Role of coronary artery spasm in progression of organic coronary stenosis and acute myocardial infarction in a swine model. Importance of mode of onset and duration of coronary artery spasm

Coronary Artery Spasm-Related Heart Failure Syndrome: Literature Review

Although heart failure (HF) is a clinical syndrome that becomes worse over time, certain cases can be reversed with appropriate treatments. While coronary artery spasm (CAS) is still underappreciated and may be misdiagnosed, ischemia due to coronary artery disease and CAS is becoming the single most frequent cause of HF worldwide. CAS could lead to syncope, HF, arrhythmias, and myocardial ischemic syndromes such as asymptomatic ischemia, rest and/or effort angina, myocardial infarction, and sudden death. Albeit the clinical significance of asymptomatic CAS has been undervalued, affected individuals compared with those with classic Heberden's angina pectoris are at higher risk of syncope, life-threatening arrhythmias, and sudden death. As a result, a prompt diagnosis implements appropriate treatment strategies, which have significant life-changing consequences to prevent CAS-related complications, such as HF. Although an accurate diagnosis depends mainly on coronary angiography and provocative testing, clinical characteristics may help decision-making. Because the majority of CAS-related HF (CASHF) patients present with less severe phenotypes than overt HF, it underscores the importance of understanding risk factors correlated with CAS to prevent the future burden of HF. This narrative literature review summarises and discusses separately the epidemiology, clinical features, pathophysiology, and management of patients with CASHF.

Layered Plaque in Organic Lesions in Patients With Coronary Artery Spasm

Background

Coronary artery spasm plays a vital role in the pathogenesis of coronary plaques. We sought to investigate the plaque characteristics of co‐existing organic lesions in patients with coronary artery spasm in comparison to those without coronary artery spasm by intracoronary optical coherence tomography (OCT).

Methods and Results

We included 39 patients who presented with a symptom suspected of coronary spastic angina and had an organic lesion, defined as ≥plaque burden of 50% assessed by OCT. Coronary artery spasm was diagnosed by positive acetylcholine provocation test, or by spontaneous spasm detected during coronary angiography. A total of 51 vessels with an organic lesion were identified. Of these, coronary artery spasm was observed in 30 vessels (spasm), while not in 21 vessels (non‐spasm). Organic lesions in the spasm vessels, compared with those in the non‐spasm vessels, had a higher prevalence of layered plaque (93% versus 38%, P<0.001), macrophages (80% versus 43%, P=0.016), and intraplaque microchannels (73% versus 24%, P<0.001), and lower prevalence of macrocalcification (23% versus 62%, P=0.009) as assessed by OCT.

Conclusions

Layered plaque, macrophages, and intraplaque microchannels, were frequently observed in organic lesions in patients with coronary artery spasm. These findings suggest that coronary artery spasm induces local thrombus formation as well as active inflammatory response, therefore increasing the risk of rapid plaque progression and ischemic events in patients with coronary artery spasm.

Percutaneous coronary intervention in patients with documented coronary vasospasm during long-term follow-up

Objective

Although recurring coronary artery spasm (CAS) may lead to the development of fixed atherosclerotic coronary stenosis (FS), the relationship between coronary atherosclerosis and CAS is still speculative. We evaluated the incidence of FS requiring percutaneous coronary intervention (PCI) in patients with documented CAS during long-term follow-up and analysed their clinical features.

Methods

Clinical data of 3556 patients during a median follow-up of 9.4 years after non-invasive ergonovine spasm provocation testing with echocardiographic monitoring of left ventricular wall motion (erg echo) were analysed.

Results

Erg echo documented CAS in 830 (23.3%) patients, who had higher frequencies of coronary risk factors than those without CAS. Patients with documented CAS on erg echo showed significantly lower 10-year overall (90.5% vs 94.2%, p<0.001) and PCI-free (97.4% vs 98.4%, p=0.002) survival rates than those without CAS. Documented CAS was an independent factor associated with later PCI after adjustment by either Cox regression model or Fine-Gray competing risk model. There was no significant difference in baseline clinical characteristics between patients who needed later PCI and those who did not. Among 28 patients who needed later PCI after documentation of CAS, the original CAS and later PCI territory were concordant in 25 (89.3%), while 3 (10.7%) showed discordance.

Conclusions

CAS is a risk factor for the development of FS requiring PCI during long-term follow-up, and warrants physicians’ vigilance and careful follow-up of patients with documented CAS and insignificant stenosis of major epicardial coronary arteries at the time of initial diagnosis.

Role of acetylcholine spasm provocation test as a pathophysiological assessment in nonobstructive coronary artery disease

Coronary angiography (CAG) sometimes shows nonobstructive coronary arteries in patients with suspected angina or acute coronary syndrome (ACS). The high prevalence of nonobstructive coronary artery disease (CAD) in those patients has recently been reported not only in Japan but also in Western countries, and is clinically attracting attention. Coronary spasm is considered to be one of the leading causes of both suspected stable angina and ACS with nonobstructive coronary arteries. Coronary spasm could also be associated with left ventricular dysfunction leading to heart failure, which could be improved following the administration of calcium channel blockers. Because we rarely capture spontaneous attacks of coronary spasm with electrocardiograms or Holter recordings, an invasive diagnostic modality, acetylcholine (ACh) provocation test, can be useful in detecting coronary spasm during CAG. Furthermore, we can use the ACh-provocation test to identify high-risk patients with coronary spasm complicated with organic coronary stenosis, and then treat with intensive care. Nonobstructive CAD includes not only epicardial coronary spasm but also microvascular spasm or dysfunction that can be associated with recurrent anginal attacks and poor quality of life. ACh-provocation test could also be helpful for the assessment of microvascular spasm or dysfunction. We hope that cardiologists will increasingly perform ACh-provocation test to assess the pathophysiology of nonobstructive CAD.

