Hydrochlorothiazide and potassium chloride in comparison with hydrochlorothiazide and amiloride in the treatment of mild hypertension

A randomized, double-blind, cross-over study comparing 50 mg hydrochlorothiazide plus 5 mg amiloride (HCTZ/A) with 50 mg hydrochlorothiazide plus 26 mmol potassium chloride (HCTZ/K) was conducted in 18 patients with mild essential hypertension (diastolic pressure 90-105 mmHg). The sequence of treatment was: placebo for 2 weeks, one active drug for 3 weeks, placebo for 2 weeks, the other active drug for 3 weeks. The two agents were significantly and equally efficacious in lowering the systolic and diastolic blood pressure. Baseline vs. treatment mean serum potassium levels were 3.82 vs. 3.78 mmol/l for HCTZ/A and 3.82 vs. 3.70 mmol/l for HCTZ/K. The decrease in serum potassium level from baseline was significant for both agents but not significantly different when the two treatment forms were compared. Both treatment forms elevated fasting serum cholesterol and glucose. Serum triglycerides and uric acid rose significantly with HCTZ/K. Amiloride may affect the tubular handling of uric acid causing increased uric acid excretion, thus counteracting thiazide-induced hyperuricemia. During 3 weeks' extension of the main study, 5 patients received HCTZ/A in double the original dose (100 mg/10 mg) and 6 patients received HCTZ/K in double the original dose (100 mg/52 mmol). No further blood pressure reduction was observed on treatment with these doses. The mean serum potassium levels did not decrease further on doubling the HCTZ/A dose, while a significant fall was observed for HCTZ/K (3.60 vs. 3.42 mmol/l) (p less than 0.05, single tailed t-test). Both drug combinations were well tolerated and side-effects were not significantly different from those during placebo administration. This study demonstrates that 50 mg hydrochlorothiazide plus 26 mmol potassium chloride are as effective as 50 mg hydrochlorothiazide plus 5 mg amiloride, both in reducing blood pressure and preventing hypokalaemia in the treatment of essential hypertension. A small extension study indicates that amiloride might be more effective than potassium chloride in preventing hypokalaemia when high doses (100 mg/day) of hydrochlorothiazide are administered.     

Linkage of essential hypertension to chromosome 18q

We performed a genomewide scan with 904 microsatellite markers using 120 extended Icelandic families with 490 hypertensive patients. The families were identified by cross-matching a list of hypertensive patients from the Hypertension Clinic of the University Hospital (Landspitalinn) in Iceland with a genealogy database of the entire Icelandic nation. After adding 5 markers, we found linkage to chromosome 18q with an allele-sharing LOD score of 4.60 (P=2.1x 10(-6)). These results provide evidence for a novel susceptibility gene for essential hypertension on chromosome 18q and show that it is possible to study the genetics of essential hypertension without stratifying by subphenotypes.     

Support for involvement of the AHI1 locus in schizophrenia

Recently, markers in the Abelson Helper Integration Site 1 (AHI1) region were shown to be associated with schizophrenia in a family sample of Israeli-Arabs. Here, we report a study evaluating the relevance of the AHI1 region to schizophrenia in an Icelandic sample. Seven markers shown to confer risk in the previous report were typed in 608 patients diagnosed with broad schizophrenia and 1,504 controls. Odds ratios for the overtransmitted alleles in the Israeli-Arab families ranged from 1.15 to 1.29 in the Icelandic sample. After Bonferroni correction for the seven markers tested, two markers were significantly associated with schizophrenia. Thus, our results are in general agreement with the previous report, with the strongest association signal observed in a region upstream of the AHI1 gene.     

