The Role of Salt in Hypertension

There is considerable evidence that salt is an important cause of hypertension. Primitive societies who ingest little or no salt have no hypertension. Also when diets very low in salt such as the rice and fruit diet are given to hypertensive patients, the blood pressure often falls toward normal. Unfortunately, when diets only moderately low in sodium have been given only minor reductions in blood pressure occur. Salt-induced hypertension has been produced in both man and experimental animals. The basic cause of the hypertension is an inability of the kidney to excrete the increased salt. Hemodynamic changes then occur which raise the blood pressure and so excrete the excess salt by pressure diuresis. The ability to excrete salt at normal levels of blood pressure varies from one individual to another. Those who require a higher than normal blood pressure are said to be "salt-sensitive". Those who can excrete excess salt at normal levels of blood pressure are called "salt resistant". The difference may be due to an inherited defect in the kidney to excrete salt. In any event, salt sensitive hypertension is effectively controlled with the administration of diuretics.

Controlling high blood pressure: a simple and effective approach

Fixed-dose combination tablets, such as diuretic plus beta-adrenergic blocking drug or ACE inhibitor are more effective than is any monotherapy. Other advantages include simple titration, low toxicity and reduced expense which encourage better compliance required for optimal blood pressure control.

Studies in hemodynamics and hypertension

This review covers a representative sampling of investigations in hemodynamics and hypertension performed by the author during the period from approximately 1945 to 1980. The hemodynamic studies included a description of changes associated with congestive heart failure and with acute myocardial infarction. These studies emphasized for the first time the importance of left ventricular afterload and of the mobilizable venous reservoir. Other hemodynamic studies included diverse subjects such as the first and only recordings of pulse waves in arteries as small as 200 gammam in diameter, velocity differences between red blood cells and plasma, turbulent blood flow in the ascending aorta, increase in velocity of blood flow of leg veins under compression, rates of transcapillary flow of solutes in humans, and the first use of external arterial pulse wave recordings to assess vascular compliance. Pioneer studies in hypertension included the first use of an antihypertensive drug to treat malignant hypertension and the first report of the treatment of hypertension with a thiazide diuretic.

Department of Veterans Affairs hypertension meeting : a proposal for improved care

A major invitational hypertension meeting was hosted by the Department of Veterans Affairs (VA) in Washington, DC, on May 26 to 28, 1999. It followed a report that only 25% of hypertensive veterans had adequate levels of treated blood pressure and focused on how control of hypertension could be improved both immediately and in the future. After the presentation of brief outlines of 5 unresolved basic science questions, 2 general topics were considered: (1) 30 years of change in hypertension and its treatment and (2) current healthcare delivery mechanisms and how to improve them. Since 1970, the severity of hypertension has decreased, malignant hypertension has disappeared, and the prognostic roles of systolic and diastolic blood pressure have been reversed as hypertension became milder. Five VA Cooperative Studies have provided important data: the 1970 Freis Trial report demonstrated the value of treatment, 2 trials showed that some controlled patients can decrease or even discontinue pharmacological treatment without recrudescent hypertension, a blinded trial was performed on the efficacy of different antihypertensive drugs, and an unblinded trial showed that diuretics and beta-blockers are the most effective agents when caregivers choose the agent and dose. Two healthcare models were considered: (1) the patient-friendly VA Hypertension Screening and Treatment Program that was introduced in 1972, which controls 80% of patients at the goal of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure with diuretics and keeps patients in the program an average of 7.5 years, and (2) the newer primary care health maintenance organization-like model in the VA and throughout the United States. Choosing a regimen and monitoring control of blood pressure and compliance with therapy were discussed. The meeting was closed with 6 general recommendations for improving the care of hypertensive patients.

Diuretics and beta-blockers do not have adverse effects at 1 year on plasma lipid and lipoprotein profiles in men with hypertension. Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

BACKGROUND

Concern based on the reported short-term adverse effects of antihypertensive agents on plasma lipid and lipoprotein profiles (PLPPs) has complicated the therapy for hypertension.

OBJECTIVE

To compare the long-term (1-year) effects of 6 different antihypertensive drugs and placebo on PLPPs in a multicenter, randomized, double-blind, parallel-group clinical trial in 15 US Veterans Affairs medical centers.

PATIENTS AND METHODS

A total of 1292 ambulatory men, 21 years or older, with diastolic blood pressures (DBPs) ranging from 95 to 109 mm Hg taking placebo were randomized to receive placebo or 1 of 6 antihypertensive drugs: hydrochlorothiazide, atenolol, captopril, clonidine, diltiazem, or prazosin. After drug titration, patients with a DBP of less than 90 mm Hg were followed up for 1 year. Plasma lipids and lipoprotein profiles were determined at baseline, after initial titration, and at 1 year.

