Cardiac sympathetic activity in myocardial ischemia: release and effects of noradrenaline

Sympathetic overactivity in myocardial ischemia is closely associated with the progression of myocyte injury and the incidence of malignant arrhythmias. Adrenergic stimulation of the ischemic myocardium is predominantly due to increased local noradrenaline concentrations in the heart, whereas plasma catecholamine levels are of minor relevance. During the first few minutes of ischemia, efferent sympathetic nerves are activated. Excessive accumulation of noradrenaline, however, is prevented since adenosine, formed in the ischemic myocardium, suppresses exocytotic noradrenaline release, and released noradrenaline is rapidly removed as long as catecholamine reuptake is functional. With progression of ischemia to more than 10 min, the myocardium is no longer protected against excess catecholamine accumulation in the interstitial space, since local metabolic release mechanisms become increasingly important. This release, which is independent of central sympathetic activity and from extracellular calcium, occurs in two steps: First, noradrenaline escapes from its intracellular storage vesicles and accumulates in the cytoplasm of the neuron. In a second, rate-limiting step, noradrenaline is transported across the plasma membrane into the interstitial space, using the neuronal uptake carrier in reverse of its normal transport direction. As a consequence of local metabolic catecholamine release, extracellular noradrenaline reaches 1000 times the normal plasma concentration within 20 min of ischemia. Studies using acute and chronic sympathetic denervation and antiadrenergic agents demonstrate that local metabolic, rather than centrally induced noradrenaline release is critically involved in the progression of ischemic cell damage within the occurrence of ventricular fibrillation in early ischemia. Myocardial ischemia results in a temporary supersensitivity of the myocytes to catecholamines. This is due to a twofold increase of alpha 1- and a 30% increase of beta-adrenergic receptor number at the cell surface. The sensitization of adenylate cyclase during the first 20 min of total ischemia is followed by a rapid inactivation of the enzyme. The beta-adrenergic hyperresponsiveness to catecholamines is therefore limited to the first few minutes of ischemia. The deleterious combination of extremely high noradrenaline concentrations with a temporarily enhanced responsiveness to catecholamines of the tissue is thought to accelerate the propagation of the wavefront of irreversible cell damage within the ischemic myocardium. Moreover, the inhomogenous distribution of catecholamine excess within the heart is considered to promote malignant arrhythmias by unmasking and enhancing electrophysiological disturbances in early ischemia.

Activation of coagulation in acute cardioembolic stroke

The hematologic disorders in patients with acute cardioembolic stroke are not fully understood, and no reliable measures are available to identify patients at high risk for recurrent embolism. We analyzed coagulation and fibrinolytic functions in 22 patients with cardiogenic cerebral embolism less than or equal to 24 hours after onset and in 25 age-matched controls. The levels of antithrombin III, protein C, and alpha 2-plasmin inhibitor were significantly lower in the patients than in the controls (p less than 0.001, 0.02, and 0.05, respectively). In contrast, the plasma concentrations of thrombin-antithrombin III complex and crosslinked D-dimer were markedly higher in the patients than in the controls (p less than 0.01 and 0.001, respectively). At the time of admission, the plasma concentrations of thrombin-antithrombin III complex and crosslinked D-dimer in the eight patients at high risk for recurrent embolization (one with prodromal embolism, three with intracardiac thrombi, and four with recurrent embolization) were 2.8 and 3.5 times, respectively, higher than those in the 14 patients without recurrence or thrombus formation. The lowest concentration of crosslinked D-dimer in the eight patients at high risk for recurrent embolization was 600 ng/ml on admission. Our results suggest that patients with acute cardioembolic stroke have various degrees of consumption coagulopathy and that the plasma concentrations of thrombin-antithrombin III complex and crosslinked D-dimer can be useful indicators of those who are prone to recurrent embolization during this stage.

