Significance of spasm in the pathogenesis of ischemic heart disease

Surgical removal of multiple left ventricular thrombi with video-assisted cardioscopy: a case report

Background

Left ventricular (LV) thrombus is a lethal complication of coronary artery disease that can lead to embolization and sudden death. There is no clear consensus on the optimal treatment for LV thrombi. There is a paucity of case series about surgical excision of LV thrombus in patients with coronary vessel disease. For that, there is insufficient evidence to support surgical excision of LV thrombus and recommend the optimal timing of this procedure.

Case summary

We report a case of a 52-year-old man with a history of percutaneous catheter intervention for mid-right coronary artery lesion 3 years ago. He presented with two-vessel coronary artery disease with three LV thrombi. The thrombi were mobile and protuberant. We performed coronary artery bypass grafting in both vessels and LV thrombectomy with video-assisted cardioscopy.

Discussion

Mobile or protuberant thrombus is the most important risk factor for embolization of LV thrombus. On the other hand, LV thrombus size rarely appears in studies as a risk factor for embolization, and when it does, it is a lesser risk factor. There are no case reports describing simultaneous formation of three LV thrombi after myocardial infarction, and it is not known if the risk of embolism is high in such cases. Our patient had very fragile thrombi, and thrombectomy was performed along with coronary artery bypass grafting due to the high risk of embolism.

Coronary Microvascular Spasm: Clinical Presentation and Diagnosis

Professor Maseri pioneered the research and treatment of coronary vasomotion abnormalities represented by coronary vasospasm and coronary microvascular dysfunction (CMD). These mechanisms can cause myocardial ischaemia even in the absence of obstructive coronary artery disease, and have been appreciated as an important aetiology and therapeutic target with major clinical implications in patients with ischaemia with non-obstructive coronary artery disease (INOCA). Coronary microvascular spasm is one of the key mechanisms responsible for myocardial ischaemia in patients with INOCA. Comprehensive assessment of coronary vasomotor reactivity by invasive functional coronary angiography or interventional diagnostic procedure is recommended to identify the underlying mechanisms of myocardial ischaemia and to tailor the best treatment and management based on the endotype of INOCA. This review highlights the pioneering works of Professor Maseri and contemporary research on coronary vasospasm and CMD with reference to endothelial dysfunction, Rho-kinase activation and inflammation.

A review of strategies for infarct size reduction during acute myocardial infarction

Advances in medical and interventional therapy over the last few decades have revolutionized the treatment of acute myocardial infarction. Despite the ability to restore epicardial coronary artery patency promptly through percutaneous coronary intervention, tissue level damage may continue. The reported 30-day mortality after all acute coronary syndromes is 2 to 3%, and around 5% following myocardial infarction. Post-infarct complications such as heart failure continue to be a major contributor to cardiovascular morbidity and mortality. Inadequate microvascular reperfusion leads to worse clinical outcomes and potentially strategies to reduce infarct size during periods of ischemia-reperfusion can improve outcomes. Many strategies have been tested, but no single strategy alone has shown a consistent result or benefit in large scale randomised clinical trials. Herein, we review the historical efforts, current strategies, and potential novel concepts that may improve myocardial protection and reduce infarct size.

Myocardial infarction with normal coronaries: an unexpected finding in a 13-year-old girl with systemic lupus erythematosus

We report a 13-year-old girl diagnosed with systemic lupus erythematosus (SLE) who presented with left-sided chest pain, with ECG changes and elevation troponins that were suggestive of an acute inferior wall myocardial infarction (MI). Her multi-slice computed tomography coronary angiogram and standard angiogram were normal. The cardiac magnetic resonance imaging revealed an area of infarcted myocardium that was in the right coronary artery territory. We believe her MI was most likely secondary to coronary vasospasm. MI is rare and coronary vasospasm is an uncommon cause of MI in children and adolescents with SLE.

Vasospastic angina: control of disease activity and efficacy of drug treatment using the prolonged hyperventilation test

Sixteen consecutive patients with vasospastic angina underwent a control provocation test in the coronary care unit or the cardiac catheterization laboratory in order to evaluate the disease activity and the efficacy of long-term calcium antagonist treatment. In patients without angina at rest, the prolonged hyperventilation test was negative in 10/10 patients on calcium antagonist treatment (group A + B) and in 4/5 patients without medication (group C). The test was positive in 1/1 patient with angina at rest without medication (group D). However, the test provoked vasospastic angina in 1/5 patients who were asymptomatic without medication. In both the latter patients the prolonged hyperventilation test became negative after the restart of calcium antagonist treatment. During a mean follow-up period of 18 months (range 16-19) after the control hyperventilation test, no relapse of angina at rest, arrhythmias, syncopes, deaths or myocardial infarctions were registered. Thus, a negative test is compatible with low disease activity and/or efficacy of calcium antagonist treatment. Further, the test may reveal a subclinical tendency to coronary artery spasm.

