were present but did not correlate with the change in LVEF with exercise.

Precursors of established hypertension in borderline hypertensives. A two-year follow-up

We performed exercise testing, 24-h ambulatory blood pressure monitoring and echocardiography in 37 selected patients with borderline hypertension (24 men and 13 women, mean age 39.8 years, range 23-50) in an attempt to detect early cardiovascular changes that could predict future established hypertension. All subjects were clinically reinvestigated after a mean period of 28 +/- 4 months. At entry 24/37 (65%) showed an exaggerated blood pressure response to exercise (systolic pressure > or = 220 mmHg and/or diastolic pressure > or = 105 mmHg) while 13 (35%) had a normal pressure response. Patients with exaggerated pressure response showed significantly higher left ventricular mass index in comparison to those with normal pressure response (98.1 +/- 10.7 vs. 84 +/- 13, respectively; P < 0.05). They also had higher, although not significantly different, average 24-h systolic and diastolic blood pressure levels. At follow up seven subjects (16%) were diagnosed as having established hypertension, while 30 (84%) remained borderline hypertensives. No subject was judged normotensive. All of the seven hypertensive subjects were a proportion (7/24 = 29%) of the group with exaggerated blood pressure response to exercise. Also, they were the eldest of the total group of borderlines (mean age 44 years) and had the highest left ventricular mass index (100.6 +/- 13 g/m2). Borderline hypertensives show a spectrum of cardiovascular changes that could be considered as a part of the hypertensive risk profile. However, there are no specific characteristics that reliably distinguish subjects prone to develop hypertension. Repeated clinical observations and correct measurements of resting blood pressure may have greater relevance in the management of patients with borderline hypertension.

Effect of beta-blockade on low heart rate-related ischemia during mental stress

To explore the effect of beta-adrenergic blockade on low heart rate-related (mental stress) ischemia, 19 patients with coronary artery disease were randomized into a double-blind crossover trial of metoprolol, 100 mg twice daily, and underwent serial mental stress/bicycle exercise studies. Mental stress-induced wall motion abnormalities occurred at a lower heart rate than exercise-induced wall motion abnormalities during placebo administration (81 +/- 16 vs. 123 +/- 20 beats/min, p less than 0.05). Metoprolol reduced the mean magnitude of exercise-induced wall motion abnormalities (2.8 +/- 2.0 vs. 1.6 +/- 2.4, p = 0.003); improvement was related to the magnitude of hemodynamic beta-blockade effect. Metoprolol did not significantly reduce the mean magnitude of mental stress-induced wall motion abnormalities (3.0 +/- 2.2 vs. 2.6 +/- 2.2), although individual responses predominantly either improved (50%) or worsened (29%). Unlike exercise, the magnitude of hemodynamic beta-blockade did not predict mental stress response and metoprolol did not block mental stress-induced blood pressure elevations. Patients with abolition of exercise-induced ischemia were more likely to have reduction of mental stress-induced ischemia. Patients whose ischemia worsened with metoprolol during mental stress had more easily inducible ischemia, as assessed by exercise-induced placebo wall motion abnormality, chest pain and prior myocardial infarction. Beta-blockade was associated with a lowering of ischemia-related hemodynamic thresholds compared with placebo. These results suggest that beta-blockade has a variable effect on low heart rate-related ischemia that may be due to a lack of effect on mental stress-induced blood pressure elevation in patients with easily induced ischemia or to effects on coronary vasomotor tone, or both.

Comparison of ambulatory left ventricular ejection fraction and blood pressure in systemic hypertension in patients with and without increased left ventricular mass

To evaluate the effects of long-standing systemic hypertension on left ventricular (LV) function during daily activities, ambulatory radionuclide monitoring of LV ejection fraction (EF) and blood pressure was performed during exercise and other structured activities in 31 hypertensive patients. Patients were divided into 3 groups based on the absence of LV hypertrophy (group 1 [n = 16], LV mass 107 +/- 12 g/m2), presence of LV hypertrophy without electrocardiographic changes (group 2 [n = 10], LV mass 141 +/- 8 g/m2) and LV hypertrophy with associated electrocardiographic changes (group 3 [n = 5], LV mass 158 +/- 9 g/m2). The groups were similar with respect to age, baseline medication, treated and untreated blood pressure, resting EF and treadmill exercise time. Patients in group 3 had the longest history of hypertension. Peak filling rate was normal in group 1 (2.9 +/- 0.4 end-diastolic volume/s), but reduced at rest in groups 2 (2.4 +/- 0.4) and 3 (2.1 +/- 0.3). Patients in group 1 had normal EF responses to exercise and mental stress testing, as well as during routine ambulatory activities. Patients in group 2 had a blunted EF response to exercise, and those in group 3 had a significantly abnormal response. Both group 2 and 3 patients demonstrated abnormal EF responses to mental stress, as well as cold pressor testing in association with significant increases in mean arterial pressure and marked reduction in diastolic filling rate. Decreases in EF were also observed during routine patient monitoring in 3 group 3 patients and 4 group 2 patients. These events were associated with significantly increased blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)