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

摘要:

Electrocardiographic, enzymatic, and morphologic signs of myocardial ischemic injury following coronary occlusion have previously been shown to be ameliorated by reducing myocardial oxygen requirements, and/or by increasing the availability of oxygen as well as of substrates for anaerobic ATP production. Since hyaluronidase increases diffusion through the extracellular space and may facilitate delivery of substrates to ischemic cells, the influence of its administration on the size of experimentally produced infarcts was studied. In 14 control dogs epicardial electrocardiograms were taken in 10-15 sites on the anterior surface of the left ventricle before and after occlusion of the left anterior descending coronary artery. Twenty-four hours later, transmural specimens were obtained from the same sites from which electrocardiograms had been recorded, and were analyzed for creatine phophokinase (CPK) activity, for histologic changes, and glycogen content. In control dogs, sites exhibiting S-T-segment elevation 15 min after occlusion showed early structural signs of necrosis and glycogen depletion in 97% of specimens taken after 24 hours. The relationship between S-T-segment elevation at 15 min (mv) and CPK activity 24 hours later (IU/mg protein) was log CPK = −0.061 S-T + 1.26. Hyaluronidase (225 u/kg) was given to 15 dogs; no hemodynamic changes occurred but the depression of CPK activity was reduced following occlusion; log CPK = −0.024 S-T + 1.28. Similarly, only 55% of sites that showed S-T-segment elevation prior to hyaluronidase administration exhibited histologic signs of early infarcts and glycogen depletion 24 hours later. It is concluded that hyaluronidase diminished myocardial necrosis following acute coronary occlusion.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Myocardial blood flow responses to selective coronary arteriography were studied in 22 patients. Left coronary flow was estimated by the radioactive inert-gas (133xenon) washout technic using precordial detection. Duplicate control studies were obtained before radiocontrast injection and test studies were performed at 1 min and 3, 5, or 7 min after angiography. Eleven patients received a single 7-ml injection of methylglucamine diatrizoate and 11 were given a series of injections (average total 40 ml), with the test blood flow studies after the final injection.Myocardial flow increased in every patient 1 min after contrast injection (average control flow 66.3 ml/min/100 g; test flow 78.8, +18.9%,P< 0.001). Blood flow increased further in seven of 10 studied at 3 min (average 95.7 ml/min/100 g, +35.7%,P< 0.001) and remained elevated at 5 and 7 min. Systemic pressure was unchanged from the control level, so coronary vascular resistance decreased in proportion to the increase in flow. Blood flow responses in patients with coronary artery disease were no different from normal subjects. Sham injections of normal saline produced no increase in coronary flow.Selective coronary arteriography results in a prompt increase in myocardial blood flow which persists for several minutes. The probable mechanism is coronary vasodilatation produced by the markedly hypertonic contrast material, an effect demonstrated previously in other vascular beds.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

By the use of the xenon-residue detection technic, myocardial blood flow (MBF) was assessed 3-17 months after surgery in nine patients with an aorta-to-left anterior descending bypass (LAD-BP), in nine patients with an aorta-to-right coronary artery bypass (RCA-BP), and in two patients with both LAD-and RCA-BP. In addition, MBF was registered in the corresponding main coronary artery. In each case coronary angiography revealed a patent vein graft. LAD-BP flow averaged 58 ml/min/100 g, this being slightly lower than the average flow value recorded after injection into the main left coronary artery of these patients (64 ml/min/100 g). LAD-BP flow did not differ from the value recorded in 20 normal subjects (63.9 ml/min/100 g). In contrast, average RCA-BP flow amounted to 47.1 ml/min/100 g and was significantly higher than the values recorded in the obstructed main RCA of these patients (22.1 ml/min/100 g) (P< 0.0025) or those observed in 20 patients with severe disease of the right coronary artery (34.9 ml/min/100 g) (P< 0.025); no difference was seen between RCA-BP flow and the average of 20 normal subjects (46.1 ml/min/100 g). In six patients a two-to threefold increase of BP flow was found during exercise (50-100 w). Total coronary vascular resistance showed a similar behavior to MBF, not differing in the bypass area from the values obtained in the normal control groups. It is concluded that the venous bypass procedure substantially increases perfusion at rest and during exercise and that a good correlation exists between MBF and postoperative angiography.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

