ULnar Artery Transient Compression Facilitating Radial Artery Patent Hemostasis (ULTRA): A Novel Technique to Reduce Radial Artery Occlusion After Transradial Coronary Catheterization

AIMS

To evaluate the safety and efficacy of a novel technique with simultaneous compression of the ulnar artery in order to reduce the incidence of radial artery occlusion (RAO) after transradial cardiac catheterizations.

METHODS AND RESULTS

Ipsilateral ulnar artery transient compression for 1 hour facilitating radial artery patent hemostasis (ULTRA) was performed in all patients treated transradially in October 2015 and was compared with patients treated with conventional patent hemostasis in September 2015. The primary endpoint of the study was to evaluate the incidence of RAO within 1 hour after removing the closure device, confirmed by the absence of palpation and the consecutive absence of flow signal with Doppler examination. A total of 119 patients were treated with the ULTRA method and 121 patients with conventional patent hemostasis. None of the patients treated with ULTRA had RAO compared with 6 patients (5%) of those treated with conventional patent hemostasis (P=.01). No hematomas EASY class ≥3, nerve injury, or ischemic pain complications were recorded in either group.

CONCLUSION

The ULTRA technique may reduce the incidence of RAO in patients treated with the radial approach compared with conventional patent hemostasis.

Local conduction during acute myocardial infarction in rats: Interplay between central sympathetic activation and endothelin

We investigated the effects of autonomic dysfunction and endothelin on local conduction and arrhythmogenesis during myocardial infarction. We recorded ventricular tachyarrhythmias, monophasic action potentials, and activation sequences in wild-type and ET_B-deficient rats displaying high endothelin levels. Central sympathetic inputs were examined after clonidine administration. Clonidine mitigated early and delayed arrhythmogenesis in ET_B-deficient and wild-type rats, respectively. The right ventricular activation delay increased in clonidine-treated ET_B-deficient rats and slightly decreased in wild-type rats. The left ventricular voltage rise decreased in all groups, whereas the activation delay increased mainly in clonidine-treated ET_B-deficient rats. Central sympathetic activation and endothelin modulate ischemia-induced arrhythmogenesis. Ischemia alters excitability, whereas endothelin impairs local conduction, an action partly counterbalanced by central sympathetic activity.

Transradial Approach for Cardiac Catheterization in Patients With Negative Allen's Test

AIMS

To assess the efficacy and safety of transradial approach regardless of the Allen's test results for coronary angiography and angioplasty.

METHODS AND RESULTS

Prospective data collection of 1035 consecutive patients who underwent coronary angiography with or without ad hoc angioplasty through the radial approach was conducted. Baseline demographic and procedural data were recorded. Allen's test was evaluated in all subjects before the procedure and catheterization was performed from the radial approach irrespective of the results. Radial artery patency was evaluated at discharge clinically, or by Doppler examination if pulse was not palpable. A total of 256 patients (24.7%) were found to have a negative Allen's test and 779 patients (75.3%) had a positive test. The baseline and procedural characteristics were similar in both groups. No significant differences in complications were reported. Radial artery thrombosis was observed in 6.2% of the negative Allen's test group and 4.8% of the positive Allen's test group (P=.85), but this was clinically silent even in the negative Allen's test group.

CONCLUSION

Transradial approach for coronary angiography and ad hoc angioplasty can be performed with similar efficacy and safety regardless of the Allen's test results before the procedure.

Central Sympathetic Activation and Arrhythmogenesis during Acute Myocardial Infarction: Modulating Effects of Endothelin-B Receptors

Sympathetic activation during acute myocardial infarction (MI) is an important arrhythmogenic mechanism, but the role of central autonomic inputs and their modulating factors remain unclear. Using the in vivo rat-model, we examined the effects of clonidine, a centrally acting sympatholytic agent, in the presence or absence of myocardial endothelin-B (ETB) receptors. We studied wild-type (n = 20) and ETB-deficient rats (n = 20) after permanent coronary ligation, with or without pretreatment with clonidine. Cardiac rhythm was continuously recorded for 24 h by implantable telemetry devices, coupled by the assessment of autonomic and heart failure indices. Sympathetic activation and arrhythmogenesis were more prominent in ETB-deficient rats during the early phase post-ligation. Clonidine improved these outcomes throughout the observation period in ETB-deficient rats, but only during the delayed phase in wild-type rats. However, this benefit was counterbalanced by atrioventricular conduction abnormalities and by higher incidence of heart failure, the latter particularly evident in ETB-deficient rats. Myocardial ETB-receptors attenuate the arrhythmogenic effects of central sympathetic activation during acute MI. ETB-receptor deficiency potentiates the sympatholytic effects of clonidine and aggravates heart failure. The interaction between endothelin and sympathetic responses during myocardial ischemia/infarction and its impact on arrhythmogenesis and left ventricular dysfunction merits further investigation.

Arrhythmogenesis after acute myocardial necrosis with and without preceding ischemia in rats

BACKGROUND

The relative role of acute myocardial ischemia and infarction in ventricular arrhythmogenesis is incompletely understood. We compared the arrhythmia pattern after ischemia/infarction to that observed after direct myocardial necrosis without preceding ischemia in rats.

METHODS

Coagulation necrosis was induced in Wistar rats (n=20, 280±3 g) by radiofrequency current application (for 15 s) from a 4-mm-tip ablation catheter. Myocardial infarction was induced by coronary artery ligation with (n=10) or without (n=10) reperfusion. Using 24-h telemetry recording, we examined ventricular arrhythmias, voluntary motor activity and indices of sympathetic activation.

RESULTS

The coagulation-necrosis volume was 24.4%±0.6%, comparable to the infarct size in the absence of reperfusion. Acute left ventricular failure and sympathetic activation were similar in the three groups. Coagulation necrosis induced ventricular fibrillation immediately, followed by a second peak after ∼1 h. Reperfusion decreased ventricular arrhythmias, whereas a second arrhythmogenic period (between the third and the eight hour) was noted in non-reperfused infarcts (mainly monomorphic ventricular tachycardia).

CONCLUSIONS

Distinct arrhythmia patterns occur after myocardial infarction (with or without reperfusion) and after direct necrosis. They are not produced by differences in sympathetic activation and are likely related to the evolution of myocardial injury. The necrosis rat model may be useful in studies of arrhythmogenesis.