Lymphocytic myocarditis occurs with myocardial infarction and coincides with increased inflammation, hemorrhage and instability in coronary artery atherosclerotic plaques

OBJECTIVE

Although lymphocytic myocarditis (LM) clinically can mimic myocardial infarction (MI), they are regarded as distinct clinical entities. However, we observed a high prevalence (32%) of recent MI in patients diagnosed post-mortem with LM. To investigate if LM changes coronary atherosclerotic plaque, we analyzed in autopsied hearts the inflammatory infiltrate and stability in coronary atherosclerotic lesions in patients with LM and/or MI.

METHODS

The three main coronary arteries were isolated at autopsy of patients with LM, with MI of 3-6h old, with LM and MI of 3-6h old (LM+MI) and controls. In tissue sections of atherosclerotic plaque-containing coronary segments inflammatory infiltration, plaque stability, intraplaque hemorrhage and thrombi were determined via (immuno)histological criteria.

RESULTS

In tissue sections of those coronary segments the inflammatory infiltrate was found to be significantly increased in patients with LM, LM+MI and MI compared with controls. This inflammatory infiltrate consisted predominantly of macrophages and neutrophils in patients with only LM or MI, of lymphocytes in LM+MI and MI patients and of mast cells in LM+MI patients. Moreover, in LM+MI and MI patients this coincided with an increase of unstable plaques and thrombi. Finally, LM and especially MI and LM+MI patients showed significantly increased intraplaque hemorrhage.

CONCLUSIONS

This study demonstrates prevalent co-occurrence of LM with a very recent MI at autopsy. Moreover, LM was associated with remodeling and inflammation of atherosclerotic plaques indicative of plaque destabilization pointing to coronary spasm, suggesting that preexistent LM, or its causes, may facilitate the development of MI.

Comparison of long-term clinical outcomes of percutaneous coronary intervention in vasospastic angina patients associated with significant coronary artery stenosis

BACKGROUND

Coronary spasm is the major pathophysiology of vasospastic angina (VA). Medical treatment is usually effective in VA patients without significant stenosis. However, there is little information about the percutaneous coronary intervention (PCI) in VA patients with significant coronary artery stenosis (CAS).

METHODS

After retrospective screening of all consecutive VA patients from January 2010 to April 2015, we selected significant CAS (>50% of diameter stenosis) after nitrate injection and divided them into two groups according to the presence of PCI.

RESULTS

A total of 220 VA patients (41 females, mean age: 58±10years old) were screened, and 85 were included in this study. Males were predominant in the VA with significant CAS group (89 vs 76%, p=0.020). PCI was done in 43 patients (51%). The most common culprit coronary artery was the left anterior descending coronary artery (18, 42%), diameter stenosis was significantly higher (66±9 vs 61±10%, p<0.01), and total number of antianginal medication was significantly lower in the PCI group than in the medical group (1.7±0.9 vs 2.1±0.8, p=0.039). Moreover, 4 patients underwent PCI to control symptoms in the medical treatment group during the follow-up period (26±13months). However, additional antiplatelet therapy was necessary in patients with coronary angioplasty, and there were 2 cases with complication associated with angioplasty (1 restenosis and 1 bleeding complication).

CONCLUSION

In VA patients with significant CAS, both treatment modalities showed similar clinical outcomes. Although the PCI can afford symptomatic improvement, it needed additional antiplatelet medications and can be associated with procedural complications.

Vascular Lesions in Nine Göttingen Minipigs with Thrombocytopenic Purpura Syndrome

Tissues from 9 Göttingen minipigs, aged 7 weeks to 1 year, with clinically diagnosed thrombocytopenic purpura syndrome were examined microscopically. All pigs had a history of spontaneous cutaneous purpura that was generally accompanied by disseminated visceral hemorrhages. Hematologic abnormalities included anemia (8 out of 9 pigs) and thrombocytopenia (7 out of 9 pigs), with platelet counts consistently below 20,000/μ. Microscopically, degenerative vascular lesions with morphologic features of arteriosclerosis were present in all 9 pigs. Vascular lesions affected small- to medium-sized muscular arteries and arterioles in various organs and extraparenchymal tissues; vessels of the renal pelvis and coronary arteries were consistently involved. Microscopic lesions in small- to medium-sized muscular arteries consisted of neointimal proliferation, medial thickening, luminal stenosis, thrombosis, disruption and fragmentation of the internal elastic lamina, necrosis of the tunica media, and medial deposits of myxoid matrix material. Microscopic lesions in arterioles included concentric laminar thickening of vessel walls (onion-skin pattern), endothelial cell hypertrophy, smooth muscle cell vacuolation, necrosis of the tunica media, thrombosis, and partial to complete luminal stenosis. Arteritis and/or periarteritis were also noted in 4 out of 9 pigs. Additional microscopic lesions included membranoproliferative glomerulonephritis (3 out of 9), myocardial microinfarcts (4 out of 7), renal interstitial fibrosis (2 out of 9), extramedullary hematopoiesis (6 out of 9), and intracapillary hyaline thrombi (2 out of 9). Degenerative vascular lesions have not been previously described in Göttingen minipigs with thrombocytopenic purpura syndrome. The etiopathogenesis of both the vascular lesions and thrombocytopenic purpura syndrome is currently unknown.

