Elaboration of Porous Salts

A large library of novel porous salts based on charged coordination cages was synthesized via straightforward salt metathesis reactions. For these, solutions of salts of oppositely charged coordination cages are mixed to precipitate MOF-like permanently porous products where metal identity, pore size, ligand functional groups, and surface area are highly tunable. For most of these materials, the constituent cages combine in the ratios expected based on their charge. Additional studies focused on the rate of salt metathesis or reaction stoichiometry as variables to tune particle size or product composition, respectively. It is expected that the design principles outlined here will be widely applicable for the synthesis of new porous salts based on a variety of charged porous molecular precursors.

Gas Storage in Porous Molecular Materials

Molecules with permanent porosity in the solid state have been studied for decades. Porosity in these systems is governed by intrinsic pore space, as in cages or macrocycles, and extrinsic void space, created through loose, intermolecular solid-state packing. The development of permanently porous molecular materials, especially cages with organic or metal-organic composition, has seen increased interest over the past decade, and as such, incredibly high surface areas have been reported for these solids. Despite this, examples of these materials being explored for gas storage applications are relatively limited. This minireview outlines existing molecular systems that have been investigated for gas storage and highlights strategies that have been used to understand adsorption mechanisms in porous molecular materials.

Neutron diffraction structural study of CO2 binding in mixed-metal CPM-200 metal-organic frameworks

Metal-organic frameworks featuring open metal coordination sites have been widely studied for the separation of gas mixtures. For CO2/N2 separations, these materials have shown considerable promise. Herein, we report the characterization of a subset of the well-known PCN-250 class of frameworks upon CO2 adsorption via powder neutron diffraction methods. Noteably, in contrast to previously reported data, they display only moderate CO2 adsorption enthalpies, based on metal cation-CO2 interactions. Further, we show charge balance in these materials is likely achieved via ligand vacancies rather than the presence of μ3-OH groups in the trimetallic cluster that comprises them.

Understanding Gas Storage in Cuboctahedral Porous Coordination Cages

Porous molecular solids are promising materials for gas storage and gas separation applications. However, given the relative dearth of structural information concerning these materials, additional studies are vital for further understanding their properties and developing design parameters for their optimization. Here, we examine a series of isostructural cuboctahedral, paddlewheel-based coordination cages, M₂₄(^tBu-bdc)₂₄ (M = Cr, Mo, Ru; ^tBu-bdc^2- = 5-tert-butylisophthalate), for high-pressure methane storage. As the decrease in crystallinity upon activation of these porous molecular materials precludes diffraction studies, we turn to a related class of pillared coordination cage-based metal-organic frameworks, M₂₄(Me-bdc)₂₄(dabco)₆ (M = Fe, Co; Me-bdc^2- = 5-methylisophthalate; dabco = 1,4-diazabicyclo[2.2.2]octane) for neutron diffraction studies. The five porous materials display BET surface areas from 1057-1937 m²/g and total methane uptake capacities of up to 143 cm³(STP)/cm³. Both the porous cages and cage-based frameworks display methane adsorption enthalpies of -15 to -22 kJ/mol. Also supported by molecular modeling, neutron diffraction studies indicate that the triangular windows of the cage are favorable methane adsorption sites with CD₄-arene interactions between 3.7 and 4.1 Å. At both low and high loadings, two additional methane adsorption sites on the exterior surface of the cage are apparent for a total of 56 adsorption sites per cage. These results show that M₂₄L₂₄ cages are competent gas storage materials and further adsorption sites may be optimized by judicious ligand functionalization to control extracage pore space.

Design and synthesis of capped-paddlewheel-based porous coordination cages

A novel cluster capping strategy is employed to leverage the structural diversity of metal–organic cages toward the isolation of porous cages.

Methane Storage in Paddlewheel-Based Porous Coordination Cages

Although gas adsorption properties of extended three-dimensional metal-organic materials have been widely studied, they remain relatively unexplored in porous molecular systems. This is particularly the case for porous coordination cages for which surface areas are typically not reported. Herein, we report the synthesis, characterization, activation, and gas adsorption properties of a family of carbazole-based cages. The chromium analog displays a coordination cage record BET (Brunauer-Emmett-Teller) surface area of 1235 m²/g. With precise synthesis and activation procedures, two previously reported cages similarly display high surface areas. The materials exhibit high methane adsorption capacities at 65 bar with the chromium(II) cage displaying CH₄ capacities of 194 cm³/g and 148 cm³/cm³. This high uptake is a result of optimal pore design, which was confirmed via powder neutron diffraction experiments.

Gas adsorption in an isostructural series of pillared coordination cages

The synthesis and characterization of two novel pillared coordination cages is reported.