Endothelin B-receptors and sympathetic activation: impact on ventricular arrhythmogenesis during acute myocardial infarction

AIMS

We investigated the role of endothelin-B receptors on sympathetic activation originating from the adrenal gland or from the myocardium and its impact on arrhythmogenesis during acute myocardial infarction.

MAIN METHODS

We studied two groups of rats (n=120, 284±2 g), namely wild-type and ETB-deficient. Myocardial infarction was induced by permanent ligation of the left coronary artery and ventricular tachyarrhythmias were evaluated from continuous electrocardiographic recordings. Sympathetic activation, measured by indices of heart rate variability, was evaluated after adrenalectomy or catecholamine depletion induced by reserpine. Acute left ventricular failure was assessed by total animal activity.

KEY FINDINGS

Adrenalectomy decreased the total duration of tachyarrhythmias in ETB-deficient rats, but their incidence remained higher, compared to wild-type rats. After reserpine, heart rate variability indices and tachyarrhythmias were similar in the two groups during the initial, ischaemic phase. During evolving infarction, tachyarrhythmia duration was longer in ETB-deficient rats, despite lower sympathetic activation. Heart rate was lower in ETB-deficient rats throughout the 24-hour observation period, whereas activity was comparable in the two groups.

SIGNIFICANCE

Endothelin-B receptors modulate sympathetic activation during acute myocardial infarction not only in the ventricular myocardium, but also in the adrenal gland. Sympathetic activation markedly increases early-phase ventricular tachyarrhythmias, but other mechanisms involving the endothelin system underlie delayed arrhythmogenesis.

Myocardial Protection Provided by Chronic Skeletal Muscle Ischemia Is Not Further Enhanced by Ischemic Pre- or Postconditioning

Chronic skeletal muscle ischemia protects the ischemic heart by preserving coronary flow and inducing arterioangiogenesis. We sought to determine the effect and the underlying molecular mechanisms of preconditioning (PreC) and postconditioning (PostC), applied in a model of chronic skeletal muscle ischemia. Male rabbits were divided into 3 series. In each series, the animals were subjected either to severe hind limb (HL) ischemia, by excision of the femoral artery, or to sham operation (SHO). After 4 weeks, all the animals underwent 30 minutes of regional heart ischemia and 3 hours reperfusion. The animals of the first series received no further intervention (HL and SHO groups), those of the second series underwent PreC (HL + PreC and SHO + PreC), and of the third series PostC (HL + PostC and SHO + PostC). Infarct size (I) and risk zones (R) were determined, and their ratio was calculated in percentage. Three additional series of experiments were performed with respective interventions up to the 10th minute of reperfusion, where sample tissue was obtained for assessment of protein kinase B (Akt), endothelial nitric oxide synthase (eNOS), glycogen synthase kinase 3β (GSK3β), p44/42, signal transducer and activator of transcription (STAT) 3, and STAT5. All groups demonstrated significantly smaller percentage of I/R compared with the SHO group (HL: 14.4% ± 3.7%, HL + PreC: 13.1% ± 1.0%, SHO + PreC: 21.3% ± 1.6%, HL + PostC: 18.0% ± 1.1%, and SHO + PostC: 24.3% ± 1.7%, P < .05 vs 35.7% ± 4.4% in SHO). The PreC and PostC did not further reduce the infarct size in HL groups. The Akt, eNOS, GSK3β, p44/42, and STAT3 were activated in all PreC or PostC groups regardless of the infarct size reduction. The STAT5 was activated only in the HL groups compared with the SHO groups. In conclusion, chronic skeletal muscle ischemia results in effective cardioprotection, which is not further enhanced with application of PreC or PostC. The Akt, eNOS, GSK3β, p44/42, and STAT3 may only be considered as indicators of the intracellular changes taking place during protection. Activation of STAT5 is possibly the end effector, which is responsible for infarct size reduction provided by chronic skeletal muscle ischemia.

Chronic skeletal muscle ischemia preserves coronary flow in the ischemic rat heart

Chronic skeletal muscle ischemia confers cytoprotection to the ventricular myocardium during infarction, but the underlying mechanisms remain unclear. Although neovascularization in the left ventricular myocardium has been proposed as a possible mechanism, the functional capacity of such vessels has not been studied. We examined the effects of chronic limb ischemia on infarct size, coronary blood flow, and left ventricular function after ischemia-reperfusion. Hindlimb ischemia was induced in 65 Wistar rats by excision of the left femoral artery, whereas 65 rats were sham operated. After 4 wk, myocardial infarction was generated by permanent coronary artery ligation. Infarct size was measured 24 h postligation. Left ventricular function was evaluated in isolated hearts after ischemia-reperfusion, 4 wk after limb ischemia. Neovascularization was assessed by immunohistochemistry, and coronary flow was measured under maximum vasodilatation at different perfusion pressures before and after coronary ligation. Infarct size was smaller after limb ischemia compared with controls (24.4 ± 8.1% vs. 46.2 ± 9.5% of the ventricle and 47.6 ± 8.7% vs. 80.1 ± 9.3% of the ischemic area, respectively). Indexes of left ventricular function at the end of reperfusion (divided by baseline values) were improved after limb ischemia (developed pressure: 0.68 ± 0.06 vs. 0.59 ± 0.05, P = 0.008; maximum +dP/d t: 0.70 ± 0.08 vs. 0.59 ± 0.04, P = 0.004; and maximum −dP/d t: 0.86 ± 0.14 vs. 0.72 ± 0.10, P = 0.041). Coronary vessel density was markedly higher ( P = 0.00021) in limb ischemic rats. In contrast to controls ( F = 5.65, P = 0.00182), where coronary flow decreased, it remained unchanged ( F = 1.36, P = 0.28) after ligation in limb ischemic rats. In conclusion, chronic hindlimb ischemia decreases infarct size and attenuates left ventricular dysfunction by increasing coronary collateral vessel density and blood flow.

Chronic skeletal muscle ischemia in rats decreases the inducibility of ventricular tachyarrhythmias after myocardial infarction

BACKGROUND

Chronic hind-limb ischemia confers cytoprotection after coronary occlusion, but it is unclear whether it ameliorates substrate formation for ventricular tachyarrhythmias (VTs).

