Cardiopulmonary bypass for adults with congenital heart disease: pitfalls for perfusionists

Abstract

The fixed incidence of congenital heart defects and improved survival have resulted in increasing numbers of adults with congenital heart disease (CHD) who have undergone complex repairs and/or palliations. Eventually, there will be more adults with CHD than children. They will require cardiac surgical interventions associated with progression of their CHD or for age-related disease, such as coronary revascularization. During bypass, anatomical shunts may exist within or without the heart. Left-to-right shunts can result in dramatically lower systemic blood flow than pump flow due to 'steal', while pulmonary edema ensues due to excessive pulmonary flow. Right-to-left shunts carry risks of massive air embolism and double or triple venous cannulation may be necessary. Cannulation of composite reconstructed aortas may be difficult, risking dissection or aortic obstruction, and double arterial cannulation may be indicated. Aberrant coronary arterial and venous anatomy may .preclude adequate myocardial preservation with common techniques and can be complicated by aortic insufficiency. Valves and conduits may exhibit failure. Conventional monitoring, such as central venous oximetry, may be misleading. Monitoring, such as serial lactate measurement, near-infrared spectroscopy and transcranial Doppler blood velocity, offer advantages for such patients. The perfusionist needs to be aware of such conditions as much congenital aberrancy may present unexpectedly during cardiac surgery.

Air Embolism

“…According to the literature, gas embolism may occur in cardiac surgery, cardiology, critical care and pulmonology, diving and hyperbaric medicine, endoscopic and laparoscopic surgery, gastroenterology, nephrology, neurosurgery, obstetrics and gynecology, otolaryngology, orthopedics, urology, vascular surgery, etc. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Among these, air embolism occurs more frequently in neurosurgical and otolaryngological procedures when compared to surgical procedures in other specialties.…”

“…There are numerous surgical or other non-surgical invasive procedures where gas embolism has been reported as a complication: (1) needle biopsy of the lung (bronchoscopic or percutaneous), lung resection [15][16][17]24] and radiofrequency ablation of lung cancer [25], (2) arthroscopy and arthroplasty [18,26], (3) gynecological procedures (hysteroscopy [19,27,28], C-section [29]), (4) gastrointestinal procedures (laparoscopy [30], colonoscopy [21], endoscopic retrograde cholangiopancreatography (ERCP) [20]) and (5) cardiac procedures (heart surgeries performed with cardiopulmonary bypass [22], cardiac implantable electronic devices implantation [23,31], cardiac ablation procedures of cardiac arrhythmias) [32][33][34]. Gas embolism has also been described in ophthalmological [35] and dental procedures [36].…”

“…Mechanisms for gas embolism differ widely among the specialties. For example, in cardiac surgery procedures, possible mechanisms are the entry of air into extracorporeal bypass pump circuit and incomplete removal of air from the heart following weaning from cardiopulmonary bypass [22]. In neurosurgery procedures, the possible mechanism of gas embolism is entry of air through incised veins and calvarial bone, especially during craniotomy with the patient in a sitting position.…”