Electrophysiologic characteristics at initiation of ventricular tachycardia and ventricular fibrillation in a canine infarct model

Local ventricular activation time and the conduction time during sinus rhythm at the induction of ventricular tachycardia (VT) and ventricular fibrillation (VF) were investigated using a canine model of chronic myocardial infarction. Of 26 dogs studied, 15 had inducible VT, 10 had inducible VF, and 1 had no inducible arrhythmias. Bipolar local ventricular electrograms were recorded during sinus rhythm from 136 sites in 10 dogs with VT and 164 sites in 11 dogs with VF. Mean activation time in dogs with inducible VT was significantly longer than in dogs with inducible VF. Furthermore, simultaneous local ventricular electrograms were recorded during the induction of VT (74 episodes) or VF (38 episodes) from the infarct border zone at the endocardium (B-EN), the epicardium (B-EP), and normal sites (N-EN, N-EP). During VT induction, the activation time at N-EN and N-EP was significantly longer than during VF induction (N-EN: 94 +/- 21, 70 +/- 19 ms; N-EP: 83 +/- 21, 64 +/- 10 ms; p < 0.05). Conduction time was measured at the initiation of VT or VF induced by orthodromic or antidromic pacing. The conduction times of the last paced beat between N-EN and B-EP (35 +/- 11, 62 +/- 24 ms), N-EN and N-EP (35 +/- 12, 14 +/- 13 ms), B-EN and B-EP (16 +/- 10, 38 +/- 25 ms), and B-EP and N-EP (77 +/- 27, 44 +/- 12 ms) were significantly different in dogs with inducible VT (p < 0.05), but not in dogs with VF.(ABSTRACT TRUNCATED AT 250 WORDS)

Observations on the initiation of sustained ventricular tachycardia by programmed stimulation

We analyzed the initiation of sustained monomorphic ventricular tachycardia (VT) by programmed ventricular stimulation (PVS) in 50 consecutive patients who had clinical VT or aborted sudden cardiac death with remote myocardial infarction. In 25 of 50 patients, the first induced QRS complex of VT was morphologically identical to the succeeding QRS complexes of VT (type I). In 25 other patients, the first VT beat had a different morphology (type II). Type I had a significantly longer VT cycle length than type II (333 +/- 65 msec and 293 +/- 66 msec, P = 0.036). Type II VT initiation required more aggressive stimulation protocol than type I (type I: type II; number of extrastimulus required for induction 2.5 +/- 0.9 : 3.0 +/- 0.6, P = 0.026; shortest extrastimuli coupling interval 244 +/- 28 msec : 220 +/- 23 msec, P = 0.002). The interval between the last extrastimulus and the onset of the first VT beat was 408 +/- 88 msec in type I and 336 +/- 75 msec in type II (P = 0.004). Furthermore, there was good correlation between the VT cycle length and the interval from last extrastimulus to the onset of nonpaced beat in type I but not in type II.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of procainamide on ventricular tachycardia: relation to prolongation of refractoriness and slowing of conduction

The effect of procainamide on intraventricular conduction and refractoriness, and the prevention of induction of ventricular tachycardia (VT) were studied in 29 patients who had remote myocardial infarction and inducible sustained monomorphic VT. AFter intravenous administration of 15 mg/kg procainamide, induction of VT was suppressed in seven (24%) patients (responders), while in 22 (76%) VT was still inducible (nonresponders). The percent change in paced QRS duration at a cycle length (CL) of 400 msec produced by procainamide was significantly less in responders than in nonresponders: 29.8 +/- 3.9% versus 38.9 +/- 10.8% (p = 0.0020). The percent change in the right ventricular effective refractory period (ERP) at CLs of 600 and 400 msec was significantly greater in responders than in nonresponders: 14.6 +/- 6.9% versus 7.9 +/- 7.3% (p = 0.0414) for ERP at a CL of 600 msec and 15.1 +/- 7.0% versus 8.0 +/- 7.4% (p = 0.0386) for ERP at a CL of 400 msec. Stepwise discriminant analysis showed that greater percent increase in ERP at a CL of 400 msec and lesser percent increase in paced QRS duration at a CL of 400 msec were significantly independent markers for the responders. These findings suggest that lesser slowing of conduction and greater prolongation of refractoriness by procainamide tend to abolish reentry within the reentrant circuit. Greater slowing of conduction and lesser prolongation of refractoriness tend to stabilize a reentrant circuit, and promote the continued induction of VT.

Triphasic time dependence of prognostic markers in patients with sustained ventricular tachyarrhythmias and coronary artery disease

