Impaired myocardial perfusion and perfusion reserve associated with increased coronary resistance in persistent idiopathic atrial fibrillation

AIMS

Patients with atrial fibrillation (AF) present with symptoms of myocardial ischaemia despite exclusion of coronary artery disease. A small vessel disease has been suggested. We quantified myocardial perfusion, perfusion reserve, and coronary vascular resistance (CVR) in AF patients using positron emission tomography (PET).

METHODS AND RESULTS

Twenty-five male patients (age: 58 +/- 13 years) with persistent idiopathic AF were compared with 13 age- and risk-matched male controls (age: 56 +/- 8 years). Using H(2)(15)O-PET, myocardial blood flow (MBF) was quantified at rest, at hyperaemia (adenosine), and during cold-pressor-testing (CPT). Scans were repeated 4.1 +/- 2.3 months after cardioversion in 10 AF patients. In AF, resting MBF (0.95 +/- 0.19 vs. 1.14 +/- 0.22 mL/min/mL; P = 0.009), hyperaemic MBF (2.07 +/- 0.80 vs. 3.33 +/- 0.78 mL/min/mL; P < 0.001), and MBF under CPT (0.90 +/- 0.25 vs. 1.14 +/- 0.25 mL/min/mL; P < 0.014) were significantly reduced compared with matched controls. Hyperaemic CVR was increased in AF (47 +/- 21 vs. 29 +/- 7 mmHg x mL/min/mL; P = 0.012) but unchanged at rest and under CPT. After cardioversion, resting MBF and MBF under CPT in AF were similar to matched controls, however, hyperaemic MBF and CVR were not recovered.

CONCLUSION

In AF, MBF at baseline, at hyperaemia, and at CPT is reduced, whereas CVR under hyperaemic conditions is increased. Following electrical cardioversion, these findings are partly reversible and therefore most likely secondary to the arrhythmia.

Vasoactive peptides during long-term follow-up of patients after cardiac transplantation

BACKGROUND

Vasoactive peptides are accepted indicators of the degree of heart failure and its progression or improvement following medical therapy. Normalization of cardiac hemodynamics by cardiac transplantation (HTx) may lead to normalization of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) plasma levels shortly after the procedure.

METHODS

Long-term follow-up was done for 14 consecutive patients, 12 men and 2 women, 49 years of age (range 24 to 64 years). ANP and BNP were measured by radioimmunoassay (RIA) in central venous plasma samples (before breakfast, at steady state) at the following intervals after HTx: 7 to 30 (1), 31 to 60 (2), 61 to 90 (3), 120 to 180 (4) and 210 to 365 (5) days.

RESULTS

During follow-up, ANP decreased significantly within 2 months after HTx and continued of this level, whereas BNP decreased continuously without reaching normal values. The mean ratio of ANP:BNP increased from 3.23 to 8.01 during follow-up. Whereas right atrial pressure (RAP), right ventricular pressure (RVP), right ventricular end-diastolic pressure (RVEDP) and pulmonary capillary wedge pressure (PCWP) did not change during follow-up, cardiac output (CO) improved slightly, but significantly from 5.21 liters/min to 5.9 liters/min (p = 0.035).

CONCLUSIONS

Normalization of left ventricular function after orthotopic HTx does not induce an early diminution of ANP and BNP plasma levels to normal concentrations. Although elevated ANP concentrations showed only minimal changes within 1 year, BNP decreased significantly as early as 2 months after HTx, without reaching normal values during the year of follow-up. Also, the ratio of ANP and BNP increased significantly from 3.23 to 8.01. These results demonstrate the contribution of other factors beyond cardiac function that determine the levels of these peptides.

Ischemic versus idiopathic cardiomyopathy: differing neurohumoral profiles despite comparable peak oxygen uptake

OBJECTIVE

We tested the hypothesis that neurohormonal and immunological activation differs in ischemic and idiopathic dilated cardiomyopathy since recent intervention trials indicate that ischemic cardiomyopathy seems to carry a worse prognosis than idiopathic cardiomyopathy of comparable clinical severity.

METHODS

In ten patients with ischemic cardiomyopathy undergoing spiroergometric evaluation venous levels of norepinephrine, epinephrine, renin, angiotensin, atrial natriuretic peptide as well as soluble interleukin-2-receptor were determined before, during and 10 min after exercise. Results were compared to sixteen patients with idiopathic cardiomyopathy with similar peak oxygen uptake (13.3+/-3 vs. 13.6+/-3 ml/kg/min; P=ns).

RESULTS

In ischemic patients, norepinephrine, angiotensin, and interleukin-2 receptor levels were significantly higher before, during and after exercise. Interleukin-2-receptor levels correlated with angiotensin.

