Arterial distensibility as a possible compensatory mechanism in chronic aortic regurgitation

OBJECTIVE: To evaluate elastic properties of conduit arteries in asymptomatic patients who have severe chronic aortic regurgitation. METHODS: Twelve healthy volunteers aged 30±1 years (control group) and 14 asymptomatic patients with severe aortic regurgitation aged 29±2 years and left ventricular ejection fraction of 0.61±0.02 (radioisotope ventriculography) were studied. High-resolution ultrasonography was performed to measure the systolic and diastolic diameters of the common carotid artery. Simultaneous measurement of blood pressure enabled the calculation of arterial compliance and distensibility. RESULTS: No differences were observed between patients with aortic regurgitation and the control group concerning age, sex, body surface, and mean blood pressure. Pulse pressure was significantly higher in the aortic regurgitation group compared with that in the control group (78±3 versus 48±1mmHg, P<0.01). Arterial compliance and distensibility were significantly greater in the aortic regurgitation group compared with that in the control group (11.0±0.8 versus 8.1±0.7 10-10 N-1 m4, P=0.01 e and 39.3±2.6 versus 31.1±2.0 10-6 N-1 m², P=0.02, respectively). CONCLUSION: Patients with chronic aortic regurgitation have increased arterial distensibility. Greater vascular compliance, to lessen the impact of systolic volume ejected into conduit arteries, represents a compensatory mechanism in left ventricular and arterial system coupling.

Effects of Sibutramine on the Treatment of Obesity in Patients with Arterial Hypertension

OBJECTIVE: To assess the effects of weight reduction with 10mg of sibutramine or placebo on blood pressure during 24 hours (ambulatory blood pressure monitoring), on left ventricular mass, and on antihypertensive therapy in 86 obese and hypertensive patients for 6 months. METHODS: The patients underwent echocardiography, ambulatory blood pressure monitoring, and measurement of the levels of hepatic enzymes prior to and after treatment with sibutramine or placebo. RESULTS: The group using sibutramine had a greater weight loss than that using placebo (6.7% versus 2.5%; p<0.001), an increase in heart rate (78.3±7.3 to 82±7.9 bpm; p=0.02), and a reduction in the left ventricular mass/height index (105±29.3 versus 96.6±28.58 g/m; p=0.002). Both groups showed similar increases in the levels of alkaline phosphatase and comparable adjustments in antihypertensive therapy; blood pressure, however, did not change. CONCLUSION: The use of sibutramine caused weight loss and a reduction in left ventricular mass in obese and hypertensive patients with no interference with blood pressure or with antihypertensive therapy.

Doppler Echocardiographic Assessment of Pregnant Women with Chronic Arterial Hypertension

OBJECTIVE: To assess structural and functional cardiac changes in asymptomatic pregnant women with chronic arterial hypertension (CAH). METHODS: One hundred pregnant women with CAH underwent conventional Doppler echocardiography. The Student t test was used to compare them with 29 normotensive pregnant women (NT) in their third gestational trimester. RESULTS: Systolic (SBP; mmHg) and diastolic (DBP; mmHg) blood pressure values were higher (p<0.001) in the CAH pregnant women (SBP: 139±19 and DBP: 92± 18) as compared with those of the NT group (SBP: 112±10 and DBP: 74±9). A significant enlargement of the left atrium (4.10±0.48 cm vs 3.6±0.3 cm; p<0.001) and of the left ventricular normalized mass (59.6±19.7 g/cm2,7 vs 41.9±3.4 g/cm2,7; p<0.001) was observed. Cardiac output (CO, L/min) and systolic volume (SV, mL) were significantly higher in the CAH group (CO: 6.0±1.54 vs 4.9±2.1, p<0.01; SV: 77.3±19.8 vs 56.5±25.8, p<0.001). CONCLUSION: Chronic hypertensive pregnant women have structural and functional cardiac changes that justify routine cardiologic assessment, even in the absence of cardiopulmonary symptoms.

