Pathophysiology of Cardiac Pain

Neuromodulation in patients with refractory angina pectoris: a review

The number of patients with coronary artery disease (CAD) who have persisting angina pectoris despite optimal medical treatment known as refractory angina pectoris (RAP) is growing. Current estimates indicate that 5-10% of patients with stable CAD have RAP. In absolute numbers, there are 50 000-100 000 new cases of RAP each year in the USA and 30 000-50 000 new cases each year in Europe. The term RAP was formulated in 2002. RAP is defined as a chronic disease (more than 3 months) characterized by diffuse CAD in the presence of proven ischaemia which is not amendable to a combination of medical therapy, angioplasty, or coronary bypass surgery. There are currently few treatment options for patients with RAP. One such last-resort treatment option is spinal cord stimulation (SCS) with a Class of recommendation IIB, level of evidence B in the 2019 European Society of Cardiology guidelines for the diagnosis and management of chronic coronary syndromes. The aim of this review is to give an overview of neuromodulation as treatment modality for patients with RAP. A comprehensive overview is given on the history, proposed mechanism of action, safety, efficacy, and current use of SCS.

Theranostic Nanomedicines for the Treatment of Cardiovascular and Related Diseases: Current Strategies and Future Perspectives

Cardiovascular and related diseases (CVRDs) are among the most prevalent chronic diseases in the 21st century, with a high mortality rate. This review summarizes the various nanomedicines for diagnostic and therapeutic applications in CVRDs, including nanomedicine for angina pectoris, myocarditis, myocardial infarction, pericardial disorder, thrombosis, atherosclerosis, hyperlipidemia, hypertension, pulmonary arterial hypertension and stroke. Theranostic nanomedicines can prolong systemic circulation, escape from the host defense system, and deliver theranostic agents to the targeted site for imaging and therapy at a cellular and molecular level. Presently, discrete non-invasive and non-surgical theranostic methodologies are such an advancement modality capable of targeted diagnosis and therapy and have better efficacy with fewer side effects than conventional medicine. Additionally, we have presented the recent updates on nanomedicine in clinical trials, targeted nanomedicine and its translational challenges for CVRDs. Theranostic nanomedicine acts as a bridge towards CVRDs amelioration and its management.

Controlling Reperfusion Injury With Controlled Reperfusion: Historical Perspectives and New Paradigms

Cardiac reperfusion injury is a well-established outcome following treatment of acute myocardial infarction and other types of ischemic heart conditions. Numerous cardioprotection protocols and therapies have been pursued with success in pre-clinical models. Unfortunately, there has been lack of successful large-scale clinical translation, perhaps in part due to the multiple pathways that reperfusion can contribute to cell death. The search continues for new cardioprotection protocols based on what has been learned from past results. One class of cardioprotection protocols that remain under active investigation is that of controlled reperfusion. This class consists of those approaches that modify, in a controlled manner, the content of the reperfusate or the mechanical properties of the reperfusate (e.g., pressure and flow). This review article first provides a basic overview of the primary pathways to cell death that have the potential to be addressed by various forms of controlled reperfusion, including no-reflow phenomenon, ion imbalances (particularly calcium overload), and oxidative stress. Descriptions of various controlled reperfusion approaches are described, along with summaries of both mechanistic and outcome-oriented studies at the pre-clinical and clinical phases. This review will constrain itself to approaches that modify endogenously-occurring blood components. These approaches include ischemic postconditioning, gentle reperfusion, controlled hypoxic reperfusion, controlled hyperoxic reperfusion, controlled acidotic reperfusion, and controlled ionic reperfusion. This review concludes with a discussion of the limitations of past approaches and how they point to potential directions of investigation for the future.

Clinical course and symptomatology of angina pectoris in a population study

The clinical course of angina pectoris was studied in a follow-up study of 427 patients with angina from a general population sample. The subjects were men aged 56-65 years at the time of follow-up. After a mean follow-up time of 5.8 years, 55% were still suffering from angina pectoris, 15% had died and a further 19% were either free from chest pain or had chest pain considered to be of different origin. In the group with definite angina pectoris at follow-up (n = 236), 29% had sustained a myocardial infarction, 23% had symptoms of intermittent claudication, 36% were treated for hypertension and 15% had diabetes. Many of the angina patients suffered from other chest conditions in addition to anginal symptoms. Most of the patients (56%) had infrequent attacks (a few times per month or less often) and were not severely incapacitated by their symptoms. Only one fifth worked full time compared with more than half of those in the same age groups in the general population. Only 16 of those interviewed had undergone bypass surgery and a further 16 had disabling angina but, for various reasons, they had not been operated on. The implications are that most angina patients do well on pharmacological treatment alone even though they are limited socially as well as physically. Precipitating factors other than physical activity were also investigated and associations were found between susceptibility to cold, early morning angina, angina at rest and attacks of long duration, possibly indicating a mechanism of vasospasm superimposed on a fixed stenosis.

Effect of raised plasma beta endorphin concentrations on peripheral pain and angina thresholds in patients with stable angina

OBJECTIVE

To determine whether changes in plasma concentrations of beta endorphins alter angina threshold and peripheral pain threshold in patients with stable angina.

DESIGN

Latin square design comparison of angina thresholds by exercise treadmill test and peripheral pain thresholds using a radiant heat source in eight patients with stable angina under control conditions, after stimulation of pituitary beta endorphin release by ketoconazole, after suppression of pituitary beta endorphin release by dexamethasone, and after blockade of opioid receptors by intravenous naloxone.

