P1500 Reptilian heart in a man

Abstract

Abstract 40 year old man admitted to hospital due to tachycardia episode. His normal ECG was consistent with RBBB with a QRS duration of 200msec. He had undergone a VSD operation when he was 6. He had a 3/6 systolic murmor . On TTE, there was a VSD patch and a residual tiny VSD with a L-R shunt. The maximum systolic gradient of VSD shunt was measured as 92mmHg .There was also moderate tricuspid regurgitation (TR) with a peak velocity of 5.1m/sec and estimated sPAP of 103mmHg. Considering the measured sPAP and the VSD shunt gradients, his systolic blood pressure (SBP)should approximately be equal to sum of those two ( 103+ 92 = 195mmHg). However his BP was 140/90mmHg.When we examined his heart for a possible explanation for this inconsistency, we noticed a systolic aliasing inside the RV with a maximum velocity of 3.1m/sec and systolic gradient of 38mmHg. However the chamber with lower pressure (P) was the one to which the VSD shunt was directed, and this chamber was in direct continuity with pulmonary artery. So to confirm the P in this chamber we also used pulmonary regurgitation flow and measured a peak diastolic velocity of 3.8m/sec, meaning a mean PAP of 60mmHg .Cardiac catheterization also confirmed a sPAP of 116mmHg and mPAP of 65mmHg. The systolic aortic P was 145mmHg and systolic LV P was 152mmHg. So the unexpectedly high gradient of VSD shunt was still a mystery for us. While searching the literature to explain this , we noticed that the patients’ heart was resembling the reptilian heart model. The reptilian heart has two atria and one ventricle with 3 segments seperated via muscular ridges. In our patients’ heart ,the small chamber with high P in the RV was the cavum venosum, the larger chamber of RV with VSD was the cavum pulmonale, and the left ventricle was the cavum arteriosum. (Fig) The reptilian hearts typically have noncompacted myocardium which was actually the case in our patient. The reptilian hearts also have unique conduction system with no AV node and His bundle, and slow depolarization of ventricle from left to right. When we performed EPS, we found that the patient had no AV node and His bundle. Bringing together all these findings, we conclude that the patient has a reptilian heart with all anatomical, electrical and physiological features. And the answer to the mystery of inconsistent P recordings was hidden in ECG. The RBBB with very long QRS duration causes a delay between contraction of ventricles resulting in a dynamic P gradient between ventricles. We demonstrated this dinamic bidirectional shunt on CW recording when we obtained a more optimal recording of the shunt flow.This case demonstrates us one more evidence of human evolution; arising from single cell and developing to fish, to reptiles and to mammals. The evolution takes place again and again during neonatal life. If there is an embryological arrest, as occured in our patient, we can easily see the clues of this amazing human evolution. Abstract P1500 Figure