Cerebral flow pattern monitoring by transcranial Doppler during cardiopulmonary resuscitation.
Recently, minimally-invasive transcatheter aortic valve implantation has entered clinical routine in some specialised centres. This procedure can be performed either using an antegrade transapical approach or a retrograde transfemoral approach. In contrast to conventional aortic valve replacement, the calcium of the degenerated aortic valve is not resected. After a balloon-valvuloplasty, a valve-stent is anchored within the aortic annulus. To further assess the embolic load associated with this new procedure, we used TCD for study purposes.
We present a rare situation of real-time TCD monitoring during cardiopulmonary resuscitation (CPR) in a patient receiving transcatheter aortic valve implantation who sustained a cardiac arrest.
An 82-year-old female presented with a high surgical risk: logistic EuroSCORE 56.7% (European System for Cardiac Operative Risk Evaluation predicting 30-day mortality), 23.8% STS score (Society of Thoracic Surgeons Risk Score predicting 30-day mortality) and symptomatic aortic stenosis was admitted for off-pump minimally-invasive transapical aortic valve implantation. Prior to surgery she had two episodes of ventricular fibrillation requiring CPR. Magnetic resonance imaging showed only minor cerebral lesions and there was no obvious neurological deficit.
The operation was performed under general anaesthesia using sufentanil, propofol and rocuronium at induction and sevoflurane plus remifentanil for maintenance. Monitoring included left radial arterial blood pressure, right internal jugular central venous pressure, transoesophageal echocardiography and TCD (MultiDop X4 Digital, DWL Singen, Germany). The TCD-probe (multirange, multifrequency 2.0 MHz/2.5 MHz) was fitted to the patient's head using a hands-free head frame. At baseline (blood pressure 140/60 mmHg) the mean left middle cerebral artery flow velocity was 27 cm/s (Figure 1).
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Transapical aortic valve implantation was performed as described elsewhere (6). Unloading of the left ventricle was performed using rapid pacing at 150 beats/minute for a few seconds. The corresponding TCD flow profile is shown in Figure 2. Initial valve positioning appeared satisfactory. However, on deployment, due to low insertion and severe eccentric cusp calcification, occlusion of the left coronary artery occurred, with subsequent low-output syndrome and cardiac arrest requiring CPR. The deterioration of the TCD-flow pattern is demonstrated in Figure 3. Figure 4 shows the TCD-flow at the beginning of CPR with systolic peaks, but no diastolic flow pattern indicating suboptimal CPR. Accordingly, CPR was optimised by intravenous adrenaline, volume loading and by increasing the depth of external cardiac massage. This led to improved diastolic TCD-flow pattern (Figure 5). Cardiopulmonary bypass was established by femoral cannulation leading to a laminar TCD-flow profile (Figure 6). While much of the information related to ineffective CPR was obtained from haemodynamic measurements, the TCD profile provided additional information, and confirmed improved cerebral blood flow when more effective CPR was instituted.
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Mean middle cerebral artery flow velocity and mean arterial blood pressure are shown in Figure 7. The patient received two coronary artery bypass grafts (left anterior descending and first marginal) on the beating heart. After implantation of an intraaortic balloon pump, weaning from cardiopulmonary bypass was successful with moderate inotropic support. She was extubated and the intra-aortic balloon pump withdrawn on the first postoperative day. Further recovery was uneventful and without any neurological deficit.
Transcranial Doppler monitoring has been used to detect emboli occurring during cardiac surgery, in order to assess the impact of the embolic load on neurocognitive outcome (3). Newer generation TCD systems allow discrimination between gaseous and solid emboli (4). This type of information may be useful when assessing the effect of aortic manipulation in the context of cardiac surgery, particularly off-pump coronary artery bypass grafting (7).
In addition, TCD scanning allows monitoring of cerebral flow patterns. This has been clinically useful during potential cerebral malperfusion such as during hypothermic circulatory arrest, leading to an individual adjustment of flow (8). Another example is surgical therapy for aortic dissection requiring specific monitoring of cerebral perfusion (5). In such cases where selective antegrade cerebral perfusion has to be established, TCD might be of benefit.
In the case presented here, TCD monitoring was initiated to monitor the embolic load during transcatheter aortic valve implantation. However, the monitoring of cerebral flow patterns during cardiac arrest and CPR is a rare coincidence of clinical interest.
Generally CPR is guided by C[O.sub.2] values, the arterial blood pressure, pulse oximetry and central venous pressure. These indicators are often sufficient, but they do not provide an indication of cerebral blood flow. In this case, we feel that the TCD monitoring provided additional information during CPR, facilitating real-time assessment of cerebral flow during cardiac massage, and confirming effective treatment that would otherwise be guided only by standard indicators.
TCD might also facilitate monitoring of the actual cerebral flow according to the individual cerebral autoregulation. In the case presented here, the lower limit of cerebral autoregulation appeared to be at a mean arterial pressure value of approximately 60 mmHg.
This case demonstrates that TCD monitoring might be a useful clinical tool during operations where potential cerebral malperfusion can occur, such as complex aortic arch surgery involving circulatory arrest and selective antegrade brain perfusion.
Accepted for publication on September 11, 2009.
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(5.) Estrera AL, Garami Z, Miller C III, Sheinbaum R, Huynh TT, Porat EE et al. Cerebral monitoring with transcranial Doppler ultrasonography improves neurologic outcome during repairs of acute type A aortic dissection. J Thorac Cardiovasc Surg 2005; 129:277-285.
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(7.) Lev-Ran O, Braunstein R, Sharony R. No-touch aorta off-pump coronary surgery: the effect on stroke. J Thorac Cardiovasc Surg 2005; 129:307-313.
(8.) Estrera AL, Garami Z, Miller C III, Sheinbaum R, Huynh TTT, Porat EE et al. Evaluation of cerebral blood flow dynamics during retrograde cerebral perfusion using power M-mode transcranial Doppler. Ann Thorac Surg 2003; 76:704-709.
J. BLUMENSTEIN *, J. KEMPFERT [[dagger]], T. WALTHER [[double dagger]], A. van LINDEN [[section]], J. FASSL **, M. BORGER [[double dagger]], F. W. MOHR [[double dagger][double dagger]] Department of Cardiac Surgery and Anesthesiology, Heartcenter, Leipzig University, Leipzig, Germany
* M.D., Medical Student.
[[dagger]] M.D., Resident, Department of Cardiac Surgery.
[[double dagger]] M.D., Ph.D., Professor, Consultant, Department of Cardiac Surgery.
[[section]] M.D., Resident, Department of Cardiac Surgery.
** M.D., Assistant Professor, Anaesthetist, Department of Anesthesiology, Penn State College of Medicine, Pennsylvania, USA.
[[dagger][dagger]] M.D., Ph.D., Professor, Chairman, Department of Cardiac Surgery.
Address for correspondence: Dr J. Kempfert, Universitat Leipzig, Herzzentrum, Klinik fur Herzchirurgie, Struempellstr. 39, 04289 Leipzig, Germany. Email: firstname.lastname@example.org
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|Author:||Blumenstein, J.; Kempfert, J.; Waltherx, T.; van Linden, A.; Fassl, J.; Borger, M.; Mohr, F.W.|
|Publication:||Anaesthesia and Intensive Care|
|Article Type:||Case study|
|Date:||Mar 1, 2010|
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