European Journal of Cardiovascular Medicine

A complete heart block (CHB) or third-degree atrioventricular (AV) block occurs when atrial electrical activity fails to reach ventricular tissue, leading to an escape rhythm that generates ventricular contractions. The incidence of congenital complete heart block in the general population remains very low at about 1 in 20,000 newborns.

Pregnant women with complete heart block face significant challenges in their anaesthesia care due to the potential for severe bradycardia, hypotension, and fluid overload, which can result in uteroplacental insufficiency, particularly during delivery. The heart with abnormal conduction becomes more prone to sudden hemodynamic changes because of the physiological cardiovascular changes of pregnancy, which include increased blood volume, lower systemic vascular resistance, higher cardiac output, and hormonal influences. The heart rate response to stress is inadequate due to decreased variability in heart rate, which can lead to acute decompensation during anaesthetic induction or surgical stimulus.

The perioperative management of such patients involves arrhythmia control, urgent pacing requirements, and fluid balance management to prevent acute pulmonary edema or cardiac failure. Each case requires careful planning of prophylactic pacemaker or transcutaneous/transvenous pacing availability due to intrapartum bradyarrhythmias and poor cardiac reserve. These risks necessitate a multidisciplinary approach involving Obstetricians together with Anesthesiologistsand Cardiologists for the better outcome of both mother and baby.

A 20-year-old primigravida female at 37 weeks of pregnancy with a body weight of 52 kg and a height of 141 cm was referred from a district hospital with a history of congenital complete heart block and a permanent pacemaker implantation (PPI) that was later removed (this patient had a PPI implanted 2 years ago and removed because of infection two months post-PPI implantation).

The patient was admitted. The patient had no fresh complaints documented during the pre-anesthesia evaluation, and the patient had normal Complete Blood Count, Liver Function Test, Renal Function Test, Serum Electrolytes, Thyroid Function Test, and Prothrombin Time/International Normalized Ratio, and the ECG was suggestive of a complete third-degree heart block; the patient was hemodynamically stable with a fixed heart rate of 49-53 bpm with standard 2D echocardiography with an ejection fraction of 60% with no valvular anomalies with normal PASP noted; a cardiologist reference was done for the third-degree heart block, and standby support from the cardiology team was requested. The patient does not have complaints of dyspneaduring the whole pregnancy.

Nine days post-admission, the patient came to the OTComplex for an emergency LSCS due to Per-Vaginal Leaking; the patient was shifted to the OR Complex with a Foley catheter in situ. A well-written informed consent was taken for anaesthesia and surgery, and high-risk consent was taken before shifting the patient to OT. The consent forms were cross-checked by the Anaesthesiologist; NBM status was evaluated adequately, and the patient’s vital signs were within normal limits with a heart rate of 52 bpm.

The patient was taken inside the OT, and standard monitors like ECG, NIBP, and pulse oximeters were attached as per the standards, with a transcutaneous pacer attached on the right upper shoulder and left apex along with its own ECG leads, and the pacer was set to activate automatically at 50 bpm with 20 A current (Medicon Health Care, Model: Cardiomax Defibrillator with Monophasic Pacing Support). A wedge was placed in the right hip to provide the uterus with an upward tilt of 15–30° for IVC decompression by the gravid uterus. The patient had a 20G IV cannula on the right upper limb, a triple-lumen central venous catheter 7 Fr with USG guidance under local anaesthesia established in the left internal jugular vein, and another 20G IV cannula was established at the left upper limb, and an Inj. Ondansetron 4 mg and inj. Pantoprazole 40 mg were administered. Oxygen was provided with a face mask with 6 L O₂/min, and a single-shot Spinal anaesthesia was given in the sitting position with 0.5 % heavy levobupivacaine of 1.3 ml with 10 mg of injectable tramadol as an additive.

The patient was put in a supine position after administration of the drug, and complete dermatome anaesthesia of the T6 level was achieved when the patient complained of severe nausea. 5 minutes post spinal anaesthesia, an injection of 10 mg of metoclopramide was given slowly over 2 minutes. Adequate co-loading of 300 ml Ringer Lactate (RL) was given, and boluses of 50 ml to 100 ml RL were given during the episodes of hypotension, and it was augmented with inj. Mephentermine boluses of 3–6 mg through IV access. A set of cardiac drugs with loaded doses of inj. Phenylephrine 10 mcg/ml and inj. Isoprenaline 2 mcg/ml was kept for refractory hemodynamic changes. The patient maintained a stable heart rate of 51 bpm. The patient delivered a female child of 2.6 kg with APGAR scores of 8 and 9 at 1 minute and 5 minutes post-clamping and injection.

