Biomedical subjects

T H Wareing

Publications and source records attributed to T H Wareing.

28 records · Page 2Linked to original sources

PubMed1990

Risks of bilateral internal mammary artery bypass grafting.

Although use of one internal mammary artery (IMA) for coronary artery bypass grafting does not appear to be associated with increased risk, the results with both IMAs are less certain; the potential for a higher incidence of sternal wound infection as a result of devascularization of the sternum is a major concern. During a 42-month interval ending July 1988, 1,566 patients had coronary artery bypass grafting alone or in combination with other procedures: 633 received only vein grafts, 687 had unilateral IMA grafting, and 246 had bilateral IMA grafting. The IMA patients were younger, were more often male, had better cardiac function, and underwent fewer emergent, urgent, or combined procedures than the patients receiving vein grafts (p less than 0.05). Thirty-day mortality was lower among the IMA patients (unilateral IMA group, 2.8%; bilateral IMA group, 3.7%; and vein graft group, 7.9%; p = 0.001). With the exception of sternal wound problems, occurrence rates for postoperative complications among the IMA patients did not differ significantly from or were lower (p less than 0.05) than those among the patients with vein grafts. Sternal infections occurred with greater frequency among the bilateral IMA patients (6.9%) than among the unilateral IMA (1.9%) or vein graft (1.3%) patients (p = 0.001). By univariate analysis, obesity, diabetes, bilateral IMA grafting, and need for prolonged (greater than 48 hours) mechanical ventilation were associated with a significantly higher incidence of sternal infection (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

Use of single internal mammary artery grafts in older patients.

The indications for use of the internal mammary artery as a coronary bypass conduit in older patients are not clearly established. Between January 1985 and December 1988, 786 patients received single internal mammary artery grafts alone (717) or in conjunction with other procedures (69). Of these patients, 341 were 65 years of age or older (mean, 69.3 years). This group was compared with those patients less than 65 years of age (mean, 56.2 years). There were no significant differences between the two groups in the incidence of diabetes mellitus; the number of distal coronary anastomoses; left ventricular wall motion score; the frequency of isolated bypass procedures, reoperations, or emergent operations; or the durations of aortic clamping and cardiopulmonary bypass. The older group contained more women (34.9% versus 20.7%) and more patients with left main coronary artery disease (15.5% versus 9.4%) (p less than 0.01). No significant differences in the frequency of reoperation for hemorrhage, perioperative infarction, neurological deficits, requirements for intra-aortic balloon pumping, sternal wound infections, necessity for prolonged ventilatory support, or 30-day mortality (2.7% versus 3.2%) were observed. The length of postoperative hospitalization was greater in the older group (11.8 versus 10.2 days) (p = 0.02). Blinded histological examination of biopsies from 61 internal mammary artery grafts (34 patients less than 65 years, 27 patients greater than or equal to 65 years) showed no significant differences in luminal area or wall thickness. No significant degenerative changes were observed in either group. We conclude that the use of the internal mammary artery for bypass grafting in older patients is safe and may provide long-term benefit.

Age Factors↗

PubMed1990

Elective hypothermic cardiopulmonary bypass and circulatory arrest for spinal cord protection during operations on the thoracoabdominal aorta.

Resection of aneurysms of the entire descending thoracic aorta and segments of the abdominal aorta is associated with a substantial incidence of spinal cord ischemic injury, particularly in patients with aortic dissection. Since hypothermia has a protective effect on spinal cord function, we evaluated a technique of total cardiopulmonary bypass with periods of hypothermic circulatory arrest and low flow (rectal/bladder temperatures of 15 degrees to 19 degrees C) in five patients requiring replacement of the entire descending thoracic and the upper abdominal aorta and judged to be at high risk for the development of spinal cord injury. All patent lower intercostal and lumbar arteries were preserved or reimplanted during the hypothermic interval. There was one hospital death. None of the four survivors had a new spinal neurologic deficit, renal or cardiac dysfunction, or required reoperation for bleeding. Transfusion of blood products was not excessive. Severe pulmonary dysfunction necessitating tracheostomy occurred in one patient and contributed to his death 7 weeks postoperatively. The remaining three patients are well 8 to 36 months postoperatively. This initial experience suggests that hypothermic perfusion and circulatory arrest can be safely implemented in selected patients who require extensive aortic resections and who are at substantial risk for the development of spinal cord injury. Further evaluation of this technique is warranted.