To characterize the time dependence of prognostic markers for arrhythmia recurrence and arrhythmic death, 81 consecutive patients with documented sustained ventricular tachycardia (VT) or fibrillation (VF) and coronary artery disease (CAD) were analyzed. During follow-up, 28 patients had arrhythmia recurrence and 15 patients had sudden or arrhythmic death. Three different hazard phases were identified by fitting piece-wise exponential function curves to the distribution of both arrhythmia recurrence and sudden/arrhythmic death. An initial phase (0 to 6 months) had an arrhythmia recurrence rate of 2.1% per month; a second low-risk phase (6 to 38 months) had a rate of 0.88%; and a late high-risk phase (greater than 38 months) had a rate of 2.2%. Sudden/arrhythmic death rates in each phase were 1.1%, 0.41%, and 1.7% per month, respectively. Separate Cox regression analyses within each phase identified the following independent predictors of arrhythmia recurrence: in the early phase, ejection fraction (EF) (p = 0.033) and VT inducibility rank (p = 0.048); and in the late phase, VT inducibility rank only (p = 0.003). Likewise, independent predictors of sudden/arrhythmic death were: in the early phase, EF (p = 0.049); and in the late phase, VT inducibility rank (p = 0.008) and previous history of congestive heart failure (p = 0.032). In CAD patients with documented sustained VT/VF, the probabilities of arrhythmia recurrence and sudden/arrhythmic death each followed a similar triphasic hazard function. Highest risk occurred in the late phase and the VT inducibility rank was predictive of late phase events, while EF was a predictor of early phase events.

Time-dependent risk of and predictors for cardiac arrest recurrence in survivors of out-of-hospital cardiac arrest with chronic coronary artery disease

One hundred one consecutive patients with chronic coronary artery disease who had survived out-of-hospital cardiac arrest in the absence of acute myocardial infarction underwent electrophysiologic evaluation and were followed prospectively. Ventricular tachyarrhythmias were inducible in 76 patients (75%) in the control state and were suppressed by antiarrhythmic drugs or surgery in 32 of the 76 patients (42%). During a mean follow-up of 27 months, cardiac arrest recurred in 21 patients: in two of the 25 patients in whom ventricular tachyarrhythmias were not inducible in the control state, three of the 32 in whom inducible ventricular tachyarrhythmias were suppressed after treatment, and 16 of the 44 in whom inducible ventricular tachyarrhythmias could not be suppressed after treatment. Actuarial rate of cardiac arrest recurrence was 11.2% during the first 6 months of follow-up ("high-risk early phase") and then decreased to less than 4% in each subsequent 6-month period. Multivariate Cox proportional hazards analysis identified an ejection fraction less than 35% (p = 0.0013) and persistent inducibility of ventricular tachyarrhythmias (p = 0.0025) as independent predictors of cardiac arrest recurrence for the entire follow-up period. Separate analysis of variables within and after the first 6 months showed that an ejection fraction less than 35% was the strongest predictor for early phase recurrence (p = 0.0078) but had only marginally significant predictive value for late phase recurrence (p = 0.0516). Persistent inducibility of ventricular tachyarrhythmias had no significant predictive value for early phase recurrence (p = 0.1382) but was the strongest predictor for late phase recurrence (p = 0.0061). These data suggest that, in patients with chronic coronary artery disease who survive out-of-hospital cardiac arrest, poor ejection fraction and persistent inducibility of ventricular tachyarrhythmias have a different predictive influence on early and late phase recurrence. Time-dependent risk factor analysis may have great clinical relevance in assessing an individual's changing risk over time.

Predictors of sustained ventricular tachycardia inducibility in patients with nonsustained ventricular tachycardia and chronic coronary artery disease

To assess the likelihood of inducing sustained ventricular tachycardia, we analyzed a cohort of 58 retrospective and 18 prospective patients with chronic coronary artery disease who underwent electrophysiologic study because of spontaneous nonsustained ventricular tachycardia (three or more beats, lasting less than 30 seconds, at a rate greater than 100/min). In 24 of the 58 retrospective patients (41%) sustained ventricular tachycardia was inducible. Stepwise logistic regression identified two "major" variables--left ventricular aneurysm/dyskinesis/akinesis (p = 0.0001; relative risk = 11.88) and ejection fraction less than 40% (p = 0.0002; relative risk = 9.69)--and one "minor" variable--nonsustained ventricular tachycardia longer than 10 beats (p = 0.0151; relative risk = 4.21)--as significant predictors of inducibility. Nineteen patients with both major variables had a high probability of inducibility (greater than 90%). Nineteen patients with neither major variable had a low probability of inducibility (less than 5%). The remaining 20 patients with only one of the major variables had an intermediate probability of inducibility (14% to 75%). The significance of the third minor factor, nonsustained ventricular tachycardia longer than 10 beats, was confined to this intermediate group, in which it could be used to segregate relatively high (65% to 75%) and relatively low (14% to 20%) probability of inducibility. Prospective application of the predictor function stratified 18 additional patients into three groups with high (six patients), intermediate (seven patients), and low (five patients) probability of inducibility. The observed rate of inducibility in each group was 5 of 6 (83%), 2 of 7 (29%), and 0 of 5 (0%), respectively. These data suggest that patients with nonsustained ventricular tachycardia and chronic coronary artery disease can be stratified into subgroups with high, intermediate, and low probability of inducibility of sustained ventricular tachycardia on the basis of ejection fraction and regional ventricular wall motion defects alone.

