Posterolateral Myocardial Infarction Research Articles

Surgical treatment of tachyarrhythmias due to postinfarction left ventricular aneurysm with endoaneurysmorrhaphy and cryoablation

In this study, the efficacy of left ventricular (LV) endoaneurysmorrhaphy and cryoablation without intraoperative electrophysiologic mapping was evaluated in patients with postinfarction LV aneurysm and sustained ventricular tachycardia (VT). A prospective study was performed on all patients operated with malignant VT in the presence of a resectable LV aneurysm between July 1990 and February 2001. The study included 31 patients, 20 men and 11 women, with a mean age of 65.5 years (47-84). Monomorphic, polymorphic VT or ventricular fibrillation was present in all patients prospectively, and VT was incessant in 11. Twenty-six patients had an anterior, four patients had an inferior and one patient a posterolateral myocardial wall infarction. All patients had a well-limited ventricular aneurysm. Ten patients had three, eight patients two and 13 patients had single vessel coronary artery disease. Mean preoperative ejection fraction was 34.8 +/- 14.5% (8-62) and mean end-diastolic volume index was 141.5 +/- 51.8 ml/m(2) (57-288). Six patients had mitral regurgitation grade III or IV. All patients underwent extensive cryoablation at the transition zone of scar and viable tissue and LV remodelling with prosthetic patch in 26 patients. Associated procedures were CABG in 19 patients (61%) and mitral valve reconstruction in six patients (19%). Postoperative electrophysiologic study (EPS) revealed freedom from VT induction in 25 patients and inducible VT in five patients. One patient had inducible polymorphic VT. Five patients received an implantable cardioverter defibrillator (ICD) and three patients had a permanent pacemaker implanted. After a mean follow-up of 30 +/- 27 months (6-132) there was one arrhythmia-related death. There was one early hospital readmission for clinical VT and no need for late ICD implantation. In patients suffering from ventricular arrhythmias in the presence of a complicated postinfarction LV aneurysm, combined 'blind' cryoablation and endoaneurysmorrhaphy offers excellent arrhythmia control and clinical and haemodynamic outcome.

Predictors and Importance of Congestive Heart Failure in Patients with Acute Inferior Myocardial Infarction

Inferior myocardial infarction (MI) is considered to have a more favorable prognosis than anterior wall MI but includes high risk groups with increased mortality and morbidity. It is well known that congestive heart failure (CHF) complicating acute MI has poor prognosis. In this study we assessed the clinical and prognostic significance of CHF and the predictive value of the baseline demographic and clinical variables for CHF in patients with acute inferior MI. A total of 350 patients with acute inferior MI were included. In group A there were 26 patients (7.4%) with CHF, and in group B there were 324 patients (92.6%) without this complication. Baseline clinical and demographic characteristics and in-hospital complications of the groups were assessed. In group A patients were older (67.6 ± 9.5 vs 53.7 ± 10.9 years, p < 0.0001) and there were more female patients (50% vs 15%, p < 0.00001) compared to group B. The prevalence of diabetes mellitus (58% vs 16%) and precordial ST segment depression on admission ECG (81% vs 50%) were significantly higher in group A compared to group B (p < 0.00001 and p=0.002 consecutively). In group A there was a higher rate of righ ventricular (25% vs 23%), posterior (26% vs 24%) and posterolateral myocardial infarction (19% vs 14%), but the differences were not statistically different. In group A patients had significantly higher rate of second- or third-degree AV block (46% vs 8%, p < 0.00001), cardiogenic shock (35% vs 1%, p < 0.00001) and mortality (46% vs 3%, p < 0.00001) compared to group B. In a multivariate regression analysis diabetes mellitus (p=0.0003) and precordial ST segment depression on admission ECG (p=0.002) were found as the independent predictors of in-hospital CHF in patients with acute inferior MI. CHF and ST segment depression on admission ECG were found as the independent predictors of in-hospital mortality (p < 0.00001, p=0.04 consecutively). Patients with CHF complicating acute inferior MI have more unfavorable demographic and clinical characteristics on admission, higher rate of in-hospital complications and mortality. History of diabetes mellitus and precordial ST segment depression on admission ECG have an independent predictive value for CHF in this particular group of patients.

