Management Of Systemic Hypertension Research Articles

Pathophysiology and Medical Management of Systemic Hypertension in Pregnancy

Hypertension in pregnancy includes a group of distinct disorders that require special consideration in both prevention and pharmacologic treatment. In recent years, there have been few advances regarding the pathophysiology and prevention of preeclampsia or in the recommendations for first-line drug therapy for its hypertensive complications. Similarly, the recommendations for pharmacologic treatment of women with chronic hypertension antedating pregnancy have changed little primarily because first-line medications have the advantage of having had more extensive research experience. Recent clinical trials have demonstrated the efficacy and safety of various second-line drugs for the hypertensive disorders of pregnancy; whether these therapies can eventually replace the standard recommended medications will require more extensive long-term investigation.

ATP-dependent potassium channels as a key target for the treatment of myocardial and vascular dysfunction

The aim of this review is to highlight the most recent and interesting articles on the physiologic properties and functions of ATP-dependent potassium channels in the cardiovascular system and on the role of the potassium channel openers for the treatment of cardiovascular dysfunction. The initial efforts in the development of potassium channel openers focused on the management of systemic hypertension. Lately, the range of possible indications for potassium channel openers has increased to include pulmonary hypertension and stable angina pectoris. The discovery of a connection between the mitochondrial ATP-dependent potassium channels and the phenomenon of cardiac preconditioning created potential new uses for potassium channel openers in myocardial ischemia, inn unstable angina, in preoperative and perioperative settings, and for the preservation of organs for transplant. The most recent data on the physiologic roles of sarcolemmal and mitochondrial ATP-dependent potassium channels and the pharmacology of potassium channel openers in the cardiovascular system are summarized and discussed. Finally, the effects of potassium channel opener drugs including minoxidil, nicorandil, pinacidil, bimakalin, and levosimendan, a dual-action potassium channel opener and calcium sensitizer with inodilator and cardioprotective activity, are discussed.

Betaxolol, a β 1-adrenoceptor antagonist, has an affinity for L-type Ca 2+ channels

The effect of betaxolol on the specific binding of [ 3 H ]diltiazem and [ 3 H ]nitrendipine to rat cortical membranes was examined. Betaxolol inhibited specific [ 3 H ]diltiazem and [ 3 H ]nitrendipine binding with IC 50 values of 19.7 and 46.3 μM, respectively. The effect of betaxolol on L-type Ca 2+ channels showed little stereospecificity, since similar inhibitions of radioligand binding were observed with both racemic betaxolol and l-betaxolol. The dissociation kinetics of [ 3 H ]diltiazem were unaffected by 30 μM betaxolol, whereas it increased the [ 3 H ]nitrendipine dissociation rate, thus suggesting that betaxolol directly interacts with the benzothiazepine binding site and allosterically modulates the dihydropyridine binding site. Carteolol, propranolol and timolol were also found to inhibit both specific [ 3 H ]diltiazem and [ 3 H ]nitrendipine binding to rat cortical membranes, but with less potency than betaxolol. The ability of betaxolol to interact with L-type Ca 2+ channels may have a role in its therapeutic effects in the management of systemic hypertension and in reducing neuronal death as occurring in glaucoma.

Evaluation of the White‐Coat Effect in Cats

The diagnosis and management of systemic hypertension in cats requires a reliable method for measurement of systemic arterial blood pressure (BP) in clinical patients. Unfortunately, the setting of a clinical practice and the act of measuring BP might raise BP and heart rate (HR), an effect referred to as the white‐coat effect in human patients. The purpose of the present study was to determine if a white‐coat effect was experienced by cats. Radiotelemetric implants were used to measure BP and HR in 13 conscious cats in a research colony while undisturbed in their cages and while subjected to simulated visits to a veterinarian's office. The white‐coat effect was taken to be the difference between the overall 24‐hour average value for parameters of BP and HR and the corresponding value during the simulated office visit. A white‐coat effect was observed in cats. In healthy cats, the systolic BP measured during the examination period of the simulated office visit exceeded the 24‐hour average systolic BP by 17.6 ± 1.5 mm Hg. However, marked heterogeneity occurred in the pattern and magnitude of the increase in systolic BP above the 24‐hour baseline and the increase varied between 75.3 and —27.2 mm Hg for the healthy cats. Variation in response to the simulated office visit was observed among cats and among visits by the same cat. During an office visit, the magnitude of the white‐coat effect tended to decrease, but not disappear, over time. The magnitude of the white‐coat effect varied when cats were subjected to 5 repeat office visits, but did not diminish in the group as a whole. The mean increase in systolic BP during the examination (22.3 ± 0.9 mm Hg) was greater (P< .05) in cats with renal insufficiency. Although the heterogeneity of response expected from companion animals might be greater than that observed in these colony cats, these results indicate that veterinarians should carefully consider the white‐coat effect in evaluation of BP in cats. A quiet, undisturbed environment and adequate time for acclimation should be included in the standard protocol for measurements of BP. Because of day‐to‐day variation in the white‐coat effect in individual cats, multiple serial measurements following a standard protocol should provide the best estimate of BP in cats.

