Increased cancer rates in patients with chronic hepatitis C.

AIMS: As previous reports show an association of chronic hepatitis C (HCV) with hepatocellular carcinoma (HCC) and non-liver cancers, we examine the association of HCV with liver cancer and non-liver cancers. METHODS: Retrospective cross-sectional study at Kaiser Permanente Southern California (KPSC) evaluating HCV and non-HCV patients from 1 January 2008 to 12 December 2012. Cancer diagnoses were obtained from the KPSC-SEER-affiliated registry. Logistic regression analyses were used for rate ratios and time-to-event analyses were performed using Cox proportional hazards models, adjusted for age, gender, race, smoking and cirrhosis. Cancer rate ratios were stratified by tobacco, alcohol abuse, diabetes and body mass index (BMI). RESULTS: The initial population and final population of multivariable analysis were N = 5 332 903 and N = 2 080 335 respectively. Cancer burden (all sites) was significantly higher in HCV than in non-HCV patients and HCV patients had a high rate of liver cancer. When liver cancer was excluded, cancer rates remained significantly increased in HCV. Unadjusted cancer rates were significantly higher in HCV compared to non-HCV for oesophageal, stomach, colorectal, pancreas, myeloma, non-Hodgkin's lymphoma, head/neck, lung, renal and prostate cancer. After stratification for alcohol abuse, tobacco, diabetes and BMI, increased cancer rates remained significant for all cancer sites, liver cancer and non-Hodgkin's lymphoma. Multivariable analyses demonstrated a strong correlation between cirrhosis and cancer. Tobacco use and diabetes were also associated with cancer. In the absence of cirrhosis, HCV, tobacco use and diabetes significantly increased the cancer risk. Mediation analyses showed that cirrhosis was responsible for a large proportion on the effect of HCV on cancer risk. CONCLUSION: This study supports the concept of HCV as a systemic illness and treating HCV regardless of disease severity and prior to progression to cirrhosis.

Comparative Effectiveness and Safety of Drug Prophylaxis for Prevention of Venous Thromboembolism After Total Knee Arthroplasty.

BACKGROUND: Rates of venous thromboembolism in contemporary studies of primary total knee arthroplasty (TKA) have been reported to be as high as 3.5%. Although drug prophylaxis is effective, the best option among these regimens is not well established. The purpose of this study was to evaluate the comparative effectiveness and safety of aspirin, low-molecular-weight heparin, synthetic pentasaccharide factor Xa inhibitors, and vitamin K antagonist. METHODS: Data were from a US total joint replacement registry, with 30,499 patients receiving unilateral TKA from May 16, 2006, to December 31, 2013. Patients received either aspirin (324-325 mg daily), enoxaparin (40-60 mg daily), fondaparinux (2.5 mg daily), or warfarin (all doses) and were followed up 90 days postoperatively on several outcomes: deep vein thrombosis, pulmonary embolism, major bleeding, wound complications, infection, and death. RESULTS: There was no evidence that fondaparinux, enoxaparin, or warfarin were superior to aspirin in the prevention of pulmonary embolism, deep vein thrombosis, or venous thromboembolism or that aspirin was safer than these alternatives. However, enoxaparin was found to be as safe as aspirin with respect to bleeding, and fondaparinux was as safe as aspirin for risk of wound complications. CONCLUSION: Among TKA patients, we did not find evidence for decreased effectiveness or increased safety with use of aspirin, but enoxaparin had comparable safety to aspirin for bleeding and fondaparinux had comparable safety to aspirin for wound complications.

What Doesn't Kill You Makes You Fitter: A Systematic Review of High-Intensity Interval Exercise for Patients with Cardiovascular and Metabolic Diseases.

High-intensity interval exercise (HIIE) has gained popularity in recent years for patients with cardiovascular and metabolic diseases. Despite potential benefits, concerns remain about the safety of the acute response (during and/or within 24 hours postexercise) to a single session of HIIE for these cohorts. Therefore, the aim of this study was to perform a systematic review to evaluate the safety of acute HIIE for people with cardiometabolic diseases. Electronic databases were searched for studies published prior to January 2015, which reported the acute responses of patients with cardiometabolic diseases to HIIE (≥80% peak power output or ≥85% peak aerobic power, VO2peak). Eleven studies met the inclusion criteria (n = 156; clinically stable, aged 27-66 years), with 13 adverse responses reported (~8% of individuals). The rate of adverse responses is somewhat higher compared to the previously reported risk during moderate-intensity exercise. Caution must be taken when prescribing HIIE to patients with cardiometabolic disease. Patients who wish to perform HIIE should be clinically stable, have had recent exposure to at least regular moderate-intensity exercise, and have appropriate supervision and monitoring during and after the exercise session.