RESULTS

An approximately fivefold increase in circulating concentrations of beta endorphins was found after administration of ketoconazole (mean (SEM): 13.9 (1.2) v 73.8 (6.2) pg/ml; p < 0.05), which was associated with an increase in peripheral pain threshold to a radiant heat source (time to onset of pain perception 72 (19) v 123 (40) seconds; p < 0.05), but no significant difference in angina threshold. A reduction in circulating concentrations of beta endorphins after pretreatment with dexamethasone was statistically non-significant (13.9 (1.2) v 9.0 (1.5) pg/ml; NS) and was not associated with any change in either peripheral pain or angina thresholds. No effects were seen after blockade of opioid receptors by previous administration of intravenous naloxone.

CONCLUSIONS

Increased plasma concentrations of beta endorphins alter peripheral pain threshold but not angina threshold in patients with stable angina pectoris.

Role of respiratory sleep disorders in the pathogenesis of nocturnal angina and arrhythmias

This report documents how respiratory sleep disorders can adversely effect ischaemic heart disease. Three male patients (aged 60-67 years) with proven ischaemic heart disease are described. They illustrate a spectrum of nocturnal cardiac dysfunction, two with nocturnal angina and one with nocturnal arrhythmias. Full sleep studies were performed in a dedicated sleep laboratory on all patients, and one patient had 48 hours of continuous Holter monitoring. Two patients were found to have obstructive sleep apnoea with apnoea/hypopnoea indices of 57 and 36 per hour, respectively, the former with nocturnal arrhythmias and the latter with nocturnal angina. In both cases, nasal continuous positive airways pressure successfully treated the sleep apnoea, with an associated improvement in nocturnal arrhythmias and angina. The third patient who presented with nocturnal angina, did not demonstrate obstructive sleep apnoea (apnoea/hypopnoea index = 7.2) but had significant oxygen desaturation during rapid eye movement (REM) sleep. This patient responded to a combination of nocturnal oxygen and protriptyline, an agent known to suppress REM sleep, and had no further nocturnal angina. All patients were considered to be an optimum cardiac medication and successful symptom resolution only occurred with the addition of specific therapy aimed at their sleep-related respiratory problem. We conclude that all patients with nocturnal angina or arrhythmias should have respiratory sleep abnormalities considered in their assessment.

Correlation between myocardial ischemia and changes in arterial resistance during coronary artery bypass surgery

The arterial resistometer provides continuous on-line monitoring of changes in arterial resistance. Resistance index (Ri), which bears a direct relationship to systemic vascular resistance (SVR), is defined by the equation Ri = P'/(dP'/dt), where dP'/dt is the peak dP/dt of the arterial waveform, and P' is the pressure at dP'/dt. In 42 patients with unstable angina, changes in Ri were studied at six periods during aortocoronary bypass surgery before tracheal intubation, during tracheal intubation, leg elevation, presternotomy, sternotomy, and dissection of the internal mammary artery. Thirty-four episodes of ischemia (0.1 mV ST segment changes) were observed in 26 patients. All ischemic episodes were associated with increased Ri (mean increase, 102 +/- 52%). Elevation of the pulmonary capillary wedge pressure correlated with ischemia during the preintubation, intubation, and sternotomy periods, but not in the remaining periods. Changes in arterial pressure and heart rate were not good predictors of ischemia. The prevalence of ST segment changes increased markedly during all periods of anesthesia with increase in Ri (P less than 0.05). Ninety-one percent of ST segment changes were associated with a 25% increase from the baseline Ri. Raising the cutoff point to a greater than or equal to 75% increase in Ri improved the specificity of Ri in ischemia detection from 61% to 92%. An increase of greater than or equal to 75% in Ri occurred in only 8% of cases without ST segment changes. It was found that an increase in Ri as depicted by the arterial resistometer was the best hemodynamic correlate of myocardial ischemia.

Prediction of degree of residual stenosis in coronary thrombolysis

In order to predict the residual stenosis in coronary thrombolysis, the factors easily obtained from clinical history--age, gender, history of angina before acute myocardial infarction (AMI), family history, hypertension, diabetes, hypercholesterolemia, smoking, and interval between onset of AMI and recanalization--were observed in 114 patients with successful coronary thrombolysis. In 55 patients with angina before AMI, 29 patients had residual stenosis greater than or equal to 75% and 26 patients had residual stenosis less than 75%. In 59 patients without angina before AMI, 15 patients had residual stenosis greater than or equal to 75%, and 44 patients had residual stenosis less than 75%. The presence or absence of angina before AMI was the main variable that discriminated the groups of residual stenosis of more or less than 75%, which was the only significant independent variable to predict the residual stenosis. These data suggest that the presence of angina pectoris before AMI is likely to be associated with a significant degree of residual stenosis after thrombolysis.

Presence of angina pectoris before acute myocardial infarction and degree of residual stenosis after coronary thrombolysis

This study tested the hypothesis that the degree of residual stenosis after coronary thrombolysis reflected that of original stenosis presented by symptom of angina before acute myocardial infarction (AMI). The relation between the presence of angina before AMI and the degree of residual stenosis after coronary thrombolysis was observed in 57 patients with successful coronary thrombolysis for AMI. Patients with significant coronary artery stenoses other than the artery responsible for AMI were excluded from this study. In 22 patients with chronic angina for 2 weeks or longer before AMI, 14 patients had a residual stenosis of 75% or more and 8 patients had a residual stenosis of less than 75%. In 35 patients with angina for less than 2 weeks or not at all before AMI, 9 patients had a residual stenosis of 75% or more, and 26 patients had a residual stenosis of less than 75% (p less than 0.01). In the course of progression of coronary artery disease, some patients had AMI without severe underlying stenosis and others with severe underlying stenosis. Patients with chronic angina before AMI might tend to have AMI with acute occlusion superimposed on the severe organic stenosis. Patients without chronic angina before AMI would be more at risk for AMI caused by acute occlusion without underlying severe stenosis.