MATERIALS AND METHODS

Chronic hind-limb ischemia was generated by femoral artery excision in 50 rats, while 25 animals were sham-operated. Left coronary artery ligation was performed after 3 weeks and infarct size was measured 24 hours thereafter. The inducibility of VTs was assessed by programmed electrical stimulation (PES) 4 weeks post-ligation. A score was assigned, based on protocol stage and tachyarrhythmia duration. Monophasic action potentials (MAP) were recorded prior to and 4 weeks after ligation.

RESULTS

The infarct size was smaller (p=0.000079) in the ischemic rats (25.7±2.1%) than in the controls (41.7±2.2%), accompanied by a lower (p=0.029) arrhythmia score (1.05±0.38 versus 2.70±0.68, respectively). The action potential duration (APD) was shorter (p<0.05) in the ischemic rats prior to ligation and remained stable after 4 weeks.

CONCLUSION

Chronic hind limb ischemia limits infarct size and decreases inducible ventricular tachyarrhythmias.

Likelihood of Brugada ECG pattern confirmed after propafenone administration for atrial fibrillation cardioversion

It has been reported that Brugada syndrome is responsible for about half of the sudden cardiac death events with no evidence of structural heart disease. We report a case of hidden ECG Brugada pattern, revealed after oral propafenone administration in the setting of pharmaceutical atrial fibrillation cardioversion.

Dose-dependent effects of sildenafil on post-ischaemic left ventricular function in the rat isolated heart

Objectives

Sildenafil may be beneficial during myocardial ischaemia/reperfusion, but this effect may be dose-dependent, accounting for previous conflicting results. We have explored the effects of two acute and one chronic administration regimen on left ventricular function.

Methods

The study was conducted on 36 Wistar rats (290 ± 7 g). Sildenafil was administered 30 min before ischaemia at a low (0.7 mg/kg, n= 8) or high (1.4 mg/kg, n= 8)dosage. The chronic treatment arm (n= 8) consisted of two daily injections of sildenafil (0.7 mg/kg) for three weeks. The control group was formed by 12 rats. Ischaemic contracture, post-ischaemic recovery and hypercontracture were measured in isolated, Langendorff-perfused preparations.

Key findings

Ischaemic contracture tended to be lower after high-dose sildenafil, while remaining unchanged after low-dose or chronic sildenafil administration. Compared with controls (62.9 ± 2.0% of baseline developed pressure), post-ischaemic recovery was higher (P= 0.0069) after low dose (75.1 ± 2.4%), unchanged (P= 0.13) after high dose (69.1 ± 2.1%), but lower (P &lt; 0.001) after chronic (42.9 ± 4.5%) sildenafil administration. Compared with controls (71.8 ± 3.9 mmHg), hypercontracture was higher (P= 0.0052) after chronic sildenafil administration (89.5 ± 4.1 mmHg), but similar after acute low dose (65.7 ± 3.3 mmHg, P= 0.33) or high dose (67.1 ± 4.7 mmHg, P= 0.43).

Conclusions

The effects of sildenafil after ischaemia/reperfusion were strongly dose-dependent. Beneficial actions on left ventricular function were evident after acute pretreatment with a low dosage, but were lost after doubling the dose. Chronic sildenafil administration deteriorated left ventricular function during ischaemia and reperfusion.

Chronic hind limb ischemia reduces myocardial ischemia-reperfusion injury in the rabbit heart by promoting coronary angiogenesis/arteriogenesis

BACKGROUND/AIM

Application of ischemic injury in a remote organ may provide protection of other tissues against ischemia. We hypothesized that ischemia in the rabbit hind limb protects against myocardial ischemia by increasing angiogenesis/arteriogenesis.

MATERIALS AND METHODS

In the first experiment, severe limb ischemia (LI) was induced in 26 New Zealand White rabbits by excision of the femoral artery while another 26 served as controls (no ischemia; sham operation [SHO]). Four weeks later, the blood vessels of the subendocardial and intramyocardial areas of the excised hearts were counted. In the second experiment, 14 LI rabbits and 14 SHO controls were subjected to 30 min of regional heart ischemia and 3 h reperfusion. Infarct size and the areas-at-risk were determined.

RESULTS

Compared with controls, LI rabbits showed more subendocardial (103+/-14 vs. 113+/-13 capillaries/mm2, respectively; p=0.01) and intramyocardial blood vessels (102+/-12 vs. 114+/-16 capillaries/mm(2), respectively; p=0.009). LI rabbits had significantly smaller infarct size compared with the SHO animals (infarct areas/areas-at-risk: 14.37+/-11.23% vs. 31.31+/-13.73%, respectively; p=0.003).

CONCLUSION

Chronic hind LI reduces myocardial infarct size by promoting coronary angiogenesis/arteriogenesis in an experimental model.

Evaluation of aortic stiffness (aortic pulse-wave velocity) before and after elective abdominal aortic aneurysm repair procedures: a pilot study

Background:

The main clinical criterion for abdominal aortic aneurysm (AAA) repair operations is an AAA diameter ≥5.5 cm. When AAAs increase in size, specific changes occur in the mechanical properties of the aortic wall. Pulse-wave velocity (PWV) has been used as an indicator of vascular stiffness. A low PWV may predict AAA rupture risk and is an early predictor of cardiovascular mortality.

Methods:

We investigated the prognostic value of PWV before and after elective AAA repair procedures. Twenty four patients scheduled for an open AAA repair underwent a preoperative carotid-femoral aortic PWV measurement. A second aortic PWV measurement was carried out 6 months postoperatively.

Results:

The mean aortic PWV increased from 7.84 ± 1.85 preoperatively to 10.08 ± 1.57 m/sec 6 months postoperatively (mean change: 2.25; 95% confidence interval 1.4 to 3.1 m/sec; p<0.0001). The preprocedural PWV measurement did not correlate with AAA diameter (Spearman’s rank correlation coefficient ρ=0.12; p=0.59).

Conclusions:

Whether the increase in aortic PWV postoperatively suggests a decreased cardiovascular risk following AAA repair remains to be established. Aortic PWV should also be investigated as an adjunct tool for assessing AAA rupture risk.

