Aneurysm of the left anterior descending coronary artery after chest trauma

A 28-year old man developed transmural anterior wall myocardial infarction after a car accident despite the absence of external signs of chest trauma. Coronary angiography one month after the accident demonstrated an aneurysm of the left anterior descending artery. Angiography five and eleven months afterwards showed almost total regression of the aneurysm. The man remained asymptomatic with no signs of residual ischaemia one year after the accident. Blunt trauma to the chest is a well-known cause of cardiac damage including myocardial contusion, rupture of the ventricular wall, septum, papillary muscles or chordae tendineae. Myocardial infarction secondary to distinct injury to a coronary artery has only seldom been described. Visualization of a localized lesion in a coronary artery of an otherwise non-atherosclerotic coronary tree supports the traumatic origin of a myocardial infarction.

Changing electrocardiographic findings in pulmonary embolism in relation to vascular obstruction

Electrocardiographic (ECG) findings in 87 consecutive patients with from minor to massive pulmonary embolism are presented. ECG changes suggestive of acute right ventricular strain defined as the occurrence of complete (c) or incomplete (inc) right bundle branch block (RBBB), an SIQIIITIII pattern, inverted T waves in the second and third precordial leads and/or an increase in the frontal QRS axis of 20 degrees C or more were found in 71 patients (82%). The prevalence of c and inc RBBB and the increase in frontal QRS axis correlated with the extent of embolization (angiographic or scintigraphic score), while the appearance of the SIQIIITIII pattern did not. No patient with a vascular obstruction of two thirds or more had an ECG free of signs of right ventricular strain. In 9 of 11 embolectomized patients with c RBBB, c RBBB disappeared within 24 h postoperatively. Among patients with an embolization of 45% or more, those with c RBBB had a shorter symptom duration, fewer embolic episodes and a lower pulmonary artery pressure than those without c RBBB. As ECG abnormalities were transient and changing in nature, serial ECG recordings are recommended. Pronounced ECG signs of right ventricular strain should, as they may reflect both massive and short-lasting vascular obstruction, arouse the suspicion of pulmonary embolism suitable for embolectomy.

Emergency embolectomy in a patient with massive pulmonary embolism during second trimester pregnancy

Emergency pulmonary embolectomy was performed successfully on a patient in her second trimester of pregnancy. The patient had severe right ventricular failure due to obstruction of 85% of the pulmonary arterial circulation. Three months after embolectomy she was delivered of a normal infant. The problem of significant but misinterpreted or overlooked clinical and electrocardiographic signs of pulmonary embolism is discussed. Thrombolytic therapy during pregnancy imposes considerable risk of bleeding with deleterious effects on both mother and fetus. In our opinion, emergency embolectomy during extracorporeal circulation is the best treatment in case of massive emboli during pregnancy.

Altered global myocardial substrate preference at rest and during pacing in coronary artery disease with stable angina pectoris

In 21 control subjects with atypical chest pains and normal coronary arteries and in 64 patients with stable angina and coronary artery disease (CAD), myocardial exchanges of free fatty acids, glucose, lactate, citrate, glutamate, alanine and oxygen were determined before, during and after pacing. At rest, myocardial uptake of fatty acids was 50% lower in CAD patients than in the control subjects (p less than 0.001), whereas uptakes of glucose and lactate were twice as high (p less than 0.01). CAD patients showed increased myocardial glutamate uptake (p less than 0.001) and alanine release (p less than 0.001). In control subjects, myocardial fatty acid uptake was directly related (r = 0.54, p less than 0.01), whereas uptakes of glucose (r = -0.42, p less than 0.05) and lactate (r = -0.46, p less than 0.05) were inversely related to arterial fatty acid levels. Citrate release was inversely related to glucose uptake (R = 0.44, p less than 0.05). These relations were absent in CAD patients. Glutamate consumption correlated only with glucose uptake in CAD patients (p less than 0.001) but did so with lactate uptake and alanine release in all individuals (p less than 0.001). Pacing caused angina in the CAD patients but not in the control subjects. Pacing induced no metabolic changes among control subjects but provoked myocardial lactate release in 40 CAD patients, including an additional decrease of fatty acid uptake (p less than 0.05) and increase of glucose uptake (p less than 0.05) compared with resting levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary hyperparathyroidism of morbid obesity regresses during weight reduction

