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Biomedical subjects

C R Conti

Publications and source records attributed to C R Conti.

At least 19 recordsLinked to original sources

Inhibition of sodium-dependent calcium overload to treat myocardial ischemia.

Because intracellular sodium and calcium overload play a key role in both mechanical and electrical dysfunction during myocardial ischemia, inhibition of the late sodium current would be expected to decrease the intracellular sodium and calcium overloads and thereby reduce their undesirable effects. Ranolazine selectively inhibits late sodium current relative to peak sodium current, and attenuates the abnormalities of ventricular repolarization and contractility associated with ischemia. This is the currently proposed mechanism (hypothesis) of action of the effects of ranolazine during myocardial ischemia.

Acetanilides↗

Ibutilide: efficacy and safety in atrial fibrillation and atrial flutter in a general cardiology practice.

BACKGROUND: Published experience with ibutilide (IB) in randomized clinical trials reveals that conversion to sinus rhythm (SR) occurs in 31% of patients with atrial fibrillation (AF) and in 63% of patients with atrial flutter. HYPOTHESIS: The study was undertaken to test the efficacy and safety of IB in patients with AF and with atrial flutter and to compare them with those reported in previous studies. METHODS: In a general cardiology practice, 54 consecutive patients with AF or atrial flutter, no contraindication to IB, and a normal QTc interval, were treated with intravenous IB (0.4-2.0 mg). Duration of arrhythmia, left atrial (LA) size, ejection fraction (EF), time to conversion, QTc interval, and adverse drug events were determined. Patients were observed for a minimum of 6 h. Successful cardioversion was defined as arrhythmia termination within 6 h. RESULTS: Twenty-four of 34 (70.6%) patients with AF and 15 of 20 (75%) patients with atrial flutter converted to SR. Conversion of AF to SR was more likely to occur if duration of AF was approximately 96 h compared with > 96 h (81 vs. 17%, respectively; p = 0.006). The mean time to arrhythmia termination was 68.8 min. Left atrial size, determined by echocardiogram, was 44 +/- 13 mm in 43 patients. Patients with LA size approximately 45 mm had a conversion rate of 55% in both AF and flutter, compared with a conversion rate of 72% in patients with LA size < 45 mm. Ejection fraction was not a predictor of drug success. The QTc intervals were significantly prolonged after IB administration, with a mean change of 47.1 ms for successfully treated patients. Sustained polymorphic ventricular tachycardia occurred in one patient within 1 min of IB infusion, requiring electrical cardioversion to SR. This patient's serum electrolytes and QTc interval were normal prior to IB infusion; however, the QTc increased by 160 ms (from 387 to 547 ms) during drug infusion. No systemic or pulmonary emboli occurred. CONCLUSION: The efficacy of IB for conversion of AF to SR in this prospective observational study was considerably better than previously reported. Duration of AF remains an important predictor of conversion to SR. Complications are rare and without long-term adverse effects.

Aged↗

How will INVEST and other hypertension trials change clinical practice?

Three large, ongoing, international clinical trials will greatly improve our understanding of hypertension management. The trials, which include the INternational VErapamil SR/trandolapril STudy (INVEST), the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), and the Controlled ONset Verapamil INvestigation of Cardiovascular Endpoints (CONVINCE) trial, enrolled a combined total of 81,649 patients over a 7-year period from 18 different countries in North America, South America, Europe, and Australia-Asia. The mean age of all subjects was 66 years, and the mean body mass index (BMI) was 29.5. In addition, 30% of all patients had diabetes and 43% had documented coronary artery disease (CAD). In INVEST, 100% of enrolled patients had documented CAD and 27% had diabetes. Of patients treated for 12 months in INVEST, a systolic blood pressure (SBP) <140 mmHg was achieved by 70% of nondiabetics, and 66% of patients with diabetes achieved that level. Of all the patients enrolled in the three trials, 38% were smokers, 25% had a history of myocardial infarction (MI) or stroke, and 52% had a history of dyslipidemia. Although these clinical trials are likely to influence treatment guidelines, they may not affect the way medicine is practiced. A survey of primary care physicians found that 41% had not heard of or were not familiar with the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI) guidelines. The JNC VI and European guidelines provide management strategies based on severity of coronary risk factors, target organ damage, and blood pressure levels. Primary care physicians have a responsibility to be educated about risk stratification, goals of treatment based on risk, and management strategies for hypertension from available treatment guidelines.

Aged↗

Updated pathophysiologic concepts in unstable coronary artery disease.

BACKGROUND: The clinical syndrome of unstable angina has multiple causes; different therapies therefore may be indicated in different patients. METHODS: Recent publications on unstable coronary artery disease were reviewed to identify pathophysiologic phenomena and concepts that can aid decision-making in the clinical management of patients with unstable coronary artery disease of different causes. RESULTS: The fate of any coronary plaque depends on local and systemic factors. Autopsy studies have revealed that plaques most likely to rupture are those with a soft lipid core covered by a thin fibrous cap that may be inflamed. Systemic factors such as hypertension may be maximally expressed at the site of plaques that are prone to rupture. If an unstable plaque is identified, local therapy, such as angioplasty, stents, or radiation, and aggressive systemic therapy, such as lipid lowering, diabetes control, and hypertension control, can be used. CONCLUSIONS: Specific therapy for acute symptoms can be used if the specific cause of the unstable state can be identified. Failure of the plaque to stabilize may result in recurrent ischemia, biochemical evidence for myocardial damage, and evidence of an inflammatory process. These factors influence prognosis; cardiac events occur more commonly when they are present.

Angina, Unstable↗