Myocardial infarct imaging after cardiac surgery.

One hundred and nineteen patients undergoing cardiac surgery had postoperative myocardial imaging performed with technetium pyrophosphate in order to assess the incidence of perioperative myocardial infarction. Fifty-six patients had only coronary artery bypass graft (CABG) surgery, of whom 13(23%) had a positive scintigram. Thirteen patients had CABG with other cardiac surgery and six (46%) had a positive scintigram. Fifty patients had other cardiac surgery but no CABG, and of these eight (16%) had a positive scintigram. The overall incidence of positive scintigrams was 23%, whereas definite or probable ECG diagnosis of infarction was present in 14 patients (12%). Serum levels of cardiac enzymes were higher in patients with positive scintigrams, but this finding did not consistently reach statistical significance. The use of a left ventricular vent during surgery did not correlate with a positive scintigram, nor did the total time on cardiopulmonary bypass or aortic cross-clamping. Patients having cardiac surgery, including CABG and valve replacement, have a 23% overall incidence of positive scintigrams. This suggests that the incidence of infarction after cardiac surgery is higher than can be recognized from the conventional criteria of ECG and enzyme changes.

Demonstration of surgical portasystemic venous shunts by scintisplenoportography.

Scintisplenoportography (SSP) was used to assess shunt patency in 15 patients with surgically created portasystemic venous shunts and proved to be a simple, safe and accurate technique for demonstrating the patency of both mesocaval "H" grafts and distal lienorenal shunts. SSP was as accurate as angiography in confirming shunt patency but was simpler to perform and resulted in less radiation exposure to the patient. The direction and distribution of blood flow within the splanchnic venous system was different to that obtained by angiography. It is postulated that SSP may well reflect portal haemodynamics more accurately than angiography. In patients with patent mesocaval "H" grafts SSP demonstrated the complete diversion of splanchnic venous blood through the shunt into the systemic venous circulation. This suggests that the mesocaval "H" graft is haemodynamically similar to other side to side portacaval shunts.

Imaging of acute myocardial infarction using technetium 99m labelled phosphate compounds.

Technetium 99m pyrophosphate or polyphosphate administered intravenously soon after acute myocardial infarction produces positive images of the area and extent of myocardial necrosis. Forty-four patients have been studied of whom 39 had myocardial infarction. There was good correlation of the site and extent of infarction as indicated by the scintigram with electrocardiogram and cardiac enzyme criteria.

Segmental renin sampling and partial nephrectomy in renal hypertension.

Selective renin sampling from renal vein tributaries identified a high-renin source in the lower pole of the left kidney in a 16-year-old boy who had gradually developed hypertension after blunt left renal trauma. Localized renin secretion from the ischemic pole was associated with suppression of renin secretion from both the contralateral kidney and the normal part of the affected kidney. Removal of ischemic tissue by partial nephrectomy produced sustained correction of hypertension. The findings indicate that segmental renin sampling can define indications for partial nephrectomy in renal hypertension.