Berry M. van Gelder

Fractional Flow Reserve A Useful Index to Evaluate the Influence of an Epicardial Coronary Stenosis on Myocardial Blood Flow

BACKGROUND Fractional flow reserve (FFR), defined as the ratio of maximum flow in the presence of a stenosis to normal maximum flow, is a lesion-specific index of stenosis severity that can be calculated by simultaneous measurement of mean arterial, distal coronary, and central venous pressure (Pa, Pd, and Pv, respectively), during pharmacological vasodilation. The aims of this study were to define ranges of FFR values, whether associated with inducible ischemia or not, and to investigate FFR in normal coronary arteries. METHODS AND RESULTS In 60 patients accepted for percutaneous transluminal coronary angioplasty (PTCA) of single-vessel disease, with a positive exercise test (ET) < 24 hours before PTCA, FFR was determined during adenosine-induced hyperemia just before and 15 minutes after angioplasty. Pa was measured by the guiding catheter, Pd by an 0.018-in fiber-optic pressure-monitoring wire, and Pv, by a multipurpose catheter. The ET was repeated after 5 to 7 days, and only if this second ET had reverted to normal was the pre-PTCA value of FFR definitely considered to be associated with inducible ischemia and the post-PTCA value not. Myocardial FFR (FFRmyo) increased from 0.53 +/- 0.15 before PTCA to 0.88 +/- 0.07 after PTCA. Coronary FFR increased from 0.38 +/- 0.19 to 0.83 +/- 0.12. In all patients, values of FFRmyo definitely associated with ischemia were < or = 0.74, whereas all except two values not associated with inducible ischemia exceeded 0.74. Moreover, FFRmyo in 18 coronary arteries in 5 normal patients equaled 0.98 +/- 0.03. CONCLUSIONS A value of FFRmyo of 0.74 reliably discriminates coronary stenosis, whether associated with inducible ischemia or not. Therefore, FFRmyo is a useful index to determine the functional significance of an epicardial coronary stenosis and may facilitate clinical decision making in patients with an equivocal coronary stenosis.

Quantification of recruitable coronary collateral blood flow in conscious humans and its potential to predict future ischemic events

OBJECTIVES The present study was designed to evaluate the applicability of a pressure-flow equation for quantitative calculation of recruitable collateral blood flow at coronary artery occlusion in conscious patients and to investigate the value of that index to predict future ischemic events. BACKGROUND Recent experimental studies have indicated that recruitable collateral blood flow at coronary artery occlusion can be expressed as a fraction of normal maximal myocardial blood flow by simultaneous recordings of mean arterial, coronary wedge and central venous pressures, respectively. This index is called the pressure-derived fractional collateral flow and is independent of hemodynamic loading conditions. METHODS In 120 patients undergoing elective coronary angioplasty, mean arterial, coronary wedge and central venous pressures were measured at balloon inflations of 2 min. All patients had a recent exercise electrocardiogram (ECG) with positive findings showing clearly distinguishable, reversible ECG abnormalities, enabling recognition of ischemia at balloon inflation. Fractional collateral blood flow at angioplasty was calculated by coronary wedge pressure minus central venous pressure divided by mean arterial pressure minus central venous pressure and correlated to the presence or absence of ischemia at balloon inflation. Ischemic events were monitored during a follow-up period of 6 to 22 months. RESULTS In 90 of the 120 patients, ischemia was present at balloon inflation, and in 82 of these patients, fractional collateral blood flow was < or = 23%. By contrast, in 29 patients, no ischemia was present, and fractional collateral blood flow was > 24% in all 29. During the follow-up period, 16 patients had an ischemic event. Fifteen of these 16 patients were in the group with insufficient collateral flow (p < 0.05). CONCLUSIONS To our knowledge, this study presents the first method for quantitative assessment of recruitable collateral blood flow in humans in the catheterization laboratory. Sufficient and insufficient collateral circulation can be reliably distinguished by this method. Use of this method can also help to provide more insight into the extent and behavior of the collateral circulation for investigational purposes and may have potential clinical implications.

Fractional Flow Reserve

The potential benefit of revascularization depends on the presence and extent of myocardial ischemia. Performing percutaneous coronary intervention (PCI) on ischemia-inducing coronary stenoses improves both symptoms and outcome, while performing PCI on non-ischemia-inducing stenoses has no benefit and is potentially harmful. Noninvasive testing and the coronary angiogram have limited ability to distinguish specific ischemic territories and responsible stenoses, especially in multivessel coronary disease. To overcome these shortcomings, fractional flow reserve (FFR) has been developed as a stenosis-specific index to determine whether a coronary stenosis has ischemic potential. FFR-guided PCI improves both symptoms and outcome. As such, knowledge of coronary physiology and FFR has become imperative in daily coronary decision making.

Diagnosis and management of inadvertently placed pacing and ICD leads in the left ventricle: a multicenter experience and review of the literature.

