Hemoglobin affinity for oxygen in the anginal syndrome with normal coronary arteriograms

Chest pain and angiographically normal coronary arteries. Implications for treatment

Approximately 20% to 30% of patients who undergo coronary arteriography for the evaluation of chest pain are found to have normal coronary arteries. These patients have a survival rate comparable to that of the normal population, yet they continue to complain of symptoms on extended follow-up, and about half of this group are disabled on account of chest pain. Once other clinically obvious disorders have been ruled out, common diagnostic considerations include microvascular angina, esophageal dysfunction, and perhaps fibromyalgia. Panic disorder, however, is the most common condition affecting these patients and can be diagnosed in at least one third of the group, with or without the presence of the other conditions mentioned. Appropriate diagnosis and treatment can reduce the psychosocial morbidity so frequently seen in these patients.

Abnormal coronary vasomotion during exercise in patients with normal coronary arteries and reduced coronary flow reserve

A reduced coronary flow reserve has been reported in patients with ischemialike symptoms and normal coronary arteries. In 13 such patients, both coronary vasomotion and flow reserve were studied. The luminal area of the proximal and distal third of the left anterior descending and left circumflex artery were determined by biplane quantitative coronary arteriography using a computer-assisted system. Patients were studied at rest, during submaximal supine bicycle exercise (4.0 minutes, 116 W), and 5 minutes after sublingual administration of 1.6 mg nitroglycerin. Heart rate, mean pulmonary pressure, and mean aortic pressure as well as the percent change of both proximal and distal luminal area were determined. In 10 of the 13 patients, coronary sinus blood flow was measured by coronary sinus thermodilution technique at rest and after dipyridamole infusion (0.5 mg/kg in 15 minutes) 10 +/- 5 days after quantitative coronary arteriography. Coronary flow ratio (dipyridamole/rest) and coronary resistance ratio (rest/dipyridamole) were determined in these patients. Patients were divided into two groups according to the behavior of the coronary vessels during exercise (vasodilation, group 1; vasoconstriction, group 2). Coronary vasodilation of the proximal (luminal area +26%, p less than 0.001) and distal (+45%, p less than 0.001) artery was observed in seven patients (group 1) during exercise and after sublingual nitroglycerin (+46%, p less than 0.001; and +99%, p less than 0.001, respectively). In group 2 (n = 6), however, there was coronary vasoconstriction of the distal vessel segments (-24%, p less than 0.001) during exercise, whereas the proximal coronary artery showed vasodilation (+26%, p less than 0.001) during exercise. After sublingual nitroglycerin, both vessel segments elicited vasodilation (distal coronary, +44%, p less than 0.001; proximal coronary artery, +47%, p less than 0.001). Coronary flow ratio amounted to 2.5 in group 1 and 1.2 in group 2 (p less than 0.05) and coronary resistance ratio to 2.7 in group 1 and to 1.2 in group 2 (p less than 0.05), respectively. Thus, among patients with ischemialike symptoms and normal coronary arteries, there is a group of patients (group 2) with an abnormal dilator response of the distal coronary arteries to the physiologic dilator stimulus of exercise and a reduced dilator capacity of the resistance vessels after dipyridamole (abnormal coronary vasodilator syndrome). The nature of this exercise-induced distal coronary vasoconstriction is not clear but might be due to an abnormal neurohumoral tone that may cause or contribute to the blunted vascular response during exercise.

Impaired coronary vasodilator responsiveness as a cause of lactate production during pacing-induced ischemia in patients with angina pectoris and normal coronary arteries

Subgroups of patients with angina pectoris and normal coronary arteries are known to have pacing-induced lactate production and, therefore, myocardial ischemia. To examine the mechanism of this pacing-induced ischemia, the effect of incremental atrial pacing on coronary blood flow and metabolism was studied in 27 patients with angina and normal coronary arteries. Seventeen patients continued to exhibit normal lactate extraction even at heart rates up to 160 beats/min (Group 1), whereas in 10 patients (Group 2) lactate extraction changed to production at the highest pacing rate. Coronary blood flow increased in Group 1 patients by 18, 41 and 75%, respectively, as heart rate was increased by 20 beat/min increments from 100 to 160 beats/min. In contrast, coronary blood flow increased by only 8, 7 and 14%, at the three respective pacing rates in Group 2. Between the heart rates of 100 and 160 beats/min, coronary vascular resistance decreased 32% in Group 1 patients but was unchanged in Group 2 patients. There was no significant change in the ratio of myocardial O2 consumption/rate-pressure product in Group 1 patients, but this ratio decreased from 0.91 +/- 0.26 ml O2 X min-1 X (mm Hg X beats/min)-1 to 0.53 +/- 0.11 (p less than 0.05) in Group 2 patients as heart rate increased from baseline to 160 beats/min. Thus, patients with angina and normal coronary arteries who develop ischemia with pacing have a decreased coronary vasodilator response that interferes with their ability to increase myocardial oxygen supply to match the higher demand.

Panic disorder: a frequent occurrence in patients with chest pain and normal coronary arteries

From 10% to 20% of patients undergoing coronary arteriography for chest pain are subsequently found to have normal coronary arteries. We investigated the prevalence of panic disorder in these patients in a two-stage study. Our results indicate that approximately one third of patients with chest pain and angiographically normal coronary arteries have panic disorder. Proper diagnosis and treatment of these patients with panic disorder may be expected to substantially reduce their psychosocial morbidity.

The significance of 2,3-DPG in red blood cell transfusions

This review will begin by giving the highlights of the history and explain development of the basic science knowledge of hemoglobin chemistry, function, and physiology. The necessary involvement of red cell metabolism, as it pertains to the maintenance of 2,3-diphosphoglycerate (2,3-DPG) levels, both normally and under the perturbed and experimental conditions of blood storage, will be given as part of the basic science data. The clinical science and transfusion data will comprise the main critical aspects of the paper. Analysis and comment of over 20 studies will be given on the effects of animal and human transfusions with altered 2,3-DPG levels. Decreased survival and organ function have been demonstrated with transfusion of low 2,3-DPG red cells, with or without anemia, in the conditions of exercise, shock, hypotension, ischemia, cardiac surgery, hypoxia, sepsis, and acidosis. By critical analysis of these studies, recommendations on general and specific patient needs for red cell transfusions with normal or high 2,3-DPG levels are given.

Regional myocardial blood flow in patients with chest pain syndromes and normal coronary arteriograms

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