G Lund

Transcatheter closure of patent ductus arteriosus in piglets

To better determine the risks of transcatheter closure of a patent ductus arteriosus (PDA), a model of PDA was made in newborn piglets by using 5- to 7-mm angioplasty catheters to dilate the probe PDA. This maneuver resulted in a permanent PDA in most piglets. Four to 6 weeks later PDA closure was attempted using the Rashkind PDA occluder. Twelve such procedures were attempted, using clean but nonsterile technique. Nine of 12 PDAs were successfully closed. Two failures were the result of inability to successfully traverse the PDA. This problem was solved by using a long sheath to position the device properly. Four complications occurred, all related to device release: left pulmonary artery embolization in 1 case, femoral artery embolization in 1, torn pulmonic valve cusp in 1 and lodgment of a prosthesis on a pulmonic valve cusp. Two successfully implanted devices were infected at necropsy. This study demonstrates the value of a piglet model in testing transcatheter PDA occlusion devices, the importance of sterile technique in such procedures, the hazards of device retrieval through the right heart and the feasibility of transcatheter PDA closure.

Retrieving the Amplatz retrievable vena cava filter.

The new Amplatz retrievable filter was placed 15 times into the inferior vena cava (IVC) of 7 dogs. Retrieval of the filter was attempted in 11 cases after 1 week and in 3 cases after 2 weeks. The retrieval was successful and without complication in all 14 cases. The 15th placement resulted in thrombotic occlusion of the IVC, and no retrieval was attempted.

Radiologic diagnosis of wandering spleen complicated by splenic volvulus and infarction

Wandering spleen is a rare condition caused by malattachment of the dorsal mesogastrium. This condition is prone to torsion of the splenic pedicle leading to splenomegaly, hypersplenism, and infarction. Preoperative diagnosis can be suggested radiologically. A case of wandering spleen is reported and its embryologic, clinical, and radiographie features are discussed.

Infantile peliosis hepatis. A case report.

Peliosis in a 13-month-old infant is described. This patient appears to be the youngest reported case. The radiologic diagnosis of peliosis is difficult. The condition may be confused with other more common liver diseases. Peliosis is best assessed angiographically.

377 EFFECT OF VASOACTIVE INTESTINAL PEPTIDE(VIP) ON CEREBRAL BLOOD FLOW IN THE AWAKE PIGLET

VIP relaxes cerebral vessels in vitro. Central nervous system (CNS) blood flow(BF) was measured (radioactive microspheres) in 6 - 8 week piglets during vehicle infusion and at 10 min of VIP (1 μg/kg/min, iv; plasma VIP of 9±2ng/ml). VIP increased heart rate (228±14 vs 136±8 beats/min, p<.001), reduced systemic pressure (64±5 vs 92±3mmHg, p<.001), while CO was unchanged (276±30 vs 261±20ml/min/kg). Caudate nucleus, cerebral gray and white matter BF was reduced by 19 to 25% while regional resistance was unchanged. In contrast, resistance was reduced by 23-34% in the spinal cord, brain stem and cerebellum while BF was unchanged.Values are mean±SE; n=8; *p<0.02 to<0.005 vs ControlThus, VIP induced CNS BF changes in awake piglets are different than in anesthetized animals. Whether this represents differential regional sensitivity to VIP or is a consequence of the systemic effects of VIP is unknown.

CONTINUOUS WAVE DOPPLER AND PDA: THE VELOCITY INDEX

A ratio of mean aortic systolic and diastolic velocities determined by continuous wave doppler (CW) has been shown to correlate with ductal (PDA) % left-to-right shunt (LRS). A new simpler ratio, velocity index (VI), of peak systolic to diastolic velocities can be determined from peripheral arteries without planimetry. Shown to correlate with clinical estimates of PDA-LRS in 22 infants, VI has not been validated by measured LRS. We examined 8 pigs (mean weight 6.1 kg, mean age 23.6 days). PDA was created by balloon catheter dilation. 4 studies were before PDA (no angiographic shunt), 4 acute PDA, and 7 chronic (mean 15.8 days) PDA. Pigs were sedated with ketamine. Left ventricular output (LVO) and LRS were determined using LV injection of 15μm radioactive spheres. LRS was corrected for systemic shunting (11.8%) of spheres. CW was performed over brachial and femoral arteries using a 7.0 MHz probe. LVO ranged from 89 to 453 ml/min/kg. Results (mean ± SD, *p<0.05 v. closed):There was a statistically significant correlation (r=0.88, p<0.01) of VI v. LRS. Diastolic runoff in PDA produces negative peak diastolic velocity in arteries that increases with larger LRS. Our study confirms that VI reflects the size of LRS in PDA although actual LRS cannot be predicted by VI. However, no pig with VI>-0.01 had LRS>40%, similar to clinical findings in infants.