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Blood pressure and heart period variability have been measured directly in 142 subjects with mild hypertension over 24 h. The variabilities have been expressed as the standard deviation of 2 min averages of all beats over 24 h. Baroreflex sensitivity was assessed in 102 subjects by the phenylephrine method. Blood pressure varies over a range of approximately 40% around the mean by day and by approximately 20% at night. The variability of blood pressure by day was inversely proportional to the sensitivity of the baroreflex (r = -0.33, P less than .001), while the variability of heart period was directly related to the sensitivity of the reflex (r = 0.27, P less than .01). Neither of these relationships was significant at night. An inverse relationship between heart period and blood pressure was shown by regression analysis of blood pressure and heart period averages over 24 h. The steepness of the slope of the heart period-systolic blood pressure relationship was strongly correlated with the baroreflex sensitivity (r = -0.55, P less than .001), suggesting that blood pressure variations are substantially buffered by changes in heart frequency. Thus, a more stable heart rate that results from an ineffective baroreflex is associated with a more variable systolic blood pressure.

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We report a case of polymorphous ventricular tachycardia caused by treatment with the post-synaptic alpha-blocking agent indoramin. This has not been reported with indoramin previously, nor to our knowledge with any other alpha-blocker. This pro-arrhythmic effect appears to be related to its class 3 anti-arrhythmic properties (QT interval prolongation) which is dose dependent, occurring only at large doses.

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Ten patients underwent myocardial scintigraphy with 123I-iodo-heptadecanoic acid (HDA), which was injected in the last minute of maximal exercise testing. Six of the patients were rescanned following percutaneous transluminal coronary angioplasty. All ten patients underwent full coronary angiography. There were visible perfusion defects on the static images in 74% of the myocardial areas which were supplied by an artery with a stenosis greater than 75%. The mean half life recorded from areas distal to an arterial stenosis of at least 90% (35.69 min +/- 41.25 min), was longer than the expected normal mean (18.85 min +/- 3.35 min). However, the difference was not statistically significant. The static images changed in some patients following angioplasty, however there was no consistent alteration in the half lives. It was concluded that HDA is a suitable agent for investigating myocardial perfusion, but that the half life cannot be measured adequately for clinical purposes with a planar imaging system.

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Combined amiodarone and disopyramide therapy is generally believed to be potentially harmful. We report 11 patients who have received this combination, none of whom have experienced any serious adverse reactions. In addition, 9 of the 11 patients derived marked clinical benefit. This combination deserves further evaluation as an anti-arrhythmia therapy.

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To determine whether venous plasma norepinephrine concentrations consistently reflect changes in sympathetic nervous activity, the influence of mental arithmetic, static handgrip, and submaximal bicycle exercise on intra-arterial blood pressure, heart rate, and plasma norepinephrine was studied in 51 subjects with untreated essential hypertension (mean age, 46 years; range, 16-69 years). At rest, plasma norepinephrine was unrelated to age or blood pressure. Mental arithmetic increased mean arterial pressure from 108 +/- 18 to 127 +/- 18 mm Hg (mean +/- S.D.; p less than 0.001) and heart rate from 69 +/- 7 to 93 +/- 13 beats/min (p less than 0.001) but not plasma norepinephrine (547 +/- 297 to 518 +/- 250 pg/ml). Isometric exercise raised mean arterial pressure from 115 +/- 18 to 148 +/- 21 mm Hg (p less than 0.001) and heart rate from 76 +/- 9 to 95 +/- 13 beats/min (p less than 0.001) but not plasma norepinephrine (683 +/- 253 to 741 +/- 253 pg/ml). Bicycle exercise increased mean arterial pressure from 114 +/- 20 to 146 +/- 26 mm Hg (p less than 0.001), heart rate from 77 +/- 9 to 128 +/- 19 beats/min (p less than 0.001), and plasma norepinephrine from 645 +/- 228 to 1151 +/- 462 pg/ml (p less than 0.001). Both the maximum mean arterial pressure and the peak heart rate attained during bicycle exercise were related to the exercise plasma norepinephrine level (r = 0.33, p less than 0.02 and r = 0.28, p less than 0.03, respectively). Increases in plasma norepinephrine with exercise were not greater in older or more hypertensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

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Six subjects were investigated to establish whether self-recorded morning blood pressure is a reliable indicator of that taken throughout the day. After instruction, subjects recorded resting blood pressure on 6 successive mornings, and then hourly throughout the day. The morning pressures in each patient on each of the 6 days were very closely related to one another, with an overall mean of 157/102 mmHg (n = 36). Overall blood pressures throughout the day were not significantly different from the morning ones (158/100 mmHg, n = 88). Standard deviation for morning systolic blood pressure in each patient ranged from 4.5-8.4 compared with 3.8-10.4 mmHg for systolic blood pressure throughout the day. For diastolic blood pressure the ranges of standard deviation were 2.3-8.4 and 2.6-6.5 mmHg, respectively. No patient demonstrated a circadian rhythm. It seems that self-monitoring of blood pressure is reproducible and that the time of day that the measurement is made is unimportant, provided the patient is resting.

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Blood pressure variability throughout the day has been found to be inversely related to baroreflex sensitivity, as is the response to injected phenylephrine, mental stress and sleep. It is concluded that variability in blood pressure results in some degree from defective buffering of blood pressure by the baroreceptors.

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Blood pressure variability has been studied from 24-h direct arterial pressure recordings in 109 subjects (36 normals and 73 hypertensives). Baroreflex sensitivity was also measured. From the 24-h record a linear relationship was found between systolic pressure and heart period. The slope was related to baroreflex sensitivity (r = 0.66, P less than 0.001). Those with shallow slopes had a high systolic pressure level and greater variability, thus efficient control of heart rate limits blood pressure variability.

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