Serum leptin levels in patients undergoing carotid endarterectomy: a pilot study

INTRODUCTION

Elevated serum leptin levels are associated with cardiovascular events. We investigated the role of serum leptin in patients undergoing carotid endarterectomy (CEA).

METHODS

A total of 74 patients (55 men; 38 symptomatic and 36 asymptomatic; mean age 66.9 +/- 8.2 years) undergoing CEA for >70% carotid artery stenosis were enrolled.

RESULTS

Serum leptin levels were lower in symptomatic compared with asymptomatic patients (7.1 +/- 1.3 vs 14.4 +/- 4.7 ng/dL; P < .001). Interleukin-6 (IL-6) levels were higher in symptomatic compared with asymptomatic patients (4.3 +/- 1.7 vs 3.3 +/- 1.1 pg/dL; P = .017). Symptomatic patients had more intense macrophage accumulation (0.7% +/- 0.1% vs 0.3% +/- 0.1%; P < .001). Serum leptin and serum IL-6 levels were independently associated with the presence of symptoms in multivariate analysis.

CONCLUSION

Serum leptin levels were decreased in symptomatic carotid artery disease. This finding requires further investigation in larger studies.

Treatment of a coronary artery aneurysm with a novel stent

We report a case of a prominent aneurysm of the right coronary artery secondary to atherosclerotic coronary artery disease. The aneurysm was complicated by recurrent myocardial infarction despite optimal medical treatment. It was successfully treated with coronary artery stenting, using a novel device, consisting two stents with a layer of expandable graft material placed between them. Follow-up angiography 6 months after the procedure showed a sustained excellent result.

Brain natriuretic peptide increases acutely and much more prominently than atrial natriuretic peptide during coronary angioplasty

BACKGROUND

Increased levels of plasma brain natriuretic peptide (BNP) are observed in patients with congestive heart failure, hypertension, left ventricular hypertrophy, and acute myocardial infarction. However, there are no data on serial changes in plasma levels of BNP in patients undergoing coronary angioplasty.

HYPOTHESIS

The study was undertaken to examine plasma concentrations of BNP together with those of atrial natriuretic peptide (ANP) in patients undergoing percutaneous transluminal coronary angioplasty (PTCA).

METHODS

Plasma concentrations of BNP and ANP were examined in 13 patients with stable angina pectoris and good left ventricular function undergoing PTCA. Blood samples were taken from the femoral vein at baseline, after the first balloon inflation, after the end of the procedure, and 4 h thereafter.

RESULTS

Plasma BNP levels were 14 +/- 4 at baseline, 22 +/- 10 after the first balloon inflation, 28 +/- 12 at the end of the procedure, and 15 +/- 4 pgr/ml 4 h thereafter (F = 13.05, p < 0.00001). Plasma ANP levels were 80 +/- 15, 86 +/- 14, 90 +/- 24, and 75 +/- 6 fmol/l (F = 5.95, p = 0.002), respectively. The increase of BNP at the end of the procedure was related to the increase of ANP (r = 0.78, p = 0.002).

CONCLUSION

Plasma BNP levels increase acutely and much more prominently than those of plasma ANP during coronary angioplasty; however, plasma BNP levels return to baseline values shortly after the end of the procedure.

Atrial natriuretic peptide augments coronary collateral blood flow: a study during coronary angioplasty

BACKGROUND AND HYPOTHESIS

In vitro studies have shown that atrial natriuretic peptide (ANP) causes relaxation of preconstricted blood vessel strips and inhibits the contraction of isolated vessels in response to norepinephrine and angiotensin II. The present study examined the effects of exogenous ANP on the coronary collateral blood flow during angioplasty.

METHODS

We studied 15 patients undergoing elective balloon angioplasty during the second and third balloon inflations. A Doppler flow guidewire was advanced distal to the lesion and used for the estimation of coronary blood flow velocity. After the second balloon inflation, 25 ng/kg/min of ANP were administered intracoronarily for 8 min. Electrocardiogram, pressure, and flow velocity were recorded immediately before each balloon deflation. Fourteen other patients served as controls and received normal saline infusion.

RESULTS

Velocity time integral increased from 65 +/- 40 to 79 +/- 46 mm (p < 0.05) during the third balloon inflation, whereas ST deviation decreased from 1.3 +/- 0.9 to 0.7 +/- 1.0 mV (p < 0.05). These variables did not change in the control group during the two tested balloon inflations.

CONCLUSION

Exogenous ANP augments coronary collateral blood flow and ameliorates myocardial ischemia during angioplasty.

Serum interleukin-6 is elevated in symptomatic carotid bifurcation disease

INTRODUCTION

The levels of circulating proinflammatory cytokines may express the extent of the inflammatory response and their participation in plaque progression and rupture needs to be evaluated. We aimed to investigate differences in circulating levels of proinflammatory cytokines and in plaque infiltration by macrophages between patients undergoing carotid endarterectomy for symptomatic and asymptomatic carotid atherosclerotic disease.

METHODS

One hundred nineteen patients (91 men and 28 women; mean age 66 +/- 8 years; range 42-83 years) who underwent carotid endarterectomy for significant (>70%) carotid bifurcation stenosis were enrolled in this study. Patients were characterized as symptomatic (n = 62) or asymptomatic (n = 57) after neurological examination. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, serum amyloid A (SAA), and high-sensitivity C-reactive protein (hs-CRP) were evaluated. Macrophage infiltration of the plaque was assessed quantitatively from endarterectomy specimens using the monoclonal antibody CD68.

RESULTS

Serum IL-6 levels were significantly higher in patients with symptomatic compared with those with asymptomatic carotid disease (3.3 [2.0-6.5] pg/ml vs 2.5 [1.9-4.1] pg/ml, P = 0.02). TNF-alpha, IL-1beta, SAA, and hs-CRP levels did not differ significantly between the two groups. Symptomatic patients had also more intense macrophage accumulation in the carotid plaque compared with asymptomatic patients (0.6 +/- 0.1% vs 0.4 +/- 0.1%, P < 0.001). Although there were correlations between the levels of the different inflammatory markers, there were no correlation between any of them and the extent of plaque macrophage infiltration.

CONCLUSION

Patients with symptomatic carotid atherosclerotic disease have elevated serum IL-6 levels compared with asymptomatic patients. Symptomatic patients have also more intense macrophage infiltration of the atherosclerotic plaque suggesting that inflammatory process may contribute to the destabilization of the carotid plaque.