Coronary heart disease and diabetic retinopathy in newly diagnosed diabetes in Da Qing, China: the Da Qing IGT and Diabetes Study

In 1986, 110,660 of 281,589 residents aged 25-74 years in Da Qing, Hei Long Jiang Province of China, were surveyed. Based on the results of a 75-g oral glucose tolerance test, 630 subjects were found to have previously undiagnosed diabetes according to 1985 WHO criteria. Among them, 600 diabetics aged 35-74 years (288 men, 312 women) and 410 non-diabetics of similar age with normal glucose tolerance (207 men, 203 women) were examined to determine the prevalence of retinopathy and coronary heart disease (CHD) and to evaluate associated characteristics. Retinal examinations of 423 newly diagnosed diabetics showed that 15.4% had several microaneurysms and/or small intraretinal haemorrhage, 5.5% soft exudates, 7.1% hard exudates, and 2.3% proliferative retinopathy. Among 220 non-diabetics, 13.6% had one or two microaneurysms and/or small intraretinal haemorrhage, and only 1.4% had a few soft exudates; half of the non-diabetics with retinopathy had hypertension. CHD, according to Minnesota coding (1.1-1.3, 5.1-5.3 and 7.1) of resting electrocardiograms, was ten times more frequent in the diabetics (3.59%) than in the controls (0.32%), after adjusting for age and sex. Multiple regression analysis showed that plasma glucose concentration was a risk factor for retinopathy after adjusting for age, sex, body mass index (BMI), smoking and blood pressure. Two-hour plasma glucose concentration (after adjusting for age, sex, BMI, smoking and blood pressure) and blood pressure (after adjusting for age, sex BMI, smoking and 1-h or 2-h plasma glucose level) were associated with CHD among the diabetics and non-diabetics and among the diabetics alone. Thus, both micro- and macrovascular complications occur frequently in previously undiagnosed Chinese diabetics and the frequency of CHD is markedly increased compared to the low frequency among Chinese non-diabetics.

[Pathogenetic characteristics of the development of arrhythmia in patients with ischemic heart disease]

ACTH, hydrocortisone and cyclic nucleotides levels, beta-receptors sensitivity, lipid peroxidation (LPO), antioxidant system, hemodynamics were investigated in 93 coronary patients without myocardial infarction in the presence of cardiac arrhythmia and after its correction. The clinical and laboratory findings indicate that it is primarily LPO activation and LPO products excessive accumulation in the blood that are responsible for arrhythmia emergence. Experimental data support these results by showing possibility of cardiac arrhythmia onset due to LPO products which raise the density of Na-Ca channels and inhibit the activity of Ca-dependent ATPase.

Prevalence and correlates of angina pectoris in the Italian nine communities study. Research Group ATS-RF2 of the Italian National Research Council

We investigated the prevalence and correlates of angina pectoris in 6573 men and women aged 20-59 participating in the Italian National Multicenter Study on Risk Factors for Arteriosclerosis. In both sexes, the prevalence of angina pectoris, as assessed by the Rose questionnaire, increased sharply with age (from 0.8% to 5.1% for men and from 1.7% to 6.9% for women). In all age groups, there was a higher prevalence of angina pectoris for women than for men. In men, a strong positive association was found between angina pectoris and myocardial infarction (both by self-report and electrocardiographic documentation) and self-reported dyspnea. In women, myocardial infarction (self-reported), electrocardiographic-documented myocardial ischemia, intermittent claudication, and dyspnea were all associated with angina pectoris. In both sexes, angina pectoris was positively associated with body mass index. Males with diabetes had two times the prevalence of angina pectoris as males without diabetes; in females, diabetes was only weakly associated with angina pectoris. None of other major ischemic heart disease risk factors (blood pressure, serum lipids, or smoking) was associated with angina pectoris.

Coronary artery bypass operation in dialysis patients

To analyze the short- and long-term morbidity and mortality among maintenance dialysis patients who have undergone coronary artery bypass operations, we identified 25 such patients at the Mayo Clinic and three recently published large single-center studies that provided sufficient detail for meaningful comparison. Two independent observers reviewed the new information with regard to pertinent historical, clinical, and laboratory data. The perioperative mortality was 20%. Among the perioperative survivors, 1- and 2-year survival rates were 95% and 77%, respectively. The 3-year actuarial survival was 70%. Uniformly, the symptoms diminished, and the need for antianginal medication was decreased. In the three other large published series, the perioperative mortality ranged from 3 to 20%, and coronary artery bypass performed earlier after the onset of the symptoms seemed to result in a lower perioperative mortality. We conclude that elective coronary artery bypass in dialysis patients is associated with acceptable short-term morbidity and mortality and effective relief of symptoms. Surgically treated patients may have a survival advantage. Thus, we advocate aggressive early investigation and surgical treatment of these patients.