In order to test the relation between obesity and the secondary hyperparathyroidism found in markedly overweight subjects, 24 morbidly obese patients were studied before and after a weight loss of 35.9 kg obtained by a nutritionally adequate, intermittent very-low-calorie diet. Overweight was reduced from 98 +/- 34% to 44 +/- 19%. Serum total calcium did not change, but serum ionized calcium (Ca2+) increased from 1.22 +/- 0.04 mmol/L to 1.25 +/- 0.04 mmol/L (P less than .001). A corresponding fall was observed in serum parathyroid hormone (s-PTH), which decreased from 47.2 +/- 21.7 pmol/L to 35.2 +/- 19.4 pmol/L (P = .01). The change of s-PTH was positively associated with the reduction of body weight (r = .50, P less than .05) and with the reduction of overweight (r = .55, P less than .01). Regarding calcium binding substances, serum albumin remained low. The initially lowered serum phosphate and bicarbonate both rose (P less than .001). Plasma lactate and plasma free fatty acids (FFAs) decreased (P less than .001). The study supports our hypothesis that the change profile of calcium complexing anions in obesity interferes with the tubular reabsorption of calcium, which in turn lowers serum Ca2+, thus promoting hyperparathyroidism. Along with weight loss, concentrations of calcium complexing anions returns towards normal values and the secondary hyperparathyroidism regresses.

Aortic regurgitation after surgical relief of subvalvular membranous stenosis. A long-term follow-up study

A postoperative follow-up study of 21 cases of discrete membranous subvalvular aortic stenosis is presented. The age at operation was 6-47 (mean 16) years, and the follow-up time 0.6-16 (mean 6.7) years. Preoperatively most patients were in NYHA function class II or III and had high peak systolic pressure gradient, left ventricular hypertrophy and/or cardiothoracic index greater than 0.50. At follow-up all but six patients were in NYHA class I, the Doppler-estimated peak systolic gradient was 0-36 (mean 18) mmHg, the cardiothoracic index unchanged and the mean left ventricular hypertrophy score had declined from 4.3 to 2.3. Of 13 patients without aortic regurgitation preoperatively, eight had regurgitation at follow-up (group I) and five did not (group II). The interval to follow-up was significantly longer and the preoperative peak systolic gradient was greater in group I than in group II. Aortic regurgitation may develop even after surgical relief of discrete membranous subvalvular aortic stenosis, possibly associated with high preoperative pressure gradient and time from operation. Regular postoperative Doppler echocardiography is therefore recommended.

Hemodynamic and cardiac metabolic changes during nicardipine-induced myocardial ischemia

After 10 mg nicardipine IV a patient with stable angina developed chest pain and ST-segment depression accompanied by excessive tachycardia, low arterial blood pressure, and initially decreased coronary sinus blood flow. Measurements of arterial concentrations and cardiac exchanges of lactate, glucose, free fatty acids, glutamate, and alanine showed alterations indicative of severe ischemia.

Atrial natriuretic peptide during pacing in controls and patients with coronary arterial disease

At rest, during cardiac catheterization, aortic plasma levels of immunoreactive atrial natriuretic peptide did not differ between 10 controls with atypical chest pains and normal coronary arteries and 9 patients with stable angina pectoris and coronary arterial disease (55.2 +/- 19.8 vs. 64.8 +/- 19.8 pg/ml, NS). Nor did atrial natriuretic peptide values differ between the two groups during or after atrial pacing (150 beats/minute), which induced electrocardiographic and metabolic signs of acute myocardial ischaemia in the patients with coronary arterial disease but in none of the controls. Pacing, when carried out for more than 300 seconds, induced an increase of plasma atrial natriuretic peptide that correlated with duration of pacing (r = 0.80, P less than 0.001), and similarly in controls and patients with coronary arterial disease. In a second part of the study, which included 2 controls and 2 patients with coronary arterial disease, post-pacing coronary sinus concentrations of atrial natriuretic peptide were 10-20 times higher than peripheral levels (415- greater than 890 pg/ml). The concentration of atrial natriuretic peptide rose as blood from the caval veins (34 +/- 7 pg/ml) entered the right atrium (56 +/- 24 pg/ml), but thereafter was unchanged in the pulmonary artery (51 +/- 3 pg/ml) and the aorta (46 +/- 9 pg/ml). In conclusion, the results gave no evidence for ischaemic heart disease without congestive cardiac failure to be associated with altered levels of atrial natriuretic peptide. It was confirmed that atrial pacing stimulates the secretion of atrial natriuretic peptide which is produced by the heart and released via the coronary sinus into the circulation.