Systemic hypertension augments, whereas insulin-dependent diabetes down-regulates, endothelin A receptor expression in the mammary artery in coronary artery disease patients

BACKGROUND

Endothelin (ET) A receptor antagonism causes decreased vasodilation in hypertensive coronary arteries and decreased effects on coronary artery compliance in diabetic patients.

METHODS

We investigate the mRNA expression of ET-1, ET(A) and ET(B) receptors, using real time RT-PCR, in biopsies from the internal mammary artery obtained from 49 patients, 18 diabetics and 34 hypertensives, all undergoing coronary artery bypass grafting.

RESULTS

Hypertensive patients had higher ET-1 mRNA expression (16438 [8417, 23917]), than normotensive patients (2974 [2283, 18055], p=0.008). Diabetic patients had significantly lower ET(A) receptor levels than non-diabetic patients (455 [167, 1496] vs. 1660 [700, 3190], respectively, p = 0.003).

CONCLUSIONS

Multivariate analysis demonstrated that the presence of systemic hypertension was the only independent predictor of log ET(A) receptor expression and log ET-1 expression, while insulin-dependent diabetes was negatively correlated with ET(A) receptor expression. ETB receptor expression was not correlated with any predictor. Systemic hypertension is associated with increased ET-1 and ET(A) receptor mRNA expression, whereas insulin-dependent diabetes down-regulates ET(A) receptor mRNA expression in the internal mammary artery in patients with coronary artery disease undergoing bypass grafting.

Statin treatment, carotid atherosclerotic plaque macrophage infiltration and circulating inflammatory markers

BACKGROUND

Statin treatment is considered as first line therapy in patients with atherosclerotic disease. We evaluated the effect of pre-treatment with statins on carotid plaque infiltration by macrophages and on the circulating levels of proinflammatory cytokines in patients who underwent carotid endarterectomy.

PATIENTS AND METHODS

One hundred fourteen patients were enrolled; 89 men and 25 women (mean age 67+/-8 years; range 42-83 years). Fifty three patients (46%) were on statin treatment at least 3 months before endarterectomy and 61 (54%) had never received statin treatment. The serum levels of high sensitivity C reactive protein (hsCRP), serum amyloid A (SAA), tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta and IL-6 were evaluated preoperatively. The intensity of macrophage infiltration was evaluated by immunochemistry, using the monoclonal antibody CD 68. The area of the plaque covered by macrophages was measured as a proportion of the whole plaque area, using a custom designed image tool analysis.

RESULTS

Patients on statins had lower serum total cholesterol levels (172+/-50 vs 194+/-35 mg/dl, p= 0.014), lower low density cholesterol levels (103+/-44 vs 123+/-31 mg/dl, p= 0.010) and lower serum hsCRP levels (1.8 [1.1-3.4] vs 3.4 [1.3-4.9] mg/l, p= 0.03), while SAA, TNFalpha, IL-6 and IL-1beta levels did not differ between the 2 groups. The infiltration of atherosclerotic plaque by macrophages was similar in statin treated patients and in controls (0.55+/-0.15% vs 0.49+/-0.19%, p= 0.21).

CONCLUSION

Patients on statins have similar macrophage accumulation in their carotid atherosclerotic plaques compared with patients not on statins. Inflammatory markers were also similar in both groups except for hsCRP which was significantly lower in those taking statins.

Isolated right ventricular infarction presenting with ST-segment elevation in precordial leads V1-V3

We describe a rare case of a patient presenting with ST-segment elevation in precordial leads V1-V3 due to occlusion of the ventricular branch of the right coronary artery during primary percutaneous coronary angioplasty.

Restenosis is not associated with stent length in a pig model of coronary stent implantation

BACKGROUND

The aim of this study was to determine if stent length is by itself a risk factor for intimal proliferation and restenosis. Long lesions represent an independent risk factor for restenosis after coronary stent implantation. A longer stented segment might result in a higher probability of restenosis.

METHODS

Twenty-two 7-month-old male farm pigs underwent implantation of two steel stents, one short (8 mm length) and one long (16 mm length), in the right coronary artery. The pigs were sacrificed 28 days after stent implantation and histomorphometric analysis of the coronary arteries was performed for neointimal area proliferation and area stenosis evaluation.

RESULTS

Seventeen short stents and 19 long stents were finally implanted. There were no differences in neointimal proliferation (1.84 +/- 0.64 mm2 vs. 1.81 +/- 0.94 mm2, p = 0.84), area stenosis (40 +/- 9% vs. 41 +/- 19%, p = 0.86) and lumen area (2.96 +/- 1.30 mm2 vs. 2.51 +/- +/- 1.18 mm2, p = 0.21) between the short stent group and the long stent group, respectively.

CONCLUSIONS

These data suggest that stent length by itself does not influence restenosis extent in the porcine model.

Does sildenafil cause myocardial infarction or sudden cardiac death?

Sildenafil was the first oral compound to be approved for the treatment of erectile dysfunction. In this paper, we review the current knowledge of the effects of sildenafil on myocardial infarction and sudden cardiac death. The first factor we examine is the sexual activity itself. As several studies have shown, the relative risk for an acute coronary syndrome during intercourse is not very high. Several studies examining the effects of sildenafil on mortality have been published during recent years. The great majority of these studies found that sildenafil is not an extra risk factor for an acute coronary syndrome or sudden cardiac death. In 1997, the rate of myocardial infarction in men 55-64 years of age was 1542 per 1,000000 in the US. According to this, the expected number of deaths as a result of myocardial infarction in patients 55-64 years of age receiving sildenafil, in the 24-hour period after use, from late March 1997 to mid November 1998, should have been 52. Instead, the number of reported deaths were only 15. One very optimistic finding was that sildenafil not only does not increase mortality, but in fact 'preconditions' the heart and has a cardioprotective effect. Besides, many studies have shown that sildenafil does not reduce the exercise tolerance in men with known coronary artery disease. As far as BP is concerned, the differences before and after the use of sildenafil are not clinically significant. The only contraindications for sildenafil are co-administration with alpha-adrenoceptor antagonists or with nitric oxide donors. According to the most recent studies, isoform 5 of phosphodiesterase has also been detected in the myocardium and controls the soluble pool of 3', 5'-cyclic guanosine monophosphate (cGMP). Sildenafil is very specific for cGMP but it may increase cyclic adenosine monophosphate in the myocardium indirectly. This does not occur with small therapeutic doses of the drug. There is some dispute regarding the association of sildenafil with arrhythmias, where the available evidence is not clear. However, there are suspicions that sildenafil may cause sympathetic activation. The overall conclusion is that sildenafil is a safe drug and that its appropriate use does not seem to increase the risk for myocardial infarction or sudden cardiac death.