[Secretion of calcium-regulating hormones in diabetes mellitus]

At present great attention is paid to Ca2+ metabolic derangement in the pathogenesis of cardiovascular alterations. Some researchers interpret this derangement as change in the ratio of parathyroid secretory activity and thyroid C-cell activity. For this purpose the blood levels of parathormone and calcitonin were investigated by radioimmunoassay with simultaneous recording of lower limb hemodynamic indices in 136 patients with diabetes mellitus. Change of elasticity of major vessels, a decrease in the reserve blood flow, marked to a greater extent in patients over 40 and combined with essential hypertension, were observed. An increase in the blood levels of parathormone and calcitonin was also observed. Direct correlation was established in both age groups between the levels of parathormone and calcitonin and hemodynamic indices.

The physical examination in acute cardiac ischemic syndromes

The physical examination in acute cardiac ischemia remains a valuable tool when done with skill. Ischemia without infarction alters cardiac function, and the physical examination yields findings that reflect these changes. Ischemia with infarction alters structure and function, resulting in physical findings that are usually more dramatic and of longer duration, sometimes permanent. Carefully done, the physical examination provides information that helps in management of the immediate course, predicts prognosis, and allows for better interpretation of cardiovascular tests, both invasive and noninvasive.

[Participation of the prostacyclin-thromboxane system in the mechanisms of prevention of arrhythmia caused by occlusion of the coronary artery in adapted rats]

It was found, that adaptation of rats to cold and physical exercise prevented ventricular fibrillation, caused by the occlusion of the left anterior coronary artery. An adaptation to cold only or to physical exercise do not prevent ventricular arrhythmias. An significant increase of prostacyclin/thromboxane index in plasma and heats was estimated in rats adapted to cold and physical exercise in relation to control non-adapted group in condition of functional rest or acute myocardial ischemia. It was assumed that an increase of prostacyclin/thromboxane ratio has a significant role in antiarrhythmic action of adaptation.

[Tactics of the surgical treatment of combined occlusive diseases of the coronary arteries, the abdominal aorta and the arteries of the lower extremities]

On the basis of experience in reconstructive operations on 250 patients with combined affection of the coronary arteries, abdominal aorta, and arteries of the lower limbs the authors discuss the diagnostic and tactical features of surgical management of these patients. The article dwells upon the necessary preoperative diagnostic algorithm as well as that in tactical variants of surgical treatment: (1) one-stage reconstructive operations on several vascular beds; (2) successive stage-by-stage treatment of patients with combined vascular pathology; (3) reconstructive vascular intervention on only one of the vascular beds. Correct practical solution of all these problems allowed the authors to reduce postoperative lethality to 5.4% among this grave contingent of patients with combined vascular pathology.

Influence of hypoxia on adrenergic modulation of triggered activity in isolated adult canine myocytes

Although findings from several reports suggest that nonreentrant or focal mechanisms contribute to the genesis of arrhythmias during early ischemia, the contribution of triggered activity arising from early or delayed afterdepolarizations has not been resolved. We have previously demonstrated that beta- but not alpha-adrenergic stimulation induces afterdepolarizations and triggered activity in isolated normoxic myocytes. In the present study, the influence of the extent of cellular derangements as well as increases in [K+]o on alpha- and beta-adrenergic-mediated afterdepolarizations and triggered activity was evaluated. Adult canine myocytes were exposed to one of the following experimental conditions with simultaneous intracellular transmembrane action potential recordings: 1) low PO2 (less than 10 mm Hg, obtained using a specially designed hypoxic chamber) and low (6.8) pH; 2) low PO2, low pH, and high extracellular potassium ([K+]o) (10 mM); or 3) severe metabolic inhibition with cyanide (10(-6) M). Cells from each group were superfused with either the alpha-agonist phenylephrine (10(-5) or 10(-7) M, with 10(-5) M nadolol) or the beta-agonist isoproterenol (10(-6) M). Moderate changes in the action potentials were observed under conditions 1 and 2 (moderate hypoxia), whereas marked but reversible changes were observed with cyanide (severe metabolic inhibition). During moderate hypoxia in normal [K+]o, delayed afterdepolarizations or triggered activity were elicited by both alpha- (12 of 13 cells) and beta-adrenergic (five of five cells) stimulation. Increasing [K+]o during moderate hypoxia completely abolished the afterdepolarizations induced by alpha-adrenergic stimulation and prevented the occurrence of triggered activity. In contrast, the influence of beta-adrenergic stimulation was only attenuated by an increase in [K+]o. Exposure to cyanide completely prevented the induction of afterdepolarizations and triggered activity by both alpha- and beta-adrenergic stimulation. Our findings indicate that moderate hypoxia in normal [K+]o is associated with the development of adrenergic-mediated afterdepolarizations and triggered activity. In contrast, accumulation of [K+]o or severe impairment of cellular metabolism is accompanied by inhibition of adrenergic-mediated afterdepolarizations and triggered activity.

