Relation between coronary "steal" and contractile function at rest in collateral-dependent myocardium of humans with ischemic heart disease.

BACKGROUND: We tested the hypothesis that rest asynergy in collateral-dependent myocardium correlates with coronary steal. METHODS AND RESULTS: PET with [13N]ammonia measured myocardial blood flow and flow reserve in 15 patients with symptomatic chronic ischemic heart disease. Coronary angiography assessed stenosis severity and collateral blood supply. Echocardiography or contrast ventriculography evaluated regional wall motion. Collateral-dependent segments with normal flow at rest and supplied by coronary vessels having /=0.15 mL. min-1. g-1 versus rest. Blood flow at rest in asynergic, collateral-dependent segments with steal (1.15+/-0.35 mL. min-1. g-1) exceeded (P<0.0001) that of asynergic segments without steal (0.81+/-0.24) and those with normal contraction (0.77+/-0.18). Although the flow reserve ratio of segments with normal contraction (1.8+/-0.8) exceeded that of asynergic ones with (0.6+/-0.1) or without (1.3+/-0.4) steal, overlap was great. Correlation between basal contraction and flow reserve ratio in collateral-dependent myocardium was significant but weak (r=0.45, P<0.001). However, segments demonstrating "steal" with adenosine manifested asynergy in 22 of 23 collateral-dependent segments versus 24 of 39 nonsteal segments (chi2=7.10, P<0.01). CONCLUSIONS: Although myocardial flow reserve in collateral-dependent segments with normal contraction exceeded that of asynergic segments, overlap was great. However, in patients with angina or congestive heart failure, left ventricular segments demonstrating steal with adenosine almost always exhibit asynergy at rest. Thus, coronary steal may play an important role in the pathogenesis of chronic contractile impairment at rest, whereas simple reduction of flow reserve may be less important in selected patients.     

The distribution and severity of coronary artery disease and left ventricular dysfunction among patients with single coronary artery disease and angina pectoris

The distribution and severity of coronary artery disease and left ventricular dysfunction were evaluated in 103 patients with single coronary artery disease and angina pectoris. The coronary arterial patterns were separated into right (76), mixed (18), and left (9) systems depending upon the blood supply to the inferior surface of the left ventricle. The following relationships were noted: (1) In patients with single coronary artery disease and angina pectoris, coronary arterial lesions are similar among right, mixed, and left systems. (2) In order of frequency, single coronary artery disease occurred most commonly in the left anterior descending coronary artery (55), next most commonly in the right coronary artery (36), and least commonly in the circumflex/obtuse marginal coronary artery (12). (3) Left ventricular wall motion abnormalities were seen in descending order of frequency: patients with right coronary artery (50%), left anterior descending coronary artery (36%), and circumflex/obtuse marginal coronary artery (25%) disease.     

Alpha-fetoprotein levels in normal adults.

Alpha-fetoprotein (AFP) is a fetal specific glycoprotein normally produced primarily by the fetal liver. Normally, AFP levels decline rapidly after birth, reaching undetectable levels (less than 10 ng/ml) within several months after birth. The authors have developed a more sensitive radioimmunoassay, which has allowed them to study low levels of AFP in normal adults and to determine factors which may affect its normal level. Two hundred and seventy normal Houston blood donors were screened for the absence of hepatitis B and normal ALT levels. The mean AFP level was 3.04 ng/ml +/- 1.9 SD. There was a statistically significant higher level in men compared to women (p less than .004). Regression analysis demonstrated a statistically significant increase of AFP levels with age both in men (p less than .05) and in women (p less than .01). These data delineate the normal level of serum AFP in normal adults in the United States. With the normal level now defined, it becomes possible to compare levels in different populations including those exposed to hepatotoxins or hepatocarcinogens in the environment.     

Interleukin-10 promoter polymorphisms in rheumatoid arthritis and Felty's syndrome

OBJECTIVE: To examine whether promoter polymorphisms associated with variation in interleukin-10 (IL-10) production are relevant to the development of rheumatoid arthritis (RA) or Felty's syndrome (FS). METHODS: DNA was obtained from 44 FS patients, 117 RA patients and 295 controls. The promoter region between -533 and - 1120 was amplified by polymerase chain reaction, and polymorphisms detected by restriction enzyme digest or sequence-specific oligonucleotide probing. RESULTS: We found no significant difference in allele or haplotype frequencies between the groups. CONCLUSION: There is no association between FS or RA and these recently identified IL-10 promoter polymorphisms. Other genetic or environmental factors could explain the alterations in IL-10 levels seen in these conditions.      

