Biomedical subjects

J M Neutel

Publications and source records attributed to J M Neutel.

At least 73 records · Page 4Linked to original sources

PubMed1993

Coagulation and inhibitory and fibrinolytic proteins in essential hypertension.

Arterial hypertension (HTN) increases the risk of cerebral coronary, and other vascular complications that frequently involve platelet activation and blood coagulation. Several key proteins in the blood coagulation, fibrinolytic and inhibitory systems were studied in 29 men with HTN (aged 45 +/- 3 yr) and 15 normal men of the same age. Plasma levels of high-molecular-weight kininogen and factors XII, IX, VII, X, II, and XIII, as well as von Willebrand factor (vWF), fibrinogen, fibronectin, alpha 2-antiplasmin, tissue-plasminogen activator, D-dimer, platelet factor-4, and protein C were measured by the use of appropriate functional and immunologic assays before and after a cardiopulmonary exercise stress test. The concentrations of vWF, alpha 2-antiplasmin, and D-dimer were significantly (P < 0.02) higher in the HTN group as compared with the control group. The exercise stress test resulted in significant rises in the plasma vWF, alpha 2-antiplasmin, and tissue-plasminogen activator levels in the two groups. The concentrations of vWF and D-dimer were related to diastolic blood pressure (r = 0.44 and 0.40, respectively; P < 0.02). Levels of vWF also were related to left ventricular mass index and left ventricular posterior wall and septal thickness (r = 0.34, 0.43, and 0.34, respectively; P < 0.05). The constellation of these findings suggests a low-grade fibrin formation and degradation, the magnitude of which is related to the diastolic blood pressure. The observed abnormalities can potentially contribute to the cardiovascular complications of untreated HTN.

Adult↗

PubMed1992

Dependency of arterial compliance on circulating neuroendocrine and metabolic factors in normal subjects.

Reduced arterial compliance is now recognized as a feature of hypertension. Similarly, metabolic factors such as insulin, catecholamines and lipids are also associated with hypertension. This study explores the possibility that these neuroendocrine and metabolic factors may separately influence arterial compliance. Proximal compliance (aorta and large arteries) and distal compliance (small arteries and arterioles) were measured in 57 volunteers (30 hypertensive and 27 normotensive subjects, mean age 45 years). Compliance was quantified by analysis of arterial pulse wave contours obtained intraarterially together with hemodynamic estimates. Proximal compliance correlated with plasma insulin (r = -0.49; p less than 0.001), norepinephrine (r = -0.50; p less than 0.002), triglycerides (r = -0.39; p less than 0.01), total cholesterol (r = -0.33; p = 0.02) and high-density lipoprotein cholesterol (HDL) (r = 0.37; p less than 0.02). Similarly, distal compliance correlated with insulin (r = -0.37; p less than 0.02), triglycerides (r = -0.39; p less than 0.01), total cholesterol (r = -0.38; p less than 0.01) and HDL (r = 0.51, p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Impact of left ventricular hypertrophy on blood pressure responses to exercise.

It is claimed that exaggerated blood pressure (BP) responses to exercise are predictive of future hypertension and may also be indicative of left ventricular (LV) hypertrophy. The relation between LV hypertrophy and maximal exercise BP was examined in 35 normal male volunteers and 65 untreated hypertensive male patients. Multiple stepwise regression analysis revealed that preexercise systolic BP was the major determinant of maximal exercise systolic BP (r = 0.52; p less than or equal to 0.0001), indicating that higher baseline BP predicted higher exercise BP. However, hypertensive patients with LV hypertrophy had the smallest increases in systolic BP with exercise. Accordingly, there was an inverse relation between LV muscle mass and systolic BP responses to exercise in these patients (r = -0.34; p = 0.005). When compared with normotensive subjects, hypertensive patients had lower measures of maximal oxygen uptake and exercise heart rates (p = 0.01). This may indicate lower cardiac performance at maximal exercise and explain the reduced capacity of hypertensive patients with LV hypertrophy to increase systolic BP with exercise. Neither baseline nor exercise BPs correlated with LV mass; instead, the model of regression analysis indicated that body weight was the principal determinant of LV mass. Contrary to previous reports, exaggerated exercise BPs were not associated with LV hypertrophy in hypertensive or normotensive patients.

Adult↗

PubMed1992

Heredity and hypertension: impact on metabolic characteristics.

