Intracoronary streptokinase thrombolytic recanalization and subsequent surgical bypass of remaining atherosclerotic stenosis in acute myocardial infarction: Complementary combined approach effecting reduced infarct size,preventing reinfarction,and improving left ventricular function

In 48 patients with acute myocardial infarction (AMI) the acutely thrombus-occluded coronary artery was successfully recanalized nonsurgically via catheter with intracoronary streptokinase (SK) infusion after a mean occlusion time of 3.1 ± 1.6 hours. In all cases residual high-grade fixed atherosclerotic stenosis remained after percutaneous transluminal coronary recanalization (PTCR). Subsequent aortocoronary bypass surgery (ACBS) circumventing the stenotic coronary artery was performed during the acute stage of myocardial infarction (within 10 days of AMI onset) in 34 patients and electively (longer than 10 days after AMI onset) in 14 patients. No patient died from early PTCR or from ACBS intervention. There were two late post-ACBS arrhythmogenic deaths, two patients suffered nonfatal reinfarction post ACBS several months after hospital discharge, only two had occasional post-ACBS angina pectoris, and one patient had post-ACBS mild heart failure. The remaining 41 post-ACBS patients were completely asymptomatic throughout long-term follow-up evaluation. In the left ventricular (LV) segment supplied by the initially occluded coronary artery, which was recanalized early by means of SK therapy and subsequently grafted, wall motion improved significantly from the acute to the postoperative stage in patients who underwent early surgery (from 13.6% ± 1.9% to 40.3% ± 2.7%, p < 0.001) and in the electively operated group (from 18.0% ± 7.1% to 48.2% ± 6.3%, p < 0.001). Ischemic wall motion was improved irrespective of whether or not the bypass graft circumventing the residual stenosis of the infarct vessel remained patent. Wall motion of nonischemic segments remained essentially unchanged. In the patients who underwent surgery in the early stage, the closure rate of the bypass graft to the infarct-related vessel was 17%, and in the electively operated group no graft was found to be occluded. In conclusion, coronary artery recanalization, achieved by means of early SK-PTCR therapy with subsequent ACBS, can be performed safely in patients with AMI, and the result will be marked improvement in LV segmental wall motion and global function, diminished reinfarction rate, and reduced incidence of angina pectoris, all benefits that are consistently maintained during long-term evaluation.     

Coronary artery reperfusion in acute myocardial infarction: Beneficial effects of intracoronary streptokinase on left ventricular salvage and performance

Coronary angiography was performed on hospital admission in 37 patients with acute myocardial infarction (AMI). Thirty patients had total occlusion of the infarct-related coronary artery and seven patients had severe proximal stenoses with poor distal flow. In 20 of 30 patients with total occlusion, intracoronary (IC) infusion of streptokinase (SK) resulted in reperfusion of the distal coronary artery. Left ventricular (LV) performance was assessed before coronary angiography and at discharge from the hospital by use of gated cardiac blood pool imaging techniques. In patients evidencing reperfusion of the infarct-related coronary artery, mean (± SD) left ventricular ejection fraction (LVEF) increased from admission through discharge (46% ± 15% to 55% ± 10%, p = 0.002). In contrast, LVEF did not change from admission through discharge in patients with severe proximal stenoses alone or in patients with total occlusion who did not demonstrate reperfusion following SK administration (47% ± 17% vs 49% ± 18%, p = ns). In an additional 14 control patients with AMI who were not evaluated with coronary angiography, LVEF did not change from admission through discharge (46% ± 12% vs 48% ± 14%, p = ns). Quantitative thallium-201 perfusion imaging demonstrated an increase (p < 0.05) in thallium uptake in the infarct segment following coronary artery reperfusion. In contrast, thallium uptake did not change (p = ns) in the infarct segment in patients not evidencing angiographic coronary artery reperfusion. These data support the following: (1) Coronary artery thrombus occurs frequently in AMI and can be lysed by IC SK, and (2) reperfusion with IC SK in patients with evolving myocardial infarction results in myocardial salvage and improved LV performance through hospital discharge.     

