Potential role of the microvasculature in progression of heart failure

The Eye as the Window to the Heart: Optical Coherence Tomography Angiography Biomarkers as Indicators of Cardiovascular Disease

Alterations in microvasculature represent some of the earliest pathological processes across a wide variety of human diseases. In many organs, however, inaccessibility and difficulty in directly imaging tissues prevent the assessment of microvascular changes, thereby significantly limiting their translation into improved patient care. The eye provides a unique solution by allowing for the non-invasive and direct visualization and quantification of many aspects of the human microvasculature, including biomarkers for structure, function, hemodynamics, and metabolism. Optical coherence tomography angiography (OCTA) studies have specifically identified reduced capillary densities at the level of the retina in several eye diseases including glaucoma. This narrative review examines the published data related to OCTA-assessed microvasculature biomarkers and major systemic cardiovascular disease. While loss of capillaries is being established in various ocular disease, pilot data suggest that changes in the retinal microvasculature, especially within the macula, may also reflect small vessel damage occurring in other organs resulting from cardiovascular disease. Current evidence suggests retinal microvascular biomarkers as potential indicators of major systemic cardiovascular diseases, including systemic arterial hypertension, atherosclerotic disease, and congestive heart failure.

Ocular Alterations Associated with Primary Congenital Heart Disease - A Cross-sectional Study

OBJECTIVE

The objective of the study was to asses ocular findings' prevalence in children with primary congenital heart disease (CHD).

PATIENTS AND METHODS

This is a prospective cross-sectional study of children with CHD treated at a specialized center in the South of Brazil between 2013 and 2015. They underwent a complete ocular examination, including measurement of visual acuity, refraction test, external motility, anterior and posterior biomicroscopy, and binocular indirect fundoscopy with retinal photographs. Two experienced examiners independently assessed fundus findings: one at the time of examination and image capture, while the other assessed only the captured images.

RESULTS

Of a total of 146 children examined, 124 were included in this analysis (16% loss). Seventy children were male (55.5%). The average age was 9.3 years (minimum 1 month and maximum 15 years). Caucasians race were 81.2%, African Descendants race were 11.1%, and others were 7.7%. About 57.1% had already had heart surgery. About 14.8% had visual acuity below 0.6 and 2.8% below 0.1. Strabismus was found in 7.4% and cataracts in 1.7%. Retinal alterations were recognized in 13.5%, of which 4.8% were related to vascular narrowing or dilation and/or abnormal arteriovenous crossing; 7.14% were related to increased vascular tortuosity, while 1.6% were related to active toxoplasmic chorioretinitis lesions. Concomitant abnormalities in ocular motility, biomicroscopy, or ophthalmoscopy were detected in 24% of the cases.

CONCLUSION

Children under the age of 15 years old with primary CHD have a high prevalence of ocular alterations, with external ocular and retinal manifestations, with higher occurrence rate among cyanotic cases. This leads us to strongly recommend the performance of a complete ophthalmological examination in such cases.

Lumen narrowing and increased wall to lumen ratio of retinal microcirculation are valuable biomarkers of hypertension-mediated cardiac damage

Purpose: In the course of hypertension, left ventricular hypertrophy and diastolic dysfunction develop very often and may progress toward heart failure. The aim of the study was to analyze the relationship between abnormalities of retinal microcirculation and cardiac damage defined as left ventricular hypertrophy and/or diastolic dysfunction. Materials and methods: The study comprised 88 patients with essential hypertension. The group was divided into two subgroups: hypertensives without cardiac damage (n = 55) and with cardiac damage (n = 33). Control group comprised 32 normotensive subjects. Scanning laser Doppler flowmetry was used to evaluate retinal microcirculation. Echocardiography was used to assess cardiac damage. Results: Lumen diameter of retinal arterioles was significantly smaller in patients with cardiac damage vs. controls (77 vs. 84 µm, p = 0.02). Additionally, there was an evident trend with respect to lumen diameter (LD) across all three studied subgroups; i.e.: the smallest dimeters were present in cardiac damage patients, moderate size in hypertensives' without cardiac damage, and the largest diameters in healthy controls (pfor trend < 0.01). Lumen diameter was inversely correlated with cardiac intraventricular septum diameter (R = -0.25, p = 0.02), left ventricular mass (R = -0.24, p = 0.02), and left atrial volume (R = -0.22, p = 0.04). Wall to lumen ratio was associated with intraventricular septum diameter (R = 0.21, p = 0.044) and left atrial volume (R = 0.21, p = 0.045). In multivariable regression analysis, lumen diameter was independently associated with intraventricular septum diameter (β = -0.05, p = 0.03), left ventricular mass (β = -1.15, p = 0.04), and left atrial volume (β = -0.42, p = 0.047); wall to lumen ratio was independently associated with intraventricular septum diameter (β = 3.67, p = 0.02) and left atrial volume (β = 30.0, p = 0.04). Conclusions: In conclusion, retinal arterioles lumen diameter and wall to lumen ratio were independent biomarkers of cardiac damage. Retinal examination performed by means of scanning laser Doppler flowmetry might be a valuable tool to improve cardiovascular risk stratification of hypertensive patients.

