Hypothyroidism in the elderly. When symptoms are not a 'normal' part of aging.

Clinical findings alone may not lead to prompt diagnosis of hypothyroidism in elderly patients. Therefore, routine thyroid function tests may be warranted in older patients, especially women. Serum thyrotropin (TSH) is the most sensitive marker for hypothyroidism, although the test is more costly than that for serum thyroxine (T4). Patients with overt hypothyroidism who have elevated TSH and low T4 levels require replacement therapy. In addition, patients who have a TSH level higher than 20 microU/mL or who have a mildly elevated TSH level and high titers of antithyroid antibodies may benefit from prophylactic treatment. The usual recommended replacement dose is 0.05 to 0.1 mg/day of levothyroxine sodium (Levothroid, Synthroid).

Effects of systole-specific pericardial pressure increases on coronary flow.

It has been postulated that intrathoracic pressure increases may impair cardiac function by decreasing coronary flow. To determine whether altered coronary flow causes or results from change in cardiac function, we used 14 anesthetized dogs in propranolol-induced heart failure following atrioventricular node ablation. After thoracoabdominal binding, the animals were paced and ventilated at the same frequency, and inspiration was synchronized with cardiac systole, resulting in systole-specific pericardial pressure increases (SSPPI). At SSPPI magnitudes of 15 and 30 mmHg, left atrial transmural pressure decreased and cardiac output increased, whereas decreases in left ventricular end-systolic transmural pressure and myocardial O2 consumption were directly related. Concurrent decreases in coronary sinus flow (CSF) and coronary arteriovenous O2 gradient with SSPPI 15 mmHg indicate autoregulation. However, the arteriovenous O2 gradient remained unaltered with SSPPI 30 mmHg, despite further decrease in CSF. Because the absolute diastolic aortic pressure decreased, a limit may exist for increasing SSPPI above which CSF may be directly affected.

Effect of left ventricular aneurysm on risk of sudden and nonsudden cardiac death.

Although left ventricular (LV) aneurysm is associated with increased mortality, its independent prognostic significance is controversial. To determine the effect of LV aneurysm on risk, 121 patients with healed myocardial infarction (MI), 55 manifesting akinesia on ventriculography (MI group) and 66 with LV aneurysm characterized by diastolic deformity (eccentricity) and systolic dyskinesia (LV aneurysm group) were studied. At a mean follow-up of 5.7 years, there were 32 cardiac deaths (12 MI vs 20 LV aneurysm), including 9 sudden deaths (1 MI vs 8 LV aneurysm). Multivariate analysis revealed decreasing ejection fraction to be the best predictor of total cardiac death, and revascularization to be protective. Nonsudden cardiac death was predicted by ejection fraction, absence of revascularization and right coronary artery disease, whereas sudden cardiac death was predicted by LV aneurysm and the frequency of ventricular ectopic complexes on Holter monitoring. In the MI group, ejection fraction was the only significant predictor of total cardiac death and nonsudden cardiac death. In the LV aneurysm group, total cardiac death, as well as nonsudden cardiac death, were predicted by ejection fraction, ventricular tachycardia and right coronary artery disease, whereas ventricular tachycardia predicted sudden cardiac death. It is concluded that the risk profile for total cardiac death differs between LV aneurysm and MI patients, and that LV aneurysm constitutes an independent predictor of late sudden cardiac death after MI. Moreover, on a substrate of LV aneurysm, the risk factors for sudden cardiac death and nonsudden cardiac death differ, with ventricular tachycardia being the sole predictor of sudden cardiac death. Furthermore, Holter monitoring is valuable in identifying patients at persistent risk of sudden cardiac death.