Aneurysmectomy and endocardial resection for ventricular tachycardia: Favorable hemodynamic and antiarrhythmic results in patients with global left ventricular dysfunction

Sixty-two patients underwent aneurysmectomy and endocardial resection for control of recurrent sustained ventricular tachycardia (VT). Forty patients also had coronary artery bypass grafting (CABG) (1.5 grafts per patient). The mean preoperative left ventricular end-diastolic pressure (LVEDP) was 18 ± 8 mm Hg, cardiac index (Cl) was 2.7 ± 0.7 L/min/m², and ejection fraction (EF) was 28 ± 10%. In a subset of 32 patients with clearly demarcated aneurysmal and contracting ventricular sections, the mean EF of the residual contracting section (CSEF) was 35 ± 13%, and 26 of these patients had a CSEF < 45%. There were five operative deaths (8%). No hemodynamic findings distinguished the patients who died during surgery. Patients with an LVEDP above the group mean or an overall EF below the group mean had an operative mortality of 10% and 7%, respectively. In the subgroup of 26 patients with a CSEF < 45%, the operative mortality was 12%. In the surgical survivors as a whole the LVEDP decreased from 17 ± 8 to 14 ± 5 mm Hg (p < 0.005) and the overall EF increased from 28 ± 9% to 39 ± 10% (p < 0.001) while the normal CI did not change. Linear regression analysis revealed that patients with the highest preoperative LVEDPs and the lowest overall EFs were most likely to have improvement in these parameters postoperatively. Patients with a preoperative CSEF < 45% had similar postoperative changes in their LVEDP (17 ± 6 to 15 ± 4 mm Hg) and overall EF (24 ± 7% to 38 ± 11%). In addition, the incidence of inducible VT postoperatively was similar in patients with a preoperative CSEF < 45% (4 of 23) and in the rest of the group (8 of 34, p = NS). We conclude that: (1) patients with ventricular aneurysms and medically refractory VT often have marked dysfunction of the residual contracting LV section; (2) aneurysmectomy and endocardial resection is an effective mode of therapy for VT and can be performed with a low operative mortality in this patient population; and (3) postoperatively the angiographic EF usually increases and the LVEDP often decreases, especially in patients with the most marked preoperative LV dysfunction.     

Sequential postoperative assessment of left ventricular performance with gated cardiac blood pool imaging following aortocoronary bypass surgery

The comparative effects of normothermic intermittent ischemic arrest (IIA) and cardioplegia (C) on left ventricular (LV) performance were assessed by gated cardiac blood pool imaging in 57 patients undergoing aortocoronary bypass surgery. In 34 patients, IIA was employed; 23 patients received C. Patients were studied preoperatively, sequentially in the immediate postoperative period at 30-minute intervals, and at 1 week after the operation. C and IIA groups did not differ in mean (± SEM) age, anginal class, number of diseased vessels, previous myocardial infarction, or preoperative ejection fraction (EF) (50 ± 3% vs 50 ± 2% [p = ns]). Aortic cross clamp time was greater with C than IIA (50 ± 5 minutes vs 28 ± 3 minutes [p = 0.001]). During the six sequential postoperative studies, transient LV dysfunction (≥ 7% decrease in absolute EF) was observed in 10 patients receiving C and in 16 patients receiving IIA. By time of discharge, 24 of 26 patients had returned to preoperative EF. Mean EF at discharge in the cardioplegia group did not differ compared to preoperative EF; in the IIA group, EF increased compared to preoperative EF (50 ± 2% vs 55 ± 2% [p < 0.01]). These data suggest that in patients with normal preoperative LV performance both C and IIA afford satisfactory myocardial preservation during aortocoronary bypass surgery.     

Effect of thrombolysis (streptokinase) on left ventricular function during acute myocardial infarction

One hundred ninety-two consecutive patients with acute myocardial infarction were enrolled in a prospective trial of coronary thrombolysis in which either intracoronary or intravenous streptokinase was administered. First-pass radionuclide ejection fraction (EF) was measured early (within 24 hours of admission) and late (10 to 14 days after admission) to assess changes in left ventricular (LV) function. In 68 patients in whom reperfusion was successful, mean EF increased from 39 +/- 11% early to 47 +/- 13% late. In 36 patients in whom reperfusion was not successful, the mean EF increase was significantly smaller (from 38 +/- 10% to 42 +/- 11%, p less than 0.025). Patients in whom reperfusion was successful were then grouped according to extent of LV functional change. The extent of EF change (delta EF) was not significantly influenced by time to lysis at intervals up to 7 hours (delta EF = 9.1 +/- 10% at 2 to 3 hours, 8.7 +/- 12% at 3 to 4 hours, 10 +/- 10% at 4 to 5 hours, and 7.0 +/- 10% at 5 to 7 hours; difference not significant [NS]), location of the infarct (delta EF = 8.9 +/- 11% for inferior and 5.7 +/- 8.0% for anterior, NS), or presence of Q waves on the initial electrocardiogram (delta EF = 8.8 +/- 11% in patients with and 7.8 +/- 9.9% in patients without Q waves). Only the initial EF was predictive of subsequent EF change.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of left ventricular size on mitral E point to ventricular septal separation in assessment of cardiac performance