Adherence to statins and LDL-cholesterol goal attainment.

OBJECTIVES: To examine the relationship between low-density lipoprotein cholesterol (LDL-C) goal attainment and adherence to statin medications in patients with coronary artery disease (CAD). STUDY DESIGN: Cross-sectional study of CAD patients 18 years of age or older in an integrated healthcare system. METHODS: Patients dispensed 2 or more statin prescriptions between May 2009 and May 2010, were identified. Medication possession ratio (MPR) was calculated to estimate adherence. The LDL-C value closest to May 27, 2010, was used to determine goal. Adherence and LDL-C goal were defined as 80% or greater MPR and less than 100 mg/dL or less than 70 mg/dL, respectively. Electronic medical records were used to identify patient demographics and clinical information. Logistic regression was used to estimate the effect of these factors on goal attainment. RESULTS: A total of 67,100 CAD patients were identified. Overall, 85.8% had LDL-C less than 100 mg/dL, 32.4% had LDL less than 70 mg/dL, and 79.8% were adherent to their statin medication. Over 65% of patients not at LDL-C goal less than 100 mg/dL were adherent. Among patients with LDL-C less than 100 mg/dL, 17.9% were not adherent. Increasing medication adherence was associated with improved LDL-C levels. Adherence to statins, male sex, Asian and Hispanic race/ethnicity, a higher number of concurrent prescriptions, higher Charlson Comorbidity Index, and hypertension were associated with LDL-C goal attainment. CONCLUSIONS: Incorporating LDL-C levels and medication adherence at the point of care allows providers to focus interventions to address either adherence challenges or the need for medication titration in an effort to improve LDL-C goal attainment and ultimately reduce morbidity and mortality.

The prevalence and trends of antiviral medication use during pregnancy in the US: a population-based study of 664,297 deliveries in 2001-2007.

To evaluate the prevalence, trends, timing and duration of exposure to antiviral medications during pregnancy within a US cohort of pregnant women and to evaluate the proportion of deliveries with a viral infection diagnosis among women given antiviral medication during pregnancy. Live-born deliveries between 2001 and 2007, to women aged 15-45 years, were included from the Medication Exposure in Pregnancy Risk Evaluation Program, a collaborative research program between the U.S. Food and Drug Administration and eleven health plans. They were evaluated for prevalence, timing, duration, and temporal trends of exposure to antiviral medications during pregnancy. We also calculated the proportion of deliveries with a viral infection diagnosis among those exposed to antiviral medications. Among 664,297 live births, the overall prevalence of antiviral exposure during pregnancy was 4 % (n = 25,155). Between 2001 and 2007, antiviral medication exposure during pregnancy doubled from 2.5 to 5 %. The most commonly used antiviral medication was acyclovir, with 3 % of the deliveries being exposed and most of the exposure occurring after the 1st trimester. Most deliveries exposed to antiviral medications were exposed for less than 30 days (2 % of all live births). Forty percent of the women delivering an infant exposed to antiviral medications had a herpes diagnosis. Our findings highlight the increased prevalence of women delivering an infant exposed to antiviral medications over time. These findings support the need for large, well-designed studies to assess the safety and effectiveness of these medications during pregnancy.

Medication exposure in pregnancy risk evaluation program: the prevalence of asthma medication use during pregnancy.