RESULTS

After 8 weeks on a regimen of hydrochlorothiazide, increases of 3.3 mg/dL (0.09 mmol/L) in total cholesterol and 2.7 mg/dL in apolipoprotein B were significantly different (P< or =.05) from decreases of 9.3 mg/dL in total cholesterol and 5.4 mg/dL in ApoB levels while receiving prazosin but not from placebo. Patients achieving positive DBP control using hydrochlorothiazide (responders) showed no adverse changes in PLPPs, whereas nonresponders exhibited increases in triglycerides, total cholesterol, and low-density lipoprotein cholesterol levels. Plasma lipids and lipoprotein profiles did not change significantly among treatment groups after 1 year except for minor decreases in high-density lipoprotein 2 levels using hydrochlorothiazide, clonidine, and atenolol.

CONCLUSIONS

None of these 6 antihypertensive drugs has any long-term adverse effects on PLPPs and, therefore, may be safely prescribed. Previously reported short-term adverse effects from using hydrochlorothiazide are limited to nonresponders.

Current status of diuretics, beta-blockers, alpha-blockers, and alpha-beta-blockers in the treatment of hypertension

The article describes the current status of four main antihypertensives. Diuretics are making a bit of a comeback after seeing their popularity wane during the 1980s. beta-blockers also saw a bit of a popularity decrease in the 1980s due to some adverse side effects which the author feels were somewhat exaggerated. alpha-blockers have yet to be particularly successful in the treatment of hypertension, due to adverse side effects. alpha-beta-blockers appear to hold significant promise in the further treatment of hypertension.

Comparison of plasma lipid and lipoprotein profiles in hypertensive black versus white men. Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

An abnormal plasma lipid and lipoprotein profile is an independent and strong predictor of mortality and morbidity from coronary artery disease (CAD). We report on plasma lipid and lipoprotein profiles with respect to race, age, obesity, blood pressure (BP), smoking, and drinking history in 1,292 male veterans with a diastolic BP of 95 to 109 mm Hg while off antihypertensive medications. Blacks had 24% (p <0.001) lower triglycerides than whites. In contrast, the following parameters were higher in blacks than in whites by the indicated percentages: high-density lipoprotein (HDL) cholesterol, 16% (p <0.001); HDL2 cholesterol, 36% (p <0.001); apolipoprotein (Apo) A1, 8% (p <0.001); HDL/low-density lipoprotein (LDL), 18% (p = 0.018); HDL2/LDL, 36% (p = 0.031); HDL2/HDL3, 21% (p <0.001); and Apo A1/Apo B, 15% (p <0.001). Triglycerides were unchanged up to age 60, but were lower by 24% (p <0.001) in those aged > or = 70. Apo A1 levels were higher (p <0.001), whereas LDL cholesterol was lower (p <0.008) in moderate alcohol consumers versus abstainers. Triglycerides were higher (p <0.001), whereas HDL, HDL2 cholesterol, and Apo A1 were lower (p <0.001) with increasing obesity. Moderate alcohol consumption had a strong favorable effect on HDL, HDL2, and HDL3 cholesterol among subjects of normal weight, but this effect was diminished in obese subjects. Total and LDL cholesterol were higher by 6.4% (p = 0.001) and 9.4% (p <0.003), respectively, whereas HDL cholesterol remained unchanged in those with diastolic BP of 105 to 109 mm Hg versus those with diastolic BP of 95 to 99 mm Hg. We conclude that hypertensive black men have lipid and lipoprotein profiles indicative of less CAD risk than white men. Chronic moderate alcohol consumption correlates with a favorable plasma lipid and lipoprotein profile in normal, but not obese, men. Obesity is associated with an adverse plasma lipid and lipoprotein profile. Thus, race, alcohol intake, and obesity may be important modifiers of CAD in untreated hypertensive men.

Current drug treatment and treatment patterns with antihypertensive drugs

The 4 major classes of antihypertensive drugs are diuretics, beta-blockers, ACE inhibitors and calcium antagonists. The diuretics have recently regained prominence, largely due to the results of recent controlled trials. These trials in elderly patients demonstrated that low-dose diuretics were effective not only in preventing stroke but also in greatly reducing coronary-related events. Diuretics also decrease left ventricular mass more than the other major drug classes. In addition, they are the most effective drugs for use in combination therapy. By contrast, the safety of calcium antagonists has recently been questioned because of report of increased coronary morbidity and mortality. However, these adverse events may be restricted to the short-acting preparations, especially nifedipine, which causes cardiac stimulation. ACE inhibitors, like beta-blockers, are not only effective in reducing blood pressure, particularly when combined with a diuretic, but also improve angina and decrease postinfarction mortality. They also benefit congestive heart failure, stabilise or improve renal function in hypertensive and diabetic nephropathy and reduce albuminuria. Beta-Blockers are especially effective in reducing sudden cardiac death in patients with coronary heart disease, particularly in postinfarction patients. Final proof of the relative effectiveness of these drugs in preventing morbidity and mortality must await the outcome of large comparative trials currently under way. A recent national survey in the US found that more than 75% of hypertensive patients did not have their hypertension completely controlled. Possible reasons for this disturbing statistic are discussed along with suggestions for improvement.

Response to a second single antihypertensive agent used as monotherapy for hypertension after failure of the initial drug. Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

BACKGROUND

An important issue in clinical practice is how to treat patients whose blood pressure does not respond to the first antihypertensive drug selected.