Myocardial catecholamines and their biosynthetic enzymes in various human heart diseases

Myocardial noradrenaline (NA) content, together with the activities of the enzymes tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) was measured in biopsy specimens taken during cardiac surgery from patients with various heart diseases. Fluorescence histochemical studies were also performed on comparable specimens. The mean NA content in patients with symptomatic ischaemic heart disease (IHD) was significantly higher than that in patients with valvular heart disease (VHD), atrial septal defect (ASD) or congestive heart failure (CHF). The lowest mean NA content was found in patients with CHF. The activities of TH and DBH were highest in the IHD group, although the differences between IHD and VHD groups were not significant. Histochemical investigations of adrenergic structures showed less fluorescence intensity in the CHF than in the other 3 groups. On the other hand, the density of the adrenergic nerve net and the size and number of varicosities were greatest in patients suffering from IHD. The significance of these results is discussed in relation to the pathophysiological mechanisms underlying these various disease conditions. In IHD the high myocardial NA content creates local conditions for excessive NA release into the myocardial interstitium at the onset of ischaemia, which is known to result in several adverse local consequences.

Favourable long term prognosis in stable angina pectoris: an extended follow up of the angina prognosis study in Stockholm (APSIS)

OBJECTIVE

To evaluate the long term prognosis of patients with stable angina pectoris.

DESIGN

Registry based follow up (median 9.1 years) of patients participating in the APSIS (angina prognosis study in Stockholm), which was a double blind, single centre trial of antianginal drug treatment.

PATIENTS

809 patients (31% women) with stable angina pectoris < 70 (mean (SD) 59 (7) years at inclusion) and an age and sex matched reference population from the same catchment area.

INTERVENTIONS

Double blind treatment with metoprolol or verapamil during 3.4 years (median), followed by referral for usual care with open treatment.

MAIN OUTCOME MEASURES

Cardiovascular (CV) death and non-fatal myocardial infarction (MI) in the APSIS cohort and total mortality in comparison with reference subjects.

RESULTS

123 patients died (41 MI, 36 other CV causes) and 72 had non-fatal MI. Mortality (19% v 6%, p < 0.001) and fatal MI (6.6% v 1.6%, p < 0.001) were increased among male compared with female patients. Diabetes, previous MI, hypertension, and male sex independently predicted CV mortality (p < 0.001). Diabetes greatly increased the risk in a small subgroup of female patients. Male patients had higher mortality than men in the reference population during the first three years (cumulative absolute difference 3.8%) but apparently not thereafter. Female patients had similar mortality to women in the reference population throughout the 9.1 years of observation.

CONCLUSIONS

Female patients with stable angina had similar mortality to matched female reference subjects but male patients had an increased risk. Diabetes, previous MI, hypertension, and male sex were strong risk factors for CV death or MI.

Postmenopausal women and cardiovascular risk: impact of hormone replacement therapy

The increased life expectancy of women living in industrialized countries is associated with an increase in diseases dependent or facilitated by a state of estrogen deficiency, such as cardiovascular and cerebrovascular diseases. Several studies have shown that estrogen replacement therapy reduces the occurrence of coronary and, perhaps, of cerebrovascular disease by nearly 50% in treated women compared with nonusers. These findings are supported by the evidence that estrogens have a beneficial effect on cholesterol metabolism and deposition, with contribution to the inhibition of atherosclerotic plaque formation in arterial walls and a direct effect on the vessel wall. In some cases, progestins may counteract the beneficial effect of estrogens on cardiovascular functions. More androgenic progestins may have a detrimental effect on vascular reactivity, whereas less androgenic progestins do not seem to reduce the beneficial effect of estrogens. Case-control and cohort studies have shown that estrogen progestin therapy is associated with a significant reduction in cardiovascular mortality and morbidity. The HERS study has added critical data about the cardioprotective effect of hormone replacement therapy in elderly women with proven coronary artery disease. However, HERS results are not applicable to the population of women commonly prescribed hormone replacement therapy, because the data have been gathered in a population of patients infrequently prescribed with this therapy. Large-scale, randomized studies are evaluating the effect of estrogen and estrogen-progestin replacement therapy on cardiovascular events in less compromised menopausal women. Until completion of these studies, hormone replacement therapy in women with increased cardiovascular risk should be viewed with neither enthusiasm nor fear.

How progestins influence the cardiovascular effect of hormone replacement therapy

Hormone replacement therapy aims to protect against osteoporosis and alleviate fastidious menopausal symptoms such as hot flushes, depression, sleep disturbances and vaginal dryness. In view of the acknowledgement of estrogen deficiency as a major trigger for the acceleration of cardiovascular risk after menopause, hormone replacement therapy may also be proposed as a substantial beneficial cardioprotective agent. The effects of progestins on lipoprotein profile and vasomotor tone are dependent on the chemical structure and the scheme of administration of progestins, with androgenic progestins and cyclical therapy having a potential detrimental effect. Prospective primary and secondary prevention studies, however, suggest that the adjunct of non-androgenic progestins to estrogen therapy is at least as effective as estrogen replacement therapy in reducing cardiovascular mortality and morbidity. Data from recent randomized secondary prevention studies have to be viewed with caution.