Asthma is one of the most common chronic diseases in women of reproductive age, occurring in up to 8 % of pregnancies. The objective of this study is to assess the prevalence of asthma medication use during pregnancy in a large diverse cohort. We identified women aged 15-45 years who delivered a live born infant between 2001 and 2007 across 11 U.S. health plans within the Medication Exposure in Pregnancy Risk Evaluation Program (MEPREP). Using health plans' administrative and claims data, and birth certificate data, we identified deliveries for which women filled asthma medications from 90 days before pregnancy through delivery. Prevalence (%) was calculated for asthma diagnosis and medication dispensing. There were 586,276 infants from 575,632 eligible deliveries in the MEPREP cohort. Asthma prevalence among mothers was 6.7 %, increasing from 5.5 % in 2001 to 7.8 % in 2007. A total of 9.7 % (n = 55,914) of women were dispensed asthma medications during pregnancy. The overall prevalence of maintenance-only medication, rescue-only medication, and combined maintenance and rescue medication was 0.6, 6.7, and 2.4 % respectively. The prevalence of maintenance-only use doubled during the study period from 0.4 to 0.8 %, while rescue-only use decreased from 7.4 to 5.8 %. In this large population-based pregnancy cohort, the prevalence of asthma diagnoses increased over time. The dispensing of maintenance-only medication increased over time, while rescue-only medication dispensing decreased over time.

Build it and they will come: outcomes from a successful cardiac rehabilitation program at an Aboriginal Medical Service.

OBJECTIVE: Cardiovascular disease (CVD) is the leading disease burden in Aboriginal Australians, but culturally appropriate cardiac rehabilitation programs are lacking. We evaluated the uptake and effects on lifestyle, and cardiovascular risk factors, of cardiac rehabilitation at an Aboriginal Medical Service (AMS). METHODS: The program involved weekly exercise and education sessions (through 'yarning') for Aboriginal people with or at risk of CVD. Participants' perceptions of the program and the impact on risk factors were evaluated following 8 weeks of attendance. RESULTS: In twenty-eight participants (20 females) who completed 8 weeks of sessions, body mass index (34.0 ± 5.1 v. 33.3 ± 5.2 kgm⁻²; P<0.05), waist girth (113 ± 14 v. 109 ± 13 cm; P<0.01) and blood pressure (135/78 ± 20/12 v. 120/72 ± 16/5 mmHg; P<0.05) decreased and 6- min walk distance increased (296 ± 115 v. 345 ± 135m; P<0.01). 'Yarning' helped identify and address a range of chronic health issues including medication compliance, risk factor review and chest pain management. CONCLUSIONS: AMS-based cardiac rehabilitation was well attended, and improved cardiovascular risk factors and health management. An AMS is an ideal location for managing cardiovascular health and provides a setting conducive to addressing a broad range of chronic conditions.

A large, population-based study of 2009 pandemic Influenza A virus subtype H1N1 infection diagnosis during pregnancy and outcomes for mothers and neonates.

BACKGROUND: Pregnant women were at increased risk for serious outcomes of 2009 pandemic influenza A virus subtype H1N1 (influenza A[H1N1]pdm09) infection, but little is known about the overall impact of the pandemic on neonatal and maternal outcomes. METHODS: We identified live births that occurred from 1 July 2008 through 31 May 2010 in 5 Kaiser Permanente regions. Pregnant women were considered to have influenza if they had a positive result of a laboratory test for influenza virus or if they received a diagnosis of influenza during a period in which seasonal influenza virus or A(H1N1)pdm09 was the predominant circulating virus. RESULTS: There were 111 158 births from 109 015 pregnancies involving 107 889 mothers; 368 pregnant women (0.3%) received a diagnosis of influenza due to seasonal virus, and 959 (0.9%) received a diagnosis of influenza due to A(H1N1)pdm09; 107 688 did not receive an influenza diagnosis. Pregnant women with influenza due to A(H1N1)pdm09 were more likely than women with seasonal influenza infection to be hospitalized within 30 days of the diagnosis (27% vs 12%; odds ratio [OR], 2.84 [95% confidence interval {CI}, 2.01-4.02]). Pregnant women with A(H1N1)pdm09 who started antiviral treatment ≥2 days after the diagnosis were significantly more likely to be hospitalized than those who started antiviral treatment <2 days after diagnosis (OR, 3.43 [95% CI, 1.55-7.56]). Mothers with seasonal influenza virus infection had an increased risk for having a small-for-gestational-age infant (OR, 1.59 [95% CI, 1.15-2.20]). CONCLUSIONS: In this large, geographically diverse population, A(H1N1)pdm09 infection increased the risk for hospitalization during pregnancy. Late initiation of antiviral treatment was also associated with an increased risk for hospitalization.

Impact of MMRV combination vaccine on childhood vaccination compliance.