Three patients from different centers with pacemaker or ICD leads endocardially implanted in the left ventricle are described. All leads, two ventricular pacing leads and one ICD lead, were inserted through a patent foramen ovale or an atrial septum defect. The diagnosis was made 9 months. 14 months, and 16 years, respectively, after implantation. All patients had right bundle branch block configuration during ventricular pacing. Chest X ray was suggestive of a left‐sided positioned lead except in the ICD patient. Diagnosis was confirmed with echocardiography in all patients. One patient with a ventricular pacing lead presented with a transient ischcmic attack at 1‐month postimplantation. During surgical repair of the atrial septum defect 14 months later, the lead was extracted and thrombus was attached to the lead despite therapy with aspirin. The other patients were asymptomatic without anticoagulation (9 months and 16 years after implant). No thrombus was present on the ICD lead at the time of the cardiac transplantation in one patient. We reviewed 27 patients with permanent leads described in the literature. Ten patients experienced thromboembolic complications, including three of ten patients on antiplatelet therapy. The lead was removed in six patients, anticoagulation with warfarin was effective for secondary prevention in the four remaining patients. In the asymptomatic patients, the lead was removed in five patients. In the remaining patients, 1 patient was on warfarin, 2 were on antiplatelet therapy, and in 3 patients the medication was unknown. After malposition was diagnosed, three additional patients were treated with warfarin. In conclusion, if timely removal of a malpositioned lead in the left ventricle is not preformed, lifelong anticoagulation with warfarin can be recommended as the first choice therapy and lead extraction reserved in case of failure or during concomitant surgery.

Mechanical discoordination rather than dyssynchrony predicts reverse remodeling upon cardiac resynchronization

By current guidelines a considerable part of the patients selected for cardiac resynchronization therapy (CRT) do not respond to the therapy. We hypothesized that mechanical discoordination [opposite strain within the left ventricular (LV) wall] predicts reversal of LV remodeling upon CRT better than mechanical dyssynchrony. MRI tagging images were acquired in CRT candidates (n = 19) and in healthy control subjects (n = 9). Circumferential strain (epsilon(cc)) was determined in 160 regions. From epsilon(cc) signals we derived 1) an index of mechanical discoordination [internal stretch fraction (ISF), defined as the ratio of stretch to shortening during ejection] and 2) indexes of mechanical dyssynchrony: the 10-90% width of time to onset of shortening, time to peak shortening, and end-systolic strain. LV end-diastolic volume (LVEDV), end-systolic volume (LVESV), and ejection fraction (LVEF) were determined before and after 3 mo of CRT. Responders were defined as those patients in whom LVESV decreased by >15%. In responders (n = 10), CRT increased LVEF and decreased LVEDV and LVESV (11 +/- 6%, 21 +/- 16%, and 30 +/- 16%, respectively) significantly more (P < 0.05) than in nonresponders (1 +/- 6%, 3 +/- 4%, and 5 +/- 10%, respectively). Among mechanical indexes, only ISF was different between responders and nonresponders (0.53 +/- 0.25 vs. 0.31 +/- 0.16; P < 0.05). In patients with ISF >0.4 (n = 10), LVESV decreased by 31 +/- 18% vs. 5 +/- 11% in patients with ISF <0.4 (P < 0.05). We conclude that mechanical discoordination, as estimated from ISF, is a better predictor of reverse remodeling after CRT than differences in time to onset and time to peak shortening. Therefore, discoordination rather than dyssynchrony appears to reflect the reserve contractile capacity that can be recruited by CRT.

Extraction of pacemaker and implantable cardioverter defibrillator leads: patient and lead characteristics in relation to the requirement of extraction tools.

BRACKE, F., et al.: Extraction of Pacemaker and Implantable Cardioverter Defibrillator Leads: Patient and Lead Characteristics in Relation to the Requirement of Extraction Tools. Effective tools for extraction of pacemaker and ICD leads have been developed in the past decennium. This study investigated the necessity of using these tools in addition to direct traction in relation to patient and lead characteristics. The study encompasses first attempts at extraction of consecutive pacemaker and ICD leads from the subpectoral area. A stepwise extraction protocol was used with traction first (directly or with a locking stylet) followed by laser sheath extraction if not successful. The indication, patient age, time from implant, fixation mechanism, location, and insertion site of the leads were studied in relation to the outcome of traction. A total of 145 leads in 83 patients were extracted. Leads were implanted for 71 ± 61 months. Indication for extraction was infection in 96 leads and malfunction in 49 leads. There were 90 ventricular leads including 16 ICD leads. Forty‐nine (34%) leads were extracted with traction; in 96 (66%) leads a laser sheath was necessary. All leads implanted for < 6 months could be removed with traction alone. In a multivariate logistic regression model, time from implant was the main factor determining success of traction (P < 0.001), but in case of infection the success rate increased (P = 0.004). In conclusion, time from implant is the decisive factor to judge the potential efficacy of lead extraction with direct traction. If leads are implanted for 6 months, the availability of additional extraction tools is necessary when lead extraction is considered. In addition to time from implant, infected leads have a better chance to be removed with traction although it is a much weaker predictor.