Increased mitral valve E point to ventricular septal separation (EPSS) is widely used as an echocardiographic index of depressed left ventricular (LV) ejection traction (EF), yet LV size has not been examined as an independent variable potentially affecting EPSS. Accordingly, we studied the relationship between EPSS and functionally normal or depressed LV with or without increased enddiastolic dimensions (EDD). Twenty normal controls had EPSS 3.2 ± 2.2 mm (mean ± SD), EDD 47 ± 5 mm, $\text{EPSS}\text{EDD}$ (“normalized” EPSS) 0.07 ± 0.04, and fractional shortening (FS%) 38 ± 6%. Nine patients with pure chronic mitral regurgitation had dilated LV (EDD = 65 ± 7 mm) with normal LV function (FS% 41 ± 5%; angiographic EF 62 ± 9%); eight patients had dilated cardiomyopathy (EDD 69 ± 8 mm) with decreased LV function (FS% 16 ± 7%; angiographic EF 32 ± 8%); and eight patients with amyloid cardiomyopathy had nondilated LV (EDD 42 ± 5 mm) with decreased LV function (FS% 19 ± 6; angiographic EF 35 ± 7%). Mitral E point to ventricular septal separation and $\text{EPSS}\text{EDD}$ accurately separated individuals with normal and abnormal LV function irrespective of LV size (χ² = 36.7; p < 0.00001). Increased internal dimensions per se did not affect EPSS unless depressed LV function coexisted. EPSS is therefore a valid predictor of depressed ejection phase indices independent of LV size.     

Effects of intracoronary streptokinase in acute myocardial infarction

Intracoronary streptokinase (SK) was administered to 11 patients with evolving acute transmural myocardial infarction 5.5 ± 0.4 hours from the onset of symptoms. Ten patients (91%) had total coronary occlusion, and one had subocclusion of the vessel corresponding to the ECG site of infarction. Intracoronary nitroglycerin failed to restore patency of total occlusion in all patients. In 9 of 11 patients (82%), patency was restored or improved with intracoronary SK. Thrombolysis was successful in 8 of 11 patients (73%), and one patient with transient patency developed acute reocclusion. Average time from SK infusion to reperfusion was 24 ± 7 minutes. Patients with successful thrombolysis had patency initially restored at a dosage of 61,000 ± 15,000 IU of SK and received a total dosage of 136,000 ± 17,000 IU. Patency persisted at late study in six of eight patients, and two patients developed late reocclusion. Successful thrombolysis was associated with significant improvement in left ventricular ejection fraction (LVEF) from early to late study, in contrast to deterioration of LVEF in patients with unsuccessful recanalization (p < 0.001). Systemic fibrinolytic activity occurred in 8 of 11 patients at a mean dosage of 125,000 ± 15,000 IU of SK and was unassociated with significant bleeding. Significant decrease in hemoglobin concentration in the early hospital phase occurred in patients receiving SK but did not differ from decreases occurring in a matched control population receiving conventional therapy for infarction. Thus intracoronary thrombolysis with SK was successful in the majority of patients during the early phase of evolving transmural infarction, and successful thrombolysis was associated with significant improvement in LVEF. Systemic fibrinolysis occurs in most patients despite small total doses of SK, and the significant decrease in hemoglobin in these patients may be unrelated to SK, since similar changes occurred in a control population receiving conventional therapy.     

Immediate detection of early high-risk patients with acute myocardial infarction using two-dimensional echocardiographic evaluation of left ventricular regional wall motion abnormalities

Forty-three patients with acute myocardial infarction (AMI) were studied with serial two-dimensional echocardiography (2DE) to define a high-risk subset for in-hospital cardiovascular complications including pump failure, life-threatening arrhythmias, or death. A 2DE segment score was developed representing the extent of left ventricular (LV) regional wall motion abnormality (WMA) which was correlated with peak total creatine kinase (CK) release. Patients with transmural AMI had a segment score of 7.2 ± 3.8, whereas those with nontransmural AMI had a segment score of 4.7 ± 3.4 (p < 0.025). Peak total serum CK enzyme level correlated statistically with segment score but with a low correlation coefficient. Thirteen (30%) of the 43 patients had an in-hospital complication and their segment score was 10.0 ± 3.4 compared to 4.6 ± 2.7 in those patients without a complication (p < 0.005). A segment score ≥ 8 was found in 11 of 13 (85%) of those who suffered a cardiac complication and in only five (16%) of the 30 patients without complication (p < 0.05; sensitivity 85%, specificity 83%). Patient's initial clinical Killip classification was specific but very insensitive in predicting an early complicated course. Thus, 2DE study of LV regional wall motion can predict in the immediate post-AMI stage the in-hospital likelihood of such patients developing a cardiovascular complication during acute myocardial infarction.     