Effects of dual endothelin receptor blockade on sympathetic activation and arrhythmogenesis during acute myocardial infarction in rats

The effects of dual (ETA and ETB) endothelin receptor blockade on ventricular arrhythmogenesis during acute myocardial infarction are not well defined. We randomly allocated Wistar rats to bosentan (100 mg/kg daily, n=24), a dual endothelin receptor antagonist, or vehicle (n=23). After 7 days of treatment, myocardial infarction was induced by permanent coronary ligation. Ventricular tachyarrhythmias were evaluated for 24 h following ligation, using a miniature telemetry electrocardiogram recorder. Action potential duration was measured from monophasic epicardial recordings and sympathetic activation was assessed by heart rate variability and catecholamine serum level measurements. Compared to controls (1012+/-185 s), bosentan (59+/-24 s) markedly decreased (P<0.00001) the total duration of ventricular tachyarrhythmias during the delayed (1-24 h) phase post-ligation, with a modest effect during the early (0-1 h) phase (132+/-38 s, versus 43+/-18 s, respectively, P=0.053). Treatment did not affect infarct size or total mortality. Action potential duration at 90% repolarization prolonged in controls (from 93.1+/-4.7 ms to 117.6+/-6.9 ms), displaying increased temporal dispersion (from 4.14+/-0.45 ms to 10.42+/-2.51 ms, both P<0.001), but was preserved in treated animals. Bosentan decreased norepinephrine, but increased epinephrine levels 24 h post-ligation. Low frequency spectra of heart rate variability, an index of net sympathetic tone, were lower in bosentan-treated rats. Dual endothelin-1 receptor blockade decreases ventricular tachyarrhythmias during myocardial infarction without reperfusion, by preventing repolarization inhomogeneity. Diverse treatment effects on sympathetic activation may ameliorate the antiarrhythmic action.

Interventional hypothermia and primary percutaneous coronary intervention in a patient with anterior wall ST elevation myocardial infarction and aborted sudden death

We present the case of a 38-year-old man who was successfully treated with interventional hypothermia and primary percutaneous coronary intervention after cardiac arrest and prolonged resuscitation, following an ST-segment elevation myocardial infarction.

Cardiac troponin I in patients with acute lower limb ischemia

The presence, cause, and clinical significance of elevated cardiac troponin I in patients with acute lower limb ischemia is yet unknown. Forty-six patients (20 men [43%]; mean age 72 +/- 10 years, range 42 to 92) with acute lower limb ischemia were enrolled in this study. Serial creatine kinase (CK), CK isoenzyme MB (CK-MB), and troponin I measurements were obtained in all consecutive patients. Peak levels were evaluated for each patient. Twenty-four patients (52%) had elevated peak troponin I levels (>0.2 ng/ml) during their hospitalization. Patients were divided into 3 groups according to their peak troponin I levels: 11 patients (24%) had peak troponin I levels >1 ng/ml (the high troponin I group), 13 (28%) had levels of 0.2 to 1 ng/ml (the intermediate troponin I group), and the remaining 22 (48%) had peak troponin I levels <0.2 ng/ml (the low troponin I group). The peak CK levels were 10,263 +/- 16,513, 1,294 +/- 1,512, and 934 +/- 1,045 IU/ml (p = 0.04) in the 3 different troponin I subgroups, respectively, and the peak CK-MB levels were 143 +/- 170, 38 +/- 31, and 38 +/- 43, respectively (p = 0.04). Troponin I was positively correlated with CK (R = 0.35, p = 0.017) and CK-MB (R = 0.38, p = 0.009). The mean length of hospitalization was 8.3 +/- 6.2 days for the whole study group and did not vary among the 3 troponin I groups (10.5 +/- 10.9 vs 8.6 +/- 4.9 vs 7.2 +/- 4.0 days, p = 0.762). There were no differences in mortality during hospitalization among the 3 groups (4 of 11 vs 1 of 13 vs 4 of 22 patients, p = 0.22). In conclusion, patients with acute lower limb ischemia often have elevated cardiac troponin I levels. Elevated troponin I levels were not associated with the duration of hospitalization or with in-hospital mortality in this group of patients.

Repeated Balloon Inflations Do Not Diminish ST Segment Elevation even though Coronary Collateral Recruitment Is Promoted in Pigs

OBJECTIVE

Attempts to demonstrate preconditioning during repeated angioplasty balloon inflations (BIs) have not been universally successful. The main obstacle is that the first BI is unreliable, due to the variable degrees of occlusion by the deflated balloon. In the present study, we examined whether ST segment elevation decreases and evaluated its relation to collateral recruitment during repeated angioplasty BIs in the pig.

METHODS AND RESULTS

Twenty male pigs, 7 months old, under general anesthesia, underwent 3 repeated BIs of 120 s, with a 5-min interval between them, in the left anterior descending artery or the right coronary artery. A pressure wave wire was used for the measurement of coronary wedge pressure and to obtain the intracoronary ST segment elevation. Intracoronary ST segment elevation was 1.97 +/- 0.76 mV during the 1st BI, 2.09 +/- 0.82 mV during the 2nd BI and 1.84 +/- 0.82 mV during the 3rd BI (p = n.s.). Coronary wedge pressure was 12 +/- 6, 18 +/- 18 and 20 +/- 20 mm Hg (p < 0.05 vs. 1st BI) during the 3 BIs, respectively.

CONCLUSION

Repeated BIs do not diminish ST segment elevation in the pig model, even though coronary collateral recruitment is promoted.

Very late in-stent restenosis in a bare metal stent

Restenosis after coronary artery stenting is a common phenomenon and represents a topic of great interest. Although a great volume of research is referring to restenosis, still many issues are not fully understood by the cardiological community. Here we present a case of very late restenosis, after a bare metal stent implantation.