CONCLUSIONS

We conclude that in ischemic as compared to idiopathic cardiomyopathy, a more pronounced activation of the sympathetic, renin-angiotensin and T-cell immune system is present at rest, during and after exercise. These data may contribute to explain differences in response to intervention and in prognosis. They warrant further investigation.

[Proinflammatory cytokines and cardiac pump function]

In situations of depressed myocardial function, the role of immunological mechanisms has been studied recently. In different pathophysiological situations, such as chronic heart failure, open heart surgery with extracorporal circulation, cardiac transplantation, myocardial infarction and angina pectoris, patterns have been described with elevation of proinflammatory cytokines, such as tumor necrosis factor-alpha, interleukin-1, interleukin-6, and reversible myocardial dysfunction, which may represent a final common pathway. The available data suggest a modulation of important determinants of pump function, i.e., contractility, preload, afterload, and heart rate, by cytokines. Potential mechanisms include the beta-adrenoceptor- and nitric oxide pathway, as well as a direct impact on intracellular calcium homeostasis. Interventional strategies based on this understanding are beginning to emerge.

Interleukin-6 correlates with hemodynamic impairment during dobutamine administration in chronic heart failure

Proinflammatory cytokines have been implicated in the pathophysiology of chronic heart failure. We determined mixed venous levels of interleukin-6 (IL6) in 18 heart transplant candidates before, 1, 4, and 24 h after initiation of dobutamine infusion (3 micrograms/kg/min) during hemodynamic evaluation. During the first 4 h of dobutamine, systemic vascular resistance decreased (1358 to 1024 dyn x s x cm-5, P = 0.01) while cardiac index (2.3 to 2.9 l/min/m2, P = 0.008) increased. Both returned to baseline after 24 h. IL6 was elevated at baseline compared to age-matched controls (1.5 (0/4.3) vs. 0 (0/0.5) P = 0.003). There was an increase in IL6 from 1.5 (0/4.3) to 3.6 (0.3/5.3) pg/ml after 24 h (P = 0.04). We found higher IL6 levels in the sicker half of patients as defined by pulmonary capillary wedge pressure > 24 mmHg (P = 0.005), mean pulmonary arterial pressure > or = 35 mmHg (P = 0.01), right atrial pressure > 13 mmHg (P = 0.02), and heart rate > or = 87/min (P = 0.02) as well as mean arterial pressure < 82 mmHg (P = 0.005). In conclusion, in this pilot study IL6 correlates with the severity of chronic heart failure during low dose dobutamine infusion.

Diagnostic assessment of macrophage phenotypes in cardiac transplant biopsies

Forty-one endomyocardial biopsies of the right interventricular septum have been investigated in 24 immunosuppressed patients after orthotopic heart transplantation. Monoclonal antibodies 27E10, 25F9, and RM3/1, which react with different macrophage phenotypes, and antisera MRP-8 and MRP-14, specific for proteins expressed on endothelial and monocyte cell surfaces in inflammation as well as markers for CD4+ and CD8+ T-lymphocytes, were employed in an indirect immunoperoxidase staining technique. This methodology permits more physiological recognition of the inflammatory process within the myocardium. It was possible to verify and to distinguish acute early, late and down-regulatory stages of inflammation in 33 biopsies (80%). No evidence of inflammation was found in seven biopsies (17%). Conventional histopathology with haematoxylin-eosin and Masson's trichrome was performed simultaneously, and demonstrated inflammation to be present in 23 of 41 biopsies (56%). An important findings is that CD4+ and CD8+ lymphocytes were absent in 15 of 41 specimens (37%) although there was inflammation proven by the presence of different macrophage phenotypes. The results indicate the necessity of long-term serial investigations of the physiological role of specific inflammatory macrophage phenotypes during the rejection process. It is concluded that the phenotyping of macrophage and endothelial cell differentiation antigens offers a sensitive approach to assess diagnosis of myocardial inflammation as a consequence of ongoing rejection in cardiac allografts.