Effects of lidocaine on regional intraventricular conduction in patients with coronary artery disease

Studies of isolated heart muscle and canine models of myocardial ischemia have demonstrated that lidocaine slows conduction in abnormal but not in normal tissues. To determine lidocaine's effects on intraventricular conduction (IVENT) in patients with coronary artery disease (CAD), we studied this agent in seven patients following left anterior descending coronary artery (LAD) bypass surgery. Epicardial electrodes were placed on the right atrium, left ventricle (LV) in the distribution of the LAD, and on the right ventricle (RV). On postoperative day 7, lidocaine was administered as 100 mg bolus followed by 4 mg/minute infusion for 2 hours. At constant atrially paced rate, bipolar electrograms were recorded from the LV and RV for the 2 hours of infusion and for 2 hours after discontinuation of infusion. Conduction intervals were measured from the earliest onset of QRS in three simultaneously recorded surface ECG leads to the major deflection of the electrogram from each ventricle. At peak effect, with mean lidocaine level of 2.7 ± 0.5 mg/ml, lidocaine slowed LV conduction by a mean of 6 ± 1 msec (14 ± 2%) (p < 0.001) and in the RV by 1 ± 0.3 msec (4 ± 1%) (p < 0.01). QRS duration changed 1 ± 1 msec (1 ± 1%) (NS). The values returned to baseline within 2 hours after discontinuation of lidocaine infusion. The difference in lidocalne's effect between the diseased LV and the normal RV was significant (p < 0.001).     

Detection and assessment of severity of regional ischemic left ventricular dysfunction by digital fluoroscopy

Digital intravenous ventriculography (DIV) was used to detect and assess the severity of regional and global left ventricular (LV) function in the presence of graded levels of coronary stenosis. DIV was performed on six anesthetized dogs with a coronary blood flow probe and micrometer controlled occluder on the circumflex coronary artery (CXA) and pairs of sonic dimension crystals in the posterointerior (ischemic area) and anterior (control area) walls of the LV in the control state, with subtotal occlusion of the CXA (STEN), and with CXA occlusion (OCL). Global analysis at each stage included area-length calculation of end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF). Regional analysis included calculation of area displaced by anterior wall (AA), and posteroinferior wall (IA), average amplitude of excursion of the anterior wall (AE), and posteroinferior wall (IE). STEN caused significant increase in AA (14.4 ± 2.2%) and decreases in EF (?19.7 ± 2.5%), IA (?36.6 ± 4.2%), and IE (?30.8 ± 5.3%) (p < 0.05). With OCL, there were significant increases in EDV (78.7 ± 7.6%), ESV (225 ± 20.6%), AA (42.6 ± 10.3%), and AE (25.5 ± 4.3%); with further fall in EF (?42.4 ± 2.1%), IA (?94.3 ± 6.6%), and IE (?84.7 ± 9.4%) (p < 0.01). Regional functional indices derived from DIV detected regional wall motion abnormalities, when these were shown to be present by sonocardiometer measurements of myocardial segment length and extent of shortening in the ischemic region of the LV. We conclude that DIV is a sensitive technique for the detection and assessment of severity of regional and global LV dysfunction in ischemic heart disease.     

Cardiocirculatory and myocardial energetic effects of prostaglandin E1 in severe left ventricular failure due to chronic coronary heart disease

The cardiocirculatory actions of brief (69 ± 5 minutes) infusions of prostaglandin E₁ were evaluated in nine chronic coronary heart disease patients with severe left ventricular (LV) failure caused by previous myocardial infarction. Prostaglandin E₁ infusion did not alter heart rate (HR) and produced modest declines in mean systemic blood pressure (BP) (85 ± 6 to 76 ± 5 mm Hg, p < 0.025) and LV filling pressure (19 ± 3 to 15 ± 2 mm Hg, p < 0.01). Simultaneously, prostaglandin E₁ augmented LV pump function raising cardiac index from 1.9 ± 0.2 to 2.5 ± 0.2 L/min/m² (p < 0.005), elevating stroke index from 28 ± 2.4 to 35 ± 2.9 ml/beat/m² (p < 0.01), and increasing stroke work index from 26 ± 4.3 to 30 ± 4.4 gm·m/m² (p < 0.02). Additionally, total systemic vascular resistance decreased from 1862 ± 192 to 1282 ± 100 dynes-sec-cm^?5 (p < 0.02) and double product LV aerobic index of HR · systolic BP diminished from 9492 ± 666 to 8278 ± 493 (p < 0.02). Concomitantly, in the forearm, vascular resistance fell, blood flow rose, and venous tone remained unchanged. These results indicate that prostaglandin E₁ is a potent systemic arteriolar dilator with markedly beneficial effects on cardiac function in chronic coronary patients having severe ischemic LV failure refractory to conventional therapy.     