Whole blood versus plasma measurements of glutamate and alanine across the human myocardium

Comparison of whole blood and plasma aorto-coronary sinus concentration differences of glutamate and alanine were made before, during and after coronary sinus pacing in seven patients with normal and six patients with stenotic coronary arteries. Mean differences between duplicate analyses were greater in whole blood than plasma both of glutamate (7.5 +/- 5.8 vs. 3.3 +/- 3.0 mumol/l, p less than 0.001) and of alanine (7.9 +/- 7.0 vs. 3.8 +/- 3.4 mumol/l, p less than 0.001). Concentrations of glutamate were 3.4 and of alanine 1.4 times higher in whole blood than in plasma. Blood cells were calculated to be responsible for about 20% of glutamate and alanine blood exchanges across the heart. Plasma and whole blood fluxes were closely positively correlated (glutamate:r = 0.81, alanine:r = 0.88) and had always the same direction. Differences in myocardial exchanges of amino acids between the patients with and without coronary artery disease, as well as rapid changes during pacing, could be demonstrated in plasma analyses but were not significantly reflected in whole blood glutamate determinations. This seemed to be due to the greater variations in whole blood analysis. In conclusion, differences in aorto-coronary sinus plasma concentrations reflected, although underestimated, whole blood fluxes. Because of considerable gains in precision of analysis, plasma should be preferred to whole blood for evaluations of glutamate and alanine exchanges across the human heart.

Dose-related haemodynamic effects of nicardipine during rest and exercise and variable anti-anginal effects in patients with chronic stable angina

The effects of increasing doses of i.v. nicardipine (2.5, 5.0 and 7.5 or 10.0 mg) on blood pressure, heart rate and exercise performance were studied in 12 patients with chronic effort angina. Plasma nicardipine concentrations correlated closely with the infused doses (r = 0.90). Resting haemodynamic changes after nicardipine included a dose-related fall in systolic (5%, 13%, 15%) and diastolic (0%, 6%, 8%) blood pressure and a rise in heart rate (10%, 19%, 30%). Rate-pressure product was slightly increased after the highest dose (10%). During exercise, maximal systolic blood pressure decreased (3%, 9%, 9%) and heart rate increased (2%, 4%, 9%) but the rate-pressure product remained unchanged. Exercise tolerance improved in 10 patients as indicated by prolonged exercise duration in all, delayed appearance of ST-segment depression in 6, decreased maximal ST-segment depression in 5, and abolished (N = 3) or diminished (N = 4) anginal pain at the end of exercise after optimal nicardipine dose. Five of the 10 patients obtained maximum benefit after the highest dose. The other five patients improved after 2.5 or 5.0 mg but deteriorated (N = 4) or had no further benefit when the dose was increased (N = 1). One patient deteriorated even after the lowest dose, whereas one patient neither improved nor deteriorated after any dose. The patients who deteriorated after low or high doses tended to be more severely diseased than those who tolerated the maximal dose well. The results stress the importance of individual dose titration of nicardipine to ensure maximum benefit in patients with chronic effort angina.