OBJECTIVE

To analyze the antihypertensive response of patients who had failed to achieve their diastolic blood pressure goal (< 90 mm Hg at the end of 8 to 12 weeks of titration) with one of six randomly allocated drugs or placebo to the random allocation of an alternate drug.

METHODS

We initially randomized 1292 men with diastolic blood pressure of 95 to 109 mm Hg to treatment with hydrochlorothiazide, atenolol, captopril, clonidine hydrochloride, diltiazem hydrochloride (sustained release), prazosin hydrochloride, or placebo. Of 410 men in whom initial treatment failed, 352 qualified for randomization to the alternate drug.

RESULTS

Of the 352 patients, 173 (49.1%) achieved their goal diastolic blood pressure, in 133 (37.8%) the alternate drug failed, and 46 (13.1%) left the study for various reasons. Overall response rates were as follows: diltiazem, 63%; clonidine, 59%; prazosin, 47%; hydrochlorothiazide, 46%; atenolol, 41%; and captopril, 37%. The best response rate for patients in whom hydrochlorothiazide failed was achieved with diltiazem (70%); after atenolol failure, clonidine (86%); after captopril failure, prazosin (54%); after clonidine failure, diltiazem (100%); after diltiazem failure, captopril (67%); and after prazosin failure, clonidine (53%). The combined response rate for patients initially randomized to an active treatment was 76.0%, which is similar to that achieved by the combination of two drugs in previous studies.

CONCLUSIONS

We conclude that sequential single-drug therapy is a rational approach for treatment of hypertension in patients in whom initial drug therapy has failed.

The efficacy and safety of diuretics in treating hypertension

The efficacy of thiazides and related diuretics in preventing most of the complications of hypertension has been conclusively documented in long-term controlled trials. Among their adverse effects, thiazides may induce a short-term increase in serum cholesterol levels. However, the elevation returns to pretreatment levels during long-term therapy. In addition, long-term treatment with thiazides is not associated with an elevation of blood glucose levels or an increased incidence of diabetes. Because the long-term controlled trials have shown that thiazides provide more protection against stroke than against coronary heart disease events, it is possible that the difference may be caused by adverse effects of the diuretics. In three of four recent trials that used low doses of thiazides plus potassium-sparing diuretics, the number of sudden deaths was reduced more than in other trials that used high doses of diuretics alone. A recent case-control study also found that small doses of diuretics combined with potassium-sparing drugs were associated with a reduced number of sudden deaths compared with high doses used alone. Although these results suggest that small doses reduce the risk for sudden death more than do large doses, they cannot be regarded as conclusive. A randomized double-blind trial comparing low and high doses of thiazide diuretics and potassium-sparing drugs must be done. For now, however, small doses seem prudent for treating hypertension.

Prognosis in elderly hypertensive patients

Hypertension is much more prevalent in the aged than in younger individuals and the risk of cardiovascular complications increases with age. Treatment of hypertension reduces this risk significantly. The benefits of treatment in improving prognosis are at least as striking in elderly as in young and middle-aged hypertensive patients.

Single-drug therapy for hypertension in men. A comparison of six antihypertensive agents with placebo. The Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

BACKGROUND

Characteristics such as age and race are often cited as determinants of the response of blood pressure to specific antihypertensive agents, but this clinically important issue has not been examined in sufficiently large trials, involving all standard treatments, to determine the effect of such factors.

METHODS

In a randomized, double-blind study at 15 clinics, we assigned 1292 men with diastolic blood pressures of 95 to 109 mm Hg, after a placebo washout period, to receive placebo or one of six drugs: hydrochlorothiazide (12.5 to 50 mg per day), atenolol (25 to 100 mg per day), captopril (25 to 100 mg per day), clonidine (0.2 to 0.6 mg per day), a sustained-release preparation of diltiazem (120 to 360 mg per day), or prazosin (4 to 20 mg per day). The drug doses were titrated to a goal of less than 90 mm Hg for maximal diastolic pressure, and the patients continued to receive therapy for at least one year.

RESULTS

The mean (+/- SD) age of the randomized patients was 59 +/- 10 years, and 48 percent were black. The average blood pressure at base line was 152 +/- 14/99 +/- 3 mm Hg. Diltiazem therapy had the highest rate of success: 59 percent of the treated patients had reached the blood-pressure goal at the end of the titration phase and had a diastolic blood pressure of less than 95 mm Hg at one year. Atenolol was successful by this definition in 51 percent of the patients, clonidine in 50 percent, hydrochlorothiazide in 46 percent, captopril in 42 percent, and prazosin in 42 percent; all these agents were superior to placebo (success rate, 25 percent). Diltiazem ranked first for younger blacks (< 60 years) and older blacks (> or = 60 years), among whom the success rate was 64 percent, captopril for younger whites (success rate, 55 percent), and atenolol for older whites (68 percent). Drug intolerance was more frequent with clonidine (14 percent) and prazosin (12 percent) than with the other drugs.

