Cardiac Surgeon | Assistant Professor | @TexasChildrens | Visual insights in surgery, cardiology & intensive care | Views my own
Joined July 2025
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Left-to-Right vs Right-to-Left Shunting
👉Left-to-right shunts increase pulmonary blood flow and produce pulmonary overcirculation with volume loading of the involved chambers.
👉Right-to-left shunts bypass effective pulmonary oxygenation, causing systemic desaturation and reduced systemic oxygen delivery.
👉Shunt direction and magnitude depend on anatomy, pressure gradients, ventricular compliance, PVR/SVR balance, and pulmonary blood flow.
Aortic Valve & Root Anatomy #2: Root Configuration and Surrounding Structures
👉The aortic root comprises the sinuses of Valsalva, commissures, interleaflet triangles, and sinotubular junction.
👉The root is anchored within the cardiac fibrous skeleton, with aorto-mitral continuity and proximity to the membranous septum.
👉The aortic root lies adjacent to the pulmonary root, RVOT, and septal tricuspid annulus, reflecting its central anatomical position.
Fundamental Principles of Hemodynamics
👉Hagen–Poiseuille’s law describes flow resistance (Q ∝ r⁴), while Bernoulli’s principle explains pressure–velocity relationships across stenotic lesions.
👉Reynolds number predicts flow turbulence, while Laplace’s law relates pressure, chamber radius, and wall thickness to myocardial wall stress.
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Why can a tiny change in blood vessel diameter dramatically alter blood flow?
The Hagen–Poiseuille equation reveals the power of the fourth: double the vessel radius, and blood flow increases 16-fold, assuming all other factors remain constant!
A beautiful example of how physics explains vascular physiology — and why arterioles play such a crucial role in regulating tissue perfusion.
Fundamental Principles of Hemodynamics: Ohm’s Law & Laplace’s Law
👉Hemodynamic Ohm’s law defines flow as Q = ΔP/R : pressure gradient drives flow, while vascular resistance opposes it.
👉Laplace’s law relates wall stress as T = (P × r)/(2h) : stress rises with ↑P or ↑r and falls with ↑h.
👉Clinically, these principles frame SVR/PVR, ventricular pressure/volume overload, hypertrophy/dilation, etc
Fundamental Principles of Hemodynamics: Bernoulli, Poiseuille & Flow Regimes
👉Bernoulli’s principle links velocity and pressure: flow acceleration through stenosis lowers lateral pressure; Doppler uses ΔP ≈ 4V².
👉Hagen–Poiseuille’s law shows Q = πr⁴ΔP/(8μL), making vessel, shunt, conduit, or cannula radius a dominant determinant of flow.
👉Laminar flow is orderly; turbulence is favored by ↑velocity, ↑diameter, and ↓viscosity, increasing energy loss and abnormal wall shear stress.
Aortic Valve & Root Anatomy #1: Aortic Leaflet and Root Structures
👉The aortic valve has three semilunar leaflets: right coronary (RCC), left coronary (LCC), and non-coronary (NCC).
👉Each leaflet has a hinge line, body, free margin, lunula, and nodulus of Arantius, contributing to central coaptation.
👉The RCC and LCC are associated with the right and left sinuses of Valsalva, giving rise to the RCA and LCA, respectively.
Tricuspid Valve Anatomy and Ring Annuloplasty
👉Ring annuloplasty stabilizes the anterior and posterior annulus while avoiding the septal annulus to protect the AV conduction axis.
Surgeons in Japan aimed to characterize the segmental and mechanistic features of functional tricuspid annular dilatation using standardized intraoperative measurements in this recent #JTCVS study. Read more by logging in: hubs.la/Q04BqhQs0
Tricuspid Atresia: Surgical Palliation and Staged Fontan Circulation
👉Initial palliation balances Qp/Qs: PGE1, ductal stenting, or SP-shunt for low PBF; PA banding for excessive PBF.
👉In Type II TA, restrictive VSD/BVF causes subaortic obstruction, potentially requiring ASO, DKS, or Norwood-type repair.
👉The Glenn reduces ventricular volume load, while Fontan completion requires low PVR, adequate preload, and unobstructed pathways.
Pulmonary Atresia with Intact Ventricular Septum (PA-IVS)—Pulmonary and Coronary Circulation🫀
👉Pulmonary blood flow is initially ductal-dependent, and RV decompression may establish antegrade RV–PA flow; however, in RV-dependent coronary circulation (RVDCC), decompression can precipitate myocardial ischemia.
