Arterial Stiffness Is Associated With QTc Interval Prolongation in Patients With Heart Failure.

BACKGROUND: A prolonged corrected QT (QTc) interval is a known risk factor for adverse cardiac events. Understanding the determinants and physiologic correlates of QTc is necessary for selecting proper strategies to reduce the risk of adverse events in high-risk patients. We sought to evaluate the role of arterial stiffness in heart failure as a determinant of QTc prolongation. METHOD: This was an observational study that recruited ambulatory heart failure patients (New York Heart Association Classes I-II) from an outpatient heart failure clinic. In the supine resting position, consented patients underwent noninvasive 12-lead electrocardiograph (ECG) and hemodynamic monitoring using BioZ Dx impedance cardiography. ECGs were evaluated by a reviewer blinded to clinical data, and QTc interval was automatically computed. Patients with pacing or bundle branch block (BBB) were analyzed separately. Strengths of associations were evaluated using Pearson's r coefficients and multivariate linear regression. RESULTS: The final sample ( N = 44) was 62 ± 13 years of age and 64% male with ejection fraction of 34% ± 12%. At univariate level, QTc interval moderately ( r > .50) correlated with cardiac output, left cardiac work index, systemic vascular resistance, and total arterial compliance in patients with intrinsically narrow QRS complexes. At the multivariate level, increasing systemic vascular resistance and decreasing total arterial compliance remained independent predictors of widening QTc interval in this group ( R2 = .54). No significant correlations were seen in patients with pacing or BBB. CONCLUSIONS: In the absence of conduction abnormalities, magnitude of arterial stiffness, an indirect measure of endothelial dysfunction, is associated with QTc interval prolongation.

Impedance Cardiography-Guided Treatment of Hypertension: A Review of the Literature.

BACKGROUND: Hypertension occurs when regulatory mechanisms fail, resulting in increased cardiac output (CO) and/or increased systemic vascular resistance (SVR). Impedance cardiography (ICG) is a non-invasive technology that measures CO and SVR. OBJECTIVE: To assess the literature related to the use of ICG in guiding the selection of anti-hypertensive medications in individuals with hypertension. DESIGN: PubMed and Cumulative Index to Nursing and Allied Health Literature databases were searched for pertinent literature. Only English language, primary research reports published between 1990 and 2014 were included. FINDINGS: The literature demonstrated significant reduction of blood pressure among participants who were treated with ICG-guided selection of anti-hypertensive medications when compared to standard treatment. CONCLUSION: Although the research reviewed is not without limitations (e.g., small sample sizes and small effect sizes), individualized pharmacologic treatment of uncontrolled hypertension based on ICG-obtained hemodynamics seems successful in reducing blood pressure. Further research within the Canadian context that addresses the limitations is warranted.

A prospective study of early ambulation 90 minutes post-left heart catheterization using a retrospective comparison group.

BACKGROUND: Despite a trend toward a reduction in bedrest time after left heart catheterization (LHC) in many Canadian centres, an evidence-based standard of practice has not been established. Canadian bedrest times range from two to four hours post-LHC. Two recent prospective non-randomized studies (n = 1,000) indicate safety of ambulation at 60 and 90 minutes post-LHC. PURPOSE: The purpose of this study was to determine safety of ambulating patients at 90 minutes post-LHC sheath removal compared to the current practice of ambulation at three to four hours post-sheath removal. DESIGN: The study was a prospective non-concurrent design with a retrospective control. METHOD/SAMPLE: Retrospective data from the APPROACH database and chart reviews were analyzed for a period of six months for the control group on the traditional three- to four-hour ambulation protocol (n = 402). Prospective data were gathered for six months for the experimental group (n = 193). RESULTS: There was no difference in complication rates for the two groups. CONCLUSIONS: The results suggest that early ambulation for selected patients at 90 minutes is safe and has the potential to increase both patient comfort and quality of care.

Right ventricular myocardial infarction.

Right ventricular myocardial infarction (RVMI) rarely occurs in isolation. Guidelines recommend that practitioners should evaluate for the presence of an RVMI in a patient with an inferior infarction who is hemodynamically compromised. Diagnostic and treatment modalities for an RVMI can vary from treatments used to treat patients presenting with a left ventricular infarction. This column includes information about the diagnosis management of a patient presenting with an RVMI.

Arrhythmogenic right ventricular cardiomyopathy.

Arrhythmogenic right ventricular cardiomyopathy is a cardiac disorder manifested by the replacement of the ventricular myocardium by fibro fatty tissue and has been known to cause sudden cardiac death in young adults. In 30% to 50% of cases, the disease has familial links, which can have implications for the patients and families involved. Achieving a diagnosis can be taxing on all involved, and for the patient, it can mean having to go through a battery of tests. Once diagnosis has been confirmed, treatment for the disease includes implantation of an implantable defibrillator and/or pharmacotherapy to control the ventricular tachyarrhythmias.