Catheterization and Cardiovascular Diagnosis 38:377-378 (1996)

Periodic Intermittent Electromechanical Dissociation: Hemodynamic Correlate of a Malfunctioning Mechanical

Prosthetic Valve

Dipen Shah, DNB, M. Vijaykumar, DM, K. Chandrasekhar, DM, K.N. Reddy, DM, and M.R. Girinath, Mch

We describe a patient who developed the unusual haemodynamic phenomenon of peri- odic intermittent electromechanical dissociation during regular sinus tachycardia about 20 hours after mitral valve replacement with a tilting disc mechanical prosthesis. Echo- cardiographic confirmation allowed prompt and life saving corrective surgery for a stuck prosthetic valve disc.

Key words: electromechanical dissociation, periodic, stuck mitral prosthetic valve, he- modynamic trace

- 1996 wiiey-~ina. Inc.

INTRODUCTION

Electromechanical dissociation (EMD) is a well- known mechanism of cardiac arrest and is associated with a grim prognosis [ 11. Prolonged cardiac arrest with global ischemia or diffuse disease, cardiac tamponade from hemopericardium, pulmonary embolism, and mal- functioning prosthetic valves can all result in EMD. We report on a patient who developed the unusual hemody- namic phenomenon of periodic intermittent EMD attrib- utable to a stuck mechanical prosthetic valve.

CASEREPORT

A 36-year-old man with chronic calcific rheumatic mi- tral valve disease (severe mitral stenosis with moderate mitral regurgitation) in sinus rhythm underwent mitral valve replacement, in view of progressive symptoms. A size 27-m Medtronic Hall tilting disc mechanical pros- thetic valve was secured in the mitral position, using standard techniques. The valve was oriented to allow the disc to open posteriorly and through the right. Moderate hypothermia, roller pump cardiopulmonary bypass, and crystalloid cardioplegia were used. The heart picked up in sinus rhythm after direct current defibrillation, and cardiopulmonary bypass was gradually withdrawn. Al- though he remained initially stable, sudden hypotension occurred about 20 hr after surgery. A characteristic trace was noted on the monitor display (Fig. 1). Sinus rhythm was maintained (regular tachycardia at 11Ymin) with a periodic decrescendo arterial pressure trace. Maximal and near-normal arterial pressure was noted transiently with every seventh or eighth beat. An urgent bedside

0 1996 Wlley-Liss, Inc.

echocardigram revealed that the prosthetic valve disc opened fully only intermittently, coinciding each time with the maximal arterial pressure on the monitor during continuing sinus tachycardia.

The patient was immediately rushed to the operating theatre, and cardiopulmonary bypass was urgently rein- stituted. Under moderate hypothermia, the LA was re- opened. The mitral prosthetic disc was found to be stuck in the closed position with a small bit of chordae wedged between the disc and the valve housing. The valve was carefully prised open, the remaining tissue below the valve was excised, and the prosthesis was sutured back in place after reorienting its opening. After defibrillation sinus rhythm was restored, and cardiopulmonary bypass was gradually withdrawn. The subsequent postoperative course was complicated by a hemothorax and continuing sanguineous chest tube drainage with significant blood loss. He was also treated empirically for suspected early postoperative infective endocarditis with 4 weeks of parenteral antibiotic therapy, but he made a complete recovery.

DISCUSSION

Electromechanical dissociation (EMD) has been de- fined as elcctrical depolarization of the heart (chiefly the

From the Departments of Cardiology and Cardiothoracic Surgery, Apollo Hospitals, Madras, India.

Received May 4, 1995; revision accepted December 20, 1995.

Address reprint requests to Dr. Dipen Shah, Department of Cardiol- ogy, Apollo Hospitals, 21, Greames Lane; Off Greames Road, Ma- dras 600 006, India.

378 Shah et al.

a

-1

~ ~~

Fig. 1. A diagrammatic representation of the radial artery pres- sure tracing and surface ECG showing the phenomenon of pe- riodic intermittent electromechanical dissociation: A maximal and near normal arterial pressure pulse noted every eighth beat with practically no pressure pulse in between, but with continu- ing and stable sinus tachycardia throughout (drawing not to scale).

ventricles) without a cardiac output [3]. EMD is a com- mon preterminal event (thought to be due to loss of the excitation-contraction coupling mechanism) in patients with global ischemia or diffuse disease [2]. However, the so-called secondary form of EMD is characterized by obstruction of return to the heart and is known to occur with malfunctioning prosthetic valves [4].

Although pulsus alternans due to a stuck prosthetic valve has been reported [ 5 ] , to the best of our knowl- edge, this hemodynamic pattern of an intermittent peri- odic decrescendo EMD in continuing sinus rhythm has not been described. We believe that increasing LA pres- sures were able to open fully the obstructed mitral pros- thetic disc intermittently only, resulting in near normal stroke volume for that cycle with a near normal pulse

tracing. This decompression of the LA would then pre- sumably require recruitment of LA pressure during sev- eral subsequent pulseless or near pulseless cycles (with an obstructed disc) for full reopening of the valve, thereby leading to this pattern of periodic intermittent EMD. Although lack of opening of stuck or thrombosed prosthetic valves has been demonstrated by M mode and Doppler echocardiographic techniques we are not aware of any report of such a hemodynamic manifestation. The nature of the emergency precluded recording of the ac- tual trace; however, Figure 1 is a diagrammatic repre- sentation.

Recognition of this hemodynamic pattern should lead to immediate consideration of an intermittent intracar- diac obstruction such as a malfunctioning prosthetic valve. Appropriate investigations such as echocardio- graphy can provide confirmatory evidence and allow for life-saving surgical correction of the problem.

REFERENCES

1. Vincent JL. Thijs L, Michaels S, Silverberg RA: Clinical and experimental studies on electromechanical dissociation. Circula- tion 64:18-27, 1981.

2. Myerburg RJ, Castellanos A: Cardiac arrest and sudden cardiac death in Braunwald E (4): “Heart Disease-A Textbook of Car- diovascular Medicine.” 4th Ed. Philadelphia: WB Saunders, 1992. p 769.

3. Ewy GA: Defining electromechanical dissociation. Ann Emerg Med 13:830-832, 1984.

4. Matsuda H, Sato H, Hosokawa Y, Yamamoto S, Nakamura K: Closed stuck valve diagnosed by echocardiogram immediately after mitral valve replacement; a case report. [In Japanese.] Ky- obu Geka 44:864-866, 1991.

5. Jortner RT, Rafaelof B, Tunick PA, Kronzon I: Pulsus alternans as a sign of prosthetic valve dysfunction. Am Heart J 127:221- 224, 1994.

6. Tomizawa Y, Kitamura N, Minoiji T, Irie T, Yamaguchi A, Ootaki M, Tamura H, Atobe M: Stuck prosthetic valve caused by pyrolytic carbon disk wear. Chest 91:798, 1987.