Metabolic and hemodynamic effects of nicardipine during pacing-induced angina pectoris

During repeat exercise testing in 10 patients with stable angina, individual optimal doses of nicardipine were determined. Hemodynamic values and cardiac metabolism were studied during 2 pacing periods carried out before and after this dose (mean 5.3 mg). Postpacing ST-segment depression diminished (1 mm) after nicardipine administration (p less than 0.05), whereas pacing time to onset of angina did not change. Nicardipine administration increased heart rate 16% (p less than 0.005) and reduced systolic (10%) and diastolic (8%) blood pressures (both p less than 0.005). Coronary blood flow increased 16% (p less than 0.05) and coronary vascular resistance decreased 24% (p less than 0.01). Myocardial oxygen consumption was unchanged despite an 11% decrease in rate-pressure product during pacing (p less than 0.02). In the control state before nicardipine administration, metabolic signs of ischemia included release of lactate across the heart in 7 patients, decreased mean free fatty acid and glutamate uptake and alanine release during pacing, together with increased glucose uptake and citrate release during recovery. After nicardipine lactate release decreased in 5 of the 7 patients, pacing no longer changed free fatty acid, glutamate and alanine uptake/release from the level at rest. During recovery glucose uptake was reduced and citrate release was unaffected. The hemodynamic data indicate that nicardipine is a systemic and coronary vasodilator, increasing oxygen supply to the ischemic myocardium. The metabolic results indicate a change in substrate utilization toward that of normal heart, suggesting improved aerobic energy supply.

Altered plasma concentrations of glutamate, alanine and citrate in the early phase of acute myocardial infarction in man

Plasma levels of glutamate, alanine, free fatty acids (FFA), citrate, glucose, insulin, lactate, creatine kinase and aspartate aminotransferase were determined frequently during the first 2-48 h after onset of chest pain in 10 patients who developed acute myocardial infarction (AMI) and in 8 who did not (non-AMI). An initial decrease in plasma glutamate and increase in alanine was found in AMI compared to non-AMI patients. The AMI group showed early, moderate rises of plasma FFA and citrate concentrations, positively related to the initial ST-segment elevation and to the enzymatic estimated infarct size. The AMI patients were continuously hyperglycaemic, but their relative insulin response i.e. plasma glucose/insulin ratio was identical to that of non-AMI patients. Lactate values did not differ between the two groups. Via participation in the malate-aspartate shuttle and by shunting pyruvate to alanine instead of lactate, glutamate is of importance for maintaining myocardial glucose utilization. Our finding of initial low plasma glutamate concentrations after onset of myocardial infarction suggests insufficient glutamate supply to the ischaemic myocardium. On basis of this and animal experiments, an external supply of glutamate might be a 'metabolic' treatment of AMI, alternative or additional to glucose-insulin-potassium infusion in order to promote myocardial glucose oxidation.

Treatment of pulmonary embolism with full-dose heparin, streptokinase or embolectomy--results and indications

The results of treatment of pulmonary embolism with heparin (n = 34), streptokinase (n = 28) or embolectomy (n = 25) are presented. The treatment groups represented different degrees of embolization with acute embolic scores (possible maximum: 20, mean +/- SD): 5 +/- 4, 9 +/- 3 and 13 +/- 3, respectively (p less than 0.0001). The post-treatment embolic score (mean +/- SD) for patients with acute massive central emboli (score greater than or equal to 9) was: 6 +/- 4 (n = 7) and 3 +/- 2 (n = 15) in the streptokinase and embolectomy groups, respectively, (p less than 0.01). The hospital mortality was 6% (n = 2), 21% (n = 6) and 20% (n = 5) in the heparin, streptokinase and embolectomy groups, respectively (p less than 0.05). The 5-year cumulative survival (+/- SE) was 68% +/- 10, 64% +/- 10 and 80% +/- 8, respectively (p: NS). The relative survival (hospital and late deaths, observed/expected) stratified according to acute embolic score showed the best results in the embolectomy group. Systolic pulmonary artery pressure greater than 60 mmHg was found in cases with a duration of symptoms greater than 7 days and/or with greater than or equal to 25 anamnestic recurrent embolic episodes before diagnosis, indicative of a gradual increase in pulmonary artery pressure and of partly organized non-lyseable emboli. Embolectomy carried a low risk of complications (8% with cerebral reduction). Streptokinase treatment was associated with serious complications (18% with cerebral reduction/fatal hemorrhage). Pulmonary embolectomy should be recommended in all cases with emboli in the main branches of the pulmonary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Scintigraphy and angiography in pulmonary embolism