This study was performed to evaluate the possible role of heredity in the clinical characteristics of hypertension. Metabolic, endocrine, and renal measurements were compared in subjects with normal blood pressure who had a family history of hypertension (n = 60) with those of subjects with normal blood pressure who did not have a family history of hypertension (n = 48). The groups were matched for age (mean, 44 +/- 2 years and 45 +/- 2 years) and blood pressure (127 +/- 1/77 +/- 1 mm Hg and 127 +/- 2/77 +/- 1 mm Hg). The following parameters were higher in the patients with a family history of hypertension than in those without. Plasma insulin concentrations (14.1 +/- 1.1 vs 10.8 +/- 1.0 microU/ml; p less than 0.05), insulin-glucose ratio (0.15 +/- 0.01 vs 0.11 +/- 0.010; p less than 0.05), norepinephrine concentrations (315 +/- 24 pg/ml vs 208 +/- 20 pg/ml; p less than 0.01), plasma renin activity (2.1 +/- 0.2 ng Angl/ml/hr vs 1.6 +/- 0.2 ng Angl/ml/hr; p less than 0.02), total cholesterol levels (217 +/- 8 mg/dl vs 197 +/- 0.3 mg/dl; p less than 0.05), creatinine clearance (125 +/- 9 ml/min vs 96 +/- 8 ml/min; p less than 0.01), and albumin excretion rate (3.2 +/- 0.3 micrograms/min vs 2.6 +/- 0.3 micrograms/min; p = 0.1). Moreover, patients with a family history of hypertension had smaller increases in systolic blood pressure during treadmill exercise (55 +/- 3 mm Hg vs 64 +/- 3 mm Hg; p less than 0.03). There were no differences in echocardiographic left ventricular mass index between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Circulatory and extracirculatory effects of angiotensin-converting enzyme inhibition.

The antihypertensive effects of angiotensin-converting enzyme (ACE) inhibitors cannot be fully explained by their actions on the circulating renin-angiotensin system (RAS). Agents such as captopril or enalapril maintain efficacy during long-term therapy even when plasma concentrations of converting enzyme or angiotensin II are not fully suppressed. Components of the entire RAS exist at several sites, thereby making it possible for drugs to produce effects at extracirculatory locations. An ACE inhibitor such as quinapril that has a comparatively short plasma concentration half-life binds strongly to plasma ACE as well as to ACE in key tissues including artery wall, heart, and kidney. The effects of ACE inhibition on the tissue RAS are of potential importance in fully explaining the blood pressure-lowering effects of these drugs. ACE inhibitors might also reduce blood pressure by blocking nonhemodynamic actions of angiotensin II. They affect vascular properties by increasing compliance of arteries and they act on baroreceptors and central regulatory mechanisms. Furthermore, ACE inhibitors affect other neuroendocrine systems, including aldosterone, kinins, and prostaglandins; attenuation of sympathetic activity can contribute further to their antihypertensive properties. Actions independent of circulating renin effects do not necessarily require plasma ACE inhibition throughout a 24-hour period. Sustained antihypertensive effects by drugs with short durations of plasma ACE inhibition give credibility to therapeutic targets beyond the circulating RAS.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1991

Cardiovascular and metabolic characteristics of hypertension.

Hypertension is now seen as a broader condition than high blood pressure alone. Large-scale epidemiologic studies have established that high blood pressure is associated with an increased risk of cardiovascular events, but clinical trials of antihypertensive therapy have shown an inconsistent reduction in major cardiovascular endpoints. Importantly, the incidence of coronary disease has been reduced to only a small extent, suggesting that factors beyond high blood pressure are important in the genesis of atherosclerotic disease in hypertensive patients. It is evident, for example, that patients with hypertension have an exaggerated vulnerability to the consequences of lipid abnormalities. Moreover, it has recently been established that hypertension is characterized by insulin resistance and altered glucose tolerance. As a result, high plasma concentrations of insulin produce proliferative effects on vascular smooth muscle and connective tissue, and they may adversely affect the lipid profile. The left ventricle is also involved in hypertension--independent of blood pressure. There is growing evidence that there are increases in the muscle mass of the left ventricle and changes in its diastolic filling characteristics at the very early stages of hypertension. The arterial circulation is similarly involved, for alterations in structure or function, reflected by diminished arterial compliance, can be demonstrated prior to the appearance of clinical hypertension. Treatment designed to protect hypertensive patients from cardiovascular events must not only be based on blood pressure, but must take into account all the components of the hypertension syndrome.

