Acquired dynamic left ventricular outflow tract obstruction complicating acute anterior myocardial infarction: serial echocardiographic and clinical evaluation

Frequent POCUS and auscultation for an earlier diagnosis of takotsubo syndrome and unraveling of its pathophysiology: The possible crucial role of LVOTO

There is ample literature associating LVOTO with hypertension, AMI, LV hypertrophy, sigmoid septum, HCM, and TTS, particularly in midde aged/elderly/postmenopausal women, suggestive of a causal role for LVOTO in the pathophysiology of TTS. Although there is significant evidence that TTS is triggered by a sudden autonomic sympathetic nervous system surge and/or elevated blood-ridden catecholamines, the exact pathophysiologic trajectory leading to the clinical expression of the disease is still being debated. This review expounds on the possibility that LVOTO is a causal early component of this trajectory, and proposes that TTS is a malady within the broad spectrum of the myocardial ischemic injury/stunned myocardium states. The postulated underlying mechanism by which LVOTO causes TTS is a sudden abterload rise, with resultant oxygen/energy supply/demand mismatch, leading to a transient myocardial ischemia/injury myocardial stunning state. This needs to be explored painstakingly, and this review includes some suggestions for such undertaking. Ellucidation of the pathophysiology of TTS, and possible proof about a mechanistic role of LVOTO, may ensure that our current pharmacological and device panoply is adequate for the management of TTS.

Dynamic left ventricular outflow tract obstruction in a patient with acute coronary syndrome and without the apical akinesia: Potential alternative mechanisms causing a dynamic left ventricular outflow tract obstruction other than a compensatory basal hyperkinesis

The mechanism for dynamic left ventricular outflow tract obstruction (LVOTO) after acute coronary syndromes (ACS) is thought to be apical infarction with compensatory hyperkinesia of the residual normally perfused basal segments of the myocardium. However, herein, we report a patient with ACS and dynamic LVOTO (peak gradient of 250 mm Hg at rest) that could not be secondary to apical akinesia. We propose a potential alternative mechanism leading to dynamic LVOTO in ACS, namely, the interplay between sigmoid septum, basal hyperkinesis, and outflow tract narrowing induced by afterload reduction due to acute myocardial ischemia itself.

Manifestation of latent left ventricular outflow tract obstruction caused by acute myocardial infarction: An important complication of acute myocardial infarction

BACKGROUND

Although transient left ventricular outflow tract (LVOT) obstruction is reported as a complication with acute myocardial infarction (AMI), the mechanisms and features of LVOT obstruction in AMI are unclear.

METHODS AND RESULTS

Herein, we present two cases of transient LVOT obstruction with anteroseptal AMI. The features of these two cases were one-vessel disease (1-VD) of the left anterior descending artery (LAD) and maintenance of blood flow to the major septal branch (SB). Moreover, LVOT obstruction was revealed after dobutamine infusion in the chronic phase and the aorto-septal angle was low in these two cases, meaning that latent LVOT obstruction was due to sigmoid-shaped septum.

CONCLUSIONS

Latent LVOT obstruction would be manifested in the acute phase of AMI. 1-VD of LAD and the maintenance of major SB blood flow are important factors with respect to the manifestation of latent LVOT obstruction.

Isolated dynamic left ventricular outflow tract obstruction can cause hypotension that rapidly responds to intravenous beta blockade

Dynamic left ventricular outflow tract obstruction occurs in hypertrophic cardiomyopathy, stress cardiomyopathy, acute coronary syndromes, and with inotrope use. We describe three critical care patients who developed "isolated" left ventricular outflow tract obstruction with hypotension in the absence of these precipitants. Systolic anterior motion of anterior mitral valve leaflet with peak left ventricular outflow tract gradients of greater than 120 mmHg was noted in Cases 1 and 2. Under close supervision, intravenous (IV) β blocker was initiated with 5 mg metoprolol repeated every 5 minutes up to 15 mg and continued to maintain heart rate less than 70 beats/min. IV fluids were replaced aggressively. Bedside Doppler echocardiogram confirmed near normalization of left ventricular outflow tract gradient with improvement in systolic anterior motion and hypotension within minutes after IV β blocker confirming its specific therapeutic effect. Isolated left ventricular outflow tract obstruction can occur in the absence of recognized precipitants. Early recognition is crucial because this potentially fatal condition responds well to adequate β blocker and IV fluids with rapid relief of hypotension and symptoms.