Asymptomatic left main coronary artery disease and silent myocardial ischemia

Gathering data on the prognosis, detection, and natural history of asymptomatic left main coronary artery disease with silent myocardial ischemia is difficult. Epidemiologic studies of unexpected death and postmortem studies on silent myocardial infarction suggest this entity to be common. We reviewed 89 consecutive patients with left main coronary artery disease (LMD), defined as 50% or greater reduction of luminal diameter. Of this group, 10 patients (11%) were asymptomatic (ALMD) and 79 patients (88%) were symptomatic (SLMD). All 10 ALMD patients were men, with a mean age of 53 years (range 40 to 65). Treadmill tests (TMT) were performed for: ECG abnormalities six; pre-jogging evaluation two; risk factor evaluation two. The TMT within 9 minutes showed 2 mm or greater ST depression in seven (70%) and 1 to 2 mm in three (30%). Similar TMT results were obtained in the SLMD group, although two patients had negative responses. The degree of stenosis of the left main coronary artery and the frequency of three-vessel disease were similar in both groups. The ejection fraction (EF) and contractile pattern of the left ventricle (LV) were normal in all 10 ALMD patients, but the left ventricular end-diastolic pressure (LVEDP) was abnormal in three (70%). In the SLMD group, 51 (64%) had an abnormal ejection fraction, 50 (65%) had wall motion abnormalities, and 25 (32%) had an abnormal LVEDP.

Relationship between location of chest pain and site of coronary artery occlusion

Chest pain characteristics and site of coronary artery occlusion were evaluated in 148 patients having single-vessel coronary angioplasty and in 95 patients having double-vessel angioplasty. The locations of chest pain included substernal and left precordium, right precordium and epigastric. The possible sites of pain radiation were limited to neck/jaw, left arm, right arm, and interscapular. The patient described whether or not the pain was typical of previous angina, and the presence of ST segment deviation was noted to be certain that ischemia was present. The analysis showed that the occluded artery could not be reliably identified. However, it was possible to say which artery was most likely not diseased. Patients presenting with substernal or left chest pain with radiation to the left arm had a less than 10% chance of having right coronary artery disease. A patient presenting with epigastric pain radiating to the neck or jaw had a less than 13% chance of having left anterior descending disease. It is concluded that in patients with single- and double-vessel coronary disease, there is some relationship between chest pain pattern and disease location.

Mandibular pain as the initial and sole clinical manifestation of coronary insufficiency: report of case

A case of anginal pain limited to the mandible with secondary radiation of the pain to the neck and clavicular regions is presented. Although the pain was initially diagnosed as odontogenic in origin, further historical workup suggested the suspicion of referred pain from coronary insufficiency. Immediate cardiac evaluation confirmed the nature of the pain as angina. Important aspects involved with differential diagnosis of referred anginal pain are also discussed.

Aortic distensibility abnormalities in coronary artery disease

Vasodilatory capacity of nonstenotic arteries in experimental animals with atherosclerosis is decreased. It was postulated that aortic distensibility may be abnormal in patients with coronary artery disease (CAD). Aortic distensibility was determined in 24 normotensive patients with CAD and an angiographically normal aorta and values were compared with those in 18 age-matched normal subjects. Aortic diameters were measured at 3 levels--2, 4 and 6 cm above the aortic valve--by angiographic techniques. The area of the first 6 cm of the aorta above the aortic valve was planimetered and mean aortic diameters were calculated. Distensibility was calculated using the formula: [2 X (changes of the aortic diameter)/(diastolic aortic diameter) X (changes of the aortic pressure)]. CAD patients had similar aortic pressures but markedly lower distensibility than normal subjects: 0.7 +/- 0.2 vs 1.7 +/- 0.3 (p less than 0.02); 1.5 +/- 0.3 vs 4.0 +/- 0.6 (p less than 0.02); and 1.2 +/- 0.2 vs 5.3 +/- 0.6 (p less than 0.001) at 2, 4 and 6 cm above the aortic valve, respectively. Distensibility was also calculated from the mean aortic diameters and was greater in normal subjects than in CAD patients (3.4 +/- 0.4 vs 1.6 +/- 0.1, p less than 0.001). Decreased aortic distensibility in CAD may be related to the common atherosclerotic process or to reduced ascending aorta vasa vasorum flow from coronary arteries.

Unstable angina pectoris: the first half century: natural history, pathophysiology, and treatment

Unstable angina pectoris as a distinct syndrome intermediate between chronic stable angina and acute myocardial infarction was first described about a half century ago. The incidence of death or myocardial infarction rises in the first few months after destabilization of angina. Hemodynamic, scintigraphic, and arteriographic studies in the last 15 years have shown that unstable angina is chiefly due to "dynamic" coronary stenoses, transient reversible limitations in coronary blood flow caused by a complex interaction between coronary vasoconstriction, transient platelet plugging, and transient thrombosis. The trigger for the onset of dynamic coronary stenoses is probably acute changes in coronary arterial morphology in or near atherosclerotic plaques making those areas more thrombogenic. A large fraction of patients with unstable angina restabilize initially with medical management. The role of beta blockers is unclear, but they may protect against development of coronary events for patients with unstable angina similar to that reported for patients with myocardial infarction. Nitrates and calcium blockers are probably superior to beta blockers in restabilization of angina, but protection against coronary events has not yet been demonstrated clearly. Further investigation is needed to distinguish the relative benefits of a two-drug (heart rate-limiting calcium blocker plus nitrates) regimen vs. a three-drug regimen including beta blocker. There is no basis for emergency coronary bypass surgery to prevent myocardial infarction or death. Urgent surgery should be limited to patients who do not stabilize readily with medical therapy. One third or more of the patients who initially restabilize with medical therapy will require coronary revascularization in the year after unstable angina because of severe angina. An antithrombotic regimen of aspirin (or possibly heparin) reduces the incidence of progression to death or myocardial infarction. Two important future directions for research should be promising: development of better antithrombotic regimens other than aspirin alone for protection against coronary events; and improved ability to distinguish the patients who initially respond to medical therapy who are at low risk for later severe angina from those at higher risk.

