Effect of quinapril or metoprolol on circadian sympathetic and parasympathetic modulation after acute myocardial infarction

Abnormal autonomic nervous system impairment in patients with acute myocardial infarction (AMI) has a circadian pattern with the greatest manifestation in the morning hours; it probably plays an important role in the pathogenesis of cardiac arrhythmias and acute ischemic syndromes. Angiotensin-converting enzyme inhibitors improve autonomic function in patients with AMI, but the circadian pattern of this effect has not been studied. Heart rate variability-normalized frequency domain indexes were assessed 5 days (baseline) after the onset of uncomplicated AMI and 30 days after therapy with quinapril (n = 30), metoprolol (n = 30), or placebo (n = 30) with a solid-state digital Holter monitor. Normal subjects (n = 30) were used as controls. Quinapril increased parasympathetic and decreased sympathetic modulation, and improved sympathovagal interactions manifested by an increase in normalized high-frequency power (HFP), and a decrease in normalized low-frequency power (LFP), and their ratio (LFP/HFP) during the entire 24-hour period (p<0.001), with maximal effect on the ratio (p<0.0001) between 02.00 to 04.00 A.M., 08.00 to 11.00 A.M., and 19.00 to 22.00 P.M. (delta% ratio -30%, -32%, and -26%, respectively). Metoprolol increased HFP and decreased LFP and the LFP/HFP ratio mainly between 08.00 A.M. to 12.00 noon, and 19.00 to 22.00 P.M. (delta% ratio -21%, and -12% respectively, p<0.001). Heart rate variability indexes in the placebo group and controls remained unchanged 30 days after the baseline study. In conclusion, quinapril increased parasympathetic, and decreased sympathetic and partially restored sympathovagal interaction in patients with uncomplicated AMI during the entire 24-hour period, with peak effect in the early and late morning and evening hours. Metoprolol had a similar effect during the late morning and evening hours, but at a lower level. These effects may prove beneficial in reducing cardiac arrhythmias and acute ischemic syndromes in past-AMI patients.     

Lipid lowering agents and the endothelium: an update after 4 years

Endothelial dysfunction represents an important step in the pathogenesis of atherosclerosis. All vascular risk factors can induce endothelial dysfunction, which in turn results in the loss of the protective effects of the endothelium culminating in the development of atherosclerosis. Dyslipidemia is a major vascular risk factor and is associated with endothelial dysfunction. Several studies showed that lipid-lowering agents exert beneficial effects on endothelial function in different populations at increased vascular risk, including patients without dyslipidemia. Therefore, other actions besides lipid-profile modification appear to be implicated in this benefit. However, it is unclear whether the improvement in endothelial function independently contributes to the vascular risk reduction during lipid-lowering treatment (e.g. with statins). It is also unclear whether the assessment of endothelial function would help identify patients who require more aggressive lipid-lowering treatment.     

Unusual manifestation of diarrhea-associated haemolytic uraemic syndrome in an adult

Hemolytic-Uremic Syndrome (HUS) is an uncommon disease characterized by microangiopathic hemolytica anaemia, thrombocytopenia, and acute renal failure. There are two forms of HUS: diarrhoea (D+)- and non-diarrhoea (D-)-associated HUS. We report the case of a 21-year-old woman presented to our department with jaundice, anaemia, thrombocytopenia, and anuria, preceded by a diarrheal prodrome, secondary to infection with Escherichia coli O157:H7. The whole clinical and laboratory investigation led to the diagnosis of HUS. Her condition was complicated with cholestasis, liver dysfunction, bleeding from the vagina, and myocardial involvement. She was treated only with fresh frozen plasma transfusions and hemodialysis, and despite the long duration of anuria (22 days), the patient showed subsequent improvement over days until full recovery one month later.