Perioperative transient left ventricular apical ballooning syndrome: Takotsubo cardiomyopathy: a review

Transient left ventricular apical ballooning syndrome (TLVAB), also known as Takotsubo cardiomyopathy, is a cardiac syndrome characterized by transient left ventricular dysfunction in the absence of obstructive atherosclerotic coronary artery disease. An episode of emotional and/or physiologic stress frequently precedes presentation of this syndrome. TLVAB may initially present as an acute coronary syndrome characterized by chest pain, pulmonary edema, electrocardiographic changes, elevated cardiac enzymes, and cardiogenic shock. This syndrome is still underestimated today and the potential appearance of TLVAB during the perioperative period can be a great challenge. Adequate beta-blockade is the mainstay in the treatment of patients with TLVAB during the acute phase and also for long-term management.

Mechanical versus pharmacologic support for cardiogenic shock

Dynamic left ventricular outflow tract obstruction is a rare cause of cardiogenic shock after an acute myocardial infarction. A case is presented where inotropic support and an intra-aortic balloon pump aggravated the cardiac hemodynamics by this mechanism. The circulatory support provided by Impella 2.5 heart pump, in addition to discontinuation of inotropic support and intra-aortic balloon pump, allowed stabilization and successful percutaneous revascularization.

Echocardiography in stress cardiomyopathy and acute LVOT obstruction

Widespread use of echocardiography has contributed to more frequent recognition of takotsubo stress cardiomyopathy. Initial presentation is similar to acute coronary syndrome and the acute course can be complicated by heart failure, arrhythmias, dynamic left ventricular outflow tract obstruction, hypotension and death. We briefly review the clinical presentation and propose a unified diagnostic algorithm for cardiologists acutely managing this cardiac emergency. We highlight the central role of echocardiography and emphasize the nuances of this peculiar acute cardiomyopathy from an echocardiographers' perspective.

Unexplained hypotension: the spectrum of dynamic left ventricular outflow tract obstruction in critical care settings

OBJECTIVE

To illustrate the clinical and hemodynamic abnormalities caused by dynamic left ventricular outflow tract obstruction (LVOTO) in critical care setting.

DESIGN

We reviewed cases referred to Cardiology with echocardiographic evidence of LVOTO and their clinical presentations. We present those cases where LVOTO can transiently occur without hypertrophic cardiomyopathy when inotropic agents are used for hypotension.

MEASUREMENTS AND MAIN RESULTS

Five women in the 50-70 age range and prior history of hypertension presented with various symptoms like chest discomfort, fatigue, dizziness, atrial fibrillation, and hypotension. An ejection systolic murmur was noted most often in the left third intercostal space and ECG revealed ST-T wave abnormalities. LVOTO caused by mitral systolic anterior motion was detected by echocardiography and catheterization excluded acute coronary disease. In critical care setting, LVOTO can occur due to apical ballooning syndrome, coronary disease, medications, volume depletion, and valvular abnormalities. Because this condition mimics acute coronary syndrome or other etiologies of hypotension in medical and surgical intensive care units, appropriate treatment can be delayed. Nonhypertrophic cardiomyopathy LVOTO usually responds well to fluid replacement, beta blockers, and medication changes.

CONCLUSIONS

LVOTO should be suspected especially in women presenting with hypotension and systolic murmur in critical care settings. Clinical acumen and timely echocardiography are required to effectively counter this transient but potentially lethal problem.

Complications of myocardial infarction

Echocardiography is a most useful bedside tool to help in the diagnosis and management of critically ill patients after acute myocardial infarction. In most instances, the mechanism of unexplained shock will be elucidated. Transesophageal echocardiography can further delineate the mechanical complications of myocardial infarction when the transthoracic echocardiogram may not be adequate. This article will focus on the mechanical complications of myocardial infarction in patients who most often present with cardiogenic shock or acute pulmonary edema. Each clinical entity is discussed, and illustrative echocardiograms are provided.