Venous occlusion of the access vein in patients referred for lead extraction: influence of patient and lead characteristics.

The aim of this study was to determine the effect of patient and lead characteristics on occlusion of the access vein in pacemaker and ICD patients. Contrast venography of the access vein was obtained in 89 patients (17 patients with an ICD) scheduled for lead extraction. The indication for extraction was infection in 57 patients (systemic infection in 9) and lead malfunction in 32 patients. In 6 of the 89 patients, leads were introduced in both the right and left subpectoral area, resulting in a total of 95 venous entry sites. In 22 of these entry sites one lead was present, in 61 two leads, in 11 three, and in 1 four leads. The vessel patency was graded open or occluded. Occlusion of the subclavian vein occurred in four (13%) patients with lead malfunction versus 18 (32%) patients with infection (P = 0.07). In patients with systemic infection, 5 of 9 showed venous occlusion (P = 0.01 when compared to patients with malfunction, odds ratio 8.75, 95% confidence interval 1.21–64.11). Considered per entry site, the incidence of occlusion was 7 of 22 with one lead present, 17 of 61 with two leads, 0 of 11 with three leads, and 0 of 1 with four leads (P = 0.13). No patient had a superior vena caval occlusion. Patients with systemic infection have an increased risk of occlusion of the access vein. On the contrary, the study found no support for the concept that the risk of venous occlusion increases with a higher number of leads present. (PACE 2003; 26:1649–1652)

Baseline left ventricular dP/dtmax rather than the acute improvement in dP/dtmax predicts clinical outcome in patients with cardiac resynchronization therapy.

The maximum rate of left ventricular (LV) pressure rise (dP/dtmax) has been used to assess the acute haemodynamic effect of cardiac resynchronization therapy (CRT). We tested the hypothesis that LV dP/dtmax predicts long‐term clinical outcome after initiation of CRT.

Learning Curve Characteristics of Pacing Lead Extraction with a Laser Sheath

The learning curve characteristics of lead extraction with a laser sheath were examined in 19 patients. Forty‐two leads were removed: five leads were removed by traction alone, five required a femoral approach as a primary procedure and a laser sheath was used in 32 lead extraction attempts. Primary laser success was achieved in 26 attempts (81 %). A femoral approach was successfully applied as a back‐up procedure in five of the failures. Overall, 26% of the leads were removed by the femoral approach. The overall success rate was 98% (41 of 42 leads). No variables related to the patients, leads, or extraction techniques were significantly related to failure of laser sheath extraction. There was a distinct learning curve with all but one failure occurring in the first half of our cases. All failures occurred with leads implanted from the right subclavian vein. In four, a sharply angled curve at the subclavian vein‐superior vena cava junction could not be passed with the laser sheath. The ability to smooth this curve improved the results during the learning curve. All procedures were performed in the operating room for safety reasons. This precaution was lifesaving in a case of acute tamponade after laser extraction of an atrial lead. In another case the left internal mammary artery was torn after laser sheath extraction, causing the formation of a false aneurysm. New pacing leads were introduced in nine patients during the same procedure. The mean procedure time was 255 ± 110 min. reflecting the complexity of these procedures.

Clinical characteristics and coronary angiographic findings of patients with unstable angina, acute myocardial infarction, and survivors of sudden ischemic death occurring during and after sport

The clinical characteristics and coronary angiographic findings of 42 well-conditioned subjects with an acute ischemic event related to sport are reported. Five patients had unstable angina, 25 had acute myocardial infarction (AMI), and 12 were resuscitated victims of sudden ischemic death. Twenty-two events occurred during sport (group A) and 20 after sport (group B). There were two women and 40 men. The mean age was 46 years (range 25 to 65). Twelve out of 30 patients who smoked cigarettes had an adjunctive risk factor for coronary artery disease. Twelve others (28%) had no identifiable risk factor. Prodromal cardiac symptoms were detected in three patients (group A). Two patients had previous myocardial infarction (group B). Coronary angiography was performed acutely in 39 patients. The distribution of the ischemia-related coronary artery was comparable in both groups. The lesion morphology of 35 culprit coronary arteries was described as concentric in six patients and eccentric with regular borders (type I lesion) in 11 and irregular borders (type II lesion) in 18. Eccentric lesions consistent with ruptured plaques prevailed in both groups. Associated coronary artery disease was present in 10 patients. There was no relationship between the number of risk factors and the extent of diseased coronary arteries. Clinical characteristics and coronary angiographic findings of patients with unstable angina, AMI, and sudden death either during or after sport are similar and indicate a common pathogenesis. The probable mechanism of a coronary event related to sport is exercise-induced plaque rupture. In most instances such an event is unexpected and unpredictable. Identification of some subjects at risk is possible.