Coronary artery bypass grafting in a patient with cryoglobulinemia

Coronary artery bypass grafting (CABG) was performed in a patient with cryoglobulinemia. In order to decrease the concentration of cryoglobulin, the patient underwent double filtration plasmapheresis (DFPP) pre- and postoperatively as well as during cardiopulmonary bypass. Bypass surgery was performed under total cardiopulmonary bypass, moderate systemic hypothermia, and ventricular fibrillation without aortic crossclamping. No adverse effects of cryoglobulin appeared during the peri- and postoperative course. Technical considerations for open heart surgery in patients with cryoglobulinemia are described.

Imprecision of the clinical diagnosis of coronary heart disease in epidemiological studies and atherogenesis

Coronary heart disease (CHD) is an imprecise diagnosis associated with a substantial diagnostic error and provides an erroneous assessment of the morbidity and mortality of myocardial ischemia and of severe coronary atherosclerosis. Due to the inability to measure the severity of atherosclerosis during life, epidemiologists frequently use the incidence of CHD as a surrogate monitor of severe atherosclerosis. It is therefore important in clinical epidemiological studies to appreciate the degree of inaccuracy of CHD statistics, which detracts from the value of such studies and their reliability.

Hemodynamic response to dietary sodium loading in essential hypertension studied with Doppler echocardiography

The cardiac response to dietary salt loading was assessed by Doppler echocardiography during various sodium intakes (52-345 mEg per day) in 30 patients with essential hypertension. The Mitral flow velocity integral in the rapid filling phase (IntR) and the atrial contraction phase (IntA) was measured from the transmitral flow pattern, and the sum of IntR and IntA (IntR + IntA), the ratio of IntA to IntR (IntA/IntR), cardiac output (CO) and total peripheral resistance (TPR) were calculated. With salt loading, the mitral flow pattern remained almost unchanged in the nonsalt-sensitive (NSS) patients. Fourteen of the 19 salt-sensitive (SS) patients showed significant increases in IntR + IntA and CO with salt loading (IntR + IntA, from 13.9 +/- 2.8 to 17.9 +/- 3.6 cm, p less than 0.01; CO, from 6021 +/- 2130 to 8305 +/- 1699 ml/min, p less than 0.01), and were termed "salt-sensitive CO-dependent" (SS [COdep]), suggesting that the apparent pressor response to sodium loading was mediated by an increased CO. In the remaining five SS patients termed "salt-sensitive CO-independent" (SS [COindep]), IntA/IntR increased significantly with sodium repletion (from 0.66 +/- 0.23 to 0.90 +/- 0.31, p less than 0.01), without a significant change in IntR + IntA. Increments in IntA/IntR observed in the SS [COindep] patients were considered to be due to an elevation of total peripheral resistance (TPR), since changes in IntA/IntR were significantly correlated with those in TPR in all subjects (r = 0.617, p less than 0.01).

Familial aggregation of non-insulin dependent diabetes and coronary heart disease are accompanied by different effects on serum lipids, lipoproteins and apolipoproteins