Rotational Atherectomy for Severely Calcified Lesions in Patients With Left Ventricular Systolic Dysfunction: One-Year Outcomes From aSingle-Center Registry Analysis

BackgroundHigh-risk percutaneous coronary intervention (PCI) in patients with left ventricular (LV) systolic dysfunction has been proven to induce reverse LV remodeling. However, the impact of high-risk PCI focusing on rotational atherectomy (RA) in patients with severe LV systolic dysfunction has not been completely addressed.MethodsAmong 4339 consecutive patients who underwent PCI, 178 patients with 192 lesions were treated with RA. The reduced ejection fraction (EF) group (LVEF ≤35%) included 25 patients, the mid-range EF group (LVEF 36–50%) included 44 patients, and the preserved EF group (LVEF >50%) included 109 patients. The primary outcome was a composite of cardiac death, non-fatal myocardial infarction, target-vessel revascularization, and ischemic stroke.ResultsThe cumulative 1-year incidence of the primary outcome was similar among the three groups (reduced EF, 29%; mid-range EF, 25%; preserved EF, 26%; p = 0.95). After adjusting for confounding factors, the incidence of the primary outcome in the reduced EF group (hazard ratio [HR], 1.07; 95% confidence interval [CI], 0.43–2.37; p = 0.87) and the mid-range EF group (HR, 0.99; 95% CI, 0.47–1.94; p = 0.97) was similar to that in the preserved EF group. LVEF was significantly improved in the reduced EF and mid-range EF groups compared with the preserved EF group (absolute change in LVEF: 13.6 ± 11.3%, 9.0 ± 10.1%, and −0.7 ± 7.8%, respectively; p < 0.0001).ConclusionsReduced EF was not associated with increase in the primary outcome in patients undergoing RA. This seemed to result from the improved LV function after PCI.Summary for annotated table of contentsThis single center analysis study investigated 1-year composite outcome of cardiac death, non-fatal myocardial infarction, target-vessel revascularization, and ischemic stroke in patients with severe LV systolic dysfunction undergoing RA compared with that in patients with preserved LV function. The cumulative 1-year incidence of the composite outcome was similar among the three groups (reduced EF, 29%; mid-range EF, 25%; preserved EF, 26%; p = 0.95). LVEF was significantly improved in the reduced EF and mid-range EF groups compared with the preserved EF group (absolute change in LVEF: 13.6 ± 11.3%, 9.0 ± 10.1%, and −0.7 ± 7.8%, respectively; p < 0.0001).     

Radionuclide ejection fraction and regional wall motion during atrial pacing in stable angina pectoris: Comparison with metabolic and hemodynamic parameters

To evaluate the effects of atrial pacing on radionuclide (RNA) ejection fraction (EF) and regional wall motion (RWM), transmyocardial lactate gradients and hemodynamics in stable coronary artery disease (CAD), 12 CAD patients underwent incremental atrial pacing during cardiac catheterization. EF declined from 0.60 ± 0.07 during control state to 0.51 ± 0.11 (p < 0.001) during submaximal pacing (Sub Max P) with 10 of 12 having decreased EF, six developing new RWM abnormalities, and five experiencing mild chest pain. During maximal pacing (Max P), EF declined further to 0.47 ± 0.10 (p < 0.001), with all patients having decreased EF and experiencing moderate to severe chest pain, and nine developing new RWM abnormalities. Percentage lactate extraction (Ex) decreased from +28.3 ± 9.4% to +17.4 ± 11.9% during Sub Max P (p < 0.01), with only one patient producing lactate. During Max P, percentage lactate Ex decreased to ?0.1 ± 15.3% (p < 0.001) with eight patients producing lactate. Significant increases in pulmonary capillary wedge pressure and systemic vascular resistance occurred during Max P, and in mean pulmonary artery pressure and mean systemic arterial pressure during both Sub Max and Max P. Significant decreases in stroke volume index and stroke work index occurred during both pacing levels and cardiac index did not change with pacing. This study demonstrates that RNA may be used to establish decreases in EF and RWM which occur in response to incremental atrial pacing in patients with stable CAD, and that these changes are more consistent and appear earlier than the metabolic consequences of myocardial ischemia induced by pacing stress.     