Acute myocardial infarction with simultaneous occlusions of two major coronary arteries in a young man

Simultaneous formation of the thrombi in two different coronary arteries is a very rare event. We present a 34-year-old man with acute myocardial infarction due to simultaneous occlusion of the two major coronary arteries. His only risk factor was smoking 40 cigarettes daily. Emergency arteriography revealed a total occlusion of the proximal left anterior descending artery (LAD) and the left circumflex coronary artery (LCx). We performed primary angioplasty to the LAD and instituted thrombolytic therapy to the LCx. During intra-aortic balloon pumping and medical treatment, the patient had no symptoms of angina. He underwent a second catheterization 4 weeks after primary angioplasty. After intravenous ergonovine provocation, coronary arteriography revealed diffuse vasospasm of the LAD and the LCx. These data suggest that habitual heavy smoking and coronary spasm may have been causatory factors for myocardial infarction in this case.

Comparative studies on the inhibitory effects of calcium antagonists on cytosolic Ca2+ levels increased by high-potassium or glutamate in cultured rat cerebellar granule cells

The inhibitory effects of calcium antagonists on high-potassium or glutamate (Glu) enhanced intracellular calcium ion ([Ca2+]i) levels were studied in cultured cerebellar granule cells. Dosages between 0.5 and 10 microM of flunarizine, nicardipine, SM6586 and SM12565 reduced the rise in [Ca2+]i induced by 50 mM KCl in a dose-dependent manner, although diltiazem, verapamil and nifedipine showed less effects on such [Ca2+]i increases. SM6586, SM12565 and flunarizine at dosages below 10 microM each reduced the magnitude of the [Ca2+]i increase induced by 25 microM Glu, but the other examined calcium antagonists were less effective. These results suggest the dissimilar efficacy of calcium antagonists on the inhibition of [Ca2+]i levels increased by high-potassium and Glu.

Self-report of chest pain symptoms and coronary artery disease in patients undergoing angiography

The relation of self-reported chest discomfort to the presence of atherosclerosis was examined, taking age and gender differences into account. Sixteen practicing cardiologists independently rated the items of a self-report questionnaire of angina pectoris (AP) symptoms according to their adjudged likelihood of being associated with coronary artery disease (CAD). Inpatients' (130 male and 82 female) responses to this questionnaire were obtained on the day prior to coronary angiography and scored according to their reporting of 12 symptoms endorsed by all 16 cardiologists, 25 symptoms endorsed by at least 90% of the cardiologists, and responses to items used in the Rose questionnaire, a brief survey tool for diagnosis of chest pain. Finally, patients' angiographic results were rated for presence of 75% or more CAD of one or more coronary arteries. Surprisingly, more symptoms were reported by patients without significant CAD, regardless of age or gender.

Thrombolysis in unstable angina: results of clinical studies

Ample evidence exists to support the major role of intracoronary thrombosis superimposed on a disrupted plaque in unstable angina. Consequently, thrombolytic treatment, already established to be highly beneficial in patients with acute myocardial infarction, might also be indicated in patients with unstable angina. The clinical response to thrombolytic treatment has been evaluated in several small-sized studies with inconsistent and somewhat deceiving results. Thus, the role of thrombolysis in the treatment of unstable angina is still controversial. Two ongoing large-scale, randomized, controlled trials, the Third Thrombolysis in Myocardial Infarction (TIMI III) in the United States testing recombinant tissue-type plasminogen activator and UNASEM in Europe testing anisoylated plasminogen-streptokinase activator complex will, it is hoped, solve the debate. At present, early thrombolysis might be considered for the treatment of the subset of patients with severe rest angina associated with transient ST-T ischemic changes.

Coronary vasospasm as a potential cause of myocardial infarction and paroxysmal atrial fibrillation in a relatively young woman

Vasospasm-related myocardial infarction in young women with normal coronary arteries has infrequently been reported and vasospasm-related paroxysmal atrial fibrillation (PAF) has rarely been described. We present a 33-year-old woman with old inferior myocardial infarction and postinfarction angina at rest; the angina was accompanied by PAF and electrocardiographic ST-segment elevation in the inferior leads. Coronary angiography revealed normal coronary arteries and intracoronary acetylcholine provoked an intense and diffuse spasm of the right and left coronary artery. The spasm of the right coronary artery was associated with PAF and ST-segment elevation in the inferior leads. Frequently documented PAF, accompanied by chest discomfort and ST-segment elevation in the inferior leads, was more effectively removed with isosorbide dinitrate than with disopyramide. These data suggest that coronary vasospasm is a likely cause of myocardial infarction and even PAF, although the precise mechanism leading to PAF remains unknown.

