Progression of coronary endothelial dysfunction in man and its potential clinical significance

Imaging Assessment of Endothelial Function: An Index of Cardiovascular Health

Endothelial dysfunction is a key early mechanism in a variety of cardiovascular diseases and can be observed in larger conduit arteries as well as smaller resistance vessels (microvascular dysfunction). The presence of endothelial dysfunction is a strong prognosticator for cardiovascular events and mortality, and assessment of endothelial function can aid in selecting therapies and testing their response. While the gold standard method of measuring coronary endothelial function remains invasive angiography, several non-invasive imaging techniques have emerged for investigating both coronary and peripheral endothelial function. In this review, we will explore and summarize the current invasive and non-invasive modalities available for endothelial function assessment for clinical and research use, and discuss the strengths, limitations and future applications of each technique.

A retrospective cohort of coronary artery disease development after at least two angiograms in patients with normal coronary angiograms or mild coronary artery disease

Background

Coronary Artery Disease is one of the leading causes of death in the world. CAD usually progresses slowly during time and patients with normal or near-normal coronary arteries are also at risk of developing CAD. It is now believed that even mild atherosclerosis can increase the rate of CAD.

Methods

This is a retrospective, descriptive and analytic study. We selected patients who had undergone at least two diagnostic coronary angiographies at Tehran Heart Center and had normal coronary structure or mild CAD in initial angiography. The data was obtained from the Tehran Heart Center Angiography Databank. Predicting factors in the development of CAD were determined.

Results

Data on 556 patients were reviewed. The median interval between the initial and final coronary catheterization was 37.6 months. On the final evaluation, 216 patients (38.8%) found to have developed some degrees of coronary artery disease. Based on the multivariate analysis, age, hematocrit, cigarette smoking, hypertension, and initial presentation with stable and unstable angina were found to be independent predictors of progression to CAD in patients.

Conclusion

In the end, 40% of patients who had normal coronary arteries or minimal CAD in the initial angiography report, developed some degrees of CAD and some clinical indices can predict the risk of CAD.

Effect of Nearby Construction Activity on Endothelial Function, Sensitivity to Nitric Oxide, and Potassium Channel Activity in the Middle Cerebral Arteries of Rats

The present study assessed the effect of nearby construction activity on the responses of rat middle cerebral arteries (MCA)to the endothelium-dependent vasodilator acetylcholine and the NO donor sodium nitroprusside (SNP) and the activity of MaxiK potassium channels in MCA smooth muscle cells from male Sprague-Dawley rats. Two monitoring systems were used to assess vibrations in the animal rooms during and immediately after construction activities near the research building where the animal facility is located. One was a commercially available system; the other was a Raspberry-Pi (RPi)-based vibration monitoring system designed in our laboratory that included a small computing unit attached to a rolling sensor (low sensitivity) and a piezoelectric film sensor (high sensitivity). Both systems recorded increased levels of vibration during construction activity outside the building. During the construction period, vasodilator responses to acetylcholine and SNP were abolished, and MaxiK single-channel current opening frequency and open-state probability in cell-attached patches of isolated MCA myocytes were dramatically decreased. Recovery of acetylcholine- and SNP-induced dilation was minimal in MCA from rats studied after completion of construction but housed in the animal facility during construction, whereas responses to acetylcholine and SNP were intact in rats purchased, housed, and studied after construction. Baseline levels of vibration returned after the completion of construction, concomitant with the recovery of normal endothelium-dependent vasodilation to acetylcholine and of NO sensitivity assessed by using SNP in MCA from animals obtained after construction. The results of this study indicate that the vibration associated with nearby construction can have highly disruptive effects on crucial physiologic phenotypes.

Morphological and functional evaluation of the bioresorption of the bioresorbable everolimus-eluting vascular scaffold using IVUS, echogenicity and vasomotion testing at two year follow-up: a patient level insight into the ABSORB A clinical trial

