Influences of the adrenergic nervous system on the repolarization phase of the electrocardiogram

The following conclusions can be drawn : (1) The nervous outflow to the heart may be varied from the baseline to opposite directions by different stressful stimuli. (2) ST-T alterations may be induced and abolished by adrenergic activation and inhibition respectively. (3) These effects are dissociated from or not necessarily associated with an exaggerated responsiveness of the cardiac beta receptors. (4) The adrenergic influences on the ST-T abnormalities of myocardial ischemia and hypertension are limited.

Pulmonary hemodynamics and right ventricular function in hypertension

Pulmonary and systemic hemodynamics in 16 hypertensive subjects (group I) with left ventricular (LV) hypertrophy (ECG and echo criteria) and in 17 hypertensive subjects with ECG signs of LV strain (group II), were compared with those in 14 normal individuals. An augmented pulmonary arteriolar resistance (PAR) in group I and to a larger extent in group II accounted for the pulmonary pressure elevation in both groups. Increase in PAR was unrelated to pulmonary blood flow and volume, pleural pressure, arterial PO2, PCO2 and pH, and could not be explained entirely by the left ventricular end-diastolic pressure changes. In group I, left (L.MSEJR) and right (R;MSEJR) mean systolic ejection rate, stroke index (SI) and mean velocity of circumferential fiber shortening (VCF) were enhanced in spite of the heightened pressure load on both sides of the heart. In group II, a large reduction of SI, L.MS.EJR, R.MSEJR and VCF, as well as the relationship between ventricular filling pressures and SI, documented a compromised performance of both ventricles, Findings indicate that: systemic hypertension is associated with elevation of pulmonary arterial pressure and of PAR which is not necessarily a consequence of impairment in LV function; LV hypertrophy is associated with enhanced performance of either ventricle; in coincidence with development of ECG signs of LV strain, the performance of both sides of the heart deteriorates. A functional interdependence of the two ventricles is suggested.

Nifedipine, a new antihypertensive with rapid action

Oral (17 cases) or sublingual (9 cases) administration of nifedipine (10 mg), a new coronary dilator, induced a prompt and large pressure reduction in patients with severe primary hypertension. Pressure started to fall within 20 and 5 min after oral and sublingual administration, respectively, and reached the lowest levels in the next 10 min. Maximal mean arterial pressure reduction averaged 36 mm Hg; 120 min after the drug, mean arterial pressure was diminished by 19.5% of control. The hypotension was mediated through diminished peripheral resistance associated with rise of cardiac output and pulse rate. Nifedipine was also administered siblingually in 3 cases with hypertensive encephalopathy and acute left ventricular failure with average systemic and pulmonary arterial pressures from 307/164 and 91/55 mm Hg, respectively, which fell to 237/115 and 68/35 mm Hg 15 min after 10 mg of the drug, and were further reduced to 176/89 and to 47/19 mm Hg by an additional 10 mg.

Cardiac performance and beta-adrenergic blockade in arterial hypertension

The purpose of the study was to evaluate the functional changes which may occur in the human hypertensive heart following treatment with beta-blocking agents. In 54 primary hypertensive men investigated in the control state and after three weeks of treatment with propranolol (320 mg/day) it was seen that: (a) beta-adrenergic blockade depresses the pre-ejection, and probably the ejection left ventricular function; (b) the former effect is unrelated to changes in peripheral circulation, while the latter result may be either potentiated or overcome, depending on the direction to which treatment shifts the vascular resistance; (c) variations of impedance, rather than of blood pressure, influence the ejection left ventricular function; and (d) withdrawal of the adrenergic support to the heart, due to beta-blockade, is probably the primary factor responsible for the abnormal ventricular adaptation to an augmented impedance.

Cardiac function in the treatment of arterial hypertension with propranolol

1. Propranolol, when used for treating arterial hypertension, may influence determinants of both cardiac and vascular function; the consequent changes in cardiac performance may result from the interaction of different and possibly opposite effects. 2. Cardiac funtion was investigated in fifty-four primary hypertensive men in the pretreatment state and after 3 weeks of propranolol therapy at a daily dose of 320 mg. 3. beta-Receptor blockade caused depression of pre-injection left ventricular function, which was unrelated to the direction and the extent of changes in peripheral circulation. 4. The ejection left ventricular function could be either depressed or improved depending on the direction to which treatment shifted the vascular resistance, and consequently, the impedance to left ventricular ejection. 5. Withdrawal of the adrenergic support is probably the major factor responsible for the poor ventricular adaptation to an augmented impedance.