CONCLUSIONS

Among men, race and age have an important effect on the response to single-drug therapy for hypertension. In addition to cost and quality of life, these factors should be considered in the initial choice of a drug.

Adverse effects of diuretics

Analysis of the available evidence indicates that diuretics do not increase coronary heart disease morbidity and mortality. The multiclinic trials supporting the cardiotoxicity hypothesis are few in number and flawed in design. The majority of the trials, including the well designed trials, indicate no excess of coronary heart disease (CHD) events in diuretic-treated patients compared with those given other drugs or placebo. Recent studies indicate no increase in cardiac arrhythmias after diuretic treatment. Also, although depletion of intracellular potassium and magnesium occurs in patients with congestive heart failure even without diuretics, intracellular concentration of these ions is not significantly reduced by diuretics in patients with uncomplicated hypertension. Modest elevations of serum cholesterol may occur during the first 6 to 12 months of treatment with thiazide diuretics. However, after this time these elevations fall to or below the pretreatment level. The fall may be greater in patients receiving other drugs but the differences are small and their clinical significance is questionable. The incidences of hyperglycaemia and diabetes were only minimally increased in long term clinical trials while the importance of hyperinsulinism and insulin resistance in causing CHD remains unproven in patients. Thiazides remain, therefore, a safe and effective treatment for patients with hypertension.

Treatment of hypertension in the elderly. III. Response of isolated systolic hypertension to various doses of hydrochlorothiazide: results of a Department of Veterans Affairs cooperative study. Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

In a double-blind randomized study, we evaluated the effects of 25 mg vs 50 mg of hydrochlorothiazide in 51 elderly patients (aged 68.9 +/- 7.0 years) with isolated systolic hypertension (blood pressure, 160 to 239 mm Hg systolic and less than 90 mm Hg diastolic). Dose levels could be increased to twice daily to control blood pressure. The reductions in blood pressure (25.4/6.8 mm Hg and 28.9/7.4 mm Hg) and proportion of patients in whom blood pressure was controlled (78% and 89%) were similar in the lower- and higher-dose groups during the titration phase. However, serum potassium level was reduced more in the higher-dosage (0.57 mmol/L) than the lower-dosage (0.17 mmol/L) group. There were no significant changes in blood pressure during a 24-week maintenance phase. No patient required withdrawal from the study because of adverse effects, and cognitive-behavioral function was well preserved. We conclude that hydrochlorothiazide is effective and well tolerated in older patients with isolated systolic hypertension, many of whom may be effectively treated with 25 mg of hydrochlorothiazide once daily.

Veterans Administration Cooperative Study Group on Hypertensive Agents: effects of age on treatment results

In three double-blind studies of 1,396 hypertensive patients, the age-related effects of hydrochlorothiazide or bendroflumethazide were compared with those of propranolol, nadolol, or captopril, given singly or in combination with a thiazide. Patients in each treatment group were divided into those aged 55 to 69 years and those aged under 55. Whereas no age-related differences were apparent with propranolol, nadolol alone, or captopril alone, in all three studies the blood pressure-reducing effect was found to be greater in the older group of thiazide-treated patients than in the younger thiazide-treated group. The antihypertensive drugs studied are at least as effective in older as in younger hypertensive patients and the antihypertensive response with diuretics is greater in older patients than in younger patients.

The cardiotoxicity of thiazide diuretics: review of the evidence

Careful consideration of all relevant scientific evidence and a critical assessment of data quality show that thiazide diuretics are not cardiotoxic. Of 12 reported trials only two recorded more coronary heart disease events in thiazide-treated patients than in controls. One of these two was a subgroup of a larger study (Heart Attack Prevention in Primary Hypertension, HAPPHY) which found no difference between thiazide-treated and beta-blocker-treated patients. The other, the Oslo study, was too small to allow valid conclusions. Results from a subgroup in the Multiple Risk Factor Intervention Trial (MRFIT) that appeared to supply evidence for thiazide-related cardiotoxicity are suspect when examined critically. Further evidence from 24- to 28-h ECG monitoring does not support the hypothesis that thiazide diuretics, either in the presence or absence of hypokalemia, increase the frequency or severity of ventricular arrhythmias. Reports of a thiazide-induced intracellular magnesium deficiency as a cause of ventricular arrhythmias have also not been confirmed; the development of arrhythmias in acute myocardial infarction appears to be due to an increase in catecholamine levels rather than hypokalemia. There appears to be little evidence to support the assumption that long-term use of thiazide diuretics aggravates or accelerates atherosclerosis of the coronary arteries; any fall in serum cholesterol appears to be transient. For the great majority of patients with uncomplicated hypertension, without a previous myocardial infarction, congestive heart failure, diabetes mellitus or gout, thiazide diuretics appear to be both safe and effective antihypertensive agents.

