Fontan Procedure at 2,240 m Above Sea Level

Abstract

The modified Fontan procedure represents the final stage of reconstructive surgery for most patients with functionally univentricular hearts. Although outcomes following Fontan procedures performed at sea level are widely reported, less has been documented and reported concerning outcomes in regions at high altitude. To clarify the main features involved, we present our institutional experience with Fontan operations performed in Mexico city (2,240 m above the sea level), with an emphasis on historical evolution of treatment. A retrospective and observational study was undertaken, which included 98 patients over a period of 18 years, and clinical outcomes in terms of morbidity and mortality were analyzed. A change in operative technique from intra-cardiac nonfenestrated Fontan procedure to extra-cardiac fenestrated technique occurred in 2001. Early mortality rates before and after this change in surgical approach were 26% and 4.7%, respectively. The most common morbidity was the occurrence of pleural effusions (98% of patients), which also appears to be a risk factor for operative mortality. Much remains unknown about the pathophysiology of the Fontan circulation at high altitude, and we need to develop morphological study protocols that include pulmonary biopsy to increase our knowledge and inform our therapeutic actions.

Outcomes of the Non-fenestrated Fontan Procedure at High Altitude

“…Its indications, benefits, risks, and long-term effects are still, therefore, a matter of debate. 13 High altitude, however, poses particular problems for the Fontan population because fenestration, usually considered necessary in this setting, 4 can significantly worsen hypoxemia due to low atmospheric P o 2 .…”

“…Although a previous report of the Fontan procedure from a center in Mexico City noticed a decrease in mortality coincidentally in time with the implementation of a fenestration strategy, the study did not analyze other concomitant factors that could have contributed to the overall improvement of the results, as has taken place in most centers. 4 Since high altitude around 2,500 m does not seem to be associated with an increase in PVR, in this situation, fenestration could be used also only in a selective manner in, for other reasons, high-risk patients. In other words, we think this altitude should not be considered a high risk factor since PVR is most likely to be normal.…”

“…High altitude, due to its related hypoxia and increased pulmonary vascular resistance (PVR), 3 has usually been considered a risk factor for mortality for the Fontan procedure 2 and, by some, an absolute indication to perform a fenestration routinely. 4 However, the altitude threshold that should be considered a risk factor has not yet been determined. Progressive altitude decreases atmospheric pressure and partial pressure of oxygen (P o 2 ), 5 and for this reason, when significant, pulmonary venous desaturation may produce systemic arterial desaturation, and a fenestration, with its obligatory right to left shunting, could worsen cyanosis and decrease exercise performance.…”

Early Extubation in a Pediatric Cardiac Surgery Program Located at High Altitude

“…Focusing on univentricular physiology patients, it has been suggested that Fontan and Glenn surgeries might be higher risk procedures and less amenable to EE when performed at high altitudes, due to the direct effects of low PO 2 on SaO 2 and to its potential secondary effects in increasing PVRs. 24,25 However, EE (if possible in the OR) in univentricular heart anatomy patients undergoing either Glenn or Fontan procedures is desirable due to the positive hemodynamic effects for this particular physiology. 26 –29…”

EPAS 1, congenital heart disease, and high altitude: disclosures by genetics, bioinformatics, and experimental embryology

“…The most common defects were patent ductus arteriosus (PDA; about 2/3), atrial septal defects (ASDs; about 1/5), and ventricular septal defects (VSD; about 1/10) with the prevalence of CHD in girls being higher than in boys. The condition of high altitudes may also have some effect on two routine cardiac surgery operations, including Fontan and bidirectional Glenn's anastomosis, although a sum of factors should probably be taken into account (e.g., age) [6][7][8][9]. The Fontan procedure comprises any surgical operation that results in the blood flow of systemic venous blood to the lungs without passing through a ventricle, while the bidirectional Glenn is a common surgical fashion of the second stage of the total cavopulmonary connection (TCPC) surgery where the end of the superior vena cava (SVC) is connected to the side of the pulmonary artery (PA).…”