Effect of partial agonist activity in beta blockers in severe angina pectoris: a double blind comparison of pindolol and atenolol

The use of beta adrenoceptor blockade in the treatment of rest angina is controversial, and the effects on severe angina of partial agonist activity in beta blockers are unknown. Eight patients with effort angina and seven with effort and nocturnal angina and severe coronary artery disease were studied initially when they were not taking any antianginal drugs. Pindolol 5 mg thrice daily (with partial agonist activity) and atenolol 100 mg daily (without partial agonist activity) were given for five days each in a double blind randomised manner. Diaries of angina were kept and treadmill exercise testing and ambulatory ST monitoring performed during the last 48 hours of each period of treatment. Daytime and nocturnal resting heart rates and the frequency of angina were significantly reduced by atenolol compared with pindolol (p less than 0.01). The duration of exercise was significantly increased and the frequency, duration, and magnitude of daytime and nocturnal episodes of ST segment depression on ambulatory monitoring were reduced by atenolol. Reduction in resting heart rate is important in the treatment of both effort and nocturnal angina. Partial agonist activity in beta adrenoceptor antagonists may be deleterious in patients with severe angina pectoris.

Diagnosis of broad complex tachycardias with ambulatory monitoring of atrial electrography

Simultaneous 24 hour ambulatory monitoring of the surface electrocardiogram and the intra-atrial electrocardiogram was evaluated in eight patients with broad complex tachycardia. The technique using a J shaped atrial pacing wire permitted a distinction between ventricular tachycardia and supraventricular tachycardia in all eight patients. Formal electrophysiological testing would still be required, however, in patients in whom diagnostic doubt remained.

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.

Inability of the ST segment/heart rate slope to predict accurately the severity of coronary artery disease

Analysis of the ST segment/heart rate slope during exercise testing has been suggested as a method of accurately predicting the presence and severity of coronary artery disease. Exercise tests were performed in 78 patients presenting with the chest pain to determine the maximum ST segment/heart rate slope. In 21 (27%) patients the ST segment/heart rate slope could not be calculated in any electrocardiographic lead. In the remaining 57 (73%) patients the maximum ST segment/heart rate slope accurately predicted the presence or absence of coronary disease in 44 patients (sensitivity 90%, specificity 40%). In addition, the extent of coronary disease was accurately predicted in 24 patients (sensitivity 42%). Thus the maximum ST segment/heart rate slope did not perfectly predict either the presence or the severity of significant coronary artery disease.

Safety and effectiveness of a portable external automatic defibrillator-pacemaker

Sudden cardiac death in the community can be reduced by early resuscitation. The commonest arrhythmia encountered in this setting is ventricular fibrillation. A portable external automatic defibrillator-pacing machine for use by emergency services and laymen after basic training, has recently been introduced. This device has a tongue-abdominal pathway for sensing the electrocardiogram and respiration, as well as delivery of current. In its automatic mode, the machine cannot defibrillate unless the patient's breathing and gag reflex are virtually absent. The decision-making characteristics of the machine were defined in isolation from the patient using simulated ECG signals and recordings of arrhythmias obtained during cardiac surgery and during electrophysiological studies. The pathway was evaluated separately by attaching it to a conventional defibrillator and using it in the elective cardioversion of 15 patients. Electrode sites were examined and creatine phosphokinase (CPK) and creatinine phosphokinase isoenzyme (CPKMB) release determined following conversion. Repeated playback of the same 34 minutes of selected recordings showed that decisions were consistent 95% of the time. Automatic pacing always occurred with asystole. ECG signals less than 0.35 mV in amplitude were not recognized, but a manual override switch could be operated in those circumstances where there was failure to act upon fine ventricular fibrillation. Defibrillation of 50% of the recordings of supraventricular and ventricular tachycardia did occur, but this could not have happened in practice unless the patient was unconscious, and in addition, the operator failed to countermand this decision. The tongue-abdominal pathway yielded good recordings of the ECG.(ABSTRACT TRUNCATED AT 250 WORDS)

Variable susceptibility to dynamic coronary obstruction: an elusive link between coronary atherosclerosis and angina pectoris

Growing evidence suggests that dynamic coronary obstructions play an important but elusive role in the genesis of ischemic events. Dynamic coronary obstructions can develop during certain phases of coronary disease as a result of a variable combination of vasoconstriction, arterial wall lesions, and increased thrombotic tendency. In a certain phase of their disease some patients develop dynamic coronary obstruction, while others with a similar degree of fixed atherosclerotic obstruction do not.