Phenotyping of macrophages with monoclonal antibodies in endomyocardial biopsies as a new approach to diagnosis of myocarditis

Cryostat sections of endomyocardial biopsies from 53 patients (mean age 41 +/- 5 years, 38 male and 15 female) clinically indicated to suffer from myocarditis were stained using monoclonal antibodies against subpopulations of T-lymphocytes and macrophages and with polyclonal rabbit-anti-human sera marking two calcium-binding proteins expressed by monocytes and macrophages appearing in inflammatory sites only. No inflammatory infiltrate cells were found in 13 cases (25%). Mononuclear cell infiltrates were present in 40 cases (75%). Ten biopsies showed a predominance of macrophages bearing the marker 27E10, characteristic for an early acute inflammation and 18 biopsies contained 25F9 positive macrophages, characteristic for a late stage of inflammation. An intermediate type of inflammation with both macrophage types present was found in 12 patients. Patients with immunohistologically confirmed myocarditis had atrial, ventricular or combined forms of arrhythmias (78%), scars in the vectorcardiogram (100%) and radiological evidence of cardiomegaly (36%). In conclusion, typing and endomyocardial biopsies for macrophage subpopulations is a sensitive new approach to assess the diagnosis of myocarditis.

[Clinical vectorcardiography: the Fritz-Schellong commemorative lecture]

The continuous and direct registration of the vectorcardiogram was realized by cathode-ray oscillographic methods by F. Schellong in 1937 and hence introduced into clinical diagnostics. The following development of different lead systems resulted in the standardization of the corrected orthogonal Frank system, which yielded almost identical information when compared to the Schellong system. The advantages of this continuous registration of the 3-dimensional course of depolarization concern the detection of atrial and ventricular hypertrophy, because the sensitivity, as well as the specificity, of the vectorcardiogram are superior to the ECG. Possibilities of diagnosing myocardial infarction are considerably improved with regard to sensitivity, especially of scars with dorsal and inferior localization, as well as multiple events and simultaneous disturbances of fascicular and ventricular conduction. In addition, even multiple and small defects e.g. in cardiomyopathy or myocarditis, can be detected.

[Heart rate and contractile reserve of the aging heart]

In standardized experiments on both conscious and anaesthetized young (n = 11) and old (n = 7) dogs differences in haemodynamics, contractility and myocardial oxygen consumption correlated to age were evaluated. Under resting conditions no significant differences were observed. Following stimulation with catecholamines young (n = 6), and old (n = 6) dogs displayed an almost parallel increase in (dp/dt) max. After administration of orciprenalin, the maximum increase in heart rate was similar in both groups of animals; however, a significant difference in the maximum heart rate following atropine was observed, which was significantly lower in old than in young animals. The decreased performance of the aged myocardium does not appear to be predominantly due to an age-dependent reduction of the contractility reserve. It could result from a deficient sympathetic stimulation of the heart.

[Comparative studies on the anti-arrhythmic and anti-fibrillatory effectiveness of verapamil and nifedipine following acute coronary artery occlusion and reperfusion]

The ability of the two calcium-antagonists Verapamil and Nifedipine to reduce ventricular electrical instability following acute transient coronary artery occlusion and release and to prevent ventricular arrhythmias, particularly fibrillation, was evaluated on a total of 25 anaesthetized and artificially ventilated dogs. In all animals repeated coronary occlusions, lasting 20 min each, with a reperfusion period of 120 min between subsequent ligations, were performed. Time course and extent of ventricular ectopic activity were continuously registered, and the changes in ventricular vulnerability were assessed by measuring the ventricular fibrillation threshold at different times both after coronary artery occlusion and reperfusion. Verapamil displayed strong antiarrhythmic and antifibrillatory action on ventricular arrhythmias during occlusion. Ventricular tachycardia and fibrillation were completely prevented during phase la of arrhythmia (2nd to 10th min after coronary artery occlusion) and significantly reduced during phase lb (15th to 20th min after coronary artery occlusion). By contrast, Nifedipine failed to exert any antiarrhythmic and antifibrillatory effect, respectively. Following release of coronary artery occlusion, none of the compounds proved to reduce the frequency of ventricular fibrillation immediately after the onset of reperfusion. However, either drug was able to accelerate significantly the increase in the ventricular fibrillation threshold during the early post-reperfusion period. The different antiarrhythmic and antifibrillatory action of Verapamil and Nifedipine after coronary artery occlusion can be assumed to result from differences in the electropharmacological properties of these compounds, whereas the enhancement of the electrical stability of the myocardium after release of coronary artery occlusion may be due to "cardio-protective" effects of these drugs.

Beta-adrenoceptor blockade in stress due to oral surgery

1 The effects of a single oral dose of 5 mg pindolol (P) and 100 mg metoprolol (M) were assessed in a double-blind study in 30 patients undergoing oral surgery. 2 Systolic and diastolic blood pressures and heart rate were reduced 90 min after oral medication and did not exceed initial values at rest during the procedure. 3 Noradrenaline, adrenaline and c-AMP concentrations did not differ at any time from the control values at rest after P, but were increased after local anaesthesia and during oral surgery after M as were the metabolic responses reflected by plasma concentrations of glucose and free-fatty acids. 4 Plasma levels of ACTH and cortisol showed the typical increase during the procedure, being independent of beta-adrenoceptor blockade. In contrast to the cardioselective antagonist M, prophylactic administration of the non-selective drug P prevented the sympathetic and metabolic responses to the stress of oral surgery. 5 Hypothalamic and adrenal stimulation were not reduced by either selective or non-selective beta-adrenoceptor blockade.

