Henry M. Spotnitz

Histologic analysis of transmyocardial channels: comparison of CO2 and holmium:YAG lasers.

BACKGROUNDnTransmyocardial laser revascularization using different lasers is being tested in the treatment of refractory angina. We conducted comparative analysis of the acute and chronic myocardial effects of these different lasers.nnnMETHODSnTransmyocardial channels were made in normal dog hearts with either a holmium:yttrium-aluminum garnet or a CO2 laser. Channels were examined histologically 6 to 24 hours, 2 to 3 weeks, and 6 weeks after creation.nnnRESULTSnRegardless of the laser source, the channels were occluded by thrombus within 6 to 24 hours. Subsequently, organization and neovascularization of the channel region occurred. Thermoacoustic damage was initially greater with the holmium:yttrium-aluminum garnet laser, but the channel appearances were indistinguishable from those made with the CO2 laser by 6 weeks.nnnCONCLUSIONSnHistologically, the myocardial effects of the CO2 and holmium:yttrium-aluminum garnet lasers are similar and differ predominantly in the amount of acute thermoacoustic injury. Channels are rapidly occluded by thrombus and are replaced by neovascularized collagen. This suggests that the physiologic effects of these two lasers may be similar and that mechanisms other than blood flow through chronic patent channels should be considered as contributing to the clinical benefits observed with this procedure.

Hemostatic Effectiveness of Fibrin Glue Derived from Single-Donor Fresh Frozen Plasma

Fibrin glue derived from pooled human blood is an effective sealant for high-porosity vascular grafts and a valuable topical hemostatic agent in heparinized patients. Use of this agent in the United States is prohibited because of potential transmission of hepatitis B, acquired immunodeficiency syndrome, and other serologically transmitted illnesses. We have developed a cryoprecipitation technique that allows preparation of fibrin glue from single-donor fresh frozen plasma. Use of this agent presumably entails no greater risk of disease transmission than intravenous administration of single-unit fresh frozen plasma. This report describes our early clinical experience with this material. Fibrin glue was used as a sealant for porous woven Dacron tubular prostheses and cardiovascular patches in 19 patients. The fibrin glue sealant has also been employed to control bleeding from needle holes and small anastomotic tears in 22 patients. No patient in this series had a bleeding complication from a suture line or graft treated with fibrin glue. This experience indicates that like fibrin glue from pooled blood, fibrin glue from single-donor plasma is effective as a graft sealant and topical hemostatic agent. Preparation of fibrin glue from single-donor plasma is simple and economical, and may provide cardiothoracic surgeons in the United States with a widely available, valuable hemostatic adjunct.

Structural conditions in the hypertrophied and failing heart

Hypertrophy represents a chronic adaptation of the myocardium to diastolic (volume) or systolic (pressure) loads. Resultant “eccentric” and “concentric” hypertrophy is discussed relative to ventricular compliance. The need for defined pressure-volume curves with known ventricular mass and shape in human disease is stressed. Ultrastructural constraints to normal and abnormal function are noted in terms of the sarcomere, and the physiologic features of fiber orientation in the ventricular wall and their implications for normal function are denoted. In the absence of significant qualitative changes in structure in ventricular hypertrophy, the quantitative implications of these changes are noted. As yet, little is known of the fiber orientation and connective tissue skeleton of the heart in either severe hypertrophy or severe myocardial failure with dilatation.

A 15-Year Experience With Permanent Pacemaker and Defibrillator Lead and Patch Extractions

BACKGROUNDnThe value of extraction of infected or hazardous epicardial and endocardial pacemaker and internal cardioverter defibrillator (ICD) leads is well established. Recent reviews including all leads and patches are lacking. This review describes experience with open and percutaneous techniques, including all lead types and indications.nnnMETHODSnWith Institutional Review Board approval, we reviewed charts of all adults and children undergoing extraction of permanent pacemaker and ICD leads and patches by a single operator between 1993 and 2008.nnnRESULTSnOverall, 145 leads and 7 patches were removed from 79 patients. Dwell time averaged 56.2 months. The commonest indications for extraction were infection (73.4%) or risk of lead fracture (20.3%). Most leads (84.2%) were extracted percutaneously. Removal was complete for 131 leads (86.2%) and partial in 14. Incomplete lead removal was rarely associated with clinical complications. Minor complications occurred in 6 patients (7.6%) and major complications occurred in 3 (3.8%). The major complication rate was 16.7% for the open group and 1.5% in the percutaneous group.nnnCONCLUSIONSnPacemaker and ICD infections generally respond to antibiotics, complete hardware removal, and a hardware free interval. However, these principles cannot always be invoked, and the risk of complications is likely to increase when hardware cannot be completely removed or when a hardware-free interval is unsafe or inadvisable. Percutaneous lead extraction is superior to open extraction in terms of safety and comfort, but epicardial extraction techniques remain critically important in selected patients.

Echocardiographic diagnosis of cardiac allograft rejection.

