Anesth Analg 2002;94:310-312
© 2002 International Anesthesia Research Society
CARDIOVASCULAR ANESTHESIA
An Intraoperative Diagnosis of Dynamic Left Ventricular Outflow Tract Obstruction Using Transesophageal Echocardiography Leads to the Treatment with Intravenous Disopyramide
Minako Ashidagawa, MD,
Maria Ohara, MD, and
Yasuhiro Koide, MD
Department of Anesthesiology, Yokohama City University School of Medicine, Yokohama, Japan
Address correspondence and reprint requests to Yasuhiro Koide, MD, Department of Anesthesiology, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004 Japan. Address e-mail to hiro{at}med.yokohama-cu.ac.jp
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Abstract
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Hypertrophic obstructive cardiomyopathy (HOCM) is an uncommon familial disorder, traditionally characterized by asymmetric septal hypertrophy and left ventricular outflow tract (LVOT) obstruction (1). It is now recognized that HOCM may also include those patients with secondary left ventricular hypertrophy (LVH) and dynamic LVOT obstruction. In particular, a syndrome with similar clinical and echocardiographic findings has been identified in elderly patients exhibiting concentric LVH with chronic hypertension, aortic stenosis, or sigmoid-shaped septum (2).
IMPLICATIONS: During surgery, dynamic left ventricular outflow obstruction (LVOT) can potentially occur frequently, but diagnosis may be less frequent. When circulatory disturbance occurs with suspicion of LVOT obstruction, transesophageal echocardiography can provide exact proof of diagnosis and basis for immediate treatment.
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Case Report
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A 61-yr-old woman with hypertension controlled with diltiazem 60 mg/day was scheduled for right total knee arthroplasty. Her medical history included systemic lupus erythematosus, lupus nephritis, and bronchial asthma. Because she had occasionally complained of palpitation and dyspnea at rest, extensive preoperative evaluations were performed. On examination with transthoracic echocardiography, mild aortic valve stenosis (AS) with a maximum pressure gradient (PG) of 30.2 mm Hg, moderate mitral valve regurgitation (MR), and mild LVH with no areas of asynergy were observed. Monitoring by a Holter electrocardiogram (ECG) revealed ST depression (1.5–2.0 mm). A mild limited ischemic area in the left ventricular (LV) posterior wall was suspected by scintigraphic evaluation.
After routine monitors were placed, general anesthesia was induced with propofol 80 mg, fentanyl 100 µg, and vecuronium 5 mg. Anesthesia was maintained with nitrous oxide and isoflurane in oxygen and combined with 0.25% bupivacaine epidural anesthesia. Arterial blood pressure (ABP), central venous pressure (CVP) and a multiplane transesophageal echocardiography (TEE) were used in addition to the routine monitors.
Before surgery was started, TEE examination was performed. The sigmoid-shaped septum without appearance of LVOT obstruction was found along with mild MR, but no significant AS (aortic valve area 2.0 cm2 by planimetry). Her hemodynamic variables were stable until the tourniquet was released, showing systolic ABP of 120–140 mm Hg and CVP of 7–9 mm Hg. The ABP waveform was unremarkable in morphology.
After tourniquet release, massive bleeding of more than 3000 mL occurred within an hour. Rapid transfusion was required to maintain systolic ABP more than 80 mm Hg and CVP more than 4 mm Hg. Her heart rate gradually increased to 100–110 bpm; simultaneous ST depression (II–0.8 mm, V5–1.4 mm) occurred in the ECG monitor (Fig. 1A). Her hemodynamic condition was expected to recover after showing an increase in CVP to 8 mm Hg. However, the ABP did not increase and its wave form morphology changed to a peculiar bifid shape termed a "spike-and-dome" configuration (Fig. 1B). TEE revealed LVOT obstruction with systolic anterior motion (SAM) of the mitral valve, moderate MR (Fig. 1C) and LV hypercontraction without asynergy. At this point, the diagnosis of dynamic LVOT obstruction and myocardial ischemic change was confirmed, and IV bolus injection of disopyramide 35 mg (1 mg/kg) was chosen for immediate treatment. After 1 min, the severity of LVOT obstruction and MR were reduced in the TEE monitors (Fig. 1E). The ABP waveform improved to normal shape (Fig. 1D). ABP increased from 125/62 to 157/82 mm Hg and CVP decreased from 8 to 3 mm Hg. The ST depression in the ECG monitor improved rapidly (Fig. 1A).
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Figure 1. A, trendgrams of arterial blood pressure (ABP), heart rate (HR), central venous pressure (CVP), and ST deviation after tourniquet release. B, the waveform of ABP showing "spike-and-dome" configuration before IV bolus injection of disopyramide. C, color Doppler transesophageal echocardiogram showing marked turbulent flow in left ventricular outflow tract and mitral valve regurgitation before treatment with disopyramide. D, the normal waveform morphology of ABP after the treatment. E, color Doppler transesophageal echocardiogram after the treatment. LA = left atrium; LV = left ventricle; Ao = ascending aorta
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Postoperatively the patient was treated with diltiazem 200 mg/day to control ischemic changes in the Holter ECG and was discharged 69 days after surgery. Disopyramide was not chosen because of renal dysfunction.
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Discussion
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During surgery, a hyperdynamic contractile state of the LV because of operative stimuli and significant hypovolemia resulting from massive bleeding are occasionally observed (3). In that situation, the dynamic LVOT obstruction could occur intraoperatively even if the patient were preoperatively asymptomatic or undiagnosed (4). However, the diagnosis during surgery is relatively difficult because of the dynamic properties and loss of clinical signs. The contribution of echocardiography to the diagnosis has increased the number of asymptomatic patients diagnosed (5). The echocardiographic features of LVOT obstruction are characterized by SAM of the coapted mitral valve, marked turbulence of systolic flow through the LVOT, and MR (2). TEE has the superior diagnostic potential because of the high-quality image compared to transthoracic echocardiography.
The intraoperative treatment of dynamic LVOT obstruction is initially focused on normalization of loading conditions. Rapid infusion and transfusion is recommended for any low preload condition. A vasopressor such as phenylephrine is recommended when afterload is reduced. However, in this case, rapid transfusion therapy alone was not enough to relieve the dynamic LVOT obstruction, although CVP reached 8 mm Hg. The LV pressure overload which led to ST depression required immediate additional therapy, thus reducing the severity of LVOT obstruction secondary to LV hypercontractility.
Beta-blockers and calcium channel blockers, which decrease LV contractility, are effective in reducing the PG in many patients with HOCM, but these drugs are sometimes insufficient (6–8). Disopyramide, a type 1a antiarrhythmic drug, was reported to be more effective than propranolol in reducing the PG (9–11). This may mainly be because disopyramide has less negative inotropic effect compared with propranolol, while it potentially increases systemic vascular resistance, and improves diastolic function (10).
Based on reports from nonsurgical situations, we introduced alternative therapy with disopyramide intraoperatively, although conventional therapy with a short-acting selective ß1-blocker is also effective. Disopyramide should be used very carefully intraoperatively because of its powerful negative inotropic effect and its long elimination half-time (5 to 7 hours). Precise diagnosis is necessary when disopyramide is administrated because dynamic LVOT obstruction presents with symptoms and findings mimicking AS or coronary artery disease.
In conclusion, TEE was a useful intraoperative tool for diagnosis of dynamic LVOT and monitor for the treatment. With full assurance of the precise diagnosis, therapy was initiated immediately without worsening of circulatory collapse, pulmonary congestion, or myocardial ischemia.
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References
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Accepted for publication October 2, 2001.
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