Transesophageal echocardiographic monitoring of myocardial ischemia during vascular surgery.

Transesophageal echocardiography (TEE) was used to detect segmental ventricular wall motion abnormalities (SWMAs) associated with ischemia in 49 high-risk patients who had 50 major vascular procedures, including 23 infrarenal aortic, five suprarenal aortic, 14 carotid, seven distal, and one axillofemoral reconstructions. A modified gastroscope tipped with an echocardiographic transducer was inserted into the esophagus and positioned behind the heart to obtain a reproducible cross-sectional view of the left ventricle at the level of the papillary muscles. Twelve patients (24%) had SWMA at baseline, probably representing areas of old infarction. Fourteen patients (28%) had new intraoperative SWMAs. Ten of 14 patients were successfully treated and wall motion was normalized. One of the four patients with persistent SWMA suffered a nonfatal subendocardial infarct; another patient suffered intraoperative cardiac arrest and died. No infarcts were documented in the 10 patients successfully treated. The mortality rate in the entire high-risk group was 6%. Alterations in ventricular wall motion were noted in almost 50% of high-risk patients undergoing major vascular surgery. Seventy-one percent of acute SWMAs were reversed without any evidence of myocardial infarction. TEE allowed early recognition of evolving myocardial ischemia and facilitated immediate and specific fluid and pharamcologic interventions. Continued application of this technique may reduce the incidence and morbidity of perioperative cardiac complications.

Regulation of intestinal blood flow with increased intraluminal pressure.

To better characterize the mechanisms which regulate intestinal blood flow (IBF), we studied the effects of gradual and rapid increases in intraluminal pressure (LP) in anesthetized canines. Polarographic measurements of hydrogen washout allowed repeated assessment of IBF (ml/min X g) in control (CL) and distended (DL) autoperfused small intestinal loops. In group I (n = 7) graded increases in LP (mm Hg) were produced by saline inflation. In group II (n = 4), IBF was measured before and after intraarterial aminophylline (adenosine blockade); LP was then rapidly raised to 24 mm Hg. IBF was unchanged by time (CL 0.64 +/- 0.24) or gradual distension (DL 0.65 +/- 0.28 at mean maximal LP = 26). Aminophylline did not change IBF at LP = 0. Rapid distension after adenosine blockade was accompanied by immediate increases in IBF (0.96 +/- 0.41, P less than 0.05) and decreased resistance (50 +/- 25% control). IBF is maintained despite gradual increases in luminal pressure. Blockade of adenosine, an intestinal vasodilator, does not inhibit this response; hyperemia associated with rapid distension is not impaired. We conclude that autoregulation of IBF during distension is not accomplished by an adenosine mediated metabolic mechanism.

Effect of pentobarbital and hemorrhage on renal autoregulation.

Renal blood flow and hemodynamic autoregulation were assessed in seven chronically instrumented canines studied in the conscious state and after pentobarbital anesthesia administration (30 mg/kg). The effects of acute arterial hemorrhage (10 and 15 ml/kg) were also studied. In the conscious state, no significant changes in autoregulation were observed following 10 mg/kg hemorrhage. With pentobarbital and 10 ml/kg hemorrhage, a significant change in the limits of autoregulation was noted (autoregulatory limit 78.5 +/- 16.6 vs. 88.4 +/- 25.3 mmHg, P less than 0.05). Four animals were also studied in the conscious state following 15 ml/kg acute arterial hemorrhage. In these animals, mean arterial pressure decreased (from 105.0 +/- 11.4 to 87.8 +/- 7.2 mmHg, P less than 0.025) but renal blood flow (from 293 +/- 38 to 272 +/- 65 ml/min) and autoregulatory limit did not change. We conclude that renal blood flow is unaffected by hemorrhage or pentobarbital alone. In the conscious state, renal pressure-flow autoregulation is maintained despite moderate hemorrhage and systemic hypotension. The lower limit of autoregulation is significantly changed by even minor hemorrhage in the pentobarbital-anesthetized state.

Operation for diagnosis and treatment of pericardial effusions.

UNLABELLED: An experience with 32 consecutive patients with pericardial effusions is reviewed and presented. Malignant effusions: Twenty patients had underlying malignancy. Five had no symptoms, nine had ambiguous symptoms, and six had pericardial tamponade. Initial treatment in eight was pericardiocentesis, which provided diagnosis and treatment in one but was clinically unsuccessful in seven and caused right ventricular puncture in one. Subxiphoid pericardial window in 19 patients showed malignant involvement in six but documented a nonmalignant effusion in 13. There were no operative complications, and no effusions have recurred with long-term follow-up. Only two patients with true malignant effusions had significant long-term survival as compared with 11 of 13 with benign effusions. Uremic effusions: Six patients with renal failure required intervention, three for hemodynamic compromise and one for possible infection. Diagnostic pericardiocentesis documented a sterile effusion in one patient. Five patients had subxiphoid pericardial window without recurrence of effusion. One patient required reexploration for rectus muscle bleeding. Other effusions: All six patients had hemodynamic compromise. Pericardiocentesis was successful in three of four patients but effected resolution in none. Subxiphoid pericardial window was performed in all. The effusion recurred in a patient with periarteritis nodosa, and a patient with viral myocarditis developed a left ventricular pseudoaneurysm that required operation. CONCLUSIONS: Subxiphoid pericardial window provides definitive diagnosis and treatment for pericardial effusions of all causes with low morbidity rates whereas pericardiocentesis is safe but usually ineffective/unproductive; many effusions in patients with cancer are not related to malignant pericardial involvement and documentation is important for treatment planning.