Spatio-temporal tracking of myocardial deformations with a 4-D B-spline model from tagged MRI

Accurate delineation of the volumetric motion of the left ventricle (LV) of the heart from tagged magnetic resonance imaging (MRI) is an important area of research. We have built a system that takes extracted tag line features from short axis (SA) and long axis (LA) image sequences as input and fits a four-dimensional (4-D) time-varying B-spline model to the data by simultaneously fitting the model knot solids to MRI frames via matching three sequences of solid knot planes to the LV tag planes for 4-D tracking. Important advantages of the model are that reconstruction of tag surfaces, three-dimensional (3-D) material point localization, as well as displacement reconstruction are all achieved in a single step. The generated 3-D displacement fields are validated with a cardiac motion simulator, and 3-D motion fields capturing in vivo deformations in a porcine model with posterolateral myocardial infarction are illustrated.

Does increased lipoprotein (a) impair the effectiveness of thrombolysis with streptokinase?

Although lipoprotein (a) [Lp(a)] has been shown to interfere with thrombolysis in vitro, its effects on thrombolytic therapy in patients with acute myocardial infarction (MI) are not clear. The authors evaluated 32 male patients ages thirty-five to seventy-five (mean fifty-two +/- ten) with the diagnosis of acute MI who underwent thrombolytic therapy with 1,500,000 units of intravenous streptokinase. All patients underwent coronary angiography within seven days of the infarction from which the thrombolysis in myocardial infarction (TIMI) flow grades of the infarct-related artery, coronary scores, and ejection fraction were determined. Anterior MI was found in 19 patients (59.4%), inferior MI in 12 (37.5%), and posterolateral MI in 1 patient (3.1%). They found that 6 patients (18.8%) had TIMI flow 0 to 1, and 26 patients (81.2%) had TIMI flow grade 2 or 3. The Lp(a) levels ranged from 0.1 to 60 mg/dL with a mean of 8.6 +/- 17 mg/dL. Eight (25%) of the patients had Lp(a) levels above 30 mg/dL. The TIMI flow rates were not found to be lower in patients with high Lp(a) levels (P > 0.05), and there was no significant correlation between the TIMI flow rates and the Lp(a) levels (r = 0.28). There was a good correlation between coronary scores and Lp(a) levels (r = 0.87). They conclude that although there is a good correlation between the extent of coronary atherosclerosis and Lp(a) levels, Lp(a) is not a strong predictor of the outcome of thrombolytic therapy.

A case of acute posterolateral myocardial infarction complicating complete rupture of the anterior papillary muscle and salvaged emergency mitral valve replacement

A case of acute posterolateral myocardial infarction complicating complete rupture of the anterior papillary muscle and salvaged emergency mitral valve replacement

Late Cardiac Strangulation due to an Iatrogenic Pericardial Defect

A 14-year-old boy developed broad posterolateral myocardial infarction. During cardiac surgery at age five, a small pericardial window had been made. Autopsy revealed an extensive left-sided pericardial defect and necrosis of the left ventricular free wall, which had herniated and strangulated through the enlarged pericardial defect.

Anatomic validation of electrocardiographic estimation of the size of acute or healed myocardial infarcts

Seventeen new criteria added to the simplified version of the Selvester QRS scoring system to comprise the complete version were evaluated to determine their value in estimating the size of single infarcts. These non-Q-wave criteria might be particularly useful regarding posterolateral infarcts in the distribution of the left circumflex artery. The study population was made up of 21 anterior, 30 inferior and 20 posterolateral single myocardial infarction (MI) patients with no evidences of bundle branch or fasccular blocks, ventricular hypertrophy or previous MI on their final stable electrocardiogram. The complete system's maximum 32 points is capable of indicating MI in 96% of the left ventricle and it estimated a mean electrocardiographic MI size that better approximated the anatomic size compared with the simplified version in all Ml locations. The correlation between anatomic and electrocardiographic MI size using the complete system was better and statistically significant for the posterolateral MI group (simplified r = 0.55, p <0.01 vs complete r = 0.70, p <0.0006). Criteria such as Q and S amplitude ≤0.3 mV in V 1 and ≤0.4 mV in V 2 were particularly helpful. This study documents the improved ability provided by the 17 additional non-Q-wave criteria which have been added in the complete version of this scoring system regarding the sizing of infarcts in the region of the left ventricle supplied by the left circumflex artery.