Treatment of hypertension in the elderly: I. Blood pressure and clinical changes. Results of a Department of Veterans Affairs Cooperative Study

We compared the efficacy and adverse effects of antihypertensive drug regimens in 690 men past age 60 with diastolic blood pressure 90-114 mm Hg and systolic blood pressure less than 240 mm Hg. They received either a low (25-50 mg) or high (50-100 mg) dose of hydrochlorothiazide daily. Of 644 patients who completed the hydrochlorothiazide titration, 375 (58.2%) were responders (diastolic blood pressure less than 90 and less than or equal to 5 mm Hg below baseline) and 92.8% of these completed a 6-month maintenance period. Blood pressure was reduced from 157.6/98.5 mm Hg by 18.3/9.5 mm Hg with low dose hydrochlorothiazide and by 20.4/9.6 mm Hg with high dose hydrochlorothiazide; more patients achieved goal blood pressure with the high dose. Whites and blacks responded equally. Serum potassium less than 3.5 mmol/l occurred in 104 of 321 (32.3%) of the high dose versus 62 of 333 (18.6%) of the low dose hydrochlorothiazide patients. The 269 nonresponders to hydrochlorothiazide were randomly assigned in a double-blind study to receive hydralazine, methyldopa, metoprolol, or reserpine in addition to hydrochlorothiazide; 79.2% responded to the addition of the second drug and 87.3% of these completed a 6-month maintenance phase. Overall, there were no significant efficacy differences among the step 2 regimens. We conclude that the lower dose of hydrochlorothiazide was nearly as effective as the higher dose, and the addition of a second drug was effective and generally well tolerated in elderly patients.

Treatment of hypertension in the elderly: II. Cognitive and behavioral function. Results of a Department of Veterans Affairs Cooperative Study

This study was designed to determine whether blood pressure reduction, per se, causes adverse effects on cognitive and behavioral function in elderly hypertensive patients. Men with mild-to-moderate diastolic hypertension who had passed their 60th birthday were entered into the trial. After a placebo washout period, they were assigned in a randomized, double-blind manner to one of two groups receiving hydrochlorothiazide (either 25 mg once or twice daily or 50 mg once or twice daily). Responders entered a 1-year maintenance period. Nonresponders were randomly assigned to double-blind treatment with hydralazine, methyldopa, metoprolol, or reserpine added to the diuretic therapy. During the placebo and treatment periods, patients underwent a battery of psychometric tests designed to assess cognitive function, motor skills, memory, and affect. A separate questionnaire assessed the patient's ability to perform activities of daily living. A subset of patients blindly being treated with placebo received the same battery of tests as a control for practice effect. The results showed that there was similar improvement on the psychometric tests between those patients whose blood pressure was successfully reduced and the placebo-treated control group. Therefore, the practice effect did not obscure a true deterioration in function. There were no substantive differences between the lower and higher doses of diuretic or among the four drugs added to the diuretic, although there were qualitative differences in side effects. We conclude that blood pressure reduction, per se, does not adversely affect cognitive and behavioral function in elderly hypertensive patients and that antihypertensive treatment is safe and effective in these patients.

Diuretic therapy and exercise in patients with systemic hypertension

Twenty patients with uncomplicated systemic hypertension underwent treadmill testing twice during placebo treatment and twice during hydrochlorothiazide treatment. Data were collected at rest, at peak exercise and 10 min after exercise. Serum potassium, magnesium and plasma catecholamines increased significantly with exercise. There was no rebound hypokalaemia during the recovery period. Occasional ventricular premature complexes were recorded in all phases of the study. However, there was no difference in the frequency or complexity of arrhythmias between the placebo and the treatment periods.

Potassium restoration in hypertensive patients made hypokalemic by hydrochlorothiazide

Among 447 hypertensive patients, most with a history of diuretic-induced hypokalemia, 252 developed diuretic-induced hypokalemia while receiving hydrochlorothiazide, 50 mg/d. In a randomized study we evaluated the efficacy of three drug regimens in restoring potassium levels while maintaining blood pressure control: hydrochlorothiazide (50 mg/d) plus potassium supplement (20 mmol/d); hydrochlorothiazide (50 mg/d) plus potassium supplement (40 mmol/d); or hydrochlorothiazide (50 mg/d) with triamterene (75 mg/d) in one combination tablet. In all groups, mean serum levels of potassium rose within 1 week and showed no further change thereafter. However, the hydrochlorothiazide/triamterene and hydrochlorothiazide plus 40 mmol of potassium regimens were significantly more effective in restoring serum potassium levels than was the hydrochlorothiazide plus 20 mmol of potassium regimen. A significant increase in magnesium levels was observed only in the group treated with the hydrochlorothiazide/triamterene combination. Each regimen provided continued control of mild to moderate hypertension.