Mechanisms of ischemic cardiac pain and silent myocardial ischemia

The mechanisms of cardiac ischemic pain remain obscure. It is unknown whether ischemia causes cardiac pain by the release of chemical substances or by mechanical stretching. It is also unknown whether ischemia activates specific nociceptors and pain fibers or mechanoreceptors and chemoreceptors. In patients who have both painful and painless ischemic episodes, a certain minimal duration and severity of ischemia are necessary but insufficient to explain the presence of pain, since very severe ischemia of long duration can be silent. Thus, central transmission of painful stimuli and the pain perception threshold appear to play major roles in determining the presence or absence of pain. The emotional state and psychologic expectations of patients may affect their perception and threshold of pain considerably.

Course of chest pain and its relation to CK release and ST/QRS vector changes in patients with acute myocardial infarction randomized to treatment with intravenous timolol or placebo

Assessments of hourly pain scores (0 to 4) were made in 135 patients during the initial 24 hours after admission to the hospital. The duration of chest pain and the cumulative pain score obtained by adding the pain scores hour by hour were compared to ST and QRS vector changes and CK release. The cumulative pain score over a 24-hour period after admission correlated to the maximal QRS vector difference (r = 0.51) and the cumulative CK release (r = 0.58). The time until patients had complete relief of pain was closely related to the time during which QRS vector changes were seen to continue (r = 0.73). No corresponding correlation was found between pain duration and CK release time (r = 0.24). The ST decline time correlated to the duration of the first uninterrupted episode of chest pain in the placebo group only (r = 0.50). Pain duration showed no correlation to our indices of infarct size. There was a recurrence of pain in 41% of the patients, of whom 36% had a time-associated further increase of the ST vector magnitude. We conclude that chest pain is an important clinical symptom that signals ongoing necrosis. Furthermore, assessments of a "soft" parameter, such as the cumulative pain score, can add valuable information concerning the severity of myocardial damage.

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.

Angina pectoris before and during acute myocardial infarction: relation to degree of physical activity

One hundred ninety-seven patients with a history of acute myocardial infarction (AMI) were interviewed to evaluate the character of angina pectoris relative to physical activity before AMI and at the onset of AMI. Ninety-two patients had no angina before AMI and 105 had angina. Among the 105 patients with angina, 58 had chronic stable angina that did not change before AMI, 22 noted worsening of symptoms within 2 weeks before AMI, and 25 had onset of angina within 2 weeks before AMI. In the 92 patients without angina before AMI, AMI occurred during heavy exertion in 10 (11%), mild exertion in 43 (47%), at rest in 28 (30%), and during sleep in 11 (12%). In the 58 patients with chronic stable angina, 47 had angina during exertion, 7 during rest and 4 during both. However, subsequent AMI occurred during heavy exertion in 9 (15%), during mild exertion in 16 (28%), at rest in 25 (43%), and during sleep in 8 (14%). In the patients without angina, or with chronic stable angina without worsening of symptoms, AMI occurred unpredictably or differently from the mode of physical activity precipitating angina before AMI.

Coronary angiography during exercise-induced angina with ECG changes

Coronary angiography was performed at rest and during bicycle exercise immediately after the onset of angina and significant ST segment elevation or depression in the ECG. Of 11 patients, six showed significant reduction of coronary lumen diameter at the site of organic stenosis; mean values of stenosis (range) before and during exercise were 55% (25% to 88%) and 98% (89% to 100%), respectively. Five patients did not have any diameter change of the organic lesion; mean values of stenosis (range) before and during exercise were 84% (74% to 89%) and 84% (73% to 92%), respectively. Excluding the areas of these stenoses, diameters of left main coronary artery, proximal, middle, and distal left anterior descending, circumflex, and right coronary artery segments were measured before and during exercise. Diameter in each coronary artery segment during exercise was not significantly changed from that before exercise, both in the groups with and without diameter reduction. Exercise provoked a localized worsening of coronary artery stenosis without changing the diameter in the remaining artery. These findings suggest that the worsening of stenosis might be caused by a regional abnormality of the coronary artery that is not necessarily related to the degree of organic stenosis.

