Acute coronary artery dissection after aortic valve replacement

Machado, Fernando de Paula; Sampaio, Roney Orismar; Mazzucato, Fernanda Lopez; Tarasoutchi, Flávio; Spina, Guilherme Sobreira; Grinberg, Max

doi:10.1590/S0066-782X2010000200026

Abstracts

Late aortic dissection can occur after aortic valve replacement surgery, but rarely in the first postoperative month. Coronary artery dissection is rare and usually occurs after coronary angiography. We report a rare case of coronary artery dissection followed by myocardial infarction in the immediate postoperative period of a successful aortic valve replacement with a good postoperative evolution.

Aortic valve; acute coronary syndrome; coronary vessels; dissection

A dissecção de aorta pode ocorrer tardiamente após cirurgia de troca de valva aórtica e raramente no primeiro mês pós-operatório. A dissecção de artéria coronariana é rara e normalmente ocorre depois de angiografia coronariana. Relata-se um caso raro de dissecção de artéria coronária, seguido de infarto do miocárdio, no pós-operatório imediato de troca de valva aórtica com correção e evolução bem-sucedidas.

Valva aórtica; síndrome coronariana aguda; vasos coronários; dissecção

La disección de aorta puede ocurrir tardíamente tras cirugía de reemplazo de válvula aórtica y raramente en el primer mes postoperatorio. La disección de arteria coronaria es rara y normalmente ocurre después de angiografía coronaria. Se relata un caso raro de disección de arteria coronaria, seguido de infarto de miocardio, en el postoperatorio inmediato de reemplazo de válvula aórtica con corrección y evolución exitosas.

Válvula aórtica; síndrome coronario agudo; vasos coronarios; disección

CASE REPORT

Instituto do Coração do Hospital das Clínicas da Universidade de São Paulo, São Paulo, SP - Brazil

Mailing address

ABSTRACT

Late aortic dissection can occur after aortic valve replacement surgery, but rarely in the first postoperative month. Coronary artery dissection is rare and usually occurs after coronary angiography. We report a rare case of coronary artery dissection followed by myocardial infarction in the immediate postoperative period of a successful aortic valve replacement with a good postoperative evolution.

Key Words: Aortic valve / surgery; acute coronary syndrome; coronary vessels; dissection.

Introduction

The prevalence of aortic dissection after aortic valve replacement surgery is estimated at 0.6%. Usually, it occurs one month to 16 years after the cardiac surgery. In addition, 13% of patients with aortic dissection had previously undergone aortic valve replacement¹. Aortic dissection after cardiac surgery with cardiopulmonary bypass and myocardial protection using cardioplegic solution is even rarer (0.16% of cases)². Cannulation of the thoracic aorta associated with clamping and anastomosis is a known cause of this phenomenon. Most cases are recognized during surgery and promptly corrected.

Coronary artery dissection can occur by itself or accompanied by aortic dissection, usually after catheter manipulation at the time of coronary angiography, or even spontaneously. The main complication is arterial occlusion, which used to occur in 11% of angioplasties in the pre-stent era. The incidence of this event has been reduced to less than 1% with the introduction of stents³.

Below we give the description of a case of acute myocardial infarction caused by coronary artery dissection after aortic valve replacement.

Case Report

A 73-year old woman, with a history of high blood pressure, hypothyroidism, asthma, and severe aortic stenosis associated with moderate aortic regurgitation had functional class III (New York Heart Association) at the time of surgery. The electrocardiogram showed preoperative left ventricular hypertrophy (Fig. 1A). The echocardiogram showed a mean gradient of 61 mmHg, and a peak gradient of 105 mmHg, with a left ventricular ejection fraction of 0.65 (Teicholz method). The coronary angiography showed an 80% obstruction of the diagonal artery (small caliber and short length), coupled with significant left ventricular hypertrophy, and an 80 mmHg pressure gradient between the left ventricle and the aorta.

During surgery, we found a calcified tricuspid aortic valve, which was replaced by a bioprosthesis number 23; the cardiopulmonary bypass time was 84 minutes. The surgery had no complications, except for the infusion of sodium nitroprusside for blood pressure control.