Cardiac syncope: a case exhibiting dichotomy between clinical impression and electrophysiologic evaluation

This case report illustrates the value of electrophysiologic study in patients presenting with graphically unmonitored syncope and/or sudden cardiac death, and who have clinical markers of both bradycardia and ventricular tachycardia. In our patient, a wide QRS on the electrocardiogram and Holter monitor documented high grade ventricular ectopic activity. In this case, had therapy been solely guided by the clinical impression that the patient had ventricular tachycardia, the treatment would have resulted in increasing the risk of recurrence of syncope and/or sudden cardiac death.

Comparison of coronary artery bypass surgery and medical therapy in patients 65 years of age or older. A nonrandomized study from the Coronary Artery Surgery Study (CASS) registry

We compared the results of coronary artery bypass surgery with those of medical therapy alone in 1491 nonrandomized patients 65 years of age or older. Cumulative survival at six years (adjusted for major differences in important base-line characteristics) was 79 per cent in the surgical group and 64 per cent in the medical group (P less than 0.0001). At five years, chest pain was absent in 62 per cent of the surgical group and 29 per cent of the medical group (P less than 0.0001). Analysis by the Cox proportional-hazards model suggested an independent beneficial effect of surgery on survival (P less than 0.0001). Patients were divided into risk quartiles on the basis of preoperative predictors of survival identified by the Cox model. Surgical benefit was greatest in "high-risk" patients (those in the two quartiles containing patients with the poorest prognosis). Among 234 "low-risk" patients with mild angina, relatively good ventricular function, and no left main coronary artery disease, there was no survival difference between those treated medically and those treated surgically. We conclude that in specific higher-risk subsets of non-randomized patients 65 years of age or older, coronary bypass surgery appeared to improve survival and symptoms in comparison with medical therapy alone. These conclusions must be tempered by consideration of the limitations of nonrandomized studies, particularly since patients in the two treatment groups differed substantially with regard to important base-line characteristics.

Externally activated antitachycardia pacemaker with noninvasive electrophysiologic re-testing capability

An Omni Orthocor 234A special device pacemaker was implanted in nine patients for treatment of drug-resistant supraventricular tachycardia (three patients) or ventricular tachycardia (six patients). This device is activated using a special external unit, which delivers from six to 15 stimuli at preselected coupling intervals ranging from 195 to 500 ms. Serial noninvasive electrophysiology studies were performed either in the hospital or on an outpatient basis using the triggered mode, which can respond to programmed chest wall stimulation. Three patients with reciprocating supraventricular tachycardia were treated effectively by this device during an average follow-up of 2.2 years. Of the six patients with stable ventricular tachycardia amenable to pacemaker termination, only four remained successful during an average follow-up of 1.9 years. Such devices may find important use in serial noninvasive electrophysiologic testing during long-term clinical follow-up. The present form of this device is inadequate for widespread application, but may be useful for highly selected individuals.

Lymphocytic myocarditis presenting as unexplained ventricular arrhythmias: diagnosis with endomyocardial biopsy and response to immunosuppression

During a period of 18 months beginning in January 1982, a total of 65 patients were referred to the Miami Heart Institute for evaluation of either aborted out of hospital sudden death, ventricular tachycardia resistant to standard clinically directed antiarrhythmic medication programs or high grade ventricular arrhythmia (Lown class greater than or equal to IV B) with or without syncope. After complete evaluation including cardiac catheterization in all but 1 patient, 17 patients were identified in whom no obvious cardiac disease could be found. Twelve of the 17 underwent right ventricular endomyocardial biopsy. Six of the 12 biopsies demonstrated clinically unsuspected lymphocytic myocarditis (Group A). Findings in three of the remaining six biopsies were consistent with an early cardiomyopathy and in three were completely normal (Group B). Retrospective review of the clinical, laboratory, electrophysiologic, hemodynamic and angiographic data failed to identify a marker that reliably separated Group A from Group B patients. In addition to antiarrhythmic therapy guided by laboratory electrophysiologic study, all Group A patients were treated with prednisone and azathioprine. After 6 months of immunosuppression, all patients with myocarditis were reevaluated in the hospital without antiarrhythmic medication. Ventricular tachycardia/fibrillation could not be provoked in the laboratory during repeat electrophysiologic testing in five of the six patients. Repeat myocardial biopsy after all immunosuppressive therapy had been discontinued revealed absence of inflammation associated with varying degrees of residual interstitial fibrosis. There were no deaths. It was concluded that a patient with an otherwise clinically silent lymphocytic myocarditis can present with potentially life-threatening ventricular arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term efficacy of percutaneous transluminal coronary angioplasty (PTCA): report from the National Heart, Lung, and Blood Institute PTCA Registry

The NHLBI PTCA Registry has collected data from 3,079 patients who underwent PTCA at 105 centers from September 1977 through September 1981 that document the initial risks and benefits of PTCA. A subgroup of 2,272 patients at 65 centers was chosen to examine the long-term effects of PTCA (97% follow-up). All patients were followed for 1 year, 191 for 3 years and 57 for 4 years. Initial success occurred in 1,397 (61%), and 72% remained improved at 1 year with no further procedures; during the first year of follow-up, 14% had repeat PTCA, 12% had CABG, 3% had MI and 1.6% died. After 1 year, 67% were asymptomatic; of these, 52% had no other procedure, 7% had a second PTCA and 8% had CABG. Follow-up at 2 to 4 years was similar except that there were few repeat PTCA or CABG procedures after 1 year. The annual mortality rate after PTCA in patients with 1-vessel diseases was less than 1% per year and with multivessel CAD, 3% per year. Thus, successful PTCA alone results in sustained improvement in 84% of patients; 59% were asymptomatic (12% had repeat PTCA). PTCA offers extended effective therapy in selected patients with CAD.