Electrocardiographic tall R waves in the right precordial leads: Comparison of recently proposed ECG and VCG criteria for distinguishing posterolateral myocardial infarction from prominent anterior forces in normal subjects

Electrocardiographic tall R waves in the right precordial leads may be present in patients with posterior myocardial infarction, right ventricular hypertrophy, various conduction disturbances, and some forms of cardiomyopathy and in clinically otherwise normal subjects with prominent anterior electromotive forces. Clinical uncertainty most often arises in distinguishing possible prior posterolateral myocardial infarction (PMI) from the unusual normal variant (PAF). The ECGs and VCGs of 15 subjects with posterolateral infarction were compared with tracings from 12 subjects with no evidence of cardiac disease, all individuals demonstrating tall R waves ( R S > 1.0 in V 1 and/or V 2) in the right precordial leads on surface ECG. By standard ECG, the infarction group was characterized by taller T waves in leads V 1 and V 2, shorter T waves in V 6, greater T2–T6 index, and a more negative two variable function as described by Nestico. By VCG, the infarction group was characterized by a more anteriorly oriented T loop, more leftward maximal frontal plane QRS vector and a lower calculated −45°/ab, as described by Suzuki. An algorithm was proposed that permitted proper classification (PAF vs. PMI) based on ECG criteria in 75% of subjects with 90% accuracy. This compared favorably with performance of the Frank vectorcardiogram, including using more recently proposed criteria. Routine use of the VCG, therefore, in this clinical setting may no longer be justified.

Myocardial infarction with normal coronary arteries complicated by rupture of the left ventricular free wall

We report the case of a 73-year-old woman successfully treated for a subacute rupture of the ventricular free wall which occurred on the fourth day after a postero-lateral myocardial infarction. Angiography performed prior to surgical repair revealed the presence of normal coronary arteries. The pathogenetic mechanism of such a happening remains uncertain, but the role of abrupt recanalization must be considered.

Dipyridamole-thallium-201 tomography documenting improved myocardial perfusion with therapy in Kawasaki disease

Thallium-201 tomographic perfusion studies after pharmacologic vasodilation were performed in seven children (aged 2 years 8 months to 8 years 7 months), 3 to 20 months after the acute stage of the disease. In all patients coronary aneurysms were seen on cross-sectional echocardiograms. The scintigrams of six children showed no significant regional reduction of myocardial thallium-201 uptake. These children had remained asymptomatic in the follow-up period after the acute inflammatory stage of Kawasaki disease. Persistent and transient thallium defects were present in one child with acute posterolateral myocardial infarction; obstruction of two coronary vessels supplying the defect zones was confirmed by contrast angiography. After 8 months of treatment a follow-up nuclear scan showed marked reduction in the size of the defect and almost complete abolishment of the ischemic reaction. Thus tomographic thallium-201 perfusion scintigraphy in conjunction with vasodilation stress is useful to assess myocardial perfusion in children with Kawasaki disease and demonstrates marked improvement in regional perfusion after adequate medical therapy.

T loop in posterior myocardial infarction: A useful clue to vectorcardiographic diagnosis

In order to differentiate posterior (posterolateral) myocardial infarction (PMI) from the anterior shift of the QRS loop in "normal variant" cases using a vectorcardiogram, the T loop as well as the QRS loop in the transverse plane (TP) were analyzed in 34 elderly Japanese males with angiographically-proven PMI and in 197 elderly Japanese males with normal coronary arteries and ventricles. T loops in the TP were longer, narrower and more anterior in PMI cases. After this analysis, we propose new criteria for PMI: (A and B) A: maximal T vector equal or anterior to 60 degrees in TP B: at least two of the following three: maximal QRS voltage/maximal T voltage in TP equal to or less than 3.0; QRS-T angle equal to or less than 75 degrees in TP; width/length of T equal to or less than 0.15 in TP. These new criteria for PMI are more specific (p less than 0.01) and more sensitive (p less than 0.05) than Hoffman's criteria.

Impending paradoxical embolism from atrial thrombus: Correct diagnosis by transesophageal echocardiography and prevention by surgery

During recovery from a posterolateral myocardial infarction, a 56 year old patient developed signs of deep vein thrombophlebitis and subsequently of pulmonary embolism. After conventional echocardiography showed masses in both atria, transesophageal two-dimensional echocardiography clearly revealed an elongated mass overriding an atrial septal defect. Impending paradoxical embolism was confirmed at surgery.