Blood Glucose↗

PubMed1991

Left ventricular diastolic filling alterations in normotensive young adults with a family history of systemic hypertension.

To characterize the cardiovascular consequences of a history of hypertension in first-degree relatives in normotensive young adults, 72 normotensive (diastolic blood pressure [BP] less than 90 mm Hg) healthy volunteers (age 18 to 30 years) were studied with 2 dimensionally guided M-mode echocardiography, pulsed Doppler echocardiography, and 2-hour automated BP monitoring. Of the 72 subjects, 19 (12 men and 7 women) had a family history of hypertension and were compared with 19 subjects without a family history of hypertension who were matched for systolic BP and gender. There were no detectable differences in 2-hour average BP, left ventricular (LV) mass or wall thickness, or echocardiographic systolic functional indexes between subjects with and without a family history of hypertension. Doppler-derived diastolic functional indexes demonstrated more prominent late diastolic filling in subjects with a family history of hypertension. Late diastolic transmitral flow time and flow velocity integral were greater (132 +/- 24 vs 117 +/- 17 ms, p less than 0.05; and 2.5 +/- 0.7 vs 1.9 +/- 0.5 cm, p less than 0.01, respectively). To measure possible gender-related effects of a family history of hypertension, the men and women were analyzed separately. The 12 men with a family history of hypertension had greater peak late (40 +/- 0.9 vs 31 +/- 0.8 cm/s, p less than 0.02) and ratio of late-to-early (0.64 +/- 0.19 vs 0.46 +/- 0.10, p less than 0.01) transmitral flow velocities and greater late transmitral flow velocity integrals (2.6 +/- 0.8 vs 1.9 +/- 0.5 cm, p less than 0.05) than the matched male control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

A comparative study of atenolol, nifedipine and their combination in the treatment of hypertension.

The antihypertensive effects, as assessed by clinical and ambulatory blood pressure measurement, of nifedipine slow-release (SR), atenolol and the two in combination were evaluated in 28 known hypertensives in a placebo-controlled, double-blind, randomised cross-over trial. Clinical blood pressure was significantly lower on combination therapy (P less than 0.025) than on either agent alone, although all therapeutic agents reduced blood pressure significantly when compared with placebo (P less than 0.01). All ambulatory blood pressure measurements obtained on any therapeutic agent were significantly lower than those obtained on placebo (P less than 0.01). The mean daytime (08h00-17h00) ambulatory blood pressure measurement as well as the percentage of this monitoring period during which patients were hypertensive were significantly lower (P less than 0.01) on combination therapy than on nifedipine SR. A similar pattern was observed for 24-hour ambulatory blood pressure measurements. Headache was the most significant adverse effect. This was most common with nifedipine SR, less common with combination therapy and least common with atenolol. Combination therapy with nifedipine SR and atenolol is therefore a viable therapeutic alternative in the treatment of patients with benign essential hypertension.

Adult↗

PubMed1991

Immediate blood pressure effects of the renin inhibitor enalkiren and the angiotensin-converting enzyme inhibitor enalaprilat.

The antihypertensive effects of the renin inhibitor enalkiren were compared with those of the angiotensin-converting enzyme inhibitor enalaprilat in 17 hypertensive patients (14 white, 3 black; mean age 57 years), whose renin systems had been stimulated by diuretic pretreatment. Patients were studied on 3 separate in-hospital days. On the first study day patients received placebo alone. On day 2 they received intravenous bolus doses of enalkiren (0.03 to 1.0 mg/kg), and on day 3, intravenous bolus doses of enalaprilat (0.625 to 1.25 mg). Each agent reduced systolic (p less than 0.01) and diastolic (p less than 0.01) blood pressure (BP) from baseline levels. The acute decrease in systolic BP of 18.5 +/- 0.4 mm Hg during enalkiren tended to be greater (p less than 0.01) than the decrease of 12.6 +/- 0.7 mm Hg during enalaprilat. Decreases in diastolic BP during enalkiren (11.9 +/- 0.4 mm Hg) were also slightly greater (p less than 0.1) than those during enalaprilat (9.2 +/- 0.4 mm Hg). Based on prestudy plasma renin activity (PRA), patients were divided into "high" renin (PRA greater than 3.5 ng angiotensin l/ml/hr; n = 6) and "low/normal" renin (less than 3.5 ng angiotensin l/ml/hr; n = 11) groups. Reductions in diastolic BP in the "high" renin group during enalkiren (30 +/- 5/20 +/- 3 mm Hg) tended to be greater (p less than 0.07) than those during enalaprilat (23 +/- 7/14 +/- 1 mm Hg); differences were not significant in the "low/normal" group (12 +/- 2/7 +/- 2 and 7 +/- 2/8 +/- 1 mm Hg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Effects of angiotensin II on pressor responses to norepinephrine in humans.

