FRCA Notes

Minimally Invasive Cardiac Surgery

This page is included on account of the BJA Education article on the topic, but may be deemed expendable behind more frequently occurring cardiac anaesthetic topics.

Resources

  • Minimally invasive cardiac surgery (MICS) describes cardiac surgery performed through small chest wall incisions, rather than a full sternotomy
  • A number of procedures are possible using the minimally invasive approaches, though they carry additional complications and aren't suitable for all patients
  • MICS, when compared to conventional open cardiac surgery, benefits from:
    • ↓ blood loss
    • ↓ post-operative pain
    • Earlier mobilisation
    • Shorter hospital stay

  • Although the surgical approach varies depending on the procedure, in general:
    • The majority require a thoracotomy of some description
    • May require one lung ventilation
    • Frequently requires intra-operative TOE
    • Often employs CPB, but with femoral vessel cannulation

  • The term minimally invasive mitral valve surgery encompasses a range of procedures on the atrioventricular valves and atria

    • Indications → Surgery
    Mitral regurgitation → valve repair/replacement [commonest]
    Tricuspid regurgitation → valve repair/replacement
    Atrial myxoma → resection
    ASD/PFO → closure

  • Performed via a right anterolateral VATS or mini-thoracotomy incision, thus necessitating one-lung ventilation and right lung collapse
  • No significant mortality difference between minimally invasive and conventional approaches, however are associated with faster recovery/discharge

Contraindications

Absolute Relative
Ascending aortic aneurysm >4cm Chest wall issues: pectus excavatum, trauma/rib fratures, morbid obesity
No defined sinotubular junction Redo surgery (but potentially beneficial)
Severe aortic regurgitation Severe mitral annular calcification
Any contraindication to TOE Pleural adhesions
Mobile aortic atheroma Aortic atheromatous plaques


Minimally invasive direct coronary artery bypass grafting (MIDCAB)

  • Access via left anterior mini-thoracotomy (or sometimes inferior mini-sternotomy)
  • Benefits from potentially avoiding CPB and cardioplegia if off-pump MIDCAB is performed
  • Associated with faster recovery times and shorter CICU stay
  • Only suitable for 1- or 2-vessel grafting in certain patients

Minimal access aortic valve replacement (mAVR)

  • Usually done under mini-sternotomy or right anterior mini-thoracotomy

    • Benefits of mAVR vs. open approach
    ↓ duration of mechanical ventilation
    ↓ incidence of bleeding and transfusion
    ↓ post-operative pain
    Fewer wound infections
    Shorter CICU stay
    Faster return to normal activity

  • No difference in mortality, bypass time, cross-clamp time or the incidence of major adverse events
  • May benefit those who are at higher risk from open surgical repair but not suitable for TAVI

AF ablation surgery

  • Surgical approach has a superior success rate of conversion to sinus rhythm than catheter ablation
  • Multiple surgical techniques exist:
    • Bilateral VATS incisions ± CPB technique
    • Combined surgical + percutaneous endocardial catheter ablation

  • Associated with a 93% rate of maintaining sinus rhythm at 12 months and a low risk of complications inc. mortality

Other minimally invasive approaches

  • Robotic-assisted cardiac surgery

Perioperative management of the patient undergoing minimally invasive mitral valve surgery


Patient selection

  • Elderly and/or frail patients are more likely to benefit from the minimally invasive approach
  • Those with significant aortic atheromatous disease and significant comorbidities may be unsuitable (see contra-indications, above)
  • Cosmetic benefits (vs. midline sternotomy) may be more appealing to younger patients

Assessment

  • Cardiovascular disease
    • Primary cardiac issue requiring surgery
    • Concomitant cardiovascular comorbidities
    • Functional capacity

  • Respiratory disease
    • May have history of chronic lung disease
    • Procedures performed via a thoracotomy often require one-lung ventilation
    • Formal assessment of respiratory function; higher risk of POPC if FEV1 or DLCO <40% predicted
    • Assessment of pulmonary vascular pressures e.g. on pre-operative TTE

  • Check for contra-indications to TOE, which is required in the majority of cases
    • Oesophageal disease inc. webs, strictures, neoplasms, lacerations, varices, achalasia, diverticulae
    • Gastric disease e.g. active PUD, hiatus hernia, previous surgery

  • Musculoskeletal disease which may complicate surgical access
    • Morbid obesity
    • Chest wall deformities inc. kyphoscoliosis
    • Small thoracic cavity