OBJECTIVE: To assess the impact of using the combined measles, mumps, rubella, and varicella vaccine (MMRV) instead of the measles, mumps, and rubella vaccine and the varicella vaccine separately (MMR+V) on uptake of vaccines recommended by the Advisory Committee for Immunization Practices (ACIP) in young children. STUDY DESIGN: Retrospective cohort study. METHODS: Electronic immunization records of children 12 to 15 months of age who received either MMR+V (n = 29,716) or MMRV (n = 29,711) between November 2003 and June 2007 while enrolled in Kaiser Permanente Southern California were evaluated. Proportions of children who received either MMRV or MMR+V and other ACIP-recommended vaccines either simultaneously or during recommended age intervals were compared. RESULTS: Concomitant administration of DTaP (76.3 vs 75.6%), PCV7 (89.1 vs 78.6%), Hib (92.3 vs 91.3%), and hepatitis A vaccine (HAV) (44.2 vs 0.1%) and on-time administration of PCV7 (91.7 vs 78.7%), Hib (93.9 vs 93.2%), and HAV (86.8 vs 24.3%) were greater with MMRV than with MMR+V. On-time administration of DTaP (91.4 vs 90.5%) and IPV (91.3 vs 90.0%) was greater with MMR+V than with MMRV. CONCLUSIONS: Concomitant and on-time administration of most ACIP-recommended vaccines was greater with MMRV than with MMR+V despite the addition of HAV to the recommended schedule after introduction of MMRV. However, the modest compliance increases suggest that focusing on other barriers to compliance may be important to increasing adherence to future vaccination recommendations.

The positive predictive value of a hyperkalemia diagnosis in automated health care data.

PURPOSE: Our objectives were to determine performance of coded hyperkalemia diagnosis at identifying (1) clinically evident hyperkalemia and (2) serum potassium>6 mmol/L. METHODS: This retrospective observational study included 8722 patients with diabetes within an integrated healthcare system who newly initiated an angiotensin converting enzyme inhibitor, angiotensin receptor blocker, or spironolactone. The primary outcome was first hyperkalemia-associated event (hospitalization, emergency department visit or death within 24 hours of coded diagnosis and/or potassium≥6 mmol/L) during the first year of therapy. Medical records were reviewed. RESULTS: Among a random sample of 99 patients not coded as having hyperkalemia, none had hyperkalemia upon record review. Among all 64 patients identified as having hyperkalemia, all had hospitalization or emergency department visit associated with coded diagnosis or elevated potassium. Of 55 with coded diagnosis, 42 (PPV 76%) had clinically evident hyperkalemia; 32 (PPV 58%) had potassium≥6. Of 9 identified using only potassium≥6, 7 (PPV 78%) had clinically evident hyperkalemia. CONCLUSIONS: Nearly one-fourth of patients with coded diagnosis do not have clinically evident hyperkalemia and nearly one-half do not have potassium≥6. Because both false positives and negatives occur with coded diagnoses, medical record validation of hyperkalemia-associated outcomes is necessary.

Diabetes and drug-associated hyperkalemia: effect of potassium monitoring.

BACKGROUND: Renin-angiotensin-aldosterone system (RAAS) inhibitors are associated with hyperkalemia, but there is little evidence demonstrating patients who receive potassium monitoring have a lower rate of hyperkalemia. OBJECTIVE: To evaluate the association between potassium monitoring and serious hyperkalemia-associated adverse outcomes among patients with diabetes newly initiating RAAS inhibitor therapy. DESIGN: Retrospective observational study. PARTICIPANTS: Patients with diabetes without end-stage renal disease initiating RAAS inhibitor therapy between 2001 and 2006 at three integrated health care systems. MEASUREMENTS: Potassium monitoring and first hyperkalemia-associated adverse event during the initial year of therapy. Hyperkalemia-associated adverse events included hospitalizations, emergency department visits or deaths within 24 h of hyperkalemia diagnosis and/or diagnostic potassium >or=6 mmol/l. Incidence rates were calculated in person-years (p-y). We used inverse probability propensity score weighting to adjust for differences between patients with and without monitoring; Poisson regression was used to obtain adjusted relative risks. RESULTS: A total of 19,391 of 27,355 patients (71%) received potassium monitoring. Serious hyperkalemia-associated events occurred at an incidence rate of 10.2 per 1,000 p-y. Compared to patients without monitoring, adjusted relative risk of hyperkalemia-associated adverse events among all patients with monitoring was 0.50 (0.37, 0.66); in the subset of patients who also had chronic kidney disease (n = 2,176), adjusted relative risk was 0.29 (0.18, 0.46). CONCLUSIONS: Patients prescribed RAAS inhibitors who have both diabetes and chronic kidney disease and receive potassium monitoring are less likely to experience a serious hyperkalemia-associated adverse event compared to similar patients who did not receive potassium monitoring. This evidence supports existing consensus-based guidelines.