Spontaneous myocardial ischemia and the signal-averaged electrocardiogram

The effects of transient myocardial ischemia on the signal-averaged electrocardiogram were investigated in 13 patients with coronary artery disease and spontaneous angina undergoing 3-channel ambulatory electrocardiography. Ischemia was seen as ST elevation in 2 patients or ST depression in 11; it was anterior in 5 patients, inferior in 4 and undefined in 4. Signal-averaged electrocardiograms with noise levels less than or equal to 1 microV were obtained from Holter tapes during 54 of 61 ischemic attacks recorded in the study group (88%), and compared with 54 tracings recorded within 60 minutes of the index attacks. Baseline tracings were normal in 8 patients (62%), showed a long QRS duration in 2 (15%), and both a long QRS duration and a late potential in the remaining 3 (23%). Comparison of recordings at baseline and during ischemic attacks revealed no significant changes in signal-averaged electrocardiographic parameters. Absence of significant differences was also noted when analysis was performed according to the type of ischemic attacks (associated with ST elevation [n = 14] or ST depression [n = 40]), their location (anterior [n = 21] or inferior [n = 23]), their duration (greater than 10 minutes [n = 29] or less than or equal to 10 minutes [n = 25]), and their magnitude (greater than 2 mm [n = 18] or less than or equal to 2 mm [n = 36]). It is concluded that spontaneous transient myocardial ischemia, independent of its type, location, duration and magnitude, does not generate a substrate for late potentials on the signal-averaged electrocardiogram.

Endothelin-1, -2 and -3 directly and big-endothelin-1 indirectly elicit an abdominal constriction response in mice

When injected intraperitoneally into mice, endothelins ET-1, ET-2, ET-3 and big-endothelin-1[1-38] (big-ET-1[1-38]) produced a dose-related, robust and easily quantified abdominal constriction response within 20 min. The ED50 values for this response were 0.026, 0.005, 0.131, and 0.043 mg/kg, respectively. Hence, this test could provide a convenient in vivo endpoint for endothelin activity. The results also imply that ET-1, ET-2, ET 3 or big-ET-1[1-38] may be nociceptive under certain conditions. Morphine (4 mg/kg, s.c.) administered 30 min prior completely blocked the response produced by ET-1. Thus, in conjunction with other indicators, the test may also serve as an in vivo screen for agents useful in the treatment of abdominal or visceral pain. The effect of big-ET-1[1-38], but not ET-1, was blocked by pretreatment with the enzyme inhibitor phosphoramidon (10 mg/kg, s.c., 30 min prior), implying that the big-ET-1[1-38] must first be enzymatically cleaved, presumably to ET-1, in order to elicit the abdominal constriction response. This test might also serve as a discriminative antinociceptive screen, because the response to ET-1 was not blocked by acetaminophen (400 mg/kg, p.o.), ibuprofen (75 mg/kg, p.o.) or indomethacin (1.0 mg/kg, p.o.).

Unstable angina pectoris

The pathophysiology of unstable angina has been better elucidated in the past five years and has led to more rational therapy. Coronary arteries in patients with unstable angina have atherosclerotic plaques which are often complex and are the site of platelet activation and fibrin deposition. Nitrates, one of the oldest therapies, are efficacious and act not only by dilating coronary vessels but by reducing preload and afterload. Beta blockers have a salutary effect by decreasing myocardial oxygen demand. Calcium channel blockers attenuate smooth muscle contraction and thereby act to decrease coronary artery spasm. Beta blockers and calcium channel blockers are equally efficacious in unstable angina. The antiplatelet agent, aspirin, has been shown to reduce fatal or non-fatal myocardial infarction and probably overall mortality. The use of heparin acutely for unstable angina has been demonstrated to decrease refractory angina and myocardial infarction, and acutely is probably better than aspirin. For patients with reduced ejection fractions (0.30-0.49), a prospective randomized trial has shown that coronary artery bypass graft surgery offers an improved three-year survival compared with medical therapy; however, surgery does not prevent myocardial infarction. Percutaneous transluminal coronary angioplasty may be a reasonable therapeutic alternative for some patients with single-vessel disease who are refractory to medical therapy but there are as yet no controlled trials of this question. To date a clinical benefit from thrombolytic therapy has not been demonstrated.

Preventive strategies in management of acute myocardial infarction

Recent studies on pathogenetic mechanisms, supplemented by findings in clinical trials point the way to a logical approach to acute evolving myocardial infarction. This is designed in the earliest stage to limit infarction through reduction in myocardial oxygen demands, improvement in collateral blood supply and dissolution of coronary thrombus, to prevent in a later stage coronary reocclusion through administration of antiplatelet agents, and then to prevent infarct expansion through reduction in ventricular wall tension throughout the period of repair. Application of such an approach holds the promise of reducing infarct size and all the complications of infarction, as well as short and long-term mortality. The approach is active and aggressive, and contrasts with the approach applied a decade ago, where infarction was accepted as inevitable and therapies were reserved for managing its complications.

Lack of correlation between transient myocardial ischemia and late potentials on the signal-averaged electrocardiogram

The relation between transient myocardial ischemia and late potentials was investigated in 100 patients with coronary artery disease who underwent serial recordings of the signal-averaged electrocardiogram before, during and after dipyridamole infusion. During this test, 47 patients (group 1) developed transient myocardial ischemia (with ST elevation in 14 cases and ST depression in 33), whereas 53 patients (group 2) did not. Baseline signal-averaged electrocardiogram was abnormal in 20 patients (20%): a QRS duration greater than 115 ms was seen in 6 patients, a late potential (root mean square voltage of last 40 ms of QRS [RMS40] less than 25 microV) in 9, both abnormalities in 5, with no significant differences between groups 1 and 2 (26 vs 15%, respectively). In both groups, comparison of recordings obtained before, during and after dipyridamole test revealed no significant changes in QRS duration and RMS40. Absence of significant differences was also observed when patients with transient ischemic ST elevation or ST depression were examined separately. During the test, 100% of abnormal basal recordings remained abnormal and 98% of normal recordings remained within normal limits. In only 2 patients (from group 1) RMS40, which showed borderline values at baseline, decreased to abnormal values during dipyridamole test. These data suggest that electrophysiologic abnormalities induced by transient myocardial ischemia may not bear any relation with the substrate for chronic reentrant ventricular tachyarrhythmias, as reflected by late potentials on the signal-averaged electrocardiogram.