Antihypertensive action of propranolol in man: lack of evidence for a neural depressive effect

The hypothesis that a neural depressive action is related to the antihypertensive effects of beta blockers has been evaluated in 14 essential hypertensive male patients through the circulatory response to noxious stimuli. The pressor reaction to mental arithmetic was primarily mediated by cardiac stimulation (beta receptors activation), that to cold by vasoconstriction (alpha receptors activation). Arithmetic and cold were tested to separate the effects of peripheral beta blackade from possible neural and other influences. After propanolol (320 mg per day for 3 wk): (1) The baseline pressure was reduced; (2) appearance, peak, and disappearance time of the circulatory reaction to either stimulus was not altered; (3) the pressor effect of arithmetic was decreased in an extent proportional to the reduced rise of cardiac output; and (4) pressure during cold reached the pretreatment levels through an augmented increase of vascular resistance. Our findings indicate that propranolol depresses only the circulatory reactions mediated through beta receptors activation and provide no evidence of effects other than beta blockade.

Repetitive myocardial ischemia of Prinzmetal type without angina pectoris

In a patient with a normal electrocardiogram, normal treadmill exercise test, normal coronary arteriogram and no symptoms to suggest angina pectoris, continuous monitoring during several days exhibited repetitive (one to two per hour) S-T segment elevations in the precordial electrocardiographic leads and hemodynamic changes typical of Prinzmetal's angina (reduction in arterial pressure and cardiac index and increase in systemic peripheral resistance and pulmonary wedge pressure). This case demonstrates that electrical and dynamic cardiac alterations of Prinzmetal's angina can occur even in the absence of angina pectoris.

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

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

Long-term treatment of hyperkinetic heart syndrome with propranolol

Twelve men suffering from the primary hyperkinetic heart syndrome (PHHS) displayed palpitation, rapid and forceful heart action, increased pulsations of the large arteries, cardiac systolic murmur, and the following circulatory values (averages): systolic arterial pressure (SAP) =154 mm Hg; heart rate (HR)=91 b/min; cardiac index (Ci) =5494 ml/min/m2; left ventricular mean systolic ejection rate index (SMEJR) =227 ml/min/m2; left ventricular mean pre-ejection delta P/delta t (delta P/delta t) = 1.32 mm Hg/msec. A two-year followup during which propranolol was administered (80-160 mg/day) revealed good subjective improvement and disappearance of signs of circulatory hyperkinesis. At the end of this period the hemodynamic functions were as follows: SAP=134; HR=69; Cl=3489; MSEJR=171; delta P/delta t=0.89. Substitution of placebo for the active drug caused prompt reappearance of symptoms of cardiac overactivity in each patient, and brought the circulatory functions back to these levels: SAP=157; HR=96; Cl=5530; MSEJR=245; delta P/delta t=1.33. These findings lend further credence to the concept that the PHHS is, indeed, a definable disease entity; they also document that propranolol ameliorates the symptoms of the disease but is ineffective for the underlying disorder.

Negative influences of ascites on the cardiac function of cirrhotic patients

Right and left ventricular function was evaluated in 21 men with cirrhosis and tense ascites during staged removal of ascitic fluid. During paracentesis it was observed (1) that there was a significant increase in cardiac output, stroke volume, right and left ventricular stroke work and mean rate of systolic ejection; (2) that up to a certain stage of drainage (about 5,000 ml), there was a relationship between the amount of fluid removed and the intraabdominal and right atrial pressures and (3) that there was a direct relationship between improvement of cardiac function and normalization of right atrial pressure. It is believed that the increased intra-abdominal hydrostatic pressure acting upon the diaphragm affects the intrathoracic pressure to such an extent that the transmural filling pressure of the heart is reduced, and the mean pressure and respiratory pulsations of the right atrium increased, all of which impede venous return. Improved cardiac function during paracentesis appears to be due to an augmented filling of the heart and to a larger venous return.

Electrical and dynamic responses of the human hyperkinetic heart to sympathetic stimuli

1. The elevated beta-receptor responsiveness to adrenergic stimuli makes subjects with the primary hyperkinetic cardiac syndrome ideal for studying the electrical and dynamic responses of the heart to sympathetic activation. 2. In twelve men presenting with the syndrome, the effects of mental arithmetic and painful (cold) stress on the cardiac inotropic state were tested and correlated with the concomitant electrocardiographic changes. 3. Arithmetic and cold evoked responses opposite and divergent from the base-line state: the former induced vasodilatation, enhancement of cardiac rate, output, contractility and deep T wave inversion; the latter caused vasoconstriction, cardiac depression and full restoration of repolarization. 4. The sympathetic outflow elicited by stress is not generalized, but selectively directed to different circulatory levels in relation to the stimulus at work; cardiac sympathetic stimulation or inhibition has opposite effects on the repolarization phase.

