Acquired Fontan Physiology Secondary to Acute Mechanical Tricuspid Valve Failure in a Patient With Massive Right Heart Enlargement and Ebstein’s Anomaly
A 25-year-old man with Ebstein’s anomaly and a secundum atrial septal defect had a mechanical tricuspid valve replacement (St. Jude 31-mm valve) and atrial septal defect closure when he was 15 years old. He was under long-term specialist follow-up and had recently been admitted with symptoms and signs of right heart failure secondary to new onset atrial flutter. He was direct-current cardioverted and commenced on ramipril and metoprolol. He then went to have an electrophysiological study and successful atrial flutter ablation.
At review 6 months later he reported good exercise tolerance and was now able to play 18 holes of golf, whereas previously he could only manage 9 holes. However, he commented that since the electrophysiological procedure he had been unable to hear his prosthetic valve clicks. On clinical examination he was not cyanosed, the jugular venous pressure was elevated at 4 cm without prominent V waves, there was a soft first heart sound, no audible mechanical valve clicks, and a pansystolic murmur. There were no signs of heart failure or peripheral edema. An electrocardiogram demonstrated sinus rhythm, right axis deviation, first-degree heart block, and right bundle-branch block with QRS duration of 200 ms. Echocardiography and fluoroscopy (Figure 1) showed that the leaflets of the St. Jude bileaflet tricuspid valve prosthesis were fixed in an open position with bidirectional flow (continuous wave Doppler trace, color Doppler of valve, and echo and fluoroscopy cine loops; see Figure I and Movies I–VI in the online-only Data Supplement). The right ventricle was severely dilated, dysfunctional, and essentially noncontractile. The left ventricle was normal in size with moderately reduced systolic function. Cardiovascular magnetic resonance imaging demonstrated a massive noncontractile right ventricle with an end diastolic volume of 1320 mLs with blood flow from the caval veins into the right atrium, through the open tricuspid valve replacement, into the right ventricle which essentially acted as a passive conduit and then into the pulmonary arteries (Figure 2; see Movie VII in the online-only Data Supplement).
This acquired “Fontan physiology” with passive nonpulsatile pulmonary blood flow was hemodynamically well tolerated, but in light of concerns about the development of malignant arrhythmias, he was admitted for implantation of an endocardial cardiodefibrillator. He was also referred for a heart transplant assessment because his long-term prognosis was uncertain. During the 12 months that he was on the heart transplant waiting list, he had no implantable cardiodefibrillator therapies and remained well, asymptomatic, and he continued to play golf.
In 1623 William Harvey described the circulation as needing “two ventricles of the heart, the right and left,” for each of the systemic and pulmonary circulations.1 However, it became recognized that pulmonary arterial pressures were low in some mammalians, with peak systolic pressures of 25 mm Hg and diastolic pressures of 10 mm Hg, implying that venous pressure may be of a sufficient force to drive pulmonary blood flow.2 Fontan et al3 applied this concept to the treatment of children born with tricuspid atresia. Now the total cavopulmonary connection is considered the most appropriate form of right heart bypass, with an end-side anastomosis of the superior vena cava onto the right pulmonary artery and inferior vena cava baffling to the main pulmonary artery, bypassing the need for a pulmonary ventricle.
In this patient the dilated, noncontractile right ventricle acted as a passive conduit for systemic venous return to the pulmonary artery after acute tricuspid valve replacement failure. Surprisingly his functional status improved, possibly because when functioning normally the mechanical tricuspid valve replacement offered resistance to flow, within the severely dilated and poorly functioning right heart, whereas when fixed open it offered minimal resistance, creating a Fontan-like physiology.4
All authors contributed to patient management and report preparation. Written consent to publish was obtained from the patient.
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.113.003089/-/DC1.
- © 2013 American Heart Association, Inc.
- Harvey W
- Rodbard S,
- Wagner D
- de Leval MR,
- Dubini G,
- Migliavacca F,
- Jalali H,
- Camporini G,
- Redington A,
- Pietrabissa R