Effects of diuretic therapy and exercise-related arrhythmias in systemic hypertension

The effect of aerobic exercise on cardiac arrhythmias, plasma catecholamines, potassium and magnesium in patients with systemic hypertension was assessed. Twenty patients (age 54 +/- 8 years) with uncomplicated hypertension underwent exercise treadmill testing twice while receiving placebo and twice while receiving hydrochlorothiazide 100 mg daily. Blood samples for electrolytes and catecholamines were obtained at rest, at peak exercise and 10 minutes after exercise. There were no substantial differences comparing the first to the second placebo phase or the first to the second treatment period. As expected, hydrochlorothiazide treatment caused a significant decrease in serum potassium (4.00 +/- 0.44 to 3.32 +/- 0.49 mEq/liter, p less than 0.001). Serum magnesium did not change with treatment. Serum potassium, serum magnesium and plasma catecholamines increased significantly with exercise. No rebound hypokalemia occurred during recovery. Occasional ventricular premature contractions were noted at rest during all phases of the study, with only a slight increase in frequency during exercise. Couplets were noted only rarely. No difference in the frequency or complexity of arrhythmias was noted between placebo and treatment periods. Diuretic therapy or diuretic-induced hypokalemia has no profound effect on cardiac arrhythmias during or after exercise in patients with uncomplicated systemic hypertension.

Humoral Na+-K+ pump inhibitory activity in essential hypertension and in normotensive subjects after acute volume expansion

Plasma from black male patients with essential hypertension was bioassayed for vascular Na+-K+ pump inhibitory activity. Halves of the same rat tail artery were incubated for two hours in boiled plasma supernates from a hypertensive patient and a paired age-, sex-, and race-matched normotensive subject and then ouabain-sensitive 86Rb uptake was measured. Ouabain-sensitive 86Rb uptake by their leukocytes was also measured. Eighteen pairs of subjects were studied. The uptakes were not significantly different in the hypertensive patients and control subjects. However, when we selected from the eighteen hypertensive patients, nine with low plasma renin activity on the day of the study, uptakes were reduced in the hypertensive patients relative to the paired control subjects. We also assayed plasma supernates from normotensive black and white male subjects before and after acute volume expansion (2.5 L saline IV + 1.5 L distilled water orally over a three-hour period) and from paired normotensive subjects before and after sham volume expansion and obtained a positive bioassay in the expanded subjects both on intraindividual and interindividual comparisons. These studies demonstrate increased vascular Na+-K+ pump inhibitory activity in the plasma of black male patients with low renin essential hypertension and in the plasma of normotensive subjects after acute volume expansion. The findings suggest that the inhibitory activity in the hypertensive subjects' plasma is related to volume expansion, relative or absolute.

Effects of reduction in drugs or dosage after long-term control of systemic hypertension

The possibility of discontinuing--compared to reducing--antihypertensive drug treatment was investigated in 606 male hypertensive patients with entry diastolic blood pressure (BP) in the range of 90 to 114 mm Hg. Diastolic BP was controlled at less than 90 mm Hg with 1 of 4 regimens: low dose hydrochlorothiazide (HCTZ), 25 mg twice daily; high dose HCTZ, 50 mg twice daily; or high dose HCTZ plus a low or high dose of a step II drug (propranolol, clonidine or reserpine). After 6 months of treatment that controlled BP, dosages were reduced in two-thirds of the patients. In those patients receiving low dose HCTZ and randomized to dose reduction, antihypertensive drugs were completely discontinued. Although approximately half of these patients remained normotensive for the first 6 months, a significantly greater proportion had elevation of BP compared to the control group, which continued to receive treatment (p less than 0.0001). In the high dose HCTZ drug group, the proportion of patients remaining normotensive did not differ among those stepped down to low dose HCTZ and the fully treated control group. While not achieving significance the trend was similar with the step II regimens. Although some patients remained normotensive after discontinuation of step II drugs, a greater proportion returned to elevated BP than when step II dosage was unchanged. Therefore, while stopping therapy may be effective in some patients, a decreased dosage is significantly more effective as a method for maintaining an antihypertensive effect. Decreasing drug dosages offers the dual benefit of minimizing side effects and reducing drug costs.

Exercise blood pressure response and left ventricular hypertrophy

Although hypertension is the major cause of left ventricular hypertrophy (LVH), numerous studies failed to demonstrate a close correlation between resting blood pressure (BP) and degree of LVH. Some authors have shown better correlation between BP at work and left ventricular mass (LV mass), whereas other studies supported an association between catecholamines or angiotensin II and LV mass. In this study we investigated the relationship of resting and exercise BP and catecholamines to the degree of LVH. Nineteen patients with established mild to moderate hypertension were studied. Blood pressure was measured following a ten-minute rest and every three minutes during exercise using a Bruce protocol. Electrolytes, epinephrine (EP), and norepinephrine (NE) were measured at rest, at peak exercise, and at ten-minutes postexercise. Resting BP averaged 154 +/- 24/99 +/- 9 mm Hg and at three minutes of exercise 195 +/- 30/101 +/- 6 (P less than .001). Resting EP was 51 +/- 20 pg/mL, NE 314 +/- 187, and at peak exercise EP was 107 +/- 61 (P less than .001) and NE 1016 +/- 566 (P less than .001). The average LV mass was 277 +/- 85 g. A significant correlation was found only between systolic BP at three minutes of exercise and LV mass (r = .479, P less than .04). No other variable correlated significantly with LV mass. These data suggest that systolic BP achieved at low level of exercise (5 mets), corresponding to usual daily activities, may be the most important determinant of LVH in patients with hypertension.