Investigations

  • Bloods inc G&XM
  • ECG
  • TTE ± TOE
  • Coronary angiography
  • Pulmonary function tests (in isolation or as part of functional assessments e.g. CPET)
  • CT angiogram to assess peripheral arteries and aorta for contra-indications (see above)

Monitoring and access

  • AAGBI
  • Temperature monitoring: bladder and nasopharyngeal probes to closely monitor core temperature during CPB
  • Arterial line; may need bilateral radial arterial cannulae if an endoballoon cross-clamp approach is used
  • CVC; check site choice with surgeons so as to not interfere with other planned cannulae

  • Depth of anaesthesia monitoring
  • Cerebral oximetry using NIRS if peripheral CPB is used
  • External defibrillation pads in situ as unable to provide internal defibrillation as in open surgery

  • Intra-operative TOE
    • Use is associated with reduced cardiovascular complications
    • Helps to exclude contraindicating pathologies prior to starting surgery e.g. ascending aortic dilatation, severe AR, extensive or mobile aortic atheroma
    • Facilitates assessment of the mitral valve, ventricular functions, PA pressures
    • Verifies positioning of CPB cannulae, endo-balloon ± additional lines

Anaesthetic technique

  • 'Cardiac GA', although some move towards reduced opioids to facilitate enhanced recovery
  • Endotracheal tube to facilitate one-lung ventilation i.e. DLT or single-lumen + bronchial blocker
  • TIVA or volatile maintenance acceptable
  • Meticulous approach to positioning, especially avoiding excessive traction on right arm brachial plexus with suitable padding of the arm

Analgesia

  • Paracetamol
  • Short-acting synthetic opioids + morphine
  • Regional techniques
Regional technique Notes
Local anaesthetic infiltration Simple
Thoracic epidural Higher risk of complications
Not suitable if needs anticoagulating
Debateably useful for fast-track patients
Paravertebral block/catheter Effective analgesia
Risk of non-compressible bleeding
Serratus anterior plane block Safer than paravertebral but inferior analgesia
Erector spinae block Superior analgesia to intercostal nerve block
Intercostal nerve block Inferior analgesia
Higher risk of LAST
Intrapleural infusion Continuous infusion may provide good analgesia
Catheter easily dislodges
PECS 1 & 2 blocks Little evidence for use in MICS

Surgical conduct

  • In many ways this is similar to standard cardiopulmonary bypass
  • Differences include:
    • CPB cannulation: femoral vein first, as opposed to aortic cannulation first in full sternotomy
    • Aortic cross-clamping options:
      • Trans-thoracic clamp (Chitwood clamp)
      • Endoballoon clamp via femoral artery cannula

  • Generally admitted to CICU but typically on fast-track ERAS protocols
  • May be extubated at the end of the case, or the DLT swapped for a single lumen tube and admitted to CICU intubated

Comparison to midline sternotomy

Reduced rates Comparable rates
Sternal complications Short-term & long-term mortality
Need for blood transfusion In-hospital renal, pulmonary & cardiac complications
Post-operative AF Pain
Duration of mechanical ventilation Re-admission rate
ICU & hospital length of stay

Specific MICS complications

  • Intra-operative
    • Occlusion of the innominate artery by endoballoon clamp (7%)
    • Conversion to sternotomy (1-3%)
      • Mostly for excessive bleeding
      • Other indications include pulmonary adhesions, aortic dissection or poor exposure of the mitral valve
      • Associated with a 30-day mortality of >20%

  • Post-operative bleeding; often from an intercostal vessel

  • Peripheral cannulation for CPB
    • Retrograde arterial perfusion associated with increased risk of neurological complications, stroke (2.1%) and aortic dissection (2%)
    • Femoral compartment syndrome
    • Femoral artery pseudoaneurysm (1 - 6%)

  • Nerve injuries
    • Right brachial plexus traction injury
    • Phrenic nerve injury (3%)
    • Standard risks of pressure-induced nerve injury at vulnerable sites e.g. ulnar nerve

  • Harlequin syndrome
    • A complication leading to poor oxygenation of the right cerebral hemisphere alone, leading to hemicerebral ischaemia
    • Due to incomplete emptying of the heart during establishment of CPB
    • There is consequent ejection of deoxygenated blood into the right brain, potentially at the same pressure as the retrograde oxygenated blood reaching the left brain
    • Prevented by ventilating the left lung with 100% oxygen until diastolic cardiac arrest

  • Complications associated with one-lung ventilation
    • Includes re-expansion pulmonary oedema (2.1%); associated with increased 30-day mortality