This study was undertaken to define the hemodynamic changes in hypertension of chronic end-stage renal disease. Mean cardiac index in 75 uremic patients was higher (P< 0.001) than that of 42 normal volunteers while stroke index was not different from normals. The higher cardiac indices of uremic patients were accounted for by increased heart rates. Despite the significantly higher blood pressure in the uremics, their mean total peripheral resistance index was not different from that of normals.The total group of 75 patients included 52 hypertensive and 23 normotensive uremics. Cardiac index, heart rate, and stroke index were the same in 52 hypertensive and 23 normotensive uremics while mean total peripheral resistance index of hypertensive uremics was higher (P< 0.001) than normotensive uremics. Therefore, the hypertension in end-stage renal disease is sustained by a high total peripheral resistance.Bilateral nephrectomy in 12 hypertensive uremics resulted in no changes in cardiac index; a consistent decrease in blood pressure (P< 0.001) and a decrease in total peripheral resistance index (P< 0.001) occurred. Bilateral nephrectomy in eight additional uremics with malignant hypertension resulted in an actual increase in cardiac index (P< 0.001) with a consistent reduction in blood pressures (P< 0.001) and an even more dramatic decrease in total peripheral resistance (P< 0.001).These findings imply that a vasopressor substance of renal origin increasing peripheral resistance is the major factor in the pathophysiology of renal hypertension in the late stage of its natural history.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The AVCO balloon pump has been employed in treating 40 patients with cardiogenic shock from acute myocardial infarction (CS-MI). All patients were given a trial of medical therapy with hemodynamic monitoring. The time from the development of shock to institution of intraaortic balloon pumping (IABP) was less than 24 hours in all but nine patients. Prior to IABP the mean hemodynamic values were: cardiac index (CI) 1.7 liters/min/m2; mean arterial pressure (MAP) 66 mm Hg; pulmonary artery wedge pressure (PAW) 22 mm Hg. After 24-48 hours of IABP the CI and MAP had increased 0.8 liters/min/m2and 8 mm Hg, respectively, and the PAW had decreased 4.8 mm Hg. During IABP the shock syndrome was reversed in 31 patients. Four of 25 patients treated with IABP alone survived to be discharged, but two have died from subsequent infarctions. Because of the persistent high mortality, 15 patients judged unable to survive off IABP have undergone emergency surgical procedures with IABP continuing during preoperative angiography and postoperatively. Six were long-term survivors. It is concluded: (1) IABP is a safe, effective means of supporting the circulation in CS-MI; (2) IABP alone will improve survival in some patients; (3) IABP can provide circulatory support during angiography and the perioperative period in patients requiring revascularization for survival; and (4) some patients with CS-MI have myocardial necrosis too extensive to permit survival without permanent circulatory assistance or total cardiac replacement.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Left heart volume and left ventricular mass (LV mass) were calculated from biplane cineangiocardiograms in 58 tetralogy of Fallot (TF) patients preoperatively, in 31 patients after shunt procedure, and in 24 patients after complete correction. Preoperatively, the LV end-diastolic volume and left atrial maximal volume (LAmax) were normal in cyanotic infants less than 2.0 years old and in acyanotic patients more than 2.0 years old. These variables, however, were less than normal in cyanotic children > 2.0 years old. Left ventricular ejection fraction (LVEF) and LV systolic index (LVSI) were both less than normal in all groups preoperatively. LV mass was normal preoperatively. After successful shunt procedure, there was a significant increase (P< 0.01) in LVEDV, LVSI, LAmax, and LV mass. The LVEF, however, remained less than normal. After successful corrective surgery, the total group showed a significant increase (P< 0.01) in LVEDV, LVSI, LAmax,and LV mass as compared with preoperative values. Furthermore, the LVEDV was slightly but significantly higher than normal and the LV ejection fraction remained significantly depressed from normal. There was an inverse correlation between LVEDV or LVSI, expressed as a percent of normal, and hemoglobin concentration but not with the net left-to-right shunt or aortic saturation.The decreased LV ejection fraction in cyanotic tetralogy patients in the presence of decreased peak LV pressure (decreased afterload) as well as the decreased LVEF after shunt procedure or complete correction (increased preload) suggests that LV function is depressed in tetralogy patients and remains depressed despite corrective surgery.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

A patient with acute severe mitral regurgitation resulting from papillary muscle dysfunction which developed on the third day of acute myocardial infarction underwent early successful mitral valve prosthetic replacement with concomitant aortocoronary saphenous vein bypass. The concept of acute severe mitral regurgitation due to an infarcted papillary muscle which has not actually ruptured and an aggressive approach to such a catastrophic event early in the course of acute myocardial infarction are emphasized. The risk is well worth the gratifying result obtained in our patient who successfully underwent such a combined operative procedure for one of the early complications of acute myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The importance of two arrhythmogenic mechanisms, ventricular reentry and automaticity, was assessed after coronary ligation in 35 cats. Automaticity was estimated by the frequency of ventricular escape beats after intravenous acetylcholine, and reentry was estimated by the number of repetitive beats induced by premature ventricular stimuli. Increased automaticity only was present after coronary ligation in two studies; increased reentry only was noted in 24; and both increased automaticity and reentry were seen in nine studies. Incremental doses of lidocaine (2-4 mg/kg), propranolol (0.1-0.3 mg/kg), or procainamide (5-15 mg/kg) consistently returned automaticity to normal. Procainamide abolished repetitive beats in 12 of 13 studies, propranolol did so in eight of 11, but lidocaine did so in only six of 17. Repetitive beats actually increased in six studies after lidocaine, at a time when lidocaine blood levels were in the lower therapeutic range. A persistent arrhythmia appeared after coronary ligation in 12 studies; in 10 the disappearance or persistence of the arrhythmia after drug administration matched the disappearance or persistence of repetitive beats. We conclude that both reentry and increased ventricular automaticity appear during myocardial infarction but that reentry seems of greater importance in the genesis of arrhythmias. These drugs are more reliable in normalizing automaticity than in abolishing reentry; the failure of a drug may thus be related to its failure to abolish reentry. Moreover, lidocaine may accentuate ventricular reentry, especially at the lower blood levels.

ISSN:0009-7322    

出版商:OVID    

年代:1972

数据来源: OVID