To evaluate if QT dispersion (QTd) may be affected by the number of obstructed coronary arteries (CAs) in patients with acute myocardial infarction (MI) and undergoing angioplasty, and to evaluate if QTd may be affected by ejection function of the heart. The infarct related CA was identified by coronary angiography in 141 patients (97 men, mean age 61.6 +/- 12.9 years) with acute MI undergoing percutaneous angioplasty. Successful reperfusion was defined as TIMI III flow with < 20% residual stenosis. QTd, calculated by subtracting the shortest from the longest QT interval on 12-lead electrocardiograms, was examined immediately before and after angioplasty, at 24 hours, and 3 days after angioplasty. Successful reperfusion was achieved in 98 (69.5%) patients. Prolonged QTd at baseline was found in all patients with ischemia. A trend toward a decrease in QTd was observed immediately after angioplasty and at 24 hours, and a significant decrease at 3 days in patients with successful reperfusion regardless of the number of occluded CAs. There was no change in QTd found in patients with no reperfusion. An increase in QTd was observed in patients with acute ischemia due to single or multivessel disease.

Angioplasty, Balloon, Coronary↗

PubMed2003

Hemodynamic and electrocardiographic effects of short-term Ginkgo biloba.

OBJECTIVE: To evaluate the immediate and short-term hemodynamic and electrocardiographic effects of Ginkgo biloba (ginkgo). METHODS: Healthy volunteers were randomized to receive ginkgo 120 mg or placebo twice daily for 7 days in this prospective, double blind trial. After at least a 7-day washout period, subjects were crossed over to an additional 7 days of alternate therapy. Blood pressure, heart rate, and 12-lead electrocardiograms were evaluated immediately before (baseline), and at 1, 3, and 5 hours after observed ingestion of study drug on days 1 and 7 of therapy. Electrocardiographic parameters (P wave and QRS complex duration; PR, QT, and QTc intervals) were measured in lead II by a blinded investigator. RESULTS: Ginkgo had no effect on any of the evaluated electrocardiographic parameters at any time point on days 1 or 7. Additionally, no changes in heart rate or systolic and diastolic blood pressure were found between the groups at any time point on any evaluative day. CONCLUSIONS: Commonly used doses of Ginkgo biloba do not have any immediate or short-term effects on blood pressure, heart rate, or electrocardiographic variables in young, healthy volunteers.

Adult↗

PubMed2003

Effects of intravenous magnesium sulfate on the QT interval in patients receiving ibutilide.

STUDY OBJECTIVE: To determine the effect of intravenous magnesium sulfate on the QT and QTc intervals in patients receiving ibutilide for immediate chemical cardioversion of atrial flutter or fibrillation. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: Hospital cardiology unit. PATIENTS: Twenty patients (mean age 72 +/- 14 yrs) with atrial fibrillation (12 patients) or atrial flutter (8 patients) who were scheduled to receive ibutilide. INTERVENTION: After determining that the patients' baseline QTc intervals were less than 440 msec and baseline serum magnesium levels were within normal limits (mean 2.1 +/- 0.29 mg/dl), the patients were randomly assigned to receive either a 10-minute infusion of magnesium sulfate 2 g in 50 ml of 0.9% sodium chloride or placebo immediately before ibutilide therapy. An additional 2 g of intravenous magnesium sulfate or placebo was given over 1 hour, 10 minutes after the first dose of ibutilide. MEASUREMENTS AND MAIN RESULTS: QT interval duration was measured manually in all 12 leads by using a 0.5-mm-scale precision ruler and magnifying lens. The QT interval increased 29% from baseline at 30 minutes after ibutilide therapy in the placebo group (p=0.007), but no significant change from baseline occurred in the magnesium sulfate group. The 30-minute QTc interval in the placebo group was 18% higher than the baseline value (p=0.01) but did not change significantly in the magnesium sulfate group. QTc changes from baseline were greater in the placebo group than in the magnesium sulfate group at 30 minutes (75 vs 19 msec, respectively, p=0.04). Magnesium sulfate reduced the risk of an ibutilide-induced QTc interval increase of greater than 30 msec or greater than 60 msec and reduced the risk of a QTc interval value of more than 500 msec by 65%, 60%, and 68%, respectively (p=0.07, p=0.175, and p=0.160). CONCLUSIONS: Prophylactic administration of intravenous magnesium sulfate prevents increases in the QT and QTc interval 30 minutes after the last infusion of ibutilide.

Aged↗

PubMed2002