Left ventricular function assessment after aortic and renal intervention in Takayasu arteritis by speckle tracking echocardiography: A pilot study

BackgroundOvert left ventricular (LV) dysfunction and congestive heart failure are known entities in Takayasu arteritis (TA). Subclinical LV dysfunction may develop in these patients despite normal LV ejection fraction (LVEF). Moreover, effect of treatment of aortic or renal artery narrowing in such patients is unknown.MethodsThis study included 15 angiographically confirmed TA patients undergoing aortic and/or renal intervention. A comprehensive clinical, biochemical and echocardiographic (2-dimensional, speckle tracking and tissue doppler imaging) evaluation were done at baseline, 72 h, and six months post intervention.ResultsSix patients (40%) had reduced LVEF (<50%) at baseline while rest 9 (60%) patients had reduced global longitudinal strain (GLS) but normal EF. Diastolic filling pattern was abnormal in all the patients. In patients with baseline reduced EF, mean EF improved from 24.62 ± 12.14% to 45.6 ± 9.45% (p = 0.001), E/e’ ratio decreased from 15.15 ± 3.19 to 10.8 ± 2.56 (p = 0.005) and median NT pro BNP decreased from 1673 pg/ml (970–2401 pg/ml) to 80 pg/ml (40–354 pg/ml) (p = 0.001) at 6 months after interventional procedure. In patients with baseline normal EF, median NT pro BNP decreased from 512 pg/ml (80–898.5 pg/ml) to 34 pg/ml (29–70.8 pg/ml) (p < 0.01), mean GLS improved from ?8.80 ± 0.77% to ?16.3 ± 0.78% (p < 0.001) and mean E/e’ decreased from 12.93 ± 2.63 to 7.8 ± 2.73 (p = 0.005) at 6 months follow up.ConclusionLV dysfunction is common in patients with TA and obstructive lesions in aorta or renal arteries. GLS can be used to assess subclinical systolic dysfunction in these patients. Timely intervention can improve LV dysfunction and can even reverse the subclinical changes.     

Alteration of left ventricular performance by left bundle branch block simulated with atrioventricular sequential pacing

The effects of atrioventricular (AV) sequential pacing-induced left bundle branch block (LBBB) on left ventricular (LV) performance were evaluated during cardiac catheterization in 9 randomly selected patients being investigated for chest pain. All patients were in normal sinus rhythm with a normal P-R interval and QRS duration. LV performance was assessed by both hemodynamic and angiographie measurements. The maximal rate of LV pressure increase (dP/dt), rate of maximal LV pressure decrease ($\text{?dP}\text{dt}$), LV end-diastolic pressure (LVEDP), end-diastolic volume (LVEDV), end-systolic volume (LVESV), stroke volume and percent ejection (EF) were measured during right atrial and AV sequential pacing at a constant pacing rate. The average pacing rate was 97 ± 3 beats/min (mean ± standard error of the mean). In each patient, both dP/dt and $\text{?}\text{dP}\text{dt}$ decreased significantly (p < 0.001) during AV sequential pacing compared with atrial pacing at the same rate, from 1,541 ± 68 to 1,319 ± 56 mm Hg/s for dP/dt and from 1,506 ± 86 to 1,276 ± 92 for $\text{?dP}\text{dt}$. LVEDP did not change significantly when atrial (17 ± 3 mm Hg) and AV sequential pacing (16 ± 2 mm Hg) were compared. Mean LVEDV did not change during atrial (135 ± 13 ml) or AV sequential pacing (137 ± 14 ml). In contrast, the LVESV during AV sequential pacing was higher by 15 ml (23 % ) (from 48 ± 10 to 63 ± 12 ml) (p < 0.001); as a result, the stroke volume was lower by 13 ml (15%) and the EF decreased by 10 %, from 66 to 56 % (?15 %).These changes in LV performance during acutely induced LBBB by AV sequential pacing as compared with atrial pacing at the same rate were independent of altered preload, because both LVEDP and LVEDV were similar during the 2 different pacing modes. Peak systolic pressure during AV sequential pacing was significantly lower than that during atrial pacing (161 ± 10 vs 145 ± 10 mm Hg, p < 0.01), and thus afterload was presumably altered during the different pacing modes. However, because the observed change in systolic pressure (afterload) was lower during AV sequential pacing, this change should improve rather than result in deterioration of ejection phase indexes. Because the opposite was observed, it is concluded the deterioration in LV function noted during AV sequential pacing must be due in part to the asynchronous pattern of ventricular activation induced by this intervention.     

