The relationship between diastolic pressure and coronary collateral circulation in patients with stable angina pectoris and chronic total occlusion

The combination approach with Rho-kinase inhibition and mechanical circulatory support in myocardial ischemia-reperfusion injury: Rho-kinase inhibition and ventricular unloading

Background

It remains unclear whether the Rho-kinase (ROCK) inhibition in combination with mechanical circulatory support (MCS) had a synergic protective effect on myocardial ischemia (MI)/reperfusion injury in therapeutic strategies for acute myocardial infarction (AMI). We report the results of an approach using a rat model consisting of a miniaturized cardiopulmonary bypass (CPB) and AMI.

Methods

A total of 25 male Wistar rats were randomized into 5 groups: (1) Sham: a suture was passed under the left anterior descending artery (LAD) creating no MI. A vehicle solution (0.9% saline) was injected intraperitoneally. (2) Myocardial ischemia (MI) + vehicle (MI + V): LAD was ligated for 30 min and reperfused for 120 min, followed by administration of vehicle solution. (3) MI + fasudil (MI + F): the work sequence of group 2, but the selective ROCK inhibitor fasudil (10 mg/kg) was administered instead. (4) MI + V + CPB: CPB was initiated 15 min after the ligation of the LAD to the end of the reperfusion, in addition to the work sequence in group 2. (5) In the MI + F + CPB group, the work sequence of group 4, but with fasudil administration (10 mg/kg).

Results

Measurements of cardiac function through conductance catheter indicated that the drop of + dP/dt after reperfusion was moderately limited in MI + F + CPB (vs. MI + V, dP/dt p = 0.22). The preload recruitable stroke work was moderately improved in the MI + F + CPB (p = 0.23) compared with the corresponding control animals (MI + V). Phosphorylated protein kinase B expression in the MI + V + CPB and MI + F + CPB was higher than that in MI + V (p = 0.33).

Conclusion

Therefore, fasudil administration with MCS resulted in a moderately better left ventricular performance.

Correlation of serum Vascular Endothelial growth factor (VEGF) and cardiovascular risk factors on collateral formation in patients with acute coronary artery syndrome

Coronary collaterals serve as an alternative source of blood flow in obstructive coronary heart disease. Coronary collateral development by releasing various angiogenic growth factors, including vascular endothelial growth factor-A (VEGF-A). Cardiovascular risk factors strongly associated with coronary artery disease include age, sex, elevated serum cholesterol, disturbed carbohydrate metabolism, and elevated blood pressure. A better understanding of the effects of these cardiovascular risk factors and serum VEGF-A level on collateral recruitment is necessary for a better prognosis in coronary artery diseases and new insight for further therapeutic promotion of coronary collaterals.220 consecutive patients undergoing coronary angiography with a mean age of 61 ± 9.83 were selected for the analysis. Two millilitres of blood were taken from the patients for analysis. The blood serum VEGF concentration was quantified via the ELISA method. Angiograms and other clinical reports were collected. Significant coronary artery disease was diagnosed in those with ≥ 70% of stenosis in at least one of the coronary arteries. The angiographic and clinical data were documented. The collateral grading was done according to the Rentrop Scoring system. The serum vascular endothelial growth factor level was correlated with the collateral score and cardiovascular risk factors like age, sex, type ll diabetes, blood pressure, and cholesterol level. An increase in the level of the collateral score was noted with an increase in the level of VEGF in blood serum. A significant association was founded between serum VEGF level and cardiovascular risk factors on collateral formation in patients with diabetes and hypertension. This article is protected by copyright. All rights reserved.