On the second day after surgery, an ST-segment elevation in the anteroseptal wall (Figure 1B) and increased creatinine kinase MB levels were observed. The patient had no symptoms until the third day after surgery, when she presented typical anginal pain at rest. Once the diagnosis of acute myocardial infarction was hypothesized, she was referred for emergency coronary angiography (Figure 2). The angiography showed a dissection extending from the left main coronary artery to its branches, i.e., the left anterior descending artery and the left circumflex artery. The dissection also affected the right coronary artery. The patient underwent coronary artery bypass grafting surgery: the left internal mammary artery was anastomosed to the left anterior descending artery, and saphenous vein grafts were placed from the aorta to the left marginal branch of the circumflex artery and to the right coronary artery. There was no dissection of the aorta.

After revascularization, the patient remained in good condition, with resolution of angina and ECG abnormalities.

Comments

We describe a case of coronary artery dissection after aortic valve replacement surgery, probably due to high blood pressure in the perioperative and postoperative periods. Acute myocardial infarction was diagnosed by electrocardiogram changes and myocardial necrosis markers, and angina appeared later on. There was no relief of angina after blood pressure control, leading to an urgent hemodynamic study with subsequent surgical treatment.

Although not very common, there are case reports of aortic dissection after aortic valve replacement. However, the authors have found no descriptions of cases in which a coronary artery dissection occurred after aortic valve replacement^1,2. Aortic wall weakness or thinness, usually due to collagen deficiency, and aortic regurgitation are independent risk factors for the occurrence of proximal aortic dissection at the time of aortic valve replacement. Other risk factors include high blood pressure and a bicuspid valve⁴.

Aortic dissection during surgery is a rare but serious complication after cardiac surgery, and its incidence varies from 0.16% to 0.25%⁵. Predisposing factors include atherosclerosis, significantly high blood pressure, cystic medial necrosis, collagen vascular diseases, and a thin or dilated ascending aorta^5,6. The dissection is often identified after aortic declamping, but may also occur at the time of cannulation, clamping, or decannulation. In this situation, a transesophageal echocardiogram is a good and practical method to confirm the diagnosis. If the expansion of the dissection is limited, a small plication technique can be used without mobilization of the aortic cannula.

When major dissections or low output syndrome occur, the cannula should be removed to another arterial access, such as the femoral and axillary arteries⁷. In our case, there were no complications during surgery that could be indicated as the cause of the coronary dissection.

Acute myocardial infarction can occur after cardiac surgery, especially after coronary revascularization. Modern methods of myocardial protection and surgical techniques have been developed. However, occasionally there are cases of atherosclerotic disease in the distal coronary artery, spasm, embolism or thrombus in native vessels or grafts⁷. Other causes of myocardial ischemia are inadequate myocardial protection during surgery, increased oxygen demand, as seen in patients with left ventricular hypertrophy, and hemodynamic instability. The diagnosis of acute infarction in the postoperative period of a cardiac surgery can be difficult due to the absence of pain during sedation and analgesia, and the frequent elevation of myocardial necrosis markers by surgical manipulation. In this patient, there were a single prior obstruction of the coronary artery in a branch of little importance and left ventricular hypertrophy, but increased enzyme levels associated with angina indicated the need for coronary angiography.

Coronary artery dissection can cause myocardial infarction, particularly after percutaneous transluminal coronary angioplasty. Another rare form is a spontaneous dissection of the coronary arteries. The vast majority (80%) occurs in young women in the postpartum period or in those who use oral contraceptives. The treatment varies, but follows the usual procedure for other causes of acute myocardial infarction⁸.

Our patient was a rare case of coronary artery dissection after aortic valve replacement, probably due to high blood pressure in the perioperative and postoperative periods. Acute myocardial infarction was diagnosed by ECG changes and laboratory markers of myocardial necrosis with late onset of angina. Its refractoriness indicated coronary angiography with subsequent emergency surgical treatment.

Potential Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Sources of Funding

There were no external funding sources for this study.

Study Association

This study is not associated with any post-graduation program.

References

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