High susceptibility of atherosclerotic coronary arteries to the onset of vasospasm and angina pectoris-like symptoms due to coronary spasm in WHHLMI rabbits

We examined the relationship between atherosclerosis and the provocation of coronary spasm as well as the influence of coronary spasm on the onset of acute ischemic myocardial disease. Coronary spasm was provoked in anesthetized normal Japanese white (JW) rabbits and myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits, an animal model for coronary atherosclerosis and myocardial infarction, by injecting ergonovine during the infusion of norepinephrine through a marginal ear vein. A decrease in contrast flow in the left circumflex artery was observed on coronary angiograms. Ischemic changes were observed on the electrocardiograms of 29% (2/7) of JW and 79% (27/34, P=0.007) of WHHLMI rabbits. The frequency of coronary spasm was significantly high in rabbits with severe coronary plaques showing diffuse lesions. Left ventricle motility in vasospasm-positive rabbits, which was evaluated with echocardiograms, was decreased by 29% following the ergonovine injection (P<0.001), and every serum ischemic marker markedly increased 4 h after the provocation of vasospasm. These results demonstrate that atherosclerotic coronary arteries are positively related to the provocation of vasospasm, and vasospasm in severe atherosclerotic coronary segments evokes angina pectoris-like findings and/or non-fatal myocardial infarction. WHHLMI rabbits may be a novel animal model for angina pectoris and acute ischemic heart disease.

Impact of Statin Therapy on Clinical Outcome in Patients With Coronary Spasm

BACKGROUND

Statin therapy reduces the risk of cardiovascular events in patients with obstructive coronary artery disease. The aim of the present study was to determine the effects of statins on the prognosis of patients with coronary vasospastic angina (VSA) free of significant atherosclerotic stenosis.

METHODS AND RESULTS

After exclusion of 475 from 1877 consecutive patients who underwent an acetylcholine-provocation test between January 1991 and December 2010, data of 640 VSA patients without significant organic stenosis of the remaining 1402 were analyzed retrospectively. Propensity score matching was performed to reduce the effect of treatment-selection bias and possible confounders. The primary endpoint was major adverse cardiac events (MACE), including cardiac death, nonfatal myocardial infarction, and unstable angina. Among the study population, dyslipidemia on admission was identified in 160 of 168 (95.2%) patients of the statin group compared with only 125 of 472 (26.5%) of the no-statin group. Of the 640 patients, 24 (3.8%) developed MACE. Multivariate Cox hazard regression analysis identified statin therapy as a significant negative predictor of MACE (hazard ratio, 0.11; 95% CI, 0.02-0.84; P=0.033). In the propensity-score matched cohorts (n=128 each), Kaplan-Meier survival curve showed a better 5-year MACE-free survival rate for patients of the statin group compared to the no-statin group (100% vs 91.7%, respectively; P=0.002).

CONCLUSIONS

Statin therapy correlated with a lower rate of cardiovascular events in VSA patients free of significant organic stenosis. Statins seems to improve the prognosis of VSA patients free of significant organic stenosis.

Rapid Progression of Coronary Atherosclerosis: A Review

Atherosclerosis is chronic disease, the prevalence of which has increased steadily as the population ages. Vascular injury is believed to be critical initiating event in pathogenesis of spontaneous atherosclerosis. Syndrome of accelerated atherosclerosis has been classically described in patients undergoing heart transplantation, coronary artery bypass graft, and percutaneous transluminal coronary angioplasty. In contrast to spontaneous atherosclerosis, denuding endothelial injury followed by thrombus formation and initial predominant smooth muscle cell proliferation is believed to be playing a significant role in accelerated atherosclerosis. There is no universal definition of rapid progression of atherosclerosis. However most studies describing the phenomenon have used the following definition: (i) > or = 10% diameter reduction of at least one preexisting stenosis > or = 50%, (ii) > or = 30% diameter reduction of a preexisting stenosis <50%, and (iii) progression of a lesion to total occlusion within few months. Recent studies have described the role of coronary vasospasm, human immunodeficiency virus, various inflammatory markers, and some genetic mutations as predictors of rapid progression of atherosclerosis. As research in the field of vascular biology continues, more factors are likely to be implicated in the pathogenesis of rapid progression of atherosclerosis.

Vasospasm of atherosclerotic coronary arteries precipitates acute ischemic myocardial damage in myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits

OBJECTIVE

This study tested the hypothesis that vasospasm can trigger coronary plaque injury and acute ischemic myocardial damage.

APPROACH AND RESULTS

Myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits received an intravenous bolus of ergonovine maleate (0.45 µmol/kg) during intravenous infusion of norepinephrine (12 nmol/kg per minute) to provoke coronary spasm in vivo. After this treatment, coronary angiography demonstrated vasospasm, and the ECG showed ischemic abnormalities (ST depression/elevation and T-wave inversion) in 77% of animals (23/30). These changes normalized after nitroglycerin injection. In rabbits that demonstrated these ECG findings for >20 minutes, echocardiograms showed left ventricular wall motion abnormality. Serum levels of heart-type fatty acid-binding protein, cardiac troponin-I, and myoglobin increased markedly 4 hours after spasm provocation. In coronary lesions of myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits with provoked coronary spasm, we observed intimal injury in 60.9% in the form of endothelial cell protrusions (39.1%), denudation (30.4%), and macrophage extravasation (56.5%). Plaque disruption with luminal thrombus, however, was only seen in 2 of 23 animals (8.7%), and mural microthrombus was rarely observed (4.3%).

CONCLUSIONS

These observations show that provocation of vasospasm in myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits associates with subsequent ischemic myocardial damage. Although treatment with spasmogens altered aspects of plaque morphology, for example, endothelial protrusion and macrophage emigration, thrombosis was rare in these animals with chronic atherosclerotic disease.

Subclavian steal syndrome presenting as recurrent pulmonary oedema associated with acute left ventricular diastolic dysfunction

Subclavian steal syndrome typically presents as angina in patients with internal mammary artery grafts. Atypical clinical presentations have been rarely described. We report an unusual case of subclavian steal syndrome presenting as pulmonary oedema with acute left ventricular diastolic dysfunction and preserved ejection fraction in a patient with internal mammary artery graft and severe stenosis of the proximal left subclavian artery. After successful angioplasty and stenting of subclavian artery, the patient remained asymptomatic for six months, but then experienced acute diastolic dysfunction and recurrent pulmonary oedema associated with critical subclavian in-stent restenosis with stent deformation. This report points out that, in patients with internal mammary-to-LAD grafts, subclavian steal syndrome may present as acute left ventricular diastolic dysfunction and pulmonary oedema even in the presence of normal ejection fraction.