Biventricular function in sickle-cell anemia: Radionuclide angiographic and thallium-201 scintigraphic evaluation

Left ventricular (LV) and right ventricular (RV) function were evaluated at rest and during exercise using radionuclide ventriculography in 10 patients, aged 19–53 years, with sickle-cell anemia (SCA). Seven patients were in New York Heart Association functional class I and 3 were in class II. The resting LV ejection fraction (EF) was normal in 9 patients and the resting RVEF was normal in 4. LV dilation and high cardiac output were observed in 6 patients at rest. The LVEF during exercise was normal in all 10 patients, whereas only 2 patients had normal RVEF at rest and during exercise. The LVEF was lower in patients with SCA at rest (54 ± 4 % versus 61 ± 6%, p < 0.001) and exercise (66 ± 4% versus 74 ± 6%, p < 0.001) than in 42 age-matched normal subjects. Rest thallium-201 images from 9 patients showed abnormal RV uptake in 8 and normal LV uptake in 8.Thus, in adult patients with SCA, LV function was normal during exercise in all patients and at rest in all but 1 patient. The LVEF, however, was lower than that in age-matched normal subjects. RV function was abnormal in most patients at rest and during exercise. RV thallium-201 uptake suggested pressure or volume overload (or both), most likely due to pulmonary vaso-occlusive complications of the disease.     

Correlation between changes in R wave amplitude and left ventricular volume induced by rapid atrial pacing

To examine the Brody effect in humans, we studied 15 patients by means of coronary sinus pacing. We measured left ventricular (LV) volumes from the cardiac output (measured by the thermodilution technique) and LV ejection fraction (measured by radionuclide ventriculography). Pulmonary blood volume was determined by means of cardiac output and mean pulmonary transit time. In six patients, pacing was performed at two different rates, resulting in 21 pacing measurements. The heart rate increased with pacing from 73 ± 11 to 119 ± 19 bpm (mean ± standard deviation, p < 0.001). The end-diastolic volume (EDV) and the end-systolic volume (ESV) decreased with pacing (p < 0.001 each). The R wave amplitude decreased with pacing (1.44 ± 0.63 mV control vs 1.32 ± 0.58 mV with pacing; p < 0.01). R wave amplitude decreased in 19 of the 21 pacing studies (90%); EDV and ESV decreased in all 21 pacing studies, and pulmonary blood volume decreased in 14 of the 15 pacing studies (93%) performed in 11 patients. There was a significant correlation between the percentage of change in R wave amplitude with the percentage of change in EDV (r = 0.54, p < 0.01) and with the percentage of change in ESV (r = 0.54, p < 0.01). These results, therefore, validate Brody's hypothesis and indicate that changes in LV volumes affect the R wave amplitude.     

Reproducibility of equilibrium radionuclide ventriculography in patients with coronary artery disease: Response of left ventricular ejection fraction and regional wall motion to supine bicycle exercise

To evaluate the reproducibility of ejection fraction (EF) and regional wall motion (RWM) analyses by rest and exercise equilibrium radionuclide ventriculography (RNV) in the presence of coronary artery disease (CAD), 18 patients underwent two maximum, multistage supine bicycle exercise studies separated by an interval of 2 weeks. There were no significant differences in EF between the two studies, both at rest (56.0 ± 13.8% vs 58.2 ± 11.7%, p = NS) and with exercise (51.1 ± 17.6% vs 54.3 ± 17.6%, p = NS) and a highly significant correlation was shown between the two groups of values (rest r = 0.90, exercise r = 0.93, p < 0.001). There was no significant difference in the change from rest to exercise (?4.9 ± 12.0% vs ?3.8 ± 11.5%, p = NS) between the two studies and the correlation was highly significant (r = 0.69, p < 0.01). The interstudy variabilities were 2.2 ± 6.1% and 1.2 ± 7.3% for rest and exercise, respectively, and 2.0 ± 9.2% for the change from rest to exercise. Ninety-four percent of both rest and exercise regions had similar RWM. Eighty-one percent of the abnormally contracting regions were common to both exercise studies. Utilizing conventional criteria for the diagnosis of CAD, 11 patients had abnormal EF response and nine had abnormal RWM response to exercise on both studies. Combining EF and RWM criteria resulted in the diagnosis of CAD in 15 patients in both studies. We conclude that: (1) there were no significant differences in rest and exercise radionuclide EF and RWM between two supine bicycle exercise studies performed 2 weeks apart in patients with stable CAD and there were significant correlations between the two studies; (2) despite these correlations, the interstudy variabilities emphasize the need for the inclusion of reproducibility studies in all evaluations of interventions by exercise radionuclide ventriculography; and (3) the variations in EF and RWM response to exercise result in a lack of uniformity between the two studies regarding the diagnosis of CAD based on conventional RNV criteria.     

