Potassium Supplementation on BP in Patients with Essential Hypertension
A variety of diverse pieces of information suggest that potassium (K) status is related to blood pressure (BP). Dietary K intake correlates inversely with BP, and meta-analyses show significant BP reduction with supplementation.
Kawano and colleagues studied, in a randomized crossover design method, 55 hypertensive Japanese men and women given 2500 mg/d K supplementation divided in four doses for four weeks by office BP measurement, home self measurement, and 24-hour ambulatory measurement. Serum K, though not deviating from normal, increased from a mean of 4.15 to 4.42. Similarly, urinary potassium excretion increased from 54 to 96 mmol/d. All BP measurement techniques showed lower BP during K supplementation periods, to a highly statistically significant degree. Overall decreases in BP were modest: home BP decreased 3.6/1.6, 24 hr BP 3.4/1.2, and office BP 2.9/1.3. These changes were consistent whether the patient was receiving pharmacotherapeutic treatment and did not differ by class of antihypertensive agent.
Supplementation of K for hypertensive patients produces small but significant changes in BP.
Kawano Y, et al. Am J Hypertens 1998;11:1141-1146.
Clinical Scenario: The ECG shown in the figure was obtained from a 69-year-old man who was known to have complete left bundle branch block (LBBB). Is it possible to draw any other conclusions from evaluation of his ECG?
Interpretation: The rhythm is sinus at a rate of 80 beats/min. As noted above, the patient has complete LBBB. Despite opinion to the contrary, myocardial infarction can sometimes be diagnosed despite the presence of complete LBBB. Prior infarction is suggested in the above tracing by the presence of the wide and deep Q wave in lead aVL, late notching of the upslope of the S wave in two or more mid-precordial leads (in this case, leads V4 and V5), and primary ST-T wave changes (unexpected ST segment elevation in lead aVL, and the presence of an upright T wave in leads I and aVL). Q waves should not normally be present in lateral leads with typical LBBB. ST segments and T waves are normally directed opposite to the last QRS deflection in the three key leads (I, V1, V6) with typical bundle branch block. Thus, although one often will not be able to comment on the likelihood of past or present infarction in the setting of LBBB, the tracing shown here illustrates an example in which acute infarction should nevertheless be strongly suspected.
Suggested Reading
1. Hands ME, Cook EF, Stone PH. ECG diagnosis of myocardial infarction in the presence of complete LBBB. Am Heart J 1988;116:23-31.
2. Sgarbossa EB, et al for the GUSTO Investigators. ECG diagnosis of evolving acute myocardial infarction in the presence of LBBB. N Engl J Med 1996;334:481-487.
3. Grauer K. 12-Lead ECGs: A Pocket Brain’ for Easy Interpretation. Gainesville, FL: KG/EKG Press; 1998:23, 26.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content