Endothelin: a potent vasoconstrictor associated with coronary vasospasm

Endothelin, administered into the coronary arteries of anesthetized dogs, produced a profound and long-lasting reduction in coronary blood flow with electrocardiographical evidence of myocardial ischemia. Coronary angiography revealed delayed filling of the distal branches and, in some cases, cessation of the blood flow distal to the epicardial portions of coronary arteries. The coronary vasoconstriction induced by endothelin subsided after intracoronary administration of nitroglycerin. Pretreatment with the Ca2+-channel antagonist, nitrendipine, suppressed endothelin-induced vasoconstriction. These findings suggest that endothelin, produced by vascular endothelial cells, may contribute to the pathogenesis of coronary vasospasm.

Superior mesenteric artery vasoactivity in hyperlipidemic Watanabe rabbits versus normal lipidemic New Zealand controls

Recent in vitro studies on isolated coronary and mesenteric arteries have shown that hyperlipidemia appears to hypersensitize the vascular arterial smooth muscle to drugs such as ergonovine and that this increased contractility seems to be mediated by a serotinergic mechanism. This results in vasospasm with exposure to certain vasoactive drugs such as serotonin or norepinephrine. However, in vivo quantification of this observed phenomenon has not been done. In the present study we used Watanabe hereditary hyperlipidemic (WHHL) rabbits (cholesterol level 459 +/- 216 mg/dL) and the normal lipidemic New Zealand white (NZW) rabbit (cholesterol level 35 +/- 19) as a control in the study of hyperlipidemia and blood flow changes in response to various vasoactive drugs. Blood flow measurements were made by the video dilution technique (VDT) following catheterization of the superior mesenteric artery. The serotinergic vasoactive drug ergonovine maleate was injected into the superior mesenteric artery at low dose (0.002) mg/kg) and high dose (0.004 mg/kg). A significant decrease (p less than .05) in blood flow was observed in response to high-dose ergonovine maleate in WHHL rabbits compared to the NZW rabbits. This in vivo experiment confirms the in vitro studies showing that hyperlipidemia sensitizes mesenteric arteries in the presence of serotinergic stimuli. The vasodilators verapamil hydrochloride and calcitonin gene-related peptide (CGRP) injected into the superior mesenteric artery caused a marked increase in flow in both the WHHL and the normal lipidemic NZW rabbits. This model can be used in the assessment of superior mesenteric artery ischemia and its reversal.

Unstable angina: current concepts of medical management

Unstable angina describes a clinical syndrome bridging the gap between stable angina and acute myocardial infarction. By definition, patients with angina of new onset, of a crescendo pattern, and with angina at rest are included in this high-risk group. The underlying pathogenetic mechanisms are complex and include initial atherosclerotic plaque rupture, release of vasoactive substances, and intracoronary thrombus formation. The currently established medical approach of the acute phase consists of heparin for anticoagulation and nitrates combined with beta-blockers for the relief of pain. Calcium antagonists are indicated, if anginal symptoms persist. The effect of thrombolytic therapy is still under investigation. Angina refractory to medical treatment and angina at rest are associated with a particularly unfavorable prognosis and prompt early catheterization. The long-term prognosis of the patient is markedly improved by chronic platelet inhibitory treatment with aspirin.

Effects of hypercholesterolemia on the microsomal membrane fluidity of intimal-medial versus medial layers of swine aorta: implications for the pathogenesis of vasospasm

The hypothesis was examined that hypercholesterolemia induces a decrease in arterial microsomal membrane fluidity. To investigate this hypothesis, the fluorescence anisotropy (r) of 1,6-diphenylhexa-1,3,5-triene was measured in aortic microsomes isolated from the intimal-medial (IM) and medial (M) layers of swine thoracic aortas. After 10 weeks of feeding a high fat (10% lard) diet, serum cholesterol increased 2.3-fold compared to 3.6-fold in pigs fed a similar diet supplemented with 2% cholesterol. Based upon differences in r, the membrane fluidity of the IM layer was significantly less than the M layers. The membrane fluidity of the IM layer was inversely related to the severity of hypercholesterolemia regardless of dietary treatment. There were no differences in membrane fluidity among the three dissected M layers and the membrane fluidity of these layers was refractory to changes in serum cholesterol. A decrease in the membrane fluidity of the IM layer may contribute to the abnormal regulation of vascular tone which underlies the development of vasospasm in atherosclerotic arteries.

