How to cite this article: Gadhinglajkar S, Sreedhar R, Jayant A. Pulsus alternans after aortic valve replacement: Intraoperative recognition and role of TEE. Ann Card Anaesth 2010;13:181-4
How to cite this URL: Gadhinglajkar S, Sreedhar R, Jayant A. Pulsus alternans after aortic valve replacement: Intraoperative recognition and role of TEE. Ann Card Anaesth [serial online] 2010 [cited 2022 May 21];13:181-4. Available from: https://www.annals.in/text.asp?2010/13/2/181/62932
Pulsus alternans (P ALT ) is beat-to-beat variability in systolic blood pressure, which occurs due to alternating stroke volumes of left ventricle (LV). It is known to be associated with severe left ventricular dysfunction., Although a large number of factors have been implicated in induction of PALT in the intraoperative period, it has not been reported to occur as a result of cardiac handling after aortic valve replacement (AVR). A 33-year-old male patient was operated for AVR on cardiopulmonary bypass (CPB). Preoperative transthoracic echocardiography (TTE) revealed a dilated left ventricle and severe aortic regurgitation (AR) with left ventricular ejection fraction of 25%. After establishment of CPB and cardioplegic arrest, the native aortic valve was excised and replaced with a 23-mm bileaflet prosthetic valve (St. Jude Medical, USA). The patient was weaned from CPB using 0.1 mcg/ kg/ minute of epinephrine infusion. A stable hemodynamic condition was maintained in the period immediately after weaning. TEE examination revealed a global LV hypocontractility with the left ventricular fractional area change of 24% [video 1]- . The AV prosthesis worked satisfactorily without any evidence of a paravalvular leak [video 2]- . As the heart rate decreased to 60/ minute from 84/ minute after cardiac decannulation, atrial pacing (AAI) was started at a rate of 90/ minute. When the surgeon started retracting the heart during surgical hemostasis, the systolic BP decreased from 120 mmHg to 70 mmHg. When the heart manipulations ceased, the PALT was observed on the monitoring screen with a systolic pressure difference of 30 mmHg between two consecutive beats [Figure 1], which lasted for about two minutes. The continuous wave Doppler (CWD) tracing recorded across the prosthetic valve in deep transgastric long axis (DTG-LAX) view revealed velocity time integrals (VTI)s of large and small sizes alternating with each other [Figure 2]C, 3 pulsus alternans. A regular pulse trace appeared with similar paced rhythm after two minutes, which was accompanied with a regular systolic ejection [Figure 2]A. We also observed a transient increase followed by a progressive decrease in the size of VTIs during positive pressure breathing, when the left atrial pressure was 3 mmHg [Figure 2]B. The surgeon was requested to minimize the phenomenon of alternans as it was seen repeatedly on cardiac manipulation. The alternans did not occur after the closure of sternum. Tracheal extubation was carried postoperatively after six hours of elective ventilation. His postoperative recovery was uneventful.
We viewed the AV CWD profile off-line and measured RR intervals and atrial pacing signal-to-R wave intervals on ECG, which remained constant during successive cardiac cycles of regular beats and beats during PALT [Figure 3],[Figure 4]. CWD cardiac cycle for a beat was considered as interval between onsets of systolic ejection of that beat and the next beat. The duration of CWD cardiac cycles also was constant for regular and PALT beats. The systolic ejection phase lasted longer in the bigger beat of PALT than the smaller one. On the contrary, the remaining cardiac cycle interval was longer for the smaller beat than the larger beat [Figure 4]. Characteristically, the period between the AV prosthetic end-systolic excursion preceding and following a large beat was longer than that between a smaller beat. Their addition, however, was equal to the summation of the period over two consecutive cardiac cycles [Figure 3]B. The Doppler intervals of different beats are summarized in [Table 1].
Intraoperative transaortic Doppler profile characteristics of PALT are rarely described in the literature. Contractile and hemodynamic mechanisms have been proposed to explain the phenomenon of the PALT., The contractile mechanism refers to incomplete recovery of contractile cells, leading to an alternating force of left ventricular contraction. The hemodynamic theory  is based on three factors affecting preloading conditions or left ventricular end-diastolic volume (LVEDV):
Duration of the diastole: The diastolic filling time of consecutive beats determines the end-diastolic volume. As the diastolic interval preceding a smaller beat is short, the resultant LVEDV would be lesser than that of a larger beat, which succeeds a longer diastolic interval. If the diastolic interval is short, the volume will be less and the beat will be smaller than the beat following a longer diastolic time interval.
Left ventricular residual volume: The residual volume at the end-systole contributes to the left ventricular filling for the next beat. The end-systolic volume affects the end-diastolic volume of the following cardiac cycle. A forceful contraction during a large beat facilitates emptying of the ventricle and reduces the contribution of residual volume to the left ventricular filling preceding a smaller beat.
Impaired left ventricular diastolic compliance: Inadequate recovery of the left ventricular myocardium after a large beat decreases the diastolic filling before the small beat. We observed that duration of systolic ejection phase was more during a larger beat than a small beat of PALT. Remaining portion of the cardiac cycle, which was constituted by the isovolemic relaxation phase, diastolic phase and isovolemic contraction phase, was shortened following a large beat. Characteristically, the period between the two consecutive prosthetic valve end-systolic excursions was varying alternately during PALT. It occurred because the smaller beat was preceded by a short filling interval, which was opposite for the larger beat.
The PALT is considered a marker of poor prognosis in a failing heart. Appearance of PALT in a heart with poor baseline function may further de-stabilize systolic performance. Hence an aggressive approach should be adapted toward prevention and early treatment of factors known to precipitate the incidence of alternans. Hypovolemia, administration of vasodilators, rapid atrial pacing, dobutamine administration, ventricular premature contractions, hypocalcemia, hypercapnea under halothane anesthesia and administration of large boluses of fentanyl have been implicated in generation of PALT. None of them were involved in our scenario. We attribute this alternation in our patient to distortion of ventricles, which impaired the ventricular filling. It was not observed after the sternal closure and in postoperative period.
The potential role of TEE in dealing with the PALT has been summarized in [Table 2]. TEE helps in identifying prosthetic valve dysfunction. The transvalvular gradient and cardiac output estimated from the beat of a small VTI is expected to be much less than the beat of a high VTI. Keeping this in mind, an echocardiographer should avoid performing these calculations in the presence of PALT.
In summary, the PALT can occur as a result of cardiac handling during surgical hemostasis after AVR in the presence of severe left ventricular dysfunction. At a constant Doppler cardiac cycle interval, the systolic ejection phase of a larger beat lasts longer than the smaller beat. Characteristically, the period between the AV end-systolic excursion preceding and following a large beat remains longer than that between a smaller beat. The TEE has a potential role in dealing with this phenomenon in the intraoperative period.
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