The aim of this study was to describe vaso-reactivity (by Acetylcholine and Methergine tests) at 2 year follow-up in parallel with the individual changes in the echogenicity characteristics of the polymer struts of the everolimus eluting bioresorbable vascular scaffold (BVS), from post-treatment to 2 year follow-up, in patients enrolled in the ABSORB Cohort A study. Intravascular ultrasound assessment was performed with a phased array catheter (EagleEye, Volcano Corporation, Cordova, CA, USA) with automated pullback at 0.5 mm per second. The % ratio at 6 months and 2 years [(Scaffold Area post PCI- Lumen Area)/Scaffold Area post PCI] was calculated as a measure of scaffold shrinkage. The % change of hyperechogenicity was defined as: ([post-procedural hyperechogenicity] - [2 year follow up hyperechogenicity])/[post-procedural hyperechogenicity]) × 100. The vasomotion test with intracoronary acetylcholine (10(-6) M) or intravenous methergine (0.4 mg) was performed at 2 years. Overall nine patients received all these analyses and were enrolled in the present analysis. A 50-96% reduction in hyperechogenicity was observed between baseline and 2 years, which corresponded to a change in vasoreactivity between 2 and 22%. A vasoconstriction of the scaffolded segment was observed in the 5 patients, who underwent the methergine test, with a mean decrease in lumen diameter after methergine of 9 ± 7% (P = 0.06), while vasodilatation occurred in the 4 patients who underwent the acetylcholine test with a mean increase in lumen diameter after acetylcholine of 8 ± 5% (P = 0.125). Bioresorption of the BVS is accompanied by re-establishment of both endothelial and non-endothelial dependent vasomotion.

Blood pressure in young adulthood and the risk of type 2 diabetes in middle age

OBJECTIVE

Hypertension is known to accompany type 2 diabetes in middle age, but it is unknown how early in life blood pressure (BP) begins to rise among individuals who later develop diabetes. The objective of this study was to evaluate elevated BP as a long-term predictor of type 2 diabetes.

RESEARCH DESIGN AND METHODS

We conducted a prospective cohort study of 1,152 white male medical students in The Johns Hopkins Precursors Study to longitudinally assess systolic BP (SBP) and diastolic BP (DBP) from young adulthood through middle age in men who went on to develop diabetes. Incident diabetes was identified by self-report through mailed questionnaires verified by medical record review.

RESULTS

During a median follow-up of 38 years, 77 cases of incident diabetes occurred. The mean age of diabetes diagnosis was 58 years. As early as age 30 years, mean SBP and DBP were significantly higher in men who developed diabetes during follow-up than in those who remained nondiabetic (SBP 122 vs. 119 mmHg, P = 0.009; DBP 78 vs. 75 mmHg, P = 0.0005). The rate of increase in SBP and DBP over time in men who developed diabetes was greater than the rate of increase in men who did not develop diabetes (SBP 0.49 vs. 0.27 mmHg/year, P < 0.00003; DBP 0.24 vs. 0.17 mmHg/year; P = 0.09). After adjustment for BMI and other risk factors for diabetes, SBP and DBP at age 30 years remained significantly higher in individuals who developed diabetes than in their nondiabetic counterparts; however, the difference in the rate of increase in SBP was no longer significant following multivariate adjustment.

CONCLUSIONS

BP elevations precede the development of type 2 diabetes in middle age by 20-25 years. Higher BP in the prediabetic state might contribute to the presence of vascular disease at the time of diagnosis of type 2 diabetes.

Exaggerated reactivity to mental stress is associated with exercise-induced myocardial ischemia in an asymptomatic high-risk population

BACKGROUND

This study was done to determine whether cardiovascular reactivity to mental stress is associated with exercise-induced occult ischemia in an asymptomatic population at high risk for premature coronary heart disease (CHD).

METHODS AND RESULTS

One hundred fifty-two siblings of persons with premature CHD underwent mental stress testing. Exercise thallium tomography and 24-hour Holter monitoring were also performed. Hemodynamic changes were monitored during both stressors. Siblings positive for exercise-induced ischemia were offered cardiac catheterization. During mental stress, siblings with an abnormal exercise ECG and/or thallium scan (n=15) had greater maximal increases in systolic blood pressure (SBP, P=.0004) and diastolic blood pressure (DBP, P=.05) and had greater heart rate variability in the normalized low frequency domain of an analysis of Holter monitor recordings, compared with siblings without exercise-induced ischemia. Coronary arteriography confirmed coronary atherosclerosis in 85% of siblings with exercise-induced ischemia. Regression analyses showed that occult ischemia during exercise was a strong independent predictor of maximal change in SBP and DBP during mental stress. A multivariate logistic model demonstrated that siblings with exercise-induced occult ischemia were 21 times more likely to be "hot" responders (top quartile of change in SBP and DBP) during mental stress.

CONCLUSIONS

An exaggerated cardiovascular response to mental stress is associated with exercise-induced myocardial ischemia in persons with preclinical coronary heart disease.