Vasoconstrictor activity of coronary sinus plasma from patients with coronary artery disease

Vasoactive properties of plasma samples taken from the coronary sinus, a systemic artery and the superior vena cava of 13 patients with angiographically proven coronary artery disease and from 5 patients with normal coronary arteriograms were assayed in vitro by measurement of the changes in tension of rings of isolated canine coronary arteries. Addition of 1 ml samples of platelet-rich plasma from the coronary sinus of patients with coronary artery disease into a 20 ml organ bath induced an initial relaxation followed by sustained constriction in bioassay coronary artery rings with endothelium and only vasoconstriction in rings without endothelium. The vasoconstrictor activity of the coronary sinus plasma showed positive correlation with the severity and extent of coronary artery narrowing. Systemic arterial and venous plasma samples from patients with coronary artery disease and the coronary sinus plasma from patients with no coronary artery disease evoked only endothelium-dependent relaxations. These vasoactive properties of the various plasma samples were similar whether the samples were taken during rest or during supine bicycle exercise. The serotoninergic receptor antagonist methiothepin prevented the vasoconstriction induced by the coronary sinus plasma samples. These data demonstrate that the coronary sinus blood of patients with atheromatous coronary artery disease exhibits vasoconstrictor activity that may be associated with 5-hydroxytryptamine (serotonin), presumably released from platelets.

Calcium channel blockers and cardiac surgery

Calcium channel blockers have an important role in the pharmacotherapy of cardiovascular disorders. These agents act by inhibiting the slow inward current into excitable cells, exert direct negative inotropic, chronotropic, and dromotropic activity, and are potent vasodilators. These direct effects are modified by reflex autonomic stimulation and by pathologic states. Serious adverse effects of the calcium channel blockers are most frequently observed in patients with ventricular dysfunction, conduction system disease, or concomitant beta blockade. Calcium channel blockers are indicated in the treatment of angina pectoris, supraventricular arrhythmias, and hypertension. The use of these agents in patients with hypertrophic cardiomyopathy, congestive heart failure, and pulmonary hypertension is investigational. The calcium channel blockers are gaining increased importance in the management of patients undergoing cardiac surgery. Verapamil is indicated for the treatment of post-cardiac-surgical atrial flutter and fibrillation; however, the calcium antagonists are not effective as prophylaxis against postoperative supraventricular arrhythmias. Laboratory studies have shown that drug interactions exist between calcium channel blockers and inhalational anesthetics and nondepolarizing neuromuscular blocking agents; clinical studies have demonstrated that these interactions are rarely significant. Perioperative coronary spasm can be effectively treated with the calcium channel blockers. The timing of calcium antagonist withdrawal prior to surgery is controversial, but continuation of therapy until surgery is usually safe. The clinical significance of platelet function inhibition by the calcium antagonists is unknown. Protection of ischemic myocardium by calcium channel blockers has been demonstrated. Important interactions between the calcium antagonists, hypothermia, and the ionic constituents of cardioplegia require further study before the role of these agents as adjuncts to clinical cardioplegia is defined. Expanded indications and the introduction of new calcium channel blockers will result in increased use of these agents in the future.

Louis F. Bishop lecture. Role of coronary artery spasm in symptomatic and silent myocardial ischemia

The revival of the concept of coronary spasm has stimulated research into coronary artery disease. Observations in patients with variant angina have substantially contributed to the appreciation of painless myocardial ischemia. However, the presence or absence of pain during ischemic episodes is not related to the cause of ischemia, because painless ischemia can be observed in variant angina (caused by spasm), in effort-induced angina (caused by increased myocardial demand) and in myocardial infarction (caused by thrombosis). Continuous monitoring initially of patients with variant angina and subsequently of patients with unstable and stable angina proved that often painful and painless ischemic episodes are caused by a transient impairment of regional coronary blood flow rather than by an excessive increase of myocardial demand. The transient impairment of coronary flow appears to be caused by dynamic stenosis of epicardial coronary arteries. This most often occurs at the site of atherosclerotic plaques encroaching on the lumen to a variable extent. Dynamic stenosis can be caused by 1) "physiologic" increase of coronary tone, as in stable angina, 2) spasm, as in variant angina, and 3) thrombosis, usually in combination with "physiologic" changes in tone or with spasm, or both, as in unstable angina. The mechanisms of spasm, as typically observed in variant angina, are different from those of "physiologic" increase of tone; they appear to be related to a local alteration that makes a segment of coronary artery hyperreactive to a variety of constrictor stimuli causing only minor degrees of constriction in other coronary arteries. The nature of this abnormality, which may remain stable for months and years, is yet unknown.

Risk factors for angina pectoris in a population study of Swedish men

The Primary Preventive Trial in Göteborg, Sweden, a study of a random population sample of middle-aged men, made it possible to analyse the risk factor pattern cross-sectionally in 166 men with uncomplicated angina pectoris (AP) and compare with 5735 men without angina pectoris or myocardial infarction (MI). A prospective analysis was also performed concerning the risk factor pattern in 128 cases with uncomplicated AP and 34 cases with complicated AP (following an MI) respectively, appearing during a follow-up time of 4 years. At cross-sectional analysis, uncomplicated AP was related to elevated serum cholesterol, elevated systolic and diastolic blood pressure, increased relative body weight, smoking, diabetes mellitus, low physical activity during leisure time, dyspnea and mental stress. However at multivariate, prospective analysis only dyspnea, stress, diabetes mellitus and increased relative body weight were predictors for uncomplicated AP. In contrast, elevated serum cholesterol, high blood pressure, smoking, and high physical activity at work were predictors for complicated AP. Possible reasons for the apparent risk factor differences and different mechanisms in AP and MI are discussed.