Precordial electrocardiographic mapping in the identification of patients with left main stem narrowing

This study was designed to determine if exercise testing using 16-lead precordial mapping can be used to identify patients with left main stem narrowing. In a group of 235 consecutive patients undergoing coronary angiography there were 35 patients with left main stem narrowing. The patients with left main stem disease differed from the others in that not only did they develop extensive S-T segment depression, but more specifically these changes occupied a characteristic position high on the precordium above the usual site of the precordial leads of the 12-lead electrocardiogram. This finding was then tested prospectively in a second group of 100 patients. Fourteen of the 100 patients had left main stem narrowing; the sensitivity and specificity of S- T segment changes high on the precordium in identifying patients with left main stem disease were 82 and 84% respectively. Thus precordial mapping and exercise testing is valuable in the diagnosis of patients with left main stem narrowing. The technique is simple and inexpensive and provides data not available using the conventional precordial leads of the 12-lead electrocardiogram.

Factors influencing R wave amplitude in patients with ischaemic heart disease

R wave amplitude changes during exercise have been ascribed to alteration in left ventricular volume and their measurement advocated for the improved diagnosis of coronary disease. The reproducibility of exercise QRS changes and their relation to ST segment depression, respiratory pattern, and left ventricular volume during ischaemia were studied in 10 patients with angina and coronary disease. QRS amplitude was measured in a 16 lead precordial map during three identical exercise tests in each patient and left ventricular volume assessed continuously using gated blood pool imaging with a single scintillation probe during manoeuvres to provoke ischaemia. During exercise, QRS amplitude increased or remained unchanged in four patients and fell in six patients in a consistent manner for each patient. R wave amplitude was not affected by changes in respiratory pattern. R wave amplitude did not alter in 33 of 39 episodes of left ventricular volume increase (mean 32%) or decrease (mean 36%) in end-diastolic counts. These findings suggest that precordial R wave changes during ischaemia are not determined primarily by alteration in left ventricular volume or the respiratory pattern. Though reproducible in each patient and following a definite relation to ST segment depression, the variable directional response during exercise suggest that R wave amplitude changes have little diagnostic value.

Significance of exercise induced ST segment elevation in patients with previous myocardial infarction

In order to determine the significance of exercise induced ST segment elevation in patients with previous myocardial infarction, we have studied 156 patients, 26 months (mean) after myocardial infarction. Each patient underwent 16 lead precordial electrocardiographic mapping before, during, and after exercise and in addition coronary arteriography was performed. There was no significant difference in the extent of coronary disease or abnormalities of left ventricular function between patients with exercise induced ST segment elevation that was noted to occur in leads with Q waves and those with ST segment elevation plus depression or those with ST segment depression alone. Patients without exercise induced ST segment changes had fewer coronary arteries involved than those who developed ST segment changes. Nineteen patients with exercise induced ST segment elevation alone underwent coronary artery bypass surgery; in 11 this resulted in complete abolition of the exercise induced ST segment elevation and was associated with symptomatic relief and patent grafts without alteration of left ventricular function. Thus, exercise induced ST segment elevation in patients with previous myocardial infarction should be considered as important as ST segment depression in terms of underlying myocardial ischaemia, coronary anatomy, and left ventricular function.

Projection of ST segment changes on to the front of the chest. Practical implications for exercise testing and ambulatory monitoring

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Effects of platelet inhibition on myocardial ischaemia

Ticlopidine, a potent inhibitor of platelet aggregation, was found to have no direct effects on coronary resistance or coronary flow in 5 dogs. To determine whether platelets can be implicated in the pathogenesis of myocardial ischaemia the effects of this drug were studied in 10 patients with proven coronary-artery disease and daily angina pectoris. Each underwent three single-blind treatments: (a) placebo for 2 weeks; (b) ticlopidine 500 mg for 4 weeks; and (c) placebo for 2 weeks. For 4 days after the end of each treatment ambulatory S-T segments were monitored and a record was kept of the reported frequency of chest pain. 4 weeks' treatment with ticlopidine resulted in a significant fall in both the reported frequency of chest pain and the number of episodes of S-T segment depression. This effect was most striking in those episodes of S-T segment depression that occurred without increase in heart rate and in the middle of the night. Thus, although the exact mechanisms remain to be clarified this study suggests that platelets may play an important part in the pathogenesis of myocardial ischaemia.

