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Biomedical subjects

R Mee

Publications and source records attributed to R Mee.

5 recordsLinked to original sources

A cluster of necrotizing enterocolitis in term infants undergoing open heart surgery.

BACKGROUND: Necrotizing enterocolitis (NEC) is a serious gastrointestinal disease of unknown cause that predominantly affects premature infants, but it has been reported in term infants with congenital heart disease. METHODS: In August and September of 1997, 4 cases of NEC in term infants with congenital heart disease were identified among 24 infants undergoing cardiac surgical procedures at our institution. Because nosocomial NEC had not previously been identified among infants in our pediatric intensive care unit, a case-control study was conducted to identify risk factors for NEC. All infants less than 4 months old undergoing cardiac surgery without development of NEC during the epidemic period were selected as controls. RESULTS: The only significant risk factor associated with case-infants was a higher mean temperature gradient (rectal/toe) during the immediate 12-hour postoperative period (4.0 degrees C vs 2.0 degrees C, P <.01). Urine output was higher in control-infants in this postoperative period, although not statistically significant (11.9 mL/h vs 6.1 mL/h, P =.15). CONCLUSION: Although an infectious etiology cannot be ruled out, the cases of NEC in infants with congenital heart disease after cardiac procedures may have resulted from mesenteric ischemia associated with a low perfusion state in the perioperative period.

Anti-Bacterial Agents↗

ECMO in newborn infants: the Melbourne experience.

At the Royal Children's Hospital, Melbourne, extracorporeal membrane oxygenation (ECMO) has been used in the treatment of newborn infants with life-threatening respiratory or cardiac failure since May 1989. The main indications for the use of ECMO are that the disease is reversible, the surviving infant is likely to be normal and there is an 80% likelihood of death without ECMO. Sixteen of 22 (73%) newborn infants have survived at least 6 months after ECMO. Fourteen of 16 (87.5%) infants receiving ECMO (who did not have a congenital diaphragmatic hernia) were functionally normal survivors; the other two infants died. Two of six infants with congenital diaphragmatic hernia who received ECMO were discharged and survived to have normal neurological and respiratory function at 6 month follow up. These results are similar to results from other centres internationally. It would appear that ECMO is a useful therapy for near-term newborn infants with otherwise fatal cardiorespiratory failure.

Australia↗

Contractile function in chronic gradually developing subcoronary aortic stenosis.

Whether hypertrophied cardiac muscle functions normally or abnormally is a point of controversy in the literature. Most animal studies showing depressed performance of hypertrophied cardiac muscle have used experimental methods in which hypertrophy was produced by acutely imposing a pressure overload on the left or right ventricle, which may cause myocardial injury. To assess the possibility that chronic, slowly developing hypertrophy is associated with normal myocardial function, we developed an experimental model in which increased afterload is imposed gradually on the left ventricle in the dog. A snug band was placed around the aorta beneath the left coronary artery in puppies without producing a stenosis. As the puppies grew, relative aortic stenosis developed as increased cardiac output flowed across that fixed outflow area. One group (group A) of six puppies was banded early, whereas a second group (group B, five puppies) was banded late and served as controls. Left ventricular weight (g) to body weight (kg) ratio remained normal in group B animals (3.9 +/- 0.14), whereas this ratio was increased to 5.3 +/- 0.24 (P < 0.001) in group A animals indicating development of moderate cardiac hypertrophy. Ejection fraction, dP/dt, Vcf, and stroke work per gram of myocardium were virtually identical in both groups. We conclude that moderate, gradually developing cardiac hypertrophy as produced by this model is associated with normal myocardial contractile performance.

Animals↗

Functional comparison of coronary bypass grafts of the saphenous vein and internal mammary artery.

The magnitude and distribution of myocardial blood flow through a saphenous vein (SV) bypass graft and an internal mammary artery (IMA) graft (diameter greater than or equal to 2 mm) into the same left anterior descending coronary artery (LAD) (diameter congruent to 1.5 mm) were determined at rest, with atrial pacing, and with elevated left ventricular end-diastolic pressure (LVEDP) in 18 dogs. Blood flows through the native LAD, SV, and IMA grafts were similar in the resting heart. With atrial pacing (heart rate = 150% of control), flow in both the SV and IMA grafts increased but the difference was not significant. With elevated LVEDP (20 mm Hg) produced by transfusion, flow in both SV and IMA grafts increased, but, again, these increases were not significantly different. The SV and IMA bypass grafts have similar flow rates at rest and during increased functional demand, provided the grafts are larger than the vessels into which they are placed.

Animals↗