Daily variations of ECG and left ventricular parameters at exercise in patients with anginal attacks but normal coronary arteriograms

In 21 patients with typical exercise-induced anginal pain but normal coronary arteriograms (group N) and in 14 patients with angiographically proved coronary stenosis (group C), symptom-limited ergometer exercise ECG and radionuclide angiocardiography were performed twice on two different days. Exercise-induced ST changes showed larger variations between the two exercise tests in group N than in group C ([delta ST1-delta ST2]: 0.07 +/- 0.06 mV in group N, 0.03 +/- 0.03 mV in group C, p less than 0.05). Rate pressure product and left ventricular ejection fraction at exercise also showed larger variations between the two tests in group N than in group C (p less than 0.001, p less than 0.05, respectively). However, substantial overlaps existed in some cases in the two groups. In conclusion, some of the patients with exercise-induced anginal pain but normal coronary arteriograms may have a variable threshold of exertional chest pain probably caused by variation in coronary vascular tone, and the other patients may have a fixed threshold of chest pain caused by other mechanisms.

Familial migraine and coronary artery spasm in two siblings

A common pathophysiology for the clinical association of variant angina and migraine has been suggested, but the pathogenesis of both illnesses is yet unknown. Our report presents two siblings with both illnesses and a familial history of migraine where coronary artery spasm was documented, spontaneously in one and after the administration of ergonovine maleate in the other one. Our study strongly supports the hypothesis that genetic factors possibly play a role in the etiology of variant angina and migraine at least in some patients.

Sudden death due to painless spasm in near normal coronary arteries

Two cases of resuscitated sudden cardiac death are described; one was due to ventricular fibrillation and the other to ventricular asystole. In both cases the underlying etiology was painless coronary spasm and no fixed coronary disease.

Rationale for calcium entry-blocking drugs in systemic hypertension complicated by coronary artery disease

There is considerable rationale for the use of the calcium entry-blocking drugs for the treatment of hypertension and prevention of recurrent episodes of angina pectoris in patients with systemic hypertension and significant coronary artery disease--the 2 entities commonly occurring together. Calcium entry-blocking drugs improve myocardial blood flow while decreasing myocardial oxygen demand. These agents can be given to most patients with ischemic heart disease and its complications, and are associated with a relatively low incidence of serious adverse effects and toxicity during long-term therapy. They reduce the frequency of anginal attacks, prolong exercise time to ST-segment depression or angina and improve exercise capacity. With long-term therapy, tolerance does not develop as it does in many patients with the "long-acting" nitrates. Calcium entry-blocking drugs reduce systolic blood pressure in patients with hypertension by a decrease in peripheral vascular resistance and a uniform improvement in blood flow affecting the myocardium, kidney and brain. There are no central nervous system adverse effects and hypokalemia does not occur. Unlike therapy with the beta-blocking drugs, chronic treatment with the calcium entry blockers does not reduce the serum level of high-density lipoprotein cholesterol nor increase serum triglyceride concentration. The calcium blockers decrease the arterial blood pressure without increasing intravascular plasma volume and are associated with only a slight increase in reflex-mediated sympathetic activity and heart rate, the latter occurring predominantly with nifedipine. Calcium entry-blocking drugs provide alternative or preferred therapy to beta-blocking agents in patients with a combination of hypertension and angina pectoris.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary hemodynamic responses during spontaneous angina in patients with and patients without coronary artery spasm

The mechanisms of spontaneous angina were evaluated during cardiac catheterization in 13 patients who had angina occurring without provocation at rest. Left ventricular and systemic hemodynamics, coronary venous flows (thermodilution technique), electrocardiogram and coronary angiograms were recorded before and during spontaneous angina. Angiography during spontaneous angina showed that 5 patients had coronary spasm (group I) and 8 patients did not (group II). In group II there was a preponderance of multivessel coronary artery disease. Left ventricular end-diastolic pressure increased in all patients in both groups during spontaneous angina. In group I, 4 patients had transient ST elevation and 1 patient had peaked T waves during angina. Transient ST depression occurred during spontaneous angina in all group II patients. Group I patients had decreased coronary sinus flow (4 of 5 patients) or decreased regional flow (5 of 5) during spontaneous angina. Coronary resistance and ratio of double product to coronary blood flow increased in all patients. In group II, coronary hemodynamic responses during spontaneous angina varied. Coronary venous flows, coronary resistance and ratio of double product to coronary blood flow showed no uniform pattern. Thus, patients with severe coronary artery disease can have spontaneous angina without angiographic findings of coronary spasm. After analysis of angiograms and coronary hemodynamics in these patients, no apparent uniform mechanism for spontaneous angina was found.

