Effect of spinal anesthesia on the QT interval in term and post-term pregnancies scheduled for elective cesarean section: a prospective study

QTc Interval Changes in Preeclampsia vs. Normal Pregnancy: A Systematic Review and Meta-Analysis

Pregnancy induces significant adaptations in the cardio-autonomic nervous system, with additional cardiac stress in preeclampsia potentially impacting ventricular repolarization. Despite the widespread use of QT-prolonging drugs during pregnancy, the extent of heart rate (HR)-corrected QT (QTc) interval changes during normal pregnancy and preeclampsia remains unclear. This study aimed to quantify changes in QTc interval across different trimesters of normal pregnancy and third-trimester preeclampsia. Eight databases were systematically searched from their inception to January 13, 2025. Any type of study design, except case reports/series, reporting QT interval and HR or RR interval, and/or QTc interval for at least one trimester were included. Those reporting at least two trimesters or one trimester with nonpregnant controls were pooled in meta-analyses using random-effect models to calculate pooled mean differences (MD) across trimesters. Data from 57 studies (6,686 participants) were included with 33 studies (5,153 participants) pooled in meta-analyses. Compared with nonpregnant individuals, QTc intervals increased across trimesters of normal pregnancy and in third-trimester preeclampsia. Meta-analyses revealed significant increases in QTc interval during first (MD = 10.0 msec), second (MD = 20.2 msec), and third trimesters (MD = 23.0 msec) compared with nonpregnant individuals. Furthermore, preeclampsia increased the QTc interval by 21.7 msec during the third trimester compared to normal pregnancy. No publication bias was detected, and the overall quality scores of most studies were fair (n = 23) or poor (n = 33). A significant QTc interval lengthening throughout normal pregnancy was identified, and to a greater extent during preeclampsia. The arrhythmogenicity in third-trimester preeclampsia with a known risk for QTc interval prolongation, especially with using QT-prolonging drugs, warrants further investigation.

The Relationship between Body Mass Index and Frontal QRS-T Angle in Pregnant Women Undergoing Cesarean Section with Spinal Anesthesia

Background and objectives: The frontal QRS-T angle is a novel parameter of myocardial repolarization. Weight gain during pregnancy and physiological changes during a cesarian section may affect the frontal QRS-T angle. We aimed to assess the effect of body mass index (BMI) on the frontal QRS-T angle in pregnant women undergoing cesarean section with spinal anesthesia. Method and materials: This study included 90 pregnant women. BMI was calculated for all pregnant women. The study population was divided into two groups: BMI < 30 (n = 66) and BMI ≥ 30 (n = 24). QT interval measurements and the frontal QRS-T angle were obtained from the report of an electrocardiography machine. Results: It was found that the pre-operative and post-operative frontal QRS-T angle (p = 0.045 and p = 0.007) and QTc interval (p = 0.037 and p < 0.001) were higher in pregnant women with a BMI ≥ 30 than in pregnant women with a BMI < 30. In addition, when compared to pre-operative values, the post-operative frontal QRS-T angle (from 24.0 [20.0-41.5] to 34.5 [19.5-50.0], p = 0.031) and QTc interval (from 420.6 ± 13.3 to 431.7 ± 18.3, p = 0.010) were increased in the BMI ≥ 30 group, whereas no significant post-operative increase was observed in the BMI < 30 group. In correlation analysis, BMI was positively correlated with the frontal QRS-T angle and QTc interval. Conclusions: The frontal QRS-T angle and QTc interval were importantly increased in pregnant women with a BMI ≥ 30 than in pregnant women with a BMI < 30. Also, after cesarean section operation with spinal anesthesia, the frontal QRS-T angle and QTc were increased significantly in the BMI ≥ 30 group, whereas no significant change was observed in the BMI < 30 group. Therefore, it is suggested to perform close post-operative monitoring in pregnant women with a BMI ≥ 30 undergoing cesarean section with spinal anesthesia.

The relationship between gestational week and QT dispersion in cesarean section patients undergoing spinal anaesthesia: A prospective study

BACKGROUND

Pregnancy affects the cardiovascular system, particularly the cardiac conduction system, thereby increasing the susceptibility of patients towards arrhythmia. QT interval results in ventricular arrhythmias, predominantly polymorphic ventricular tachycardia. The present study was planned to investigate the relationship between a gestational week and QT dispersion in cesarean section patients undergoing spinal anaesthesia.

METHODS

The study included 40 patients between the ages of 18 and 45 who had no symptoms of anaemia and undergoing elective cesarean section. The patients were separated into two groups based on the gestational week as Group I <39 weeks and Group II ≥39 weeks. The patient was given a sitting position and the puncture site was cleansed with 10% povidone-iodine antiseptic solution. After placing a sterile drape on the patient, the subarachnoid space was punctured through an appropriate vertebral space (L3-L4 or L4-L5) using a pencil-point 25G spinal needle, followed by intrathecal injection of 12.5 mg (2.5 mL) 5% hyperbaric bupivacaine hydrochloride. Electrocardiographic (ECG) records were obtained both preoperatively and at 1, 5, and 10 minutes after spinal block, and the QT, QTc, QTd, and corrected QTd (QTcd) intervals were estimated using Bazett's formula.

RESULTS

There was no significant difference between the two groups within the QT and QTc intervals. QTcd measured after post-operative was significantly higher in Group II (P = .007).

CONCLUSION

The results indicated that spinal anaesthesia may prolong the QTdc interval in patients with a gestational week of ≥39 weeks undergoing cesarean section.

Comparison of nalbuphine, ondansetron and placebo for the prevention of shivering after spinal anaesthesia for urgent caesarean delivery: a randomised double-blind controlled clinical trial

BACKGROUND

Shivering is a common complication of caesarean delivery with neuraxial anaesthesia. The effective prevention and treatment of shivering, especially before delivery, is important and difficult. We tested the hypothesis that prophylactic nalbuphine and ondansetron can prevent post-spinal anaesthesia shivering in parturients undergoing urgent caesarean delivery.

METHODS

Sixty parturients scheduled for urgent caesarean delivery before spinal anaesthesia were selected and divided randomly into three groups. After peripheral venous catheterisation, parturients were given intravenous nalbuphine 0.08 mg/kg (group N), ondansetron 8 mg (group O), or normal saline (group C).

RESULTS

The incidence of shivering and of severe (grade ≥3) shivering was significantly lower in group N (15% and 15%, respectively) than in group C (80% and 65%) before delivery (P <0.001 and P=0.003); and significantly less shivering was observed in group N than in group C in the first 30 min after anaesthesia (P=0.001). Up to 60 min after anaesthesia, the incidence of grade ≥3 shivering remained lowest in group N (P=0.003). According to the data during the period from anaesthesia until delivery, the number needed-to-treat for nalbuphine was 1.54 (95%CI 1.13 to 2.41). No significant differences were found between groups O and N or groups O and C at any time. The incidence of dizziness in group N was significantly higher than that of groups O or C (P=0.009).

CONCLUSION

Nalbuphine 0.08 mg/kg can prevent post-spinal anaesthesia shivering in parturients undergoing urgent caesarean delivery but causes transient dizziness, while ondansetron 8 mg had no significant effect.