Coronary arterial wall disruption and intramural hematoma in a patient with coronary spastic angina

Acute myocardial infarction is sometimes complicated in patients with coronary spastic angina. The mechanisms are known to be plaque rupture and thrombosis induced by spasm, and reduced coronary flow due to prolonged spasm. We describe the case of a 45-year-old woman with coronary spastic angina who had a complication of an acute myocardial infarction. A specimen obtained with thrombectomy was the disrupted coronary artery wall accompanied by massive intramural hemorrhage. The cause of the acute myocardial infarction was thought to be an embolism of the coronary arterial wall that was disrupted by spasm and intramural hemorrhage.

A Case of Acute Myocardial Infarction With ST-Segment Elevation in a Lead Augmented Right Vector Caused by a Left Main Coronary Artery Vasospasm

Diagnosing and selecting an appropriate treatment strategy for left main coronary artery (LMCA) obstruction is very important. Although this disease is not frequently encountered, it can cause severe hemodynamic deterioration resulting in a less favorable prognosis without a suitable management approach. Another aspect of LMCA that we must not overlook is coronary artery spasm, which can be an infrequent but important cause of acute coronary syndrome. Although it is rare, LMCA can cause critical complications. In this study, we report the case of a 35-year-old female who was admitted to the hospital with a diagnosis of acute myocardial infarction with ST-segment elevation in the aVR lead caused by a left main coronary spasm that was examined on intravascular ultrasound.

Intermediate fixed coronary artery stenosis at the site of ergonovine-provoked spasm as a predictor of long-term major adverse cardiac events of patients with coronary spastic angina

BACKGROUND

Organic coronary artery stenosis is a significant prognostic factor in patients with coronary spastic angina (CSA), so the present study was focused on assessing the impact of intermediate fixed stenosis at sites of provoked spasm on the long-term outcomes of CSA patients.

METHODS AND RESULTS

CSA patients diagnosed on the basis of ergonovine-provoked spasm were enrolled and the clinical background and long-term prognosis of CSA patients with intermediate fixed stenosis at the site of provoked spasm (with-fixed-stenosis group, n=37) and those without fixed stenosis (without-fixed-stenosis group, n=126) were retrospectively compared. During the follow-up period (average 4.01 years for with-fixed-stenosis, 4.47 years for without-fixed-stenosis), the with-fixed-stenosis group had a significantly lower event-free survival rate, as well as a higher frequency of admission for unstable angina and percutaneous coronary intervention than the without-fixed-stenosis group, whereas the survival rate did not differ significantly between the 2 groups. In the multivariate analysis, intermediate fixed stenosis at the site of provoked spasm was a predictor of long-term major adverse cardiac events (MACE).

CONCLUSIONS

Intermediate fixed stenosis at the site of ergonovine-provoked spasm is an independent risk factor for MACE during the long-term period in CSA patients.

Coronary vasospasm-induced acute coronary syndrome complicated by life-threatening cardiac arrhythmias in patients without hemodynamically significant coronary artery disease

BACKGROUND

Coronary vasospasm-induced electrical and mechanical complications in patients with acute coronary syndrome and no hemodynamically significant coronary artery disease are rarely reported.

METHODS

A total of 733 consecutive patients with acute coronary syndrome admitted to our hospital who subsequently underwent coronary angiography at our institution were enrolled. Patients who had documented complete atrioventricular block or ventricular fibrillation, no evidence of hemodynamically significant coronary artery disease on coronary angiogram, and no other (non-coronary) cardiac abnormalities were included. Patients were followed for subsequent cardiac events and mortality.

RESULTS

Over a 6-year period at our institution, acute coronary syndrome complicated by life-threatening cardiac arrhythmias developed in six patients who had no hemodynamically significant coronary artery disease with corresponding intra-coronary ergonovine provocative coronary vasospasm. Acute myocardial infarction was diagnosed in five of these patients and variant angina pectoris in one. Complete atrioventricular block was the most common complication in these cases, followed by cardiogenic shock with or without right ventricular infarction, ventricular fibrillation, and severe sinus arrest. These complications were corrected with intravenous fluid, intravenous atropine or cardiac defibrillation. During a median follow-up period of 26 months, none of the patients expired or suffered nonfatal reinfarction. Two individuals who did not stop smoking during follow-up developed recurrent angina after self-discontinuation of calcium antagonists.

CONCLUSIONS

Coronary vasospasm can be a cause of life-threatening cardiac arrhythmias in patients with acute coronary syndrome and no hemodynamically significant coronary artery disease. Coronary angiography with/without intra-coronary ergonovine testing is necessary in acute coronary syndrome patients to identify the underlying pathology and establish appropriate treatment in these cases.

Recurrent ST-segment elevations in a patient without significant coronary disease

We report a case of recurrent ST-segment elevations totaling 7 times over 3 hours during subtotal gastrectomy and the early postoperative period in a patient with no history of coronary artery disease. Possible contributing factors include cold stimulus, epidural anesthesia, and inadequate depth of anesthesia. The first episode almost resulted in cardiac arrest and was treated with intravenous epinephrine. The second episode was associated with ventricular fibrillation, which was treated with defibrillation and intravenous verapamil. The third to the seventh episodes were successfully treated with intravenous nitrate. The electrocardiographic changes and postoperative coronary angiography were consistent with a clinical diagnosis of coronary artery spasm. This case suggests that coronary artery spasm is capable of occurring repeatedly in a cyclic pattern during perioperative periods.

