Reply to the editor

We appreciate the comments and concerns expressed by Arakawa and colleagues regarding our article, titled “Pulsatile control of rotary blood pumps: Does the modulation waveform matter?”1 Unfortunately, we have to disagree with Arakawa and colleagues. As is obvious from the title of our article, it investigates the effect of different waveforms on the heart–device interaction. In contrast to the authors' claim, this is the first article in the literature that uses basic waveforms (sine, triangle, saw tooth, and rectangular) with different phase shifts to examines their impact on left ventricular unloading. The previous publications2, 3 and 4 just varied the pump speed during systole and diastole, which was first reported by Bearnson and associates5 in 1996, and studied its effect on aortic pressure, coronary flow, and end-diastolic volume. We should mention that dp/dtmax is a load-sensitive parameter of contractility and not representative for the degree of unloading. Moreover, none of the aforementioned reports has studied mechanical unloading and in particular the stroke work of the left ventricle. Our method is unique because we do not just alternate between high and low speed but have accurate control of the waveform because of the direct drive system of Levitronix Technologies LLC (Waltham, Mass) and a custom-developed pump controller. Without referring, Arakawa and associates state “several previous studies have already reported the coronary flow diminishes as the left ventricular assist device support increases.” It should be noted that all the waveforms used in our study have 2000 rpm average value with 1000 rpm amplitude, which is not an excessive speed for the CentriMag rotary pump (Levitronix) to collapse the ventricle and diminish the coronary flow. We agree with Arakawa and coworkers that there is a need for a heart failure model to come to more relevant results with respect to clinical expectations. However, we have explored many existing models, including species and breeds that have a native proneness to cardiomyopathy, but all of them differ from the genetic presentation in humans. We certainly do not believe that the use of microembolization, in which the coronary circulation is impaired by the injection of microspheres, would form a good model from which to draw conclusions about coronary flow change under different loading conditions. A model would be needed in which either an infarct is created to mimic ischemic heart failure or the coronary circulation remains untouched to simulate, for instance, dilated cardiomyopathy. Furthermore, in discussion we clearly mention that “lack of heart failure is a major limitation of our study.” We also believe that unloading is not the only factor of the cardiac functional recovery, and an excessive unloading of the left ventricle might lead to cardiac tissue atrophy. Therefore, in our article we mention that control of the level of cardiac unloading by assist devices has been suggested as a mechanical tool to promote recovery, and more studies are required to find better strategies for the speed modulation of rotary pumps and to achieve an optimal heart load control to enhance myocardial recovery. Finally, there are many publications about pulsing rotary blood pumps and it was impossible to include them all. We preferred to reference some of the earlier basic works such as an original research by Bearnson and coworkers5 and another article published by our group,6 which is more relevant.

Diary of John Page, 1757-1781

Manuscript volume. The first thirty-nine pages include diary entries from Page's years as an undergraduate student at Harvard College. Dated July 1757 through March 1761, entries includes short notes about daily activities. Topics covered include expenses, academics, clothing, and travel to and from Cambridge. Twenty-two pages covering 1764 through 1781 contain brief listings of items, generally foodstuffs, received from male and female Danville parishioners identified by name in Danville. The final twenty-six pages contain notes listing area deaths, as well as his own thoughts on topics such as "of light" and "jealousy." The concluding pages include rules "Concerning Grammar."

A catalogue of books [donated by Jasper Mauduit] in the library of Harvard College [at]: Cambridge in New England, 1765

This leatherbound volume lists books donated to the Harvard College Library by Jasper Mauduit, who served as an agent in London on behalf of the Province of the Massachusetts Bay. Entries are arranged alphabetically and by format; i.e. the first page lists all folios whose author, title, or keyword begin with "A," the next page lists all quartos beginning with "A," and the following page lists all "octavo &ca" volumes beginning with "A." The volume continues in a similar manner for each letter of the alphabet. Following a devastating fire in 1764 which destroyed most of the books in the Harvard College Library, Mauduit donated books, as well as money for the purchase of books, to the College. He also acted as an agent of the Society for Propagating the Gospel in New England and Parts Adjacent, using the £300 they donated for the rebuilding of the College library to select and purchase a large number of books. It is not known if the books listed in this catalog are those donated by Mauduit himself, or if they are the donations he purchased on behalf of the Society. The creator of this volume is unknown; although all entries are made in the same hand, the identity of the writer has not been determined. The label attached to the front cover, which refers to the Lime Street address of Mauduit's business in London, suggests that the list might have been prepared by Mauduit himself.

Diary of Henry Flynt, 1723-1747

This diary, effectively a commonplace book, documents Flynt's daily activities and personal reflections from 1723 to 1747. Many entries concern his dealings with family members, business associates, acquaintances, ministers, and political officials. The diary includes a list of books Flynt loaned to others from 1723 to 1743 and detailed financial entries from 1724 to 1747. These entries provide information about the costs of goods and services, as well as Flynt's consumption habits; they detail where he traveled, what he ate and drank (including, apparently, many pounds of almonds), what he read, and many other aspects of daily life. The diary also contains entries related to Flynt's land holdings and other investments, as well as copies of meeting minutes from several sessions of the Harvard Board of Overseers.

Certification of payment from Oliver Prescott, 1747 September 23

Handwritten certificate of payment for a new red and plaid gown purchased by Harvard sophomore Oliver Prescott in 1747. The certificate is witnessed by upperclassmen Artemas Ward, Jacob Cushing, and Timothy Pond.

Mr. Vaughan's case, March 2, 1724

Opinion (or brief or judgement?) delivered in a case involving a claim by the Colony of New Hampshire to a proprietory right in a ferry running between Portsmouth and Kittery (then in Massachusetts) on the Piscataqua River. The ferry was started in 1684 by John Woodman and conveyed by franchise to Colonel Vaughan by Governor Dudley in 1708. Vaughan died in 1724 and the patent passed to his estate. The town of Portsmouth laid claim to the ferry. Read concluded that this action was not well founded since the ferry is not being operated by possession but by franchise and that, furthermore, New Hampshire does not have complete power over the ferry because Massachusetts has power of franchise on the Kittery end of its route.

Libro quinto de la Arca de este Juzgado de Testamentos de Valladolid ..., 1778-1784

Testamentarias; --Concursos y acreedores; --Capellanias; --Obras pias.

Sermon notes compiled by Warham Williams, 1716-1718

Parchment-bound notebook containing notes kept by Warham Williams on sermons he attended between May 20, 1716 and April 20, 1718, while he was an undergraduate at Harvard College. The notebook includes two chronological tables, at the front and end of the volume, that list the town, lecturer (generally Harvard tutors), biblical text, year, month, day, and part of the day of sermons attended by Williams. The volume contains one-to-two page entries on specific sermons and provides the biblical text and related questions and conclusions. From the front of the volume, the pages contain entries for sermons attended between May 20, 1716 through February 13, 1717. Sermon entries for April 7, 1717 to April 20 1718 are written tête-bêche from the other end of the volume.