3-day-old, SpO2 50% on room air with respiratory distress
@AEPCcongenital
@escardio @ASE360 @iamritu @alexsfelixecho @CASivaram1 @loomba_rohit @alex1708ander @CardioNeo @argulian @sujithsp @SIwa23288585 @swatigar @cardiopedhnn
Tricuspid Atresia: Anatomy, Great Artery Relationships, and Hemodynamics
👉Tricuspid atresia lacks an RA–RV connection, making interatrial communication essential for systemic venous return.
👉Type I (NGA): The LV supplies systemic flow; pulmonary blood flow depends on VSD size, PS/PA, and ductal patency.
👉Type II (TGA): The LV ejects into the PA; systemic output depends on the VSD/BVF and RV outflow tract patency.
Cardiac Conduction Axis—Surgical Anatomy📖
👉The AV node continues as the penetrating His bundle through the central fibrous body, coursing along the inferior margin of the interventricular membranous septum before branching into the LBB and RBB.
👉The RBB emerges on the RV septal surface posterior to the muscle of Lancisi, an important anatomical landmark for avoiding conduction injury during VSD closure.
A new dimension in cardiac imaging: Three-dimensional exploration of the atrioventricular conduction axis with hierarchical phase-contrast tomography
heartrhythmjournal.com/artic…
Mitral Valve Replacement — Series: #1–3
👉MVR is indicated when durable repair is unlikely, requiring careful assessment of valve pathology and periannular anatomy.
👉Surgical strategy emphasizes subvalvular preservation, secure prosthesis positioning, and individualized valve selection based on durability and anticoagulation requirements.
↓ Full series below
3/3 | #3 Valve Selection and Anticoagulation
👉Mechanical valves offer long-term durability but require lifelong warfarin, whereas bioprosthetic valves avoid routine lifelong anticoagulation at the cost of structural degeneration.
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Mitral Valve Replacement #3: Valve Selection and Anticoagulation
👉Mechanical valves offer excellent durability but require lifelong warfarin anticoagulation, typically targeting an INR of 2.5–3.5.
👉Bioprosthetic valves generally avoid lifelong anticoagulation but carry a risk of structural degeneration and future reoperation.
2/3 | #2 Anatomy and Surgical Techniques
👉MVR requires precise knowledge of periannular structures, appropriate leaflet and subvalvular preservation, and secure prosthesis implantation.
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Mitral Valve Replacement #2: Anatomy and Surgical Techniques
👉Key periannular structures include the circumflex artery, coronary sinus, AV node, aortic valve, and right/left fibrous trigones.
👉Leaflet resection or preservation depends on anatomy; preserving the subvalvular apparatus helps maintain LV geometry and function.
👉An appropriately sized prosthesis is secured intra- or supra-annularly, with mechanical valve orientation optimized for leaflet motion.
1/3 | #1 Indications, Anatomy, and Prosthesis Selection
👉MVR is considered for irreparable mitral pathology, with prosthesis selection guided by valve anatomy, durability, and anticoagulation requirements.
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Mitral Valve Replacement #1: Indications, Anatomy, and Prosthesis Selection
👉MVR is considered when durable repair is unlikely due to severe prolapse, leaflet restriction, rheumatic disease, or calcification.
👉Mechanical valves offer durability but require lifelong anticoagulation; bioprosthetic valves carry degeneration and reoperation risks.
Fumiya Yoneyama, MD, PhD | WithAScalpel retweeted
Ross Procedure and Left Ventricular Rehabilitation📚
👉The Ross procedure restores LV outflow using a pulmonary autograft, while endocardial fibroelastosis (EFE) resection may improve LV compliance and diastolic function.
👉In 36 infants undergoing Ross/Ross-Konno procedures, operative and late survival were both 94%, with a median LVEF of 56.5% at follow-up.
Jacob KA, et al. J Thorac Cardiovasc Surg. 2026;172:1074–1082.e2.
doi.org/10.1016/j.jtcvs.2026…
Open access in #JTCVS: Left ventricular rehabilitation after Ross operation for critical aortic stenosis with endocardial fibroelastosis. Read how surgeons saw excellent survival and substantial LV recovery: hubs.la/Q04zQtkp0
Mitral Valve Replacement #3: Valve Selection and Anticoagulation
👉Mechanical valves offer excellent durability but require lifelong warfarin anticoagulation, typically targeting an INR of 2.5–3.5.
👉Bioprosthetic valves generally avoid lifelong anticoagulation but carry a risk of structural degeneration and future reoperation.