Adult↗

PubMed1989

Increased plasma oncotic pressure inhibits pulmonary fluid transport when pulmonary pressures are elevated.

Hydrostatic and oncotic pressures are the primary determinants of fluid movement across the pulmonary vascular membrane. The precise role of oncotic pressure in regulating transvascular fluid exchange especially when hydrostatic pressure is high is not known. Awake, adult sheep were instrumented for pressure monitoring and the collection of pulmonary lymph. A left atrial (LA) balloon catheter was utilized to control LA pressure. Statistically significant increases in lymph protein flux were seen with infusion of saline and elevated pulmonary microvascular pressure (Pmv) over elevated Pmv alone (15.3 +/- 1.23 versus 11.2 +/- 1.09 mg/min) concomitant with a decrease in plasma colloid oncotic pressure (COP) (14.9 +/- 0.5 versus 16.9 +/- 0.5 mm/Hg). The protein flux seen with elevated Pmv and saline infusion was blunted when plasma was infused (13.8 +/- 1.58 mg/min) and the plasma COP augmented (18.1 +/- 0.05 mg Hg) but was not statistically different. We conclude that under conditions of stable membrane permeability and elevated Pmv, the plasma COP appears to be an important mechanism for protection against pulmonary edema.

Animals↗

PubMed1989

Aortoesophageal fistula: unusual complication.

We have reported an unusual case of an aortoesophageal fistula between the midthoracic esophagus and the residual wall of an aneurysm of the descending thoracic aorta two weeks after graft replacement of the descending thoracic aorta. A CT scan of the chest after ingestion of water-soluble contrast material documented the fistula.

Aortic Dissection↗

PubMed1985

Amelioration of the deleterious effects of platelets activated during cardiopulmonary bypass. Comparison of a thromboxane synthetase inhibitor and a prostacyclin analogue.

Thrombocytopenia and platelet dysfunction are commonly seen after cardiopulmonary bypass. In addition, the microvascular bed of ischemic myocardium is a potent stimulus for platelet deposition and microvascular plugging. Thus, it would appear theoretically advantageous to provide pharmacologic protection of platelets by inhibiting their response to activating agents and thereby preventing their loss into the extracorporeal circuit; this would further inhibit myocardial platelet deposition and the deleterious effects therein. Twenty-one mongrel dogs were placed on cardiopulmonary bypass with 30 minutes of normothermic global ischemia. They were randomly assigned to receive pretreatment with an infusion of saline (control, n = 8), a thromboxane synthetase inhibitor (RO-22-4679, n = 5), or a prostacyclin analogue that does not produce hypotension (ZK 36,374, n = 8). The platelet count in those animals treated with ZK 36,374 was significantly higher at the end of the experiment than in the control group (102.8 +/- 10.7 X 10(3) versus 69.7 +/- 10.6 X 10(3), p less than 0.01); the animals treated with RO-22-4679 had a platelet count between the other two groups (92.8 +/- 14.8 X 10(30)), which was not significantly different from either. Myocardial platelet deposition was measured with indium 111-labeled platelets. Those animals treated with ZK 36,374 had a much lower level of platelet deposition than the group of controls; again the RO-22-4679 group had values between the other two. Finally, myocardial blood flow after global ischemia and cardiopulmonary bypass, measured with radioactive microspheres, was significantly higher in the ZK 36,374 group than in the control group. We conclude that ZK 36,374 prevents platelet consumption during cardiopulmonary bypass over and above that seen with inhibition of thromboxane synthesis alone. It also prevents deposition of platelets into the myocardium after global ischemia and we presume by that mechanism increases myocardial blood flow.

Animals↗

PubMed1985

Pathophysiology of chronic cyanosis in a canine model. Functional and metabolic response to global ischemia.