Facial swelling: a complication of transvenous pacing

A case of progressive venous thrombosis involving the superior vena cava is reported following implantation of a permanent transvenous pacemaker. Acute symptoms in the arm appeared after 18 months, but the symptoms of superior vena caval obstruction developed gradually, three years after pacemaker insertion. The diagnosis was confirmed by cavography and symptoms resolved with heparin therapy. Long-term anticoagulation is indicated when thrombosis is responsible for this uncommon but important complication of transvenous pacing.

Measurement of serum C-reactive protein concentration in myocardial ischaemia and infarction

Serum C-reactive protein (CRP) and creatine kinase (CK) MB levels were measured prospectively in patients with definite myocardial infarction, patients with spontaneous or exercise-induced angina, subjects undergoing coronary arteriography, and patients with non-cardiac chest pain. All individuals with infarction developed raised CRP levels and there was a significant correlation between the peak CRP and CK MB values. The CRP, however, peaked around 50 hours after the onset of pain at a time when the CK MB, which peaked after about 15 hours, had already returned to normal. In 20 patients who recovered uneventfully, CRP levels fell, returning to normal about seven days after infarction in four cases who were followed to this point. In eight complicated cases, including four who died within the first 10 days, the CRP level remained high. Angina alone or coronary arteriography did not cause a rise in the CRP or CK MB concentrations. Increased CRP production is a non-specific response to tissue injury and raised CRP levels in cases of chest pain with a normal CK MB indicated a pathological process other than myocardial infarction. Regular monitoring of CRP levels may also assist in early recognition of intercurrent complications occurring after myocardial infarction.

The use of propranolol and nifedipine in the medical management of angina pectoris

This study investigates the use of propranolol and nifedipine in the treatment of angina pectoris. The clinical response and the effects on the precordial 16-lead electrocardiogram before and after exercise were studied in 52 patients with frequent angina pectoris. Relief of chest pain and abolition of exercise-induced ST-segment depression was achieved in 16 patients on treatment with propranolol alone (mean dose, 300 mg/d). Of the remaining 36 patients, the precordial area and severity of exercise-induced ST-segment depression were unchanged in 8 patients, of whom 2 reported they were free from chest pain, improved in 10 patients of whom 4 reported they were free of chest pain, and abolished in 14 patients, all of whom were free from chest pain following treatment with both propranolol and nifedipine (mean dose, 50 mg/d). Four patients were unable to tolerate this combination. This study has shown that in patients who do not respond to treatment with propranolol alone the combination of propranolol and nifedipine can be used to control not only anginal pain, but also the precordial electrocardiographic manifestations of ischemia.

Myocardial ischemia and angina pectoris: the clinical problem in patients

The morbidity and mortality suffered by patients with coronary artery disease is probably caused by the development of myocardial ischemia. Angina pectoris occurs not only during stress but also at rest and at night. This suggests that myocardial ischemia may be caused by a variety of mechanisms. Ambulatory monitoring of ST segment changes was performed in 60 patients presenting with angina, positive ECG stress tests and coronary artery disease. 85% of ischemic ECG events were asymptomatic, 37% occurred with no increase in heart rate and 15% of episodes either lasted 20 minutes or more or fluctuated in severity. A controlled pilot study in ten patients showed that the combination of high dose propranolol and nifedipine produced a significant decrease in chest pain and episodes of ST depression. Radionuclide studies in 50 patients with angina and coronary artery disease have shown that stress (i.e., atrial pacing) produced different patterns of disturbed regional myocardial perfusion related to the patient's exercise capacity and eventually leading to a decrease in regional myocardial perfusion during the ischemic episode. St segment depression appeared only after the decrease in regional myocardial perfusion. These findings combined with past research suggest that patients with angina and coronary artery disease can suffer frequent asymptomatic disturbances of the regional myocardial perfusion. The frequency of these episodes and the time course for the recovery of the metabolic consequences mean that segments of ventricular myocardium may be constantly abnormal. The relative importance of changes in coronary tone and malfunction of platelets in the diseased coronary tree needs to be examined in clinical research. Pilot studies of antiplatelet agents have shown a significant beneficial effect on episodes of ischemia occurring at night and those occurring without any increase in heart rate. The techniques and observations in these patients with coronary artery disease all suggest that acute transient regional myocardial ischemia is caused by a variety of mechanisms. Further research using objective methods is required to discover the causes of ischemia and to rationalize treatment. f