Mental arithmetic stress testing in patients with coronary artery disease

A mental arithmetic stress test was performed by 122 consecutive patients undergoing diagnostic coronary arteriography. Twenty-two patients showed significant ST segment abnormalities during the test (group 1). Of these patients, 20 performed a bicycle exercise test, which was positive in all of them. Seventy patients had a negative mental stress but a positive exercise test (group 2), whereas in 30 patients both tests were negative (group 3). There were no patients with a positive mental stress test and a negative exercise test. Mental stress induced a significant increase in heart rate and systolic blood pressure in the three groups of patients. Group 1 patients, however, achieved higher values of double product during mental stress and had a shorter exercise duration than group 2 and group 3 patients. The extent of coronary artery disease (CAD) was similar in groups 1 and 2, while group 3 patients had a significantly lower prevalence of two or more vessel disease. To investigate the pathogenetic mechanism of mental stress-induced myocardial ischemia, great cardiac vein flow was measured by means of the thermodilution technique in four patients with isolated left anterior descending artery disease, who showed ST segment depression in anterior leads in response to mental stress. In three patients without vasospastic angina the calculated coronary resistance decreased during mental stress, as a result of a normal vasodilatory response to the increased myocardial oxygen consumption induced by the test. By contrast, in one patient with variant angina, coronary resistance increased suggesting coronary vasoconstriction. Our findings demonstrate that mental arithmetic stress testing may induce significant ST segment abnormalities in patients with CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of nocturnal angina pectoris: importance of increased myocardial oxygen demand in patients with severe coronary artery disease

Changes in heart rate before and throughout episodes of ST-segment depression were recorded during ambulatory electrocardiographic monitoring in five patients with daytime and nocturnal resting angina and six patients with daytime angina only, who all had severe obstructive coronary disease. In 16 of 17 nocturnal episodes and in all the daytime episodes the heart rate increased before the onset of ST-segment depression. There were no significant differences in the sequence and magnitude of changes in daytime, nocturnal, painful, or painless episodes. The maximum heart rate during individual episodes preceded the maximum ST-segment depression by a mean 80.7 s and in the majority of episodes the heart rate returned to baseline before the ST segment. Thus, in severe coronary artery disease the mechanisms producing nocturnal resting ischaemia were apparently similar to those during daytime exertion; increased myocardial oxygen demand not coronary spasm seemed responsible for most of the episodes of nocturnal ischaemia.

Coronary arteriography and left ventriculography during spontaneous and exercise-induced ST segment elevation in patients with variant angina

The present study is an angiographic demonstration of coronary artery spasm during both spontaneous and exercise-induced angina in three patients with variant angina. In each case, clinical, ECG, coronary angiographic, and left ventriculographic observations were made at rest, during spontaneous angina, and during exercise-induced angina. The character of chest pain was similar during spontaneous and exercise-induced episodes. ST segment elevation was present in the anterior ECG leads during both episodes. The left anterior descending coronary artery became partially or totally obstructed during both types of attacks. When coronary spasm was demonstrated during both types of attacks, left ventriculography disclosed akinetic or dyskinetic wall motion in the area supplied by the involved artery. In those patients with reproducible exercise-induced ST segment elevation and chest pain, thallium-201 scintigraphy showed areas of reversible anteroseptal hypoperfusion. Thus in selected patients exercise-induced attacks of angina were similar to spontaneous episodes.

Dynamic vascular factors in the genesis of myocardial ischemia

While fixed atherosclerotic and thrombotic lesions have long been known to cause myocardial ischemia and cardiac pain, the various transient or dynamic events that may also cause ischemia and pain have become better understood in the past 15 years. These can be classified into two broad categories: those that cause a dynamic reduction in the caliber of the coronary arteries and those that reduce the coronary vasodilatory reserve capacity. In the first group are myocardial compression or "bridging" of an artery; coronary vasoconstriction due to frank spasm or generalized arterial hypertonus, particularly at the site of atherosclerotic lesions; reduced arterial distending pressure and platelet aggregation which may transiently occlude a diseased arterial segment. The causes of inadequate coronary vascular reserve flow capacity can be either anatomic or functional. Among the former, the increased muscle mass to blood vessel ratio occurring in myocardial hypertrophy is most important. The functional causes of limited coronary vascular reserve include diastolic transmural compression and coronary "steal," both of hemodynamic origin. In addition, arteriolar "unresponsiveness" or dysregulation caused by smoking, drugs or other unknown conditions may adversely affect coronary vascular reserve. Hence, myocardial ischemia may result from conditions that limit potential for increase in flow or from conditions that reduce flow from a preexisting level. These conditions, which are transient and dynamic in nature, may modify the threshold for ischemia, particularly in patients with fixed coronary obstructive disease.

Impairment of myocardial perfusion and function during painless myocardial ischemia

Left ventricular (or pulmonary and systemic arterial) hemodynamics were measured for a mean of 13.6 hours during continuous electrocardiographic monitoring in 14 patients admitted to the coronary care unit because of angina at rest. Of 293 episodes of transient ST segment and T wave changes identified, 247 (84%) were completely asymptomatic. Sixty-three percent of asymptomatic episodes were associated with an elevation of the left ventricular end-diastolic or pulmonary artery diastolic pressure of 5 mm Hg or more; in 15% there were smaller elevations (2 to 4 mm Hg) and in 22% there were no changes or less than a 2 mm Hg elevation of pressure. The peak contraction and relaxation dP/dt (first derivative of left ventricular pressure) were reduced to 100 mm Hg/s or more in 84 and 81% of asymptomatic episodes, respectively. Great cardiac vein oxygen saturation measured in three patients showed an increased myocardial oxygen extraction similar to that seen in painful episodes, which preceded and accompanied asymptomatic electrocardiographic changes. These results indicate that asymptomatic electrocardiographic changes represent transient myocardial ischemia. Comparison of asymptomatic and symptomatic episodes revealed that asymptomatic episodes were generally shorter (253 +/- 159 versus 674 +/- 396 seconds, probability [p] less than 0.001) and produced less impairment of left ventricular function: there were smaller elevations of left ventricular end-diastolic or pulmonary artery diastolic pressure (5.9 +/- 5.0 versus 16.5 +/- 6.9 mm Hg, p less than 0.001), and smaller reductions of peak left ventricular contraction dP/dt (252 +/- 156 versus 395 +/- 199 mm Hg/s, p less than 0.001) and relaxation dP/dt (259 +/- 191 versus 413 +/- 209 mm Hg/s, p less than 0.001). In individual patients, however, asymptomatic and symptomatic episodes of similar duration and severity were observed. The duration and severity of ischemia appear important for the genesis of anginal pain, but additional factors must be involved.