Prevalence of ophthalmological abnormalities in children and adolescents with CHD: systematic review and meta-analysis of observational studies

BACKGROUND

CHDs form a complex and heterogeneous group of clinical entities, with high morbidity and mortality. With the advancement of surgical and invasive techniques and clinical treatment, the survival of these patients has increased significantly, and there are reports of a high prevalence of ocular abnormalities in this group. The objective of this study was to estimate the prevalence of ocular findings in children and adolescents diagnosed with CHD.

METHODS

A systematic search was conducted in the following databases: MEDLINE (via PubMed), EMBASE, and Cochrane CENTRAL, in addition to a manual search on studies published on the patient, from inception until August, 2014. Observational studies assessing the prevalence of ocular abnormalities in children and adolescents with CHDs were included.

RESULTS

Of the 2413 articles identified, eight were included, comprising a total of 1061 patients. Among them, the lowest and highest prevalences observed were 6.3 and 65%, respectively. The weighted average prevalence of ocular abnormalities was 32.5% (CI95% 19.3-49.3). Strabismus, cataracts, and retinopathy were the most frequently observed alterations.

CONCLUSION

The prevalence of ocular abnormalities in children and adolescents with CHDs was 32.5%, demonstrating that ocular consequences are not uncommon in this population and may have relevant clinical impact. These results reinforce the need for ophthalmological evaluation of patients with CHDs.

Low-grade inflammation and endothelial dysfunction explain the association between retinopathy and left ventricular ejection fraction in men: an 8-year follow-up of the Hoorn Study

PURPOSE

The aim of this study was to prospectively investigate the association of retinopathy with changes in left ventricular (LV) function.

METHODS

Within the Hoorn Study, a population-based cohort study of diabetes in The Netherlands, retinal photography and echocardiography were performed in the year 2000 (baseline) and 2008 (follow-up). Retinopathy was graded according to the Eurodiab classification and further defined as absent or present retinopathy. LV systolic and diastolic functions were assessed by LV ejection fraction (%), LV mass (g/m(2.7)) and left atrial (LA) volume indices and the ratio of LV inflow (E) and early diastolic lengthening (e') velocities. Linear regression analyses stratified for sex were completed to investigate associations of retinopathy with changes in LV function in participants with impaired glucose metabolism and type 2 diabetes.

RESULTS

One hundred forty-seven participants (58% men, mean age 66) were included in the study, of whom 13.6% were present with retinopathy at baseline. LV ejection fraction was similar among participants with and without retinopathy (60.2% versus 60.7%) at baseline. Eight years later, retinopathy was significantly associated with a lower LV ejection fraction (β -8.0 95% CI -15.37 to -0.68) in men, independent of risk factors. Microvascular endothelial dysfunction ([ED] β -4.87 95% CI -13.40 to 3.67) and low-grade inflammation ([LGI] β -5.30 95% CI -13.72 to 3.12) both diminished the association. No significant associations between retinopathy and other LV function parameters were observed.

CONCLUSION

Retinopathy was significantly associated with a lower LV ejection fraction in men but not in women. LGI and ED might explain the observed association.

Subfoveal choroidal thickness in patients with chronic heart failure analyzed by spectral-domain optical coherence tomography

PURPOSE

To evaluate the subfoveal choroidal thickness (SFCT) measured by enhanced depth imaging optical coherence tomography (EDI-OCT) in eyes of chronic heart failure (CHF) patients.

