Prospective study of blunt aortic injury: helical CT is diagnostic and antihypertensive therapy reduces rupture.

OBJECTIVE: There were two aims of this study. The first was to evaluate the application of helical computed tomography of the thorax (HCTT) for the diagnosis of blunt aortic injury (BAI). The second was to evaluate the efficacy of beta-blockers with or without nitroprusside in preventing aortic rupture. SUMMARY BACKGROUND DATA: Aortography has been the standard for diagnosing BAI for the past 4 decades. Conventional chest CT has not proven to be of significant value. Helical CT scanning is faster and has higher resolution than conventional CT. Retrospective studies have suggested the efficacy of antihypertensives in preventing aortic rupture. METHODS: A prospective study comparing HCTT to aortography in the diagnosis of BAI was performed. A protocol of beta-blockers with or without nitroprusside was also examined for efficacy in preventing rupture before aortic repair and in allowing delayed repair in patients with significant associated injuries. RESULTS: Over a period of 4 years, 494 patients were studied. BAI was diagnosed in 71 patients. Sensitivity was 100% for HCTT versus 92% for aortography. Specificity was 83% for HCTT versus 99% for aortography. Accuracy was 86% for HCTT versus 97% for aortography. Positive predictive value was 50% for HCTT versus 97% for aortography. Negative predictive value was 100% for HCTT versus 97% for aortography. No patient had spontaneous rupture in this study. CONCLUSIONS: HCTT is sensitive for diagnosing intimal injuries and pseudoaneurysms. Patients without direct HCTT evidence of BAI require no further evaluation. Aortography can be reserved for indeterminate HCTT scans. Early diagnosis with HCTT and presumptive treatment with the antihypertensive regimen eliminated in-hospital aortic rupture.

Blunt injuries of the brachiocephalic artery.

Blunt injury of the brachiocephalic artery can pose diagnostic and management problems for the trauma and thoracic surgeon. To arrive at recommendations for dealing with this injury, we reviewed a seven-year experience at our trauma center. Between 1988 and 1995, five patients presented with blunt injuries of the brachiocephalic artery. All patients were stabilized and underwent repair through a median sternotomy with extension of the incision anterior to the sternocleidomastoid muscle. All patients had restoration of flow to the subclavian and carotid arteries utilizing bypass grafts (4) or primary repair (1). All patients survived to leave the hospital with no complications related to the procedure. Postoperative neurologic findings were present before the operative repair. Patients with blunt injuries of the brachiocephalic artery should be stabilized, and circulation of the subclavian and carotid arteries should be restored with graft placement or primary repair. Cardiopulmonary bypass and heparin or temporary shunts were not needed in this series of patients. Complications were related to associated injuries.

Reduction of infarct size with coronary venous retroperfusion.

BACKGROUND: The purpose of this study was to determine whether coronary venous retroperfusion with pressure-controlled intermittent coronary sinus occlusion (PICSO) alone and in combination with coronary venous substrate enhancement using L-glutamate would decrease ischemic damage after surgical revascularization for an acute coronary occlusion. METHODS AND RESULTS: In 40 pigs, the second and third diagonal vessels were occluded with snares for 90 minutes followed by 30 minutes of cardioplegic arrest and 180 minutes of reperfusion with the coronary snares released. During the period of coronary occlusion, 10 pigs received PICSO using a balloon-tipped triple-lumen catheter in the coronary sinus; 10 pigs received PICSO plus oxygenated blood transfused retrograde via the PICSO catheter (7 ml/min), 10 pigs received PICSO plus an oxygenated blood L-glutamate (13 mM) solution, and 10 pigs received neither PICSO, blood, nor L-glutamate through the coronary sinus (unmodified). Hearts treated with PICSO had higher wall motion scores (1.27 +/- 0.33 for unmodified, 2.40 +/- 0.40* for PICSO, 2.45 +/- 0.20* for PICSO plus blood, 2.85 +/- 0.30* for PICSO plus L-glutamate; *p < 0.05 from unmodified where 4 is normal to -1 is dyskinesia), lower area of necrosis-to-area of risk ratio using histochemical staining techniques (73 +/- 4% for unmodified, 27 +/- 4 for PICSO; 18 +/- 2* for PICSO plus blood, 12 +/- 1* PICSO plus L-glutamate; *p < 0.05 from unmodified), significantly less tissue acidosis (pH) compared with the unmodified group (pH, -0.41 +/- 0.13 for unmodified, -0.16 +/- 0.03* for PICSO, -0.19 +/- 0.02* for PICSO plus blood, -0.20 +/- 0.08* for PICSO plus L-glutamate; *p < 0.05 from unmodified). CONCLUSIONS: Coronary venous retroperfusion with PICSO alone and in combination with coronary venous substrate enhancement using L-glutamate significantly decreases ischemic damage during urgent surgical revascularization.

Improved myocardial preservation during cold storage using substrate enhancement.

This study was undertaken to determine whether substrate enhancement with L-glutamate during periods of cold storage would improve ventricular function in transplanted hearts. Thirty-one rabbit hearts were rapidly excised and perfused with Krebs-Henseleit buffer (37 degrees C) on a Langendorff apparatus. They were arrested with hypothermic (4 degrees C), crystalloid, potassium (25 mEq/L) cardioplegia and stored at 3 degrees C for three hours, followed by reperfusion with Krebs-Henseleit buffer for one hour. Hearts were treated in one of several ways: Group 1 (n = 8) did not receive any L-glutamate and serve as controls; group 2 (n = 8) had L-glutamate (4 mmol/L) added to both the cardioplegic and reperfusate solutions; group 3 (n = 5) received L-glutamate only before ischemia; group 4 (n = 5) received L-glutamate only in the cardioplegic solution; and group 5 (n = 5) received L-glutamate only in the reperfusate. Hearts receiving L-glutamate in the reperfusate with or without its addition to the cardioplegic solution (groups 2 and 5) had the best recovery of the first derivative of positive and negative change in left ventricular peak systolic pressure and no significant changes in left ventricular compliance. Pretreatment with L-glutamate alone (group 3) resulted in no better recovery than in group 1 hearts. We conclude that addition of L-glutamate to reperfusate solutions after periods of cold storage for transplantation enhances the recovery of ventricular function.

Determinants of myocardial infarction following emergency coronary artery bypass for failed percutaneous coronary angioplasty.

Acute myocardial ischemia during percutaneous transluminal coronary angioplasty (PTCA) often necessitates emergency coronary artery bypass grafting (CABG) and can result in myocardial infarction (MI). This study was undertaken to determine what factors might predispose to MI following emergency CABG for failed PTCA. Since 1980, 24 patients at Boston University Medical Center have undergone emergency CABG following failed PTCA. In 15 patients (63%), there was postoperative evidence of an MI shown by either ECG or enzyme criteria. Variables that predisposed to a perioperative MI (p less than 0.05) included multivessel PTCA, the presence of multiple vessels with 50% stenosis or more, multivessel CABG, and the presence of new ECG changes immediately following failed PTCA. Variables that did not discriminate between the two groups included age, sex, the specific vessel involved during PTCA, or a previous history of MI. The presence of coronary collaterals did not decrease the incidence of MI. This study suggests that patients with multiple major coronary stenoses in whom acute ECG changes develop following failed PTCA are more likely to sustain a perioperative MI following emergency CABG.