In 14 patients with acute pulmonary embolism, pulmonary artery angiography was made within 6 h after ventilation-perfusion scintigraphy. The extent of embolization was evaluated by an embolic score system with a maximum value of 20 in cases of complete bilateral occlusion. The perfusion scintigraphic and pulmonary angiographic embolic scores correlated (r = 0.47), but the paired values differed (p less than 0.05). Exclusion of four cases with non-complete obstructing emboli in the main branches of the pulmonary artery rendered the differences of the paired scores not significant, with mean scintigraphic and angiographic scores of 9.7 and 10.1, respectively (r = 0.79). The four cases with non-complete obstructing central emboli had mean scores with the scintigraphic and angiographic method of 9.0 and 16.2, respectively (p less than 0.01), implying that the scintigraphic method may underestimate the degree of embolization in cases with non-complete obstructing central emboli.

Increased parathyroid hormone as a consequence of changed complex binding of plasma calcium in morbid obesity

To evaluate whether changed plasma calcium binding might lead to a secondary increase of parathyroid hormone in morbid obesity, fasting measurements of serum ionized, ultrafiltrable and total calcium, calcium binding substances, and parathyroid hormone were undertaken in age- and sex-matched groups of obese (n = 44) and normal weight subjects (n = 52). The 24-hour urinary calcium excretion and clearance of creatine were also measured. Calcium binding to proteins was changed. Serum total proteins and protein-bound calcium did not differ, but serum albumin was decreased in obesity. Consequently, obese subjects did not reveal the normal dependency of protein-bound calcium upon albumin. Calcium binding to other substances was also changed. Serum phosphate and bicarbonate were decreased, while the concentrations of citrate, lactate, acetoacetate, 3-hydroxybutyrate, free fatty acids, and urate were all increased, leaving the total concentration of plasma complex-bound calcium unchanged. Nevertheless, these reciprocal changes increase the concentrations of less readily reabsorbable anions in the renal ultrafiltrate. The changed pattern of calcium binding in serum of the obese subjects may serve to explain our findings of increased urinary calcium excretion, lowering of serum ionized calcium and increased parathyroid hormone levels, changes being significantly correlated with degree of overweight.

Improved myocardial lactate extraction after propranolol in coronary artery disease: effected by peripheral glutamate and free fatty acid metabolism

Ten patients with chronic effort angina and coronary artery disease (luminal diameter reduction greater than 75%) were stressed by atrial pacing (140 beats/minutes) before and 15 minutes after intravenous propranolol (mean dose 7.4 mg). Myocardial substrate exchange of oxygen, blood lactate, plasma free fatty acids, citrate, glucose, glutamate, and alanine as well as coronary sinus blood flow were measured. Coronary sinus blood flow, oxygen consumption, and systemic haemodynamics did not change after propranolol. Propranolol did not influence arterial lactate concentration, and it reduced the arterial concentration of free fatty acid by 37% and increased that of glutamate by 21%. During pacing myocardial lactate extraction increased in all 10 patients; in two lactate release was converted to lactate uptake. Propranolol reduced free fatty acid uptake and increased glutamate uptake during pacing. For both substances the changes in aortocoronary sinus differences or in uptake or both correlated positively with the changes in their delivery to the heart from extracardial sources (arterial concentrations/loads). In the unstressed state before pacing, aortocoronary sinus lactate differences correlated inversely with free fatty acid differences and positively with those of glutamate. During pacing the relation between lactate and glutamate differences remained positive while the inverse correlation between lactate and free fatty acid differences was lost. Myocardial citrate release was halved during pacing and recovery. Propranolol did not influence alanine or glucose exchanges. An improved myocardial lactate extraction after propranolol administration may be secondary to decreased free fatty acid uptake or increased glutamate uptake or both. In the unstressed state both mechanisms may be of importance. During pacing induced ischaemia, increased glutamate uptake is more likely than reduced free fatty acid uptake to be the mechanism responsible for the improvement in myocardial lactate extraction. The propranolol mediated alterations in myocardial substrate exchanges may reflect the extracardial effects of the drug.