Lesion Severity and Hypercholesterolemia Determine Long-Term Prognosis of Vasospastic Angina Treated With Calcium Channel Antagonists

Although patients with medically treated vasospastic angina have a good outcome, few data exist regarding the role of underlying lesion severity associated with or without hyperlipidemia in the prognosis. Therefore, the aim of the present study was to assess the relationship between the long-term outcome of vasospastic angina and the factors influencing its prognosis. A total of 256 patients (219 men, 37 women; mean age, 54.1+/-9.2) who had coronary spasm with or without underlying lesions and were being treated with calcium channel antagonists were enrolled and followed for 13.6+/-3.7 years. Cardiac events consisted of cardiac death and ischemic events, which included acute myocardial infarction and unstable angina. Cox analysis selected coronary artery stenosis (CAS, >/=50%) and risk factors such as age, hypertension, diabetes mellitus, low-density lipoprotein-cholesterol (LDL-C), sex and smoking. There were 19 cases of cardiac death (7.4%) and 58 of ischemic events (22.7%) during the follow-up period. The presence of significant CAS was an independent predictor of event-free survival (hazard ratio (HR) =2.84, 95% confidence interval (CI) =1.79-4.52, p<0.0001). In 193 patients without significant CAS, there were 10 cases of cardiac death (5.2%, p<0.05) and 34 of ischemic events (17.6%, p<0.01). In that group, high LDL-C was the independent predictor of event-free survival (HR = 3.89, 95% CI = 1.20-12.6, p=0.02). Kaplan-Meier survival analysis revealed significantly lower event-free survival in patients with than in those without lesions (p<0.0001 by log-rank test). These results demonstrate that the most important factor for long-term prognosis of vasospastic angina treated with calcium channel antagonists is significant CAS. High LDL-C, which might alter the underlying coronary endothelial function and/or accelerate atherosclerotic lesions, could also contribute to the occurrence of cardiac events, particularly in patients without significant CAS.

Plaque Morphology at Coronary Sites With Focal Spasm in Variant Angina-Study Using Intravascular Ultrasound-

In the present study, the intravascular ultrasound (IVUS) morphologic appearance of coronary atherosclerotic plaque associated with focal spasm was prospectively studied in 45 patients with or without focal coronary spasm provoked by ergonovine or acetylcholine. The percent plaque area and plaque arc were determined from the IVUS images at the sites of spasm. Calcified lesion was defined as the presence of high-intensity echo with acoustic shadowing. Twenty-three patients had focal coronary spasm defined as angiographic narrowing >75% and IVUS demonstrated atherosclerotic plaque in these 23 sites. In the 22 patients without focal spasm, IVUS demonstrated 18 atherosclerotic lesions in 17 patients and the remaining 5 patients did not have significant lesions. There was no difference in the percent plaque area and plaque arc between plaque lesions with (47+/-10%, 298+/-71 degrees ) and without (39+/-15%, 249+/-83 degrees ) coronary spasm. Interestingly, calcified lesion was less frequently present at the sites with than at those without spasm (p<0.05). These results indicate that the presence of plaque without calcification is likely to be related to the occurrence of focal vasospasm, although the severity and distribution of the disease did not differ between each patient group.

Causes of complications from cervical spine manipulation

Cervical manipulation occasionally causes serious vertebrobasilar complications. The usual cause is vertebral artery dissection, however in some cases there has been no obvious arterial injury. The present paper reviews the mechanisms by which complications occur, particularly when the applied force is trivial or there is no injury to the vertebral arteries, and the factors that increase risk of complications. In addition, implications are drawn for use of the recently revised Australian Physiotherapy Association (APA) guidelines. In the absence of vertebral artery rupture, complications are proposed to arise from vasospasm, haemostasis, endothelial injury or turbulent flow. These mechanisms have a sound scientific basis but have yet to be demonstrated as specifically causing vertebrobasilar complications. The most important risk factors for vertebrobasilar complications appear to be prior trauma to the vertebral arteries and symptoms of vertebrobasilar ischaemia from previous manipulation. There is weak evidence that hypoplasia of the vertebral arteries also increases the risk of complications. Neither general vascular factors nor pre-existing degenerative conditions of the cervical spine increase risk of vertebrobasilar complications. The procedures described in the APA guidelines test adequacy of total cerebral perfusion during cervical movements rather than patency of the vertebral arteries or their susceptibility to injury. The guidelines may therefore indicate potential for surviving a complication from manipulation. They may also identify patients at risk of complications from minor trauma. It is recommended that the procedures described in the APA guidelines be applied prior to every manipulation, and that manipulation be avoided in the presence of any signs of vertebrobasilar insufficiency.

Our animal model of coronary spasm--my personal view

We developed an animal model of coronary spasm in swine, similar to coronary spasm in patients with variant angina based on the angiographic findings. In this animal model, an impairment of endothelium dependent dilatation appeared to play a minor role while the hypercontraction of the medial muscle cells by histamine and serotonin at the spastic site played a major role in the induction of coronary spasm. In Göttingen male miniature swine receiving focal endothelial denudation, moderate hypercholesterolemia and X ray irradiation, the abrupt, severe and prolonged coronary spasm resulted in a sudden progression of organic coronary stenosis mainly due to intraplaque hemorrhage and also in acute myocardial infarction.

