Saudi Journal of Anaesthesia

LETTER TO EDITOR
Year
: 2015  |  Volume : 9  |  Issue : 2  |  Page : 225--226

Iatrogenic ascending aortic obstruction in the neonate: Significance of pressure gradients across the aorta


Madan Mohan Maddali 
 Department of Anesthesia, Royal Hospital, Muscat, Oman

Correspondence Address:
Dr. Madan Mohan Maddali
Royal Hospital, P.B. No: 1331, P.C: 111, Seeb, Muscat
Oman




How to cite this article:
Maddali MM. Iatrogenic ascending aortic obstruction in the neonate: Significance of pressure gradients across the aorta.Saudi J Anaesth 2015;9:225-226


How to cite this URL:
Maddali MM. Iatrogenic ascending aortic obstruction in the neonate: Significance of pressure gradients across the aorta. Saudi J Anaesth [serial online] 2015 [cited 2020 Oct 1 ];9:225-226
Available from: http://www.saudija.org/text.asp?2015/9/2/225/152898


Full Text

Sir,

Aortic obstruction secondary to aortic cannulation is a known entity that is seldom reported. [1] We would like to report one such case in a neonate following surgical correction of a ventricular septal defect (VSD) and a hypoplastic aortic arch.

A 7-day-old neonate (sex: Male, weight: 2.3 kg, height: 37 cm) on alprostadil (prostaglandin E1) infusion (10 ng/kg/min) underwent perimembranous VSD closure with repair of hypoplastic arch via a median sternotomy on cardiopulmonary bypass (CPB). Invasive arterial blood pressure was monitored in the right brachial artery.

Cardiopulmonary bypass was instituted with a single aortic cannula and bicaval venous cannulae. Aortic cannulation was performed directly into the ascending aorta at the root of the innominate artery initially and later the aortic cannula was advanced into the right innominate artery during aortic arch repair. Arch repair was performed under deep hypothermia and circulatory arrest (32 min) with antegrade cerebral perfusion. VSD was closed after re-establishing circulation. The baby was separated from CPB easily on milrinone infusion (0.4 μg/kg/min) at normothermia. The arterial pressures in the right brachial artery were well recordable with good wave form prior to and on CPB. But after separation from CPB the arterial pressure wave appeared dampened. Direct pressure recordings in the ascending aorta proximal to the aortic cannulation site (70/35 mmHg, mean: 45 mmHg) and distal to the arch repair (60/30 mmHg, mean: 40 mmHg) were recorded. Relying on the direct aortic root pressure measurements, the aorta was decannulated and the purse string sutures tied. As a delayed sternotomy closure was planned, a 22G × 8 cm polyurethane catheter (Vygon [UK] Ltd) was placed in the ascending aorta for direct pressure monitoring. Postoperatively, the brachial artery pressures did not improve.

Postoperative transesophageal echocardiography (Philips iE33 xMATRIX Ultrasound System with S8-3t micro probe) with color Doppler demonstrated the site of narrowing in the ascending aorta with turbulent flow just below the innominate artery origin [Figure 1] with a 60 mmHg gradient approximately [Figure 2]. The child was transferred to the operating room for a reoperation.{Figure 1}{Figure 2}

On this occasion the right innominate artery was cannulated through a 3.5 mm GORE-TEX ® (W. L. Gore and Associates, Inc., Newark, Delaware) vascular graft. On hypothermic CPB with circulatory arrest (20 min) and with antegrade cerebral perfusion, the earlier aortic cannulation site was widened with a bovine pericardial patch (St. Jude Medical Inc., Minnesota, USA) which abolished the gradients between the ascending aorta, right brachial artery and the femoral artery. The child had a turbulent postoperative course that necessitated prolonged mechanical ventilation.

The aortic pressure gradient was caused by the tying of the aortic purse string after aortic de-cannulation that produced an inadvertent narrowing of the ascending aortic lumen. With the aortic cannula in place, there was minimal gradient between the ascending aorta and the segment of aorta distal to the repair as confirmed by direct arterial pressure measurements.

The importance of simultaneous invasive arterial pressure monitoring of right upper and lower limbs in neonatal aortic arch repairs has been highlighted earlier. [2] When femoral artery is cannulated, constant vigilance is essential for identifying hypoperfusion related problems and regular Doppler examination would aid in recognizing early changes in perfusion. It is also important that these invasive lines should be removed at the earliest once their purpose is served.

Since we did not have a femoral arterial pressure line, a final direct pressure recording of the distal aorta prior to skin approximation, would have identified the problem avoiding a reoperation.

In conclusion, arguable as it is and difficult as it may often be, simultaneous monitoring of right upper and lower limb arterial pressures should be considered in surgical correction of hypoplastic aortic arch and coarctation of the aorta. It is important that enough attention is devoted towards significance of intraoperative pressure gradients across the aortic arch and the etiology for these gradients should be sought for diligently. Whenever feasible, interrogation of the ascending aorta and aortic arch by intraoperative transesophageal echocardiography would help in assessing the adequacy of repair as well as identify other surgical conundrums.

References

1Magner JB. Complications of aortic cannulation for open-heart surgery. Thorax 1971;26:172-3.
2Maddali MM, Valliattu J, al Delamie T, Zacharias S. Selection of monitoring site and outcome after neonatal coarctation repair. Asian Cardiovasc Thorac Ann 2008;16:236-9.