This study was designed to investigate whether the presence of non-insulin-dependent diabetes mellitus (NIDDM) or coronary heart disease (CHD) in probands have different effects on serum lipid, lipoprotein and apolipoprotein concentrations in the first-degree relatives. Altogether 161 probands (114 men, 47 women) and 788 first-degree relatives of these probands (174 brothers, 246 sisters, 180 sons, 188 daughters) were included in the analyses. The presence of NIDDM in the proband was associated with lowered total, LDL and HDL cholesterol and apolipoprotein A1 and elevated total triglyceride levels in the brothers (P less than 0.05) and elevated total and LDL cholesterol levels in the sisters (P less than 0.05). Total LDL and VLDL cholesterol and apolipoprotein B were higher (P less than 0.05) and HDL/total cholesterol ratio and apolipoprotein A1/B ratio lower (P less than 0.05) in the daughters of the nondiabetic and diabetic probands were pooled, CHD in the proband was associated particularly with low apolipoprotein A1/B ratio. In conclusion, (1) the presence of NIDDM in the proband appears to be associated in siblings with more profound lipid and lipoprotein changes (especially low HDL cholesterol and high total triglycerides) than a history of CHD in the proband, (2) a history of CHD in the proband is associated in children with apolipoprotein changes favouring atherosclerosis (low apolipoprotein A1, high apolipoprotein B, low apolipoprotein A1/B ratio). Different effects of a history of NIDDM and CHD in the proband on lipid, lipoprotein and apolipoprotein levels in the first-degree relatives warrants more population-based studies.

[Central hemodynamics, kidney functions and water-salt metabolism in patients with ischemic heart disease and an increased venous blood return to the heart]

A study is presented of the central hemodynamics, renal function and water-salt metabolism in 42 patients with ischemic heart disease and chronic circulatory insufficiency (grades I and II) and revealed a deterioration of these indices in this categories of patients manifested in a retention of sodium, deterioration of central hemodynamics after increase of venous inflow.

[Comparative effectiveness of psychotropic drugs in patients with chronic ischemic heart disease]

As many as 348 courses of psychotropic and antianginal chemotherapy were performed for coronary disease confirmed angiographically. Hypochondriac patients were resistant to the drugs, depressive states and anxiety showed the best response. Tranquilizers and neuroleptic agents proved effective in anxiety, neuroleptics in cardiophobia and hypochondria, antidepressants in depression and asthenia. The addition of psychotropic drugs to antianginal therapy produced a positive effect on cardiac pain with antidepressants benefit ranking first, neuroleptics second and tranquilizers third. Being moderate and transient, treatment-related side effects did not cause the treatment discontinuation.

Determinants of ventricular arrhythmias in cardiac hypertrophy

Ventricular arrhythmias occur with increased frequency in both experimental and human cardiac hypertrophy. Although the process of hypertrophy itself may be arrhythmogenic, other factors may contribute to the high prevalence of arrhythmias in hypertensive patients with left ventricular hypertrophy (LVH). Disease of the large epicardial coronary arteries or of the small intramyocardial vessels (coronary microangiopathy) may lead to myocardial ischemia and thus predispose to arrhythmia. Myocardial fibrosis, a common sequelae of cardiac hypertrophy, has also been shown to be associated with ventricular arrhythmias in experimental models. Other possible determinants of ventricular arrhythmias in this group of patients include metabolic abnormalities; studies relating to the importance of hypokalemia in particular have yielded conflicting results. Thus a number of factors may combine to explain the high prevalence of ventricular arrhythmias in hypertensive patients with LVH.

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Studies of myocardial protection in the immature heart. I. Enhanced tolerance of immature versus adult myocardium to global ischemia with reference to metabolic differences

This study compares the metabolism and functional responses of adult and immature hearts to a standard ischemic insult. Ten adult dogs (25 to 27 kg) and 10 puppies (6 to 10 weeks old) underwent 45 minutes of aortic clamping on bypass. Preoperative and postoperative ventricular performance (Starling curves), biochemical factors, and water content were measured. Global ischemia in adults produced a 30% mortality rate (3/10) and low output syndrome in survivors (33% recovery of stroke work index). Conversely, all puppies survived and stroke work index returned to 85% of control, with less edema developing (0.4% versus 2% water gain, p less than 0.05). Puppies expended comparable glycogen stores but used more glutamate (15.4 versus 8.6 mumol/gm dry weight), produced more alanine (18.9 versus 6.4 mumol, p less than 0.05), succinate (19 versus 8.2 mumol, p less than 0.05), and malate (2.6 versus 0.15 mumol, p less than 0.05) during ischemia, and recovered better postischemic aerobic metabolism (410 versus 255 nmol tissue pyruvate, p less than 0.05). We conclude that tolerance of immature hearts to ischemia is related to amino acid utilization by transamination and increased substrate level phosphorylation, as occurring in diving mammals, suggesting retention of intrautero adaptive mechanisms.