摘要:

Ectopic atrial, A-V junctional, and ventricular tachycardias in man have been associated with digitalis medication. Recently it has become possible to distinguish various locations of pacemakers within the specialized conduction system of the ventricles on the basis of the form of the QRS complexes in the standard electrocardiogram. Tachycardias originating in the left bundle branch and documented by right, left, and His bundle recordings have been produced in animals given excessive digitalis. We have noted a similar tachycardia in a patient with ischemic heart disease receiving digitalis during hypokalemia. The QRS complexes were 0.10 sec in duration and by contour suggested an ectopic focus located in the posterior fascicle of the left bundle; His bundle recordings were consistent with this diagnosis. As the ectopic rhythm became synchronized with a slightly irregular sinus rhythm, bidirectional depolarization of the His bundle with fusion His potentials could be demonstrated.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Myocardial lactate extraction, arterial-coronary sinus difference (A-CS) of potassium (K+), hemodynamics, and S-T segments were studied in 15 patients with coronary artery disease who developed angina during atrial pacing. The study consisted of the following periods: control (C1), pacing (P1), recovery (C2), control after nitroglycerin (CGTN), second pacing (P2), and recovery. During C1, mean lactate extraction, S-T segments, and left ventricular end-diastolic pressure (LVEDP) were normal, and there was no myocardial K+loss. During P1the mean lactate production was −12.0%, mean K+loss −0.26 mEq/liter, and mean S-T segment depression 1.97 mm, while the average LVEDP remained unchanged, increasing when pacing was discontinued to a mean value of 23.3 mm Hg. These values returned to control levels by the time GTN was administered. After GTN there were significant decreases in mean cardiac index, LVEDP, brachial artery pressure, and left ventricular stroke work. During P2, eight subjects had no pain, five experienced less severe angina, mean lactate production and K+loss were abolished, S-T segments became less depressed (0.8 mm), and mean LVEDP decreased during pacing, rising only to 11.4 mm Hg when pacing was discontinued. Myocardial lactate production reverted to extraction in two patients and decreased in another two, whereas seven patients showed a decreased K+loss or uptake. It is concluded that GTN may prevent or reduce pacing-induced angina, as well as improve the electrocardiogram and hemodynamics, and in some patients decrease myocardial anaerobiosis.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Day-to-day variation of the corrected orthogonal electrocardiogram was investigated in 20 normal subjects. Ten recordings were made in each individual with chest electrode positions left unmarked first, after which 10 subjects underwent another series of 10 consecutive daily recordings with marked electrode locations. Mean and maximal day-to-day variations of durations and amplitudes of different deflections of scalar leads as well as variations of directions and magnitudes of several QRS and T spatial vectors have been studied using computer technics for measurement and analysis.Repeat variability in the unmarked recordings was relatively large. For example, the maximum (96%) variability in QRS spatial maximum and in R-wave amplitudes in leads X and Z were, respectively, 0.50, 0.61, and 0.35 mv. Marking of the chest did reduce variability of amplitude and angular measurements by approximately 25%, but even then a substantial variation from day-to-day remained. Relative changes in T-wave amplitude and direction were greater than those of the QRS complex.The results presented can be used as standards to assess ECG changes observed in serial electrocardiography.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Appropriate surgical and medical management of the patient with ischemic heart disease depends upon a thorough assessment of the clinical and pathophysiologic derangements in left ventricular function. This study examined the spectrum of abnormalities in ventricular function found in 66 patients with documented coronary artery lesions.Catheterization and biplane angiocardiography were used to measure end-diastolic and end-systolic volume (EDV, ESV), systolic ejection fraction (SEF), ventricular mass (LVM), end-diastolic pressure (LVEDP), peak systolic and end-diastolic stress (PSS, EDS), and stroke work (SW). The pattern of ventricular contraction was assessed for hypokinesis, akinesis, and dyskinesis and graded according to severity.The SEF, SW, and contractile pattern were sensitive and interrelated indicators of left ventricular contractile dysfunction or fiber shortening. Measurements of ventricular filling or fiber lengthening (EDV, LVEDP, EDS) were related but less sensitive parameters of dysfunction. However, when contractile function was reduced to about one half of normal, there was an associated marked increase in EDV, EDS, and LVEDP.A wide spectrum of derangements was found ranging from virtually normal function in 18 patients with angina alone to severe dysfunction in 18 patients with myocardial infarction, mitral regurgitation, or heart failure.Abnormalities in ventricular function were uniformly associated with myocardial infarction. Angina alone was associated with minimal or no ventricular dysfunction. Most patients with mitral regurgitation and all patients with heart failure had severe ventricular dysfunction manifested by an increase in EDV, LVM, and PSS, a marked decrease in SEF and SW, and a severe abnormality in contractile pattern.