Related Experiment Video
Updated: Aug 13, 2026
Continuous Manual Exchange Transfusion for Patients with Sickle Cell Disease: An Efficient Method to Avoid Iron Overload
Published on: March 14, 2017
Cardiovascular function during rest and exercise in patients with sickle-cell anemia and coexisting alpha
D S Braden1, W Covitz, P F Milner
1Department of Pediatric, University of Mississippi, Jackson, USA.
Insights
Sickle-cell anemia with alpha thalassemia-2 shows less anemia but increased cardiac wall thickness and abnormal diastolic filling. Exercise reveals higher heart rates and blood pressure, suggesting microvascular occlusion impacts cardiac function.
Area of Science:
- Cardiovascular Physiology
- Hematology
- Genetics
Background:
- Sickle-cell anemia (SS) is a genetic blood disorder associated with significant cardiovascular complications.
- Alpha thalassemia-2 is a genetic condition that can modify the severity of sickle-cell anemia.
- Understanding the combined effects of SS and alpha thalassemia-2 on cardiac function is crucial for patient management.
Purpose of the Study:
- To investigate cardiac function at rest and during exercise in patients with sickle-cell anemia and coexisting homozygous alpha thalassemia-2.
- To compare cardiac parameters between SS alpha thalassemia-2 patients, SS patients with normal alpha globin genes, and healthy controls.
- To elucidate the impact of coexisting alpha thalassemia-2 on the cardiovascular manifestations of sickle-cell anemia.
Main Methods:
- Cardiac function was assessed at rest and during exercise in 9 patients with SS and alpha thalassemia-2.
- Results were compared to 18 age-, gender-, and size-matched SS patients without alpha thalassemia and to published normal values.
- Echocardiography and Doppler indices were used to evaluate left ventricular dimensions, wall thickness, and diastolic filling patterns.
Main Results:
- SS alpha thalassemia-2 patients exhibited less anemia (9.9 g/dL vs. 8.2 g/dL) and normal left ventricular dimensions compared to SS patients.
- Significantly increased left ventricular wall thickness (free wall: 1.8 cm, septum: 1.6 cm) was observed in SS alpha thalassemia-2 patients.
- Abnormal resting diastolic filling (reduced early/late filling ratio) and increased heart rate/blood pressure during exercise were noted in SS alpha thalassemia-2 patients.
Conclusions:
- Coexisting alpha thalassemia-2 in sickle-cell anemia patients leads to distinct cardiac findings, including preserved ventricular dimensions but marked hypertrophy.
- Abnormal diastolic function at rest and altered hemodynamic responses during exercise suggest microvascular occlusion plays a role in cardiac pathology.
- The decreased hemoglobin in SS alpha thalassemia-2 may offer a protective effect against certain cardiovascular complications seen in sickle-cell anemia alone.
Abstract:
Cardiac function was measured at rest and during exercise in 9 patients with sickle-cell anemia (SS) and coexisting homozygous alpha thalassemia-2 (alpha thal-2). Results were compared with 18 sickle cell patients with normal alpha globin genes, who were matched to the study group by age, gender, and size, and to published normal values. SS alpha thal-2 patients were less anemic: 9.9 +/- 1.0 vs 8.2 +/- 1.2 gm/dl for SS alone (P<.05). Left ventricular dimensions were normal in SS alpha thal-2 (4.9 +/- 0.7 cm), but increased in SS (5.4 +/- 0.7, cm P=.05) (normal range, 3.7-5.6 cm). Left ventricular wall thickness was, however, dramatically increased in the SS alpha thal-2 patients (free wall, 1.8 +/- 0.6 cm; septum, 1.6 +/- 0.4 cm), though SS controls had normal wall thickness (free wall, 1.0 +/- 0.2 cm; septum, 1.0 +/- 0.2 cm, P<.001) (normal range, 0.6-1.1 cm). At rest, Doppler indices of systolic function were not significantly different between sickle groups and normal values. SS alpha thal-2 patients did have abnormal diastolic filling at rest, as evidenced by a reduced ratio of early/late diastolic filling, 1.4 +/- 0.3 vs. 2.0 +/- 0.5 for SS controls (P<.01), and 1.8 +/- 0.4 for normals. An analysis of covariance suggested that this abnormality persisted after taking into account the previously demonstrated hypertrophy. During exercise, SS alpha thal-2 patients had higher heart rates and blood pressures than SS controls in spite of performing the same or less work. This resulted in a higher double product (an estimate of oxygen consumption) in SS alpha thal-2 patients (37,470 +/- 2,310 mm Hg-BPM) than in SS controls (33,310 +/- 1,490 mm Hg-BPM, P<.01). Work capacity, peak heart rate, and blood pressure were all abnormally decreased in both sickle-cell groups when compared to normal. Cardiac abnormalities noted at rest and during exercise in SS alpha thal-2 patients suggest a role of microvascular occlusion and a protective effect of decreased hemoglobin.
Related Concept Videos
01:29Pathophysiology of Cardiac Performance
01:17Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be met...
01:26Imbalances in Cardiac Output
CHF can occur due to the failure of either side of the heart. Left-side failure leads to pulmonary congestion—the right side continues to send blood...
01:20Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
01:19Cardiac Output I:Effect of Heart Rate on Cardiac Output
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...
01:29Cardiovascular System Abnormal Findings I: Inspection and Palpation
Abnormal findings observed during an inspection