Patients with malignant or potentially malignant ventricular arrhythmias: opportunities and limitations of drug therapy in prevention of sudden death

Almost 90% of patients resuscitated from out of hospital cardiac arrest have coronary heart disease and can be categorized in one of three groups: acute myocardial infarction, ischemic event or primary arrhythmic event. The patients who have acute myocardial infarction have the best prognosis, and those with primary arrhythmic events have the worst. Recent studies show that ventricular arrhythmias after myocardial infarction are associated with mortality independent of any association with left ventricular dysfunction. Ventricular arrhythmias that have caused cardiac arrest or hemodynamic collapse, that is, malignant arrhythmias, should be treated aggressively and evaluated carefully with one of two methods that have high predictive accuracy for outcome: 1) the Holter recording/exercise test approach, or 2) the electrophysiologic approach. It is not yet known whether treating potentially malignant ventricular arrhythmias after myocardial infarction with class I or III antiarrhythmic drugs will reduce mortality, but two clinical trials are under way in the United States to address this question. Beta-adrenergic blocking drugs do reduce mortality, probably as a result of both antiischemic and antiarrhythmic effects. Calcium channel blocking agents, various antiplatelet drugs and alpha-adrenergic blocking drugs are under investigation to determine their value in secondary prevention of ventricular fibrillation.

Comparative effects of calcium-channel blocking agents on left ventricular function during acute ischemia in dogs with and without congestive heart failure

To examine the relative potencies of verapamil, nifedipine and diltiazem on left ventricular (LV) function under ischemic conditions, 20 conscious closed-chest dogs that had partial occlusion of their circumflex coronary arteries were studied. Myocardial blood flow was measured by microspheres, LV function by radionuclide angiography. Drug effects were compared at doses causing equal decreases in mean arterial pressure (MAP) and in coronary vascular resistance of the nonischemic zone. Global ejection fraction (EF) and EF of the ischemic region were significantly decreased by verapamil (p less than 0.002) and increased by nifedipine (p less than 0.001); diltiazem caused no significant changes. Verapamil significantly increased peak diastolic filling rate (p less than 0.001); nifedipine also increased diastolic filling rate but only at doses that markedly decreased MAP and coronary vascular resistance. Diltiazem was not significantly different from placebo. For doses causing an equal decrease in MAP, verapamil decreased heart rate (p less than 0.001), and diltiazem and nifedipine increased heart rate (p less than 0.05). Myocardial ischemic zone flow remained unchanged during placebo, verapamil, diltiazem or nifedipine infusion. To study the influence of heart failure on the hemodynamic effects of the calcium-channel blocking agents, 6 foxhounds underwent total occlusions of the left anterior descending coronary artery, resulting in myocardial infarction, volume loading to increase left atrial pressure and partial occlusion of the circumflex coronary artery. Verapamil depressed global left ventricular ejection fraction and increased left atrial pressure to as high as 40 to 45 mm Hg. In contrast, nifedipine decreased left atrial pressure and increased global EF.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium antagonists for acute ischemic heart disease

The pharmacologic and physiologic effects of the slow-channel calcium antagonists verapamil, nifedipine and diltiazem are reviewed. Relevant pathophysiologic features of various acute ischemic heart disease syndromes are also reviewed and the clinical applications of the slow-channel calcium antagonists to acute ischemic heart disease syndromes in patients are discussed.

Inhibitors of prostaglandin synthesis augment beta-adrenergic responsiveness in canine coronary arteries

The effects of inhibition of endogenous prostaglandin synthesis on the release of norepinephrine from sympathetic nerves and on postjunctional adrenergic responsiveness were studied in isolated canine left circumflex coronary arteries. In rings, suspended for isometric tension recording and contracted with prostaglandin F2 alpha, transmural electrical stimulation caused frequency-dependent relaxations, which were blocked by propranolol and augmented by indomethacin. In superfused strips, previously incubated with [3H]norepinephrine, electrical stimulation (2 Hz) increased the overflow of tritiated neurotransmitter; indomethacin did not influence basal or evoked [3H]norepinephrine overflow. Exogenous norepinephrine caused relaxations in rings contracted with prostaglandin F2 alpha, but increases in tension in potassium-depolarized tissues which could be abolished by phentolamine; isoproterenol induced relaxations in both cases. Indomethacin significantly augmented the relaxation in response to exogenous norepinephrine (during contractions with prostaglandin F2 alpha) and reversed norepinephrine-induced contractions (during potassium-depolarization) into relaxation. Other cyclooxygenase inhibitors had comparable effects. In the presence of propranolol, indomethacin did not diminish contractions evoked by norepinephrine in depolarized rings. Relaxations induced by sodium nitroprusside or acetylcholine during contractions caused by prostaglandin F2 alpha or potassium chloride were not affected by indomethacin. The augmentation of beta-adrenergic responsiveness by indomethacin was abolished by exogenous prostacyclin. The prostacyclin synthetase inhibitor tranylcypromine and exogenous prostaglandin E2 depressed beta-adrenergic responsiveness. Indomethacin did not affect the facilitatory action of phosphodiesterase inhibition on beta-adrenergic relaxation. The data suggest that endogenous prostaglandins (most probably prostacyclin and prostaglandin E2) exert a "braking" effect on beta-adrenergic responsiveness in coronary arterial smooth muscle.