In previous studies in the conscious rabbit and in isolated artery preparations, low doses of angiotensin II synergistically amplified the pressor effects of the sympathetic neurotransmitter, norepinephrine (NE). To determine whether these observations could be replicated in humans, 9 normal adult male volunteers (mean age: 34) each were given 3 i.v. doses of NE (25, 50 and 100 micrograms.kg-1.min-1) during consecutive 10 min infusion periods. On a second study day, the procedure was repeated during infusion of angiotensin II in a subpressor dose (1.25 ng.kg-1.min-1). The angiotensin II didn't alter the BP responses to NE, but it attenuated the heart rate (HR) decreases associated with the NE infusions by 80% (P less than 0.05), 42% (P less than 0.05) and 42% (P less than 0.1). The two study days were then repeated following 2 weeks of oral treatment with the angiotensin converting enzyme inhibitor captopril (which, despite significantly decreasing baseline BP, also tended to decrease HR). In the presence of captopril, the pressor responses to the NE challenges were reduced by 50% (P less than 0.05), 33% (P less than 0.05) and 13% (P less than 0.1) compared with the pre-captopril responses. Thus, angiotensin II in subpressor doses appears to enhance NE pressor effects by attenuating the compensatory HR responses, whereas inhibition of endogenous angiotensin II mechanisms weakens the BP-raising actions of NE. These findings in humans are consistent with earlier observations that the renin-angiotensin system can directly amplify sympathetic pressor effects in two separate ways: by modifying baroreceptor sensitivity and by enhancing the actions of norepinephrine on vascular smooth muscle.

Administration, Oral↗

PubMed1991

Arterial properties of early hypertension.

In addition to high blood pressure, hypertension is characterised by metabolic and cardiovascular abnormalities, including decreased arterial compliance. To evaluate arterial involvement in early hypertension, we have employed a technique that analyses the arterial pulse wave contour to separately quantify proximal compliance (aorta and large arteries) and distal compliance (small arteries and arterioles). Proximal compliance was 24% lower in patients with borderline (diastolic BP 90-99 mmHg, n = 22) and 33% lower in patients with established (n = 19) hypertension than in normals (n = 15); distal compliance was 58% and 61% lower. These differences were not age-dependent, for in 27 age-matched pairs, proximal and distal compliances were 22% (P less than 0.01) and 55% (P less than 0.01) lower in hypertensives (diastolic BP greater than or equal to 95 mmHg) than in normotensives. Moreover, independent of BP or age, both proximal (P less than 0.05) and distal (P less than 0.01) compliance values were significantly lower in subjects with a family history of hypertension than in those without. Proximal compliance correlated inversely with indices of BP variability and heart work measured by automated whole-day blood pressure monitoring. Thus, changes in the elastic properties of the distal arterial circulation, reflected by decreased compliance, occur at the initiation of hypertension and may be an early diagnostic marker. Low proximal compliance appears to be associated with established hypertension, and might be a determinant of cardiovascular prognosis.

Adult↗

PubMed1991

Applications of ambulatory blood pressure monitoring in clinical practice.

Traditionally, blood pressure has been measured by the sphygmomanometer in the medical office. There is growing evidence, however, that office blood pressures may not be typical of values throughout the day. Between 20% and 30% of patients diagnosed with hypertension in the office actually are normotensive at other times. Ambulatory blood pressure monitoring with small, portable devices that automatically measure blood pressure every few minutes throughout the day appears to be an appropriate tool when "white-coat" hypertension is suspected--i.e., for individuals whose hypertension in the physician's office is not associated with other physical or historical evidence for cardiovascular disease or with other risk factors. Used prudently, ambulatory monitoring is a cost-effective technique that potentially can prevent unnecessary treatment of patients. Moreover, whole-day measurements may correlate more closely than office measurements may correlate more closely than office measurements do with findings of cardiovascular disease. This new approach also has highlighted the circadian pattern of blood pressure, especially the sharp early to mid-morning increase that coincides with an increased tendency to major cardiovascular events. This has focused attention on directing antihypertensive therapy towards the morning hours. Ambulatory monitoring is now used routinely in studies of antihypertensive drugs. This technique has no placebo effect and takes fewer patients to assess drug efficacy than do conventional methods.

