Transient systolic anterior motion with junctional rhythm after mitral valve repair in the intensive care unit

We identified two important clinical issues. Junctional rhythm can cause deterioration of SAM, LVOTO, and MR, and atrial pacing can improve hemodynamics in unstable normal sinus rhythm. TEE is useful for the identification of causes of unstable hemodynamics after cardiac surgery in the ICU as well as in the operating room.

First, junctional rhythm can cause deterioration of SAM, LVOTO, and MR and atrial pacing can improve hemodynamics. Some mechanisms of SAM are related to geometric factors, kinetic factors, and structural abnormalities [3]. Geometric factors include annular undersizing, anterior mitral valve displacement, low anterior:posterior leaflet length ratio, reduced mitro-aortic angle, and distance reduction between the MV coaptation point and interventricular septum [4]. Hyperdynamic LV is a kinetic factor. Structural abnormalities include small LV, chordal anomalies, bulging interventricular septum, papillary muscle displacement, redundant posterior leaflet, and redundant anterior leaflet. Some authors reported that ventricular pacing or atrioventricular sequential pacing can affect the severity of SAM [5, 6]. In the present case, junctional rhythm caused deterioration of SAM. Junctional rhythm causes atrioventricular dyssynchrony and loss of atrial kick. These can contribute to decreases in mean arterial pressure and cardiac output by approximately 15% and the decreases can be accentuated in patients with heart disease [7, 8]. The mechanism by which junctional rhythm causes deterioration of SAM might be the impairment of LV filling due to atrioventricular dyssynchrony and loss of the atrial kick in junctional rhythm. In addition, underlying right ventricular dysfunction also plays a role in LV underfilling. There are some causes of RV dysfunction after cardiac surgery including inadequate myocardial protection during cardiac arrest, myocardial ischemia due to residual air, high pulmonary vascular resistance, and inadequate settings of mechanical ventilation [9]. In the present case, the right cause of RV dysfunction is unclear; however, long CPB, residual air, compression for control of bleeding by the surgeons might be related to RV dysfunction.

The management of SAM depends on the underlying mechanism and severity. In most cases, volume loading, discontinuation or reduction of inotropic drugs, and administration of beta blockers and vasopressors can resolve SAM [10‐12]. It has been demonstrated that conservative hemodynamic maneuvers for intraoperative transient SAM are reliable and result in good clinical outcomes, although some cases require surgical correction with second cardiopulmonary bypass [13]. Since the present case had right ventricular failure, maintaining normal sinus rhythm seemed to be more important than in patients without right ventricular failure [14].

Second, TEE in the ICU is useful for the identification of causes of unstable hemodynamics after cardiac surgery. The usefulness of echocardiography for diagnosis and decision-making has been shown in the ICU, and basic echocardiography skills have become mandatory for all intensivists in some guidelines [15‐17]. On the other hand, the use of TEE is reserved for instances in which diagnostic information for clinical decision-making cannot be obtained by TTE in a timely manner. However, TEE is considered an advanced skill and is not considered a minimum requirement for intensivists [17‐19].

After cardiac surgery, obtaining useful images is sometimes difficult due to the narrowing of acoustic windows caused by the surgical incision, drapes, and drains. In addition, unclear images are insufficient for clinical decision-making in critical situations. Strengths of TEE include less dependence on operator skills and better spatial resolution compared to that of TTE [20]. In the present patient, the causes of recurrent hemodynamic exacerbation were different and could not be diagnosed without TEE. Basic hemodynamic assessment with TEE is not that difficult and training in basic TEE skills with simulators is evolving [21, 22]. Thus, the barrier to learning of basic TEE skills by intensivists can be overcome.

This case report shows that junctional rhythm can cause deterioration of SAM, LVOTO, and MR, and can lead to unstable hemodynamics in a patient with right ventricular failure after MVR. Atrial pacing can resolve SAM, LVOTO, and MR and can improve hemodynamics in a patient with unstable normal sinus rhythm. TEE in the ICU can play a pivotal role in clinical decision-making. Given that there are various causes of hemodynamic deterioration after cardiac surgery and some cannot be diagnosed without TEE, both TTE and basic TEE skills are required for intensivists.