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Electrophysiologic events in a 52-year-old man with Wolff-Parkinson-White (W-P-W) syndrome, type B, recurrent supraventricular tachycardias, and coronary artery disease were studied during cardiac catheterization and at open-heart surgery.During cardiac catheterization reciprocal tachycardias were repeatedly initiated by premature atrial beats and terminated by rapid right atrial pacing. Our results confirm that the tachycardia usually seen in the W-P-W syndrome is reciprocal tachycardias with orthograde conduction to the ventricles through the normal atrioventricular conduction system and retrograde conduction to the atria via the Kent bundle.The epicardial surface of the ventricles was “mapped’ at surgery. The earliest site of excitation was the posterior base of the left ventricle near the crux of the heart. Kent bundle conduction was temporarily ablated with lidocaine (Xylocaine) hydrochloride.This is the first case of W-P-W syndrome, type B, in which the anomalous A-V bundle entered the left ventricle. Our results indicate that the analysis of the electrocardiogram in localizing an abnormal A-V connection cannot be relied upon completely.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Cerebral blood flow (CBF) was measured during 28 carotid endarterectomies in 25 patients, by injection of133Xe into the exposed internal carotid artery (ICA). Twenty-three patients had episodic cerebral or retinal ischemia and five had neurologic deficits before operation. Initial CBF values were variable. Increases of PaCo2caused CBF to increase in four of six patients, to increase slightly in one, and to decrease in one. In each of 19 procedures, CBF decreased during surgical occlusion of the ICA, 11 times to less than 30 ml/100 g/min, but absence of postoperative worsening indicated that decreased ICA blood flow is not a major risk of the procedure; embolization from the site of operation may be a greater threat to the patient. CBF increased after 14 endarterectomies, perhaps due to failure of autoregulation or to reactive hyperemia. Measurements of jugular PVo2and lactate concentration were of little value.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Despite the recent accumulation of a large hemodynamic data base describing myocardial infarction and cardiogenic shock, precise characterization of patient subsets has been elusive. This paper represents an attempt to identify the major factors contributing to this wide hemodynamic spectrum, and their interrelation using a theoretical model based upon currently emerging concepts of this disease. It is proposed that the hemodynamic alterations associated with acute infarction are a consequence both of reduction in contractile mass and alteration in left ventricular compliance. In addition, mitral insufficiency, altered contractility, and the peripheral circulation interact to produce wide divergence between clinical and hemodynamic features from case to case and during the progression of the course of the illness. This model may more rationally explain the genesis and natural history of “heart failure’ and the “shock syndrome’ associated with acute myocardial infarction and in addition explain the extremely variable responses to both drug therapy and to more aggressive modes of treatment of power failure.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

As a plan of therapy for shock associated with acute myocardial infarction in a general hospital and assuming that septic and hemorrhagic shock has been eliminated as diagnostic possibilities we would suggest the following:(1) Pain should be relieved using morphine or pentazocine, and atropine if brady-cardia is present. Oxygen by mask should be administered to bring the arterial oxygen tension to about 100 mm Hg. The airway must be examined and, if air exchange is poor and the arterial oxygen very low or carbon dioxide high, respiratory assistance and occasionally intubation may be required.(2) Blood pressure must be stabilized at an adequate level for perfusion of vital organs, or progression may be so rapid that death will occur before proper evaluation can be made and more rational therapy started. For this purpose we would start a norepinephrine infusion at a rate just sufficient to keep the systolic blood pressure near 100 mm Hg. If the shock syndrome is present but arterial pressure is normal or only slightly reduced, we would eliminate this step in therapy.