The dose-response effects of nifedipine of ST-segment changes in exercise testing: preliminary studies

This study examines the effects of increasing doses of nifedipine on exercise-induced ST-segment depression in patients with severe typical stable angina pectoris. 10 patients underwent four 1-week treatment periods in a single-blind clinical trial. These were nifedipine 0, 30, 60, and 90 mg in divided doses daily. At the end of each week a maximum exercise test was performed using 16 precordial electrocardiographic leads and the ST-segment changes measured immediately after exercise. In 4 patients nifedipine produced no effects on these electrocardiographic parameters; 4 patients improved and 2 deteriorated. Thus, a dose of nifedipine, effective in 1 patient, can have opposite effects in another.

Treatment of angina pectoris with propranolol: the harmful effects of cigarette smoking

The effects of smoking on the treatment of angina has been studied in 10 patients. Each patient underwent 4 randomized 1-week treatments consisting of on and off smoking, and on and off propranolol (360 mg/day). At the end of each treatment a maximal exercise test was performed using 16 praecordial leads. Smoking was associated with a significantly higher heart rate, blood pressure, area and severity of ST-segment depression. This was not abolished by propranolol. Thus, smoking aggravates the simple haemodynamic variables used to assess myocardial oxygen requirements and the electrocardiographic signs of ischaemia; this is true even after treatment with propranolol.

Hypoplastic and fibrotic sinus node associated with intractable tachycardia in a neonate

A case of fetal and neonatal persistent atrial tachycardia is described in a child with complete transposition of the great arteries. At autopsy, serial sections of the conducting tissue showed that the sinus node was hypoplastic and markedly fibrotic. The sinus node consisted of a small area of cells clustered around the nodal artery. Although the underlying mechanism of neonatal persistent tachycardia is unclear, it is possible that the hypoplasia and fibrosis of the sinus node was the substrate in the present case. This mechanism should be considered in any newborn infant in whom sinus rhythm cannot be established.

Electrophysiological manifestations of non-penetrating cardiac trauma

Electrophysiological disturbances were observed in four cases of non-penetrating cardiac trauma. Ventricular tachycardia occurred both as an early and late complication in three, responding to medical treatment in two; it was cured by cryoablation in the other case. The fourth patient developed an isolated conduction defect associated with anteroseptal myocardial infarction, the coronary arteries and left ventricular function being normal.

The effects of propranolol on myocardial perfusion and metabolism during acute regional ischaemia

The unique physical properties of the short-lived inert and freely diffusing isotope 81mkrypton allow a continuous observation to be made of regional myocardial perfusion. Eighteen dogs were anaesthetised and a reversible snare placed on the left anterior descending coronary artery (LAD). 81mKrypton was used to study regional myocardial perfusion, and myocardial metabolism was assessed using the epicardial ECG and release of creatine kinase activity (CK). Six dogs did not undergo LAD occlusion ("sham operated"); in six other dogs the LAD was occluded (controls), and another six dogs were given propranolol, 0.5 mg/kg, 20 min after LAD occlusion. All the parameters were measured before and for 5 h after LAD occlusion. When compared to controls, dogs treated with propranolol showed significant improvement (p less than 0.01) in regional myocardial perfusion; smaller loss of electrically active myocardium for any given degree of early ST-segment elevation; and a delay in the release of CK activity from a local coronary vein. These results suggest that propranolol exerts a beneficial effect following the development of acute myocardial infarction.