To investigate the pathophysiology of chronic cyanosis, we subjected 14 adult mongrel dogs to diversion of the inferior vena cava to the right inferior pulmonary vein. This produced a mean oxygen tension of 42 +/- 2 mm Hg and a calculated right-to-left shunt of 52.0% +/- 3.9%. These animals (Group C) and 15 normal dogs (Group N) were subjected to cardiopulmonary bypass with 20 minutes of normothermic global ischemia. Functional indices studied were rate of rise of left ventricular pressure and the end-systolic pressure/volume ratio. Metabolic status was assessed by obtaining transmural myocardial biopsy specimens for measurement of adenosine triphosphate content. Myocardial blood flow was measured with radiolabeled microspheres. There were no significant differences between Group C and Group N in either functional index or blood flow measurement prior to global ischemia. At 45 minutes after ischemia, Group N animals had a significantly greater rate of rise of left ventricular pressure (at a left ventricular end-diastolic pressure of 0, 5, 10, and 15 mm Hg, p less than 0.025 to 0.05) and subendocarial perfusion (endocardial/epicardial flow ratio 0.961 +/- 0.037 versus 0.815 +/- 0.021, p less than 0.01). At 90 minutes after ischemia, Group N animals exhibited a significantly higher end-systolic pressure/volume ratio (4.9 +/- 0.7 versus 3.0 +/- 0.4 mm Hg/ml, p less than 0.05), rate of rise of left ventricular pressure (at an end-diastolic pressure of 0 to 20 mm Hg, p less than 0.005 to 0.05), and endocardial/epicardial flow ratio (1.065 +/- 0.046 versus 0.829 +/- 0.059, p less than 0.01). No differences in adenosine triphosphate content were found at any sampling period. The Group C left ventricles exhibited no hypertrophy but were significantly dilated compared to Group N (38.8 +/- 0.3 versus 30.1 +/- 0.2 mm, p less than 0.05). Inferior vena cava to pulmonary vein diversion produces cyanosis with left ventricular dilatation but without hypertrophy. It is proposed that abnormal loading characteristics of the left ventricle are responsible for the functional derangements that result from global ischemia.

Adenosine Triphosphate↗

PubMed1983

Carcinoids and the carcinoid syndrome.

The many manifestations of carcinoids will continue to puzzle and intrigue surgeons. Because these are dynamic tumors which produce multiple hormones with many potential side effects, an aggressive surgical debulking of them is advocated. Even in the presence of metastatic disease, some long-term survival can be anticipated. The most debillitating aspect of this tumor to the patient is the carcinoid syndrome. The symptoms occur erratically and are often not well controlled by presently available medication. Although metastatic disease present at diagnosis is most commonly seen with jejunoileal carcinoids, colorectal carcinoids appear to be the most lethal tumors. However, they are rarely associated with the symptoms of carcinoid syndrome. Carcinoids may often be associated with other types of tumors, some of which are known to produce their own hormones. Survival of the patients seems to be related to their other tumor type rather than the primary carcinoid. The clinician should be aware of the strong association of carcinoids with peptic ulcer disease. The ulcer diathesis is probably related to ectopic histamine production and can usually be controlled by cimetidine and antacids, although surgical intervention may be required.

Adult↗

PubMed1979

Hodgkin's cells and attached lymphocytes: a possible prognostic indicator in splenic tumor.

After the purification of Hodgkin's cells by a previously reported method from splenic tumor of 8 patients with Stages III or IV Hodgkin's disease, we have examined the proportions of Hodgkin's cells with attached lymphocytes. All patients were studied 3--5 years after staging laparotomy. Four patients had no recurrent disease; 3 had histologically confirmed recurrent disease; and 1 had clinically suspected recurrent disease (enlarged nodes) but has thus far refused further medical study and care. The proportion of purified Hodgkin's cells which had attached lymphocytes was consistently higher in the patients who were clinically free of disease. The possible biological significance of this observation is discussed briefly and would appear to warrant further investigation of this phenomenon in more patients with splenic tumor than are available to us.

Adolescent↗

PubMedDate not supplied

A model of right ventricular failure after global myocardial ischemia and mechanical left ventricular support.

Postcardiotomy right ventricular (RV) failure after institution of mechanical left ventricular (LV) support is poorly understood. Using a canine model supported by cardiopulmonary bypass (CPB), the animals underwent 30 min of aortic clamping or no ischemia and were weaned to an LV assist device (LVAD). Echocardiographic measurements of LV and RV cavity size off support allowed calculation of percentage change in cavity area (fractional shortening). There were no differences at baseline. After 2 hrs on LVAD, there were significant differences between ischemic and control groups in both LV (38 +/- 12 vs. 61 +/- 6) and RV (15 +/- 3 vs. 55 +/- 12). The ischemic RV also had significantly decreased function compared with the LV (38 +/- 12 vs. 15 +/- 3). The control group demonstrated no differences in ventricular function. The authors concluded that global ischemia diminishes LV and RV function, and this effect is accentuated in the RV after LVAD support. In controls, RV function is not affected by LVAD support, but after ischemia, LVAD support alone often will be inadequate.

Animals↗