Body Weight and Hypertension
Body Weight and Hypertension
Cross-sectional studies demonstrate an association between obesity and hypertension (HTN), and prospective studies indicate that obesity is a predictive factor for future development of HTN. Short-term (6 months or less) and intermediate term (6-12 month) studies of weight loss demonstrate favorable changes in blood pressure with weight reduction. Whether weight reduction in populations normotensive at baseline will prevent or delay onset of HTN is inadequately defined.
Using BMI at age 18 and midlife, as well as weight changes, the authors examined data on 121,700 nurses in the Nurses Health study, begun in 1976, only including women who were free of hypertension, manifestations of cardiovascular disease, or cancer at baseline.
For every 1 kg/m2 increase in BMI, there was a 12% increased risk for HTN. In normotensive women, reduction of weight by 5-9.9 kg was associated with a 15% reduced likelihood of developing HTN; greater than 10 kg weight loss reduced likelihood of HTN development by 26%. Among normotensive women who gained weight, every 1 kg increase in body weight increased risk for HTN by 5%. Maintenance of weight levels as close as feasible to ideal body weight reduces the risk of subsequent development of HTN.
Huang Z, et al. Ann Intern Med 1998; 128:81-88.
Clinical Scenario: The ECG in the figure was obtained as part of a pre-employment physical exam. The patient was n otherwise healthy and completely asymptomatic 22-year-old man who was applying for a position as a policeman. How would you interpret this tracing? Would you "clear" the patient for work? Physical exam (including cardiac auscultation) was completely normal.
Interpretation: The rhythm is sinus arrhythmia. All intervals are normal. The mean QRS axis is +80°. Although QRS amplitude appears to be increased, assessment for left ventricular hypertrophy (LVH) is difficult in view of the patient's age. Increased QRS amplitude is often seen in young adults and does not necessarily reflect LVH.
The most remarkable finding on the tracing is the presence of surprisingly deep Q waves in multiple leads. Normally, small narrow q waves may be seen in lateral leads. Such q waves are commonly referred to as "normal septal q waves"-since they reflect the normal process of septal depolarization. Thus, because the septum normally depolarizes from left to right-one or more left-sided leads (i.e., leads I, aVL, V4, V5, and V6) commonly manifest a small initial negative deflection or q wave. On occasion, septal q waves may also be seen in the inferior leads. This is most likely to occur when the mean QRS axis is relatively vertical-as it is in this case.
The unusual finding in the ECG shown in the figure is not that Q waves are present in so many leads, but that these Q waves are relatively deep-and clearly much deeper than is usually seen with "normal" septal q waves. This may reflect a relative prominence of septal forces. In support of the suggestion that septal forces are greater than usual is the finding of a surprisingly tall initial R wave in lead V1.
The purpose of pre-employment screening is to hopefully identify persons who might be placed at undue risk if accepted for the job they for which they are applying. Although far from perfect as a screening tool, an ECG is often obtained as a means to assess cardiovascular risk. The ECG in the figure should not be interpreted as normal for a 22-year-old man.
Sudden cardiac death is a rare event among otherwise healthy adolescents and young adults. In this age group, almost all episodes of this tragic occurrence are associated with underlying congenital cardiac abnormalities-the most common of which is hypertrophic cardiomyopathy (HCM). HCM is characterized by marked ventricular hypertrophy with disproportionate enlargement of the ventricular septum. Obstruction of the left ventricular outflow tract may occur with cardiac contraction. Although a heart murmur suggesting this lesion will usually be heard on cardiac auscultation, this is not always the case.
The ECG is typically abnormal in patients with HCM. However, ECG findings are variable and generally nonspecific (i.e., increased QRS amplitude, ST-T wave flattening or depression, bundle branch block, etc.). One finding that should heighten suspicion for the possibility of HCM is prominence of septal forces-as shown in this figure. Further evaluation with echocardiography is clearly indicated for such cases. Surprisingly, the patient in this case turned out to have a dilated (not hypertrophic) cardiomyopathy. Strenuous work was therefore not advised.
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