METHODS

Fifty-six patients with CHF and 56 age- and gender-matched healthy individuals were enrolled. The SFCT was measured by EDI-OCT. The ejection fraction of left ventricle (EFLV), age, intraocular pressure (IOP), axial length (AL), systolic and diastolic blood pressure, and ocular perfusion pressure (OPP) were also measured.

RESULTS

Mean SFCT was 181.2 ± 80.23 μm in the study group and 283.6 ± 52.4 μm in the control group (p = 0.000). There was a statistically significant correlation between the SFCT and each of EFLV and age. SFCT value was not statistically significantly associated with AL, IOP and OPP.

CONCLUSION

Our results suggest that SFCT is lower in eyes of CHF patients compared to age- and gender-matched healthy individuals.

Simvastatin reverses cardiac hypertrophy caused by disruption of the bradykinin 2 receptor

Bradykinin 2 receptor (B2R) deficiency predisposes to cardiac hypertrophy and hypertension. The pathways mediating these effects are not known. Two-month-old B2R knockout (KO) and wild-type (WT) mice were assigned to 4 treatment groups (n = 12-14/group): control (vehicle); nitro-L-arginine methyl ester (L-NAME) an NO synthase inhibitor; simvastatin (SIM), an NO synthase activator; and SIM+L-NAME. Serial echocardiography was performed and blood pressure (BP) at 6 weeks was recorded using a micromanometer. Myocardial eNOS and mitogen-activated protein kinase (MAPK, including ERK, p38, and JNK) protein expression were measured. Results showed that (i) B2RKO mice had significantly lower ejection fraction than did WT mice (61% +/- 1% vs. 73% +/- 1%), lower myocardial eNOS and phospho-eNOS, normal systolic BP, and higher LV mass, phospho-p38, and JNK; (ii) L-NAME increased systolic BP in KO mice (117 +/- 19 mm Hg) but not in WT mice and exacerbated LV hypertrophy and dysfunction; and (iii) in KO mice, SIM decreased hypertrophy, p38, and JNK, improved function, increased capillary eNOS and phospho-eNOS, and prevented L-NAME-induced LV hypertrophy without lowering BP. We conclude that disruption of the B2R causes maladaptive cardiac hypertrophy with myocardial eNOS downregulation and MAPK upregulation. SIM reverses these abnormalities and prevents the development of primary cardiac hypertrophy as well as hypertrophy secondary to L-NAME-induced hypertension.

Regular aspirin use and retinal microvascular signs: the Blue Mountains Eye Study

OBJECTIVE

Hypertension is closely related to microvascular abnormalities and there is increasing interest in agents that target the microvasculature. The effect of aspirin on the microvasculature has not been well studied. We examined the cross-sectional and longitudinal associations between regular aspirin use and retinal microvascular signs.

DESIGN AND METHODS

We digitized retinal photographs from participants of the Blue Mountains Eye Study cohort (1992-1994, n = 3654, aged over 49 years, and 1997-1999, n = 2335) and used a computer-assisted method to measure average retinal arteriolar and venular diameters. Information on the frequency of aspirin use was collected, with regular aspirin use defined as weekly or daily.

RESULTS

Regular aspirin users comprised 21.2% (n = 775) of the baseline population. At baseline and in individuals who were on one or more antihypertensive medication, regular aspirin use was found to be associated with retinal arterioles on average 3.6 mum (95% confidence interval 1.0, 6.2) wider than those of non-users or occasional aspirin users, after adjusting for age, blood pressure, smoking, diabetes, non-steroidal anti-inflammatory drug use and other variables. Increasing frequency of aspirin use was associated with increasing retinal arteriolar diameter (Ptrend < 0.01). At 5-year follow-up, regular users of aspirin and antihypertensive medication(s) had wider retinal arterioles than those who used aspirin less regularly. Neither antihypertensive medication use alone nor aspirin use alone was associated with wider retinal vessels.

CONCLUSION

Our finding of a possible association between the combined use of aspirin and antihypertensive agent(s) and wider retinal arteriolar diameter warrants further investigation into the effects of aspirin on the microvasculature.