Stress-induced and sympathetically-mediated electrocardiographic and circulatory variations in the primary hyperkinetic heart syndrome

As shown by the inotropic changes, the sympathetic discharge on the heart, is selectit syndrome. In the steady state the electrocardiogram shows flat, diphasic, or "tucked' T waves. Mental stimulation or isoproterenol, and, respectively, pain or beta blockade induce changes of the repolarization phase divergent from steady state. The former causes ST depression and deep T-wave inversion and the latter fully normalizes the repolarization phase. It is concluded that the electrical activity of the heart is directly influenced by the adrenergic drive in this disorder, and that different stressful factors can alter the repolarization phase in opposite ways in relation to the influence of the stimulus on the cardiac sympathetic tone.

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

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

Importance of the adrenergic nervous system in the support of cardiac function in patients with primary arterial hypertension

1. Because antiadrenergic therapy of hypertension may precipitate borderline cardiac compensation into failure, a method for detecting early cardiac insufficiency appeared desirable.

2. Eight out of thirty primary hypertensive patients were considered to be in incipient failure on the basis of the magnitude of the changes in left ventricular mean rates of systolic ejection and isovolumic pressure development after acute digitalization.

3. Antiadrenergic therapy precipitated these patients into overt failure, but did not affect cardiac performance in the others.

4. Left ventricular response to digitalis seems a reliable test in estimating cardiac reserve and in predicting the likelihood of decompensation after antiadrenergic treatment of hypertension.

Clinical, electrocardiographic, and haemodynamic effects of long-term use of propranolol in Prinzmetal's variant angina pectoris

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Left ventricular performance and related haemodynamic changes in Prinzmetal's variant angina pectoris

Attacks of Prinzmetal's variant form of angina pectoris are spontaneous, recur cyclically, and present unequivocal electrocardiographic alterations: they are ideal for a detailed haemodynamic study.Four patients with this form of angina were investigated. In each of them episodes occurred of electrocardiographic abnormalities either accompanied or unaccompanied by pain. During the same session, the cardiogram, heart rate, arterial pressure, and right atrial pressure were continuously recorded during periods ranging from 5 to 7 hours in each patient. Cardiac output was measured at selected times. Left ventricular ejection time, isovolumic contraction time, mean rate of isovolumic pressure development, and mean systolic ejection rate were also determined. In the 38 recorded anginal episodes, no circulatory change preceded the cardiographic modifications. From the onset of the electrocardiographic abnormalities to the beginning of their reversion, the following circulatory events were observed: (1) obvious reduction of cardiac output; (2) arterial hypotension; (3) lengthening of isovolumic contraction time and mean rate of isovolumic pressure development; (5) reduction of mean systolic ejection rate. It is concluded: (1) that no circulatory factor interfering with work or oxygen consumption of the heart is responsible for eliciting these anginal episodes; (2) that conspicuous left ventricular impairment occurs during the increasing and steady period of the electrocardiographic abnormalities. As the electrocardiogram started reverting to the pre-attack aspect, cardiac performance rapidly improved and, after a ;supernormal' phase, returned in about 2 minutes to basal levels. It is possible that this phase is dependent on a temporary sympathetic compensatory mechanism. No significant qualitative differences were detected between the circulatory pattern of various anginal episodes. The difference was mainly quantitative and the magnitude of the haemodynamic changes correlated well with the degree of the electrocardiographic abnormalities. Pain, when present, seemed just a concomitant symptom not significantly interfering with the circulatory changes associated with the episodes of this form of angina pectoris.

Continuous electrocardiographic recording in Prinzmetal's variant angina pectoris. A report of four cases

Four patients with Prinzmetal's variant angina pectoris were subjected to continuous electrocardiographic recording. In three of them several episodes of ST segment elevation unaccompanied by pain were recorded. In one patient, identical electrocardiographic alterations were observed both in presence or in absence of pain, while in the others a good correlation was evident between pain and severity of the electrocardiographic abnormalities. In two patients transmural myocardial infarction complicated the course of the angina. In contrast to the classical findings, in these patients the attacks of chest pain did not cease after the infarction, but became more frequent and severe. The electrocardiographic alterations of the anginal episodes occurred in the same myocardial areas involved by the infarction, so that a reversible superposition of electrocardiographic signs of acute ischaemia on those of recent necrosis was observed. Continuous electrocardiographic recording provided the best means of investigation of these patients with the variant form of angina pectoris.