Retinal vessel oxygen saturation in healthy individuals

Purpose. We measured oxygen saturation in retinal vessels of healthy eyes to determine the effects of age, sex, and cardiovascular parameters, as well as the reliability of the measurements and topographic differences. Methods. The Oxymap T1 retinal oximeter is based on a fundus camera. It simultaneously captures retinal images at two different wavelengths and estimates retinal vessel oxygen saturation. Mean saturation of main retinal arterioles and venules was measured in 120 healthy individuals aged 18-80 years (median 47 years). Of the 120 participants 44 (37%) were male (49 years) and 76 (63%) female (44 years). Results. Oxygen saturation was 92.2 ± 3.7% (mean ± SD) in retinal arterioles and 55.6 ± 6.3% in venules. No significant difference in oxygen saturation was found between left and right eyes. The inferotemporal quadrant had lower oxygen saturation in arterioles and venules (P < 0.0001). Arteriolar oxygen saturation was stable with age. Venular oxygen saturation in males decreased by 1.9 ± 0.6% (mean ± SEM) per 10 years of age (P = 0.003) and by 0.7 ± 0.4% in females (P = 0.068). Arteriovenous (AV) difference increased by 1.5 ± 0.5% per 10 years in males (P = 0.004) and 1.0 ± 0.4% (P = 0.007) in females. For every 10 mm Hg increase in ocular perfusion pressure, oxygen saturation in arterioles increased by 0.9 ± 0.4% (P = 0.024) and in venules by 1.2 ± 0.7% (P = 0.075). Conclusions. Retinal arteriolar oxygen saturation is stable in healthy individuals, while there is a significant decrease in venular oxygen saturation with age in males and a similar trend in females. AV difference increases significantly with age for both sexes. Our study provided normative data for spectrophotometric retinal oximetry in the Caucasian population.     

Results of Attempted Cardiopulmonary Resuscitation of Patients Dying Suddenly outside the Hospital in Reykjavik and the Surrounding Area, 1976–1979

ABSTRACT. Cardiopulmonary resuscitation (CPR) was attempted in 222 cases of sudden death at the City Hospital, Reykjavik, during 1976–79. Of the 68 patients (31%) successfully resuscitated, 47 died in the hospital and 21 (9%) were discharged, 17 in good mental and physical condition. The mean combined response and transport time was 12.1 min and the ambulance mean time of response 7.3 min. The first ECG revealed considerable prognostic indications. Of the 90 patients who had ventricular fibrillation on admission, 42 (47%) were successfully resuscitated and 18 (20%) were subsequently discharged. Among 114 patients with asystole, resuscitation was successful in 23 (20%) and two (2%) were discharged. Immediate first aid in situ had a definite prognostic influence. These results compare favourably with those obtained elsewhere where the organization of first aid and emergency transport is similar. They do not, however, match the results achieved by fully specialized resuscitation teams trained to operate outside the hospital. Results of CPR of patients with cardiac arrest out of hospital in Reykjavik show increasing improvement over the years. This may be partly explained by a considerable public debate on this issue in 1978 and subsequent streamlining of activities.     

The use of echocardiography to measure isometric contraction time

The current methods for estimating isometric contraction time were discussed. Ultrasonically derived isometric contraction time, using external carotid pulse tracing, phonocardiogram, and the B-point of the mitral echogram was also measured. Recordings were performed in 10 normal subjects, and 15 patients. Hypertrophic cardiomyopathy (5), congestive cardiomyopathy (6), and ischemic heart disease (4). In 11 patients, the results were correlated with the internal isometric contraction time. The ultrasound isometric contraction time showed good correlation with the internal isometric contraction time (r = 0.92, P < 0.01).The external isometric contraction time showed less correlation with the internal isometric contraction time and was significantly shorter (P < 0.01). The ultrasound isometric contraction time showed a superior discriminating value to the external isometric contraction time for differentiating the normal subjects from the patients' group.     

Assessment of left ventricular function following coronary bypass surgery: a non-invasive study

Hardarson, T., Ziady, G. M., and Khattri, H. N. (1974).Thorax, 29, 359-365. Assessment of left ventricular function following coronary bypass surgery: a non-invasive study. In a series of 15 patients with ischaemic heart disease, systolic time intervals (STI) were measured before, and at one week, three months, and six months following coronary vein-graft surgery. Preoperatively, the left ventricular ejection time (LVET) was abnormally short in seven patients, while the pre-ejection period was abnormally long in seven patients, suggesting impaired left ventricular function. At one week after surgery LVET and total electromechanical systole (QA2) were significantly abbreviated. This may be explained by the transient fall in cardiac output or postoperative neurohumoral changes. For the group as a whole, no significant changes were found at three or six months, suggesting that cardiac function was generally preserved rather than improved. However, in individual patients changes in STI correlated with the clinical and angiographic estimate of success of the operative treatment.