Treatment of nocturnal angina with 10 degrees reverse Trendelenburg bed position

The effect of 10 degrees reverse Trendelenburg tilt of the bed was studied in ten patients with refractory nocturnal angina on 2 consecutive nights before aortocoronary bypass surgery. For the control night the bed was placed in the semi-orthopnoeic position, and for the test night it was put in the reverse Trendelenburg position. This position significantly reduced central venous pressure, diastolic pulmonary artery pressure, the number of isosorbide dinitrate tablets taken sublingually, and the number of angina episodes per night. Reverse Trendelenburg tilt of the bed therefore seems effective for relief of nocturnal anginal pain.

Role of coronary vasospasm in the pathogenesis of myocardial ischemia and angina pectoris

Spasm, either of heart muscle or of coronary arteries, has long been postulated as a possible cause of anginal pain. Yet early necropsy observations of obstructed coronary arteries in cases of cardiac death so focused attention on the fixed obstruction as the source of myocardial ischemia that the role of vasospasm is only now becoming evident. Further, the fact that spasm most commonly occurs together with a fixed obstruction has obscured its presence and its role in producing myocardial ischemia. In classic angina, ischemia results when increased oxygen demand is placed on the heart; the variant form of angina results from a restriction in myocardial oxygen supply, frequently even at rest. The mechanisms of coronary vasospasm are unclear, although such factors as excessive alpha-adrenergic activity, imbalances in prostaglandin synthesis, and increased Ca++ entry into myocytes through alterations in pH and blood gas tensions have been implicated.

Variable threshold of angina during exercise: a clinical manifestation of some patients with vasospastic angina

Two patients complained of chest pain while at rest and during physical activities. However there seemed to be no direct relation between exertional angina and an increasing level of work performed, indicating that these patients had a variable threshold of angina during exercise. In one patient spontaneous chest pain was associated with transient S-T segment changes in precordial leads, and during coronary arteriography the administration of ergonovine induced spasm of the left anterior descending coronary artery. The other patient showed S-T segment elevation in inferior leads during an ergonovine-induced anginal attack and coronary arteriography revealed a spontaneous spasm of the right coronary artery. In both patients repeated exercise tests yielded different results, because the chest pain and S-T segment depression occurred at different work loads with large differences in heart rate-systolic blood pressure product. It is concluded that a variable threshold of angina during exercise is a clinical manifestation in some patients with vasospastic angina and is probably due to the difference in coronary arterial tone at the onset of exercise.

Exercise-induced coronary arterial spasm: angiographic demonstration, documentation of ischemia by myocardial scintigraphy and results of pharmacologic intervention

Exercise-induced coronary arterial spasm is an infrequently recognized phemonemon whose mechanism and management are not well established. In two patients with reproducible exercise-induced S-T segment elevation and angina pectoris thallium-201 scintigraphy showed areas of reversible anteroapical hypoperfusion, and gated radionuclide ventriculography revealed anteroapical hypokinesia with a decrease in left ventricular ejection fraction at peak exercise. During coronary arteriography supine exercise provoked occlusive spasm of the left anterior descending coronary artery, which at rest had only minimal plaques. Consequently, treadmill testing was performed with five different pharmacologically provoked interventions: direct vasodilatation (nitrates), alpha adrenergic blockade (phenmoxybenzamine), beta adrenergic blockade (propranolol), calcium flux blockade (verapamil), and prostaglandin inhibition (indomethacin). Exercise-induced coronary arterial spasm, manifested as S-T segment elevation and angina, was prevented by nitrates, but was not eliminated by short-term oral administration of an alpha or beta blocking agent, a calcium antagonist or a prostaglandin inhibitor. Further, beta adrenergic blockade appeared to be detrimental. Thus, this study demonstrates (1) that coronary arterial spasm may be the underlying mechanism of at least some cases of exertional angina associated with transient perfusion deficits and left ventricular dysfunction, and (2) that it may be prevented by oral nitrates.

Angiographic demonstration of different pathogenetic mechanisms in patients with spontaneous and exertional angina associated with S-T segment depression

Three patients complained of spontaneous and exertional chest pain, both associated with S-T segment depression in anterior electrocardiographic leads. In each, coronary spasm was demonstrated on coronary arteriography during a spontaneous attack of pain. Coronary arteriograms taken during exercise-induced angina did not show evidence of spastic obstruction; this suggests that exercise-induced chest pain and S-T segment depression were secondary to the increase in oxygen requirements rather than to a sudden decrease in coronary blood flow. Thus, two pathogenetic mechanisms coexisting in the same patient may cause chest pain associated with subendocardial ischemia.

Haemodynamic and electrocardiographic accompaniments of resting postprandial angina

The early postprandial changes in 10 patients with angiographically proven coronary artery disease and history of postprandial angina were studied by the continuous recording on magnetic tape of the electrocardiogram and haemodynamic variables. The significant changes 20 minutes after a meal not followed by angina included increases in cardiac index and stroke index, with a decrease in systemic vascular resistance. When angina developed after a meal, there were significant increases in mean systemic arterial blood pressure, heart rate, pulmonary capillary wedge pressure, and systemic vascular resistance with decreases in stroke index at the onset of pain rather than at the onset of ischaemic electrocardiographic abnormalities. The first haemodynamic variable to change was pulmonary capillery wedge pressure which tended to increase coincident in time with the electrocardiographic abnormalities. In all cases, postprandial angina occurred within 25 minutes after a meal. In every instance, there was little or no change in the product of heart rate and systolic arterial blood pressure at the onset of the ischaemic electrocardiographic abnormalities at a time when the pulmonary capillary wedge pressure had begun to rise. Postprandial angina, like many cases of rest angina, may rise on the basis of a primary decrease in myocardial perfusion, the nature of which is unclear but merits further investigation.