Differences between coronary hyperresponsiveness to ergonovine and vasospastic angina

The objective of the present study was to investigate the differences between coronary hyperresponsiveness without ischemia and vasospastic angina in an ergonovine provocation test using multivariate analysis. We have sometimes experienced a more than 50% narrowing response of vascular diameter without ischemia in a coronary response to ergonovine. We studied 107 patients with less than 50% stenosis in a coronary arteriogram. Their vascular responses to ergonovine were measured and the patients were divided into three groups, as follows: Group 1 had 50% or less vascular narrowing response without ischemia; Group 2 had a vascular hyperresponsiveness of more than 50% narrowing response without ischemia; and Group 3 experienced a hyperresponsiveness with ischemia. The degree of coronary response was found to be related to smoking, inpaired glucose tolerance (IGT) and the Gensini score by multiple regression analysis. A multiple logistic analysis revealed that the Gensini score and smoking were significant predictive factors for Group 3 (odds ratio: 1.20 and 8.97). The only factor different between Group 2 and Group 1 was gender. The coronary hyperresponsiveness to ergonovine without ischemia differs from vasospastic angina in the degree of coronary atherosclerosis and smoking habits. The patients with hyperresponsiveness had similar characteristics to those with atypical chest pain rather than vasospastic angina, except for a gender difference.

Increased expression of L-type calcium channels in vascular smooth muscle cells at spastic site in a porcine model of coronary artery spasm

Coronary artery spasm is caused primarily by increased contractility of vascular smooth muscle. Excessive Ca2+ entry into vascular smooth muscle cells (VSMCs) may be one of the key mechanisms for the spasm, but no study has ever directly examined the possible alterations of Ca2+ channels in the spastic coronary artery. Here we show that L-type Ca2+ channels are excessively expressed at the spastic site of the coronary artery. In a porcine model of coronary spasm with balloon injury, both receptor-mediated stimulation of L-type Ca2+ channels by serotonin and direct stimulation of the channels by Bay K 8644 (a dihydropyridine Ca2+ channel agonist) repeatedly induced coronary spasm in vivo, which was abolished by pretreatment with nifedipine, a dihydropyridine Ca2+ channel antagonist. In a single VSMC freshly dispersed from coronary arteries in vitro, patch-clamp experiments showed that current density of L-type Ca2+ channel current was significantly increased in VSMCs from the spastic site compared with that from the control site even when the channels were maximally stimulated by Bay K 8644. There was no difference in the sensitivity of the channels to Bay K 8644. These results indicate that functionally available L-type Ca2+ channels are excessively expressed at the spastic site of the coronary artery in our porcine model, suggesting that increased expression of L-type Ca2+ channels and concomitant increase in Ca2+ entry into VSMCs through the channels may contribute, at least in part, to the pathogenesis of coronary artery spasm.

Cellular and molecular mechanisms of coronary artery spasm: lessons from animal models

Coronary artery spasm plays an important role in the pathogenesis of a wide variety of ischemic heart diseases, especially in the Japanese population. Because coronary artery spasm can be induced by a variety of stimuli with different mechanisms of action, the occurrence of the spasm appears to be due to the local hyperreactivity of the coronary artery rather than to an enhanced stimulation with a single mechanism of action. Several lines of evidence indicate that coronary artery spasm is caused primarily by smooth muscle hypercontraction whereas the contribution of endothelial dysfunction may be minimal. In order to elucidate the cellular and molecular mechanisms of the spasm, porcine models of the spasm were developed. In the first model with balloon injury and high-cholesterol feeding, a close topological correlation between the early atherosclerotic lesions and the spastic sites was noted, whereas in the second model with an inflammatory cytokine the potential importance of coronary inflammatory changes, especially at the adventitia, was noted. Subsequent studies in vivo and in vitro demonstrated that protein kinase C (PKC) and Rho-kinase are substantially involved in the intracellular mechanism of the spasm, resulting in increases in the mono- and diphosphorylations of myosin light chain (MLC). Furthermore, molecular biological analyses demonstrated that Rho-kinase is upregulated at the spastic site (at all levels, including mRNA, protein, and activity), resulting in the inhibition of MLC phosphatase through the phosphorylation of its myosin binding subunit and thereby causing the increase in MLC phosphorylations. Preliminary results also suggest that the long-term inhibition of Rho-kinase is effective in inhibiting the development of arteriosclerotic vascular lesions in several porcine models. Thus, Rho-kinase could be regarded as a novel therapeutic target for coronary arteriosclerosis in general and coronary artery spasm in particular.

Coronary artery vasomotion and post-stenotic coronary artery blood flow after intracoronary lacidipine in patients with ischaemic heart disease: a pilot study

BACKGROUND

The calcium antagonist lacidipine has been shown to be highly vasoselective and to improve myocardial perfusion in hypertensive patients. However, its effects on coronary artery vasomotility and on post-stenotic coronary flow reserve in patients with atherosclerotic heart disease are unknown.

OBJECTIVES

This study was designed to investigate the acute direct effects of repeated infusions of lacidipine on epicardial coronary artery vasomotion and on post-stenotic coronary artery blood flow in patients with stable angina pectoris and angiographic evidence of coronary heart disease.

METHODS

In 8 patients with stable angina and moderate to severe stenosis of the left coronary artery, measurements of epicardial dimensions (quantitative angiography) and of coronary blood flow (Doppler guidewire) distal to a stenosis were performed at baseline and after 3 repeated intracoronary boluses of 12 microg of lacidipine. Results were compared with those obtained after 10 mg of intracoronary papaverine.

RESULTS

The intracoronary administration of lacidipine was well tolerated, without any adverse effects. Lacidipine significantly increased the minimal luminal diameter of the lesion (peak relative increase of 43.7%), without significant changes in heart rate and systolic aortic pressure. Intracoronary lacidipine caused a dose-dependent increase in coronary flow reserve. Maximal vasodilatory effects were equivalent to those obtained with intracoronary papaverine.

CONCLUSIONS

These results suggest that lacidipine acts directly as a potent vasodilator in stenotic epicardial vessels and improves myocardial perfusion distal to a moderately severe stenosis in patients with stable angina.

Histological evaluation of coronary plaque in patients with variant angina: relationship between vasospasm and neointimal hyperplasia in primary coronary lesions

OBJECTIVES

This study was designed to determine whether coronary vasospasm in patients with variant angina pectoris (VAP) may produce focal organic lesions at the site of vasospasm that would contribute to disease progression.