Are retinal microvascular abnormalities associated with large artery endothelial dysfunction and intima-media thickness? The Hoorn Study

It has been hypothesized that microvascular dysfunction affects endothelial dysfunction of the large arteries, which may explain the relationship of microvascular disease with macrovascular disease. The aim of the present study was to investigate the relationship of retinal microvascular disorders with endothelium-dependent FMD (flow-mediated vasodilatation) and carotid IMT (intima-media thickness). A total of 256 participants, aged 60–85 years, 70 with normal glucose metabolism, 69 with impaired glucose metabolism and 109 with Type II diabetes, were included in this study. All participants were ophthalmologically examined, including funduscopy and two field 45° fundus photography, and were graded for retinal sclerotic vessel abnormalities and retinopathy. Retinal arteriolar and venular diameters were measured with a computer-assisted method. Brachial artery, endothelium-dependent FMD and carotid IMT were assessed ultrasonically as measurements of endothelial function and early atherosclerosis respectively. After adjustment for age, sex and glucose tolerance status, retinal vessel diameters, retinal sclerotic vessel abnormalities and retinopathy were not significantly associated with FMD. In contrast with other retinal microvascular abnormalities, retinal venular dilatation was associated with increased IMT [standardized β value (95% confidence interval), 0.14 (0.005–0.25)]. This association was attenuated and lost statistical significance after adjustment for cardiovascular risk factors, in particular after correction for fasting insulin. In the present study, retinal microvascular disorders are not independently associated with impaired FMD. In addition, retinal venular dilatation is associated with increased IMT, although non-significantly after multivariable adjustment for cardiovascular risk factors. Therefore our data provide evidence that retinal microvascular disease is of limited value in risk stratification for future cardiovascular events.

Coronary Flow Reserve by Contrast Enhanced Transesophageal Coronary Sinus Doppler Measurements Can Evaluate Diabetic Microvascular Dysfunction

BACKGROUND

This study was undertaken to investigate whether coronary flow reserve (CFR) using coronary sinus flow (CSF), which can be measured by transesophageal Doppler echocardiography (TEDE), especially when contrast enhanced, is useful in evaluating microvascular dysfunction in patients with diabetes mellitus (DM).

METHODS AND RESULTS

CSF recordings using contrast enhanced TEDE were performed before and after adenosine triphosphate infusion (0.15 mg x kg(-1) x min(-1)) in 16 patients with type 2 DM and diabetic retinopathy and in 13 non-DM patients (control). Coronary angiography revealed normal epicardial coronary arteries. CFR was defined as the ratio of the antegrade flow velocity time integral in hyperemic conditions and basal levels. Clear envelopes of CSF were obtained in all DM patients using contrast-enhanced TEDE. CFR using CSF in the DM group was significantly decreased compared with the control group (1.4+/-0.4 vs 2.1+/-0.5, p<0.01), but there were no significant differences of age, ejection fraction, rate of hypertension and hypercholesterolemia between the 2 groups. Using 1.7 of CFR as the cut-off value, diabetic microvascular dysfunction could be detected with 82% sensitivity and 83% specificity.

CONCLUSIONS

CFR calculated by CSF using contrast-enhanced TEDE may be useful for evaluating diabetic microvascular dysfunction.

The VEGF +405 CC Promoter Polymorphism is Associated With an Impaired Prognosis in Patients With Chronic Heart Failure: A MERIT-HF Substudy

BACKGROUND

A common polymorphism positioned at +405 of the vascular endothelial growth factor (VEGF) gene is known to influence VEGF protein production. In contrast, a second polymorphism, positioned at -460 polymorphism, has no reported functional effects. VEGF is linked to angiogenesis and might directly influence the clinical outcome of patients with chronic heart failure (CHF). We investigated the association between two VEGF polymorphisms and morbidity and mortality in patients with CHF.

METHODS AND RESULTS

VEGF promoter polymorphisms +405 and -460 were examined in 596 CHF patients enrolled in the Metoprolol CR/XL Randomized Intervention Trial in Heart Failure (MERIT-HF) study and in 187 healthy controls. In CHF patients, a risk ratio for each genotype was calculated using the combined endpoint of all-cause mortality or hospitalization. The allele frequencies of the +405 and -460 polymorphisms for the CHF cohort and for 187 healthy controls were not significantly different. However, the presence of the +405 CC genotype (frequency 0.14) was independently associated with an adverse outcome as described by the MERIT study combined endpoint compared with the +405 GG genotype (risk ratio 1.65; 95%CI 1.03-2.64; P = .039). The -460 polymorphism was not associated with an altered prognosis ( P = .60).