Cigarette smoking interferes with treatment of hypertension

We retrospectively analyzed two studies to determine whether smoking affected the treatment of hypertension. In a study of the effects of propranolol hydrochloride (a hepatically metabolized beta-blocker) vs hydrochlorothiazide, 108 smokers and 232 nonsmokers were randomized to the propranolol treatment group. The propranolol-treated smokers tended to be younger, taller, thinner, and wre more likely to be black. This group also had an initial blood pressure reduction (+/- SD) of -7.9 +/- 12.9/-8.7 +/- 8.4 mm Hg compared with -10.7 +/- 13.0/-10.9 +/- 7.1 mm Hg for the nonsmokers. Blood pressure increased less during the one-year maintenance period for the nonsmokers. However, when analyzed by race, this effect was seen in blacks, but not in whites. Diastolic blood pressure tended to be reduced more in nonsmokers (vs smokers) receiving hydrochlorothiazide (-12.1 +/- 6.7 vs -10.7 +/- 6.7 mm Hg, respectively). The second study compared the effects of nadolol (a renally excreted beta-blocker) with bendroflumethiazide. There were no significant effects on blood pressure for either of these drugs. In both studies, there was a greater tendency for smokers to be terminated from the study irrespective of drug group. We conclude that cigarette smoking does interfere with the treatment of hypertension in general, and especially with reduction of blood pressure by propranolol in black patients.

Volume (weight) loss and blood pressure response following thiazide diuretics

Correlations were made between weight change (as an index of volume loss) and blood pressure (BP) reduction before and after hydrochlorothiazide treatment. A total of 343 patients with mild to moderate hypertension (95-114 mm Hg) received hydrochlorothiazide alone. The diuretic was titrated from 50 to 100 to 200 mg daily as needed until the diastolic BP fell below 90 mm Hg (goal BP) or side effects supervened. Of the 305 patients who completed the 10-week titration period, 65% attained goal BP. The effective dose of hydrochlorothiazide in 52% of these responders was 50 mg/day, and this was associated with weight loss averaging 1.58 kg. An additional 29% achieved goal BP with a similar degree of weight loss, but they required double the dose, or 100 mg/day. The remaining 19% of responders required significantly greater weight reductions averaging 3.14 kg to achieve goal BP, which necessitated hydrochlorothiazide, 200 mg/day. More blacks than whites attained goal BP despite similar degrees of weight loss in the two races. Plasma renin activity was initially higher in whites than in blacks and rose significantly more in blacks and whites requiring the greatest volume losses and the highest dose of hydrochlorothiazide to attain goal BP. Nonresponders had less weight loss than responders. Thus, diuretic dose requirements vary in different patients and are related either to different volume losses in response to a given dose or to different degrees of BP reduction in response to the same volume loss.

Thiazide therapy is not a cause of arrhythmia in patients with systemic hypertension

Forty-four patients with uncomplicated systemic hypertension underwent 48-hour electrocardiographic monitoring before and after four weeks of treatment with hydrochlorothiazide, 100 mg daily. Plasma potassium concentration decreased from 4.07 +/- 0.26 mmol/L (4.07 +/- 0.26 mEq/L) to 3.36 +/- 0.44 mmol/L (3.36 +/- 0.44 mEq/L). The average number of premature ventricular contractions, couplets, or ventricular tachycardia episodes did not change significantly. Twenty patients had more than minimal ventricular ectopy (class 2 to 5) before and 17 after diuretic therapy. Further analysis revealed that following diuretic therapy, neither patients with plasma potassium levels of 3.4 mmol/L or less (less than or equal to 3.4 mEq/L) nor patients with left ventricular hypertrophy had increased ectopy as compared with baseline. At baseline, patients with left ventricular hypertrophy had more arrhythmias than patients without. We conclude that the results of this study provide no evidence that diuretic therapy or diuretic-induced hypokalemia results in increased ventricular ectopy, and that patients with left ventricular hypertrophy may have more ventricular ectopy than patients without, but these arrhythmias are not adversely effected by diuretic therapy.

Age and antihypertensive drugs (hydrochlorothiazide, bendroflumethiazide, nadolol and captopril)

Three double-blind Veterans Administration Cooperative Studies are reviewed to determine age-related changes in response to antihypertensive agents. In the first study 312 patients received hydrochlorothiazide titrated from 25 to 100 mg twice daily to lower diastolic blood pressure (BP) to less than 90 mm Hg. Of 121 patients aged 55 to 65 the decrease in BP averaged -21.8/-12.9 mm Hg, while in the 191 patients younger than 55 the reduction averaged -15.7/-11.5 mm Hg (p less than 0.001; p = 0.048, respectively). Both systolic and diastolic BP reductions averaged significantly more in older whites; in older blacks it was systolic BP only. An additional 298 patients received titrated doses of propranolol alone. In this group there were no significant differences in BP response between younger patients and patients aged 55 to 65 except in the subgroup of white patients older than 60, in whom the systolic reduction was significantly less than in the younger patients. In a second study of bendroflumethiazide alone and with nadolol, systolic BP decreased more in older than in younger patients but there was no age-related reduction with nadolol alone. In the third trial captopril was first given alone and later with hydrochlorothiazide. There were no age-related differences with captopril alone, but after the addition of hydrochlorothiazide there was a trend toward a greater antihypertensive response in the patients aged 55 to 69. Thus, responsiveness of older patients varies with the type of antihypertensive drug. Age appears to increase the antihypertensive response to thiazide diuretics but not to beta-adrenergic blocking drugs or to captopril.