Abstract Current echocardiographic methods are promising for detection of rejection either as an increase in LV mass or a decrease in LV compliance. Both increased mass and decreased compliance during rejection may be mediated by the common mechanism of edema. Edema will appear specifically as increased wall volume in quantitative echocardiograms and, through decreased LV compliance, will be reflected in doppler-derived indices of diastolic filling. Initial difficulties with quantitative echocardiography related to image quality have largely been resolved. These have been replaced by concern for factors independent of rejection that affect LV mass, including hypertrophy due to hypertension or denervation-induced catecholamine hypersensitivity, and secondary effects of the immunosuppressive agents. An additional difficulty with quantitative echocardiography is that convenience for the patient is offset by the labor-intensive nature of planimetry-based analysis that has not yet been supplanted by fully automated methods. Diastolic function abnormalities within the early months following transplantation are indicators of acute rejection. However, their value in the long-term management of transplantation recipients may be diminished by effects of myocardial fibrosis, hypertension-induced hypertrophy, and accelerated coronary atherosclerosis. Analysis of echocardiographically derived indices of diastolic function is also a labor-intensive process that may not be economically feasible in the clinical setting. Echocardiography does have unique advantages for characterizing the functional changes accompanying late-onset chronic rejection. At the present time, echocardiographic techniques cannot replace endomyocardial biopsy; however, echocardiography can be a useful adjunct in the monitoring of patients for acute rejection. Clinical experience has demonstrated that both increased LV mass and abnormalities of doppler-derived indices of diastolic function can herald the onset of acute rejection in some patients that may be missed by standard techniques of immunological surveillance. Experience is insufficient to define whether different sensitivities of echo measurements and endomyocardial biopsy are statistical anomalies or reflect specific differences in the physiology of rejection. Similarly, it is unclear whether poor clinical results frequently seen in such instances reflect a fundamental property of the rejection episode or relatively late detection and treatment. A combined echocardiographic approach that includes measurement of LV mass, ultrasound tissue characterization, and evaluation of diastolic function would lead to further understanding of the interrelationship between the anatomical and physiological changes in the transplanted heart. The applications of echocardiography to the study of the cardiac allograft are multiple, and can be expected to increase as technology continues to improve.

Cardiac resynchronisation therapy optimisation strategies: Systematic classification, detailed analysis, minimum standards and a roadmap for development and testing

In this article an international group of CRT specialists presents a comprehensive classification system for present and future schemes for optimising CRT. This system is neutral to the measurement technology used, but focuses on little-discussed quantitative physiological requirements. We then present a rational roadmap for reliable cost-effective development and evaluation of schemes. A widely recommended approach for AV optimisation is to visually select the ideal pattern of transmitral Doppler flow. Alternatively, one could measure a variable (such as Doppler velocity time integral) and pick the highest. More complex would be to make measurements across a range of settings and fit a curve. In this report we provide clinicians with a critical approach to address any recommendations presented to them, as they may be many, indistinct and conflicting. We present a neutral scientific analysis of each scheme, and equip the reader with simple tools for critical evaluation. Optimisation protocols should deliver: (a) singularity, with only one region of optimality rather than several; (b) blinded test-retest reproducibility; (c) plausibility; (d) concordance between independent methods; and (e) transparency, with all steps open to scrutiny. This simple information is still not available for many optimisation schemes. Clinicians developing the habit of asking about each property in turn will find it easier to win now down the broad range of protocols currently promoted. Expectation of a sophisticated enquiry from the clinical community will encourage optimisation protocol-designers to focus on testing early (and cheaply) the basic properties that are vital for any chance of long term efficacy.

Transvenous pacing in infants and children with congenital heart disease

A technique for transvenous pacemaker implantation in children with complex heart disease is described. The use of small positive-fixation leads, introducers, retained guidewires, and atrial lead loops to allow for growth all have an important role in management of this often challenging problem.

Long QT syndrome due to a novel mutation in SCN5A: treatment with ICD placement at 1 month and left cardiac sympathetic denervation at 3 months of age

We describe the case of a newborn with congenital long QT syndrome, with 2:1 AV block and frequent episodes of Torsades de Pointes (TdP) requiring placement of a dual chamber ICD at 33xa0days and 3.63xa0kg, the youngest and smallest patient, thus far reported. Long QT syndrome was diagnosed due to bradycardia in the newborn nursery, with frequent episodes of TdP. The patient was initially treated with magnesium and esmolol then given lidocaine which resulted in dramatic transient normalization of the QTc with 1:1 AV nodal conduction. An attempt to transition to oral sodium channel and beta blockade was unsuccessful. An ICD was placed and dual chamber pacing was initiated which facilitated the transition to an oral medical regimen and ultimate discharge from the hospital. Soon after placement of the ICD, genetic testing revealed a novel F1473C mutation in the SCN5A gene. Episodes of TdP continued and left stellate gangliectomy was performed at 3xa0months of age. At 30xa0months follow-up, the patient has occasional, self-limited episodes of TdP and has received rare, successful, and appropriate ICD shocks.

Automatic implantable cardioverter defibrillator implantation for malignant ventricular arrhythmias associated with congential heart disease

The prognosis for patients with congenital cardiac abnormalities can be improved by surgical correction of hemodynamics. With1 or without2 surgery, sudden death from malignant ventricular arrhythmias is an important potential problem in congenital heart disease. Pharmacologic arrhythmia control may be limited by side effects, noncompliance or unreliable indexes predictive of drug efficacy. The automatic implantable cardioverter difibrillator (AICD) is a potential alternative. The incidence of arrhythmic death is <2% per year following AICD implant3 in adults with ventricular arrhythmias refractory to medical management. This success rate favors AICD therapy in selected patients with congenital heart disease. We present 4 such cases (Table I) and discuss their management.

Methods of implantable cardioverter-defibrillator-pacemaker insertion to avoid interactions

Experience with combined transvenous pacemaker and implantable cardioverter-defibrillator insertion in 21 patients is described. Special techniques are needed to avoid potentially lethal pacemaker-implantable cardioverter-defibrillator interaction. Separation between leads for the two devices should be maximized. The electrophysiologic criteria for successful device function can be met, even when some leads for both devices must be placed by a transvenous approach.