Inj. Pitocin 20 IU infusion was started after the cord clamping, and fluid management was tailored to the hypotension episodes of the patients with pharmacological intervention. The patient was auscultated consistently throughout the procedure to rule out the possibility of pulmonary edema, and the patient had an average urine output of 60 ml/hr. The procedure was completed, and the patient was observed in the recovery room postoperatively. The patient had a few sustained episodes of bradycardia, which were paced by a transcutaneous pacer. Eventually, the heart rate settled to 52 bpm until the spinal anaesthesia level receded to the level of motor blockade of Bromage-2.

The patient is then shifted to the Critical Care Unit for further management. The patient maintained hemodynamic status with a fixed heart rate of around 48 to 52 bpm. The patient was evaluated by a cardiologist with postoperative ECG and 2D echocardiography, which were within normal limits without any new pathological changes; the patient was then shifted to the ward after 24 hours of observation.

The care of a mother with congenital complete heart block during a lower segment cesarean section demands predicting quick changes in blood circulation while developing detailed intervention plans. Our main intervention consisted of co-loading instead of preloading. New research demonstrates that co-loading with crystalloid fluid administration during spinal block produces superior venous pooling control than preloading while preventing fluid overload and pulmonary edema. ¹. The delivery of injudious amount of fluids to patients with cardiac limitations or conduction disorders exposes them to severe adverse complications.

Our treatment plan used 0.5% heavy levobupivacaine combined with tramadol instead of bupivacaine. Levobupivacaine provides excellent sensory block effects together with reduced cardiotoxic effects, which are crucial for patients who have complete heart block because they are more vulnerable to myocardial depression. High-risk cardiac patients face a substantial increase in adverse cardiac events when cardiotoxic substances amount to even small levels².

The patient received a transcutaneous pacer because complete heart block presents an inherent risk of bradycardia, and spinal anaesthesia produces additional sympathetic blockade. The Medicon Health Care Model Cardiomax Defibrillator with Monophasic Pacing Support was programmed to activate automatically at a 50 bpm heart rate with a 20 A current. The automatic pacing mode quickly detected sudden bradycardia episodes while providing support to maintain hemodynamic stability. Medical research confirms that transcutaneous pacing should be initiated ahead of time for obstetric patients at high risk of fatal bradyarrhythmia after neuraxial anaesthesia,to meet conduction defects to ensure stable heart rates during bradycardia episodes in post-anaesthesia care units. ³

Auto-transfusion needed evaluation as a result of placental delivery. After placental delivery, the maternal circulation accepts blood that previously circulated in the uteroplacental area. The cardiovascular system responds to this sudden preload elevation by supporting cardiac output, but simultaneously experiences reflex bradycardia because of baroreceptor stretch. Natural autotransfusion and complete heart block together resulted in our patient developing protracted bradycardia after delivery and receiving fluids and medications. The autotransfusion process shows how hidden conduction defects become apparent, which requires ongoing pacing support until the autonomic functions normalise, according to the study⁴.

The fluid management requirements for this patient were optimised to the changing conditions of the case. The patient received 300 ml of Ringer Lactate through co-loading during spinal injection and needed additional boluses of 50-100 ml to manage hypotension and received titrated doses of Inj. Mephentermine (3-6 mg).  Inj. Phenylephrine and Inj. Isoprenaline remains prepared as emergency medications for unanticipated cases of refractory hypotension and bradycardia, which could endanger patient hemodynamic stability.⁵

The anaesthetic management plan combines co-loading with levobupivacaine while employing automatic transcutaneous pacing and fluid and vasopressor titration based on current evidence and clinical guidelines. The core management approaches work together to deliver optimal care for parturients with congenital complete heart block while improving both maternal and fetaloutcomes. The patient showed stable hemodynamic stability after the procedure with no new pathological ECG or echocardiographic findings.

The combination of precise anaesthesia procedures with active transcutaneous pacing and balanced cardiovascular control ensures proper and secure care for CHB patients undergoing LSCS. The successful transfer to ward care after 24 hours confirms the effectiveness of multidisciplinary care for maternal and fetal health.

