Brain microemboli during cardiac surgery or aortography

Abstract

We have observed many focal dilatations or very small aneurysms in terminal arterioles and capillaries of 4 of 5 patients and 6 dogs who had recently undergone cardiopulmonary bypass. A smaller number of sausagelike dilatations distended medium-sized arterioles. Two other patients had a small number of the same microvascular changes following proximal aortography. Thirty-four patients and 6 dogs not undergoing cardiopulmonary bypass had none. (A 35th patient who had not undergone cardiopulmonary bypass or aortography showed a small number of dilatations; mediastinal air was a suggested source.) Some of the dilatations exhibited various forms of birefringence. Because most of the dilatations appear empty, we speculate that they are the sites of gas bubbles or fat emboli that have been removed by the solvents used in processing. These microvascular events, occurring only in conjunction with major arterial interventions, may be the anatomical correlate of the neurological deficits or moderate to severe intellectual dysfunction seen in at least 24% of patients after cardiac surgical procedures assisted by cardiopulmonary bypass.

Longer Duration of Cardiopulmonary Bypass Is Associated With Greater Numbers of Cerebral Microemboli

“…16,20 The rapid decline in microemboli found in this study is consistent with observations in dogs showing that after CPB, most microvascular occlusions had disappeared within 7 days, 32,33 and with the observations of Blauth et al 34 that vascular occlusions in the retinas of CPB patients were more numerous during CPB than after CPB.…”

“…In 7 subjects who had left heart catheterization after CPB (data not shown), we found more microemboli than would be expected from CPB alone. This finding is consistent with the fact that left heart catheterization is known to cause cerebral emboli, 20,56 apparently due to the disruption of aortic and coronary artery atheroma. The disruption of aortic or carotid atheroma may release lipid microemboli as well as larger emboli of atheromatous debris and cholesterol crystals.…”

“…Studies of brain microemboli also declined, although the danger of fat microemboli remained. Recognition of this problem was renewed when Moody et al, 20 using alkaline phosphatase staining of the cerebrovasculature, reported finding thousands of small capillary and arteriolar dilatations (SCADs) in all patients who died shortly after CPB, whereas none were found in control subjects. The SCADs could be seen clearly in 3 dimensions.…”

Silent cerebral microemboli occurring during carotid angiography: frequency as determined with Doppler sonography.

“…Digital subtraction angiognaphy of the aortic arch was performed after 10-15 ml of iopamidol R (E. R. Squibb) was injected into each artery for a total of 20 ml at 300 psi. Angiognaphy catheters were used for con- Moody et al [9] observed focal dilatations of small capillanes and arterioles in the brains of patients who had undergone cardiopulmonary bypass. They speculated that these represented gas bubbles or fat emboli.…”

Does hypothermia or hyperventilation affect enflurane MAC reduction following partial cardiopulmonary bypass in dogs?

“…Activation of the complement system with disruption of cell membranes may occur as a result of CPB. , [6][7][8][9][10][11][12][13][14][15][16][17][18][19] In a group of dogs undergoing hypothermic CPB, Johnston et al , 4 found that cerebral blood flow (CBF) was markedly reduced during 150 min of hypothermic CPB and remained so even after rewarming. They saw a small, but significant, rise in intracranial pressure (ICP) but could demonstrate no evidence of brain oedema on the basis of cerebral water content.…”