CONCLUSION

Our results indicate that the VEGF +405 CC genotype is associated with an adverse clinical outcome in patients with CHF. This genotype has been associated with lower plasma VEGF levels, suggesting a possible mechanism of action for the gene variant. This belief is further supported by the fact that the VEGF -460 polymorphism, which does not affect plasma VEGF levels, did not adversely affect the prognosis.

Myocardial blood flow in patients with dilated cardiomyopathy: Quantitative assessment with velocity-encoded cine magnetic resonance imaging of the coronary sinus

PURPOSE

To quantify global myocardial perfusion using magnetic resonance imaging (MRI) in patients with heart failure due to idiopathic dilated cardiomyopathy (IDC) and to compare myocardial perfusion and microvascular reactivity with healthy subjects.

MATERIALS AND METHODS

A total of 19 subjects (healthy volunteers (N = 12) and IDC patients (N = 7)) were studied using cine MRI to measure left ventricular (LV) mass and a velocity-encoded cine MRI technique to measure coronary sinus flow at rest and after dipyridamole-induced hyperemia. Absolute values of total myocardial blood flow (MBF) were calculated from coronary sinus flow and LV mass.

RESULTS

At baseline, MBF was not significantly different in patients with IDC (0.48 +/- 0.07 mL/minute/g) and healthy subjects (0.55 +/- 0.19 mL/minute/g, P= 0.41). After dipyridamole administration, MBF in IDC patients increased to a level significantly less than that in normal volunteers (1.05 +/- 0.35 mL/minute/g vs. 1.99 +/- 1.05 mL/minute/g, P < 0.05). Consequently, MBF reserve was impaired in patients with IDC (2.19 +/- 0.77) compared to that in healthy subjects (3.51 +/- 1.29, P < 0.05). A moderate correlation was found between MBF reserve and LV ejection fraction (r = 0.48, P < 0.05).

CONCLUSION

MBF reserve is reduced in patients with IDC, indicating that coronary microcirculatory flow is impaired. This integrated MRI approach allows quantitative measurement of global MBF in humans and may have the potential to study the effects of pharmacological interventions on myocardial perfusion.

Simvastatin preserves cardiac function in genetically determined cardiomyopathy

Endothelial dysfunction characterizes heart failure (HF). Simvastatin (Sim) increases endothelial nitric oxide (NO) independent of lipid-lowering. We evaluated the effect of Sim on cardiac function, apoptosis, and NO availability in HF. Five-month-old cardiomyopathic (CM) hamsters were divided into 2 groups: Sim (20 mg/kg, 6 weeks, n = 6) and Untreated (n = 6). Age-matched normal hamsters served as controls (n = 6). Serial echocardiograms were performed to measure LV function. Myocardial apoptosis, eNOS, and capillary density were measured at 6 weeks. Cardiomyopathic hamsters had lower LV shortening fraction (SF) compared with controls (17 +/- 3% vs 59 +/- 2%), higher LV end-diastolic volume (30 +/- 3 vs 6 +/- 2 mL/m2), and lower LV mass/volume ratio (0.5 +/- 0.04 vs 0.72 +/- 0.02 mg/ml, P < 0.001). During follow-up, SF decreased (9 +/- 2%) and LV volume increased (38 +/- 1 mL/m2) in untreated hamsters (P < 0.05 from baseline) but did not change significantly in the Sim group (P < 0.05 vs untreated). Myocardial caspase-3 activity was higher and apoptotic nuclear density was lower in Sim compared with untreated CM hamsters (0.072 +/- 0.02% vs 0.107 +/- 0.03%, P < 0.01). Myocardial capillary density was highest in the Sim group (P < 0.05). eNOS expression was not different between groups. Sim retards the progression of HF in CM hamsters. This may be related to an increase in coronary microvasculature, increase in NO availability, and decreased apoptosis.

Effects of intraaortic balloon augmentation in a porcine model of endotoxemic shock

OBJECTIVE

Patients with septic shock commonly have myocardial dysfunction associated with lactic acid production and troponin I release. The purpose of this study was to evaluate the effects on intraaortic balloon pump (IABP) support on myocardial dysfunction.

DESIGN

Prospective, randomized controlled study.

SETTING

Animal research laboratory.

METHODS

Ten pigs had arterial, pulmonary arterial, and coronary catheters inserted. After receiving endotoxin infusion over 30 min, half the animals received IABP support.