With a Little Help From My Friends: the Role of the Renal Collateral Circulation in Atherosclerotic Renovascular Disease

The collateral circulation can adapt to bypass major arteries with limited flow and serves a crucial protective role in coronary, cerebral, and peripheral arterial disease. Emerging evidence indicates that the renal collateral circulation can similarly adapt and thereby limit kidney ischemia in atherosclerotic renovascular disease. These adaptations predominantly include recruitment of preexisting microvessels for arteriogenesis, with de novo vessel formation playing a limited role. Yet, adaptations of the renal collateral circulation in renovascular disease are often insufficient to fully compensate for the limited flow within an obstructed renal artery and may be hampered by the severity of obstruction or patient comorbidities. Experimental strategies have attempted to circumvent limitations of collateral formation and improve the prognosis of patients with various ischemic vascular territories. These have included pharmacological approaches such as endothelial growth factors, renin-angiotensin-aldosterone system blockade, and If-channel-blockers, as well as interventions like preconditioning, exercise, enhanced external counter-pulsation, and low-energy shock-wave therapy. However, few of these strategies have been implemented in atherosclerotic renovascular disease. This review summarizes current understanding regarding the development of renal collateral circulation in atherosclerotic renovascular disease. Studies are needed to apply lessons learned in other vascular beds in the setting of atherosclerotic renovascular disease to develop new treatment regimens for this patient group.

Metabolic syndrome and its components reduce coronary collateralization in chronic total occlusion: An observational study

Background

Metabolic syndrome (MetS) is an independent risk factor for the incidence of cardiovascular diseases. We investigated whether or to what extent MetS and its components was associated with coronary collateralization (CC) in chronic total occlusion (CTO).

Methods

This study involved 1653 inpatients with CTO. Data on demographic and clinical characteristics were collected by cardiovascular doctors. The CC condition was defined by the Rentrop scoring system. Subgroup analysis, mixed model regression analysis, scoring systems and receiver operating characteristic (ROC) curve analysis were performed.

Results

Overall, 1653 inpatients were assigned to the poor CC group (n = 355) and good CC group (n = 1298) with or without MetS. Compared to the good CCs, the incidence of MetS was higher among the poor CCs for all patients. Poor collateralization was present in 7.6%, 14.2%, 19.3%, 18.2%, 35.6% and 51.1% of the six groups who met the diagnostic criteria of MetS 0, 1, 2, 3, 4 and 5 times, respectively. For multivariable logistic regression, quartiles of BMI remained the risk factors for CC growth in all subgroups (adjusted OR = 1.755, 95% CI 1.510–2.038, P < 0.001 all patients; adjusted OR = 1.897, 95% CI 1.458–2.467, P < 0.001 non-MetS; and adjusted OR = 1.814, 95% CI 1.482–2.220, P < 0.001 MetS). After adjustment for potential confounding factors, MetS was an independent risk factor for CC growth in several models. Assigning a score of one for each component, the AUCs were 0.629 (95% CI 0.595–0.662) in all patients, 0.656 (95% CI 0.614–0.699) in MetS patients and 0.569 (95% CI 0.517–0.621) in non-MetS patients by receiver operating characteristic analysis.

Conclusions

MetS, especially body mass index, confers a greater risk of CC formation in CTO. The value of scoring systems should be explored further for CTO.

Exercise Training as a Mediator for Enhancing Coronary Collateral Circulation: A Review of the Evidence

Coronary collateral vessels supply blood to areas of myocardium at risk after arterial occlusion. Flow through these channels is driven by a pressure gradient between the donor and the occluded artery. Concomitant with increased collateral flow is an increase in shear force, a potent stimulus for collateral development (arteriogenesis). Arteriogenesis is self-limiting, often ceasing prematurely when the pressure gradient is reduced by the expanding lumen of the collateral vessel. After the collateral has reached its self-limited maximal conductance, the only way to drive further increases is to re-establish the pressure gradient.

During exercise, the myocardial oxygen demand is increased, subsequently increasing coronary flow. Therefore, exercise may represent a means of driving augmented arteriogenesis in patients with stable coronary artery disease. Studies investigating the ability of exercise to drive collateral development in humans are inconsistent. However, these inconsistencies may be due to the heterogeneity of assessment methods used to quantify change. This article summarises current evidence pertaining to the role of exercise in the development of coronary collaterals, highlighting areas of future research.

J-shaped curve for cardiovascular mortality: systolic or diastolic blood pressure?

