ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Precordial electrocardiographic mapping has been proposed as a method for evaluating the extent of myocardial injury in patients with acute myocardial infarction. To assess the relationship between direct measures of myocardial cell damage and findings obtained by precordial mapping, the left anterior descending coronary artery (LAD) was occluded in dogs instrumented for simultaneous recording of epicardial and precordial electrocardiograms. The sum in millivolts of ST-segment elevation recorded from 30 electrodes placed in a Silastic grid sutured to the epicardium (Epi∑ST) was compared to that recorded from 30 precordial electrodes (Pre∑ST). While ischemic injury was: 1) maintained constant with a fixed occlusion; 2) reduced by partial reperfusion; 3) increased by addition of a second occlusion; or 4) increased repeatedly by intermittent infusions of isoproterenol, Epi∑ST and Pre∑ST were always closely correlated in each of the 16 dogs studied:r= 0.92 ± 0.01 (sem). In seven control dogs, 30 minutes after coronary occlusion, Pre∑ST had fallen to 77.4 ± 6.6% of its value 15 minutes postocclusion. In seven experimental dogs, two branches of the LAD were occluded. Fifteen minutes after double occlusion, one occlusion was released; 30 min after the initial occlusion Pre∑ST had fallen significantly more than control, to 43.1 ± 13.1% of its value 15 minutes postocclusion. Simultaneously, epicardial sites in the reperfused area also showed normalization of ST segments and 24 hours later exhibited normal myocardial creatine phosphokinase activity and normal histologic appearance. During the same experiment, the mean precordial R wave voltage of sites with ST-segment elevations exceeding 0.15 mV 15 minutes following occlusion fell significantly (P< 0.05) more in the control group (from 1.14 ± 0.15 to 0.75 ± 0.06 mV) than in the reperfused group (from 1.06 ± 0.09 to 0.96 ± 0.17 mV) during the ensuing 45 minutes. Thus, more rapid normalization of Pre∑ST or preservation of precordial R wave voltage reflected the actual prevention of myocardial necrosis by reperfusion. These findings demonstrate the usefulness of precordial electrocardiographic mapping for evaluating changes in myocardial ischemic injury. Sites at which appearance of epicardial ST segment is not a reliable index of ischemic injury were associated with the development of intraventricular conduction blocks with Q to intrinsic deflection intervals exceeding 40 msec or QRS durations exceeding 65 msec; these changes were associated with precordial RSR′ configurations. Such sites, whether recorded from precordial or epicardial leads, should be excluded from ST-segment measurements used in the assessment of myocardial ischemia.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Serious obstructive coronary artery disease was found in all patients who developed hypotension accompanying the onset of angina during multistage exercise testing. Seventeen exercising patients demonstrated a fall in systolic pressure to below resting levels as chest pain and ST-segment depression appeared. Two patients died suddenly six weeks after treadmill testing and prior to arteriography. The remaining fifteen were studied with coronary arteriography and all except one exhibited ≥ 90% stenosis of the left anterior descending artery (LAD). The remaining patient demonstrated two 75% LAD stenoses in series. Five exhibited significant (≥ 75%) narrowing of the main left coronary artery (MLCA) and thirteen of fifteen had significant stenosis of proximal LAD and circumflex arteries. The two patients without significant circumflex disease exhibited ≥ 90% stenosis of the dominant right coronary artery (RCA) circulation. Six of six patients had restoration of a normal blood pressure response following coronary bypass surgery, which also relieved angina and reversed ST-segment depression.Conditions essential for proper interpretation of this sign are discussed. If these conditions are met, then a fall in systolic pressure during treadmill-induced angina pectoris is a reliable sign of severe compromise of left ventricular blood supply.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Thirty-five patients with typical Prinzmetal's variant angina were studied by coronary cineangiography. There was no demonstrable stenosis of the major coronary arteries in 19 patients. Nine patients with single coronary stenosis underwent aortocoronary bypass and had recurrence of the symptoms postoperatively.Administration of nifedipine effected complete cessation of the symptoms among patients formerly treated medically. Although surgical treatment did not effect permanent relief of pain, all patients initially treated surgically experienced relief of pain when nifedipine was administered.The pathophysiology of variant angina remains obscure. Our results suggest that neurohumoral factors exert more of an effect on the myocardial cell than on the coronary vessels.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Myocardial blood flow in 16 patients before and after coronary bypass surgery in conjunction with coronary angiography, left ventricular function measurement, and graded exercise test. Radioactive133Xe was injected into the coronary artery or bypass graft and the washout was recorded by an Anger camera. Myocardial blood flow increased in 11 out of 14 patients and decreased in three patients. The average flow was 55 (±6) preoperatively and 96 (±10) ml 100 g/min postoperatively. Increase of blood flow occurred in both the bypassed left anterior descending coronary artery (LAD) region and the nonbypassed left circumflex coronary artery (LCIR) region. The postoperative flow increase and the absolute postoperative flow values are higher with saphenous vein than with mammary artery grafts. Statistically significant correlation is not found between myocardial blood flow changes and exercise tolerance. The volume measurements (end diastolic volume, stroke volume, ejection fraction) remained unchanged.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Symptomatic, nonsyphilitic, acquired coronary ostial stenosis is a rare angiographic finding and was found in 0.13% of 3000 coronary angiograms. Three females with this lesion have been treated surgically. Two had left coronary ostial involvement. Coronary angiography may result in catheter tip occlusion of the ostium with chest pain, dyspnea, diaphoresis, systemic hypotension and abrupt fall in pressure at the catheter tip. Recognition of this entity is necessary for safe coronary angiography. Involvement of the left ostium carries the same serious prognosis as does left main coronary disease.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