Design of comparative clinical studies of percutaneous transluminal coronary angioplasty using estimates from the Coronary Artery Surgery Study

The design of a prospective randomized trial of PTCA is discussed. It is suggested that patients with proximal subtotal occlusion of 1 or more vessels may be candidates for such a trial. Medical therapy as a control of 1-vessel CAD, medical or surgical therapy as a control for 2-vessel CAD (with 1 dilatable vessel) cases and surgical therapy as a control for 3-vessel CAD are most congruent with current practice. Possible criteria for comparison of PTCA with a control therapy include vital status, angina with daily activities, angina upon maximal exercise testing, MI, hospitalization, work status, cost, follow-up angiographic assessment, follow-up radionuclide ventriculography, measurement of immediate anatomic or hemodynamic change during initial treatment and quality-of-life indexes. These 10 measures are evaluated with respect to 9 desirable attributes for outcome criteria: the importance of the quantity measured, reproducibility, accuracy, low influence of investigator bias, low influence of subject bias, the measure is inexpensive and easy to obtain, sufficient occurrence to detect important differences, convenient to patients and measuring impairment due to disease. Examination of data from the Coronary Artery Surgery Study suggests that (1) a trial based on mortality alone is not feasible (because of a needed sample size in the thousands); (2) a trial using a combined death and/or MI end point would need approximately 1,000 cases even for patients with multivessel CAD; (3) approximately 950 patients would be needed in a trial to evaluate return to work (within 10%); (4) a trial based on pain relief (within 15% of the control group) would need 500 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-up of patients from the coronary artery surgery study (CASS) potentially suitable for percutaneous transluminal coronary angioplasty

To determine the proper place for percutaneous transluminal coronary angioplasty (PTCA) among the therapeutic options available for patients with coronary heart disease, one must compare the results of PTCA with those obtained by conventional medical and surgical therapy. To develop a cohort comparison group, we interrogated the Coronary Artery Surgery Study (CASS) registry, and patients with proximal discrete subtotal stenosis (70% to 99%) involving the right, left anterior descending, circumflex, or left main coronary artery, singly or with stenoses in two of the three major coronary arteries, were selected; 796 patients (3.7% of all patients enrolled in CASS from 1975 to 1979) met these selection criteria. Surgical therapy was chosen in 53.3%; surgical mortality was low and there was excellent 4-year actuarial survival. There was significant improvement in functional class. Survival was also excellent in medically treated patients. Medically treated patients also had significant improvement in functional class in comparison with baseline values. The data presented here characterize a cohort group against which the clinical results of PTCA can be evaluated and compared.

Macroreentry as a mechanism of atrial-induced ventricular ectopic beats: a laboratory curiosity?

During electrophysiologic study in a patient, programmed stimulation of the atrium induced fixed coupled ventricular premature beats on the basis of intraventricular macroreentry. This type of macroreentry, which was reproducible, appears to have been merely a "laboratory curiosity" and never played a clinical role in this patient with chronic recurrent ventricular tachycardia.

Percutaneous transluminal coronary angioplasty: report of complications from the National Heart, Lung, and Blood Institute PTCA Registry

The complications reported in the first 1500 patients enrolled in the National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry are analyzed. Data were contributed from 73 centers between September 1977 and April 1981. PTCA was successful in 63% of attempts. Five hundred forty-three in-hospital complications occurred in 314 patients (21%). The most frequent complications were prolonged angina in 121, myocardial infarction (MI) in 72, and coronary occlusion in 70. One hundred thirty-eight patients (9.2%) had major complications (MI, emergency surgery or in-hospital death). One hundred two patients (6.8%) required emergency surgery, usually for coronary dissection or coronary occlusion. Sixteen patients (1.1%) died in-hospital; the mortality rate was 0.85% in patients with one-vessel disease and 1.9% in those with multivessel disease. The mortality rate was significantly higher in patients who had had bypass surgery (p less than 0.001). Nonfatal complications were significantly influenced by the presence of unstable angina (p less than 0.001) and initial lesion severity greater than 90% diameter stenosis (p less than 0.001). This report delineates and assesses the complications encountered with PTCA during its initial 3 1/2-year clinical experience. These results support the relative safety of PTCA as a method of nonsurgical myocardial revascularization in carefully selected patients.