Atrial fibrillation induced by carotid sinus massage

A case of atrial fibrillation paroxysm induced by carotid sinus massage is reported in a patient with recurrent episodes of syncope. Despite extensive investigations, no cause for the syncopal episodes was determined.

The effects of ventricular asynchrony on myocardial perfusion

Asynchronous depolarization and contraction sequence, secondary to intraventricular conduction defects or to permanent right ventricular apical pacing, is associated with adverse effects that may be clinically evident in the failing heart. Experimental and clinical studies have suggested that asynchronous ventricular contraction deteriorates left ventricular performance and induces unfavourable left ventricular remodelling. Although such contraction does not appear to affect resting coronary artery blood flow, it increases endomyocardial pressure during diastole and decreases regional myocardial perfusion in the interventricular septum. The magnitude of these effects may correlate with the duration of the asynchrony. Despite these detrimental effects, there is no evidence that ventricular asynchrony reduces collateral myocardial blood flow, myocardial oxygen consumption or cardiac efficiency, neither in patients with normal coronary arteries, nor in patients with coronary artery disease. Furthermore, in patients with acute ischaemic syndromes, ventricular asynchrony exerts a neutral effect on the ischaemic myocardium. Cardiac resynchronization therapy improves left ventricular systolic and diastolic function without an increase in myocardial oxygen consumption or energy cost. This therapy may decrease the inhomogeneity in regional oxidative metabolism, myocardial perfusion and cardiac efficiency. Further experimental and clinical studies are needed on this area.

Brain natriuretic peptide as marker of myocardial iron load in beta-thalassemia

Cardiomyopathy due to iron overload represents a frequent life-limiting complication in patients with beta-thalassemia major. We have conducted a study which proved that brain natriuretic peptide plasma levels have high sensitivity and negative predictive value in detecting cardiac hemosiderosis.

Estrogen decreases neointimal hyperplasia and improves re-endothelialization in pigs

BACKGROUND

17-Beta-estradiol inhibits smooth muscle cell proliferation and migration and accelerates endothelial cell repair in response to balloon injury. The aim of this study was to determine whether administration of estrogen is associated with decreased neointimal hyperplasia after stenting in the porcine model.

METHODS AND RESULTS

Twenty-two farm female pigs 7 months old were oophorectomized and at the third day normal saline (11 pigs) or 20 mg of estradiol valerate (11 pigs), modified release, were administered intramuscularly. At the 10th day after oophorerectomy, 1 or 2 stainless steel stents were implanted in the right coronary artery in each pig, and at the 17th day, normal saline or 10 mg estradiol valerate, modified release, were administered intramuscularly in the two groups. Pigs were sacrificed 28 days after stent implantation and histomorphometric analysis of the coronary arteries was performed (20 stents from the estrogen and 18 stents from the control groups). In the estrogen group, neointimal proliferation area was 1.42+/-0.55 mm(2), whereas in the control group, 1.96+/-0.89 mm(2) (p=0.02). Area stenosis was 39+/-13% and 49+/-16% in the two groups, respectively (p=0.07). Re-endothelialization was 2.67+/-0.34 and 2.22+/-0.46 in the two groups, respectively (p<0.010). The injury score was similar between the two groups.

CONCLUSIONS

These data suggest that intramuscular administration of estrogen accelerates the endothelial cell repair in response to injury and reduces intimal hyperplasia in the porcine model.

Impaired effect of endothelin-1 on coronary artery stiffness in type 2 diabetes

AIM

We examined whether there is a differential effect of endothelin-A antagonism on coronary artery compliance in type 2 diabetes mellitus compared to non-diabetic patients.

PATIENT AND METHODS

We examined 32 patients, 11 type 2 diabetes mellitus and 21 non-diabetic patients, with atherosclerotic epicardial arteries free of significant luminal stenoses. Intracoronary BQ-123 (6 micromol), an endothelin-A receptor antagonist, was infused over 20 min. The artery lumen area in the proximal arterial segment was measured at end diastole and end systole before and after BQ-123 administration using an intravascular ultrasound catheter. Calculations were made of normalized arterial compliance index, in mm Hg(-1) x 10(3) and of arterial stiffness index beta.

RESULTS

Pulse pressure and heart rate did not change after BQ-123. In type 2 diabetes mellitus, normalized compliance index decreased from 1.79+/-1.36 at baseline to 1.29+/-0.82 after BQ-123 administration, whereas in non-diabetic patients it increased from 2.10+/-1.36 to 3.00+/-2.07 (p<0.05 versus baseline) (F=6.39, p=0.02). In type 2 diabetes mellitus, beta index increased from 1.97+/-0.53 to 2.46+/-0.95, whereas in non-diabetic patients it decreased from 1.83+/-0.95 to 1.63+/-0.84 (F=7.80, p=0.009). Big endothelin-1 at baseline was correlated with the baseline beta index (p<0.0001, r=0.68).

CONCLUSIONS

Big endothelin-1 is correlated with the coronary artery stiffness. The effect of endogenous endothelin-1 on coronary artery stiffness is impaired in type 2 diabetes mellitus. This may have important therapeutic implications with respect to the introduction of endothelin receptor antagonists as cardiovascular therapeutic agents.

Bosentan in Eisenmenger syndrome and chronic thromboembolic pulmonary hypertension

BACKGROUND

Bosentan, a dual endothelin receptor antagonist, has been used for symptomatic improvement of patients with idiopathic pulmonary arterial hypertension (PAH) and specific types of secondary (e.g. scleroderma and human immunodeficiency virus infection) PAH, but its efficacy in patients with congenital heart disease and chronic thromboembolic pulmonary hypertension is still under evaluation. In this study two patients are presented, one with common atrioventricular canal and pulmonary hypertension and the other with recurrent pulmonary thromboembolism; both improved significantly after bosentan administration.