Is low-dose hydrochlorothiazide effective?

In a double-blind crossover study, 13 patients with pretreatment diastolic blood pressure between 95 and 109 mm Hg received nadolol, 80 mg/day, plus placebo of hydrochlorothiazide and nadolol, plus three different doses of active hydrochlorothiazide. Patients remained on each active regimen for 3 weeks, with an intervening placebo period of 2 to 4 weeks. With 12.5 mg of hydrochlorothiazide daily plus nadolol, there was no greater reduction of blood pressure than with nadolol alone. A dose of 25 mg of hydrochlorothiazide was associated with a significantly greater decrease in systolic but not diastolic pressure, as compared with nadolol alone. A significantly greater reduction in both systolic and diastolic blood pressure was obtained only with the 50 mg/day dose of hydrochlorothiazide. Extension to 6 weeks of treatment with 12.5 mg/day failed to lower the blood pressure more than the level seen at 3 weeks. These results suggest that in combination with nadolol, 12.5 mg of hydrochlorothiazide per day has no significant antihypertensive effect. There was no evidence of a flat dose-response curve in the daily dose range of 12.5 to 50 mg. For most patients, a dose of 50 mg of hydrochlorothiazide was required to lower both systolic and diastolic blood pressure significantly below the level obtained with nadolol alone.

How dangerous are diuretics?

The proposal that thiazide diuretics may increase cardiovascular risk receives no support from recent data. Current evidence does not indicate that diuretic-induced hypokalaemia is associated with increased ventricular arrhythmias. This evidence includes continuous electrocardiographic monitoring--which is the most sensitive technique for quantitating cardiac arrhythmias. In contrast to earlier reports, more recent studies found no evidence for increased arrhythmias during the period of hypokalaemia, or for decreased arrhythmic activity after correction of hypokalaemia. Similarly, studies claiming increased sudden death in patients on diuretic treatment have not been substantiated by the results of other large-scale trials. Elevation of serum cholesterol concentrations with thiazide appears to be a short term phenomenon since most studies indicate the elevation reverts to baseline during long term treatment. Thiazide diuretics remain as one of our most effective antihypertensive agents. Fears of their increasing the incidence of ventricular arrhythmias due to hypokalaemia, or constituting a risk factor for atherosclerosis by elevating serum cholesterol concentrations, appear largely unsubstantiated.

Effectiveness of potassium chloride or triamterene in thiazide hypokalemia

Potassium chloride was compared with triamterene in a crossover trial involving 16 hypertensive patients with overt diuretic-induced hypokalemia. Potassium chloride, 24 to 96 mEq/day, normalized the plasma potassium (PK) level at 3.5 mEq/L or more in only eight of the patients. The average increase in PK level was 0.58 mEq/L. Triamterene, 50 to 200 mg daily, normalized PK level in ten of the patients. The average increase in PK level was 0.72 mEq/L, which was not significantly different than that with potassium therapy. Some patients who responded to potassium did not respond to triamterene, and vice versa. Most of the administered potassium was excreted in the urine even with persisting hypokalemia. Addition of triamterene to diuretic therapy resulted in a small but statistically significant increase in plasma creatinine level.

Echocardiographic assessment by computer-assisted analysis of diastolic left ventricular function and hypertrophy in borderline or mild systemic hypertension

Systemic hypertension is a common cause of congestive heart failure. However, left ventricular (LV) systolic function remains normal for many years in patients with mild or moderate hypertension. In this study, high-quality M-mode echocardiograms were recorded in 7 patients with borderline hypertension, 14 patients with mild hypertension and 15 normal persons. Measures of systolic and diastolic LV function and the degree of LV hypertrophy were studied with the assistance of a tablet digitizer and dedicated microcomputer. Average blood pressure was 125 +/- 10/77 +/- 7 mm Hg in normal subjects, 146 +/- 18/92 +/- 2 mm Hg in patients with borderline hypertension and 150 +/- 11/102 +/- 4 in patients with mild hypertension. Indexes of systolic LV function were similar in all 3 groups. The peak rate of early relaxation of the LV posterior wall was significantly decreased in the group of patients with mild hypertension (4.7 vs 6.6 sec-1, p less than 0.01). The mitral valve closure rate was 150 +/- 32 mm/s in normal subjects, 119 +/- 35 mm/s in patients with borderline hypertension and 106 +/- 26 mm/s (p less than 0.001) in patients with mild hypertension. Mild LV hypertrophy was present in 6 of 7 patients with borderline and 13 of 14 patients with mild hypertension. The degree of hypertrophy and the level of blood pressure correlated poorly.(ABSTRACT TRUNCATED AT 250 WORDS)