Evidence of reduced resting blood flow in viable myocardial regions with chronic asynergy

OBJECTIVES

We tested the hypothesis in patients (n = 24) with ischemic heart disease that chronic contractile dysfunction occurs in myocardial regions with true reduction in rest blood flow.

BACKGROUND

Whether viable myocardial regions with chronic contractile dysfunction have true reduction in rest myocardial blood flow is controversial.

METHODS

Positron emission tomography (PET) ¹³N-ammonia was used to measure myocardial blood flow in combination with ¹⁸F-fluorodeoxyglucose (¹⁸FDG) to assess myocardial viability. Viability also was assessed by dobutamine echo and recovery of function after coronary artery bypass grafting (CABG). Segments (n = 252) were selected based on PET measured reduced resting blood flow and rest asynergy on echo.

RESULTS

Regional myocardial viability was present in 20 of 23 patients by PET, 13 of 23 by dobutamine echo and 10 of 11 by postrevascularization criteria. Rest blood flow in normal regions was 1.14 ± 0.52 ml/min/g and by definition exceeded (p < 0.005) that in both viable (0.48 ± 0.15; N = 8 patients) and nonviable (0.45 ± 0.14; N = 8 patients) regions (post-CABG criteria), which did not differ. Correction of rest myocardial blood flow in viable asynergic segments, only, for fibrosis and incomplete tracer recovery raised the level to 0.67 ± 0.21 (p < 0.005 vs. normal). Finally, evidence of both stunning (rest asynergy with normal flow) and hibernation was present in 15 of 23 (65%) patients.

CONCLUSIONS

Reduced rest blood flow in viable myocardial regions with chronic asynergy is common and cannot be accounted for by partial volume effect. Thus, hypotheses concerning physiologic mechanisms underlying chronic contractile dysfunction should consider the role played by chronic reduction of basal myocardial blood flow.     

Prognosis following interventional therapy for acute myocardial infarction: utility of dipyridamole thallium scintigraphy.

A variety of methods for risk stratification after acute myocardial infarction have been successfully employed, however, little attention has been focused on patients who have received reperfusion therapy. The present report examines the utility of dipyridamole thallium scintigraphy in the prediction of late cardiac death or recurrent myocardial infarction in patients who have received thrombolytic therapy. Prospectively, 71 patients who presented with myocardial infarction and were treated with recombinant tissue plasminogen activator (and frequently percutaneous transluminal coronary angioplasty) were enrolled in the study. The primary end points during the follow-up period of nearly 2 years were recurrent infarction or death, which occurred in 10 patients. Although cardiac events were significantly related to either the performance of late myocardial revascularization or the presence of a residual coronary artery stenosis at discharge, no scintigraphic variable was found to be predictive of myocardial infarction or death. Thus, this report is the first to suggest limitation of scintigraphic techniques with regard to prognostic value in myocardial infarction survivors treated with reperfusion techniques. This selected population may have physiologic differences as compared with post-infarction studies performed before the advent of thrombolytic agents. Caution is therefore advised in extrapolating results of earlier reports to the ever increasing percentage of patients receiving recannalization therapy.     

An ambulatory ventricular function monitor: validation and preliminary clinical results

A device for the continuous measurement of left ventricular (LV) function was tested in a series of 34 subjects. The instrument consisted of 2 arrays of radiation sensitive cadmium telluride detectors held in place over the region of the left ventricle and lung by a vest-like garment (hence the name VEST). The VEST electronic instrumentation included analog-to-digital converters, a battery pack, microprocessor and gating device, which were worn in a back pack. Data generated by the VEST, including the digitized average electrocardiogram, RR interval, counts/13 ms in each radiation detector, and time since commencement of data recording, were recorded on a cassette tape recorder every 2 minutes for subsequent analysis. At the conclusion of conventional multigated blood pool imaging, the VEST was positioned and worn by the subjects while supine, standing in place and walking. The correlation of ejection fraction calculated independently from the VEST and scintillation camera data was greater than 0.95. The inter-record reproducibility of the ejection fraction measured by the VEST in sedentary subjects was less than 3%.