MATERIALS AND METHODS

The first patient was a 38-year-old female with trisomy 21, common atrioventricular canal and pulmonary hypertension (Eisenmenger syndrome). The second patient was a 57-year-old male, who was on anticoagulant therapy owing to an episode of pulmonary embolism that had been diagnosed 3 years earlier. Recurrent pulmonary thromboembolism was considered the most probable diagnosis. Chest spiral computed tomography examination excluded pulmonary endarterectomy as a therapeutic approach. At admission, the two patients were on New York Heart Association class IV, diagnosed by progressive rest dyspnea. Bosentan was administered to patients 1 and 2 for 6 and 9 months, respectively (62.5 mg b.i.d. for 4 weeks, then 125 mg b.i.d.).

RESULTS

Bosentan therapy resulted in significant clinical improvement in both patients. No hepatic dysfunction nor any other side-effect was observed.

CONCLUSIONS

Bosentan could be an effective therapy for pulmonary hypertension owing to congenital heart disease and chronic thromboembolic disease.

Early, intracoronary growth hormone administration attenuates ventricular remodeling in a porcine model of myocardial infarction

OBJECTIVE

Ventricular remodeling is a common corollary of myocardial infarction. We hypothesized that this process may be attenuated by growth hormone, administered as a single high-dose, selectively in the infarct zone, early postmyocardial infarction.

DESIGN

In 35 pigs (29+/-4 kg), myocardial infarction was generated by inflation of an over-the-wire angioplasty balloon in the circumflex artery for 60 min and 5 further pigs were sham-operated. Ten minutes after reperfusion, the pigs were randomized (2:1) to either growth hormone (1 IU/kg) (n=23) or normal saline (n=12), delivered via the balloon catheter. All survivors were treated with captopril and were sacrificed 4 weeks after myocardial infarction.

RESULTS

Compared to controls, growth hormone-treated animals displayed lower heart weight (4.1+/-0.5 g/kg body weight, versus 3.4+/-0.4 g/kg, respectively, p=0.003) and dimensions (left ventricular short axis diameter 46+/-7 mm versus 37+/-6 mm, p=0.01; right ventricular short axis diameter 38+/-7 mm versus 30+/-5 mm p=0.001). Growth hormone increased wall thickness in the infarct (6.0+/-1.8 in controls versus 9.9+/-3.7 in treated animals, p=0.004) and non-infarct zones (10.6+/-1.8 in controls versus 15.5+/-3.8 in treated animals, p=0.0006) and produced higher (p<0.05) microvascular density in both zones.

CONCLUSION

Intracoronary administration of growth hormone attenuates left and right ventricular remodeling by inducing hypertrophy and by enhancing angiogenesis.

Endothelin receptor--a blockade decreases ventricular arrhythmias after myocardial infarction in rats

OBJECTIVE

Endothelin-1 (ET-1) production increases during acute myocardial infarction (MI) and may contribute to the genesis of ventricular tachycardia (VT) and ventricular fibrillation (VF). However, the antiarrhythmic effects of ET-1 receptor blockade, examined shortly after MI, have been debated. In the present study, we examined the effects of such treatment on VT/VF during the first 24 h post-MI.

METHODS

Thirty-five Wistar rats (223+/-22 g) were randomly allocated to either the ET-1 receptor-A (ETA) antagonist BQ-123 (0.4 mg/kg, BQ-123 group, n=17), or normal saline (control group, n=18) and were subjected to coronary artery ligation. A single-lead electrocardiogram was continuously recorded for 24 h post-MI, using an implanted telemetry system, and episodes of VT/VF were analyzed. Monophasic action potential (MAP) recordings were obtained from the left (LV) and right (RV) ventricular epicardium at baseline, 5 min after treatment and 24 h post-MI.

RESULTS

There were 15.94+/-19.35 episodes/h/rat of VT/VF in the control group and 1.66+/-2.22 in the BQ-123 group (p=0.010), resulting in a lower (p=0.030) arrhythmic mortality in treated animals. The mean episode duration was 7.40+/-7.16 s for the control group and 2.30+/-1.37 s for the BQ-123 group (p=0.011). The maximum decrease in VT/VF was observed during the 1st, 5th and 6th hours post-MI. In the control group, LV MAP duration increased 24 h post-MI, displaying an increased beat-to-beat variation, but remained unchanged in the BQ-123 group.

CONCLUSION

Acute ETA blockade reduces the incidence of VT/V F during the first 24-h post-MI in the rat, through a decrease in the dispersion of repolarization.

Intravenous Esmolol is Well Tolerated in Elderly Patients with Heart Failure in the Early Phase of Non-ST Elevation Myocardial Infarction

AIM

To investigate the haemodynamic response to and clinical safety and tolerability of intravenous esmolol (Brevibloc), Baxter Healthcare Corporation, Deerfield, Illinois, USA) in elderly and younger patients with acute non-ST elevation myocardial infarction (NSTEMI) and heart failure.

PATIENTS AND METHODS

We studied 24 consecutive patients, 12 of them elderly (> or =75 years old) and 12 younger (32-74 years old), with NSTEMI and symptoms of heart failure on presentation. After stabilisation of the patient's condition with standard therapy, intravenous esmolol was administered. An infusion rate of 0.05 mg/kg/min for 30 minutes was instituted and, if no adverse effects developed, this was increased to 0.20 mg/kg/min. All haemodynamic parameters were measured before and at the end of each administration using a Swan-Ganz catheter.

RESULTS

Only one patient in the elderly subgroup did not tolerate the augmented infusion rate (because of severe bradycardia) and so had to return to the initial lower infusion rate. The cardiac index (mean +/- SD) was 2.4 +/- 0.9 L/min/m(2) at baseline and decreased to 1.9 +/- 0.4 L/min/m(2) (p < 0.05 vs baseline) at the end of the administration of the second dose of esmolol in the elderly patients and 2.6 +/- 0.5 L/min/m(2) and 2.2 +/- 0.5 L/min/m(2) (p < 0.05 vs baseline), respectively, in the younger patients. Mean pulmonary wedge pressure was 17 +/- 6mm Hg at baseline and increased to 19 +/- 4mm Hg (p < 0.05 vs baseline) at the end of the second dose of esmolol in the elderly patients and 16 +/- 10mm Hg and 18 +/- 10mm Hg (p < 0.05 vs baseline), respectively, in the younger patients. The response of both age groups to esmolol was the same for all of the parameters examined.

CONCLUSION

Intravenous esmolol was safe and well tolerated in the early phase of NSTEMI in patients presenting with symptoms of heart failure and ongoing ischaemia, regardless of their age.