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Verrier, Richard

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Verrier

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Richard

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Verrier, Richard
Author's Publications: search.filters.isAuthorOfPublication.e01fac7f-7d35-451b-99f6-ed6d3bc10268

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Now showing 1 - 6 of 6
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    Atrial Septum Fat Deposition and Atrial Anatomy Assessed by Cardiac Magnetic Resonance: Relationship to Atrial Electrophysiology
    (BioMed Central, 2012) Rizzi, Patricia B; Mewton, Nathan; Tereshchencko, Larisa G; Strauss, David G; Liu, Chia-Ying; Marchlinski, Francis E; Spooner, Peter M; Kellman, Peter; Lima, Joao A; Verrier, Richard; Cox, Christopher; Nearing, Bruce
    To assess the prevalence of fat deposition in the atrial septum with and its relationship with 12-lead electrocardiogram (ECG) atrial parameters (PR interval, P wave duration) and the presence of atrial fibrillation.
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    Mechanisms of ranolazine's dual protection against atrial and ventricular fibrillation
    (Oxford University Press, 2012) Verrier, Richard; Kumar, Kapil; Nieminen, Tuomo; Belardinelli, Luiz
    Coronary artery disease and heart failure carry concurrent risk for atrial fibrillation and life-threatening ventricular arrhythmias. We review evidence indicating that at therapeutic concentrations, ranolazine has potential for dual suppression of these arrhythmias. Mechanisms and clinical implications are discussed.
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    Mechanisms of Inhaled Fine Particulate Air Pollution–induced Arterial Blood Pressure Changes
    (National Institute of Environmental Health Sciences, 2008) Bartoli, Carlo R.; Wellenius, Gregory A.; Diaz, Edgar; Lawrence, Joy; Coull, Brent; Akiyama, Ichiro; Lee, Lani M.; Okabe, Kazunori; Verrier, Richard; Godleski, John
    Background: Epidemiologic studies suggest a positive association between fine particulate matter and arterial blood pressure, but the results have been inconsistent. Objectives: We investigated the effect of ambient particles on systemic hemodynamics during a 5-hr exposure to concentrated ambient air particles (CAPs) or filtered air (FA) in conscious canines. Methods: Thirteen dogs were repeatedly exposed via permanent tracheostomy to CAPs (358.1 ± 306.7 μg/m\(^3\), mean ± SD) or FA in a crossover protocol (55 CAPs days, 63 FA days). Femoral artery blood pressure was monitored continuously via implanted telemetry devices. We measured baroreceptor reflex sensitivity before and after exposure in a subset of these experiments (n = 10 dogs, 19 CAPs days, 20 FA days). In additional experiments, we administered α-adrenergic blockade before exposure (n = 8 dogs, 16 CAPs days, 15 FA days). Blood pressure, heart rate, rate–pressure product, and baroreceptor reflex sensitivity responses were compared using linear mixed-effects models. Results: CAPs exposure increased systolic blood pressure (2.7 ± 1.0 mmHg, p = 0.006), diastolic blood pressure (4.1 ± 0.8 mmHg; p < 0.001), mean arterial pressure (3.7 ± 0.8 mmHg; p < 0.001), heart rate (1.6 ± 0.5 bpm; p < 0.001), and rate–pressure product (539 ± 110 bpm × mmHg; p < 0.001), and decreased pulse pressure (−1.7 ± 0.7 mmHg, p = 0.02). These changes were accompanied by a 20 ± 6 msec/mmHg (p = 0.005) increase in baroreceptor reflex sensitivity after CAPs versus FA. After α-adrenergic blockade, responses to CAPs and FA no longer differed significantly. Conclusions: Controlled exposure to ambient particles elevates arterial blood pressure. Increased peripheral vascular resistance may mediate these changes, whereas increased baroreceptor reflex sensitivity may compensate for particle-induced alterations in blood pressure.
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    Concentrated Ambient Particles Alter Myocardial Blood Flow During Acute Ischemia in Conscious Canines
    (National Institute of Environmental Health Sciences, 2008) Bartoli, Carlo R.; Wellenius, Gregory A.; Coull, Brent; Akiyama, Ichiro; Diaz, Edgar; Lawrence, Joy; Okabe, Kazunori; Verrier, Richard; Godleski, John
    Background: Experimental and observational studies have demonstrated that short-term exposure to ambient particulate matter (PM) exacerbates myocardial ischemia. Objectives: We conducted this study to investigate the effects of concentrated ambient particles (CAPs) on myocardial blood flow during myocardial ischemia in chronically instrumented conscious canines. Methods: Eleven canines were instrumented with a balloon occluder around the left anterior descending coronary artery and catheters for determination of myocardial blood flow using fluorescent microspheres. Telemetric electrocardiographic and blood pressure monitoring was available for four of these animals. After recovery, we exposed animals by inhalation to 5 hr of either filtered air or CAPs (mean concentration ± SD, 349.0 ± 282.6 μg/m\(^{3}\)) in a crossover protocol. We determined myocardial blood flow during a 5-min coronary artery occlusion immediately after each exposure. Data were analyzed using mixed models for repeated measures. The primary analysis was based on four canines that completed the protocol. Results: CAPs exposure decreased total myocardial blood flow during coronary artery occlusion by 0.12 mL/min/g (p < 0.001) and was accompanied by a 13% (p < 0.001) increase in coronary vascular resistance. Rate–pressure product, an index of myocardial oxygen demand, did not differ by exposure (p = 0.90). CAPs effects on myocardial blood flow were significantly more pronounced in myocardium within or near the ischemic zone versus more remote myocardium (p interaction < 0.001). Conclusions: These results suggest that PM exacerbates myocardial ischemia by increased coronary vascular resistance and decreased myocardial perfusion. Further studies are needed to elucidate the mechanism of these effects.
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    Air Pollution and ST-Segment Depression in Elderly Subjects
    (National Institue of Environmental Health Sciences, 2005) MacCallum, Gail; Canner, Marina J.; Gold, Diane; Litonjua, Augusto A.; Zanobetti, Antonella; Coull, Brent; Schwartz, Joel; Verrier, Richard; Nearing, Bruce; Suh MacIntosh, Helen H.; Stone, Peter
    Increased levels of daily ambient particle pollution have been associated with increased risk of cardiovascular morbidity. Black carbon (BC) is a measure of the traffic-related component of particles. We investigated associations between ambient pollution and ST-segment levels in a repeated-measures study including 269 observations on 24 active Boston residents 61–88 years of age, each observed up to 12 times from June through September 1999. The protocol involved continuous Holter electrocardiogram monitoring including 5 min of rest, 5 min of standing, 5 min of exercise outdoors, 5 min of recovery, and 20 cycles of paced breathing. Pollution-associated ST-depression was estimated for a 10th- to 90th-percentile change in BC. We calculated the average ST-segment level, referenced to the P-R isoelectric values, for each portion of the protocol. The mean BC level in the previous 12 hr, and the BC level 5 hr before testing, predicted ST-segment depression in most portions of the protocol, but the effect was strongest in the postexercise periods. During post-exercise rest, an elevated BC level was associated with −0.1 mm ST-segment depression (p = 0.02 for 12-hr mean BC; p = 0.001 for 5-hr BC) in continuous models. Elevated BC also predicted increased risk of ST-segment depression ≥0.5 mm among those with at least one episode of that level of ST-segment depression. Carbon monoxide was not a confounder of this association. ST-segment depression, possibly representing myocardial ischemia or inflammation, is associated with increased exposure to particles whose predominant source is traffic.