Complete Heart Block in Non-Obstetric Surgeries: Anaesthesia Management and Overview

We would like to discuss anaesthetic considerations for patients with congenital complete heart block who are posted for non-obstetric surgeries with a brief overview on pre-operative pacing.

Preoperative Considerations

• Multidisciplinary Consultation:

Just like in obstetric cases, it is very important to have a Cardiology Consultation with adequate backup for further interventions. This is especially important in non-cardiac surgeries where the CHB may not have been the primary pathology. ⁶

• Risk Stratification:

Check for signs of decompensation or latent cardiac dysfunction. The initial management includes the correction of electrolytes as well as the correction of any other reversible causes of conduction delay (certain medications). ⁷

Intraoperative Management:

• Choice of Anaesthesia:

Regional anaesthesia may be used if systemic hemodynamic changes can be prevented or managed, depending on the type of surgical procedure and the patient’s general condition. However, if GA is needed, then necessary steps should be taken to manage the hemodynamic fluctuations. ⁸

• Monitoring and Hemodynamic Control:

Invasive monitoring with arterial lines and central venous lines may be required. The anaesthetic plan should be able to manage bradycardia and hypotension rapidly.

• Pacing Backup:

As a preemptive measure, a temporary pacer (transcutaneous or transvenous) should be arranged. This is especially true for patients with unstable conduction or those who have had previous episodes of decompensation. ⁹

Preoperative Pacing in Obstetric and Non-Obstetric Patients:

 Preoperative pacing, either through transcutaneous, transvenous, or permanent devices, is crucial in patients with conduction abnormalities to prevent perioperative hemodynamic instability. Since the physiology, urgency, and anaesthetic techniques differ, the decision and the method can be different between obstetric and non-obstetric patients.

1. Obstetric Patients
2. Physiological Considerations:

• Cardiovascular Changes during Pregnancy:

Pregnancy is associated with an increase in blood volume, cardiac output, and heart rate, but also a decrease in systemic vascular resistance. The above changes, coupled with the risk of quick hemodynamic changes with neuraxial anaesthesia (e.g., spinal blockade) and events such as placental delivery (autotransfusion), may unmask or worsen conduction disturbances.

• Fetal Well-Being:

The cardiac output of the mother is very important to maintain uteroplacental perfusion. Preoperative pacing can help in preventing maternal bradycardia episodes that could compromise fetal oxygenation, with the preservation of good uteroplacental flow. ¹⁰

1. Preoperative Pacing Strategy:

• Transcutaneous Pacing:

In some emergencies, TCP is often used as a temporary, non-invasive way to ensure a good rate and rhythm. It is preset to start at a certain heart rate (e.g., 50 bpm) during critical periods like neuraxial blockade or autotransfusion after placental delivery. ⁸

• Temporary Transvenous Pacing:

Temporary transvenous pacing may be considered in cases with more severe or symptomatic conduction defects. As the procedure is invasive, it is generally used for patients with persistent unstable hemodynamic status or when TCP cannot sustain a good heart rate, rhythm, and vitals. ¹¹

2. Non-Obstetric Patients
3. Physiological Considerations:

• Cardiac Comorbidities:

Non-obstetric patients with CHB or patients with other conduction disorders have different hemodynamic requirements. While these patients may not have the additional volume shifts seen in pregnancy, they often have a lower baseline heart rate and may be more prone to myocardial ischemia or decompensation under anaesthesia. ¹²

• Surgical Stress and Anaesthetic Agents:

General or regional anaesthesia can still trigger bradycardia or hypotension. In patients with severe conduction disorders, even a small drop in heart rate may be dangerous, especially if cardiac reserves are poor.

1. Preoperative Pacing Strategy:

• Permanent Pacemakers (PPM):

Many non-obstetric patients with significant conduction abnormalities already have permanent pacemakers implanted, and they are managed perioperatively to ensure that they are in the right mode (e.g., asynchronous pacing during surgery to prevent interference, with the availability of personnel from the pacemaker company to come for troubleshooting). ⁷

• Temporary Pacing Options:

 For patients without a PPM, preoperative temporary pacing (via TCP or transvenous pacing) is considered if the patient is at high risk for perioperative bradyarrhythmia. This is especially true in procedures where anaesthetic agents or surgical stimuli may worsen conduction delays. ¹³

How Preoperative Pacing Supports Anaesthetic Management

• Prevention of Hemodynamic Collapse:

 Preoperative pacing support in both obstetric and non-obstetric patients exists to navigate the episodes of bradycardia, which cause hypotension followed by cardiac output reduction and end-organ failure.