Coronary arteriography and coronary artery bypass surgery: morbidity and mortality in patients ages 65 years or older. A report from the Coronary Artery Surgery Study

Of 2144 patients age 65 years or older entered into the registry of the Coronary Artery Surgery Study (CASS) who had coronary arteriography, 1086 underwent isolated coronary artery bypass grafting. Complications of angiography included death in four patients and nonfatal myocardial infarction in 17. Eight patients suffered neurologic complications, which were transient in five. The perioperative mortality was 5.2% (57 of 1086), which is significantly greater than the perioperative mortality of 1.9% (151 of 7827) in patients younger than 65 years entered in CASS (p less than 0.001). There was a trend toward an increased mortality rate with age; it was 4.6% (37 of 803) in patients age 65-69 years, 6.6% (16 of 241) in those 70-74 years and 9.5% (four of 42) in those 75 years or older. The duration of hospital stay after operation was significantly longer for the patients 65 years or older than for the patients younger than 65 (13.3 vs 11.4 days; p less than 0.001). Stepwise linear discriminant analysis identified five variables predictive of perioperative mortality: presence of 70% or more stenosis of the left main coronary artery and a left-dominant circulation, left ventricular end-diastolic pressure, a history of current cigarette smoking, pulmonary rales on auscultation, and presence of one or more associated medical diseases. A second linear discriminant analysis, incorporating 7658 CASS patients who underwent isolated coronary artery bypass surgery irrespective of age, examined whether age 65 years or older was an independent predictor of perioperative mortality. The variables selected, in order of significance, were congestive cardiac failure score, left main coronary artery stenosis and a left-dominant circulation, age 65 years or older, left ventricular wall motion score, sex and history of unstable angina pectoris. In patients 65 years or older, the mortality from coronary arteriography is low, whereas mortality from coronary artery bypass surgery is greater than that in CASS patients younger than 65 years.

A permanently implanted endocardial electrode complicating ventricular tachycardia with a second VT

A VVI pacemaker was permanently implanted for the purpose of suppressing recurrent ventricular tachycardia (VT). Not only did the device fail to suppress the VT, but also the permanent endocardial electrode caused a second VT which was more rapid and clinically more severe. When a new VT occurs in the presence of a permanently implanted ventricular pacing system, the implanted electrode should be considered as one of the possible etiologic causes for the VT.

Aneurysmal coronary artery disease

To examine the clinical and historical features and the natural history of aneurysmal coronary disease, we reviewed the registry data of the Coronary Artery Surgery Study (CASS). Nine hundred seventy-eight patients, representing 4.9% of the total registry population, were identified as having aneurysmal disease. No significant differences were noted between aneurysmal and nonaneurysmal coronary disease patients when features such as hypertension, diabetes, lipid abnormalities, family history, cigarette consumption, incidence of documented myocardial infarction, presence and severity of angina, and presence of peripheral vascular disease were examined. In addition, no difference in 5-year medical survival was noted between these two groups. These findings suggest that aneurysmal coronary disease does not represent a distinct clinical entity but is, rather, a variant of coronary atherosclerosis.

Intrahisian functional bundle branch block

A patient with functional complete left bundle branch block is presented. The site of block was localized to the area of the His bundle. This case demonstrates that functional complete left bundle branch block may be due to longitudinal dissociation in the His bundle.

Percutaneous transluminal coronary angioplasty: report from the Registry of the National Heart, Lung, and Blood Institute

Data have been collected from 34 centers in the United States and Europe performing percutaneous transluminal coronary angioplasty since September 1977. The procedure was carried out in 631 patients, with an average age of 51 years (range 23 to 76), of whom 80 percent had single vessel coronary disease, 17 percent had double or triple vessel disease and 3 percent had stenosis of the left main coronary artery. Coronary angioplasty was successful (greater than 20 percent decrease of coronary stenosis) in 59 percent of the stenosed arteries. The mean degree of stenosis was reduced from 83 to 31 percent. Emergency coronary bypass operation was required in 40 patients (6 percent). Myocardial infarction occurred in 29 patients (4 percent). In-hospital death occurred in six patients (1 percent), three with single vessel and three with multivessel disease. Ninety-one patients have been followed up for at least 1 year after coronary angioplasty. Of the 65 patients with an initially successful angioplasty, 83 percent were in improved condition compared with their status before angioplasty. Thus, the initial satisfactory results obtained in a few centers have now been confirmed in many centers using transluminal coronary angioplasty.

Interobserver variability in interpreting contrast left ventriculograms (CASS)

Randomly selected left ventricular cineangiograms performed by 14 medical centers (clinical sites) participating in a large multicenter study of medical and surgical treatment of coronary artery disease (CASS) were systematically recalled and reread by one of four designated quality control centers. The end diastolic volume (EDV), end systolic volume (ESV), and ejection fraction (EF) calculated by the quality control center were compared with those calculated by the clinical site, and correlation coefficients of 0.71, 0.84, and 0.79, respectively, were obtained. Regional left ventricular (LV) wall motion abnormalities were assessed by dividing the LV wall as viewed in the right anterior oblique (RAO) and left anterior oblique (LAO) views into five segments each and grading the motion of each segment according to six categories of increasing abnormalities from normal to aneurysm. When discrepancies based on "nearest neighbor" differences in naming adjacent segments were eliminated and only marked differences of more than one degree of severity of wall motion abnormality were considered, interobserver differences were 7% and 10% for RAO and LAO segments, respectively. Agreement was less frequent in designating a segment "aneurysmal." When each LV segment was assigned a numerical score based on increasing severity of wall motion abnormality and a total LV score for each ventriculogram computed, the quality control and clinical site readings were in good agreement with a correlation coefficient of 0.83.