Management of cardiac arrhythmias with tiapamil

37 patients with either chronic atrial fibrillation (AF), atrial premature beats (APBs) or ventricular premature beats (VPBs) received tiapamil as antiarrhythmic treatment. Tiapamil reduced A-V conduction by an average 20% in the group with AF (10 patients), the magnitude of response being dependent on the initial ventricular rate. In 3 of the 7 patients with APBs, the frequency of ectopic beats was reduced following a single i.v. injection of 1 mg/kg tiapamil. In patients with VPBs (n = 20), tiapamil (i.v. injection of 1 mg/kg followed by 4-hour i.v. infusion of 50 micrograms/kg/min in 10 patients) reduced ectopic beats by 30-50% in 6 cases, these all being patients who had not responded to previous antiarrhythmic therapy. The antiarrhythmic effect was maintained by i.v. infusion of 50 micrograms/kg/min for 4 h. The antiarrhythmic effect of tiapamil consists essentially in slowing A-V conduction and reducing chronic VPBs.

[Age dependence of increase in heart rate after vagolysis (author's transl)]

Age dependent decrease of heart rate in sinus rhythm at rest was shown under clinical and experimental conditions and correlated with a decrease of sympathetic storage granula and membranes indicated by the tissue concentrations of c-AMP, which can be regarded as a messenger at the receptor sites. A slower maximal heart rate after Atropine and a reduced increase during oral medication with Ipratropium bromide can be explained by a reduced cardiac sympathetic threshold. The mentioned age dependent differences of the sympathetic stimulation can not be deduced to myocardial changes, because CPK and CK-MB activities were similar in the different age groups.

[Antiarrhythmic therapy with flecainide in acute experimental myocardial infarction (author's transl)]

Clinical and experimental studies indicate that ventricular arrhythmias, especially ventricular fibrillation, are in almost all cases the mechanism for sudden death occurring during the first 24 hours after the onset of an ischaemic myocardial event. Therefore a higher survival rate seems to depend on advances in antiarrhythmic therapy. The present study investigates the efficacy of the new local anaesthetic compound Flecainide in reducing or preventing ventricular arrhythmias and primary ventricular fibrillation, using a standardized experimental canine preparation. Our findings demonstrate that ventricular arrhythmias due to severe transmural myocardial infarction are reduced by 80-90% following the application of Flecainide. In some cases a complete abolition of the arrhythmias can be observed. The striking reduction in ventricular ectopics includes decreases in ventricular salves and R-on-T phenomena, which may lead to sudden death by precipitating ventricular fibrillation. The beneficial antiarrhythmic and antifibrillatory actions of Flecainide affect only the arrhythmias resulting from transmural necrosis of the myocardium ("in-hospital arrhythmias", 2nd-phase arrhythmias"), whereas the incidence of early ventricular arrhythmias, especially ventricular fibrillation occurring in the very inception of myocardial ischaemia ("pre-hospital arrhythmias", "1st-phase arrhythmias") is not prevented. Changes in hemodynamics and contractility due to Flecainide are not severe, even in myocardial infarction. Thus, our results indicate that the application of Flecainide in acute myocardial infarction in man may be successful in reducing therapy-resistant ventricular dysrhythmias.

[Combination treatment of atrial arrhythmias with quinidine-verapamil]

Between 1977 and 1979, a combined antiarrhythmic therapy with Quinidine and Verapamil was used to treat 66 patients (aged 16 to 69 years) with chronic atrial arrhythmias of different etiology. In 60% of the 43 cases with atrial fibrillation the combined therapy was effective in reversing atrial fibrillation to regular sinus rhythm. The frequency of successful responses to Quinidine - Verapamil amounted to more than twice compared with earlier therapeutic results with Quinidine only. In 65% of the 23 cases with atrial extrasystoles or atrial tachycardias a significant reduction of the ectopics could be achieved or a regular sinus rhythm could be established. Thus, the combined therapy with Quinidine - Verapamil is very effective in abolishing chronic atrial arrhythmias, especially atrial fibrillation.

