Show notes
CardioNerds (Amit Goyal & Daniel Ambinder) join Stanford cardiology fellows (Pablo Sanchez, Natalie Tapaskar, Jimmy Tooley) for tacos while enjoying the sunshine on the Stanford Oval! They recount the story of a man with adult congenital heart disease (ACHD): L-TGA (levo-transposed great arteries) with double inlet LV post-Fontan complicated by VF arrest. Dr. Christiane Haeffele provides the E-CPR and program director Dr. Joshua Knowles provides a message for applicants. Episode notes were developed by Johns Hopkins internal medicine resident Evelyn Song with mentorship from University of Maryland cardiology fellow Karan Desai and Cleveland clinic cardiology fellow Josh Saef.
Jump to: Patient summary - Case media - Case teaching - References
The CardioNerds Cardiology Case Reports series shines light on the hidden curriculum of medical storytelling. We learn together while discussing fascinating cases in this fun, engaging, and educational format. Each episode ends with an “Expert CardioNerd Perspectives & Review” (E-CPR) for a nuanced teaching from a content expert. We truly believe that hearing about a patient is the singular theme that unifies everyone at every level, from the student to the professor emeritus.
We are teaming up with the ACC FIT Section to use the #CNCR episodes to showcase CV education across the country in the era of virtual recruitment. As part of the recruitment series, each episode features fellows from a given program discussing and teaching about an interesting case as well as sharing what makes their hearts flutter about their fellowship training. The case discussion is followed by both an E-CPR segment and a message from the program director.
CardioNerds Case Reports PageCardioNerds Episode PageCardioNerds AcademySubscribe to our newsletter- The HeartbeatSupport our educational mission by becoming a Patron!Cardiology Programs Twitter Group created by Dr. Nosheen Reza
Patient Summary
A man in his mid-30s with past medical history notable for L-TGA (levo-transposed great arteries) with double inlet LV s/p Fontan palliation was playing golf when he suddenly collapsed. EMS arrived after three minutes of bystander CPR. An AED indicated the patient had suffered a VF arrest. ROSC was achieved after 1 round of Epi and 1 shock delivered. He was intubated and started on targeted temperature management protocol. Home medications were notable for digoxin 0.25mg daily, sotalol 120mg BID, and warfarin 5mg daily. Initial labs were notable for Na 127, K 5.4, Cr 1.0 (unknown baseline), INR 4.5, Lactate 4.6, Troponin-I 0.532, VBG 7.06/61, and random Digoxin level 2.7. EKG showed AV sequential pacing at a rate of 70 bpm. QTc prolonged at 571ms. No ischemic ST changes. Device interrogation showed sustained VT for 5 minutes prior to external shock. No internal shock was delivered. He was initially stabilized and his acidosis and hyperkalemia were corrected. Course was complicated by hemoptysis due to alveolar hemorrhagic and he was given concentrated prothrombin complex to reverse his coagulopathy. He eventually stabilized, and a formal TTE was obtained which showed a hypoplastic RV, single dilated LV with an akinetic posterior wall and hypokinetic lateral wall, all similar to his prior TTE in 2019. No obstruction noted at the IVC/Fontan anastomotic site. Coronary angiogram performed after his kidney function improved also did not show any significant obstructions or coronary anomalies. After multidisciplinary discussion, his VF arrest was attributed to a combination of prior ventricular fibrosis/scar, suspected digoxin toxicity, sotalol, dehydration, and renal failure. He had a subcutaneous ICD lead placed and was ultimately discharged home.