Relevance to Home Blood Pressure Monitoring Protocol of Blood Pressure Measurements Taken Before First- Morning Micturition and in the Afternoon

Background: The importance of measuring blood pressure before morning micturition and in the afternoon, while working, is yet to be established in relation to the accuracy of home blood pressure monitoring (HBPM). Objective: To compare two HBPM protocols, considering 24-hour ambulatory blood pressure monitoring (wakefulness ABPM) as gold-standard and measurements taken before morning micturition (BM) and in the afternoon (AM), for the best diagnosis of systemic arterial hypertension (SAH), and their association with prognostic markers. Methods: After undergoing 24-hour wakefulness ABPM, 158 participants (84 women) were randomized for 3- or 5-day HBPM. Two variations of the 3-day protocol were considered: with measurements taken before morning micturition and in the afternoon (BM+AM); and with post-morning-micturition and evening measurements (PM+EM). All patients underwent echocardiography (for left ventricular hypertrophy - LVH) and urinary albumin measurement (for microalbuminuria - MAU). Result: Kappa statistic for the diagnosis of SAH between wakefulness-ABPM and standard 3-day HBPM, 3-day HBPM (BM+AM) and (PM+EM), and 5-day HBPM were 0.660, 0.638, 0.348 and 0.387, respectively. The values of sensitivity of (BM+AM) versus (PM+EM) were 82.6% × 71%, respectively, and of specificity, 84.8% × 74%, respectively. The positive and negative predictive values were 69.1% × 40% and 92.2% × 91.2%, respectively. The comparisons of intraclass correlations for the diagnosis of LVH and MAU between (BM+AM) and (PM+EM) were 0.782 × 0.474 and 0.511 × 0.276, respectively. Conclusions: The 3 day-HBPM protocol including measurements taken before morning micturition and during work in the afternoon showed the best agreement with SAH diagnosis and the best association with prognostic markers.

Blood Pressure Variation Throughout Pregnancy According to Early Gestational BMI: A Brazilian Cohort

Background: The maternal cardiovascular system undergoes progressive adaptations throughout pregnancy, causing blood pressure fluctuations. However, no consensus has been established on its normal variation in uncomplicated pregnancies. Objective: To describe the variation in systolic blood pressure (SBP) and diastolic blood pressure (DBP) levels during pregnancy according to early pregnancy body mass index (BMI). Methods: SBP and DBP were measured during the first, second and third trimesters and at 30-45 days postpartum in a prospective cohort of 189 women aged 20-40 years. BMI (kg/m2) was measured up to the 13th gestational week and classified as normal-weight (<25.0) or excessive weight (≥25.0). Longitudinal linear mixed-effects models were used for statistical analysis. Results: A decrease in SBP and DBP was observed from the first to the second trimester (βSBP=-0.394; 95%CI: -0.600- -0.188 and βDBP=-0.617; 95%CI: -0.780- -0.454), as was an increase in SBP and DBP up to 30-45 postpartum days (βSBP=0.010; 95%CI: 0.006-0.014 and βDBP=0.015; 95%CI: 0.012-0.018). Women with excessive weight at early pregnancy showed higher mean SBP in all gestational trimesters, and higher mean DBP in the first and third trimesters. Excessive early pregnancy BMI was positively associated with prospective changes in SBP (βSBP=7.055; 95%CI: 4.499-9.610) and in DBP (βDBP=3.201; 95%CI: 1.136-5.266). Conclusion: SBP and DBP decreased from the first to the second trimester and then increased up to the postpartum period. Women with excessive early pregnancy BMI had higher SBP and DBP than their normal-weight counterparts throughout pregnancy, but not in the postpartum period.