• Facilitating Safe Neuraxial or General Anaesthesia:

The safety measure of preoperative pacing enables anaesthesiologists to conduct regional anaesthesia for cesarean sections on obstetric patients by protecting them from spinal-induced bradycardia risks. General anaesthesia benefits from pacing since it controls anaesthetic agent depressant effects to maintain stable blood pressure during surgery.

• Evidence-Based Safety:

Preemptive pacing evidence demonstrates benefits for both patient populations through reduced perioperative complications. Medical research has established that detecting bradycardia early with pacing helps prevent severe hypotensive episodes that result in better outcomes for patients with conduction disorders. ¹⁴

Considerations for General Anaesthesia in Patients with Congenital Complete Heart Block:

The general anaesthetic management of congenital complete heart block patients demands a personalised approach through preoperative optimisation and drug selection with continuous monitoring and standby pacing capability. The main weakness of transcutaneous pacing includes possible complications that medical staff should evaluate against other pacing options. Patients with CHB who need non-obstetric surgery or develop decompensation must receive thorough evaluations by multiple specialists and receive close monitoring throughout their perioperative period to achieve the best results.

 The necessity for general anaesthesia (GA) exists in several specific situations regarding congenital complete heart block (CHB).

• Decompensated Patients:

The decompensated CHB patients cannot tolerate regional anaesthetic methods because of their symptomatic bradycardia and hypotension, along with heart failure. The general anaesthesia provides medical professionals with precise hemodynamic management through invasive monitors and immediate adjustments of vasoactive drugs. ¹⁵

• Contraindications to Neuraxial Techniques:

Some medical patients cannot undergo regional anaesthesia because of coagulopathy, together with infection at the injection site and patient refusal. The choice for patients is general anaesthesia.

• Complex or Prolonged Surgical Procedures:

General anaesthesia provides optimal control of both the airway and deep anaesthesia levels, which becomes vital for patients with heart conduction system problems. ¹⁶

• Need for Enhanced Monitoring and Interventional Readiness:

General anaesthesia enables patients to receive invasive monitoring equipment more effectively because it allows better implementation of devices such as arterial and central venous and transesophageal echocardiography. ¹⁷

• Patient-Specific Factors:

Additional medical conditions that include severe systemic diseases might prevent the use of regional anaesthesia in some CHB patients, thus necessitating general anaesthesia. ¹⁸

General Anaesthesia Management in Patients with CHB

This article provides an in-depth examination of general anaesthesia (GA) treatment protocols for patients with congenital complete heart block (CHB), as well as the limitations and complications related to transcutaneous pacing and standard management strategies for CHB patients having non-obstetric surgeries and decompression protocols.

Preoperative Evaluation and Optimisation

• Detailed History and Workup:

The complete history requires patients to share their previous syncope episodes alongside their exercise tolerance and any cardiac-related symptoms. Medical evaluations utilising ECG and echocardiography, together with Holter monitoring, help determine block severity and ventricular function. ¹⁹

• Cardiology Consultation and Pacing Strategy:

Cardiologist involvement remains essential because of the risk of hemodynamic instability. The decision to implant a temporary pacemaker through transvenous or external methods before surgery may occur during elective surgical procedures. ²⁰

Induction and Maintenance

1. Choice of Induction Agents:

The preferred induction agents in this case are etomidate because they cause minimal depression of the cardiovascular system. Propofol is widely used, yet its use results in substantial blood pressure drops, which doctors should administer with caution.²¹

Opioids are often used to blunt autonomic responses, but their dosing should be carefully titrated. ²¹

2. Airway Management:

The airway needs to be secured as a priority. If there is a risk of aspiration, then rapid sequence induction should be performed, especially in emergencies.

3. Hemodynamic Monitoring:

Arterial blood pressure monitoring is commonly used as an invasive procedure, and this enables the monitoring of blood pressure on a beat-to-beat basis and stroke volume variations and fluid therapy. Central venous access may help administer inotropes or fluids.