RESULTS

Coronary sinus lactic acid levels (P< 0.05 for both 90 min versus baseline and 60 min versus baseline) and arterial lactic acid levels (P < 0.05 for both 90 min versus baseline and 60 min versus baseline) increased with time but did not differ between IABP and sham groups. While overall there was no difference with time in myocardial lactic acid consumption or production (calculated as arterial lactic acid level minus coronary sinus lactic acid level), the IABP group showed net myocardial lactic acid consumption at 90 min, while the sham group showed myocardial lactic acid production. Three of five animals in each group showed troponin I release. The levels were similar and did not differ between groups.

CONCLUSION

IABP had no benefits in this porcine model of endotoxemic shock.

Relation of Myocardial Blood Volume to Left Ventricular Function and Future Cardiac Events in Patients With Idiopathic Dilated Cardiomyopathy

BACKGROUND

The hypothesis that myocardial blood volume is associated with left ventricular (LV) dysfunction and future cardiovascular events in patients with idiopathic dilated cardiomyopathy (IDC) was tested using intravenous myocardial contrast echocardiography (MCE).

METHODS AND RESULTS

Thirty-five patients with IDC and 10 age-matched healthy control subjects were enrolled. Using MCE, background-subtracted and peak myocardial contrast intensity (calibrated PMCI) were calculated as measures of myocardial blood volume. LV ejection fraction (LVEF) was calculated using the modified Simpson method. Patients with IDC were stratified into 2 groups according to the median value of the calibrated PMCI [high value group (n=17): calibrated PMCI > or = -22.7 dB, low value group (n=18): calibrated PMCI < -22.7 dB]. The calibrated PMCI was markedly reduced in patients with IDC compared with the control subjects (p=0.0025) and closely related to LVEF (r=0.688, p<0.0001). In the multivariate model, calibrated PMCI was the independent variable that predicted cardiac events in patients with IDC. According to the Kaplan-Meier analysis, cardiac event-free rates were significantly lower in the low-value group than in the high-value group (p<0.01).

CONCLUSIONS

Myocardial blood volume is closely related to LV dysfunction and future cardiac events in patients with IDC.

Individuals at increased coronary heart disease risk are characterized by an impaired microvascular function in skin

BACKGROUND

To investigate whether microvascular function in skin is a valid model to study the relationships between cardiovascular risk factors and microvascular function, we investigated skin microvascular function in individuals with increased coronary heart disease (CHD) risk.

MATERIALS AND METHODS

Forty-six healthy White individuals aged 30-70 years were studied. Coronary heart disease risk was assessed with the use of the CHD risk score according to the Framingham Heart Study, which is based on the risk factors age, blood pressure, cigarette smoking, total cholesterol, HDL cholesterol and diabetes. Endothelium-dependent and -independent vasodilation in skin were evaluated with laser Doppler after iontophoresis of acetylcholine and sodium nitroprusside. Videomicroscopy was used to measure recruitment of skin capillaries after arterial occlusion.

RESULTS

Coronary heart disease risk score (i.e. the 10-year probability of CHD) varied from 1-37%. Microvascular function decreased with increasing quartiles of CHD risk (for acetylcholine-mediated vasodilation: 687, 585, 420 and 326%, P = 0.002; for nitroprusside-mediated vasodilation: 776, 582, 513 and 366%, P = 0.02; for capillary recruitment: 49.9, 44.6, 27.2 and 26.7%, P = 0.001). These trends were similar in men and women (P for interaction > 0.2) and independent of body mass index.

CONCLUSIONS

Increased CHD risk is associated with an impaired endothelium-dependent vasodilatation and capillary recruitment in skin, suggesting that microvascular function in skin is a valid model to study the relationships between cardiovascular risk factors and microvascular function.