Progression of Blood Pressure and Cardiovascular Outcomes in Hypertensive Patients in a Reference Center

Background: Hypertension is a public health problem, considering its high prevalence, low control rate and cardiovascular complications. Objective: Evaluate the control of blood pressure (BP) and cardiovascular outcomes in patients enrolled at the Reference Center for Hypertension and Diabetes, located in a medium-sized city in the Midwest Region of Brazil. Methods: Population-based study comparing patients enrolled in the service at the time of their admission and after an average follow-up of five years. Participants were aged ≥18 years and were regularly monitored at the Center up to 6 months before data collection. We assessed demographic variables, BP, body mass index, risk factors, and cardiovascular outcomes. Results: We studied 1,298 individuals, predominantly women (60.9%), and with mean age of 56.7±13.1 years. Over time, there was a significant increase in physical inactivity, alcohol consumption, diabetes, dyslipidemia, and excessive weight. As for cardiovascular outcomes, we observed an increase in stroke and myocardial revascularization, and a lower frequency of chronic renal failure. During follow-up, there was significant improvement in the rate of BP control (from 29.6% to 39.6%; p = 0.001) and 72 deaths, 91.7% of which were due to cardiovascular diseases. Conclusion: Despite considerable improvements in the rate of BP control during follow-up, risk factors worsened and cardiovascular outcomes increased.

Blood Pressure and Hemodynamic Adaptations after a Training Program in Young Individuals with Down Syndrome

Background:Cardiovascular diseases affect people worldwide. Individuals with Down Syndrome (DS) have an up to sixteen-time greater risk of mortality from cardiovascular diseases.Objective:To evaluate the effects of aerobic and resistance exercises on blood pressure and hemodynamic variables of young individuals with DS.Methods:A total of 29 young individuals with DS participated in the study. They were divided into two groups: aerobic training (AT) (n = 14), and resistance training (TR) (n = 15). Their mean age was 15.7 ± 2.82 years. The training program lasted 12 weeks, and had a frequency of three times a week for AT and twice a week for RT. AT was performed in treadmill/ bicycle ergometer, at an intensity between 50%-70% of the HR reserve. RT comprised nine exercises with three sets of 12 repetition-maximum. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and hemodynamic variables were assessed beat-to-beat using the Finometer device before/after the training program. Descriptive analysis, the Shapiro-Wilk test to check the normality of data, and the two-way ANOVA for repeated measures were used to compare pre- and post-training variables. The Pearson’s correlation coefficient was calculated to correlate hemodynamic variables. The SPSS version 18.0 was used with the significance level set at p < 0.05.Results:After twelve weeks of aerobic and/or resistance training, significant reductions in variables SBP, DBP and MBP were observed.Conclusion:This study suggests a chronic hypotensive effect of moderate aerobic and resistance exercises on young individuals with DS.

Heart Rate and Systolic Blood Pressure Variability on Recently Diagnosed Diabetics

Background:Diabetes affects approximately 250 million people in the world. Cardiovascular autonomic neuropathy is a common complication of diabetes that leads to severe postural hypotension, exercise intolerance, and increased incidence of silent myocardial infarction.Objective:To determine the variability of heart rate (HR) and systolic blood pressure (SBP) in recently diagnosed diabetic patients.Methods:The study included 30 patients with a diagnosis of type 2 diabetes of less than 2 years and 30 healthy controls. We used a Finapres® device to measure during five minutes beat-to-beat HR and blood pressure in three experimental conditions: supine position, standing position, and rhythmic breathing at 0.1 Hz. The results were analyzed in the time and frequency domains.Results:In the HR analysis, statistically significant differences were found in the time domain, specifically on short-term values such as standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and number of pairs of successive NNs that differ by more than 50 ms (pNN50). In the BP analysis, there were no significant differences, but there was a sympathetic dominance in all three conditions. The baroreflex sensitivity (BRS) decreased in patients with early diabetes compared with healthy subjects during the standing maneuver.Conclusions:There is a decrease in HR variability in patients with early type 2 diabetes. No changes were observed in the BP analysis in the supine position, but there were changes in BRS with the standing maneuver, probably due to sympathetic hyperactivity.

