Related Experiment Videos
Divalent ions and myocardial function during cardiopulmonary by-pass (CPB). Changes of total calcium, ionized
Insights
During open-heart surgery, maintaining optimal ionized calcium (Ca++) levels is crucial for heart function. This study suggests low calcium levels during cardiopulmonary bypass may be beneficial, with supplementation recommended before full heart recovery.
Area of Science:
- Cardiovascular Surgery
- Anesthesiology
- Biochemistry
Background:
- Open-heart surgery often requires cardiopulmonary bypass (CPB).
- CPB involves managing blood chemistry, including calcium and magnesium levels.
- Maintaining appropriate electrolyte balance is critical for myocardial function during CPB.
Purpose of the Study:
- To investigate the effects of CPB on total calcium (Catot) and ionized calcium (Ca++) levels.
- To evaluate the impact of hemodilution and varying calcium concentrations in prime solutions on calcium levels during CPB.
- To compare magnesium levels during Mg-induced cardioplegia versus anoxic cardiac arrest.
Main Methods:
- Analysis of blood samples from 17 patients undergoing open-heart surgery with CPB.
- Assays for Catot, Ca++, magnesium, hemoglobin, total plasma proteins, and acid-base status.
- Patients divided into three groups to compare hemodilution, prime solution calcium concentration, and Mg-induced cardioplegia.
Main Results:
- Hemodilution during CPB significantly decreased Catot, while Ca++ remained relatively stable.
- Low calcium (2.8 mEq/l) in prime solutions led to subnormal Catot and Ca++ levels.
- Magnesium levels increased at perfusion onset, remained elevated, and normalized postoperatively.
Conclusions:
- Low plasma calcium levels may be advantageous during CPB due to their relationship with myocardial ATP breakdown during ischemia.
- Sufficient calcium substitution is recommended only at the end of CPB before the heart resumes full function.
- Careful monitoring and management of calcium and magnesium are essential during CPB.
Abstract:
In 17 patients who underwent openheart surgery with cardiopulmonary bypass using heparinized fresh blood for priming the heart-lung machine the following investigations were done: Blood samples taken at different periods of surgery were assayed for total calcium (Catot), ionized calcium (Ca++), magnesium (Mg), hemoglobin, total pasma proteins, and the acid-base-status. Considering the different kinds of cardiopulmonary bypass the patients were divided into three groups: In the first group the results ofsurgical procedure with and without hemodilution perfusion were compared. During hemodilution perfusion Catot decreased markedly whereas Ca++ remained nearly constant. In the second group the influence of different calcium concentrations of the prime solution on Catot and Ca was tested. A low calcium content of 2.8 mEq/1 lowered Catot and Ca++ to subnormal levels. In the third group results of Mg-induced cardioplegia were compared with findings during surgical procedure with anoxic cardiac arrest. A remarkable increase of magnesium at the perfusion onset could be observed. Magnesium remained within the upper level of normal range until surgery end and decreased to normal values in the postoperative stage. Since energy requirements of the arrested heart and thus the velocity of ATP-breakdown during ischemia are closely related to the Ca++ concentration of the extracellular space low plasma calcium levels are considered to be advantageous during cardiopulmonary bypass. Only at the end of partial bypass before the heart fully takes over circulating work a sufficient calcium substitution is recommended.