BACKGROUND

Recent clinical angiographic and experimental studies have demonstrated the potential role of vasospasm in the worsening of organic coronary stenosis.

METHODS

We studied histologically the coronary plaques obtained at atherectomy in 202 patients with moderate to severe coronary stenosis. This population included 22 patients with VAP, 100 patients with chronic stable angina and 80 patients with restenosis following angioplasty or atherectomy. Diagnosis of VAP was based on both the clinical feature of angina at rest associated with ST elevation and a positive response to acetylcholine provocation test.

RESULTS

The most common histological appearance in 92% of patients with stable angina was hypocellular fibroatheromatous plaques, whereas neointimal hyperplasia was the characteristic feature of the plaque observed in 90% of patients with restenosis. The coronary specimens at the site of spasm in 15 of the 22 patients (68%) with VAP demonstrated intimal injuries such as neointimal hyperplasia (15), thrombus formation (2), and intimal hemorrhage (3). Neointimal hyperplasia was significantly more common in the patients with VAP as compared with those with stable angina (68% vs. 8%; p < 0.0001). A rapid progression of organic stenosis within three years was angiographically found in 5 of the 22 patients with variant angina. In all five cases, neointimal hyperplasia was the main contributor to the worsening of the organic lesion at the site of spasm. These histological findings in patients with VAP extremely resembled those in restenosis. Except for vasospasm, no factors significantly predicted the presence of neointimal formations in primary coronary lesions.

CONCLUSIONS

Coronary vasospasm may provoke vascular injury that leads to the formation of neointima in VAP patients similar to that seen with restenosis. Coronary spasm may thus play a key role in the rapid coronary stenosis progression in certain patients with VAP.

Aortic medial necrosis with or without thrombosis in rabbits treated with Russell's viper venom and angiotensin II

The aim of the present study is primarily to re-examine an animal model of acute myocardial infarction (AMI) and arterial thrombosis, developed by Constantinides and his colleagues in the 1960s, in both heritable hyperlipidemic rabbits and normal rabbits because they did not study these rabbits. The groups in this study consisted of 29 normal rabbits and 29 Watanabe heritable hyperlipidemic (WHHL) rabbits. These rabbits were administered Russell's viper venom (RVV) as a procoagulant, intraperitoneally with serotonin or angiotensin II or saline, intravenously. As a control, 10 normal and 17 WHHL rabbits were administered intravenously with either angiotensin II or saline. These treatments were given on 2 successive days. AMI lesion was found in 8 of 29 normal and 7 of 29 WHHL rabbits receiving RVV and angiotensin or serotonin. Angiotensin II promoted the incidence of aortic thrombosis associated with segmental medial necrosis and an intimal disruption in WHHL rabbits receiving RVV. In the normal rabbits, angiotensin II in addition to RVV induced segmental medial necrosis of the aorta, but angiotensin II alone did not. Thus, we postulated that a synergistic effect of RVV as a cytotoxic substance and a sudden increase in the aortic wall tension by angiotensin II might thus result in acute aortic medial necrosis. The conclusion was that no close correlation between coronary arteriosclerosis and AMI was found in this animal model. The intravenous administration of angiotensin promoted aortic medial necrosis even in normal rabbits treated with RVV and then accelerated aortic thrombosis in the WHHL rabbits treated with RVV.

Coronary vasomotion during dynamic exercise: influence of intravenous and intracoronary nicardipine

OBJECTIVES

Our aim was to evaluate the influence of a calcium channel blocking agent of the dihydropyridine group (nicardipine) on coronary vasomotion during dynamic exercise.

BACKGROUND

Coronary vasomotion plays an important role in the pathophysiology of myocardial ischemia.

METHODS

Twenty-nine patients with coronary artery disease were studied at rest and during bicycle exercise with the use of biplane quantitative coronary angiography. Twelve patients without pretreatment (group 1) served as control subjects. Seventeen patients (group 2) received nicardipine, either 0.2 mg by intracoronary injection (n = 9) or 2.5 mg intravenously (n = 8) before exercise.

RESULTS

In the control group there was exercise-induced vasoconstriction (-29%, p < 0.001) of the stenotic segment but coronary vasodilation (+22%, p < 0.05) of the normal vessel segment. In group 2, nicardipine induced coronary vasodilation of both the normal (+16%, p < 0.001) and the stenotic vessel segment (+35%). During subsequent exercise there was some additional vasodilation of normal (+4%, p = NS) and stenotic arteries (+5%, p = NS). There was no difference between either intracoronary or intravenous nicardipine with regard to vasodilation. Application of sublingual nitroglycerin was associated with significant vasodilation of the normal vessel segment in groups 1 (+18%, p < 0.05) and 2 (+15%, p < 0.001). The stenotic vessels showed a significant increase in percent cross-sectional area after nitroglycerin in groups 1 (+12%, p = NS) and 2 (+51%, p < 0.001). Exertional angina pectoris occurred less frequently in group 2 (18%) than in group 1 (67% [p < 0.005 vs. group 2]); group 2 also had a smaller increase in mean pulmonary artery pressure (+14 vs. +21 mm Hg, p < 0.05).

CONCLUSIONS

Exercise induces vasoconstriction of stenotic, but vasodilation of normal, coronary vessel segments. Intravenous and intracoronary nicardipine prevent vasoconstriction of stenotic coronary arteries during exercise and exert a significant anti-ischemic effect. The combination of two anti-ischemic drugs, nitroglycerin and nicardipine, has an additive effect on coronary vasomotion that is seen only in the stenotic vessel segment. Thus, the anti-ischemic action of nicardipine is mainly due to a primary effect on coronary vasomotor response rather than to secondary effects such as changes in loading conditions.