Estudo do mecanismo da hiperglicemia e da hipertensão arterial, produzidas pelo veneno de escorpião, no cão

In the present paper we studied the mechanism of the hyperglycemia and hypertension evoked by the intravenous injection of scorpion venom (Tityus bahiensis) in the dog. We used 34 dogs, of both sex, weighing between 4.3 to 22 kg. These animals were divided in 3 groups and the following experiments were performed: in the first group (8 dogs) the animals were adrenalectomized after the intravenous injection of chlorpromazine; in the second group (16 dogs) the animals were injected with ganglionic blocking drugs (9.295 Ciba and hexamethonium); in the third group (10 dogs) the naimals were injected with dibenamine, and in 3 of them the adrenal glands were removed. The dogs of each group were injected intravenously with aqueous extract of 2 telsons of scorpion/kg; the average weight of each telson was 6,5 mg. The following results were obtained: 1) The hyperglycemia evoked by scorpion venom, in adrenalectomized dogs, was inhibited by chlorpromazine; 2) Ganglionic blocking drugs (9.295 Ciba and hexamthonium) were inefective as far as the hyperglycemic and pressor effects of venom are concerned; 3) In the animals treated with dibenamine, the venom produced a fall in blood pressure, both in the controle and in the adrenalectomized. The present experiments suggest that the scorpion venom has, besides the central action already described by other investigators, an adrenergic action, very similar to the adrenaline. On basis of our experiments we think that the adrenergic action is responsible, in part, by the productrion of hyperglycemia and hypertension.

Role of endothelium in angiotensin II formation by the rat aorta and mesenteric arterial bed

We investigated the angiotensin II (Ang II)-generating system by analyzing the vasoconstrictor effect of Ang II, angiotensin I (Ang I), and tetradecapeptide (TDP) renin substrate in the absence and presence of inhibitors of the renin-angiotensin system in isolated rat aortic rings and mesenteric arterial beds with and without functional endothelium. Ang II, Ang I, and TDP elicited a dose-dependent vasoconstrictor effect in both vascular preparations that was completely blocked by the Ang II receptor antagonist saralasin (50 nM). The angiotensin converting enzyme (ACE) inhibitor captopril (36 µM) completely inhibited the vasoconstrictor effect elicited by Ang I and TDP in aortic rings without affecting that of Ang II. In contrast, captopril (36 µM) significantly reduced (80-90%) the response to bolus injection of Ang I, without affecting those to Ang II and TDP in mesenteric arteries. Mechanical removal of the endothelium greatly potentiated (70-95%) the vasoconstrictor response to Ang II, Ang I, and TDP in aortic rings while these responses were unaffected by the removal of the endothelium of mesenteric arteries with sodium deoxycholate infusion. In addition, endothelium disruption did not change the pattern of response elicited by these peptides in the presence of captopril. These findings indicate that the endothelium may not be essential for Ang II formation in rat mesenteric arteries and aorta, but it may modulate the response to Ang II. Although Ang II formation from Ang I is essentially dependent on ACE in both vessels, our results suggest the existence of an alternative pathway in the mesenteric arterial bed that may play an important role in Ang II generation from TDP in resistance but not in large vessels during ACE inhibition

Time course of changes in heart rate and blood pressure variability in streptozotocin-induced diabetic rats treated with insulin

