Internal mammary artery implantation: effect on myocardial lactate utilization

Twenty-three subjects with angiographically documented coronary heart disease were studied by means of arterial and coronary sinus catheterization before and one year after internal mammary artery implantations. The pre- and postoperative patterns of lactate extraction at rest and after isoproterenol stress have been determined and correlated with clinical improvement and angiographic patency of the implant. In group I 13 subjects had implants that were angiographically seen to fill some portion of the coronary circulation. Eight of 11 who produced lactate preoperatively reverted to normal lactate extraction. Two extracted lactate at both studies. All but two had clinical improvement. No deaths occurred over a mean follow-up period of 40 months (range 20 to 64). In group II ten subjects bad implants with no visible connection to the coronary circulation. Only one subject had reversion of lactate production to extraction and two from extraction to production. Seven of ten did not improve clinically. Three deaths occurred over a mean follow-up period of 39 months (range 17 to 53). Agreement has been found between reversion to normal lactate metabolism, angiographic patency, and clinical improvement following internal mammary artery implantation.

Two generations of 13-15 chromosomal mosaicism: possible evidence for a genetic defect in the control of chromosomal replication

An identical nontranslocation autosomal mosaicism occurring in two consecutive generations is presented. A mother and two of her four daughters have been demonstrated to be 46/47 mosaics. The trisomic cells have an extra autosome in the 13–15, or D, group. The proband and one of her sisters reveal varying phenotypic expressions of the trisomic state. The mother and her two other daughters are phenotypically normal. The observation of 46/47 chromosomal mosaicism in man in a pattern which suggests that it is under genetic control necessitates the introduction of a new theory since it cannot be explained by earlier hypotheses which are directed towards understanding the chance occurrence of an individual mosaic. The rapidly accumulating evidence of the nonrandomness of chromosomal abnormalities points towards a possible defect in primary gene control of DNA replication. It is theorized that a gene which regulates the replication of a chromosome in the 13–15, or D, group is defective and that, as a result, this chromosome replicates twice instead of once during some, but not all mitoses, producing a mosaic of trisomic and normal cells. Presumably, the postulated mutant gene is present in the heterozygous state in the affected individuals and behaves as a dominant, with half of the children of an affected parent being abnormal.

Regional myocardial blood flow

A method is described which measures the local effectiveness of the myocardial circulation, expressed as a clearance constant. Uniform clearance constants have been demonstrated in the normal canine and human myocardium. A distinct difference in clearance constants has been demonstrated between the normal canine myocardium and areas of naturally occurring disease. Heterogeneous clearance constants have been found in a majority of human subjects with coronary artery disease-the lowest rates being noted in areas of fibrous aneurysm.