Mechanisms of coronary hyperconstriction in response to serotonin induced by X-irradiation in miniature pigs: increased constrictive response of medial smooth muscle

Experimental and clinical studies suggest that X-irradiation to the coronary artery may enhance vasoconstrictive response. This study aimed to clarify the effect of X-irradiation on the vasomotor response of porcine coronary artery. X-ray (15 Gy) was selectively irradiated to the left anterior descending coronary artery (LAD) in 14 Göttingen miniature pigs. The coronary vasomotor responses to serotonin at the irradiated site (LAD) and the control site (the left circumflex artery; LCX) were assessed by quantitative arteriography before and 1 h and 1, 2, and 4 weeks after X-irradiation. At 2 weeks, endothelium-dependent vasodilation in response to substance P was also evaluated arteriographically in vivo. At 2 weeks, isometric tension studies were performed to evaluate the constrictive responses of medial muscle strips and endothelium-dependent relaxation. Coronary vasoconstriction in response to serotonin was enhanced 1 week after, and further augmentation was noted 2 and 4 weeks after X-irradiation. Endothelium-dependent vasodilation in response to substance P in vivo was preserved 2 weeks after X-irradiation. Coronary arteriography showed no organic stenosis at the irradiated site. In vitro studies demonstrated that medial muscle strips of the irradiated site showed hypercontraction in response to serotonin and that endothelium-dependent relaxation in response to serotonin and substance P was preserved at the irradiated site. A histological study revealed no appreciable changes of the endothelial cells or intimal thickening.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial ischemia after cardiopulmonary bypass

Intraoperatively, myocardial ischemia is more common after cardiopulmonary bypass (CPB) than before CPB. Ischemia associated with coronary vasospasm and thrombosis may be much more common toward the end of surgery and early in the postoperative period than previously appreciated. This may be because the coagulation system is altered during CPB, and the coronary endothelium is damaged significantly as a result of cardioplegic arrest followed by reperfusion. In this milieu, vasospasm and thrombosis may be caused by the administration of protamine. Some of the ischemia observed in this period actually is not reversible and is associated with myocardial injury and infarction. It may be ameliorated by the administration of calcium channel blockers, aspirin, and anticoagulants. Electrocardiography may be the most suitable modality for the detection of ischemia after CPB and postoperatively. During this period, many episodes of ST deviation are of a nonischemic etiology, and the ECG needs careful interpretation. Transesophageal echocardiography is suitable for use intraoperatively and early on in the intensive care unit.

Mechanisms of ergonovine-induced hyperconstriction of coronary artery after x-ray irradiation in pigs

Mechanisms of ergonovine-induced coronary hyperconstriction were examined in vivo and in vitro in miniature pigs. To provoke coronary hyperconstriction, the endothelium of a segment of a major branch of the left coronary artery was denuded in 19 Göttingen miniature pigs (4 to 6 months of age). In Group I (n = 12), the denuded site of the coronary artery was selectively irradiated with 15Gy of x-ray twice, 3 and 4 months after endothelial denudation. The remaining 7 pigs were not irradiated (Group II). The vasoconstrictive effect of intracoronary administration of ergonovine (1 to 1000 microgram) was examined angiographically 3 months (just before irradiation in group I) and 5 months after denudation in the two groups. After the angiographical study, the vessels were isolated and isometric tensions were measured in an organ chamber. In the in vivo studies, ergonovine-induced vasoconstriction at the denuded and x-ray irradiated site in Group I was significantly greater than that at the control site or that at the denuded site in Group II. Pretreatments with serotonin receptor blockers (ketanserin or methysergide) significantly attenuated ergonovine-induced hyperconstriction, while an alpha-adrenergic receptor blocker (prazosin) did not (% inhibition; ketanserin 74 +/- 9%, p < 0.01, methysergide 60 +/- 10%, p < 0.01, prazosin 9 +/- 5%, NS). In the in vitro studies, ergonovine produced significantly greater tension at the denuded and x-ray irradiated site (Group I) than at the control site or at the denuded site (Group II). Ergonovine-induced endothelium-dependent relaxation was impaired at the denuded site in both groups to a similar extent. These results suggest that ergonovine-induced hyperconstriction at the denuded and x-ray irradiated coronary artery resulted mainly from the hyperreactivity of medial smooth muscle mediated by serotonin receptors.

Role of coronary vasospasm in the pathogenesis of myocardial infarction: study in patients with no significant coronary stenosis

The role of coronary vasospasm in the pathogenesis of myocardial infarction is unclarified. Among 212 patients with myocardial infarction in whom percutaneous transluminal coronary angioplasty (PTCA) or coronary thrombolysis was not performed at the acute stage, 21 patients (10%) showed no significant coronary stenosis (the degree of stenosis was less than 50% of the luminal diameter) by coronary angiography 4 weeks after myocardial infarction. Among them, 11 (52%) had preinfarction angina at rest, including two with variant angina, and nine (43%) had postinfarction angina at rest. Intracoronary ergonovine maleate induced coronary vasospasm in 12 (75%) of 16 patients examined. Coronary vasospasm occurred in the infarct-related coronary arteries in all patients, and importantly, multivessel coronary vasospasm occurred in 11 patients (69%). The infarct size was relatively small in these patients: (1) seven patients (33%) had Q wave myocardial infarction while 14 patients (67%) had non-Q wave myocardial infarction; (2) peak creatine phosphokinase (CPK) was lower than 1000 IU/ml in all patients; and (3) thallium-201 (Tl-201) scintigraphic study showed no perfusion defect in 8 of 18 patients. There was only one patient with congestive heart failure and no patient died. These results suggest that coronary vasospasm may play an important role in the pathogenesis of myocardial infarction in patients without significant coronary stenosis. The relatively small infarct size suggests that coronary reperfusion occurred in the early stages of myocardial infarction.