Guidelines for effective and safe percutaneous intraaortic balloon pump insertion and removal

During the 12 month period beginning February 1980, a total of 54 consecutive patients had 60 attempts at percutaneous insertion of an intraaortic balloon because of medically uncontrollable angina, cardiogenic shock either in the setting of an acute myocardial infarction or within hours of cardiac surgery and as a prophylactic measure in high risk patients before cardiac surgery. The balloon was successfully inserted in 49 patients (91 percent). In five patients the balloon could not be inserted in spite of eight attempts because of tortuosity of the iliac artery. All nine patients in whom balloon insertion was attempted without fluoroscopy had the device inserted successfully. The four insertion attempts during cardiac massage were all successful. Experience with use of the new longer introducer sheath is described. Since its acquisition there has not been a single balloon pump insertion failure in 20 consecutive patients including 6 patients in whom initial attempts through the conventional short death were unsuccessful because of iliac tortuosity. The major complications encountered in the present series were thromboembolic: femoral arterial thrombosis developed in five patients (10.2 percent) and an asymptomatic pulse loss in the contralateral foot developed in another. There were no cases of pseudoaneurysm, groin hematoma, aortic dissection or infection related to the percutaneous balloon. On the basis of this experience, several guidelines are suggested for safe and effective percutaneous insertions and removal of the intraaortic balloon pump.

Should this patient be paced? An indication for His bundle study: syncope, a normal P-R interval and a narrow QRS

This report describes a patient who presented with transient central nervous system symptoms of unknown etiology with an electro-cardiogram exhibiting a narrow QRS complex and normal. P-R interval. The decision to implant a permanent VII pacemaker was made on the basis of a His bundle study that revealed significant prolongation of the HV interval. The successful clinical outcome re-emphasizes the clinical usefulness of electrophysiological investigation in patients with syncope of undetermined etiology.

Safe transthoracic left ventricular puncture performed with echocardiographic guidance

Retrograde aortic left ventricular pressure recording is difficult to obtain and often unreliable in the presence of a mechanical aortic valve prosthesis. Under echocardiographic guidance, we have safely performed transthoracic left ventricular puncture for pressure recording in seven patients with an aortic valve prosthesis. The transducer is placed at the left sternal border and then slid laterally until the right ventricular cavity and interventricular septal echoes disappear, but before the echoes from the left lung are recorded. The chest wall is marked and the transducer is angled until the mitral valve echoes are identified. The transducer angle and direction are recorded with external markers, and the left ventricular cavity depth is measured. An 18-gauge needle is then inserted the determined depth into the left ventricle, guided exactly by the echocardiographic external markers. The procedure was successful in each patient on the first attempt without a single complication. We conclude that this technique affords the operator greater control when left ventricular pressure must be recorded by transthoracic puncture and that it may reduce the risk of potentially serious complications.

Complications of coronary arteriography from the Collaborative Study of Coronary Artery Surgery (CASS)

Data were collected prospectively on 7553 consecutive patients undergoing coronary arteriography. The studies were performed at 13 clinics of the Collaborative Study of Coronary Artery Surgery (CASS) using brachial and femoral techniques. There were eight deaths 0--24 hours and seven deaths 24--48 hours after arteriography (2/1000). There were 15 non-fatal myocardial infarctions (MIs) 0--24 hours and four MIs 24--48 hours after arteriography (2.5/1000). Of 657 cases with left main stenosis greater than or equal to 50%, five died and three had MI. Left main disease increased risk of death by 6.8 times (p less than 0.001). Other factors increasing risk were unstable angina, congestive heart failure, multiple premature ventricular contractions, and hypertension. Of the 1187 patients studied from the brachial artery, six died (0.51%) and five had MIs (0.42%). In 6328 patients studied from the femoral artery, nine died (0.14%) and 14 had MIs (0.22%). The brachial artery technique increased the risk of death 3.6 times compared with the femoral approach (p less than 0.05). This result did not apply when analysis was restricted to laboratories with 80% or more brachial procedures. Risk was not altered by heparin. Thus, a prospective, multicenter analysis of complications reveals low risk of coronary arteriography but significant difference between two techniques.

An unusual form of the bradycardia-tachycardia syndrome: paroxysmal A-V block and ventricular tachycardia

An unusual case of alternating bradycardia-tachycardia, paroxysmal Mobitz II A-V block and ventricular tachycardia is described. The patient presented with a normal resting (control) electrocardiogram and intracardiac conduction times (A-H and H-V intervals). The clinical evaluation, electrophysiology, and importance of defining the cause of serious rhythm disturbances prior to therapy are discussed.

