Phytoestrogen-Rich Diet in Postmenopausal Women
Phytoestrogens (pesgn) are compounds of plant origin that have weak estradiol-like estrogenic activity. The frequency of some cancers and symptom burden of menopausal hormone-withdrawal symptoms is somewhat different among populations that consume substantial amounts of PESGN. Typical food sources include soybeans, cereal bran, whole wheat, and legumes.
To assess the effect of such diets on menopausal parameters, 145 meno-pausal women were randomly assigned to either a PESGN-rich diet or control. The control group ate a regular omnivorous diet, and participants were instructed specifically to avoid soy products and flax seed (another high PESGN source).
For women who complied with the PESGN-rich diet, serum levels of PESGNs increased 100-fold (vs control group, no change). Four women were unable to tolerate soy-enriched diets. Nine women (2 in the PESGN group, 7 in the control) withdrew because menopausal symptoms remained intolerable. At 12 weeks, hot flashes and vaginal dryness scores were more significantly reduced in women on the PESGN diet when compared to the controls. Additionally, sex hormone binding globulin (SHBG) levels were increased only in the PESGN diet group. This increase in SHBG results in reduced levels of free estradiol and testosterone. Some authorities link decreases in free estradiol to decreased risk of breast cancer. The authors conclude that dietary PESGN augmentation may benefit symptomatic menopausal women.
Brzezinski A, et al. Menopause J North Am Menopause Soc 1997;4:89-94.
Clinical Scenario: The rhythm in the figure shows intermittent left bundle branch block (LBBB)or does it? How certain can you be of your diagnosis?
Interpretation: The underlying rhythm in the figure is sinusas identified by the first three beats in this tracing. These three complexes show a regular rhythm at 68 beats/min with upright P waves in this lead II monitoring lead. The QRS complex then changes in morphology beginning with the fourth beat. A P wave precedes this fourth beat (as indicated by the second arrow in the tracing)but the PR interval preceding the fourth beat is shorter than it is for the first three sinus beats. If the rhythm in this figure did represent sinus rhythm with intermittent bundle branch block, the PR interval preceding the fourth beat should not have changed.
As was the case for the ECG Review shown last month (see Intern Med Alert 1997;19:104), the key to interpreting the rhythm in this month’s review resides with recognizing that regular atrial activity continues throughout the rhythm strip. Setting your calipers to a P-P interval suggested by the distance between arrows allows you to "walk out" a fairly regular atrial rate on this tracing. As suggested by the third arrowsome P waves are hidden within various portions of the widened QRS complexes. Note in particular that a P wave notches the terminal part of the last widened complexbefore resuming normal sinus conduction for the last two beats on this tracing.
The fact that P waves continue at a fairly regular rate (of 65-70 beats/min) throughout this tracingand are unrelated to the widened QRS complexesestablishes the presence of transient AV dissociation. This strongly suggests that the widened (negatively directed) QRS complexes are likely to be ventricular in etiology. A ventricular origin for these four widened beats is solidified by the fact that the first beat in this run looks like a "cross" between the normally conducted sinus beats and the wider QRS complexes. This fourth beat is a fusion beat. Fusion beats reflect simultaneous (or near simultaneous) occurrence of supraventricular and ventricular impulses. Depolarization wavefronts are therefore initiated at almost the same time in both the atria and the ventricles. These depolarization wavefronts meet before they are able to complete their respective path. The ECG appearance of the resultant fusion beat therefore takes on characteristics of both the supraventricular and ventricular complex. Depending on whether the wavefronts meet high or low in the ventriclesthe fusion beat will take on more characteristics of the supraventricular complex or of the ventricular complex. For example, in the figure shown here, the fourth QRS complex looks less like the normally conducted sinus beats and more like the other negatively directed widened beats. Clinically, the significance of recognizing fusion beats is that it confirms widened complexes in a tracing are of ventricular etiology.
Note that the rate of the widened complexes in this figure is about 70 beats/min. This establishes that these four widened beats represent a short run of accelerated idioventricular rhythm (AIVR).
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