Aggressive reduction of blood pressure (BP) may increase cardiovascular events (the J-curve phenomenon) in certain populations. There is a high number of available studies of antihypertensive treatment that provide strong evidence for J-shaped relationships between both diastolic and systolic BP and main cardiovascular outcomes. Nonetheless, most available studies were observational, and randomized trials might not have or lost their statistical power in post-hoc analysis. Contrariwise, most of prospective trial to demonstrate the benefits of intensive blood pressure control were inconclusive. Therefore, further studies are still necessary in order to clarify this issue.

Donor artery stenosis interactions with diastolic blood pressure on coronary collateral flow in type 2 diabetic patients with chronic total occlusion

Background

We investigated whether and to what extent stenosis of predominant collateral donor artery (PCDA) affects coronary collateral flow in relation to blood pressure (BP) in type 2 diabetic patients with chronic total occlusion (CTO).

Methods

Collateral flow index (CFI) as derived from intracoronary pressure distal to occluded segment and mean aortic pressure in 220 type 2 diabetic patients and 220 propensity score matched non-diabetic controls undergoing percutaneous coronary intervention for CTO. The severity of PCDA stenosis was graded according to lumen diameter narrowing.

Results

CFI decreased stepwise from mild to severe stenosis of the PCDA and was lower in diabetic patients with moderate or severe PCDA stenosis than in non-diabetic controls (0.36 ± 0.10 vs. 0.45 ± 0.08, P < 0.001; 0.29 ± 0.09 vs. 0.35 ± 0.08, P = 0.008). When the PCDA was mildly stenotic, CFI increased initially along with a reduction in diastolic BP, and decreased when diastolic BP was below 60 mmHg in diabetic patients (0.38 ± 0.16 vs. 0.57 ± 0.09, P < 0.001). In the presence of moderate PCDA stenosis, diabetic patients had significantly lower CFI compared to non-diabetic controls, with a relative reduction of 19.8% at diastolic BP 70–79 mmHg, 28.2% at 60–69 mmHg and 38.2% below 60 mmHg (all P < 0.05). A severe PCDA stenosis resulted in a more pronounced decrease in CFI, with a relative reduction of 37.3% for diabetics compared to non-diabetics when diastolic BP was below 60 mmHg (P = 0.050).

Conclusions

In the setting of CTO, donor artery stenosis confers greater risk for reduced coronary collateral flow when diastolic BP is decreased. Even a moderate stenosis in the PCDA may be associated with lower collateral flow as diastolic BP decreases below 80 mmHg in type 2 diabetic than in non-diabetic patients.

Relation Between C-X-C Motif Chemokine Receptor 4 Levels and the Presence and Extent of Angiographic Coronary Collaterals in Patients With Chronic Total Coronary Occlusion

Coronary collateral circulation is an alternative source of blood supply to the myocardium in the presence of chronic total coronary occlusion (CTO). C-X-C motif chemokine receptor 4 (CXCR4) signaling usually contributes to neovascularization. Here, we investigate the relation between CXCR4 levels in peripheral blood CD34+ cells and the formation of angiographic coronary collaterals and determine the risk factors that affect CXCR4 expression in patients with CTO. Demographic, biochemical, and angiographic variables were collected from 324 patients with CTO and 90 negative controls. The presence and extent of collaterals were scored according to the Rentrop scoring system (Rentrop's). CXCR4 levels and plasma biochemical factors were detected. Clinical outcomes were collected during a 12-month follow-up. Results show that low (Rentrop's 0 or 1) and high (Rentrop's of 2 or 3) coronary collateralizations were detected in 183 and 141 patients, respectively. The Rentrop scores were positively correlated with CXCR4 levels in patients with CTO. Patients with low CXCR4 expression exhibited worse clinical outcomes compared with those with high CXCR4 expression. Univariate correlation analysis revealed that age of ≥65 years, women, diabetes, increased plasma level of high-sensitivity C-reactive protein (hs-CRP), and N-terminal brain-type natriuretic peptide were associated with low CXCR4 levels. In conclusion, CXCR4 levels were positively correlated with the presence and extent of angiographic coronary collaterals in patients with CTO. Elder age, women, diabetes, increased plasma level of high-sensitivity C-reactive protein, and N-terminal brain-type natriuretic peptide may be risk factors of CXCR4 expression.