Ischemia-induced impairment of left ventricular relaxation: Relation to reduced diastolic filling rates of the left ventricle

An investigation was performed in order to better define the cause of reduced diastolic filling rates of the left ventricle (LV) observed in the setting of acute myocardial ischemia. Seven closed chest, anesthetized pigs were instrumented by placing a micromanometer-tip catheter in the LV and a balloon tip catheter in the midportion of the left anterior descending coronary (LAD) artery. The animal's red blood cells were labeled with technetium-99m and LV time-activity curves obtained by means of a computer-controlled, nonimaging cardiac probe (collimated, 3.5 cm DIA, sodium iodide crystal). Nuclear data obtained simultaneously with LV pressure data were used to evaluate diastolic pressure-count rate (i.e., volume) relations of the LV under control conditions and at 5 and 10 minutes after balloon occlusion of the animal's LAD. Diastolic filling rates, the time constant (“T”) of ventricular relaxation, the chamber passive stiffness constant (“K”), and maximum negative left ventricular $\text{DP}\text{DT}$ were computed for each experimental condition. Maximum negative $\text{DP}\text{DT}$ decreased compared with control (1690 + 699 mm Hg/sec; mean ± 1 SD) at both 5 minutes (1040 ± 493, p < 0.01) and 10 minutes (1360 ± 588, p < 0.05) after occlusion. Likewise “T” was prolonged versus control (45.3 ± 6.4) at both 5 minutes (56.8 ± 12.8, p < 0.01) and 10 minutes (54.0 ± 8.7, p < 0.05) after occlusion. In contrast both “K” and calculated left ventricular pressure at zero counts (i.e., volume) remained constant throughout the study. Left ventricular end-diastolic pressure also did not change significantly during the study. The mean, maximal, and mid to late LV diastolic filling rates all were prolonged significantly (p < 0.05) versus control at 5 minutes and 10 minutes after occlusion. The rate of early diastolic filling of the LV did not change significantly during the study, although it tended to decline along with the other rates. Thus, ischemia-induced changes in diastolic filling rates may be seen in the absence of changes in left ventricular chamber stiffness, and ischemia-induced impairment of left ventricular relaxation alone is sufficient to reduce the rate of diastolic filling of the LV.     

Recovery of Myocardial Perfusion in Acute Myocardial Infarction After Successful Balloon Angioplasty and Stent Placement in the Infarct-Related Coronary Artery

Objectives. This study sought to investigate changes in myocardial perfusion after direct percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (MI).Background. After initially successful recanalization of the infarct-related artery, coronary perfusion may deteriorate as a result of reocclusion, distal embolization of platelet aggregates formed at the dilated plaque or microvascular reperfusion injury. This change could offset the benefit from early intervention.Methods. The study included 19 patients in whom the infarct-related artery was successfully recanalized by PTCA with Palmaz-Schatz stent placement within 24 h after the onset of pain. Basal and papaverine-induced coronary blood flow were assessed by Doppler flow velocity measurements and quantitative coronary angiography. In addition, basal and adenosine-induced myocardial blood flow were measured by nitrogen-13 ammonia positron emission tomography (PET).Results. Immediately after completion of the intervention, the average coronary flow reserve (CR) in the recanalized vessel was 1.56 ± 0.51; it increased to 2.04 ± 0.65 at 1 h (p = 0.013) and to 2.66 ± 0.72 at 2 weeks after reperfusion (p = 0.008, n = 16). PET studies in 12 patients revealed that perfusion defect size and CR in the infarct region (2.19 ± 0.89 vs. 2.33 ± 0.86) did not change significantly between day 2 after recanalization and 2 weeks. However, we found significant (p < 0.03) increases in basal (by 26%) and adenosine-induced (by 40%) blood flow in the infarct region.Conclusions. Despite the persistence of a perfusion defect after successful recanalization of the occluded artery in acute MI, CR of the infarct region improves in most patients within 1 h and further improves within 2 weeks.