Coronary Artery Stenosis Following Aortic Valve Replacement and Intermittent Intracoronary Cardioplegia

From July, 1977, to July, 1980, intermittent cold blood potassium cardioplegia was used in 208 patients undergoing aortic valve replacement. Aortic root injection of the cardioplegic solution at 10°C was followed every 20 to 30 minutes by infusions of the solution through Silastic cannulas sutured in the coronary orifices or reinserted with each injection. Symptoms of myocardial ischemia developed in 6 patients 3 to 30 months postoperatively. Coronary angiography confirmed new stenoses of the left orifice (3 patients), left main trunk (1 patient), left anterior descending coronary artery (2 patients), circumflex coronary artery (1 patient), and right orifice (3 patients). Four patients underwent saphenous vein grafting procedures, with 2 deaths; 2 patients refused reoperation. A seventh patient with 80% stenosis of the circumflex coronary artery and a posterolateral myocardial infarction died 2 months after double-valve replacement. Intermittent cold blood potassium cardioplegia instead of continuous perfusion did not prevent coronary arterial injury. Injuries occurred in the distal coronary arteries as well as the orifices and were not prevented by withdrawal of the cannulas between injections. Tight-fitting cannulas and high-pressure injection should be avoided. A careful search for coronary arterial injury should be made in all symptomatic patients following aortic valve replacement.

Cardiogenic shock due to ventricular rupture: A surgical approach

Following a posterolateral myocardial infarction, a 57-year-old man developed severe shock which did not respond to catecholamine infusion and intra-aortic balloon counterpulsation. Implantation of a left ventricular assist pump was planned, but at sternotomy free ventricular rupture was identified and repaired. Repair of free-wall ventricular rupture is uncommon because of infrequent antemortem diagnosis. A more aggressive surgical approach of instituting left ventricular assist pumping in those patients with cardiogenic shock refractory to medical therapy and intra-aortic balloon pumping should yield the additional benefit of repair of the rather common but rarely recognized lesion of ventricular rupture.

Anterior QRS loop in hypertrophic cardiomyopathy

Frank vectorcardiograms (VCGs) were reviewed in 45 patients with hypertrophic cardiomyopathy (HCM), 26 with obstruction and 19 without obstruction. Twelve of the 19 patients without obstruction and five of the 26 patients with obstruction were found to have predominantly anterior QRS loops. Fourteen patients had a large left anterior QRS loop with increased anterior and leftward force; the posterior and terminal rightward force were within the normal range, and the T loops were displaced posteriorly and to the right opposite to the QRS loop. Asymmetric septal and apical hypertrophy were noted echocardiographically and/or angiographically. Increased electrical force from the asymmetric hypertrophy of the septal and apical area is proposed to explain this large left anterior loop. Three patients had a QRS loop located anteriorly and to the right with electrocardiograms (ECGs) resembling those of posterolateral myocardial infarction or right ventricular hypertrophy. These finding suggest that (1) hypertrophic cardiomyopathy may be another cause of an anterior QRS loop; (2) the recognition of the large left anterior loop in the VCG in patients with a left ventricular hypertrophy pattern in the ECG is helpful in the diagnosis of HCM, especially the nonobstructive form; and (3) hypertrophic cardiomyopathy should be considered in the differential diagnosis of myocardial infarction or right ventricular hypertrophy.

Abnorme myokardiale Durchblutungsverteilung nach nicht-transmuralem Infarkt

While coronary angiography was within normal limits in three patients with recurrent severe attacks of angina and non-transmural postero-lateral wall myocardial infarction, myocardial perfusion scintigraphy demonstrated an abnormal distribution pattern. In addition to recanalised thrombosis, embolism or spasm, abnormalities in the microcirculation are possible causes of the discrepancy between the coronary arteriogram and the scintigram. Myocardial perfusion scintigraphy is of particular diagnostic significance in this group of patients with coronary heart disease but normal coronary angiography. Treatment in the presence of this finding consists of administration of platelet-aggregation inhibitors.

Spontaneous reversion of ventricular fibrillation to normal sinus rhythm in a case of acute myocardial infarction

A 61-year-old white woman presented a history of advanced vascular disease of approximately fifteen years' duration, resulting from hypertensive and arteriosclerotic cardiovascular disease. Following an acute posterolateral myocardial infarction, she went into sudden collapse lasting approximately five minutes. Ventricular fibrillation was actually recorded over a period of 1 minute and 47 seconds and then spontaneously reverted to a normal sinus rhythm. Her convalescence was uneventful and she was discharged without any evidence of cerebral deterioration.

The electrocardiographic features of high posterolateral myocardial infarction.

The electrocardiographic features of high posterolateral myocardial infarction.