Dynamic intraventricular obstruction in acute myocardial infarction with administration of cilostazol

Dynamic intraventricular obstruction is a less well-known mechanical complication of acute myocardial infarction (AMI). Its hallmark is the development of a new systolic murmur, and echocardiography is necessary for diagnosis. We describe a case of a 74-year-old woman with dynamic intraventricular obstruction complicating AMI. Serial echocardiography suggested that the intraventricular gradient was a consequence of basal hyperkinesis, which was a reciprocal response to akinesis of the apical wall. Cilostazol, which was administered to prevent subacute stent thrombosis after percutaneous coronary intervention, might have contributed to the transient intraventricular obstruction.

Different Effects of Propranolol, Phenylephrine, and Saline Volume Loading on Catecholamine-Induced Left Ventricular Outflow Tract Obstruction in Acute Coronary Syndrome

Hemodynamic deterioration due to left ventricular outflow tract (LVOT) obstruction can occur during catecholamine infusion in patients with acute coronary syndrome (ACS). The purpose of the present study was to compare the utility of propranolol, phenylephrine infusion, and rapid saline loading for reversal of dobutamine-induced LVOT obstruction in a canine model of ACS. ACS was induced via left anterior descending artery ligation in 21 open-chest anesthetized dogs, and LVOT obstruction, defined as an LVOT gradient > 30 mmHg, was induced by dobutamine infusion (20 to 40 microg/kg/min). Subsequently, the effects of propranolol infusion (0.7 to 1.0 microg/kg/min, n = 8), phenylephrine infusion (10 to 200 microg/kg/min, n = 7), and saline loading (200 to 400 mL/hr, n = 6) were assessed by serial hemodynamic measurements. All interventions produced significant and comparable improvements in the LVOT pressure gradient (propranolol: 60 +/- 16 to 15 +/- 12; phenylephrine: 68 +/- 15 to 12 +/- 10; saline loading: 58 +/- 18 to 22 +/- 10 mmHg; P < 0.001 for baseline versus postintervention; P = NS for comparison between interventions). Phenylephrine produced the greatest elevation in aortic pressure (propranolol: +15 +/- 13; phenylephrine: +51 +/- 36; saline loading: +15 +/- 15 mmHg; P < 0.05), while saline loading produced the greatest increase in cardiac output (propranolol: +0.05 +/- 0.12; phenylephrine: +0.28 +/- 0.37; saline loading: +0.73 +/- 0.48 L/min; P < 0.05). Propranolol was the only intervention that produced a significant decrease in diastolic pulmonary artery pressure (16 +/- 5 to 11 +/- 3 mmHg, P < 0.05). Propranolol, phenylephrine infusion, and saline volume loading were similarly effective in reversing dobutamine-induced LVOT obstruction in this canine model of ACS. However, each intervention produced different hemodynamic effects with potentially different clinical indications.

Massive Posterior Mitral Annular Calcification Causing Dynamic Left Ventricular Outflow Tract Obstruction: Mechanism and Management Implications

We report a case of massive posterior mitral annular calcification causing severe systolic anterior motion of the anterior mitral leaflet and dynamic left ventricular outflow tract obstruction. Mechanism of genesis of systolic anterior motion by this unusual mechanism is illustrated. Importance of recognizing this mechanism and its implications for surgical therapy are discussed. Our patient also had liquefaction necrosis of mitral annular calcification causing its extension into left ventricular myocardium mimicking a tumor.

[Cardiogenic shock due to dynamic left ventricular outflow tract obstruction as a mechanical complication of acute myocardial infarction]

We report the clinical case of a 77-years-old woman with cardiogenic shock caused by dynamic left ventricular outflow tract (LVOT) obstruction that appeared after anterior acute myocardial infarction. Dynamic LVOT obstruction has been reported in various circumstances aside from hypertrophic obstructive cardiomyopathy, such as acute myocardial infarction. In a patient with cardiogenic shock and a heart murmur after acute myocardial infarction, an acute mechanical complication, ventricular septal defect, and acute mitral regurgitation must be ruled out because the treatment of these conditions differs completely. We describe the diagnostic and therapeutic measures used in the diagnosis and treatment of this complication.