Total Mechanical Unloading Minimizes Metabolic Demand of Left Ventricle and Dramatically Reduces Infarct Size in Myocardial Infarction

Background

Left ventricular assist device (LVAD) mechanically unloads the left ventricle (LV). Theoretical analysis indicates that partial LVAD support (p-LVAD), where LV remains ejecting, reduces LV preload while increases afterload resulting from the elevation of total cardiac output and mean aortic pressure, and consequently does not markedly decrease myocardial oxygen consumption (MVO₂). In contrast, total LVAD support (t-LVAD), where LV no longer ejects, markedly decreases LV preload volume and afterload pressure, thereby strikingly reduces MVO₂. Since an imbalance in oxygen supply and demand is the fundamental pathophysiology of myocardial infarction (MI), we hypothesized that t-LVAD minimizes MVO₂ and reduces infarct size in MI. The purpose of this study was to evaluate the differential impact of the support level of LVAD on MVO₂ and infarct size in a canine model of ischemia-reperfusion.

Methods

In 5 normal mongrel dogs, we examined the impact of LVAD on MVO₂ at 3 support levels: Control (no LVAD support), p-LVAD and t-LVAD. In another 16 dogs, ischemia was induced by occluding major branches of the left anterior descending coronary artery (90 min) followed by reperfusion (300 min). We activated LVAD from the beginning of ischemia until 300 min of reperfusion, and compared the infarct size among 3 different levels of LVAD support.

Results

t-LVAD markedly reduced MVO₂ (% reduction against Control: -56 ± 9%, p<0.01) whereas p-LVAD did less (-21 ± 14%, p<0.05). t-LVAD markedly reduced infarct size compared to p-LVAD (infarct area/area at risk: Control; 41.8 ± 6.4, p-LVAD; 29.1 ± 5.6 and t-LVAD; 5.0 ± 3.1%, p<0.01). Changes in creatine kinase-MB paralleled those in infarct size.

Conclusions

Total LVAD support that minimizes metabolic demand maximizes the benefit of LVAD in the treatment of acute myocardial infarction.

Association of blood pressure and coronary collateralization in type 2 diabetic and nondiabetic patients with stable angina and chronic total occlusion

OBJECTIVE

We investigated whether and to what extent blood pressure (BP) affects coronary collateralization in type 2 diabetic and nondiabetic patients with stable angina and chronic total occlusion.

METHODS

Brachial BP was measured using an inflatable cuff manometer in 431 diabetic and 287 nondiabetic patients with stable angina and angiographic total occlusion of at least one major coronary artery. They were classified according to the SBP (<100, 100-119, 120-139, 140-159, 160-179, and ≥180 mmHg), DBP (<60, 60-69, 70-79, 80-89, 90-99, and ≥100 mmHg), and pulse (<40, 40-49, 50-59, 60-69, 70-79, and ≥80 mmHg) BP ranges. The degree of coronary collaterals supplying the distal aspect of a total occlusion from the contralateral vessel was graded as poor (Rentrop score of 0 or 1) or good collateralization (Rentrop score of 2 or 3).

RESULTS

In diabetic patients, the incidence of poor collateralization was related to the DBP in a U-shaped pattern, with the lowest risk at 80-89 mmHg. In nondiabetic patients, an optimal DBP range was 90-99 mmHg for good collaterals, but no U-shaped relation between DBP and coronary collateralization was observed. After adjusting for the baseline characteristics in the logistic regression models, the increased risk of poor collateralization persisted for low or high DBP ranges in diabetic [odds ratio (OR) 2.02-7.29, P ≤ 0.04] and nondiabetic patients (OR 3.62-5.98, P ≤ 0.02). No such relations were observed between collateral grades and SBP and pulse BP.

CONCLUSION

This study demonstrates that 80-89 and 90-99 mmHg are the optimal ranges for DBP in diabetic and nondiabetic patients with stable angina and chronic total occlusion, within which the risk of poor collateralization is low.