(3) Arrhythmias or heart block should be corrected by methods discussed elsewhere in this symposium.(4) A venous catheter should be inserted so that the catheter tip is just within the thorax. If the central venous pressure (CVP) is below 10 cm H2O we would begin a regimen of plasma volume expansion giving 100 cc of40dextran over a period of 10 min, waiting 10 min, and if the CVP has not risen 1 cm H2O repeat the process until shock is relieved, the CVP continues to increase or is above 15 cm H2O, or 1000 cc of40dextran has been given. If the patient accepts more than 1000 cc of fluid in this manner without elevating the CVP it is most likely that some other major process causing fluid loss is complicating the myocardial infarction.(5) If or when CVP is above 10 cm H2O, and if the patient remains in shock and is hypotensive, we would add norepinephrine infusion at a rate just sufficient to bring the systolic pressure between 100 and 110 mm Hg. If this cannot be accomplished with small amounts of norepinephrine then intraarterial pressure must be measured since the discrepancy between the cuff pressure and actual pressure may be increasing with further pressor infusion.(6) If the patient is normotensive and has a CVP above 10 cm H2O but manifests the shock syndrome, an isoproterenol infusion should be instituted, but to use this regimen one must be able to measure intraarterial pressure. If CVP falls, simultaneous plasma volume expansion may be necessary. If arterial pressure begins to fall, norepinephrine should be substituted. We would use dopamine first in this particular situation, but this agent is not as yet generally available.(7) With the CVP elevated and blood pressure stable, arterial oxygenation established, and arrhythmias corrected, if the patient is still in a low cardiac output state with continued oliguria and poor tissue perfusion, digitalization with about half to two thirds the normal digitalizing dose should be undertaken.(8) If a further inotropic response is needed glucagon may be added at this point. With an initial bolus injection efficacy should be established and if found helpful a constant infusion should follow. Aminophylline should be given simultaneously to potentiate the action of glucagon.(9) The patient who at this point remains oliguric and with a small pulse pressure may be benefited by cautious vasodilation with chlorpromazine or phentolamine and simultaneous further plasma volume expansion.(10) A patient who remains pressor-dependent or responds poorly to pressors will probably need circulatory assistance. However, unless some definitive measure can be undertaken to restore or replace nonfunctioning myocardium this too will be of little benefit.(11) A patient who stabilizes well but experiences a fall in blood pressure as the pressor infusion is being discontinued should have plasma volume expansion as the pressor infusion is decreased. The physician must resist the temptation to restart the infusion as the pressure falls, unless the shock syndrome accompanies the hypotension.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Congestive heart failure (CHF) occurs in about one half of all patients with acute myocardial infarction and is a manifestation of acute alterations in left ventricular function. In the present study CHF is defined on clinical grounds, according to the presence and extent of bilateral pulmonary rales. An accompanying S3ventricular gallop was heard in 58% of our patients with heart failure initially, but it disappeared eventually in the majority. Dilatation of pulmonary veins and blurring of pulmonary vascular markings are useful roentgenographic signs which reflect elevations in left heart filling pressure. At times the earliest indicators of heart failure, these findings appear in general to be less sensitive than the physical examination in diagnosing CHF. Although stroke volume is decreased with CHF, cardiac index is generally maintained by increased heart rate. Left ventricular minute work and stroke work are significantly decreased, while left ventricular end-diastolic pressure is significantly increased, in patients with CHF complicating acute myocardial infarction. Arterial hypoxemia is common and the degree of arteriovenous shunting is roughly proportional to the elevation of left ventricular filling pressure. The mortality of patients with CHF is approximately three times that of patients with acute myocardial infarction and no complications. Diuretic therapy is safe and effective. Attention is called to the probability that the use of digitalis preparations in the early hours following myocardial infarction is hazardous. Furthermore, hemodynamic benefit from digitalization in the early postinfarction period remains unproven.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID