Cardiac cyanosis R23.0

The Lewis test was first described by Sir Thomas Lewis in 1933 (Lewis 1933).

Cardiac cyanosis is a bluish discoloration of the skin or mucous membranes due to mixing of venous and arterial blood (Herold 2023)

Cardiac cyanosis - together with pulmonary cyanosis - is one of the true central cyanoses. Cardiac cyanosis is a hemoglobin cyanosis (Herold 2023).

All congenital right-to-left shunts can lead to cardiac cyanosis. These heart defects include:

- Truncus arteriosus

- Tetralogy of Fallot (Menche 2020)

- Tricuspid atresia

- Transposition of the great arteries

- Pulmonary atresia

- Total pulmonary vein malformation (Herold 2023)

- Univentricular heart

- Aortic atresia

- Ebstein's anomaly

- Cor triatriatum (Hombach 2001)

The occurrence of an Eisenmenger reaction can also lead to cardiac cyanosis (Mewis 2006).

In central cyanosis, there is generally a reduction in O2 saturation in the arterial blood. In cardiac cyanosis, this is caused by the mixing of venous and arterial blood (Herold 2023).

Hemoglobin cyanosis occurs when the concentration of deoxygenated HB in the capillaries is > 5 g / dl (Herold 2023).

However, it should be noted that cyanosis appears earlier in erythrocytosis than in anemia. Cyanosis can no longer occur at Hb values of around 5 g / dl (Herold 2023).

The following symptoms are found in central cyanosis:

• Tongue and mucous membranes cyanotic (in contrast to peripheral cyanosis)
• Skin cyanotic
• Dyspnea (Herold 2023)
• Pathological cardiologic findings on auscultation

In the further course occur:

• Drum flail fingers
• watch glass nails (Mewis 2006)

Hypoxia test:

A so-called hyperoxia test is carried out to differentiate between cardiac or pulmonary central cyanosis. The patient is given 100 % oxygen for a few minutes. If this results in a reduction in cyanosis or a relevant increase in oxygen saturation, this is pulmonary central cyanosis.

In the case of cardiac-induced central cyanosis, however, the supply of pure oxygen does not lead to any improvement in oxygen saturation, as the oxygen supply cannot be improved by supplying oxygen in the case of a right-to-left shunt (Haas 2011).

- Lewis test:

The earlobe is compressed so strongly that it turns white. If the skin then immediately turns blue again, this is a case of central cyanosis. If the bluish discoloration only gradually returns, it is peripheral cyanosis (Mewis 2006).

- Echocardiography:

This is used to diagnose the cause of cardiac cyanosis (Haas 2011).

In the long term, central cyanosis occurs:

- Polyglobulia

The low arterial oxygen content leads to an increased release of erythropoietin in the kidneys. This in turn stimulates the bone marrow and more erythrocytes are formed. This enables the blood to bind more oxygen. However, as soon as the hematocrit rises above 65%, the viscosity of the blood decreases considerably, which has an unfavorable effect on peripheral circulation (Haas 2011)

- Drum flail fingers

- Watch glass nails

Chronic central cyanosis leads to the typical changes in the ends of the fingers and toes (Haas 2011).

The treatment of cardiac cyanosis consists of appropriate cardiac surgery (Mewis 2006)

1. Haas N A, Kleideiter U (2011) Pediatric cardiology: clinic and practice of heart disease in children, adolescents and young adults. II. leading symptoms: 10 cyanosis. Thieme Verlag Germany 79 - 80
2. Herold G et al. (2023) Internal medicine. Herold Publishers 153
3. Hombach V (2001) Interventional cardiology, angiology and cardiovascular surgery: technique - clinic - therapy. Schattauer Publishers Stuttgart / New York 576, 584
4. Kasper D L, Fauci A S, Hauser S L, Longo D L, Jameson J L, Loscalzo J et al. (2015) Harrison's Principles of Internal Medicine. Mc Graw Hill Education
5. Lewis T (1933) Diseases of the heart: described for practitioners and students. MacMillan London / New York 36 - 39
6. Menche N (2020) White series: internal medicine. Elsevier Urban and Fischer Publishers Germany 50 - 51
7. Mewis C, Riessen R, Spyridopoulos I (2006) Kardiologie compact: Alles für Station und Facharztprüfung. Georg Thieme Publishers Stuttgart / New York 8 - 9