Case Media
ABClick to Enlarge
A. CXRB. ECG
Episode Schematics & Teaching
The CardioNerds 5! – 5 major takeaways from the #CNCR case
What's Transposition of the Great Arteries (TGA)? TGA is defined by a nontraditional ventricle-arterial relationship so that the aorta arises from the morphological RV and the pulmonary artery (PA) arises from the morphological LV There are two types of TGA, L or levo and D or dextro. D (rightward)-TGA: Systemic venous return flows into RA - RV - delivered to systemic circulation via Aorta, bypassing the lungs. The pulmonary veins flow into the LA - LV- delivered to the pulmonary circulation via the PA. The result is two parallel systems that fail to deliver oxygenated blood to the systemic circulation. This is not compatible with life unless another defect such as ASD, VSD, or PDA is present (or created) to allow mixing of deoxygenated and oxygenated blood. Patients with D-TGA usually require arterial switch procedures within 1 month of life. A simplified way to understand this is to say that the great vessels are malpositioned, leaving patients with two parallel circulation. L (leftward)-TGA: Deoxygenated blood flows into RA - morphologic LV in the traditional RV position - PA - Lungs- LA - morphologic RV in the traditional LV position - aorta to deliver oxygenated blood to the body. A simplified way to understand this is to say that the ventricles are malpositioned, leaving patients with two circulations in series (normal) with the pumps in the wrong places. There's no cyanosis at birth and patients may be completely asymptomatic for years. This is more rare than D-TGA and only occurs in ~7 per 100,000 births. The problem in L-TGA is that the morphologic RV, being the systemic ventricle, is not meant to withstand systemic afterload and can result in significant TR and ventricular dysfunction. Additionally, the majority of the cases (80%) are associated with an additional heart defect, such as VSD, pulmonary stenosis, RV hypoplasia, or DILV as in our case. What's Double Inlet Left Ventricle (DILV)? In DILV, both atrio-ventricular valves (mitral and tricuspid) lead into the LV and a large VSD is present to connect the LV and RV. DILV is very rare (~5 in 100,000 births). It coexists with L-TGA in about 65% of the cases. DILV leads to mixing of oxygenated and deoxygenated blood in the LV, resulting in inadequately oxygenated blood entering the systemic circulation and also over-circulation to the pulmonary system (increased Qp:Qs), resulting in LV congestion and heart failure over time. What's the Fontan procedure? The Fontan procedure is typically performed as a palliation procedure to direct flow of systemic venous return to the lungs without passing through a subpulmonic ventricle. It's typically performed in patients with complex congenital heart disease with a single functioning ventricle such as tricuspid atresia, pulmonary atresia, hypoplastic left heart syndrome, and DILV. In these conditions, intracardiac mixing of oxygenated and deoxygenated blood leads to cyanosis and ventricular volume overload without surgical intervention. The early variation of the Fontan procedure connected the pulmonary arteries to the RA. However, this led to RA dilation and loss of contractility, resulting in decreased pulmonary blood flow and increased risk for thrombus formation and arrhythmias. More modern Fontan palliation procedures connect both vena cavae directly to pulmonary arteries (via an intra- or extra-cardiac conduit), bypassing the RA and RV completely. Elevated pulmonary pressure is an absolute contraindication for the Fontan procedure since there's no ventricular contraction to pump blood through the lungs (it relies on passive flow). Therefore, the cavopulmonary Fontan circulation can't be created at birth given the normal high pulmonary vascular resistance in newborns. The modern Fontan palliation sequence is performed in a staged fashion to allow the patient's body to adapt to the different hemodynamic states and reduce overall surgical morbidity and mortality. Stage 1: systemic-pulmonary shunt; performed during neonatal period An artificial shunt is placed between a major systemic central vessel, usually subclavian artery, and proximal pulmonary artery. The goal of this step is to provide dedicated pulmonary blood flow to allow adequate oxygen delivery to tissues and pulmonary arterial growth. Stage 2: superior cavopulmonary connection (Glenn procedure); performed between 4-12 months Anastomosis is made between the SVC and proximal right PA. The previous systemic-pulmonary shunt is usually ligated. This allows priming of the pulmonary vasculature over time before completion of the Fontan circulation. Stage 3: completion of the Fontan circulation; performed between ages 1-5. Different surgical techniques are used, but the common endpoint is IVC anastomosis to the right PA. After the Fontan procedure, cardiac output is completely dependent on passive flow into the lungs. LV preload is central to Fontan physiology. Dehydration, an increase in pulmonary vascular resistance and/or worsening LV stiffness (and hence LV filling) can lead to decreased cardiac output. What are some complications associated with the Fontan procedure? RA dilatation was very common with the classic Fontan where atriopulmonary instead of cavopulmonary Fontan circulation was created, the RA is exposed to elevated pressure, leading to RA dilatation, thrombus formation, and arrhythmias. Ventricular failure usually develops after the first decade following completetion of the Fontan palliation. Patients will typically develop the classic symptoms of heart failure due to either HFrEF or HFpEF. Potential contributors to CHF include atrial tachycardia, valvular regurgitation, and volume-loading shunts. Atrioventricular valve (AVV) regurgitation can develop insidiously after the Fontan procedure and is a significant risk factor for long-term mortality post Fontan. AVV regurgitation can lead to volume overload, ventricular dilation, reduced ventricular contractility, and increased postcapillary and central venous pressures, compromising the Fontan circulation.