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Reviewed by: Dr. M. Rabinovitch
Congenital heart disease patients are prone to coronary artery disease similar to the rest of the population; however, these patients are prone to infarcts resulting from supply-demand imbalances that result from the natural history of their disease.We report the case of a patient with congenitally corrected transposition of the great arteries (ccTGA) with known coronary artery disease but with an infarct in an area remote from the myocardial distribution of the diseased coronary artery.
Case Report
The patient is a 47 year old male with known ccTGA who presented for a routine follow-up appointment at the adult Congenital Heart Disease (CHD) Clinic at Deborah Heart and Lung Hospital; Browns Mills, NJ in June 2001. His primary complaints were chest pain and shortness of breath. The patient's ccTGA is complicated by ventriculoseptal defect status post repair, and pulmonary stenosis status post two right ventricle to pulmonary artery conduits. In July 1999, he underwent cardiac catheterization for similar complaints of chest pain. Catheterization revealed a 40% stenosis of the circumflex artery. The other coronary arteries had no significant stenoses. Pulmonary pressures were within normal limits. Morphologic right ventricle (systemic) had an ejection fraction of approximately 45-50% with no left-sided atrioventricular regurgitation noted. Medical management was recommended at that time.
The patient did well for the next 16 months. He presented again for routine follow-up in CHD Clinic in November 2000. During this appointment, he complained again of three weeks of chest pain and related symptomatology consistent with unstable angina. An in-office ECG showed new, deep, symmetric T-wave inversions in the precordial leads. The patient was admitted to the hospital from CHD clinic with a diagnosis of unstable angina. Myocardial infarction was ruled out overnight by serial enzymes and troponin I results. He underwent repeat cardiac catheterization the following day, revealing a 95% lesion in the circumflex artery at the bifurcation of the second obtuse marginal artery. The other coronary arteries again had no significant stenoses. The morphologic right ventricle (systemic ventricle) had an ejection fraction of approximately 40%. The patient underwent percutaneous coronary intervention with stent of the lesion without complication. He was discharged home one day later in stable condition.
The patient did well for the next 7 months. In June 2001, he presented again to CHD Clinic for routine follow-up. He complained again of two to three months of intermittent chest pain, which was significantly different from his typical, anginal chest pain. Although the patient carries diagnoses of GERD and costrochondritis, given his history, a nuclear stress test was ordered to evaluate for new ischemic disease.
The patient underwent an exercise thallium stress test. He exercised for a total of 10 minutes on a Bruce protocol treadmill test. He achieved 3.4 mph at 14% grade, consistent with 9 METS of exercise. He achieved 81% of his maximum predicted heart rate. Heart rate response was normal. He experienced a transient decrease in his blood pressure and noted mild chest discomfort at peak exercise, both of which resolved promptly in the recovery phase. The ECG portion of the test was non-diagnostic due to baseline ECG abnormalities. However, pseudonormalization of anterior T waves occurred during exercise.
Immediate nuclear images were obtained in a 180-degree arc from a 45-degree RAO projection to a 45-degree LPO projection, using a dual headed Siemans e.cam SPECT camera with appropriate software to obtain gated images. Data were reconstructed in the short, horizontal long and vertical long axes (see figures 1 and 2).
In this patient the systemic ventricle is the morphologic right ventricle and the pulmonary ventricle is the morphologic left ventricle. The images revealed a small infarct in the apex of the systemic ventricle. This apical infarct persisted on rest, redistribution imaging with thallium re-injection. There was no peri-infarct ischemia. The gated images revealed paradoxical septal motion but all other segments contracted normally. The systemic ventricular ejection fraction was calculated at 56%.
Discussion
This case highlights the fact that adults with CHD disease are living longer and they are prone to the usual diseases that affict older adults including coronary artery disease. The intruiging point of this case is that the patient’s apical infarct in not in the distribution of the diseased coronary artery. Patients with ccTGA have a morphologic right ventricle that supplies the systemic circulation and a morphologic left ventricle that supplies the pulmonary circulation. These coronary arteries are switched as well. The right coronary artery distributes to a morphologic right ventricle. This right ventricle is sub-aortic and supplies the systemic circulation. The left main, circumflex, and anterior descending coronary arteries distribute to a morphologic left ventricle. This left ventricle is sub-pulmonic and supplies the pulmonary circulation. This patient's coronary stenosis was in the distal circumflex artery at the branch of the second obtuse marginal artery. The distribution of the diseased artery supplies the inferior-posterior wall of the morphologic left ventricle (pulmonary ventricle). However, this patient's infarct was at the apex of the morphologic right ventricle (systemic ventricle).
It is the last possibility that accounts for this patient's infarct. Perloff summarizes: "A relatively thin-walled morphologic right ventricle whose oxygen requirements are determined by the systemic vascular resistance is perfused by a concordant right coronary artery 'designed' by nature to perfuse a thin-walled, low-resistance morphologic right ventricle in the pulmonary location.3" The inverted morphologic right ventricle responds in a manner similar to that of a normal systemic left ventricle under analogous hemodynamic loads,3 i.e. hypertrophy.
There are case reports of patients with congenitally corrected transposition who present with symptoms of anginal chest pain and congestive heart failure. These patients have no history of hypertension and were found to have normal coronary arteries with a hypertrophied morphologic right ventricle,3 further supporting a supply-demand imbalance theory. Meaning, a right coronary artery that supplies a thick-walled morphologic right ventricle that, in turn, supports the systemic circulation.
In summary, patients with congenitally corrected transposition of the great arteries may live a normal lifespan. Thus, they carry the same risk for coronary artery disease similar to the rest of the population. However, they have an additional risk for infarction that results from the uniqueness of their condition. Morphologic right ventricular hypertrophy with inadequate coronary perfusion may create a supply-demand imbalance on the systemic ventricle. This is an important additional mechanism of infarction in this patient population.
References
1. Topol, EJ, ed., et al. Textbook of Cardiovascular Medicine. Philadelphia: Lippencott Williams and Wilkens; 1998: 787-788.
2. Braunwald E, ed., et al. Heart Disease A Textbook of Cardiovascular Medicine. Philadelphia: W.B. Saunders Co.; 1997:940-941.
3. Perloff, JK. The Clinical Recognition of Congenital Heart Disease. Philadelphia: W.B. Saunders Co.; 1994: 67-91, 747.
4. Hornung, TS et al. Right Ventricular Dysfunction in Congenitally Corrected Transposition of the Great Arteries. Am J. Cardiol. 1999;84:1116-1119.
5. Hornung, TS et al. Myocardial perfusion defects and associated systemic ventricular dysfunction in congenitally corrected transposition of the great arteries. Heart. 1998 Oct;80(4):322-6.