"Silent" myocardial ischemia during and after exercise testing in patients with coronary artery disease

Although many patients with coronary artery disease (CAD) have a positive exercise test without pain, the frequency and significance of this "silent" ischemia is unclear. Therefore, we studied 122 consecutive clinically stable patients with angiographically defined CAD (greater than 75 per cent luminal stenosis) and a positive exercise test. Seventy-eight patients had pain or anginal equivalent during or after a positive exercise test; 44 did not, including 32 (26 per cent) with no symptoms at all. Patients were evaluated as to age, sex, prior myocardial infarction, congestive failure, hypertension, diabetes mellitus, and digoxin or propranolol therapy--in addition to anginal symptoms before, during, or after the exercise itself. Extent of CAD, presence of collaterals, and left ventricular ejection fraction were also determined. All exercise tests were evaluated for evidence of ST-T abnormalities or prior infarction on the control ECG as well as peak heart rate during exercise and post-exercise degree of ST segment depression. There were no significant differences between patients with and without exercise-induced pain in regard to any of the clinical and angiographic features noted above, demonstrating that "silent" myocardial ischemia during or after exercise testing is not uncommon and is not readily attributable to any obvious clinical or catheterization findings. Further studies are necessary to determine if patients with evidence of "silent" myocardial ischemia are especially prone to sudden death.

Significance and treatment of nocturnal angina preceding myocardial infarction

The presence of nocturnal angina and congestive heart failure within the month prior to admission was evaluated in the 174 patients with acute myocardial infarction. Heart size was evaluated radiographically at the time of admission. Twenty-three patients (13 per cent) experienced nocturnal angina. The incidence of nocturnal angina was significantly higher in those with anterior myocardial infarction (p less than 0.005) and subendocardial infarction (p less than 0.02) when compared with patients with inferior MI. Congestive heart failure was more common prior to admission in those with nocturnal angina (9/23) as opposed to those without (3/141) (p less than 0.001). Cardiomegaly was seen in 9/23 patients with nocturnal angina and 22/141 without (p less than 0.02). We conclude that the presence of nocturnal angina in those who develop MI increases the likelihood that the infarction will be either anterior or subendocardial rather than inferior. The association of nocturnal angina and congestive heart failure to anterior myocardial infarction is probably due to more severe and probably significant left coronary artery disease.

Evaluation of evolution of myocardial infarction by serial determinations of serum creatine kinase activity

In order to investigate the relation between the release of creatine kinase (CK) in acute myocardial infarction and the evolution of infarction, the appearance functions of CK (release of CK from the heart into the circulation) were calculated by the modified method of Sobel and associates from the serial determinations of serum CK activity in 50 patients with acute myocardial infarction. The relation of the time between the onset of infarction and the peak value of the appearance function to the duration of the evolution of abnormal Q waves in 14 patients with inferior infarction and to the duration of pain in all patients was investigated. The duration of CK release from the heart averaged 37-2+/-2-4 hours and correlated well with the total CK released (R=0.665) which represents the infarct size. The mean per cent of the total CK eventually released by the time of maximum sigmaQ (sum of the amplitude of Q wave in leads II, III, and aVF) was 80-0+/-6-4 per cent and that of CK released while pain persisted was 72-0+/-3-9 per cent. These results strongly suggest that the appearance function of CK reflects the evolution of myocardial infarction.

Unstable angina pectoris

Unstable angina is a syndrome which comprises a spectrum of symptomatic manifestations of coronary artery disease which lies between stable angina pectoris and acute myocardial infarction. Patients fall into three groups: angina of recent onset (4 weeks), angina of changing pattern, and angina occurring at rest (longer than 15 minutes). The syndrome may presage acute myocardial infarction or sudden death, or may itself be the manifestation of a myocardial infarction. The pathophysiology may involve primary cardiac events or extracardiac precipitating factors, and does not appear to be the consequence of a particular anatomic pattern of coronary artery disease. Pain may occur as a result of regional reduction of coronary flow to pressure-dependent areas of myocardium during states of increased myocardial oxygen demand. Persisting ischemia leads to infarction via a series of events which may include myocardial edema formation, increased beta-sympathetic tone, and others which have been experimentally modified by interventions designed to limit infarct size. Although the incidence of acute myocardial infarction and death was high in early studies, in recent reports acute infarction occurs in under 15.5 per cent and death in under 2 per cent. Patients at high risk are those pain persists with bed rest, and those with preceding stable angina pectoris or myocardial infarction. Prognostic differences among Groups 1, 2, and 3 may exist but cannot be assessed from available studies. Studies of the management of unstable angina have generally been uncontrolled. Hospitalization, bed rest, and short- and long-acting nitrates are generally employed in Groups 2 and 3 patients and the marked reduction in myocardial infarction rates from early to recent studies tends to support these approaches. Anticoagulants are less used now than formerly. Propranolol can produce a significant reduction of myocardial oxygen consumption and may redirect coronary flow to ischemic areas. The drug has effectively controlled pain in several studies and is now widely used to manage unstable angina. Aortocoronary bypass surgery has been extensively employed but there is only one preliminary report of a controlled study available. The role of surgery is not yet defined. The optimal approach to therapy may eventually involve the use of medical therapy, including beta-blockade to stabilize patients, with delayed semielective coronary angiography and surgery in those who respond. Emergency angiography and surgery might then be reserved for the high-risk group of patients whose pain persists during optimal medical therapy.

