Single Center Retrospective Evaluation of Coronary Artery Fistula Outcomes.

There is a paucity of literature describing long-term outcomes of patients with coronary artery fistula with most manuscripts focusing on those requiring interventions. We describe single-center outcomes of coronary artery fistulas including those not requiring intervention. We performed a retrospective review of the electronic medical record and identified all patients with a diagnosis of coronary artery fistula over the last 10 years. 158 patients were identified with a coronary artery fistula. The mean age at diagnosis was 5.8 years (SD ± 5.9). There was a male (55%, n = 87) predominance. Concomitant congenital heart lesion was present in 49% (n = 77) and a genetic anomaly was found in 18% (n = 29). No ischemic changes on electrocardiogram or ECG-stress test were observed. The mean follow-up was 5.0 (SD ± 3.8) years. Most patients (94%, n = 149) did not undergo an intervention. Of those 63% (n = 94) had at least one follow-up echocardiogram. There was spontaneous coronary artery fistula closure in 44% (n = 41), 8% (n = 8) decreased in size, and 48% (n = 45) were unchanged. No patient had enlargement of the coronary artery fistula over time. Additionally, tiny and small coronary artery fistulas showed no significant clinical changes in coronary artery dimensions, left ventricle dimensions and function over time. Seven patients required intervention; two patients underwent surgical ligation and five underwent catheter-based intervention. Most patients with coronary artery fistula in our cohort did not require intervention and over half either closed spontaneously or decreased in size with routine follow-up.

Premature closure of the foramen ovale associated with aortic stenosis, left ventricular dilation with thrombus, and early mortality.

Premature foramen ovale (FO) closure has been postulated as a cause of hypoplastic left heart syndrome. We suggest that premature FO closure is also associated with left ventricular (LV) dilation and LV thrombus formation, and that FO closure in patients with aortic stenosis and LV dilation is a secondary event that occurs later in gestation than that seen with the hypoplastic left heart.

Congenital coronary artery fistulae: a review of 18 cases with special emphasis on spontaneous closure.

Between 1972 and 1990, 18 patients (median age 3 years, range 0.1-14 years) with coronary artery fistulae (CAF) were seen at this institution. Of the 16 patients without associated heart defects, two patients presented with congestive heart failure and the remaining 14 were asymptomatic. Fifteen patients had normal origin of two coronary arteries. Two patients had atresia of the proximal right coronary artery and, in one patient, the right coronary artery originated from the left main coronary artery. The QP/QS ranged between 1.0 and 2.8, with a mean of 1.4. Fifteen patients underwent operative closure without any deaths. One patient is being followed medically at present. Two patients showed spontaneous clinical improvement of CAF (complete closure in one and near complete in the other) and remained asymptomatic during a decade of follow-up. Review of the literature suggests operative closure of symptomatic and asymptomatic small CAF during childhood. However, the natural history of minute CAF remains unclear. In addition, symptoms from CAF may spontaneously improve with time.

Regional blood flow distribution during extracorporeal membrane oxygenation in rabbits.

To study regional blood distribution during extracorporeal membrane oxygenation, we stabilized three groups of five rabbits each (3 to 5 kg) on venoarterial bypass at a flow rate of 30 ml/kg/min. Albumin aggregates (15 to 30 microns) labeled with technetium 99m were injected into the left ventricle during bypass (ventricle), the perfusion cannula during bypass (cannula), and the left ventricle with no bypass (control). Animals were put to death, organs were removed, and the percent distribution was determined with a gamma camera. The Student Newman-Keuls test was used for statistical comparisons. Distribution to both the heart and brain in the cannula group were decreased from control by 55% and 35%, respectively. Distribution to the brain in the ventricle group was also decreased from control by 39%. Intestinal distribution was elevated above control in the ventricle group by 37%, whereas musculoskeletal distribution was elevated 33% above control in the cannula group. No significant changes were noted for the kidneys, stomach, or liver. These data suggest that overall perfusion of some vital organs may be significantly reduced during low-flow extracorporeal membrane oxygenation, specifically in the case of the heart and brain, which may be deprived of oxygenated blood.

Is heparin necessary for extracorporeal circulation?

To explore the possibility of extracorporeal circulation (ECC) without heparin, we performed veno-arterial extracorporeal membrane oxygenator procedures for a five hour period on a total of 15 rabbits in three groups. Blood flow rates were maintained at 125 ml/min with a standard roller pump through 1/4 inch PVC tubing and a 0.4 m2 SciMed membrane oxygenator. The rabbits in Group 1 received a standard dose of heparin, while no form of anticoagulation was used in Group 2. The tubing and membrane surfaces in Group 3 were modified by a glutaraldehyde crosslinked albumin-heparin complex with no systemic heparinization. Blood samples were obtained for activated clotting time, platelet count, and blood gas determinations. Circuits were evaluated for thrombosis, and samples of lung and kidney were examined histologically for emboli. There were no statistically significant differences among the three groups for any of the quantitative parameters. Moderate thrombus formation was visually detected in some areas of stagnation in the nonheparinized systems, while the albumin coating appeared to inhibit thrombus formation in regions of moderate and high blood flow. These results do not reflect any significant benefit of either the albumin-heparin coating or systemic heparinization during short-term ECC.

Prolonged extracorporeal membrane oxygenation in sheep with a hollow-fiber oxygenator and a centrifugal pump.

ECMO with a roller-pump employs two potentially thrombogenic devices: the servoregulator bladder and heat exchanger. To eliminate these we used an 0.8 m2 Capiox II hollow-fiber oxygenator ventilated with warmed humidified oxygen and a Bio-Medicus centrifugal pump with a 1/4 inch head at a flow of 250 cc/min in six sheep during 96 hr of ECMO each. Oxygenator performance and plasma Hgb were determined, as were the volume, electrolyte, and protein content of fluid accumulating in the gas phase of the oxygenator. Mean oxygen transfer was 15.78 +/- 3.15 ml/min, and mean differences in PaO2 between blood entering and leaving the oxygenator was 360 +/- 49 mmHg. Mean plasma Hgb was 24.7 +/- 12.8 mg/dl. Fluid in the gas phase of the oxygenator was less than 75 ml/day and contained no albumin, protein, sodium, potassium, or chloride. Centrifugal pumps have been associated with hemolysis at low flows, but this may have been due to the simultaneous use of silastic membrane oxygenators that have high resistance. Hollow-fiber oxygenators have been associated with early failure of gas exchange and fluid accumulation in the gas phase. This may have been due to ventilation with dry gas. We conclude that a hollow-fiber oxygenator and a centrifugal pump can provide excellent gas exchange, acceptable hemolysis, and little fluid loss.