Reproducibility of coronary haemodynamics and cardiac metabolism during pacing-induced angina pectoris

The reproducibility of coronary sinus blood flow (CSBF) (thermodilution technique) and myocardial metabolism (exchange of oxygen, lactate, free fatty acids, glucose, citrate, glutamate and alanine) during two identical pacing periods separated by 45 min were studied in eight patients with chronic coronary artery disease. The mean of the individual difference (delta-values) between values during the first (T1) and second (T2) test, at corresponding times (rest, pacing and after 3-5 min of recovery), were calculated and expressed as a percentage of the resting level of each parameter in order to assess their reproducibility. All patients experienced angina pectoris during both pacing sessions, and pacetime to onset of symptoms did not differ between the tests. Group values for haemodynamics and exchange of metabolites were acceptably reproducible throughout the period under study. Mean delta-values of CSBF ranged from 10% to 16% and myocardial oxygen uptake from 14% to 22% in relation to the resting levels. In contrast, mean delta-values of metabolites ranged from 5% to 136% in relation to the respective A-V differences during the study. The greatest variation occurred during pacing and of all the metabolites lactate exchange varied most. A spontaneous variation in the degree of ischaemia during repeat stress tests might be the major reason for the metabolite variability. Changes in CSBF, however, tended to correlate inversely to the delta-aortocoronary sinus differences of substrates during pacing. Precision of chemical analysis and blood sampling technique were of minor importance for the variability. Since lactate exchange varied most, the study suggests that additional measurements should be made of more metabolites when assessing the efficacy of therapy by means of myocardial metabolism.

Alterations in myocardial uptake of glutamate and release of alanine after propranolol, nifedipine, and glyceryl trinitrate in coronary artery disease

We examined the effects of antianginal drugs on myocardial uptake of glutamate and release of alanine in patients with chronic effort angina. Thirty-three patients underwent two periods of atrial pacing, the second preceded either by no medication (controls) (n = 8), 0.1 mg/kg i.v. propranolol (n = 8), 30 mg nifedipine sublingually (n = 9) or 0.75 mg glyceryl trinitrate sublingually (n = 8). Before, during, and after each pacing period, coronary sinus blood flow (CSBF), oxygen uptake, and arteriocoronary sinus differences (ACs) of plasma glutamate and alanine were determined. In all groups of patients, arterial alanine concentration fell during the second test. Except for this fall, no metabolic change was seen in controls. Propranolol increased circulating arterial concentration and ACs values of glutamate throughout the test. Nifedipine did not change arterial glutamate concentration but decreased ACs glutamate before and after pacing. Glyceryl trinitrate decreased CSBF, oxygen uptake, and net myocardial uptake of glutamate before pacing despite unchanged arterial level and ACs values. Alterations of myocardial glutamate uptake after drugs may reflect metabolic effects of propranolol primarily exerted on extracardial sites and of nifedipine exerted on the myocardium itself, whereas changes after glyceryl trinitrate seem to be secondary to its cardiac unloading effect. Alterations in myocardial release of alanine were too small and inconsistent to be taken as drug effects.

Influence of nifedipine on coronary haemodynamics and myocardial metabolism in coronary artery disease

The effect of 30 mg sublingual nifedipine on cardiac metabolism and haemodynamics was studied during two identical periods of pacing in 11 patients with chronic coronary artery disease. The pace time to angina pectoris improved after nifedipine in 6 patients, deteriorated in 2 and was unchanged in 3. Nifedipine decreased blood pressure (12%), rate pressure product (10%) and coronary vascular resistance (17%) during pacing. Aorto-coronary sinus (A-Cs) oxygen difference decreased at rest (9%) and postpacing (10%) after nifedipine, although an opposite tendency in coronary sinus blood flow resulted in unchanged myocardial oxygen uptake throughout the study. Although mean myocardial lactate extraction after nifedipine was unchanged during pacing in the whole group of patients, it increased in 9 patients who showed a net lactate release at control pacing (from -50.9 +/- 33.5% to -35.9 +/- 30.2%, P less than 0.05). Nifedipine increased free fatty acid (FFA) extraction during pacing (from 1.5 +/- 12.9% to 17.4 +/- 13.1%, P less than 0.02) and uptake (from 1.8 +/- 8.5 to 11.1 +/- 10.6 mu mol min-1, P less than 0.05). Nifedipine influenced only glucose exchange significantly (46% decreased extraction) at 5 min postpacing. The A-Cs citrate gradient lessened 30-40% postpacing after nifedipine administration. Since the unloading effects of nifedipine did not alter myocardial oxygen uptake, the most important net haemodynamic finding was the decrease in coronary vascular resistance. Although no significant antianginal effect of a fixed dose of nifedipine was found, the increased uptake of FFA may reflect improved myocardial oxidative metabolism after nifedipine.