Effect of antihypertensive treatment at different blood pressure levels in patients with diabetes mellitus: systematic review and meta-analyses

OBJECTIVE

To assess the effect of antihypertensive treatment on mortality and cardiovascular morbidity in people with diabetes mellitus, at different blood pressure levels.

DESIGN

Systematic review and meta-analyses of randomised controlled trials.

DATA SOURCES

CENTRAL, Medline, Embase, and BIOSIS were searched using highly sensitive search strategies. When data required according to the protocol were missing but trials were potentially eligible, we contacted researchers, pharmaceutical companies, and authorities.

ELIGIBILITY CRITERIA

Randomised controlled trials including 100 or more people with diabetes mellitus, treated for 12 months or more, comparing any antihypertensive agent against placebo, two agents against one, or different blood pressure targets.

RESULTS

49 trials, including 73,738 participants, were included in the meta-analyses. Most of the participants had type 2 diabetes. If baseline systolic blood pressure was greater than 150 mm Hg, antihypertensive treatment reduced the risk of all cause mortality (relative risk 0.89, 95% confidence interval 0.80 to 0.99), cardiovascular mortality (0.75, 0.57 to 0.99), myocardial infarction (0.74, 0.63 to 0.87), stroke (0.77, 0.65 to 0.91), and end stage renal disease (0.82, 0.71 to 0.94). If baseline systolic blood pressure was 140-150 mm Hg, additional treatment reduced the risk of all cause mortality (0.87, 0.78 to 0.98), myocardial infarction (0.84, 0.76 to 0.93), and heart failure (0.80, 0.66 to 0.97). If baseline systolic blood pressure was less than 140 mm Hg, however, further treatment increased the risk of cardiovascular mortality (1.15, 1.00 to 1.32), with a tendency towards an increased risk of all cause mortality (1.05, 0.95 to 1.16). Metaregression analyses showed a worse treatment effect with lower baseline systolic blood pressures for cardiovascular mortality (1.15, 1.03 to 1.29 for each 10 mm Hg lower systolic blood pressure) and myocardial infarction (1.12, 1.03 to 1.22 for each 10 mm Hg lower systolic blood pressure). Patterns were similar for attained systolic blood pressure.

CONCLUSIONS

Antihypertensive treatment reduces the risk of mortality and cardiovascular morbidity in people with diabetes mellitus and a systolic blood pressure more than 140 mm Hg. If systolic blood pressure is less than 140 mm Hg, however, further treatment is associated with an increased risk of cardiovascular death, with no observed benefit.

Clinical and angiographic features associated with coronary collateralization in stable angina patients with chronic total occlusion

OBJECTIVE

Coronary collateral circulation is an alternative source of blood supply to myocardium in the presence of advanced coronary artery disease. We sought to determine which clinical and angiographic variables are associated with collateral development in patients with stable angina and chronic total coronary occlusion.

METHODS

Demographic variables, biochemical measurements, and angiographic findings were collected from 478 patients with stable angina and chronic total coronary occlusion. The presence and extent of collaterals supplying the distal aspect of a total coronary occlusion from the contra-lateral vessel were graded from 0 to 3 according to the Rentrop scoring system.

RESULTS

Low (Rentrop score of 0 or 1) and high (Rentrop score of 2 or 3) coronary collateralizations were detected in 186 and 292 patients, respectively. Despite similar age, cigarette smoking, and medical treatment, patients with low collateralization were female in a higher proportion and less hypertensive, and had higher rates of type 2 diabetes and dyslipidemia than those with high collateralization (for all comparisons, P<0.05). In addition, patients with low collateralization exhibited more single-vessel disease, less right coronary artery occlusion, more impaired renal function, and higher serum levels of high-sensitivity C-reactive protein (hsCRP) compared with those with high collateralization. Multivariate analysis revealed that age of ≥65 years, female gender, diabetes, no history of hypertension, dyslipidemia, moderate to severe renal dysfunction, single-vessel disease, and elevated hsCRP levels were independently associated with low coronary collateralization.

CONCLUSIONS

Coronary collateralization was reduced in almost 40% of stable angina patients with chronic total occlusion, which was related to clinical and angiographic factors. The impact of coronary collateralization on outcomes after revascularization needs further investigation.