Evaluation of the White-Coat Effect in Cats

The diagnosis and management of systemic hypertension in cats requires a reliable method for measurement of systemic arterial blood pressure (BP) in clinical patients. Unfortunately, the setting of a clinical practice and the act of measuring BP might raise BP and heart rate (HR), an effect referred to as the white-coat effect in human patients. The purpose of the present study was to determine if a white-coat effect was experienced by cats. Radiotelemetric implants were used to measure BP and HR in 13 conscious cats in a research colony while undisturbed in their cages and while subjected to simulated visits to a veterinarian's office. The white-coat effect was taken to be the difference between the overall 24-hour average value for parameters of BP and HR and the corresponding value during the simulated office visit. A white-coat effect was observed in cats. In healthy cats, the systolic BP measured during the examination period of the simulated office visit exceeded the 24-hour average systolic BP by 17.6+/-1.5 mm Hg. However, marked heterogeneity occurred in the pattern and magnitude of the increase in systolic BP above the 24-hour baseline and the increase varied between 75.3 and -27.2 mm Hg for the healthy cats. Variation in response to the simulated office visit was observed among cats and among visits by the same cat. During an office visit, the magnitude of the white-coat effect tended to decrease, but not disappear, over time. The magnitude of the white-coat effect varied when cats were subjected to 5 repeat office visits, but did not diminish in the group as a whole. The mean increase in systolic BP during the examination (22.3+/-0.9 mm Hg) was greater (P < .05) in cats with renal insufficiency. Although the heterogeneity of response expected from companion animals might be greater than that observed in these colony cats, these results indicate that veterinarians should carefully consider the white-coat effect in evaluation of BP in cats. A quiet, undisturbed environment and adequate time for acclimation should be included in the standard protocol for measurements of BP. Because of day-to-day variation in the white-coat effect in individual cats, multiple serial measurements following a standard protocol should provide the best estimate of BP in cats.

Calcium antagonists in the management of systemic hypertension

From the Departments of Medicine, The Albert Einstein College of Medicine, Bronx, New York and *Cornell Medical Center, New York, New York, USA.

Effects of amlodipine on blood pressure, heart rate, catecholamines, lipids and responses to adrenergic stimulus

Management of systemic hypertension with calcium antagonists is gaining increasing acceptance. 1 Anti-hypertensive therapy with these agents, however, is limited by frequent adverse effects and need for frequent daily doses. Amlodipine is a new dihydropyridine derivative currently undergoing evaluation for therapy of hypertension. Although qualitatively similar to nifedipine, amlodipine has a longer duration of action and may be useful as a single daily dose. 2 This study evaluated effects of different doses of amlodipine given once daily to patients with mild to moderate hypertension. Its effects on adrenergic response to isometric exercise 3 and plasma levels of catecholamines and lipids were also evaluated.

Calcium antagonists. Clinical use in the treatment of systemic hypertension.

Increased peripheral vascular resistance is the cause of elevated systemic blood pressure in most patients with long standing hypertension. The desired haemodynamic effect in antihypertensive therapy is dilation of the constricted arterioles by a drug that acts directly on the vascular smooth muscle while not affecting the heart or the venous return. Hydralazine, diazoxide and minoxidil act directly on vascular smooth muscle to produce vasodilatation and have been used with variable degrees of success in the long term treatment of hypertension. Their cellular mechanism of dilation is not understood fully, but the ability to chelate certain trace metals required for smooth muscle contraction has been proposed as a possible mechanism of action for these drugs. The calcium antagonists (calcium entry blocking drugs) are a distinct group of compounds that interfere with the normal transmembrane flux of extracellular calcium ions on which vascular tissue depends for contraction or impulse generation. Thus, calcium anti-agonists can reduce the contractile activity of the heart, and promote coronary and systemic vasodilatation. These effects provide the clinical rationale for the use of calcium antagonists in the management of ischaemic heart disease and hypertrophic cardiomyopathy. Since systemic vasodilatation can be expected to reduce elevated arterial blood pressure, interest has focused recently on calcium antagonists in the medical management of systemic hypertension. All the calcium antagonists are able, in low concentrations, to relax the smooth muscle vasculature from coronary, cerebral, mesenteric, and renal arteries. The effects on the myocardium, cardiac impulse tissue, and vascular smooth muscle are different in magnitude, however, depending on the individual agent that is used. Clinical experience in the treatment of hypertension with this class of agents is confined to verapamil, nifedipine, and diltiazem. In this article, the scientific rationale for using calcium antagonists in the treatment of arterial hypertension is explored and the clinical experiences with the different calcium antagonists used in hypertension are reviewed.

Management of systemic hypertension in children.

Management of systemic hypertension in children.