Myocardial glutamate and alanine exchanges related to carbohydrate metabolism in patients with normal and stenotic coronary arteries

Myocardial exchanges of glutamate, alanine, glucose, lactate, free fatty acids (FFA) and oxygen in resting state were determined in nine subjects (controls) without and in 28 patients with coronary artery disease (CAD). Patients with CAD showed increased myocardial glutamate uptake (2.51 +/- 0.60 mumol/min) and alanine release (1.25 +/- 0.60 mumol/min) compared to controls (glutamate uptake: 1.66 +/- 0.79 mumol/min; alanine release: 0.63 +/- 0.41 mumol/min). Myocardial glucose and lactate uptake was augmented in CAD patients, whereas FFA arteriovenous differences were decreased in patients with three-vessel-disease. The amount of glutamate taken up by the heart correlated positively to lactate uptake in all subjects (r = 0.84) and to external glucose utilization in patients with CAD (r = 0.72). Myocardial alanine release was positively related to glucose and lactate uptake in controls and in patients with only moderate CAD (one-vessel-disease). Glucose and FFA uptake correlated inversely in controls (r = 0.84), but not in CAD patients. A tight relation between exchanges of glutamate/alanine and carbohydrate metabolism in human heart is demonstrated. The data suggest altered myocardial substrate exchange towards augmented carbohydrate utilization in CAD patients in resting state. The results agree with in vitro and animal studies suggesting extraction of glutamate from the circulation to be of importance for maintaining carbohydrate consumption in chronic ischaemic heart disease.

Beneficial effect of a low-fat low-calorie diet on myocardial energy metabolism in patients with angina pectoris

8 patients with exertional angina pectoris were treated for 3 months with a low-fat, low-calorie diet. Serum cholesterol was reduced by 28% and body-weight by 7.9 kg on average. The effect of the dietary intervention was assessed by a heart metabolic study during pacing-induced tachycardia. After dietary treatment coronary sinus blood-flow and myocardial oxygen consumption were considerably reduced, but pacing time before angina developed increased. Other improvements were a reduction in lactate release during pacing, a reduction in citrate release during recovery, a reduction in alanine output during rest and recovery, and a lower uptake of glutamate. The results suggest a beneficial effect of low-fat, low-calorie dietary treatment on myocardial energy metabolism in patients with exertional angina pectoris.

Myocardial exchange of metabolites after nitroglycerin in patients with coronary artery disease

We studied the effects of sublingual nitroglycerin (dose range 0.5-1.0 mg) on cardiac metabolism in the resting state in 12 patients with chronic coronary artery disease. Seven patients with chronic coronary artery disease served as a control group. No patient from either of the groups experienced angina pectoris during the study. Reduced heart work after nitroglycerin was evident from a 34% decrease of oxygen uptake (P less than 0.001) and a 35% fall in coronary sinus blood flow (P less than 0.01). Nitroglycerin decreased lactate extraction by 30% (P less than 0.05), lactate uptake by 58% (P less than 0.025); glucose uptake by 47% (P less than 0.01) while net exchange of free fatty acids did not change. The aorto-coronary sinus difference of plasma citrate became increasingly negative (from -4 +/- 3 mumol/l to -8 +/- 2 mumol/l) (P less than 0.02) after nitroglycerin. In the control group coronary sinus blood flow and myocardial exchange of oxygen and substrates remained unchanged. Our results suggest a relatively increased myocardial utilization of free fatty acids compared with that of carbohydrates after nitroglycerin. This may in part be explained as an inhibition of glycolysis due to citrate accumulation. The study indicates that myocardial lipid-carbohydrate metabolism is disturbed in chronic coronary artery disease even in patients without clinical evidence of ischaemia in resting state and that nitroglycerin reverses this condition towards the metabolism of the normal heart.