Relation between the precordial projection of S-T segment changes after exercise and coronary angiographic findings

The recent introduction of electrocardiographic mapping permits measurement of the precordial area and severity of exercise-induced S-T segment changes. This study was designed to compare this technique with a modified 12 lead electrocardiogram in defining the degree and site of coronary artery disease. One hundred patients, who later had diagnostic coronary arteriography, underwent an exercise test using both 16 point precordial mapping and a modified 12 lead electrocardiogram. The sensitivity of electrocardiographic mapping (96 percent) for the diagnosis of coronary artery disease was significantly greater than that of the modified 12 lead electrocardiogram (80 percent). However, the specificity of the two lead systems was similar. Typical precordial projections of S-T segment change were found when the left main stem or proximal left anterior descending coronary artery were narrowed or when there was isolated disease of the left anterior descending or right coronary artery. Widespread precordial changes were found in patients with three vessel disease. Although there was no significant difference in the sensitivity (66 percent) and specificity (100 percent) of electrocardiographic mapping and of the 12 lead system in identifying three vessel disease, there was a significant difference in sensitivity (electrocardiographic mapping 74 percent, 12 lead system 42 percent) in identifying isolated single vessel disease. In addition, information regarding the presence of left main stem or proximal left anterior descending coronary arterial narrowing was obtained only with electrocardiographic mapping. The superiority of electrocardiographic mapping over the modified 12 lead electrocardiogram has been shown, and clinical application of this technique should be useful in the management of patients presenting with chest pain.

Projection of electrocardiographic signs in praecordial maps after exercise in patients with ischaemic heart disease

Praecordial surface maps of the electrocardiogram were recorded before and after exercise using 16 electrodes covering the left hemithorax. The ST segment and R and S wave changes were measured in the praecordial maps from 20 individuals with no detectable cardiovascular disease. These showed no significant alteration in ST segments of R/S. In contrast in 40 patients with angiocardiographically proven coronary artery disease it was possible clearly to outline the distribution, severity, and time course of praecordial areas of ST segment depression (36 patients) and ST segment elevation (10 patients). In addition these praecordial areas of ST segment changes were accompanied by a regional and significant fall in the R/S. The praecordial electrocardiogram with exercise complements the anatomical information obtained from the coronary arteriogram by clearly outlining electrocardiographic projections of regional myocardial ischaemia or cell death.

An experimental model for angina pectoris using krypton-81m. The dynamic balance between myocardial perfusion and metabolism

16 anesthetized and open chest dogs were studied. Regional myocardial perfusion was assessed using a constant infusion of krypton-81m (half-life 13 sec) into the aortic sinuses and a gamma camera linked to a digital computer. The epicardial electrocardiogram was recorded and the plasma activity of creatine kinase was measured in serial blood samples from the aorta and a local coronary vein draining the area of myocardium supplied by the left anterior descending coronary artery (LAD). These parameters were observed throughout the whole period of a 5-h experiment. Two reversible snares were positioned on the middle portion of this artery. A critical narrowing of this vessel was produced and a peripheral venous infusion of isoproterenol (causing a 5--10% increase in heart rate and a 10--15% fall in blood pressure) was used to increase myocardial oxygen demand. During infusion there was both a relative and absolute fall in regional myocardial perfusion together with evidence of myocardial ischemia in the epicardial electrocardiogram. Provided the infusion was discontinued within 30 min (8 dogs) myocardial perfusion and the epicardial electrocardiogram returned to normal during a 5-h recovery period. In addition there was no efflux of creatine kinase activity from the ischemic area. When infusion was continued for 1 h (4 dogs) permanent alterations in myocardial perfusion and the epicardial electrocardiogram occurred and there was increased creatine kinase activity released from the area of myocardium by the narrowed vessel. Infusion for 40 min in 4 dogs produced permanent alterations in the parameters measured in 2 and complete recovery in the remaining 2. A further 4 dogs were studied in the same way but without a snare on the coronary artery. Isoproterenol given for 1 h produced no effects on any of the parameters either during or after infusion.

