Uhl anomaly

Key takeaways

Uhl anomaly belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Uhl anomaly to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Uhl anomaly from memory before moving on to harder problems.

Reference excerpt

Uhl anomaly is a rare cardiac malformation that was first identified by Dr. Henry Uhl in 1952. It is characterized by the absence of the right ventricle (RV) myocardium, either entirely or partially, and the replacement of the RV myocardium by nonfunctional fibroelastic tissue that resembles parchment. As of 2010 fewer than 100 cases have been reported in literature. Patients will typically present as infants with right-sided heart failure. Atrial right-to-left shunting is frequently observed as the cause of cyanosis. Typically, magnetic resonance imaging, computed tomography, and echocardiography are used to make the diagnosis.

Signs and symptoms Infants may exhibit severe cyanosis and right heart failure at birth, though these conditions may get better as pulmonary vascular resistance decreases. The main clinical features in older patients are right heart failure symptoms and signs.

Causes Although the precise cause of Uhl's anomaly is unknown, there have been reports of primary nondevelopment of myocytes, selective apoptosis, and cardiomyocyte overexpression of vascular endothelial growth factor. A sporadic mutation could indicate that genetics is the underlying cause.

Mechanism The pathophysiological outcome of Uhl anomaly involves compromised diastolic filling and right ventricular contraction. Systemic venous congestion and elevated right atrial and systemic venous pressure are the results of right ventricular failure. High pulmonary vascular resistance newborns may develop functional pulmonary atresia (a result of ineffective right ventricular forward flow). Cyanosis is caused by a right-to-left shunting of blood through the patent oval foramen.

Diagnosis Myocardial biopsies can confirm the diagnosis, which is often established by imaging tests like cardiac magnetic resonance imaging or echocardiogram. Right atrial and right ventricular dilatation is the cause of the cardiomegaly seen on the chest radiograph. The lung fields of newborns with functional pulmonary atresia and high pulmonary vascular resistance appear oligaemic. Right ventricular and right atrial dilatation is evident on the electrocardiogram. One can observe an epsilon (ε) wave in the right praecordial leads. An echocardiographic evaluation reveals a thin free wall of the right ventricle without any myocardium, reduced contractility and restricted ventricle filling, dilation of the right atrium, and normal tricuspid valve attachment to the right atrioventricular junction. Global dyskinesia of a thin-walled right ventricle, absence of myocardium at the right ventricular free wall, lack of fibrofatty infiltration, normal tricuspid valve attachment to the right atrioventricular junction, and normal left ventricular myocardium are all indicative of cardiac magnetic resonance imaging findings. Histopathologically, nonfunctioning fibroelastic tissue replaces the myocardial layer, giving the right ventricular free wall a parchment-like appearance. Other anomalies that can result in RV dilatation, such as Ebstein anomaly, RV arrhythmogenic dysplasia, pulmonary atresia, and anomalous pulmonary venous return, are included in the differential diagnosis of Uhl anomaly.

Treatment When the pulmonary vascular resistance has become high and the newborn has severe cyanosis soon after birth, a brief intravenous prostaglandin E infusion is recommended. In most cases, diuretics are necessary for congestive right heart failure. Various surgical techniques have been used, such as: (1) one-and-a-half ventricular repair alongside partial right ventriculectomy and bidirectional Glenn shunt; (2) right ventricular exclusion alongside atrial septectomy as well as a bidirectional Glenn shunt (superior cavopulmonary anastomosis); and (3) cardiac transplantation.

References

Further reading Agarwal, Rakesh; Datta, Rajarshi; Saha, Manjari; Sarkar, Nirmalendu (2016). "Uhl's anomaly: A rare case of portal hypertension". Heart Views. 17 (4). Medknow: 142–145. doi:10.4103/1995-705x.201779. ISSN 1995-705X. PMC 5363090. PMID 28400938. Faria, Bebiana; von Hafe, Pedro; Ferreira, Francisco Castro; Almeida, Filipa; Dias, Geraldo; Cardoso, Filipa; Lourenço, Mário Rui; Ribeiro, Sílvia; Lourenço, António (2020). "Uhl's Anomaly: 10 Years of Follow-Up of an Unoperated Patient". CASE. 4 (5). Elsevier BV: 351–355. doi:10.1016/j.case.2020.05.014. ISSN 2468-6441. PMC 7581623. PMID 33117927. Cardaropoli, D.; Russo, M. G.; Paladini, D.; Pisacane, C.; Caputo, S.; Giliberti, P.; Calabrò, R. (2006). "Prenatal echocardiography in a case of Uhl's anomaly". Ultrasound in Obstetrics & Gynecology. 27 (6): 713–714. doi:10.1002/uog.2798. ISSN 0960-7692. PMID 16710881.

External links

Illustrations

Worked examples

Example 1 — a first encounter with Uhl anomaly

Start with the simplest possible case. Write down what Uhl anomaly claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Uhl anomaly before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Uhl anomaly ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Uhl anomaly

In research: Uhl anomaly appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Uhl anomaly in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Uhl anomaly is common in secondary-school and first-year university syllabi. It links to neighbouring topics Congenital heart defects, Rare diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Uhl anomaly outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Uhl anomaly in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Uhl anomaly means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Uhl anomaly out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Uhl anomaly in simple terms?

Uhl anomaly is a rare cardiac malformation that was first identified by Dr. Henry Uhl in 1952.

Why does Uhl anomaly matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Uhl anomaly?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Uhl anomaly.