Autonomic neuropathy is a frequent complication of diabetes associated with higher morbidity and mortality in symptomatic patients, possibly because it affects autonomic regulation of the sinus node, reducing heart rate (HR) variability which predisposes to fatal arrhythmias. We evaluated the time course of arterial pressure and HR and indirectly of autonomic function (by evaluation of mean arterial pressure (MAP) variability) in rats (164.5 ± 1.7 g) 7, 14, 30 and 120 days after streptozotocin (STZ) injection, treated with insulin, using measurements of arterial pressure, HR and MAP variability. HR variability was evaluated by the standard deviation of RR intervals (SDNN) and root mean square of successive difference of RR intervals (RMSSD). MAP variability was evaluated by the standard deviation of the mean of MAP and by 4 indices (P1, P2, P3 and MN) derived from the three-dimensional return map constructed by plotting MAPn x [(MAPn+1) - (MAPn)] x density. The indices represent the maximum concentration of points (P1), the longitudinal axis (P2), and the transversal axis (P3) and MN represents P1 x P2 x P3 x 10-3. STZ induced increased urinary glucose in diabetic (D) rats compared to controls (C). Seven days after STZ, diabetes reduced resting HR from 380.6 ± 12.9 to 319.2 ± 19.8 bpm, increased HR variability, as demonstrated by increased SDNN, from 11.77 ± 1.67 to 19.87 ± 2.60 ms, did not change MAP, and reduced P1 from 61.0 ± 5.3 to 51.5 ± 1.8 arbitrary units (AU), P2 from 41.3 ± 0.3 to 29.0 ± 1.8 AU, and MN from 171.1 ± 30.2 to 77.2 ± 9.6 AU of MAP. These indices, as well as HR and MAP, were similar for D and C animals 14, 30 and 120 days after STZ. Seven-day rats showed a negative correlation of urinary glucose with resting HR (r = -0.76, P = 0.03) as well as with the MN index (r = -0.83, P = 0.01). We conclude that rats with short-term diabetes mellitus induced by STZ presented modified autonomic control of HR and MAP which was reversible. The metabolic control may influence these results, suggesting that insulin treatment and a better metabolic control in this model may modify arterial pressure, HR and MAP variability

Diverse effects of renal denervation on ventricular hypertrophy and blood pressure in DOCA-salt hypertensive rats

Cardiac hypertrophy that accompanies hypertension seems to be a phenomenon of multifactorial origin whose development does not seem to depend on an increased pressure load alone, but also on local growth factors and cardioadrenergic activity. The aim of the present study was to determine if sympathetic renal denervation and its effects on arterial pressure level can prevent cardiac hypertrophy and if it can also delay the onset and attenuate the severity of deoxycorticosterone acetate (DOCA)-salt hypertension. DOCA-salt treatment was initiated in rats seven days after uninephrectomy and contralateral renal denervation or sham renal denervation. DOCA (15 mg/kg, sc) or vehicle (soybean oil, 0.25 ml per animal) was administered twice a week for two weeks. Rats treated with DOCA or vehicle (control) were provided drinking water containing 1% NaCl and 0.03% KCl. At the end of the treatment period, mean arterial pressure (MAP) and heart rate measurements were made in conscious animals. Under ether anesthesia, the heart was removed and the right and left ventricles (including the septum) were separated and weighed. DOCA-salt treatment produced a significant increase in left ventricular weight/body weight (LVW/BW) ratio (2.44 ± 0.09 mg/g) and right ventricular weight/body weight (RVW/BW) ratio (0.53 ± 0.01 mg/g) compared to control (1.92 ± 0.04 and 0.48 ± 0.01 mg/g, respectively) rats. MAP was significantly higher (39%) in DOCA-salt rats. Renal denervation prevented (P>0.05) the development of hypertension in DOCA-salt rats but did not prevent the increase in LVW/BW (2.27 ± 0.03 mg/g) and RVW/BW (0.52 ± 0.01 mg/g). We have shown that the increase in arterial pressure level is not responsible for cardiac hypertrophy, which may be more related to other events associated with DOCA-salt hypertension, such as an increase in cardiac sympathetic activity

Acute blood volume expansion delays the gastrointestinal transit of a charcoal meal in awake rats

The present study evaluates the effect of blood volume expansion on the gastrointestinal transit of a charchoal meal (2.5 ml of an aqueous suspension consisting of 5% charcoal and 5% gum arabic) in awake male Wistar rats (200-270 g). On the day before the experiments, the rats were anesthetized with ether, submitted to left jugular vein cannulation and fasted with water ad libitum until 2 h before the gastrointestinal transit measurement. Blood volume expansion by iv infusion of 1 ml/min Ringer bicarbonate in volumes of 3, 4 or 5% body weight delayed gastrointestinal transit at 10 min after test meal administration by 21.3-26.7% (P<0.05), but no effect was observed after 1 or 2% body weight expansion. The effect of blood volume expansion (up to 5% body weight) on gastrointestinal transit lasted for at least 60 min (P<0.05). Mean arterial pressure increased transiently and central venous pressure increased and hematocrit decreased (P<0.05). Subdiaphragmatic vagotomy and yohimbine (3 mg/kg) prevented the delay caused by expansion on gastrointestinal transit, while atropine (0.5 mg/kg), L-NAME (2 mg/kg), hexamethonium (10 mg/kg), prazosin (1 mg/kg) or propranolol (2 mg/kg) were ineffective. These data show that blood volume expansion delays the gastrointestinal transit of a charcoal meal and that vagal and yohimbine-sensitive pathways appear to be involved in this phenomenon. The delay in gastrointestinal transit observed here, taken together with the modifications of gastrointestinal permeability to salt and water reported by others, may be part of the mechanisms involved in liquid excess management.