On-line computer storage, retrieval, and reporting of coded angiographic data

Interpretations of angiographic images have been coded and stored using an on-line computer terminal for seven years. Decoded angiographic information is incorporated in computer-generated reports which are printed on demand after completion of cardiac catheterization procedures. Currently, almost 5,500 cases are stored in an off-line data base which has been designed to help identify patterns with prognostic potential. Also, the program has helped standardize angiographic nomenclature, saved much clerical time, and virtually eliminated clerical errors. The program interacts with other software in the hospital, avoiding repetitious entries. The advantages and shortcomings of the program and commonly used approaches to computer storage/retrieval of radiographic information are described.

Obscure syncope and the sick sinus syndrome

This report describes a 25-year-old vigorous young man who had a history of eight years of near syncope and syncope of unknown etiology. Repeat in-hospital observation and laboratory electrophysiologic functional testing did not elucidate the origin of the symptoms. Prolonged Holter monitoring finally showed that the syncopal attacks were caused by a sick sinus syndrome (SSS). On electrophysiologic study, a concealed rate-dependent unidirectional antegrade accessory A-V pathway (AP) was found to be present. The AP was an incidental finding and was unrelated to the patient's symptoms. The symptomatic SSS may occur in the young as well as in the elderly. Sinoatrial dysfunction may be intermittent and difficult to detect, may cause severe symptoms, and may even be life-threatening. Prior to definitive therapy (such as the permanent implantation of a pacemaker), the importance of relating symptoms to a rhythm disturbance has been stressed. In cases where the cause of the symptoms is not obvious, this is best accomplished by continuous Holter monitoring.

Sodium nitroprusside as a coronary vasodilator in man. I. Effect of intracoronary sodium nitroprusside on coronary arteries, angina pectoris, and coronary blood flow

The effect of the intra-arterial injection of 5 to 10 microng of sodium nitroprusside on the caliber of normal and diseased coronary arteries was evaluated in 21 patients during diagnostic cardiac catheterization. In addition, the effect of intra-graft injection of 5 microng of the same agent on the blood flow in aorta-right coronary artery saphenous vein bypass grafts was also evaluated intra-operatively in two patients. The compound induced an increase in the caliber of both normal and stenosed coronary arteries as well as an increase of flow in the grafts. Consistent with measurements of coronary flow response to sodium nitroprusside, angina pectoris which developed in four patients during cardiac catheterization was immediately relieved and the ischemic ST-segment depression significantly reversed after injection of 5 to 10 microng of the drug into the left main coronary artery. Within the dose range used, the drug caused no significant effect on systemic blood pressure or apparently deleterious electrophysiologic changes. No side effects were observed. We conclude that the primary direct action of sodium nitroprusside in the human coronary artery is vasodilatory.

Sodium nitroprusside as a coronary vasodilator in man: a comparison of the effects of sodium nitroprusside and papaverine hydrochloride on aortocoronary saphenous vein graft flow

Blood flow in aortocoronary saphenous vein grafts was studied in response to intragraft injection of sodium nitroprusside and papaverine hydrochloride. Following injection of 50 mug of sodium nitroprusside, mean graft flow increased from 40.1 +/- 4.5 to 81.3 +/- 8.5 ml per minute. Administration of 30 mg of papaverine hydrochloride caused mean graft flow to rise from 35.4 +/- 3.9 to 70 +/- 7.9 ml per minute. Sodium nitroprusside increases aortocoronary graft flow, the doubling effect of 50 mug of the drug being of the same order of magnitude as that induced by 30 mg of papaverine hydrochloride.

Antiarrhythmic activity of four pteridine compounds in ouabain intoxication

The antiarrhythmic effects of 4 pteridine analogues, 2 of which are potassium-sparing diuretics, triamterene (2, 4, 7-triamino-6-phenylpteridine) and [2-phenyl-4, 7 diaminopteridine-6-(N-diethylaminoethyl) carboxamide] and 2 of which have no diuretic effects [2-phenyl-4, 7-diaminopteridine-6-(N-2-hydroxyethyl) carboxamide], on ouabain-induced ventricular tachycardia in intact pentobarbital-anesthetized dogs were investigated. Ouabain was given as a continuous infusion 2 mug/kg/min intravenously until 5 min after the onset of a sustained ventricular tachycardia. It was found that both 6-(N-dimethylaminopropyl) and 6-(N-diethylaminoethyl) carboxamide derivates of the pteridine had a significant protective effect against ouabain-induced ventricular tachycardia in dogs that had been pretreated with a dose of 5 mg/kg intravenously. At this dose the 2 pteridine compounds with diuretic activity exhibited a transient antiarrhythmic effect in abolishing the ouabain-induced ventricular tachycardia while those without diuretic properties failed to suppress the ventricular tachycardia.