4. Maintenance of Cardiac Output:

During GA, an appropriate heart rate and myocardial contractility should be maintained. This often involves using vasoactive agents such as isoproterenol, dopamine, or norepinephrine, tailored to maintain perfusion pressure and support conduction if needed. ²²

5. Avoidance of Drugs that Exacerbate Bradycardia:

Medications that further slow the heart rate (e.g., high doses of beta-blockers) or reduce myocardial function should be avoided or used with extreme caution. ²³

Intraoperative Considerations

• Pacing Backup:

Although patients with CHB are under general anaesthesia, they may suddenly need pacing. Thus, it is crucial to ensure that a transcutaneous or temporary transvenous pacing setup is readily available. 8.11

Fluid Management:

Both volume depletion and fluid overload should be avoided. Meticulous fluid management helps to maintain preload without increasing the heart failure or the development of pulmonary edema. ¹⁶

• Anaesthetic Depth and Sympathetic Tone:

The anaesthetic depth should be carefully adjusted to prevent sympathetic overactivity that could lead to worsening conduction and hypotension due to excessive vasodilation. ²⁴

Management of CHB with Decompensations:

Recognizing Decompensation

Signs of cardiac decompensation are present through patient symptoms, including syncope and hypotension and heart failure indicators, and decreased exercise capacity. The following red flags include laboratory results, together with imaging data and hemodynamic instability. ²⁵

1. Preoperative Optimisation:

       The stabilisation process for patients with decompensated conditions takes priority before surgery. This may involve

• The treatment includes optimisation through inotropic medication administration.
• The use of diuretics should start when fluid overload occurs.
• The patient needs proper management of their electrolyte levels.
• Early implantation of permanent or temporary pacing devices should be considered for patients.²⁶

1. Intraoperative Management in Decompensated Patients

• Enhanced Monitoring:

A higher level of aggressive invasive patient monitoring is recommended. The real-time assessment of ventricular function should use continuous transesophageal echocardiography (TEE).²⁷

• Tailored Anaesthetic Regimen:

Select medications that produce the least amount of myocardial depression among available options. Medical staff need to administer medication slowly while checking hemodynamic parameters repeatedly.

• Readiness for Rapid Intervention:

Every resuscitation device and vasoactive medication needs to be easily accessible because patients may experience unexpected deterioration. The anaesthesiologist must establish an explicit pacing method, transition protocol, and advanced cardiac life support initiation procedure for specific scenarios.²⁸

Critical Care Management:

1. Initial Stabilisation & Monitoring

• ECG monitoring through a continuous system allows medical staff to detect both pauses and ventricular escape rhythms.
• Invasive Hemodynamic Monitoring: Arterial line for beat-to-beat blood pressure.
• A transcutaneous pacer should be used as a backup system with pacer pads ready for application.

2. Pharmacologic Support

First-Line Agents:

• Inj. Isoprenaline (Beta-1 agonist):
• The recommended IV infusion dosage of Inj. Isoprenaline ranges from 2–10 mcg/min.
• Advantages: Increases heart rate and contractility.

• Inj. Epinephrine (if hypotensive):

- Dose: 2–10 mcg/min (increased alpha 1 and beta 1 and beta 2 activity) ²⁹

3. Temporary Pacing

• Transcutaneous Pacer:

The immediate solution requires replacement, but it produces discomfort and lacks reliability for sustained treatment.

• Transvenous Pacer:

The preferred choice for patients requiring extended treatment of instability. ³⁰

4. Permanent Pacemaker Indications

• Patients who experience symptoms of CHB (syncope, heart failure) qualify for this treatment.
• Patients who remain asymptomatic yet display these conditions:
• A ventricular rate below 40 beats per minute.
• QRS > 120 ms²⁸

5. Post-Stabilisation Care

• Continuous for ≥72 hrs ³¹

Electrolyte Management:

• K+ > 4.0 mEq/L, Mg2+ > 2.0 mg/dL ³²

We highlight the anaesthetic management of a patient with a congenital complete heart block undergoing a lower-segment cesarean section (LSCS) in pregnancy under Spinal Anaesthesia, we emphasise the usage of transcutaneous pacing support in case of an emergency which proved essential for mitigating prolonged bradyarrhythmia, co-loading over preloading in reducing hypotension without increasing the risk of fluid overload, an especially important consideration for patients with impaired cardiac conduction.

The case shows the need for individualisation of patients posted for emergency or planned surgery with a coordinated multidisciplinary approach, hemodynamic management, close monitoring and care to achieve optimal results for the mother and the baby.

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