[Clinical study on stress protective action of cloxazolam in jaw surgery in double blind comparison to placebo (author's transl)]

An investigation in 50 patients has shown that biochemical measurements of dopamine-beta-hydroxylase (DBH), ACTH and cortisol as well as the concentration of glucose and insulin signal a reduction of surgical stress under the medication of the tranquilizer 10-chloro-11b-(2-chlorophenyl)-2,3,5,6,7,11b-hexahydrobenzo[6,7]-1,4-diazepino[5,4-b]oxazol-6-one (cloxazolam, MT 14-411). There was an inhibition of the DBH-increase during the surgical procedure and an inhibition of the ACTH- and cortisol-secretion before and during surgery as well as a reduction of the insulin antagonizing effect during sympathicoadrenal stimulation. With the exception of a sedative action no other side effects have been observed.

[The new calcium antagonist Ro 11-1781 in the treatment of ventricular tachycardia due to atrial fibrillation]

In 9 patients with tachyarrhythmia and atrial fibrillation the effect of the i.v. application of the calcium antagonist Ro 11-1781 on the av-conduction was investigated. All patients received 1 mg/kg during 2-3 minutes. A significant decrease of the ventricular rate at the end of the injection period was noted. The maximal decrease of the av-conduction of 10-32 % of the initial ventricular rate was observed 5-10 min after the injection. During 60 min the initial heart rate before application of the drug was not yet reached again. The registrations prove the inihibiting effect of Ro 11-1781 on av-conduction in atrial fibrillation, which was sufficient for therapeutic use in our cases concerning the reduction of heart rate and duration of the effect. No serious side effects were observed.

[Catecholamine metabolism. Physiopathology and pathobiochemistry]

Metabolic studies on isolated rat organs showed that vanillyl mandelic acid (VMA) is dehydrogenated by liver homogenate and suspension of pseudomonas fluorescens. In the 100000 g supernatant fraction of homogenated rat kidneys enzymatic activity was sufficient for kinetic studies and the examination of substrate specificity, pH dependence and changes with age and sex of rats. Norepinephrine secretion and resorption may be influenced by antiarrhythmic drugs in vivo: after lidocaine, there was no change of the tyramine dependend norepinephrine depletion of rat hearts, Verapamil inhibited the uptake of norepinephrine by rat hearts. Immobilisation of the animals led to a significant decrease in the myocardial levels for norepinephrine and epinephrine, which was antagonised by recreation of 24 hours. Adumbran prevented the catecholamine depletion, so that the influence of the limbic system may be important for the mediation of sympathetic stimuli.

CLINICAL STUDIES

Emotional stress was shown to lead to an elevated plasma level of norepinephrine, cortisole and free fatty acids. In patients undergoing surgery, the application of Valium and Fortral inhibited these stress reactions. After physical stress, which did not lead to significant changes of the catecholamine level in plasma of healthy volunteers, there was an elevated norepinephrine plasma level in patients with cardiac failure, which could be prevented by different antiarrhythmic drugs. The excretion of norepinephrine and VMA of these patients was also increased. It was shown, that sinus rate rose according to norepinephrine levels in plasma in this group, which was contrary to the behaviour of healthy volunteers, showing neither a norepinephrine overflow nor increased heart rate. In patients with atrial fibrillation, AV-conduction also increased with elevated norepinephrine levels in plasma. There was, however, no direct correlation. Determination of the cardiac AV-difference of plasma-norepinephrine levels showed a cardiac catecholamine overflow, which could be inhibited by specific and nonspecific antiarrhythmic drugs (Verapamil, Practolol). In studies of catecholamine and glucocorticoid metabolism, no significant difference of catecholamine and VMA could be determined in patients with normal blood pressure and arterial hypertension. There was, however, a tendency to increased values in patients of the last group. In postural hypotension, plasma levels and urinary excretion of catecholamines were decreased and showed no variation after physical stress in orthostasis and after nicotine. In patients with tumors of the adrenal cortex and medulla, a close relation of the disturbance in catecholamine and corticoid metabolism was revealed.

[Hemodialysis in a child with accidental digitalis poisoning (author's transl)]

A case of an accidental digitalis intoxication in a two year old child is reported. Early Hemodialysis effectively reduced the high plasma levels of digoxin and replaced other therapeutical procedures.

[Treatment of bradycardia with an atropine ester]

In view of the unsatisfying drug treatment of bradycardias in most cases, clinical studies with new compounds seem to be urgent. A report is given on experiences with a derivative of atropine (gen. Ipratropiumpromid) in 34 cases suffering from various types of bradycardias. Comparing heart rate following intravenous injections of 0.5 to 1.0 mg, the new drug proved to be definitely more effective than atropine sulfate. Side effects were limited to diminution of salivary glands function.