The effects of infusions of glucose, insulin and potassium (GIK) on the heart tissue metabolic changes found in adult baboons 60 min after coronary artery ligation were studied. Biopsies taken from 11 baboons without coronary artery ligation gave control values. A second group of 46 baboons had coronary artery ligation. A third group of 17 baboons received an infusion of KCl after coronary artery ligation. A fourth group of 26 baboons received infusions of GIK. Coronary artery ligation resulted in the expected fall of ATP, creatine phosphate, glycogen, tissue (K+/Na+) ratio, and tissue pH, and rise of inorganic phosphate, lactare, lactate/pyruvate ratio and &agr;-glycerophosphate in the infarction zones. Compared with ligation, additional infusions of GIK approximately doubled the contents of creatine phosphate and glycogen in the infarct zones, increased the content of ATP in the central infarct zone, and decreased the content of inorganic phosphate in the peripheral infarct zone. Other GIK effects were that the tissue (K+/Na+) ratio rose in the peripheral infarct zone, and the content of both glycogen and lactate rose in the peri-infarct and non-ischemic zones; the pH of tissue homogenates did not decrease. KCl infusions had few effects compared with the ligation group. GIK infusions exerted a beneficial effect when compared with infusions of KCl in that tissue creatine phosphate rose in the peripheral infarct and nonischemic zones; the tissue K+/Na+ratio rose in the peripheral infarct, peri-infarct, and nonischemic zones; and the lactate/pyruvate ratio fell in the infarct zone. It is proposed that GIK counteracted early tissue metabolic deterioration in the infarcting baboon heart.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

To study the pathway of tachycardia in patients with the Wolff-Parkinson-White (WPW) syndrome and reciprocal tachycardias, results from intracavitary recordings and atrial and ventricular stimulation were reviewed in 71 patients with the WPW syndrome and 54 patients without pre-excitation. In all patients a reproducible tachycardia could be initiated and terminated by appropriately timed electrical stimuli. The following findings were accepted as suggesting the participation of an accessory pathway in the tachycardia circuit: 1) no increase in ventriculo-atrial conduction (V-A C) time following ventricular stimuli given with increasing prematurity; 2) activation of right or left atrium (depending upon the location of the atrial end of the accessory pathway) prior to activation of atrium in the His bundle lead; 3) slowing of tachycardia following bundle branch block to the ventricle in which the accessory pathway inserts; 4) V-A C time of early stimuli on the ventricle during tachycardia equal to or less than the V-A C time following QRS complexes during tachycardia; 5) inability to initiate tachycardia or slowing of tachycardia following the administration of drugs affecting the accessory pathway. Accepted as suggestive for atrioventricular (A-V) nodal re-entry were the following factors: 1) activation of atrium following initiation of tachycardia by a single atrial premature beat after activation of the bundle of His but before or simultaneous with ventricular activation in first and subsequent beats of tachycardia; 2) initiation of tachycardia following a gradual increase in V-A C time with the appearance of a His bundle electrogram in between the premature beat and retrograde atrial activation; 3) gradual increase in V-A C time with the appearance of a His bundle electrogram following ventricular premature beats given with increasing prematurity; 4) two-to-one block distal to the A-V node or His bundle with persistence of tachycardia.If only positive findings were accepted, 51 patients of the WPW group used their accessory pathway during tachycardia. In eight patients re-entry was confined to the A-V node. In the remaining 12 patients the mechanism was not clear. Of the patients not showing pre-excitation in A-V direction, 47 patients seemed to have their re-entry circuit in the A-V node, five patients used an accessory pathway in V-A direction, and in two patients the pathway of tachycardia could not be identified.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Resting ECGs, exercise treadmill tests and 24-hour ambulatory ECGs were recorded and analyzed in 24 unselected patients with mitral valve prolapse. Arrhythmias were frequent. There were three distinct groups of patients, defined on the basis of total number of premature ventricular contractions (PVCs) during the 24 hours: there were no PVCs in 25%, infrequent PVCs in 25%, and frequent PVCs in 50%. Complex ventricular arrhythmias, including ventricular tachycardia in five patients, were found almost exclusively in the group with frequent PVCs. Fifteen of the 24 patients demonstrated atrial premature contractions (APCs) during the 24 hours. Complex atrial arrhythmias were found among patients with infrequent, as well as those with frequent, APCs. Supraventricular tachycardia was detected in seven of these patients. The incidence of PVCs decreased during sleep in 58% of the patients, increased in 17%, and showed no change in 25%. The incidence of APCs decreased during sleep in 67% of the patients and showed no change during sleep in 33%. A poor correlation was found between symptoms recorded in patient diaries and changes noted on 24-hour ECG recordings. The peak PVCs/15 min and peak APCs/15 min during a 24-hour period of monitoring was found to be an excellent guide to the total number of PVCs and APCs occurring during that period. This permits an accurate prediction of the total number of PVCs in 24 hours after performing an exact PVC count on only 15 minutes of ECG data. Finally, the 24-hour ambulatory ECG was more sensitive than the treadmill test and both were superior to the 12-lead ECG for detecting arrhythmias in these patients.

ISSN:0009-7322    

出版商:OVID    

年代:1975

数据来源: OVID