Precordial mapping of ST-segment elevation and Q waves following anterior myocardial infarction. The effects of established beta-blocking drugs

The electrocardiographic (ECG) signs of ST-segment elevation and the development of Q was using 72-lead precordial surface mapping, and the release of creatine kinase (CK) activity has been studied in 47 patients with uncomplicated anterior myocardial infarction. These findings were compared with a further nine patients who had acute myocardial infarction but were receiving long-term beta-blocking drugs. It was found that ST-segment elevation and Q waves had rapidly changing and different natural histories and that beta-blocking drugs altered the natural history of ST-segment changes but had no effect on the pattern and time course for the loss of electrically active myocardium. There was a close relationship between the precordial area of ST-segment elevation at 2--3 h and the final development of Q waves in the patients with uncomplicated anterior myocardial infarction. No similar relationship could be found in those on beta-blocking drugs. The pattern of changes in plasma CK and its MB isoenzymes activity were similar for both groups. The relationship between early ST-segment elevation and the final area of Q waves may prove useful in clinical practice. This may not apply where beta-blocking drugs are commenced before the initial recording of ST-segment elevation.

Indication and clinical significance of exercise surface mapping

A technique of recording electrocardiographic maps after exercise is described. This technique allows a measurement to be made of the area of ST segment changes that are projected onto the front of the chest after exercise. A comparison of the sensitivity and specificity of this technique with the orthogonal lead system and a single chest lead showed that praecordial exercise mapping was significantly superior to the other two lead systems in the diagnosis of ischaemic heart disease and may help in identifying patients with extensive disease. In addition information obtained from praecordial exercise mapping can be used to increase the data that are obtained from Holter monitoring of ST segments. The place of the technique in the management of medical and surgical treatment remains to be evaluated.

The effect of established beta-adrenoreceptor-blocking therapy on the release of cytosolic and lysosomal enzymes after acute myocardial infarction in man

1. Serial venous blood samples were obtained from 45 patients with acute myocardial infarction. Ten of these patients were receiving beta-adreno-receptor-blocking drugs at the time of onset of chest pain and continued on these drugs during their stay in the coronary care unit. The activities of creatine kinase and its MB-isoenzyme (CK-MB) were assayed in the plasma. A lysosomal enzyme, beta-N-acetylglucosaminidase, was also assayed. 2. In the 35 untreated patients it was found that creatine kinase activity was maximal at a mean time of 21.3 +/- 1.3 h after the onset of chest pain, whereas in the patients receiving beta-adrenoreceptor-blocking drugs peak activity of the enzyme occurred at 24.4 +/- 0.7 h. 3. Peak CK-MB acitivity was also delayed from 18.1 +/- 1.6 h in the control group to 22.4 +/- 1.2 h in the treated patients. 4. The lysosomal enzyme showed a similar pattern of changes to that of CK-MB. Maximum activity in plasma occurred at 18.0 +/- 1.0 h after the onset of chest pain in the control group of patients. In the treated patients peak lysosomal enzyme activity was not found until 24.2 +/- 1.2 h. 5. These alterations in the time-course of plasma enzyme changes after acute myocardial infarction are consistent with the suggestion that beta-receptor antagonists may delay tissue damage during myocardial ischaemia.

A method for praecordial surface mapping of the exercise electrocardiogram

A technique for praecordial surface mapping of the exercise electrocardiogram is described. This showed the area, time course, and severity of ST segment depression as projected onto the front of the chest after exercise. Twenty normal volunteers and 20 patients with coronary artery disease have been studied. No changes were seen after exercise in the normal subjects but areas of ST segment depression appeared in all 20 patients with angina pectoris. In 5 of the 20 patients with coronary artery disease, the exercise test was repeated on a later date. There were no significant differences in the area of severity of electrocardiographic abnormalities recorded during the two tests. This technique may prove to be useful for diagnosis and assessing medical and surgical treatments in patients with ischaemic heart disease.

Electrocardiographic precordial mapping in anterior myocardial infarction. The critical period for interventions as exemplified by methylprednisolone

Serial 72-point precordial mapping of ECG has been recorded to describe the natural history of changes in the precordial areas of ST segment elevation and the development of Q waves in 51 patients with acute uncomplicated anterior myocardial infarction. Eight patients have been studied in the same way but received 25 mg/kg of methylprednisolone sodium succinate as a single intravenous injection within 6 hours from the onset of chest pain. There was a linear relationship between the stable precordial area of Q waves at 24 hours and the rapidly changing precordial areas of ST segment elevation at 2--3 hours, 5--6 hours and 12 hours after the onset of pain in the untreated patients. When methylprednisolone was given, the treated patients developed a smaller precordial area of Q waves at 24 hours than was predicted from the precordial area of ST elevation recorded before the drug was given. This study has introduced a technique that can provide a qualitative assessment of the relationship between ECG evidence of ischemia and infarction in each patient.

Effects of nifedipine on creatine kinase release during myocardial ischemia in dogs

25 anesthetized mongrel dogs underwent a left thoracotomy. Creatine kinase (CK) activity was measured in serial blood samples drawn simultaneously from the aorta and a coronary vein. The distribution of myocardial perfusion was determined by a continuous infusion of krypton-81m (half-life 13 sec) into the aortic sinuses. Heart rate and arterial blood pressure were also measured throughout the procedure. In 20 dogs regional myocardial ischemia was produced by ligation of a major branch of the left anterior descending coronary artery. Five of these dogs received 1 microgram.kg-1 nifedipine i.v. and a further 5 received 13 microgram.kg-1. Thoracotomy alone produced a slight rise in plasma CK activity but the arteriovenous difference (AV) across the segment of the heart remained positive over 5 h. Myocardial ischemia in the untreated dogs caused a considerable increase in CK activity and the AV difference became negative at 90 min. Treatment with the lower dose of nifedipine considerably reduced the plasma CK activity and the AV difference did not become negative until 3 h. Regional myocardial perfusion showed a significant improvement. Conversely, the higher dose of nifedipine produced a marked increase in the area of ischemia and an acceleration of CK release from the heart. This was associated with a decrease in arterial pressure and an increase in heart rate. These results show that nifedipine can be beneficial in experimental myocardial infarction but care must be taken to avoid hypotension and increases in heart rate.

The relationship between posture, blood pressure and electrophysiological properties in patients with paroxysmal supraventricular tachycardia

In 9 patients with paroxysmal supraventricular tachycardia the effects of tilting the body on the blood pressure and on responses during tachycardia or pacing revealed important effects that could influence the clinical presentation and the treatment required. Assessment of these reflex responses adds a major dimension to the understanding of the patient with supraventricular tachycardia.

The relationship between myocardial ischaemia and cell death during acute myocardial infarction

Praecordial mapping of the electrocardiogram (ECG) demonstrated the natural history of ST segment elevation, loss of R and appearance of Q waves in 50 patients suffering uncomplicated anterior myocardial infarction. The results showed that ST segment elevation has a complicated natural history. The loss of R wave electromotive force and development of Q waves were complete by 12 h following the onset of chest pain. This evidence for the loss of viable myocardium was complete before the MB-isoenzyme of creatine kinase (MBCK) was detected in the plasma. Regression analysis of these results showed a direct relationship between the praecordial area of ST segment elevation at 2 h (myocardial ischaemia) and the praecordial area of Q waves at 24 h after the onset of symptoms (cell death). The efficacy of interventions on the natural history of myocardial infarction might be assessed by their effects on the relationship between myocardial ischaemia and cell death.

Plasma lysosomal enzyme activity in acute myocardial infarction

N-acetyl-beta-glucosaminidase (EC 3.2.1.30, recommended name beta-N-Acetylglucosaminidase) was found to be a constituent of human cardiac lysosomes. beta-glucuronidase was also found in this tissue, while lysozyme, an enzyme present in leucocyte lysosomes, was not detectable in the heart. The activities of both N-acetyl-beta-glucosaminidase and beta-glucuronidase were elevated in plasma during the first 24 h after the onset of chest pain in patients with acute myocardial infarction and the peak levels of N-acetyl-beta-glucosaminidase correlated well with those of creatine kinase. N-acetyl-beta-glucosaminidase showed a further rise in plasma activity which gave a peak at 72 h after the onset of chest pain and this was accompanied by a rise in lysozyme activity. It is suggested that lysosome disruption caused by myocardial cell necrosis was responsible for the initial rise in plasma lysosomal enzyme activity and that the subsequent inflammatory reaction gave rise to the second peak.

The combined clinical and hemodynamic effects of trinitrin and propranolol

The clinical and hemodynamic effects of trinitrin (nitroglycerin) have been studied in 5 patients with long-established coronary artery disease who had been receiving long-term beta blockade therapy (propranolol). 5 similar patients not on propranolol acted as controls. Patients on propranolol reported as effective relief of angina with trinitrin as patients not on this therapy. Although the patients on propranolol had an initially lower systolic blood pressure and mean ventricular rate, sublingual trinitrin caused in both groups a similar fall in aortic pressure, pulmonary wedge pressure, oxygen consumption and stroke volume, together with a similar rise in ventricular rate. It was concluded that trinitrin was as effective, both subjectively and objectively, in patients on propranolol as in those without beta blockade and promoted similar side effects.

Safe amounts of contrast medium for angiocardiography in neonates and infants

The results were analysed of 485 (biplane) cineangiocardiograms performed in 200 consecutive cardiac investigations on neonates (under 4 wk) and infants (4 wk to 1 yr). 10 deaths occurred during or within 24 h of cardiac catheterization, all in patients who were profoundly acidemic because of their hemodynamic disturbance. A total dose of Cardio-Conray at any one investigation of 4-5 ml/kg body weight was satisfactory and without undue risk. Single injections of 1.5-2.0 ml/kg body weight were safe whilst providing optimal diagnostic information. The interval between multiple injections did not appear to affect the risk to the patients.

Streptokinase in acute myocardial infarction: a controlled multicentre study in the United Kingdom

In a multicentre trial of streptokinase in acute myocardial infarction 302 patients received an intravenous infusion of 2 500 000 IU of streptokinase over 24 hours, while 293 patients served as controls. Neither group received anticoagulants unless indicated by thromboembolic complications. No significant difference in mortality was evident during inpatient treatment nor at six-week or six-month follow-up. The inpatient death rate was 12-6% in the streptokinase group and 13-7% among controls. There was no significant difference in the peak levels or pattern of enzyme increase. The incidence of cardiac failure and reinfarction was similar in the two groups, but major arrhythmias were less common in those on streptokinase (P less than 0-05). In the streptokinase group there were 36 minor and six more serious haemorrhagic complications. Gastrointestinal haemorrhage may have contributed to the death of one patient in each group. There were 18 thromboembolic complications in the streptokinase group and 38 among the controls. Pathological examination of the hearts of 25 patients who had taken streptokinase and 24 controls showed no striking differences between the groups, but haemorrhagic infarcts were found in three patients who had received streptokinase. An infusion of streptokinase within 24 hours of the onset of acute myocardial infarction does not significantly affect the mortality or course of the illness up to six months.

Primary ventricular fibrillation and resumption of work, sexual activity, and driving after first acute myocardial infarction

The resumption of work, sexual activity, and driving were studied in 32 patients who had suffered primary ventricular fibrillation after their first myocardial infarction. They were compared with 95 patients whose myocardial infarction was not so complicated. Though initially slowing rehabilitation, primary ventricular fibrillation did not affect ultimately either the return to work or the resumption of normal sexual activity and driving.

Prognostic significance of acute systolic hypertension after myocardial infarction

The clinical behaviour and mean peak serum aspartate aminotransferase (SGOT) values of 106 patients admitted to a coronary care unit with acute myocardial infarction who displayed acute systolic hypertension were studied. Another 106 normotensive patients with acute myocardial infarction acted as controls. Neither group had established hypertension. The mortality rate, incidence of cardiac failure, major arrhythmias, and mean peak SGOT were significantly greater in the hypertensive group, within which the duration of hypertension was correlated with mean peak SGOT levels--through there was no definite relation between the height of systolic or diastolic pressure and SGOT. Transient systolic hypertension after acute myocardial infarction was therefore associated with a relatively poor prognosis, but our observations suggest that patients with a systolic blood pressure of at least 170 mm Hg might benefit from early hypotensive treatment.

Low voltage electrocardiogram after acute myocardial infarction

In a retrospective study of patients with acute myocardial infarction admitted to a coronary monitoring unit in 1971 12 per cent (39 patients) had low voltage electrocardiograms within 72 hours of admission. Of these, 7 patients (18%) died while in hospital and a further 9 (23%) died within one year of their infarction. Of the 23 patients who survived, 16 were severely incapacitated by their symptoms at the one-year follow-up. A low voltage electrocardiogram in association with acute myocardial infarction appears to imply a poor prognosis in terms of both mortality and morbidity, independently of other prognostic indices.

Carcinoma of the oesophagus with "swallow syncope"

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