Increasingly restrictive definitions of hyperkalemia outcomes in a database study: effect on incidence estimates.

PURPOSE: To determine the incidence of hyperkalemia-associated adverse outcomes among ambulatory patients with diabetes newly initiating renin-angiotensin-aldosterone system (RAAS) inhibitor therapy and to examine to what extent increasingly restrictive definitions of hyperkalemia-associated outcomes influenced incidence estimates. METHODS: Retrospective cohort study of 27 355 individuals with diabetes who were new users of RAAS inhibitors at three integrated healthcare systems. RESULTS: Using the least restrictive definition of hyperkalemia-associated outcome, an ambulatory visit (AV), inpatient hospitalization (IP), or emergency department (ED) visit co-occurring within 7 days of coded hyperkalemia diagnosis and/or potassium concentration of > or =5.5 mmol/L, the incidence rate of hyperkalemia was 30.1 per 1000 person-years (p-y). Restricting to only IP or ED visits co-occurring within 24 hours of coded diagnosis and/or potassium > or =6 mmol/L, the incidence rate was 10.2 per 1000 p-y. When this latter definition was further restricted by removing available potassium laboratory values, the incidence rate declined to 9.5 per 1000 p-y. CONCLUSIONS: Modifying the definition of hyperkalemia-associated outcome resulted in up to threefold differences in incidence rate estimates. Our results demonstrate the value of including potassium laboratory results and AVs in identifying hyperkalemia from electronic data. Comparing incidence estimates across published studies requires consideration of differences in outcome definitions.

Validation of patient-reported joint counts in rheumatoid arthritis and the role of training.

OBJECTIVE: To demonstrate the effectiveness of simple training on improving the ability of patients with rheumatoid arthritis (RA) to assess joint swelling, and to validate the use of a computerized questionnaire, the Health Assessment Questionnaire (HAQ-ulous), to collect patient-reported tender and swollen joint counts. METHODS: Sixty patients completed the HAQ-ulous, reporting pain and swelling of the 28 joints included in the Disease Activity Score-28. A rheumatologist blinded to the patients' responses assessed each joint for the presence of tenderness and swelling. At followup visits, 30 patients received training in distinguishing a swollen joint from a chronically enlarged joint, completed the HAQ-ulous again, and were reassessed by the physician. RESULTS: At the initial visit, a strong correlation was shown between patient- and clinician-reported tender joints [Pearson correlation coefficient (r(p)) = 0.79; p < 0.0001]. Correlation between patient- and clinician-reported swollen joints was less robust (r(p) = 0.41; p = 0.001). Following training at the second visit, agreement between patients and the clinician improved for both tender joints (r(p) = 0.94; p < 0.0001) and swollen joints (r(p) = 0.93; p < 0.0001). CONCLUSION: With simple training in distinguishing swollen joints from chronically enlarged joints, the majority of patients are able to accurately assess joint swelling. Objective tools, such as the HAQ-ulous, that incorporate patient-reported outcomes are a valuable and reliable addition to standard clinical practice for monitoring patients with RA.

The 6-minute walk test does not reliably detect changes in functional capacity of patients awaiting cardiac transplantation.

