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Diastolic shunt after ventricular septal perforation following acute myocardial infarction

Garcilazo Enrique M.D*., McLoughlin Mario, Loredo Stella M.D

* Director, Ultrasound Imaging and Hemodinamic Laboratory
San Patricio Hospital
Buenos Aires, Argentina

Introduction
Methods
Discussion
Conclusions
References

Introduction: Rupture of the interventricular septum is a serious complication of acute myocardial infarction (AMI) and severe hemodinamic deteriorization develops in 80% of patients. The defect is usually find in anteroapical septum 1 and 65 to 75% of AMI affect anterior wall. Holosytolic murmur shows the left to right communication and it extend to diastolic phase. We present here 2 cases studied with color doppler showing systolic-diastolic left to right shunt after AMI.

Methods: Two patients with myocardial infarction who had shown sudden onset of a pansystolic murmur in the acute stage of their disease, strongly suggesting ventricular septal rupture. Commercially available two-dimensional Doppler systems were used, with color flow imaging, General Electric, LOGIQTM500, with cardiologic software. The transducers were sectorial phased array 3,5 MHz and convex 3,5 MHz, both with wide band. ( S316 and C364, 2,2 - 4 MHz.)

Case I: The patient was a 75 year-old-man, with anterior AMI and right atrial, systolic/diastolic pulmonary and wedge pressures of 7.6, 60/32 and 32 mm of Hg. respectively. Three days after chest pain presents holosystolic murmur and echocardiographic examination detected a septal defect. Color doppler examination showed a systolic/diastolic from left ventricle to right ventricle. Cardiac catheterization revealed total occlusion of the anterior descending artery and severe stenosis of cincunflex artery. Cardiac surgery was performed and the large septal defect was closed.

Case II: A 78 -year-old woman presented with chest pain and anterior AMI. An apical holosystolic murmur was heard and color doppler examination showed systolic/diastolic left to right shunt. The patient developed cardiogenic shock and died before cardiac catheterization.

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Discussion: Systolic flow from LV to RV in septal perforation after AMI has been demonstrated by angiography and doppler examination. Miyatake 2, using grey scale doppler showed diastolic flow between both ventricles in 5 of 6 patients with interventrcular communication post AMI and later, Bansal 3 reported 15 patients with septal perforation after AMI and 14 showed systolic/diastolic flow (6 patient were examined using color doppler equipment). However, authors have concentrated the attention in systolic flow and importance and signification of diastolic flow has not been considered. Although diastolic murmur can be occasionally heart 2 proving interventricular diastolic flow, or a prominent V waves in wedge pressure can be seen 4, we think that there are some reasons why relevance of diastolic flow has been overlooked.

1- Is hard to certificate that diastolic murmur is produced by interventricular flow and not by other abnormalities in patients with complex hemodynamic condition.
2- There is no systolic/diastolic difference in oximetry.
3- Usually, ventriculography in left anterior oblique position shows IV systolic communication but, as volume overload in RV produces contrast dilution, is difficult to show diastolic flow from LV to RV.
4- Although pulsed doppler examination is able to demonstrate diastolic flow, septal perforation can be missed in 2D echocardiographic examination (because is axially oriented in septum and out of focus of transducer) and as a consequence, sample volume is not positioned at the perforation to make measurements. Besides, in four chamber view, jet direction is perpendicular to beam and doppler signal is very difficult to find.
5- Transesophageal color doppler examination is very difficult to perform in disneic or respiratory assisted patients, which also applies to the rest of medical examinations.

Relative to hemodynamics, measurements shows a mean LV end diastolic pressure of approximately 22 mm of Hg. while pressure in RA is approximately 10 mm of Hg. The pressure difference between LV and RV is approximately 12 mm of Hg. This difference, associated to a 15 mm. hole produces important diastolic flow.

At the systolic beginning, LV pressure forces blood and pressure to RV. As RV has volume overload (because interventricular shunt and tricuspid flow) and, which is most important, is contracting, RV compliance is low and pressure rises and produces the opening of pulmonary valve and ejection of blood from both ventricles in pulmonary artery. So, interventricular jet velocity measurement allows PA systolic pressure measurement3,4.

As PA/Aortic flow ratio is approximately 2,5:1, RV collaboration explain how this relationship can be maintained because infected LV is probably unable to produce output for PA and Aorta simultaneously.

Conclusions: Although systolic shunt in left to right shunt post AMI is well known the diastolic component is underestimated and the flow in this phase of cardiac cycle might be very important in the hemodynamic changes that follows the septal perforation.

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Acknowledgements: We would like to thank doctors SARMIENTO Ricardo and BLUGUERMAN Julio, from INSTITUTO CARDIOVASCULAR INTEGRAL DEL HOSPITAL ISRAELITA, Hemodinamic laboratory.

References:

1. Norell MS, Gershlick AH, Pillai R et. al: "Ventricular septal rupture complicating myocardial infarction: is earlier surgery justified?", European Heart Journal, 1987; pgs. 1281-1286.
2. Miyatake K, Okamoto M, Kinoshita N, Park YD, Nagata S, Izumi S, et al: "Doppler Echocardiographic Features of Ventricular Septal Rupture in Myocardial Infarction". J Am Coll Cardiol, 1985; 5: pgs. 182-187.
3. Bansal RC, Eng AK, Shakudo M: "Role of two-dimensional echocardiography, pulsed, continuous wave color flow Doppler techniques in the assessment of ventricular septal rupture after myocardial infarction". Am J. Cardiol, 1990, 65: pgs. 852-860.
4. Boucher CA: "Case Records of the Massachussets General Hospital.", N. Engl J. Med, 1996, 334: pgs. 105-111.
5. Faletra F. Moreo A. Frigerio M. Ciliberto GR, Mauri F, Mafrici A. Cantoni S, Donatelli F, Quaini E, De Vita C: "Usefulness of color Doppler in the diagnosis of ventricular septal rupture after myocardial infarction"-. G Ital Cardiol, 1990, 20: pgs. 1101-1106.

 

Questions, contributions and commentaries to the Authors: send an e-mail message (up to 15 lines, without attachments) to echo-pcvc@pcvc.sminter.com.ar , written either in English, Spanish, or Portuguese.

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Update
Oct/31/99


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