Antihypertensive Agents↗

PubMed1990

Evaluation of the post-exercise time-course behaviour of ST-segment and T-wave changes in the elimination of the false-positive stress ECG.

Routine stress ECG has been criticised for yielding too many so-called false-positive results because ST-segment and T-wave (ST/T) changes that develop during and after exercise are prevalent. Recent studies in our institutions indicate that the time-course behaviour patterns of ST/T configurational abnormalities after exercise reflecting myocardial ischaemia are different from those that do not. The epicardial coronary arteries of 111 patients, who had positive stress tests for ischaemia based on ST/T configurational changes alone but were considered non-ischaemic when the ST/T time-course behaviour was analysed, were assessed. Of these patients, 102 had normal coronary arteries, 7 had insignificant stenoses and only 2 had significant coronary artery diseases. ST/T abnormalities on stress testing with a non-ischaemic time-course pattern should be regarded in the same category as ST segments that remain normal as far as the detection of myocardial ischaemia due to epicardial coronary artery disease is concerned. This policy has resulted in an improved predictive value of exercise testing and has considerably decreased the number of patients subjected to coronary arteriography in our institutions. The assessment of the post-exercise stress ECG remains the most practical and cost-effective method for detecting ischaemic heart disease.

Adolescent↗

PubMed1990

Bezafibrate and simvastatin (MK-733) in the treatment of primary hypercholesterolaemia.

Simvastatin, a new 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitor, was compared to bezafibrate, a fibric acid derivative, in an open cross-over placebo-controlled study. Bezafibrate was administered as a 200 mg dose 3 times daily, while simvastatin dosage ranged from 10 mg to 40 mg once daily at night. Bezafibrate produced a non-significant 13.1% (P = 0.113) decrease in total cholesterol (TC), a 20.7% (P less than 0.05) decrease in low-density lipoprotein cholesterol (LDL-C), an increase of 26.5% (P less than 0.01) in high-density lipoprotein cholesterol (HDL-C) and an improvement in the HDL:LDL ratio of 77.3% (P less than 0.01). Simvastatin 10 mg and 20 mg daily reduced TC by 18.6% and 22.6%, respectively, and LDL-C by 23.9% and 28.6% respectively (P less than 0.01), while no significant increase was noted in HDL-C. Simvastatin 40 mg daily reduced TC and LDL-C by 27.1% and 37.6%, respectively (P less than 0.01), increased HDL-C by 32.0% (P less than 0.05) and improved on the HDL:LDL ratio by 130.8% (P less than 0.01). This showed improvements over bezafibrate of 13.5% for TC, 18.9% for LDL-C, 6.0% for HDL-C and 55.8% for HDL:LDL ratio. It was concluded that simvastatin was well tolerated and had significant hypocholesterolaemic effects when taken once daily.

Adult↗

PubMed1990

Antihypertensive effects of beta-blockers administered once daily: 24-hour measurements.

Whole-day automated ambulatory blood pressure (BP) monitoring was used to assess the duration of the antihypertensive actions of the beta-blockers atenolol (50 to 100 mg; n = 20) and acebutolol (400 to 800 mg; n = 19) each given once daily at 9 AM. When compared with its pretreatment 24-hour average, atenolol decreased diastolic BP by 10 +/- 2 mm Hg (p less than 0.01) and systolic BP by 12 +/- 2 mm Hg (p less than 0.01). Acebutolol decreased the 24-hour diastolic BP by 11 +/- 1 mm Hg (p less than 0.01) and systolic BP by 13 +/- 2 mm Hg (p less than 0.01). More specifically, a comparison of the two drugs during the final 6 hours (3 AM to 9 AM) of the dosing interval showed that the mean decrease in diastolic BP of 10.2 +/- 1.5 mm Hg with acebutolol was greater (p less than 0.05) than the decrease of 6.2 +/- 1.3 mm Hg with atenolol. Moreover, this final 6-hour effect of atenolol was less (p less than 0.01) than that observed during the first 18 hours of the day. The late effects of acebutolol did not change significantly from its early effects. The two agents also differed in their trough (final 2-hour decrease in diastolic BP) and peak (maximum 2-hour decrease in diastolic BP) effects: for atenolol the peak-to-trough difference was 7.8 +/- 3.1 mm Hg (p less than 0.05), whereas for acebutolol it was 3.8 +/- 4.2 mm Hg (N.S.). This study confirms the efficacy of atenolol and acebutolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol↗

PubMed1990

Acute pharmacokinetic and hemodynamic effects of intravenous bolus dosing of nicardipine.