BACKGROUND: Peak oxygen consumption (Vo(2)peak) is a strong independent predictor of prognosis in patients with severe chronic heart failure (CHF) and is used to guide optimal timing of transplantation. However, its assessment is relatively expensive and time-consuming and requires sophisticated equipment and highly trained personnel. The purpose of this study was to determine whether changes in 6-minute walk test (6WT) distance, a simple, inexpensive potential alternative measure of functional capacity, can predict changes in Vo(2)peak in patients with severe CHF. METHODS: Sixteen subjects (ejection fraction 23+/-2%, Vo(2)peak 16.2+/-1.1 ml kg (-1)min(-1)) underwent repeated 6WT and Vo(2)peak assessments that included familiarization and 4 serial measures, 6 weeks apart (baseline and at Weeks 6, 12 and 18). Analysis compared baseline performance with each subsequent testing occasion. RESULTS: At baseline, mean (+/-SE) VO(2)peak was 16.3+/-1.1 ml kg(-1) min(-1) and 6WT distance was 458+/-21 m. 6WT and Vo(2)peak were strongly correlated at all timepoints (average r=0.82; all p<0.05). However, mixed model analysis, assessing the capacity of the changes seen in 6WT to predict changes in Vo(2)peak, showed no statistical significance (F=0.11; p=0.74). CONCLUSIONS: The 6WT is commonly used to assess functional capacity in patients with heart failure. This study demonstrates that, despite a strong cross-sectional correlation with Vo(2)peak, changes in the 6WT are not a reliable predictor of changes in Vo(2)peak within patients. Therefore, the 6WT has limited utility as a serial measure to assess changes in the clinical status of patients with severe heart failure.

Risk of acute myocardial infarction and sudden cardiac death in patients treated with cyclo-oxygenase 2 selective and non-selective non-steroidal anti-inflammatory drugs: nested case-control study.

BACKGROUND: Controversy has surrounded the question about whether high-dose rofecoxib increases or naproxen decreases the risk of serious coronary heart disease. We sought to establish if risk was enhanced with rofecoxib at either high or standard doses compared with remote non-steroidal anti-inflammatory drug (NSAID) use or celecoxib use, because celecoxib was the most common alternative to rofecoxib. METHODS: We used data from Kaiser Permanente in California to assemble a cohort of all patients age 18-84 years treated with a NSAID between Jan 1, 1999, and Dec 31, 2001, within which we did a nested case-control study. Cases of serious coronary heart disease (acute myocardial infarction and sudden cardiac death) were risk-set matched with four controls for age, sex, and health plan region. Current exposure to cyclo-oxygenase 2 selective and non-selective NSAIDs was compared with remote exposure to any NSAID, and rofecoxib was compared with celecoxib. FINDINGS: During 2302029 person-years of follow-up, 8143 cases of serious coronary heart disease occurred, of which 2210 (27.1%) were fatal. Multivariate adjusted odds ratios versus celecoxib were: for rofecoxib (all doses), 1.59 (95% CI 1.10-2.32, p=0.015); for rofecoxib 25 mg/day or less, 1.47 (0.99-2.17, p=0.054); and for rofecoxib greater than 25 mg/day, 3.58 (1.27-10.11, p=0.016). For naproxen versus remote NSAID use the adjusted odds ratio was 1.14 (1.00-1.30, p=0.05). INTERPRETATION: Rofecoxib use increases the risk of serious coronary heart disease compared with celecoxib use. Naproxen use does not protect against serious coronary heart disease.

Effects of exercise training on conduit and resistance vessel function in treated and untreated hypercholesterolaemic subjects.

AIMS: Despite the importance of both lipid metabolism and physical activity to cardiovascular health, few studies have examined the effect of exercise training on vascular function in hypercholesterolaemic humans. METHODS AND RESULTS: A randomized, cross-over design investigated the effect of 8 weeks of combined aerobic and resistance exercise training on conduit and resistance vessel function in 11 untreated subjects with hypercholesterolaemia and 11 subjects taking lipid-lowering medication. High-resolution vascular ultrasonography following forearm ischaemia and glyceryl trinitrate administration determined conduit vessel endothelium-dependent and independent function. Strain-gauge plethysmography, with intra-aerial infusions of acetylcholine, sodium nitroprusside and N(G)-monomethyl-L-arginine, determined resistance vessel function. Flow-mediated dilation and the forearm blood flow response to acetylcholine improved significantly following training in the treated subgroup (both P<0.05) but not the untreated, although the blood flow response to N(G)-monomethyl-L-arginine was augmented following training in the untreated subjects (P<0.05), indicating greater basal nitric oxide bioactivity. Training did not alter responsiveness to glyceryl trinitrate or sodium nitroprusside. CONCLUSIONS: Combined aerobic and resistance training improves endothelium-dependent conduit and resistance vessel function in hypercholesterolaemic subjects taking lipid-lowering medications and basal nitric oxide bioactivity in untreated hypercholesterolaemic subjects. Exercise training may provide additional cardiovascular benefits for hypercholesterolaemic patients including those taking lipid-lowering medication.