Dynamic left ventricular outflow obstruction: a reversible mechanical complication of acute myocardial infarction

Dynamic left ventricular outflow obstruction is a less well-known mechanical complication of acute myocardial infarction. Early diagnosis is important because initiation of proper management and avoidance of precipitating factors can lead to complete recovery. A patient is described who presented with acute myocardial infarction and in whom significant left ventricular outflow tract obstruction developed. Adequate therapy with beta blockers and calcium channel blockers led to complete resolution of the obstruction.

Anteroapical stunning and left ventricular outflow tract obstruction

Dynamic left ventricular outflow tract (LVOT) obstruction is typically observed in the setting of hypertrophic cardiomyopathy. It has also been reported with concentric LV hypertrophy, excessive sympathetic stimulation, and acute myocardial infarction. We describe 3 patients with chest discomfort after emotional stress, who had pronounced abnormalities on electrocardiograms, insignificant obstructive coronary disease and hemodynamic instability with LVOT obstruction, and regional wall motion abnormalities. Suppression of contractility with beta-blockers resulted in resolution of the gradient and in clinical improvement. On follow-up, functional recovery was excellent, and ventricular function had normalized. The conditions and mechanisms that may produce this sequence of events are discussed. The most probable scenario is that an acute ischemic insult secondary to vasospasm, LV stunning, and acute geometric remodeling produced a substrate for LVOT obstruction that was exacerbated by basal LV hypercontractility. The importance of this observation is that routine treatment of cardiogenic shock cannot be used and that conservative management results in excellent prognosis.

Dynamic left ventricular outflow tract obstruction in acute coronary syndromes: an important cause of new systolic murmur and cardiogenic shock

Dynamic left ventricular outflow tract (LVOT) obstruction has traditionally been associated with hypertrophic obstructive cardiomyopathy. Recently, acute dynamic LVOT obstruction has been described as a complication of myocardial infarction (MI). Herein the cases of 3 patients are described, all of whom presented with a systolic murmur and electrocardiographic evidence of MI. All 3 patients developed cardiogenic shock and were subsequently found by echocardiography to manifest an acute dynamic LVOT obstruction. Cardiogenic shock persisted until therapy was directed toward decreasing the degree of the dynamic LVOT obstruction. The treatment of acute coronary syndromes in the presence of a dynamic LVOT obstruction differs from the traditional treatment of acute coronary syndromes and includes the use of beta-blockers and alpha1-agonists, as well as the avoidance of therapies that aggravate the magnitude of the LVOT obstructive gradient, including nitrates, inotropic agents, and afterload reduction. The development of a systolic murmur in the setting of acute MI complicated by cardiogenic shock with only a small elevation in creatine kinase suggests the presence of a dynamic LVOT obstruction, as well as the classical mechanical complications of MI, namely, ventricular septal rupture and papillary muscle rupture. The presence of a dynamic LVOT obstruction is reliably detected by transthoracic echocardiography or by transesophageal echocardiography if transthoracic image quality is suboptimal.

The clinical impact of dynamic intraventricular obstruction during dobutamine stress echocardiography

We selected 73 consecutive patients without myocardial-infarction, hypertrophic cardiomyopathy or hypertension complaining of effort chest discomfort/dyspnoea, and/or reporting exercise ischaemic ECG changes, and submitted them to simultaneous dobutamine stress echocardiography (DSE) and 99mTc tetrofosmin SPECT (T SPECT) and to coronary angiography to evaluate the clinical impact of intraventricular obstruction (IVO) during dobutamine infusion. Sixteen patients (22%, 7 males, mean age+/-SD 63+/-8 years, group 1) developed IVO (mean CW Doppler velocity+/-SD: 3.8+/-1.0 m/s) and 57 (41 males, mean age+/-SD 63+/-10 years, group 2) did not. The two groups had similar incidence of angina and ischaemic ECG changes at exercise tolerance test. DSE did not demonstrate wall motion abnormalities in any group 1 patient while T SPECT showed a perfusion defect in the only one with coronary artery disease (CAD). DSE reproduced symptoms in a higher percentage of patients with than without IVO, while there was no statistical difference in the reproduction of ischaemic ECG changes, despite CAD prevalence was much lower in group 1. Group 1 patients remained asymptomatic on beta-blockers at 12-month follow-up. Dobutamine-induced IVO, by reproducing symptoms, suggests that IVO plays a role in the clinical setting in patients without CAD complaining of unexplained reduced effort tolerance who should undergo DSE.