Effects of intravenous amlodipine on coronary hemodynamics in subjects with angiographically normal coronary arteries

The aim of the current study was to assess the ability of amlodipine to dilate the coronary vessels in subjects with angiographically normal coronary arteries and normal left ventricular function. Ten patients, six women and four men (mean age 48 +/- 14 years, range 25-67 years) were enrolled. Coronary flow velocity and coronary perfusion pressure were invasively measured at baseline, during intracoronary adenosine (1-mg bolus) and at 5, 15, and 30 min following IV amlodipine (10 or 20 mg). Quantitative coronary angiography was performed at baseline and at 5, 15, and 30 min after amlodipine. Coronary cross-sectional area and mean coronary flow velocity progressively increased after amlodipine administration, resulting in an average increase in coronary flow at 30 min of 76%. On an individual basis, all patients but one showed a consistent trend toward a progressive coronary vasodilator effect of amlodipine over time. The peak effect of amlodipine on baseline mean coronary flow velocity was 43 +/- 12% that of adenosine. This is the first clinical study demonstrating that the IV administration of amlodipine produces a powerful coronary vasodilatation in subjects with angiographically normal coronary arteries and normal ventricular function, besides its known systemic vasodilating effects. The coronary vasodilating properties of amlodipine are particularly expressed at the microcirculatory level.

Abnormal contractile responses during dobutamine stress echocardiography in patients with idiopathic dilated cardiomyopathy

BACKGROUND

In chronic heart failure augmented wall stress leads to increased energy demand. Supply, however, may be reduced due to coronary vasoconstriction and endothelial dysfunction. This might lead to a mismatch between demand and supply. In the present study we further explored the effect of increased demand during dobutamine stress echocardiography.

METHODS AND RESULTS

Sixteen patients with idiopathic dilated cardiomyopathy (mean age 44+/-13 years, New York Heart Association class II-III, mean left ventricular ejection fraction 0.27+/-0.10) underwent dobutamine stress echocardiography (5-40 microg/min per kg bodyweight+atropine if required). Wall motion and thickening was assessed in 16 segments using a four-point scale. Eleven patients (69%) showed regions with worsening of wall motion or a biphasic response during dobutamine infusion. Of the remaining five patients one patient did not show any wall motion changes and one patient showed a partial improvement while only in three patients wall motion improvement in the whole heart was found.

CONCLUSION

A majority of patients with idiopathic dilated cardiomyopathy showed decreased wall motion during increased demand, i.e. ischemia-like myocardial contractile responses during dobutamine stress echocardiography. These findings further support the concept that an energy mismatch between demand and supply might play a pathophysiological role in idiopathic dilated cardiomyopathy.

Adenosine preconditions against endothelin-induced constriction of coronary arterioles

Myocardial hypoperfusion is accompanied by concomitant increases in adenosine and endothelin-1 (ET-1) production, but the vasodilatory effect of adenosine prevails over that of ET-1. Therefore, we hypothesized that adenosine-induced or ischemic preconditioning reduces the vasoconstrictive effect of ET-1. Coronary arteriolar diameter in vivo was measured using fluorescence microangiography in anesthetized open-thorax dogs. ET-1 (5 ng. kg(-1). min(-1) administered intracoronary, n = 10) induced progressive constriction over 45 min [25 +/- 6% (SE)]. The constriction was blocked by preconditioning with adenosine (25 microgram. kg(-1). min(-1) administered intracoronary) for 20 min and 10 min of washout (n = 10) or attenuated by ischemic preconditioning (four 5-min periods of ischemia, 9 +/- 5% at 45 min). To investigate the receptor involved in this process, coronary arterioles (50-150 micrometer) were isolated and pressurized at 60 mmHg in vitro. The ET-1 dose-response curve (1 pM-5 nM) was rightward shifted after preconditioning with adenosine (1 microM) for 20 min and 10 min of washout (n = 11). Blockade of A(2) receptors [8-(3-chlorostyryl)caffeine, 1 microM, n = 9] but not A(1) receptors (8-cyclopentyl-1,3-dipropylxanthine, 100 nM, n = 7) prevented this shift. These results suggest that adenosine confers a vascular preconditioning effect, mediated via the A(2) receptor, against endothelin-induced constriction. This effect may offer a new protective function of adenosine in preventing excessive coronary constriction.

Advances in the molecular mechanisms of heart failure

Congestive heart failure is a common clinical problem resulting in significant morbidity and mortality. Although considerable progress has been made in elucidating the pathophysiologic mechanisms that lead to the development of this process, much remains unknown. The techniques of modern molecular biology now allow a detailed and systematic analysis of this disease. Recent data linking cardiac hypertrophy, aberrant signaling, or cytoskeletal abnormalities to the development of heart failure have provided new insights into this process. These studies have confirmed the importance of many classical pathways but also revealed novel pathways. This review will focus on the recent advances that have been made and will highlight the importance they have had in our understanding and treatment of heart failure.