Effect of cardiac pacing on forearm vascular responses and nitric oxide function.

We examined the hypothesis that changes in heart rate at rest influence bioactivity of nitric oxide (NO) in humans by examining forearm blood flow responses during cardiac pacing in six subjects. Peak forearm and mean forearm blood flows across the cardiac cycle were continuously recorded at baseline and during pacing, with the use of high-resolution brachial artery ultrasound and Doppler flow velocity measurement. The brachial artery was cannulated to allow continuous infusion of saline or N(G)-monomethyl-L-arginine (L-NMMA). As heart rate increased, no changes in pulse pressure and mean or peak blood flow were evident. L-NMMA had no effect on brachial artery diameter, velocity, or flows compared with saline infusion. These results contrast with our recent findings that exercise involving the lower body, associated with increases in heart rate and pulse pressure, also increased forearm blood flow, the latter response being diminished by L-NMMA. These data suggest that changes in blood pressure, rather than pulse frequency, may be the stimulus for shear stress-mediated NO release in vivo.

Effect of lower limb exercise on forearm vascular function: contribution of nitric oxide.

We examined vascular function in an inactive muscle bed, the forearm, during lower limb exercise and determined the contribution of endothelium-derived nitric oxide (NO) to the hyperemic response. Eight young males were randomized to participate in two studies, each consisting of two bouts of lower limb exercise, separated by a 30-min recovery. Peak forearm blood flow (PFBF) and mean blood flow (MFBF) were continuously recorded at baseline and during exercise using continuous high-resolution vascular ultrasound and Doppler flow velocity measurement. During one session, the brachial artery was cannulated to allow continuous infusion of saline or N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthase. The alternate session was performed to control for possible effects of repeated exercise. At 60, 100, and 160 W, L-NMMA significantly decreased both PFBF and MFBF compared with the saline infusion. These results suggest that systemic production of NO occurs during exercise in resting vessel beds, which do not feed metabolically active tissue. This finding provides a plausible explanation for the antiatherogenic benefits of exercise.

Effect of aerobic and resistance exercise on central hemodynamic responses in severe chronic heart failure.

Exercise is now considered an important component of management in chronic heart failure (CHF), but little is known about central hemodynamic changes that occur during different exercise modalities in these patients. Seventeen patients (ejection fraction 25 +/- 2%) undertook brachial artery and right heart catheterization and oxygen consumption assessment at rest, during submaximal and peak cycling (Cyc), and during submaximal upper and lower limb resistance exercise. Cardiac output (CO) increased relative to baseline during peak Cyc (P < 0.05) but did not change during submaximal Cyc or upper or lower limb exercise. Heart rate (HR) was lowest during upper limb exercise and progressively increased during lower limb exercise, submaximal Cyc, and peak Cyc, with significant differences between each of these (P < 0.01). Conversely, stroke volume (SV) decreased during submaximal Cyc and lower limb exercise and was lower during peak and submaximal Cyc and lower limb exercise than during upper limb exercise (P < 0.05). CHF patients are dependent on increases in HR to increase CO during exercise when SV may decline. Resistance exercise, performed at appropriate intensity, induces a similar hemodynamic burden to aerobic exercise in patients with CHF.

Assessment of brachial artery blood flow across the cardiac cycle: retrograde flows during cycle ergometry.

We describe a novel software system that utilizes automated algorithms to perform edge detection and wall tracking of high-resolution B-mode arterial ultrasound images, combined with synchronized Doppler waveform envelope analysis, to calculate conduit arterial blood flow (BF) across the cardiac cycle. Furthermore, we describe changes in brachial arterial BF to the resting forearm during incremental cycle ergometry in eight subjects. During exercise, peak BF during the cardiac cycle increased at each workload (P < 0.001), because of increased velocity in the presence of unaltered cross-sectional area. In contrast, mean BF calculated across each cardiac cycle decreased at lower workloads before increasing at 100 and 160 W (P < 0.001). Differences in the pattern of peak and mean cardiac cycle flows were due to the influence of retrograde diastolic flow, which had a larger impact on mean flows at lower workloads. In conclusion, BF can be measured with high temporal resolution across the cardiac cycle in humans. Resting brachial arterial flow, including retrograde flow, increases during lower limb exercise.