Painless ST-segment depression in patients with angina pectoris. Correlation with daily activities and cigarette smoking

Ambulatory electrocardiographic monitoring was employed in 33 patients with angina pectoris and abnormal stress tests to determine the frequency with which myocardial ischemia manifested by painless ST-segment depression occurred during normal activity. ST-segment depression occurred in 24 patients during the monitoring period; and in 21, it occurred either solely in the absence of pain or both with and without pain. Of 109 recorded episodes of ST-segment depression, 61 percent were painless. The frequency of painless ST-segment depression was independent of activity other than automobile driving, during which all episodes were painless. In patients who smoked cigarettes, ST-segment depression was more common while smoking, but the incidence of painless ST-segment depression was not altered. The study indicates that ST-segment depression occurs more commonly in the absence than in the presence of chest pain and that ambulatory electrocardiographic monitoring is a useful method of determining the frequency of myocardial ischemia during normal daily activity.

Treatment of spontaneous angina pectoris with beta blocking agents. A clinical, electrocardiographic, and haemodynamic appraisal

Propranolol and practolol were tested in patients with repeated daily occurrence of spontaneous angina. Twenty-one showed ST segment depression (type I) and 15 ST segment elevation (type II) during angina. The efficacy of the treatment was evaluated in subjective (number of reported episodes of pain) and objective terms (number of episodes of electrocardiographic abnormalities documented during periods of continuous recording): practolol was fully effective in 42 per cent and propranolol in 38 per cent of type I cases; in type II angina 73 per cent of the cases fully responded to propranolol, none of the patients in this group given practolol improved. The study also showed that: (a) the effects on angina are strictly dose-dependent, and optimal results are achieved at individualized doses; (b) within the same subject the response may be preferential to one beta-blocker as opposed to the other; (c) propranolol is more effective in type II angina; (d) the occurrence of heart failure is uncommon even with high doses of beta blockers;(e) the relief of angina is due to prevention of ischaemia and not to a placebo or anaesthetic effect; (f) the prevention of ischaemia is not adequately explained by reduction of the mechanical effort and the oxygen need of the myocardium; (g) the antianginal effect is possibly dissociated from the beta blockade of the heart. The hypothesis that beta-blocking agents influence the conronary vasomotion is discussed.

Anginal pain referred to the teeth. Report of a case

A case is reported in which initial anginal pain was localized to the area of the left posterior teeth. Subsequently the patient reported that at certain times he experienced pain in the area of the left posterior teeth with concomitant chest pain while at other times the pain was confined to the teeth.

Left and right heart haemodynamics during spontaneous angina pectoris. Comparison between angina with ST segment depression and angina with ST segment elevation

The function of both right and left sides of the heart was studied during spontaneous attacks of angina pectoris at rest in 7 patients showing ST depression (type I) and 4 showing ST elevation (type II) during the attack. In none of the 44 type I attacks and 29 type II attacks which were recorded did circulatory changes; the latter were different in the two groups. Type I attacks showed: a) a brief fall in arterial pressure, accompanied by b) a rise of right atrial and pulmonary wedge pressures and c) a decrease of cardiac output, right and left stroke work, the mean rate of systolic ejection, and indirect left ventricular pre-ejection dP/dt. In the course of the attack a hypertensive phase followed, which was paralleled by an increase of heart rate, cardiac output, left and right stroke work, and mean systolic ejection rate, left dP/dt; right atrial pressure and wedge pressure remained raised. All of the circulatory functions started to revert towards the pre-attack levels coincident with the waning phase of the electrocardiographic alteration, the latter occurring either spontaneously or after nitroglycerin. Type II attacks for the entire duration of the electrocardiographic changes showed: a) a reduction of arterial pressure, cardiac output, right and left stroke work, mean systolic ejection rate, and left dP/dt, b) a rise of right atrial and wedge pressures, and c) quite small changes of heart rate. When the electrocardiogram started to revert to the pre-attack aspect, the cardiac function rapidly improved and, after a supernormal phase, returned to the basal levels in about 2 minutes. It is concluded: 1) that no circulatory factor interfering with the mechanical effort of the heart is responsible for eliciting spontaneous angina: 2) that in type I attacks right and left ventricular impairment occurs which recovers rapidly, possibly through a sympathetic compensation; 3) that in type II attachs dysfunction of both sides of the heart occurs and persists throughout the episode of electrocardiographic alteration; 4) that the dynamic impairment is probably more severe in type I than in type II angina.

Left ventricular pressure responses in post-angiographic angina

Alterations in left ventricular end-diastolic pressure and in dp/dt observed in ten patients with coronary heart disease who developed angina pectoris following left ventricular cineangiography were compared with those of six other patients who developed angina spontaneously and with patients who underwent left ventricular cineangiography without experiencing angina. In the patients with post-angiographic angina there was a greater increase in end-diastolic pressure than that seen in the other patients, but there was no significant change in dp/dt. Changes in left ventricular pressure associated with post-angiographic angina would appear to reflect the combined effects of increased preload provided by the contrast material and of ventricular dysfunction including diminished compliance associated with angina. A rise in end-diastolic pressure greater than 20 mmHg following left ventricular cineangiography should alert the physician that the patient may be having myocardial ischemia.