Variations in gastric emptying of liquid elicited by acute blood volume changes in awake rats

We have observed that acute blood volume expansion increases the gastroduodenal resistance to the flow of liquid in anesthetized dogs, while retraction decreases it (Santos et al. (1991) Acta Physiologica Scandinavica, 143: 261-269). This study evaluates the effect of blood volume expansion and retraction on the gastric emptying of liquid in awake rats using a modification of the technique of Scarpignato (1980) (Archives Internationales de Pharmacodynamie et de Therapie, 246: 286-294). Male Wistar rats (180-200 g) were fasted for 16 h with water ad libitum and 1.5 ml of the test meal (0.5 mg/ml phenol red solution in 5% glucose) was delivered to the stomach immediately after random submission to one of the following protocols: 1) normovolemic control (N = 22), 2) expansion (N = 72) by intravenous infusion (1 ml/min) of Ringer-bicarbonate solution, volumes of 1, 2, 3 or 5% body weight, or 3) retraction (N = 22) by controlled bleeding (1.5 ml/100 g). Gastric emptying of liquid was inhibited by 19-51.2% (P<0.05) after blood volume expansion (volumes of 1, 2, 3 or 5% body weight). Blood volume expansion produced a sustained increase in central venous pressure while mean arterial pressure was transiently increased during expansion (P<0.05). Blood volume retraction increased gastric emptying by 28.5-49.9% (P<0.05) and decreased central venous pressure and mean arterial pressure (P<0.05). Infusion of the shed blood 10 min after bleeding reversed the effect of retraction on gastric emptying. These findings suggest that gastric emptying of liquid is subject to modulation by the blood volume.

Intima-media thickness evaluation by B-mode ultrasound: Correlation with blood pressure levels and cardiac structures

The aim of this study was to analyze the thickness of the intima-media complex (IMC) using a noninvasive method. The carotid and femoral common arteries were evaluated by noninvasive B-mode ultrasound in 63 normotensive and in 52 hypertensive subjects and the thickness of the IMC was tested for correlation with blood pressure, cardiac structures and several clinical and biological parameters. The IMC was thicker in hypertensive than in normotensive subjects (0.67 ± 0.13 and 0.62 ± 0.16 vs 0.54 ± 0.09 and 0.52 ± 0.11 mm, respectively, P<0.0001). In normotensive patients, the simple linear regression showed significant correlations between IMC and age, body mass index and 24-h systolic blood pressure for both the carotid and femoral arteries. In hypertensives the carotid IMC was correlated with age and 24-h systolic blood pressure while femoral IMC was correlated only with 24-h diastolic blood pressure. Forward stepwise regression showed that age, body mass index and 24-h systolic blood pressure influenced the carotid IMC relationship (r2 = 0.39) in normotensives. On the other hand, the femoral IMC relationship was influenced by 24-h systolic blood pressure and age (r2 = 0.40). In hypertensives, age and 24-h systolic blood pressure were the most important determinants of carotid IMC (r2 = 0.37), while femoral IMC was influenced only by 24-h diastolic blood pressure (r2 = 0.10). There was an association between carotid IMC and echocardiographic findings in normotensives, while in hypertensives only the left posterior wall and interventricular septum were associated with femoral IMC. We conclude that age and blood pressure influence the intima-media thickness, while echocardiographic changes are associated with the IMC.