The antihypertensive effects, duration of action, and pharmacokinetics of intravenous bolus doses of nicardipine were investigated in a series of patients with mild-to-moderate hypertension. Patients with a supine diastolic blood pressure between 95 and 114 mm Hg and a heart rate less than 90 beats/min who received no other antihypertensive medications were included in the study. On separate study days, single intravenous bolus doses of 0.125, 0.25, 0.5, 1, 3, 5, and 7 mg of nicardipine were administered over a 2-minute period. Blood pressure and heart rate were measured for 6 hours after an intravenous bolus of nicardipine was given, and serum nicardipine levels were measured throughout the study. Although the antihypertensive effect occurred immediately during the bolus infusion, peak average decreases in systolic and diastolic pressure ranged from 20 to 25 and 15 to 44 mm Hg, respectively, and occurred 2.5 +/- 0.6 minutes after infusion. Heart rate increased by 12 to 40 beats/min during the peak effect. The mean duration of action after an intravenous bolus dose was 24 +/- 5 minutes. A dose-response relationship was observed, as both nicardipine dosage and plasma nicardipine concentration correlated with reduction in blood pressure. These data indicate that bolus administration of nicardipine may provide a practical approach for the rapid parenteral treatment of hypertensive states.

Blood Pressure↗

PubMed1990

Assessment of renin dependency of hypertension with a dipeptide renin inhibitor.

To evaluate the participation of the renin-angiotensin system in sustaining hypertension, we administered the specific dipeptide renin inhibitor enalkiren (A-64662) to 18 patients with essential hypertension. Ascending intravenous bolus doses (0.03, 0.1, 0.3, and 1.0 mg/kg) of the inhibitor were each given at 45-minute intervals to patients maintained on an ad libitum sodium diet who were studied while in bed in the semirecumbent posture. Enalkiren produced marked decreases in plasma renin activity (PRA) that were still evident 8 hours after completion of dosing. Systolic and diastolic blood pressures were decreased in a dose-dependent fashion without an effect on heart rate. Repetition of this procedure after patients were subjected to sodium depletion by 1 week of thiazide treatment produced amplified decreases in blood pressure. Despite the short plasma half-life of the inhibitor, these blood pressure-lowering effects were sustained for 4-8 hours when compared with parallel placebo administration in the same patients. Both the baseline PRA and the inhibitor-induced changes in PRA correlated significantly with blood pressure changes during the unstimulated and the sodium-depleted studies. However, effects of the inhibitor on diastolic blood pressure in the latter study correlated most closely with actual increases in renin produced by diuretic pretreatment. Thus, this specific renin inhibitor has demonstrated the dependency of blood pressure on the renin-angiotensin system even during basal conditions in hypertensive patients. Moreover, renin response to sodium depletion appears to be an attribute that additionally characterizes individual hypertensive patients.

Adult↗

PubMed1990

The aeromedical implications of atrial fibrillation.

A retrospective study was undertaken to determine the incidence of spontaneous atrial fibrillation (AF) in a group of asymptomatic pilots. The electrocardiograms of 13,037 aircrew members accumulated between 1964 and 1986 were reviewed and those coded for AF were extracted. In each case an attempt was made to investigate factors relating to the onset, course, and prognosis of the AF. Eight subjects (mean age 50.1 years) were found to have AF. Of this group, two had a single isolated episode of AF for which a specific precipitating factor was implicated, three had recurrent paroxysmal AF of which one progressed to chronic persistent AF, and three had chronic persistent AF from the outset. The mean follow-up period for the eight subjects was 13.6 years. The two pilots who had isolated attacks of AF have thus far had no subsequent episodes of AF. Five of the remaining six have been completely well, while one required treatment for an embolus to his left leg. Concerning the aeromedical implications, we believe that pilots demonstrating single isolated episodes of AF in the presence of a normal heart, and in whom recovery is complete, should be allowed to return to full aviation duties on a waiver clause. Patients with chronic AF, lone AF, or paroxysmal AF should be excluded from all flying duties.

Adult↗